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3,200 | Indications for implantable cardioverter defibrillator therapy. | The implantable cardioverter defibrillator (ICD) is now an integral therapy for cardiac patient care. More than 20 years have passed since the first ICD implant. Sudden cardiac death from arrhythmia (ventricular tachycardia and fibrillation) has been significantly decreased because of the use of ICD therapy. Primary treatment trials have shown ICD therapy to be superior to drug therapy. Most of these trials compared ICD therapy with amiodarone or sotalol. Prevention trials have also been completed. Patients with nonsustained ventricular tachycardia, low left ventricular ejection fraction, and coronary artery disease were evaluated with electrophysiology studies. Patients with inducible ventricular arrhythmias were treated with ICD or drug suppression therapy. ICD therapy was superior to drug therapy for prevention of fatal arrhythmias. Ongoing trials include evaluation of ICD therapy for patients with high-risk substrates: congestive heart failure, dilated cardiomyopathy, hypertrophic cardiomyopathy, and repolarization syndromes. Factors such as medication inefficacy/side effects, transvenous ICD implantation and overwhelming mortality benefits have expanded ICD usage beyond the original restrictive guidelines. |
3,201 | Neurological outcome after experimental cardiopulmonary resuscitation: a result of delayed and potentially treatable neuronal injury? | In experimental cardiopulmonary resuscitation (CPR) aortic balloon occlusion, vasopressin, and hypertonic saline dextran administration improve cerebral blood flow. Free radical scavenger alpha-phenyl-N-tert-butyl-nitrone (PBN) and cyclosporine-A (CsA) alleviate neuronal damage after global ischemia. Combining these treatments, we investigated neurological outcome after experimental cardiac arrest.</AbstractText>: Thirty anesthetized piglets, randomly allocated into three groups, were subjected to 8 min of ventricular fibrillation followed by 5 min of closed-chest CPR. The combined treatment (CT) group received all the above-mentioned modalities; group B was treated with balloon occlusion and epinephrine; and group C had sham balloon occlusion with epinephrine. Indicators of oxidative stress (8-iso-PGF(2 alpha)), inflammation (15-keto-dihydro-PGF(2 alpha)), energy crisis (hypoxanthine and xanthine), and anoxia/hypoxia (lactate) were monitored in jugular bulb venous blood. Neurological outcome was evaluated 24 h after CPR.</AbstractText>: Restoration of spontaneous circulation (ROSC) was more rapidly achieved and neurological outcome was significantly better in the CT group, although there was no difference in coronary perfusion pressure between groups. The jugular venous PCO2 and cerebral oxygen extraction ratio were lower in the CT group at 5-15 min after ROSC. Jugular venous 8-iso-PGF(2 alpha) and hypoxanthine after ROSC were correlated to 24 h neurological outcome</AbstractText>: A combination of cerebral blood flow promoting measures and administration of alpha-phenyl-N-tert-butyl-nitrone and cyclosporine-A improved 24 h neurological outcome after 8 min of experimental normothermic cardiac arrest, indicating an ongoing neuronal injury in the reperfusion phase.</AbstractText> |
3,202 | Minimally invasive approach for redo mitral valve surgery: a true benefit for the patient. | Redo mitral valve surgery via sternotomy is associated with a substantial morbidity and mortality. This study evaluated a minimally invasive technique for mitral valve redo procedures.</AbstractText>Out of a series of 394 patients undergoing mitral valve repair or replacement via a right minithoracotomy, 39 patients underwent redo mitral valve surgery (59+/-13 years, 23 female). Previous cardiac surgeries included 17 patients with mitral valve repair, 6 patients with mitral valve replacement, 3 patients with aortic valve replacement, 2 patients with atrial septal defect closure, and 11 patients with coronary artery bypass grafting (CABG). In all cases, femoro-femoral cannulation was performed. The port access technique was applied in patients undergoing redo valve surgery. In patients with prior CABG, the operation was performed using deep hypothermia and ventricular fibrillation.</AbstractText>In all cases, sternotomy was avoided. The mitral valve was replaced in 20 patients and repaired in 19. Time of surgery and cross-clamp time were comparable with the overall series (168+/-73 [redo] vs 168+/-58 min and 52+/-21 [redo] vs 58+/-25 min). Mortality was 5.1%. One patient had transient hemiplegia due to the migration of the endoclamp. All other patients had uneventful outcomes and normal mitral valve function at 3-month's follow-up.</AbstractText>Redo mitral valve surgery can be performed safely using a minimally invasive approach in patients with a previous sternotomy. The right lateral minithoracotomy offers excellent exposure. It minimizes the need for cardiac dissection, and thus, the risk for injury. Avoiding a resternotomy increases patient comfort of redo mitral valve surgery.</AbstractText> |
3,203 | VDD pacing from the middle cardiac vein via a persistent left superior vena cava. | We report a combination of unusual features demonstrating a permanent pacemaker implantation of a single-pass VDD lead by way of an anomalous persistent left superior vena cava in the middle cardiac vein. The ventricular stimulation resembled a right bundle branch block QRS morphology and was successfully synchronized by spontaneous atrial activity. This case illustrates an alternative approach of effective VDD pacing and sensing in patients with such a venous anomaly when other standard implantation sites fail. |
3,204 | Iodine-123-metaiodobenzylguanidine scintigraphy of total cardiac adrenergic denervation in Brugada syndrome. | A 22-year-old Japanese man with Brugada syndrome was resuscitated from cardiopulmonary arrest. In addition to the electrocardiographic evidence of the syndrome and the absence of apparent structural heart disease, no accumulation of iodine-123-metaiodobenzylguanidine (MIBG) was found anywhere throughout the heart. Thallium-201 (Tl) single photon emission computed tomography (SPECT) distribution showed no significant decrease in its uptake. To our knowledge, this is the first report that has demonstrated a homogeneous absence of cardiac accumulation of MIBG in Brugada syndrome. |
3,205 | Silent brain infarction in patients with rheumatic mitral stenosis. | Silent brain infarction (SBI) is defined as asymptomatic infarction areas detected in computerized tomography (CT) scans in patients without a history of stroke. The incidence of SBI is increased in CT or magnetic resonance imaging in patients with carotid stenosis and with atrial fibrillation (AF), but its relation with rheumatic mitral stenosis (MS), another major source of emboli, is uncertain. The aim of this study was to investigate the incidence of SBI in patients with MS. Fifty-three patients with MS (44 females and 9 males; range 25-52 years; mean age 38 +/- 7 years) diagnosed by transthoracic echocardiography (TTE) were enrolled in the study. Mitral valve calcification, left atrium (LA) dimension, and the presence of associating mitral regurgitation on TTE were recorded. Electrocardiographic evaluation was done for rhythm analysis and neurologic examination was performed prior to cerebral CT. Carotid artery Doppler examination was carried out in patients with SBI to exclude carotid artery lesions. Patients with a history of hypertension, diabetes mellitus, anticoagulant drug usage, presence of thrombus in LA, left ventricular segmental or systolic dysfunction, or other valve diseases were excluded from the study. The incidence of SBI was found to be 24.5% in patients with MS (47% cortical, 53% lacunar). SBI was observed to be significantly high in patients with LA dimension > 4 cm or in patients with AF (p < 0.05). The SBI incidence was markedly higher if AF was found with enlarged LA when compared with patients having sinus rhythm and small LA (p < 0.01). When moderate to severe mitral regurgitation was associated with MS, the SBI incidence was found to be lower (p < 0.05). Although SBI was higher in patients with MVA < 1.5 cm2, it was not statistically significant (p > 0.05). No significant correlation was found between calcific and noncalcific valves for SBI (p > 0.05). Our data suggest that SBI may be expected in about 1/4 of patients with MS. The presence of LA enlargement and AF increase the incidence of SBI in patients with MS, whereas the presence of moderate to severe mitral regurgitation decreases the incidence of SBI. |
3,206 | [Stimulation of delta1-opioid receptors increases the ventricular fibrillation threshold in post-infarct cardiosclerosis: the role of K(ATP)-channels]. | Preliminary administration of the delta 1-opioid receptor (delta 1-OR) selective peptide agonist DPDPE (0.1 mg/kg, i.v.) increased the ventricular fibrillation threshold (VFT) in postinfarction cardiosclerosis in rats. Pretreatment with the selective delta 1-OR antagonists ICI 174,864 (not affecting VFT) in a dose of 0.5 mg/kg completely eliminated the DPDPE-induced increase in the VFT. Pretreatment with the KATP channel selective blocker glibenclamide (0.3 mg/kg, i.v.) completely eliminated the delta 1-OR mediated increase in the VFT protective effect of the delta 1-OR stimulation. The intravenous injection of the mitochondrial KATP channel blocker 5-hydroxydecanoate (5 mg/kg) simultaneously with DPDPE not only eliminated the delta 1-OR mediated increase on VFT, but additionally increased the VBFT drop caused by cardiosclerosis. Injected separately, neither glibenclamide nor hydroxydecanoate affected the VFT level. It is concluded that stimulation of the delta 1-OR increases VFT by activating mitochondrial KATP-channels. |
3,207 | [Echocardiography diagnosis of diastolic heart failure]. | Left ventricular diastolic dysfunction can be diagnosed if clinical signs of heart failure and normal ejection fraction are found. Beside clinical signs of heart failure and criteria from catheterization studies like abnormal left ventricular relaxation, filling and/or compliance echocardiography provides valuable parameters for the assessment of diastolic dysfunction.</AbstractText>By the use of various parameters diastolic dysfunction can be differentiated into four degrees of severity, which are of great prognostic importance. If more than one echocardiographic parameter is used, sensitivity for the assessment of diastolic dysfunction becomes nearly 100%. Conventional parameters include isovolumetric relaxation time (IVRT) measured by pulsed Doppler, the ratio of rapid filling and atrial filling velocity (E/A), deceleration time of rapid mitral inflow as well as the ratio of systolic and diastolic pulmonary venous flow velocities. In patients with signs of diastolic heart failure and a normal E/A ratio pulmonary venous flow pattern can help to unmask "pseudonormalization" as the transition from abnormal relaxation to restriction. These parameters, however, are preload-dependent and do not provide intrinsic left ventricular properties. Even in atrial fibrillation, left ventricular filling pressure can be assessed.</AbstractText>Two novel approaches, color Doppler M-mode of left ventricular inflow and tissue Doppler of the mitral annulus, are relatively preload-independent and allow direct estimation of relaxation and filling pressure. By the means of real-time 3-D echocardiography we developed a new method for the non-invasive assessment of rapid filling rate (PFR), thereby completing the echocardiographic approaches to determine diastolic dysfunction.</AbstractText>The broad spectrum of approaches available today makes echocardiography the first choice for the assessment of diastolic dysfunction.</AbstractText> |
3,208 | [Relation between left atrial spontaneous echocontrast and pulmonary venous flow in nonvalvular atrial fibrillation: implications for stratification of thromboembolic risk]. | The links between pulmonary venous flow (PVF) and left atrial stasis have not been adequately defined in nonvalvular atrial fibrillation. In this setting, we aimed to study the relationship between PVF and the occurrence of left atrial spontaneous echocontrast (SEC) in order to evaluate its clinical relevance in the assessment of the cardioembolic risk.</AbstractText>We studied by echocardiography 109 patients with nonvalvular atrial fibrillation (65 males, 44 females, mean age 66 +/- 9 years). The left ventricular end-diastolic and end-systolic diameters, the left ventricular fractional shortening, the left ventricular mass, and the left atrial volume were measured by transthoracic approach. The systolic and diastolic peak velocities of PVF, their ratio (pS/pD) and the velocity-time integrals were assessed by means of transesophageal investigation; furthermore, the presence of left atrial SEC or thrombi was recorded. Among clinical data, thromboembolic events occurring within 15 days before the echocardiographic study, history of hypertension and duration of atrial fibrillation were also collected.</AbstractText>Left atrial SEC showed a significant correlation with left atrial volume (p < 0.001), detection of thrombi (p < 0.001), thromboembolic events (p = 0.002) and pS/pD ratio (p < 0.001). By multivariate analysis, pS/pD ratio was independently correlated with left atrial volume, age and left ventricular fractional shortening (r2 = 0.29, p < 0.001). The sensitivity and specificity of pS/pD ratio to predict the presence of severe SEC was 73.9 and 62.5%, respectively.</AbstractText>In patients with nonvalvular atrial fibrillation, pS/pD ratio is significantly related to the occurrence of left atrial SEC and seems to be a useful parameter concurring to assess left atrial stasis and thromboembolic risk.</AbstractText> |
3,209 | Coronary vasospasm and aborted sudden death treated with an implantable defibrillator and stenting. | In selected patients suffering from variant angina, an implantable cardioverter-defibrillator (ICD) and coronary stenting can be helpful to prevent sudden death and treat coronary artery spasm. We report a case of a 47-year-old woman suffering from variant angina, who experienced an episode of ventricular fibrillation promptly cardioverted. After coronary angiography documentation of a mild atherosclerosis, an ICD was implanted and oral nitrates and calcium antagonists were prescribed. The recurrence of chest pain and palpitations prompted us to perform a second coronary angiography that documented a focal coronary artery spasm successfully treated with stent implantation. No other episodes of angina or ventricular arrhythmia were documented during the following 6 months of follow-up. |
3,210 | Management of the older person with atrial fibrillation. | Atrial fibrillation (AF) is associated with a higher incidence of mortality, stroke, and coronary events than is sinus rhythm. AF with a rapid ventricular rate may cause a tachycardia-related cardiomyopathy. Immediate direct-current (DC) cardioversion should be performed in patients with AF and acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta blockers, verapamil, or diltiazem may be given to slow immediately a very rapid ventricular rate in AF. An oral beta blocker, verapamil, or diltiazem should be used in persons with AF if a fast ventricular rate occurs at rest or during exercise despite digoxin. Amiodarone may be used in selected patients with symptomatic life-threatening AF refractory to other drugs. Nondrug therapies should be performed in patients with symptomatic AF in whom a rapid ventricular rate cannot be slowed by drugs. Paroxysmal AF associated with the tachycardia-bradycardia syndrome should be treated with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in patients with AF and with symptoms such as dizziness or syncope associated with ventricular pauses greater than 3 seconds that are not drug-induced. Elective DC cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than does medical cardioversion in converting AF to sinus rhythm. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective DC or drug cardioversion of AF and should be continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer, especially in older persons, ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiarrhythmic drugs. Digoxin should not be used to treat patients with paroxysmal AF. Patients with chronic or paroxysmal AF at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio of 2.0 to 3.0. Patients with AF at low risk for stroke or with contraindications to warfarin should receive 325 mg of aspirin daily. |
3,211 | Pretreatment with angiotensin-converting enzyme inhibitors attenuates ischemia-reperfusion injury. | The Heart Outcomes Prevention Evaluation (HOPE) trial demonstrated that ischemic events are decreased in patients receiving angiotensin-converting enzyme (ACE) inhibitors. This study sought to determine whether pretreatment with ACE inhibitors would attentuate ischemic injury during surgical revascularization of ischemic myocardium.</AbstractText>In a porcine model, the second and third diagonal vessels were occluded for 90 minutes, followed by 45 minutes of cardioplegic arrest, and 180 minutes of reperfusion. Ten pigs received quinapril (20 mg p.o. q.d.) for 7 days prior to surgery; 10 others received no-ACE inhibitors.</AbstractText>Quinapril-treated animals required less cardioversions for ventricular arrhythmias (1.58 +/- 0.40 vs 2.77 +/- 0.22; p < 0.05), had higher wall motion scores assessed by two-dimensional echocardiography (4 = normal to -1 = dyskinesia; 2.11 +/- 0.10 vs 1.50 +/- 0.07; p < 0.05), more complete coronary artery endothelial relaxation to bradykinin (45% +/- 3% vs 7% +/- 4%; p < 0.005), and lower infarct size (24.0% +/- 3.0% vs 40.0% +/- 1.7%; p < 0.0001).</AbstractText>ACE inhibition prior to coronary revascularization enhances myocardial protection by decreasing ventricular irritability, improving regional wall motion, lowering infarct size, and preserving endothelial function.</AbstractText> |
3,212 | Model of normothermic long-term cardiopulmonary bypass in swine weighing more than eighty kilograms. | Swine models have been used to study cardiovascular disease, cardiac physiology, and transplantation, and have been associated with problems, such as friability of certain organs, anesthesia difficulties, ventricular fibrillation, and edema. We describe a stable model of extended cardiopulmonary bypass (up to 22 h) in swine weighing > 80 kg to be used as a research model.</AbstractText>Swine (n = 5, 88 +/- 6 kg) had both femoral arteries cannulated and after open sternotomy, a two-stage venous catheter was placed in the right atrium/caudal vena cava. The circuit was primed with four parts blood and one part 0.9% NaCl.</AbstractText>Cardiopulmonary bypass was maintained for 10 to 22 h, with the following parameters measured at beginning/middle/end: heart rate, 108 to 134 beats per minute; hematocrit, 30 to 38%; glucose concentration, 4 to 11 mmol/L; lactate concentration 6 to 7 mmol/L; pH 7.4 to 7.5; pCO2, 35 to 38 mmHg; pO2, 197-228 mmHg; HCO3-, 21 to 25 mmol/L; base excess, -3 to +2; and total urine output, 425 to 1,600 ml.</AbstractText>Factors responsible for the success of this model include a higher oxygen concentration on initiation of cardiopulmonary bypass (567 +/- 54 mmHg), maintenance of appropriate hematocrit, and use of non-citrated blood-crystalloid prime. The results indicate a stable model of normothermic long-term cardiopulmonary bypass in swine that allows researchers a longer opportunity for further exploration of relevant research issues.</AbstractText> |
3,213 | Acute pulmonary edema in the emergency department: clinical and echocardiographic survey in an aged population. | This study is aimed at better defining the prevalence of left ventricular dysfunction, atrial fibrillation, and mitral regurgitation in aged patients with cardiogenic acute pulmonary edema.</AbstractText>One hundred and twenty-three consecutive patients with acute pulmonary edema (APE) arriving at the emergency department of a peripheral hospital who underwent Doppler echocardiography within 36 hours of admission were reviewed retrospectively.</AbstractText>Left ventricular ejection fraction (LVEF) was normal or near normal (ie, LVEF > or = 40%) in 41.4% (n = 51 patients), and depressed in 58.5% (n = 72). Significant valvular dysfunction was present in 37.4%; mitral regurgitation was the most frequent (22.8%; n = 28). We found a significant positive correlation between systolic blood pressure (SBP) and LVEF (P = 0.003). Within the group of patients presenting with lower SBP (< or = 140 mm Hg), as blood pressure diminished, LVEF also diminished significantly (P = 0.008). In a logistic regression analysis, male sex and SBP of less than 120 mm Hg were found to be the strongest predictors for LVEF < or = 40%, conferring a 2.68- and 2.73-fold risk, respectively (95%CI, 1.19 to -6.00; P = 0.016 and 95%CI, 0.956-7.80; P = 0.061, respectively) compared with female sex and higher SBP groups.</AbstractText>This study emphasizes that emergency departments should have clear-cut policies for diagnosing and treating acute coronary syndromes and tachyarrhythmias, as being potential treatable causes of APE. Once stabilized, patients should be examined for treatable valvular causes. A further study, of acute echocardiography done upon arrival to the emergency department in patients with APE is warranted.</AbstractText> |
3,214 | Acute myocardial infarction with patent coronary artery after a long-distance flight--a case report. | Acute myocardial infarction is unusual in a young woman, especially with normal coronary arteriography. There are several mechanisms hypothesized, including coronary artery embolism, coronary spasm, illegal drug abuse and toxic condition. However, the etiology could be detected in only one third of these patients. Although air travel is known to precipitate deep vein thrombosis and pulmonary embolism, it is unclear whether it also causes myocardial infarction. We report a 37 year-old woman who had no risk factor for coronary artery disease, who suffered from acute myocardial infarction complicated with ventricular fibrillation after a long-distance flight across the Pacific Ocean from the United States to Taiwan. The coronary arteriogram disclosed patent coronary artery with slight intraluminal haziness in the proximal left anterior descending artery. The left ventriculogram demonstrated akinesia of anterolateral and apical segments with apical thrombus formation. We reviewed the related literature and considered the myocardial infarction in this patient was related to coronary thrombus formation after long-distance air travel. |
3,215 | Protected carotid stenting: safety and efficacy of the MedNova NeuroShield filter. | Neuroprotection during carotid stenting has the potential to reduce procedural atheroembolic sequelae. We report the United Kingdom experience of NeuroShield (MedNova Ltd, Horsham, West Sussex, United Kingdom).</AbstractText>We performed a prospective cohort analysis of 50 consecutive patients (50 lesions) in a regional vascular tertiary referral center (catchment area one million) that provides an institutional service for the short term. The subjects were all the patients referred for carotid stenting after preassessment by a multidisciplinary team. All the patients underwent pretreatment with antiplatelet agents. Forty-two patients had atherosclerotic stenosis of the carotid bifurcation between 70% and 95% (with North American Symptomatic Carotid Endarterectomy Trial criteria). Six patients had restenosis after endarterectomy. Two had previous local radiotherapy. Forty-two patients were symptomatic (amaurosis fugax/central retinal artery occlusion in 11 cases, and hemispheric transient ischemic attack/cerebrovascular accident in 31 cases). Eight patients were asymptomatic with bilateral high-grade stenoses, with six cases before coronary artery bypass grafting. The intervention performed was protected primary carotid stenting. Outcome measures were procedural atheroembolic events, including all-stroke and death rates up to 30 days, and analysis of retrieved debris in a subset of 11 cases.</AbstractText>The technical success rate was 50/50 (100%) for stenting and 49/50 (98%) for filter placement/retrieval. Technical complications comprised nonsymptomatic spasm at the filter site (flow limiting in two cases and non-flow limiting in five cases). Procedural events were one minor stroke (patient fully recovered within 48 hours) in a complex clinical setting and one ventricular fibrillation arrest in a patient before coronary artery bypass grafting who was resuscitated without neurologic event. At 30 days, the death or major disability from stroke rate was 2/50 (4%). No cases were atheroembolic. The all-stroke/death rate was 3/50 (6%). The two deaths were the result of a fatal hemorrhagic stroke that occurred at 4 days and was thought to be caused by reperfusion and a perforated ventricle caused by a temporary pacing wire. One femoral pseudoaneurysm followed failed closure device deployment and required percutaneous thrombin injection. The mean particle number per patient was 12 (range, 0 to 41). The mean particle diameter was 284.9 microm(range, 31 to 1430 microm). The mean ellipsoid volume load was 0.1602 mm(3) (range, 0.0005 to 0.1968 mm(3)).</AbstractText>Carotid stenting protected with NeuroShield is safe. The filter traps embolic debris liberated during the procedure.</AbstractText> |
3,216 | Isolated annular dilation does not usually cause important functional mitral regurgitation: comparison between patients with lone atrial fibrillation and those with idiopathic or ischemic cardiomyopathy. | We sought to test whether isolated mitral annular (MA) dilation can cause important functional mitral regurgitation (MR).</AbstractText>Mitral annular dilation has been considered a primary cause of functional MR. Patients with functional MR, however, usually have both MA dilation and left ventricular (LV) dilation and dysfunction. Lone atrial fibrillation (AF) can potentially cause isolated MA dilation, offering a unique opportunity to relate MA dilation to leaflet function.</AbstractText>Mid-systolic MA area, MR fraction, LV volumes and papillary muscle (PM) leaflet tethering length were compared by echocardiography among 18 control subjects, 25 patients with lone AF and 24 patients with idiopathic or ischemic cardiomyopathy (ICM).</AbstractText>Patients with lone AF had a normal LV size and function but MA dilation (isolated MA dialtion) significant and comparable to that of patients with ICM (MA AREA: 8.0 +/- 1.2 vs. 11.6 +/- 2.3 vs. 12.5 +/- 2.9 cm(2) [control vs. lone AF vs. ICM]; p < 0.001 for both lone AF and ICM). However, patients with lone AF had only modest MR, compared with that of patients with ICM (MR fraction: -3 +/- 8% vs. 3 +/- 9% vs. 36 +/- 25%; p < 0.001 for patients with ICM). Multivariate analysis identified PM tethering length, not MA dilation, as an independent primary contributor to MR.</AbstractText>Isolated annular dilation does not usually cause moderate or severe MR. Important functional MR also depends on LV dilation and dysfunction, leading to an altered force balance on the leaflets, which impairs coaptation.</AbstractText> |
3,217 | Multisystem dystrophy syndrome due to novel missense mutations in the amino-terminal head and alpha-helical rod domains of the lamin A/C gene. | Mutations in different domains of the LMNA (lamin A/C) gene encoding nuclear envelope proteins lamin A and lamin C cause familial partial lipodystrophy (Dunnigan variety), dilated cardiomyopathy, and autosomal dominant forms of Emery-Dreifuss and limb-girdle muscular dystrophies. The objective of this study was to evaluate LMNA variants in two families with familial partial lipodystrophy (Dunnigan variety) who also had cardiac conduction system defects and other manifestations related to cardiomyopathy. We performed mutational analysis of the lamin A/C gene in affected and unaffected subjects by deoxyribonucleic acid sequencing of the exons. Two novel missense mutations were identified in exon 1 of the lamin A/C gene. One mutation, R28W (CGG-->TGG), affected the amino-terminal head domain, and the other, R62G (CGC-->GGC), affected the alpha-helical rod domain. Affected subjects from both families had an increased prevalence of cardiac manifestations, such as atrioventricular conduction defects, atrial fibrillation, and heart failure due to ventricular dilatation, as well as pacemaker implantation. The proband from one of the families also had proximal muscle weakness. Novel genetic defects in the LMNA gene in two families with the Dunnigan variety of familial partial lipodystrophy, cardiac conduction system defects, and other manifestations related to cardiomyopathy suggest the occurrence of a multisystem dystrophy syndrome due to LMNA mutations. |
3,218 | Effectiveness and cost-effectiveness of implantable cardioverter defibrillators in the treatment of ventricular arrhythmias among medicare beneficiaries. | The implantable cardioverter defibrillator has been assessed in randomized trials, but the generalizability of trial results to broader clinical settings is unclear. Our purpose was to evaluate the outcomes and costs of defibrillator use in an unselected population.</AbstractText>We identified 125,892 Medicare patients who were discharged between 1987 and 1995 after hospitalization with a primary diagnosis of ventricular tachycardia or ventricular fibrillation, 7789 of whom (6.2%) received a defibrillator. We used a multivariable propensity score that included patient and hospital characteristics to match pairs of patients, in which one patient received a defibrillator and the other did not. We compared mortality and costs in these 7612 matched pairs during 8 years of follow-up.</AbstractText>Patients who received a defibrillator were more likely to be younger, white, male, and urban dwelling, and to have ischemic heart disease, heart failure, or a history of ventricular fibrillation. In the matched-pairs analysis, those who received a defibrillator had significantly lower mortality: 11% versus 19% at 1 year (odds ratio [OR] = 0.57; 95% confidence interval [CI]: 0.51 to 0.63), 20% versus 30% at 2 years (OR = 0.66; 95% CI: 0.60 to 0.72), and 28% versus 39% at 3 years (OR = 0.70; 95% CI: 0.63 to 0.77). These patients also had lower mortality at 8 years (P = 0.0001), although this advantage over patients who received medical treatment only decreased over time. Expenditures among defibrillator recipients were consistently higher, with a cost-effectiveness ratio of $78,400 per life-year gained.</AbstractText>The use of implantable defibrillators was associated with significantly lower mortality and higher costs, whereas the cost-effectiveness was higher than many, but not all, generally accepted therapies.</AbstractText> |
3,219 | Comparison of permanent left ventricular and biventricular pacing in patients with heart failure and chronic atrial fibrillation: prospective haemodynamic study. | To compare clinical and haemodynamic variables between left ventricular and biventricular pacing in patients with severe heart failure; and to analyse haemodynamic changes during daily life and maximum exercise during chronic left ventricular and biventricular pacing.</AbstractText>Prospective single blinded randomised study with crossover.</AbstractText>University hospital (tertiary referral centre).</AbstractText>13 patients (mean (SD) age, 62 (6) years) with chronic atrial fibrillation, severe heart failure (mean ejection fraction 24 (8)%), and QRS prolongation of > or = 140 ms had His bundle ablation and installation of a pacemaker providing left ventricular and biventricular pacing. The pacemaker was equipped with a peak endocardial acceleration (PEA) sensor. The PEA pattern was used as a haemodynamic marker during exercise as it is highly correlated with left ventricular dP/dt. After a baseline period of right ventricular pacing, all patients had two months of left ventricular pacing and two months of biventricular pacing in random order. At the end of each phase, an echocardiogram, a haemodynamic analysis at rest and on exercise during a six minute walk test, and a cardiopulmonary exercise test were performed.</AbstractText>PEA values were higher with left ventricular pacing (0.58 (0.38) m/s) and biventricular pacing (0.62 (0.24) m/s) than at baseline (0.49 (0.18) m/s) (p < 0.05). The six minute walk test showed similar performance in both pacing modes, but patients had more symptoms with left ventricular pacing at the end of the test (p = 0.035). On cardiopulmonary exercise testing, there was a greater increase in mean percentage variation of PEA with biventricular pacing than with left ventricular pacing (125 (18)% v 97 (36)%, respectively; p = 0.048) and better performance figures (92 (34) W v 77 (23) W; p = 0.03).</AbstractText>During symptom limited and daily life exercise tests, chronic biventricular pacing provides better haemodynamic performance than left ventricular pacing. In heart failure patients with wide QRS complexes, the interventricular dyssynchronisation induced by left ventricular pacing may impair myocardial function during exercise.</AbstractText> |
3,220 | Cardiac membrane fatty acid composition modulates myocardial oxygen consumption and postischemic recovery of contractile function. | Regular fish consumption is associated with low cardiovascular disease morbidity and mortality. Fish oils modify cardiac membrane phospholipid fatty acid composition with potent antiarrhythmic effects. We tested the effects of dietary fish oil on ventricular hemodynamics and myocardial oxygen consumption (MVO2).</AbstractText>Male Wistar rats were fed for 16 weeks on a reference diet rich in n-6 polyunsaturated fatty acids (PUFA), a diet rich in saturated animal fat (SAT), or a diet rich in n-3 PUFA from fish oil. Isolated working hearts were perfused with porcine erythrocytes (40% hematocrit) at 75 mm Hg afterload with variable preload (5 to 20 mm Hg) or with low coronary flow ischemia with maintained afterload, preload, and heart rate, then reperfused. MVO2 was low and coronary perfusion reserve high in n-3 PUFA hearts, and cardiac output increased with workload. The n-3 PUFA reduced ischemic markers-acidosis, K+, lactate, and creatine kinase-and increased contractile recovery during reperfusion. SAT hearts had high MVO2, low coronary perfusion reserve, and poor contractile function and recovery. Dietary differences in MVO2 were abolished by KCl arrest (basal metabolism) or ruthenium red (3.4 micromol/L) but not by ryanodine (1 nmol/L). Fish oil or ryanodine, but not ruthenium red, prevented ventricular fibrillation in reperfusion.</AbstractText>Dietary fish oil directly influenced heart function and improved cardiac responses to ischemia and reperfusion. The n-3 PUFA reduced oxygen consumption at any given work output and increased postischemic recovery. Thus, direct effects on myocardial function may contribute to the altered cardiovascular disease profile associated with fish consumption.</AbstractText> |
3,221 | Effects of interrupting precordial compressions on the calculated probability of defibrillation success during out-of-hospital cardiac arrest. | Cardiopulmonary resuscitation (CPR) creates artifacts on the ECG and, with automated defibrillators, a pause in CPR is mandatory during rhythm analysis. The rate of return of spontaneous circulation (ROSC) is reduced with increased duration of this hands-off interval in rats. We analyzed whether similar hands-off intervals in humans with ventricular fibrillation causes changes in the ECG predicting a lower probability of ROSC.</AbstractText>The probability of ROSC after a shock was continually determined from ECG signal characteristics for up to 20 seconds of 634 such hands-off intervals in patients with ventricular fibrillation. In hands-off intervals with an initially high (40% to 100%) or median (25% to 40%) probability for ROSC, the probability was gradually reduced with time to a median of 8% to 11% after 20 seconds (P<0.001). In episodes with a low initial probability (0% to 25%; median, 5%), there was no further reduction with time.</AbstractText>The interval between discontinuation of chest compressions and delivery of a shock should be kept as short as possible.</AbstractText> |
3,222 | Simultaneous sterno-thoracic cardiopulmonary resuscitation improves short-term survival rate in canine cardiac arrests. | We have reported previously that simultaneous sterno-thoracic cardiopulmonary resuscitation (SST-CPR) using a device that compresses the sternum and constricts the thorax circumferentially during a compression systole that can be achieved using standard cardiopulmonary resuscitation (STD-CPR). This study was designed to assess whether SST-CPR improves the survival rate of dogs with cardiac arrest compared with STD-CPR. Twenty-nine mongrel dogs (19-31 kg) were enrolled in this study. After 4 min of ventricular fibrillation induced by an AC current, animals were randomized to be resuscitated by either STD-CPR (n=15) or SST-CPR (n=14). Defibrillation was attempted 10 min after the induction of cardiac arrest. Standard advanced cardiac life support was started if defibrillation was unsuccessful. Aortic blood pressure, coronary perfusion pressure, and end tidal CO(2) tension were measured during CPR and the post-resuscitation period. Survival was determined 12 h after the induction of cardiac arrest. SST-CPR resulted in a significantly (P<0.001) higher systolic arterial pressure (91+/-47 vs 47+/-24 mmHg), diastolic pressure (43+/-24 vs 17+/-10 mmHg), coronary perfusion pressure (35+/-25 vs 13+/-9 mmHg), and end tidal CO(2) tension (9+/-4 vs 3+/-2 mmHg). Two of 15 animals (13%) resuscitated by STD-CPR and seven of 14 animals (50%) resuscitated by SST-CPR survived for 12 h after cardiac arrest (P<0.05). In conclusion, SST-CPR improves the short-term survival rate in canine cardiac arrest compared with STD-CPR. |
3,223 | Resuscitation from cardiac arrest with adrenaline/epinephrine or vasopressin: effects on intestinal mucosal tonometer pCO(2) during the postresuscitation period in rats. | The use of vasopressin instead of adrenaline/epinephrine during resuscitation improves vital organ perfusion, but the effects on mesenteric perfusion following successful resuscitation are not fully evaluated. The present study was designed to compare the effects of vasopressin and adrenaline/epinephrine, given to rats during resuscitation from ventricular fibrillation, on to mesenteric ischaemia, as determined by intestinal mucosal tonometer pCO(2) during the postresuscitation period.</AbstractText>Male Sprague-Dawley rats (n=28) were allocated randomly to receive vasopressin (0.8 U/kg) or adrenaline/epinephrine (90 microg/kg) after 5 min of ventricular fibrillation. Precordial chest compression was initiated 4 min after the start of ventricular fibrillation, continued for 4 min, and followed by defibrillation. Seven of 14 (vasopressin) and 12 of 14 (adrenaline/epinephrine) rats were successfully defibrillated (P=0.10, Fisher's exact test) and observed for 60 min. Intestinal mucosal tonometer pCO(2) measurements before cardiac arrest and 15, 30, and 60 min following return of spontaneous circulation were 47+/-3, 73+/-8, 63+/-7, and 56+/-6 mmHg in the vasopressin group and 48+/-5, 78+/-7, 67+/-6, and 62+/-6 mmHg in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine). Right atrial hemoglobin oxygen saturations at these time points were 73+/-5, 51+/-12, 58+/-11, and 63+/-5% in the vasopressin group and 76+/-7, 44+/-10, 52+/-10 and 54+/-8% in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine).</AbstractText>We conclude that in this rat model the administration of vasopressin instead of adrenaline/epinephrine for CPR tends to be associated with lower resuscitation success, but less mesenteric ischaemia during the postresuscitation period in successfully resuscitated rats.</AbstractText> |
3,224 | Characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to whether the arrest took place during office hours. | To describe the characteristics and outcome among patients suffering from in hospital cardiac arrest in relation to whether the arrest took place during office hours.</AbstractText>All patients suffering in hospital cardiac arrest in Sahlgrenska University hospital in Göteborg, Sweden between 1994 and 1999 in whom resuscitative efforts were attempted and for whom the time when the cardiopulmonary resuscitation (CPR) team was alerted.</AbstractText>Prospective recording of various factors at resuscitation including the time when the CPR team was alerted. Retrospective evaluation via medical records of patients previous history and final outcome.</AbstractText>Among patients in whom the arrest took place during office hours (08:00-16:30 h) the overall survival rate was 49% as compared with 26% among the remaining patients (P<0.0001). The corresponding figures for patients found in ventricular fibrillation were 66 and 44% (P=0.0001), for patients found in asystole 33 and 22% (NS) and for patients found in pulseless electrical activity 14 and 3% (NS). When correcting for dissimilarities in previous history and factors at resuscitation the adjusted odds ratio for patients to be discharged alive who had the arrest during office hours was 2.07 (1.40-3.06) as compared with patients who had an arrest outside office hours.</AbstractText>Among patients suffering from in hospital cardiac arrest and in whom CPR was attempted those who had the arrest during office hours had a survival rate being more than twice that of patients who had the arrest during other times of the day and night. These results indicate that the preparedness for optimal treatment of in hospital cardiac arrest is of ultimate importance for the final outcome and that an increased preparedness during evenings and nights might increase survival among patients suffering from in hospital cardiac arrest.</AbstractText> |
3,225 | Atrial natriuretic peptide level after cardioversion of chronic atrial fibrillation. | Heart endocrine studies concerning patients with chronic atrial fibrillation (AF) have become increasingly important. Atrial natriuretic peptide (ANP) is released from atrial myocytes. The increased level of ANP in patients with AF is probably caused by the hemodynamic effect of the arrhythmia. The aim of this study was to explore plasma ANP levels in patients with chronic AF and to describe plasma ANP concentration changes following sinus rhythm (SR) restoration. The study group was comprised of 42 patients, aged between 43 and 76 years with chronic AF (more than 1 month) and a relatively controlled ventricular response (85.8+/-11.3 beats/min). Plasma ANP levels were measured before and 24 h after AF cardioversion. The control group comprised of 11 subjects. All had normal SR without history of AF and were compatible in age, sex and concomitant diseases with the examined group. ANP level values were expressed as mean+/-standard deviation. The mean plasma ANP level in the AF group was significantly higher than in the control group (59.5+/-15.6 vs. 34.3+/-10.2 pg/ml, P<0,001). Electrical or pharmacological cardioversion was performed in 42 patients. SR was successfully restored in 35 patients. Plasma ANP concentrations decreased significantly from baseline values (from 59.4+/-16.6 to 31.4+/-15.0 pg/ml, P<0.001) 24 h after cardioversion in the successful group, while they remained unchanged (60.2+/-10.7 to 59.4+/-10.4 pg/ml, NS) in patients with an unsuccessful cardioversion.</AbstractText>The mean concentration of ANP in patients with chronic AF was nearly two-times higher than in the control group with sinus rhythm. Conversion to SR was associated with a significant decrease and normalization in plasma ANP concentrations.</AbstractText> |
3,226 | Implantable cardioverter defibrillator implantation rates in the Olmsted County, Minnesota, population: 1989-1999. | Although the efficacy of implantable cardioverter defibrillators (ICDs) has been demonstrated in randomized clinical trials, implantation and survival rates have not been reported for a defined population. We performed a retrospective cohort analysis of Olmsted County, Minnesota residents (n = 70) who received their first ICD between 1 January 1989 and 31 December 1999. The ICD implantation rate increased from approximately 2.5/100,000 (95% confidence interval [CI], 0.9-4.1) in the first 4 years to 11.5/100,000 (95% CI, 6.7-16.2) in the last 2 years. Twenty-three patients (33%) received an appropriate ICD shock during the observation period. Based on these data, ICDs are estimated to reduce total mortality rates in this population by 0.3%. We conclude that, in patients drawn from a community setting with AHA/ACC class I indications for ICD implantation, implantation of ICDs appears to be highly efficacious in aborting potentially fatal events. |
3,227 | Effects of epinephrine and vasopressin in a piglet model of prolonged ventricular fibrillation and cardiopulmonary resuscitation. | We recently demonstrated that vasopressin alone resulted in a poorer outcome in a pediatric porcine model of asphyxial cardiac arrest when compared with epinephrine alone or with epinephrine plus vasopressin in combination. Accordingly, this study was designed to differentiate whether the inferior effects of vasopressin in pediatrics were caused by the type of cardiac arrest.</AbstractText>Prospective, randomized laboratory investigation that used an established porcine model for measurement of hemodynamic variables and organ blood flow.</AbstractText>University hospital laboratory.</AbstractText>Eighteen piglets weighing 8-11 kg.</AbstractText>After 8 mins of ventricular fibrillation and 8 mins of cardiopulmonary resuscitation, either 0.4 units/kg vasopressin (n = 6), 45 microg/kg epinephrine (n = 6), or a combination of 45 microg/kg epinephrine with 0.8 units/kg vasopressin (n = 6) was administered. Six minutes after drug administration, a second respective bolus dose of 0.8 units/kg vasopressin, 200 microg/kg epinephrine, or a combination of 200 microg/kg epinephrine with 0.8 units/kg vasopressin was given. Defibrillation was attempted 20 mins after initiating cardiopulmonary resuscitation.</AbstractText>Mean +/- sem left ventricular myocardial blood flow 2 mins after each respective drug administration was 65 +/- 4 and 70 +/- 13 mL x min(-1) x 100 g(-1) in the vasopressin group; 83 +/- 42 and 85 +/- 41 mL x min(-1) x 100 g(-1) in the epinephrine group; and 176 +/- 32 and 187 +/- 29 mL x min(-1) x 100 g(-1) in the epinephrine-vasopressin group (p <.006 after both doses of epinephrine-vasopressin vs. vasopressin and after the first dose of epinephrine-vasopressin vs. epinephrine, respectively). At the same times, mean +/- sem total cerebral blood flow was 73 +/- 3 and 47 +/- 5 mL x min(-1) x 100 g(-1) after vasopressin; 18 +/- 2 and 12 +/- 2 mL x min(-1) x 100 g(-1) after epinephrine; and 79 +/- 21 and 41 +/- 8 mL x min(-1) x 100 g(-1) after epinephrine-vasopressin (p <.025 after both doses of vasopressin and epinephrine-vasopressin vs. epinephrine). Five of six vasopressin-treated, two of six epinephrine-treated, and six of six epinephrine-vasopressin treated animals had return of spontaneous circulation (nonsignificant).</AbstractText>In this pediatric porcine model of ventricular fibrillation, the combination of epinephrine with vasopressin during cardiopulmonary resuscitation resulted in significantly higher levels of left ventricular myocardial blood flow than either vasopressin alone or epinephrine alone. Both vasopressin alone and the combination of epinephrine with vasopressin, but not epinephrine alone, improved total cerebral blood flow during cardiopulmonary resuscitation. In stark contrast to asphyxial cardiac arrest, vasopressin alone or in combination with epinephrine appears to be of benefit after ventricular fibrillation in the pediatric porcine model.</AbstractText> |
3,228 | Relationship between late potentials and myocardial viability assessed by dobutamine echocardiography in the early postinfarction period. | In the postmyocardial infarction period, late potentials (LPs) are a sensitive marker for the occurrence of sustained ventricular tachycardia and ventricular fibrillation. The relationship between positive signal-averaged electrocardiogram (SAECG) and myocardial viability remains controversial. The aim of the present study was to assess prospectively the possible relationship between LPs and myocardial viability detected by dobutamine stress echocardiography (DSE) in the early period after myocardial infarction (AMI), before hospital discharge.</AbstractText>Ninety-nine patients with AMI were included prospectively in the study. The mean age was 58 +/- 11 years, 17 were women and 82 were men. All patients had SAEG and DSE, and 94 had coronary angiography before hospital discharge.</AbstractText>In the overall population, presence of viability was demonstrated in fewer patients with LPs [37 of 70 (52%)] than absence of viability [18 of 29 (62%)] but the difference did not reach statistical significance. In the subgroup of patients with left ventricular ejection fraction (LVEF) lower than 40%, at higher risk of arrhythmias, the presence of viability was associated with the absence of LPs: 80% of the patients without LPs had viability by DSE (P < 0.01) and only 35% of patients with LPs had viability by DSE (not significant).</AbstractText>In patients with an acute myocardial infarction and with low ejection fraction (<40%), the absence of LPs is related to the presence of viable myocardium as assessed by DSE early after the acute event. These data also suggest that myocardial viability is not the substrate for LPs in this population.</AbstractText> |
3,229 | Cardioprotective effect of ischemic preconditioning is preserved in food-restricted senescent rats. | Ischemic preconditioning (PC) has been proposed as an endogenous form of protection against-ischemia reperfusion injury. We have shown that PC does not prevent postischemic dysfunction in the aging heart. This phenomenon could be due to the reduction of cardiac norepinephrine release, and it has also been previously demonstrated that age-related decrease of norepinephrine release from cardiac adrenergic nerves may be restored by caloric restriction. We investigated the effects on mechanical parameters of PC against 20 min of global ischemia followed by 40 min of reperfusion in isolated hearts from adult (6 mo) and "ad libitum"-fed and food-restricted senescent (24 mo) rats. Norepinephrine release in coronary effluent was determined by high-performance liquid chromatography. Final recovery of percent developed pressure was significantly improved after PC in adult hearts versus unconditioned controls (85.2 +/- 19% vs. 51.5 +/- 10%, P < 0.01). The effect of PC on developed pressure recovery was absent in ad libitum-fed rats, but it was restored in food-restricted senescent hearts (66.6 +/- 13% vs. 38.3 +/- 11%, P < 0.05). Accordingly, norepinephrine release significantly increased after PC in both adult and in food-restricted senescent hearts, and depletion of myocardial norepinephrine stores by reserpine abolished the PC effect in both adult and in food-restricted senescent hearts. We conclude that PC reduces postischemic dysfunction in the hearts from adult and food-restricted but not in ad libitum-fed senescent rats. Despite the possibility of multiple age-related mechanisms, the protection afforded by PC was correlated with increased norepinephrine release, and it was blocked by reserpine in both adult and food-restricted senescent hearts. Thus caloric restriction may restore PC in the aging heart probably via increased norepinephrine release. |
3,230 | Effects of left ventricular systolic dysfunction on left atrial appendage and left atrial functions in patients with chronic nonvalvular atrial fibrillation. | It has been claimed that left ventricular (LV) systolic dysfunction impairs left atrial (LA) and left atrial appendage (LAA) functions. In this study, we compared the LA and LAA function parameters in patients with chronic nonvalvular atrial fibrillation (AF) with and without LV systolic dysfunction.</AbstractText>The study population consisted of 28 patients with chronic nonvalvularAF. Group I consisted of 12 patients with LV systolic dysfunction (mean age: 61 +/- 14 years; LV ejection fraction: 44 +/- 6%), group II of 16 patients with normal LV systolic function (mean age: 52 +/- 15 years; LV ejection fraction: 65 +/- 3%). LV ejection fraction (EF) was measured by echocardiography utilizing bi-plane area length method. The following LA and LAA transoesophageal echocardiography parameters were obtained: I) LA diameter, 2) LAA ejection velocity, 3) LAA filling velocity, 4) LAA ejection fraction, 5) pulmonary venous (PV) systolic velocity, 6) PV diastolic velocity, 7) PV systolic velocity/diastolic velocity ratio. The left atrium diameter was significantly larger in group I than in group 11 (4.7 +/- 0.7 cm vs. 3.8 +/- 0.6 cm, p < 0.05). The LAA ejection velocity and LAA ejection fraction were significantly lower in group I than in group 11 (22.6 +/- 15.5 cm/s vs 37.5 +/- 11.3 cm/s and 26.9 +/- 20.8% vs. 41.3 +/- 10.9%, p < 0.05 for both comparisons). The PV systolic velocity and PV systolic velocity/diastolic velocity ratio were significantly smaller in group I than in group II (26.2 +/- 14.8 cm/s vs. 51.5 +/- 22 cm/s and 0.7 +/- 0.6 vs. 1.2 +/- 0.5, p < 0.05 for both comparisons). Although decreased LAA filling and PV diastolic velocities were determined in group I, no significant difference existed between groups I and II. Thrombus and/or spontaneous echo contrast (SEC) in the LA and/or LAA were more frequent in group I (75% vs. 18%, p < 0.05).</AbstractText>These results indicate that LV systolic dysfunction impairs various LA and LA function parameters and is associated with an increased frequency of SEC and/or LA thrombus in patients with chronic nonvalvularAF.</AbstractText> |
3,231 | Cardioprotective effects of chronic hypoxia and ischaemic preconditioning are not additive. | The objective of the work was to examine whether adaptation to intermittent high altitude hypoxia and ischaemic preconditioning provide additive protection of the heart against subsequent acute ischaemic injury. Adult male rats were exposed to hypoxia (7000 m, 8 h/day, 24-30 exposures) in a hypobaric chamber. Susceptibility of their hearts to ischaemia-induced ventricular arrhythmias and infarction was evaluated in open-chest animals subjected to 30-min coronary artery occlusion and 4-h reperfusion. Preconditioning was induced by either two (PC1) or five (PC2) occlusions of the same artery for 5 min, each followed by 5-min reperfusion. Adaptation to hypoxia decreased the arrhythmia score from 2.75 +/- 0.13 in normoxic controls to 2.17 +/- 0.18. Both PC1 and PC2 reduced the arrhythmia score in the controls (0.15 +/- 0.10 and 0.71 +/- 0.24, respectively), as well as in the hypoxic groups (0.40 +/- 0.15 and 0.27 +/- 0.15, respectively). The infarct size was reduced from 66.6 +/- 2.3% of the area at risk in the controls to 50.2 +/- 1.9% in the adapted rats. PC1 conferred further protection in adapted animals (38.4 +/- 2.8%) but this combined effect was of the same magnitude as that of preconditioning in the controls (37.5 +/- 1.6%). Similar results were obtained using PC2. It is concluded that adaptation to hypoxia decreases the efficiency of ischaemic preconditioning; cardioprotective effects of these two phenomena are not additive. The results are consistent with the view that the mechanisms of protection conferred by chronic hypoxia and preconditioning may share the same signalling pathway. |
3,232 | In-vivo measurement of swine myocardial resistivity. | We used a four-terminal plunge probe to measure myocardial resistivity in two directions at three sites from the epicardial surface of eight open-chest pigs in-vivo at eight frequencies ranging from 1 Hz to 1 MHz. We calibrated the plunge probe to minimize the error due to stray capacitance between the measured subject and ground. We calibrated the probe in saline solutions contained in a metal cup situated near the heart that had an electrical connection to the pig's heart. The mean of the measured myocardial resistivity was 319 ohm x cm at 1 Hz down to 166 ohm x cm at 1 MHz. Statistical analysis showed the measured myocardial resistivity of two out of eight pigs was significantly different from that of other pigs. The myocardial resistivity measured with the resistivity probe oriented along and across the epicardial fiber direction was significantly different at only one out of the eight frequencies. There was no significant difference in the myocardial resistivity measured at different sites. |
3,233 | [Sudden death. Role of the electrophysiologic study]. | At present, sudden death is considered a major health problem, DeBoer in 1935, recognized the clinical importance of ventricular fibrillation as the cause of sudden cardiac death. Sudden death due to cardiovascular problems has been established as one of the main causes of death in the developed countries and in developing countries as ours, where the deaths caused by cardiovascular diseases represent 15% of the total, exceeding other causes of death. The frequency of sudden death in our country is unknown, but more frequently we hear about cases of patients that have been reanimated for cardiac arrest; in the United States of America the frequency has been estimated between 400,000 at 500,000 per year although, recently, 250,000 at 300,000 events are being mentioned. It is convenient to comment that the causal arrhythmias are diverse and may vary depending on the underlying disease, although, generally, it can be pointed out that 80% of them are due to tachyarrhythmias. It's important to point out that there is a strong relationship between left ventricular dysfunction, the frequency of ventricular arrhythmias, and fatal cardiac events due to cardiac rhythm disturbances. The recommendations for electrophysiological studies are: 1) patients surviving cardiac arrest, occurring without evidence of an acute Q-wave myocardial infarction and 2) patients surviving cardiac arrest occurring more than 48 hours after the acute phase of myocardial infarction in the absence of a recurrent ischemic event. |
3,234 | The role of approximate entropy in predicting ventricular defibrillation threshold. | The role of myocardial tissue mass on ventricular defibrillation threshold (DFT) is unclear. We hypothesized that changes in tissue mass modulate DFT by changing ventricular fibrillation (VF) wavefront regularity (entropy).</AbstractText>The right ventricles (RV) of seven farm pigs were isolated, superfused and perfused through the right coronary artery with oxygenated Tyrode's solution at 37 degrees C. The epicardial surface was stained with the voltage sensitive dye, di-4-ANEPPS, and activation wavefront numbers (AWN) during VF were determined from the optical maps using a CCD camera (96 x 96 pixels over a 3.5 x 3.5 cm area). The RV mass was progressively reduced by sequential cutting of 1 to 2 g of tissue (approximately 12 cuts in total) distal to the perfusion site. After each cut, VF was reinduced, optical maps obtained, and the 50% probability of successful DFT(50) determined using an up-down algorithm. After each cut, the approximate entropy (ApEn) was also computed using 5 seconds of VF data obtained with a bipolar electrode and a pseudo-electrocardiogram. Tissue mass reduction of up to one third of the RV mass (ie, from 48.4 +/- 4.25 g to 34 +/- 4.7 g) caused little or no change in the DFT, ApEn or AWN. However, further progressive reduction of the RV mass near the critical mass of VF resulted in a significant (P < 0.05) progressive decrease in all three measured parameters. DFT energy was reduced by 27% (1.47 +/- 0.34 J vs. 1.02 +/- 0.14 J). There was a significant (P < 0.01) correlation between the DFT and ApEn, which significantly further increased (P < 0.001) near the critical mass. In a separate series of 6 isolated RVs, the ApEn correlated well with the Kolmogorov-Sinai (K-S) entropy, the standard method of calculating entropy.</AbstractText>Tissue mass reduction significantly reduces DFT when the mass reduction increases VF wavefront regularity.</AbstractText> |
3,235 | Torsade de pointes and sudden death induced by thiopental and isoflurane anesthesia in dogs with cardiac electrical remodeling. | Many anesthetic agents are known to have cardiac effects. The effects of pentobarbital, thiopental and isoflurane on dogs with electrical remodeling are lacking.</AbstractText>We studied 12 dogs that underwent two anesthesias. First, anesthesia was induced (N=12) with intravenous thiopental (17 mg/kg) induction followed by isoflurane inhalation (1.5%-3% via endotracheal tube). For electrical remodeling, we created complete atrioventricular block (CAVB) and myocardial infarction (MI). In 6 of the 12 dogs we also infused nerve growth factor (NGF) to the right stellate ganglion. All dogs had an implantable cardioverter-defibrillator (ICD) implanted. A second anesthesia was done 66 +/- 20 days later. In 8 of the 12 dogs (6 without NGF), pentobarbital was used as the only anesthetic. In the remaining 4 dogs (all with NGF), 3 received thiopental and 1 received isoflurane.</AbstractText>During the first anesthesia, none of 12 dogs had cardiac arrhythmia. During the second anesthesia, none of the 8 dogs that received pentobarbital developed ventricular fibrillation (VF). In contrast, all the dogs receiving either thiopental or isoflurane died of VF within 2 to 3 minutes. QT and P-P intervals before VF were 440 +/- 36 milliseconds and 298 +/- 28 milliseconds, longer and shorter (respectively) than those obtained the day prior to surgery (315 +/- 25 milliseconds, P < 0.001; 330 +/- 22 milliseconds, P < 0.01, respectively).</AbstractText>Thiopental and isoflurane are not arrhythmogenic in normal dogs and dogs with acute MI and CAVB, but are extremely proarrhythmic in dogs with chronic MI and CAVB. Consistent with the results of in vitro studies, pentobarbital did not induce ventricular arrhythmia in dogs with cardiac electrical remodeling.</AbstractText> |
3,236 | Case report: fibroelastoma of the papillary muscle of the mitral valve: diagnostic implications and review of the literature. | A 77-year-old woman was found accidentally to be in atrial fibrillation. Two-dimensional echocardiography revealed the presence of a mass attached to the anterior papillary muscle of the mitral valve. She was mildly symptomatic for dyspnea and asthenia. The patient was successfully operated on to excise the left ventricular mass and preserve the mitral valve apparatus. Morphological examination of the excised tissue led to a diagnosis of papillary fibroelastoma. Surgical treatment must be considered when such a tumor is diagnosed, even though asymptomatic, and especially if left-sided because of the high risk of systemic embolization. |
3,237 | Relationship between resting parameters of the mitral valve and exercise capacity in patients with mitral stenosis: can the diastolic filling period predict exercise capacity? | In order to provide patients with better exercise capacity, interventional therapy to the mitral valve is often carried out in mitral stenosis (MS). Hence, it is crucial to determine exercise capacity before deciding on the time of intervention. The study aim was to demonstrate whether resting parameters of the mitral valve, notably left ventricular diastolic filling period (LVDFP) and mitral valve resistance (MVR), relate to restricted exercise capacity.</AbstractText>Forty-six patients (30 females, 16 males; mean age 44+/-11 years; range: 33-55 years) with rheumatic MS were enrolled. Exercise capacities of patients were grouped according to NYHA classification and maximal exercise tolerance values obtained using exercise testing. Exercise capacity in male patients was quantified. Relationships between patient variables and exercise capacity were evaluated using simple linear regression analysis. In order to identify determinants of exercise capacity, a discriminate multivariate analysis was performed with variables, which were found to correlate significantly in the univariate analysis.</AbstractText>There were no correlations between echo score, MVR, planimetric mitral valve area (MVA), MVA obtained by the pressure half-time method or calculated by the continuity equation, and transmitral mean gradient and exercise capacity classes as defined by both NYHA and exercise testing. The only predictor of exercise capacity class determined by discriminate multivariate analysis using the significant parameters in the linear regression analysis was LVDFP. The quantified exercise capacity in male patients correlated only with LVDFP (r = 0.64, p = 0.008).</AbstractText>Exercise capacity cannot be predicted using routine resting parameters of the mitral valve (including MVR) in patients with MS. In this respect, the LVDFP may be of value.</AbstractText> |
3,238 | Neurohormones in mitral stenosis before and after percutaneous balloon mitral valvotomy. | The hormonal response to percutaneous balloon mitral valvotomy (PBMV) has been described in patients in sinus rhythm (SR) and with atrial fibrillation (AF). The study aim was to evaluate the effect of hemodynamic parameters and PBMV on atrial natriuretic factor (ANF) secretion and plasma renin activity (PRA) in mitral stenosis in SR and AF.</AbstractText>Thirty-one patients (26 females, five males; mean age 50.5+/-14 years) with pure rheumatic mitral stenosis underwent PBMV. Fourteen patients had AF, and 17 were in SR. PRA and ANF were measured 24 h before, and at 30 and 60 min, 24 h and one month after PBMV, after resting in a supine position for > or =2 h. Digitalis and diuretics were withdrawn 48 h before sampling; neither had patients received ACE inhibitors or beta-blockers during the previous month.</AbstractText>PBMV was successful in all cases, without complication. Mitral valve area was increased and wedge pressure decreased in both groups after PBMV. In AF patients, neither PRA nor ANF were significantly affected before and after PBMV; in SR patients, ANF was decreased and PRA increased significantly, notably 24 h after PBMV. The cardiac index was increased in both groups, but was distinctly lower in AF patients both before and after PBMV.</AbstractText>Despite similar hemodynamic results, reversal of the hormonal pattern after PBMV occurred only in SR patients, most likely because in AF patients a low cardiac index elicits a hormonal response similar to heart failure. This abnormal hormonal pattern may limit functional recovery after PBMV; hence, PBMV is best attempted while patients are still in SR.</AbstractText> |
3,239 | Eight-year experience of combined valve repair for mitral regurgitation and maze procedure. | Although atrial fibrillation (AF) is often associated with severe mitral regurgitation (MR), a simultaneous maze procedure for AF associated with repair of MR remains controversial. In this study, mid-term results of combined mitral valve repair and the maze procedure were examined.</AbstractText>Between May 1992 and April 2001, 85 patients (61 males, 24 females) underwent valve repair for MR and the maze procedure. Mean age at surgery was 61.8+/-9.1 years; mean follow up was 4.7+/-2.3 years. Valve lesions were anterior in 26 patients (31%), posterior in 31 (36%), anterior + posterior in 23 (27%), and simple dilated annulus in five (6%). Chordal replacement with expanded PTFE sutures was performed in 40 patients (47%), and leaflet resection in 41 (48%). Ring annuloplasty was also applied in 61 patients (72%). Associated procedures were tricuspid valve annuloplasty in 33 (36%), coronary artery bypass grafting in four, atrial septal defect closure in two, aortic valve repair in one, and resection of abnormal septum in the left atrium in one.</AbstractText>There was one hospital death (1%), and one late death (1%). Reopening the chest for bleeding was necessary in six cases (7%). One thromboembolic episode was detected during follow up (0.25%/patient-year). Reoperation for MR was performed in three patients (4%). Actuarial event-free survival rate was 90.0+/-6.4% at eight years. Sinus rhythm was regained in 68 patients (81%), and atrial A-wave was detected in 57 (68%) by pulsed Doppler study. Postoperative left ventricular diastolic and systolic dimensions were significantly (p = 0.001 and p = 0.017) smaller in patients who restored sinus rhythm than in those who did not (48.6+/-4.6 versus 54.6+/-4.7 mm, and 33.0+/-6.0 versus 38.1+/-6.9 mm).</AbstractText>Combined mitral valve repair for MR and the maze procedure showed satisfactory midterm results. Postoperative sinus rhythm conversion by the maze procedure may reduce left ventricular size, and the incidence of thromboembolic episodes in mitral valve repair.</AbstractText> |
3,240 | Preoperative factors predisposing to early postoperative atrial fibrillation after isolated coronary artery bypass grafting. | An analysis of 183 patients in sinus rhythm who underwent coronary artery bypass grafting was conducted to determine the association of multiple preoperative factors, including an elevated left ventricular end-diastolic pressure, with early postoperative atrial fibrillation. An association with advanced age, a history of atrial fibrillation, and preoperative digoxin use was found, but not with an elevated left ventricular end-diastolic pressure, irrespective of left ventricular systolic function. |
3,241 | Comparison of event rates and survival in patients with unexplained syncope without documented ventricular tachyarrhythmias versus patients with documented sustained ventricular tachyarrhythmias both treated with implantable cardioverter-defibrillators. | Patients with unexplained syncope and inducible ventricular tachyarrhythmias during electrophysiologic testing have an increased cardiac mortality rate. We compared event rates and survival of 178 patients with unexplained syncope and no documented ventricular arrhythmias (syncope group) versus 568 patients with documented sustained ventricular tachycardia (VT or fibrillation (VF) (VT/VF group) treated, as part of a lead (Ventritex TVL) investigation, with similar implantable cardioverter-defibrillators (ICDs) capable of extensive data storage. The 2 groups shared similar clinical characteristics. The mean follow-up was 11 months for the syncope group and 14 months for the VT/VF group. The mean time from device implantation to first appropriate therapy was similar in the 2 groups (109 +/- 140 vs 93 +/- 131 days, p = 0.40). Actuarial probability of appropriate ICD therapy was 49% and 55% at 1 and 2 years, respectively, in syncope group and 49% and 58% in VT/VF group (p = 0.57). Recurrent syncope was associated with ventricular tachyarrhythmias in 85% and 92% of the syncope group and VT/VF group, respectively (p = 0.54). At 2 years, actuarial survival was 91% in the syncope group and 93% in VT/VF group (p = 0.85). We conclude that patients treated with ICD with unexplained syncope and induced VT/VF have an equally high incidence of appropriate ICD therapy and low mortality compared with similar patients with documented VT/VF. These findings, plus the high association between recurrent syncope and ventricular arrhythmias, indicate that VT/VF are likely etiologies in selected patients with unexplained syncope and support ICD therapy in such cases. |
3,242 | Left atrial thrombus causing pulmonary embolism by passing through an atrial septal defect.<Pagination><StartPage>109</StartPage><EndPage>110</EndPage><MedlinePgn>109-10</MedlinePgn></Pagination><Abstract><AbstractText>A 66-year-old woman admitted with dyspnea on exertion had atrial fibrillation and left ventricular dysfunction. Echocardiography revealed an atrial septal defect (ASD) and a soft, easily deformable thrombus in the dilated left atrium. The atrial mass suddenly disappeared on the 10th day after admission, and contrast-enhanced chest computed tomography and pulmonary blood flow scintigraphy showed that the thrombus had detached from the left atrium, floated into the right atrium through the ASD and caused pulmonary embolism. This is the first documented case of a left atrial thrombus causing pulmonary embolism by passing through an ASD. When an ASD is present, it is important to consider not only paradoxical thromboembolism (from the right to the left atrium), but also pulmonary embolism caused by thromboembolism from the left to the right atrium.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Ishihara</LastName><ForeName>Yukako</ForeName><Initials>Y</Initials><AffiliationInfo><Affiliation>Third Department of Internal Medicine, Toho University School of Medicine, Ohashi Hospital, Tokyo, Japan.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Hara</LastName><ForeName>Hidehiko</ForeName><Initials>H</Initials></Author><Author ValidYN="Y"><LastName>Saijo</LastName><ForeName>Tomokatsu</ForeName><Initials>T</Initials></Author><Author ValidYN="Y"><LastName>Namiki</LastName><ForeName>Atsushi</ForeName><Initials>A</Initials></Author><Author ValidYN="Y"><LastName>Suzuki</LastName><ForeName>Makoto</ForeName><Initials>M</Initials></Author><Author ValidYN="Y"><LastName>Hirai</LastName><ForeName>Hironori</ForeName><Initials>H</Initials></Author><Author ValidYN="Y"><LastName>Yamaguchi</LastName><ForeName>Tetsu</ForeName><Initials>T</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>Japan</Country><MedlineTA>Circ J</MedlineTA><NlmUniqueID>101137683</NlmUniqueID><ISSNLinking>1346-9843</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000925">Anticoagulants</NameOfSubstance></Chemical><Chemical><RegistryNumber>5Q7ZVV76EI</RegistryNumber><NameOfSubstance UI="D014859">Warfarin</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000368" MajorTopicYN="N">Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D000925" MajorTopicYN="N">Anticoagulants</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001157" MajorTopicYN="N">Arterial Occlusive Diseases</DescriptorName><QualifierName UI="Q000175" MajorTopicYN="Y">diagnosis</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D017548" MajorTopicYN="N">Echocardiography, Transesophageal</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006325" MajorTopicYN="N">Heart Atria</DescriptorName><QualifierName UI="Q000002" MajorTopicYN="Y">abnormalities</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D011655" MajorTopicYN="N">Pulmonary Embolism</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D016896" MajorTopicYN="N">Treatment Outcome</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D018487" MajorTopicYN="N">Ventricular Dysfunction, Left</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014859" MajorTopicYN="N">Warfarin</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2002</Year><Month>5</Month><Day>10</Day><Hour>10</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2002</Year><Month>9</Month><Day>6</Day><Hour>10</Hour><Minute>1</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2002</Year><Month>5</Month><Day>10</Day><Hour>10</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">11999658</ArticleId><ArticleId IdType="doi">10.1253/circj.66.109</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">11998397</PMID><DateCompleted><Year>2002</Year><Month>07</Month><Day>29</Day></DateCompleted><DateRevised><Year>2015</Year><Month>11</Month><Day>19</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0031-2991</ISSN><JournalIssue CitedMedium="Print"><Issue>1</Issue><PubDate><Year>2002</Year><Season>Jan-Mar</Season></PubDate></JournalIssue><Title>Patologicheskaia fiziologiia i eksperimental'naia terapiia</Title><ISOAbbreviation>Patol Fiziol Eksp Ter</ISOAbbreviation></Journal>[Action of regulators of peripheral cholinergic processes on development of early arrhythmia in myocardial ischemic rats]. | A 66-year-old woman admitted with dyspnea on exertion had atrial fibrillation and left ventricular dysfunction. Echocardiography revealed an atrial septal defect (ASD) and a soft, easily deformable thrombus in the dilated left atrium. The atrial mass suddenly disappeared on the 10th day after admission, and contrast-enhanced chest computed tomography and pulmonary blood flow scintigraphy showed that the thrombus had detached from the left atrium, floated into the right atrium through the ASD and caused pulmonary embolism. This is the first documented case of a left atrial thrombus causing pulmonary embolism by passing through an ASD. When an ASD is present, it is important to consider not only paradoxical thromboembolism (from the right to the left atrium), but also pulmonary embolism caused by thromboembolism from the left to the right atrium.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Ishihara</LastName><ForeName>Yukako</ForeName><Initials>Y</Initials><AffiliationInfo><Affiliation>Third Department of Internal Medicine, Toho University School of Medicine, Ohashi Hospital, Tokyo, Japan.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Hara</LastName><ForeName>Hidehiko</ForeName><Initials>H</Initials></Author><Author ValidYN="Y"><LastName>Saijo</LastName><ForeName>Tomokatsu</ForeName><Initials>T</Initials></Author><Author ValidYN="Y"><LastName>Namiki</LastName><ForeName>Atsushi</ForeName><Initials>A</Initials></Author><Author ValidYN="Y"><LastName>Suzuki</LastName><ForeName>Makoto</ForeName><Initials>M</Initials></Author><Author ValidYN="Y"><LastName>Hirai</LastName><ForeName>Hironori</ForeName><Initials>H</Initials></Author><Author ValidYN="Y"><LastName>Yamaguchi</LastName><ForeName>Tetsu</ForeName><Initials>T</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>Japan</Country><MedlineTA>Circ J</MedlineTA><NlmUniqueID>101137683</NlmUniqueID><ISSNLinking>1346-9843</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000925">Anticoagulants</NameOfSubstance></Chemical><Chemical><RegistryNumber>5Q7ZVV76EI</RegistryNumber><NameOfSubstance UI="D014859">Warfarin</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000368" MajorTopicYN="N">Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D000925" MajorTopicYN="N">Anticoagulants</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001157" MajorTopicYN="N">Arterial Occlusive Diseases</DescriptorName><QualifierName UI="Q000175" MajorTopicYN="Y">diagnosis</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D017548" MajorTopicYN="N">Echocardiography, Transesophageal</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006325" MajorTopicYN="N">Heart Atria</DescriptorName><QualifierName UI="Q000002" MajorTopicYN="Y">abnormalities</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D011655" MajorTopicYN="N">Pulmonary Embolism</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D016896" MajorTopicYN="N">Treatment Outcome</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D018487" MajorTopicYN="N">Ventricular Dysfunction, Left</DescriptorName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014859" MajorTopicYN="N">Warfarin</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2002</Year><Month>5</Month><Day>10</Day><Hour>10</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2002</Year><Month>9</Month><Day>6</Day><Hour>10</Hour><Minute>1</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2002</Year><Month>5</Month><Day>10</Day><Hour>10</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">11999658</ArticleId><ArticleId IdType="doi">10.1253/circj.66.109</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">11998397</PMID><DateCompleted><Year>2002</Year><Month>07</Month><Day>29</Day></DateCompleted><DateRevised><Year>2015</Year><Month>11</Month><Day>19</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0031-2991</ISSN><JournalIssue CitedMedium="Print"><Issue>1</Issue><PubDate><Year>2002</Year><Season>Jan-Mar</Season></PubDate></JournalIssue><Title>Patologicheskaia fiziologiia i eksperimental'naia terapiia</Title><ISOAbbreviation>Patol Fiziol Eksp Ter</ISOAbbreviation></Journal><ArticleTitle>[Action of regulators of peripheral cholinergic processes on development of early arrhythmia in myocardial ischemic rats].</ArticleTitle><Pagination><StartPage>14</StartPage><EndPage>16</EndPage><MedlinePgn>14-6</MedlinePgn></Pagination><Abstract>Occlusion of the left coronary artery in rats provoked ventricular tachycardia (VT) and ventricular fibrillation (VF) within the first 30 min of ischemia leading to death in 20% animals. Methacin (i.v., 100 micrograms/kg) significantly prolonged VT and VF without effects on the survival. Acetylcholine (i.v., 10 micrograms/kg/min) had no influence on VT frequency and severity but prevented VF. Rats from this group survived. The same effect was observed for neostigmine (i.v., 25 micrograms/kg). Nicotine (i.v., 2.5 micrograms/kg/min) prolonged VT episode duration but did not change frequency and severity of VF and survival. Ganglioblockers hexametony and azametony (i.v., both in a dose 500 micrograms/kg) significantly attenuated VT, prevented VF and death of the animals. Thus, cholinotropic drugs may have both antiarrhythmic and proarrhythmogenic effects in early arrhythmias induced by ischemia. |
3,243 | [Stress cine MRI for detection of coronary artery disease]. | Stress testing is the cornerstone in the diagnosis of patients with suspected coronary artery disease (CAD). Stress echocardiography has become a well-established modality for the detection of ischemia-induced wall motion abnormalities. However, display and reliable interpretation of stress echocardiography studies are user-dependent, the test reproducibility is low, and 10 to 15 % of patients yield suboptimal or non-diagnostic images. Due to its high spatial and contrast resolution, MRI is known to permit an accurate determination of left ventricular function and wall thickness at rest. Early stress MRI studies provided promising results with respect to the detection of CAD. However, the clinical impact was limited due to long imaging time and problematic patient monitoring in the MRI environment. Recent technical improvements - namely ultrafast MR image acquisition - led to a significant reduction of imaging time and improved patient safety. Stress can be induced by physical exercise or pharmacologically by administration of a beta1-agonist (dobutamine) or vasodilatator (dipyridamole and adenosine). The best developed and most promising stress MRI technique is a high-dose dobutamine/atropine stress protocol (10, 20, 30, 40 microgram/kg/min; optionally 0.25-mg fractions of atropine up to maximal dose 1 mg). Severe complications (myocardial infarction, ventricular fibrillation and sustained tachycardia, cardiogenic shock) may be expected in 0.25 % of patients. Currently, data of three high-dose dobutamine stress MRI studies are available, revealing a good sensitivity (83 - 87 %) and specificity (83 - 86 %) in the assessment of CAD. The direct comparison between echocardiography and MRI for the detection of stress-induced wall motion abnormalities yielded better results for dobutamine-MRI in terms of sensitivity (86.2 % vs. 74.3 %; p < 0.05) and specificity (85.7 % vs. 69.8 % p < 0.05) as compared to dobutamine stress echocardiography. The superior results of MRI can mainly be explained by the better image quality with sharp delineation of the endocardial and epicardial borders. Currently, stress MRI is already a realistic clinical alternative for the non-invasive assessment of CAD in patients with impaired image quality in echocardiography. |
3,244 | Atrial fibrillation recurrence after internal cardioversion: prognostic importance of electrophysiological parameters. | To evaluate the clinical and electrophysiological determinants of arrhythmia recurrence in patients undergoing internal atrial cardioversion for chronic atrial fibrillation (AF).</AbstractText>Tertiary cardiac referral centre.</AbstractText>101 consecutive patients with failed external cardioversion or AF > or = 1 year underwent internal atrial cardioversion; once stable sinus rhythm (SR) was obtained, electrophysiological study was performed in 73 patients (72%) who gave informed consent. Patients were then followed on antiarrhythmic treatment.</AbstractText>101 consecutive patients underwent internal atrial cardioversion in the period 1996-1999 with 100% conversion to SR; prophylactic antiarrhythmic treatment was flecainide (52%), amiodarone (37%), and sotalol (11%). Average follow up at first AF recurrence was 18.4 (14.4) months (range 0.1-49.8 months); persistence of SR was observed in 72/101 (72%) patients. By logistic regression, AF duration (odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01 to 1.13) and a lower sinus rate at discharge on antiarrhythmic drugs (OR 0.92, 95% CI 0.85 to 0.99) were independent predictors of AF recurrence, whereas age, New York Heart Association functional class, left atrial dimensions, and left ventricular ejection fraction were not predictive of arrhythmia recurrence. When electrophysiological parameters were added to the statistical model in 73 patients, a shorter atrial effective refractoriness (OR 1.04, 95% CI 1 to 1.08) and an abnormal relation of atrial effective refractoriness to cycle length (OR 31, 95% CI 3.7 to 266) were also independent predictors of AF recurrence at follow up, beyond AF duration and heart rate at discharge.</AbstractText>Patients with failed external cardioversion or long lasting AF may benefit from internal atrial cardioversion and antiarrhythmic treatment to keep SR at long term; electrophysiological study may identify patients at the highest risk of arrhythmia recurrence. Although preservation of SR seems unlikely for AF duration > 3 years, a consistent minority of this subgroup (38%) may benefit from this approach.</AbstractText> |
3,245 | Implantable cardioverter-defibrillators in arrhythmias: a rapid and systematic review of effectiveness. | To review the effectiveness of implantable cardioverter-defibrillators (ICDs) in the management of risk factors for sudden cardiac death.</AbstractText>Systematic review of randomised controlled trials identified from searching eight electronic databases, bibliographies of relevant studies, and consulting experts.</AbstractText>Absolute and relative reduction in mortality.</AbstractText>Seven trials met the inclusion criteria. These showed changes in absolute risk of total mortality ranging from +1.7% to -22.8% (relative risk reductions -7% to +54%). Estimated benefits from ICD treatment compared with conventional drug treatment at three years were 0.23 to 0.80 additional years of life.</AbstractText>Evidence suggests that ICDs reduce total mortality in particular subgroups of patients at high risk of ventricular arrhythmias. The optimal strategy for identifying the patients who could benefit most is not clearly established. Ongoing trials into the treatment of cardiac failure with ICDs may provide further evidence about subgroups in whom ICDs are most cost effective.</AbstractText> |
3,246 | Vasopressin in cardiovascular patients: therapeutic implications. | Vasopressin is a vital homeostatic protein which regulates fluid balance via its antidiuretic effects and vascular tone via its vasoconstrictive effects. Endogenous vasopressin deficiency has been implicated in several disease states resulting in vasodilatory shock. In particular, vasopressin levels are low in patients following cardiac surgery and in those with ventricular dysrhythmias. Several recent studies have demonstrated the effectiveness of exogenous vasopressin in providing haemodynamic support in patients with postcardiopulmonary bypass vasodilatory shock and refractory ventricular fibrillation. This manuscript reviews the pathophysiological and clinical basis for vasopressin replacement in patients with cardiovascular collapse. |
3,247 | Simple surgical isolation of pulmonary veins for treating secondary atrial fibrillation in mitral valve disease. | Chronic atrial fibrillation (AF) due to mitral valve disease has been successfully treated by surgery. We performed a study to evaluate the effectiveness of a surgical method of simple pulmonary vein isolation (PVI) without radiofrequency or cryoablation in the restoration of sinus rhythm in a group of patients.</AbstractText>Fifteen patients were operated on for mitral valve disease and chronic AF. The technique consists basically of a circumferential incision excluding the pulmonary vein ostia from the left atrium.</AbstractText>Sinus rhythm was achieved in 92.3% of the patients at 6-month follow-up. Echocardiograms 2 months after surgery showed a mean decrease of 1.1 cm in left atrial size. Effective atrial ejection was reestablished in all patients in whom sinus rhythm was achieved (mean LA ejection fraction 41% +/- 14%). Twenty-four hour Holter recordings did not show episodes of paroxysmal atrial fibrillation in any patients. Four patients had isolated episodes of ventricular ectopic beats. Stress electrocardiograms showed mean maximal ventricular response was 64% +/- 11% and 73% +/- 9% of predicted value at 2 and 6 months, respectively. All patients had improved NYHA functional class after surgery; 74% of patients were in NYHA functional class I at 6 months compared with 13.3% preoperatively.</AbstractText>Pulmonary vein isolation without the use of radiofrequency or cryoablation is effective in restoring sinus rhythm in patients with chronic AF secondary to mitral valve disease. Based on simple surgical incisions, this technique is more advantageous than others requiring additional instrumentation.</AbstractText> |
3,248 | Ventricular assist device support for management of sustained ventricular arrhythmias. | We describe herein the cases of 2 patients who had ventricular arrhythmias. In one, a short-term biventricular assist device, the ABIOMED BVS 5000, was placed because the patient had sustained ventricular tachycardia and could not be weaned from cardiopulmonary bypass. Excellent hemodynamic support was maintained for several days while the antiarrhythmic therapy was maximized. Sinus rhythm was restored, and the patient was successfully weaned from the ventricular assist device. However, the substrate for the arrhythmia persisted, and a recurrence, 1 week later, resulted in the patient's death. In the 2nd patient, the use of an implantable left ventricular assist device was successful in temporarily alleviating the ventricular tachycardia associated with ischemic cardiomyopathy. However, after 2 days of device assistance, the patient experienced a recurrence of the tachycardia, which degenerated into ventricular fibrillation with a marked deterioration in the patient's hemodynamics. The arrhythmia persisted despite multiple attempts at external cardioversion, and internal cardioversion and placement of an automatic implantable cardioverter-defibrillator were necessary. This treatment, along with repeated boluses of amiodarone, led to successful suppression of the arrhythmias, and the patient eventually underwent transplantation. The mechanical hemodynamic support of the circulation by ventricular assist devices was effective in supporting these 2 patients who had sustained ventricular arrhythmias. |
3,249 | [The use of arginine vasopressin during cardiopulmonary resuscitation. An analysis of experimental and clinical experience and a view of the future]. | The risks and benefits of epinephrine given during cardiopulmonary resuscitation (CPR) are controversially discussed. Animal experiments revealed beta-receptor-mediated adverse effects of epinephrine such as increased myocardial oxygen consumption, ventricular arrhythmia, ventilation-perfusion defects, and cardiac failure in the postresuscitation phase. In clinical studies, high-dose vs. standard-dose epinephrine was unable to improve resuscitation success. During CPR in patients, endogenous arginine vasopressin (AVP) levels were increased and surviving vs. non-surviving patients had significantly higher AVP levels. This may indicate that the human body discharges AVP during life-threatening situations as an additional vasopressor to catecholamines in order to maintain cardiocirculatory homeostasis. In different experimental CPR models, AVP compared with epinephrine given during CPR significantly improved vital organ blood flow, coronary perfusion pressure, resuscitability, and long-term survival. During prolonged CPR with repeated drug administration, AVP but not epinephrine maintained coronary perfusion pressure on a level that ensured return of spontaneous circulation. Also, AVP can be administered successfully in the intravenous dose into the endobronchial tree, and also intraosseously. When given during CPR, AVP induces a transient splanchnic hypoperfusion, and an increase in systemic vascular resistance, both of which normalized spontaneously; furthermore, an oligo-anuric state was not observed. In two clinical studies, AVP vs. epinephrine improved 24-h survival during out-of-hospital CPR, and comparable CPR outcome during in-hospital CPR. The new CPR guidelines of both the American Heart Association and the European Resuscitation Council assign a given CPR intervention into classes of recommendation [class 1 (definitely recommended), class 2 A (intervention of choice), class 2B (alternative intervention), class X (neutral), or class 3 (not recommended)]. For CPR of adults with shock-refractory ventricular fibrillation, 40 units AVP or 1 mg epinephrine is recommended (class 2B); patients with asystole or pulseless electrical activity should be resuscitated with epinephrine. AVP is not recommended for adult cardiac arrest patients with asystole or pulseless electrical activity; or pediatric cardiac arrest patients due to a lack of clinical data. Until definitive data about AVP vs. epinephrine effects during CPR are available, the present state of knowledge should be interpreted that two vasopressors are available for use instead of one. |
3,250 | Echocardiographic findings in a contemporary Afro-Caribbean population referred for evaluation of atrial fibrillation or flutter. | Atrial fibrillation and/or flutter is the most common and the most significant cardiac arrhythmia in the Caribbean. This study is an attempt to determine the echocardiographic findings in a current, consecutive series of Afro-Caribbean patients referred for evaluation of atrial fibrillation and flutter. Between May 1998 and June 2000, 50 patients (mean age 67 years, 58% male) had echocardiograms done. Measurements included left atrial dimension (LA), left ventricular end-systolic dimension (LVESD), LV end-diastolic dimension (LVEDD), LV posterior wall thickness (LVPWT) and ventricular septal thickness (VST). Left ventricular ejection fraction (EF) was calculated. LA > 4 cm, LVPWT or VST > 13 mm, and LVEF < 50% were considered abnormal. Atrial fibrillation was seen in 92%, atrial flutter in 8%; 60% were chronic, 40% paroxysmal; 56% had congestive heart failure. The most frequent echocardiographic finding was LV hypertrophy (19/50, 38%). Left ventricular systolic dysfunction was present in 12/50, 24% (25% with LV hypertrophy also). Valvular disease (abnormal appearing valve, no Doppler study), was seen in 9/50, 18%. Normal findings ("lone atrial fibrillation") were seen in 10/50, 20%. Increased LA dimension was seen in 39/50, 78%. Patients with lone atrial fibrillation were younger (mean 56 years) than those with valvular disease (mean 64 years), LV systolic dysfunction (mean 69 years) and those with LV hypertrophy (mean 72 years). Thus, LV hypertrophy, probably secondary to hypertension, is the most frequent echocardiographic finding, with LV dysfunction (such as seen in coronary artery disease) seen less often. Valvular disease and lone atrial fibrillation rates are similar to rates in developed countries. |
3,251 | Dual site right atrial pacing in the prevention of symptomatic atrial fibrillation refractory to drug therapy and unrelated to sinus bradycardia. | Dual-site right atrial pacing has been shown recently to prevent atrial fibrillation relapses in patients affected by drug-refractory, highly-recurring tachyarrhythmia, associated to sinus bradycardia. The aim of our study was to verify whether this stimulation modality could be useful in patients affected by refractory atrial fibrillation unassociated to sinus bradycardia.</AbstractText>Fifteen patients (6 males) affected by refractory, symptomatic atrial fibrillation, and potential candidates to AV node ablation, were prospectively enrolled. Mean age was 65 +/- 5 years (range 62-78). Associated pathology was arterial hypertension in 12, and dilated cardiomyopathy in 3. Eight patients were affected by persistent atrial fibrillation, and seven by paroxysmal atrial fibrillation. The duration of the arrhythmia was 61 +/- 63 months (range 3-216). Left atrial diameter was 39.4 +/- 4.2 mm (range 33-46), left ventricular end-diastolic diameter was 52.4 +/- 12.2 mm (range 41-90), and left ventricular ejection fraction was 55 +/- 16 (range 18-81). Single chamber atrial pacing was used in 10 patients, dual chamber in 5 patients. The mean duration of follow up was 24 +/- 12 months (range 3-41). During this period the number of episodes of atrial fibrillation decreased from a mean of 13 +/- 38 (range 1-150) to 0.4 +/- 0.7 (range 0-2.3) per month (p < 0.001). In the subgroup of patients with persistent atrial fibrillation the number of episodes decreased from a mean of 20.4 +/- 52.4 (range 1-150) to 0.6 +/- 0.9 (range 0-2.3) (p < 0.001). In patients with paroxysmal atrial fibrillation the number of episodes decreased from 4.6 +/- 3.5 (range 2-12) to 0.2 +/- 0.5 (range 0-1.4) (p < 0.001). One patient (6.7%) developed chronic atrial fibrillation 16 months after the implant, 2 remaining patients (13%) had their arrhythmia unaltered. After the implant the number of Class 1 antiarrhythmic drugs fell from 18 to 6 (p < 0.001) and that of Class 2 changed from 0 to 7 p < 0.001). The use of Class 3 and 4 did not change significantly. No complications related to implant were observed.</AbstractText>Permanent dual-site right atrial pacing can prevent atrial fibrillation recurrences in patients affected by highly symptomatic episodes unassociated to sinus bradycardia.</AbstractText> |
3,252 | Brugada syndrome: a case report of an unusual association with vasospastic angina and coronary myocardial bridging. | This report describes a case of an unusual association between vasospastic angina, coronary myocardial bridging, and Brugada syndrome. The patient complained of chest pain followed by rhythmic palpitation and syncope. Brugada syndrome ECG markers were documented with transient ST-segment elevation in lateral leads. A coronary angiogram showed a myocardial bridging in the left anterior descending artery and coronary vasospasm was reproduced after intracoronary ergonovine injection in the circumflex coronary artery. Ventricular fibrillation was induced by programmed electrical stimulation. The described association can be important because interaction between ischemia and Brugada syndrome electrophysiological substrate could modulate individual susceptibility to life-threatening ventricular tachyarrhythmias. |
3,253 | Intoxication with taxus baccata: cardiac arrhythmias following yew leaves ingestion. | The use of yew leaves (Taxus Baccata) as a means of deliberate self-harm is infrequent. The potent effect of the toxin is primarily cardiac and results in rhythm alterations and ultimately ventricular fibrillation. As there is no known antidote, and classic antiarrhythmic therapy proves to be ineffective, a prompt diagnosis is of great importance as immediate supportive action is the only valuable alternative. This case describes a 43-year-old women who attempted suicide by ingesting the leaves of Taxus Baccata. We discuss the effects and the difficulty of treatment associated with yew leaf poisoning. |
3,254 | Adenosine induced ventricular fibrillation in Wolff-Parkinson-White syndrome. | VF was observed in four patients (group A) with preexcited AF presenting to the emergency department who had been given 12 mg of adenosine. These patients were resuscitated and underwent electrophysiological study and catheter ablation of the accessory pathway (AP). In a control (group B) of five patients with manifest AP, sustained AF was induced by rapid atrial pacing during electrophysiological study and 12 mg of adenosine was administered. The ECG and electrophysiologic features in the two groups were compared. All patients had a single manifest AP. In group A, three patients had a left free-wall AP and one patient had a posteroseptal AP, while in the control group all had left free-wall APs. The antegrade AP effective refractory period (ERP) in groups A and B was 227 +/- 29 and 289 +/- 37 ms, respectively (P < 0.05). The atrial ERP was 210 +/- 17 versus 219 +/- 21 ms, respectively, in groups A and B (P > 0.05). The shortest R-R interval during AF in group A was 246 +/- 51 ms and 301 +/- 60 ms in group B (P value < 0.05). After adenosine, no patient in group B developed VF. Adenosine may cause VF when administered during preexcited AF. This phenomenon is seen in patients having APs with short refractory periods. |
3,255 | Site of the arrhythmogenic focus and cardiac vulnerability to ventricular fibrillation. | The aim of this study was to test the hypothesis that a subendocardial arrhythmogenic focus makes the heart more susceptible to VF due to electrical interaction with the Purkinje network. Monofocal ventricular tachycardia (mVT) was created by injecting 5-microg aconitine into the left ventricular subepicardium (EPI-mVT, n = 8) or subendocardium (ENDO-mVT, n = 13) in anesthetized dogs. Despite the similar cycle length of mVT, the incidence of VF was significantly different between EPI-mVT and ENDO-mVT (100 [8/8] vs 46% [6/13], P <0.05). VF was invariably preceded by hemodynamic deterioration. Three-dimensional cardiac mapping (n = 10, 221 +/- 11 recording sites) revealed that VF was triggered solely by focal firing unrelated to the primary arrhythmogenic focus in both mVT models. No interaction between the primary focus and adjacent endocardial tissue was indicated. These results suggest that the proximity of the arrhythmogenic focus to the Purkinje network has little role in cardiac vulnerability to VF, and that progression of mVT to VF is largely caused by sporadic focal firing regardless of the site of the arrhythmogenic focus in the present animal model. |
3,256 | Clinical predictors of defibrillation thresholds with an active pectoral pulse generator lead system. | Active pectoral pulse generators are used routinely for initial ICD placement because they reduce DFTs and simplify the implantation procedure. Despite the common use of these systems, little is known regarding the clinical predictors of defibrillation efficacy with active pulse generator lead configurations. Such predictors would be helpful to identify patients likely to require higher output devices or more complicated implantations. This was a prospective evaluation of DFT using a uniform testing protocol in 102 consecutive patients with an active pectoral can and dual coil transvenous lead. For each patient, the DFT was measured with a step-down protocol. In addition, 34 parameters were assessed including standard clinical echocardiographic and radiographic measures. Multivariate stepwise regression analysis was performed to identify independent predictors of the DFT. The mean DFT was 9.3 +/- 4.6 J and 93% (95/102) of patients had a DFT < or = 15 J. The QRS duration, interventricular septum thickness, left ventricular mass, and mass index were significant but weak (R < 0.3) univariate predictors of DFT. The left ventricular mass was the only independent predictor by multivariate analysis, but this parameter accounted for < 5% of the variability of DFT measured (adjusted R2 = 0.047, P = 0.017). The authors concluded that an acceptable DFT (< 15 J) is observed in > 90% of patients with this dual coil and active pectoral can lead system. Clinical factors are of limited use for predicting DFTs and identifying those patients who will have high thresholds. |
3,257 | Transient proarrhythmic state following atrioventricular junctional radiofrequency ablation. | This study was designed to prospectively assess ventricular de- and repolarization by the QRS, QT, and JT intervals, and their dispersion in the 12-lead ECG during right ventricular pacing at 60, 70, and 80 beats/min during the first month after AV junctional RF ablation. Previous reports have found early polymorphic ventricular arrhythmia after RF AV junctional ablation. Our hypothesis was that there is a proarrhythmic state following this procedure, which depends on the paced rate and time after ablation. The analysis of the immediate changes was based on 17 patients (10 men) with a mean age of 64 years (SD 14) (range 38-82 years). A 12-lead ECG was recorded during right ventricular pacing at 60, 70, and 80 beats/min within 24 hours (day 1), between 24 and 48 hours (day 2), and 1 week after ablation (day 7). For analysis of changes beyond 1 week, 13 additional patients with a mean age of 73 years (SD 8) (range 62-90 years) were analyzed on days 1, 7, and 30. All intervals were measured with a digitizing table. The mean QRS duration shortened by 2.4% at 60 beats/min (P <0.01), and the mean QT and JT intervals shortened by 5-7% between days 1 and 7 (P < 0.001). The mean QT was 9% shorter and the mean JT interval was 13% shorter at 80 compared to 60 beats/min on day 1 (P < 0.001). QT dispersion was reduced by 13% when the stimulation rate was increasedfrom 60 to 80 beats/min on day 1 (P < 0.05). There were no significant changes beyond the first week. The study results point to the induction of a proarrhythmic state immediately after AV junctional RF ablation resolving during the first week. Repolarization shortened gradually between 80 and 60 beats/min to an extent that is suggestive of a clinically important antiarrhythmic effect at the higher rate, which was supported also by clinical experience. |
3,258 | Rapid pacing results in changes in atrial but not in ventricular refractoriness. | It is well known that atrial tachycardia causes atrial electrical remodeling, characterized by shortening of atrial effective refractory periods (AERPs) and loss of physiological adaptation of AERP to rate. However, the nature and time course of changes in ventricular effective refractory periods (VERP) caused by rapid rates are to be established. After being instrumented with epicardial electrodes on both atria and both ventricles nine goats were subjected to 1 week of rapid AV pacing with a rate of 240 beats/min and an AV delay of 100 ms. Pacing was only interrupted for measurement of left and right AERPs and VERPs at three basic cycle lengths (BCL) of 400 ms, 300 ms, and 200 ms during sinus rhythm in the conscious animal. Left and right AERPs decreased at all BCLs, reaching minimum values after 3 days (right AERP at BCL of 400 ms, 96 +/- 16 ms after 3 days vs 144 +/- 16 ms at baseline, P < 0.05). In contrast, both left and right VERPs did not change at any BCL. This study demonstrates a difference between the atria and ventricles with respect to tachycardia induced changes in refractoriness. |
3,259 | High survival in out-of-hospital cardiopulmonary resuscitation--7 years' incidence according to the Utstein template in a small town in Northern Norway. | Core data according to the Utstein template was compiled from all out-of-hospital resuscitations in the city of Bodø, Northern Norway, over 7 years (1992-98). Out of a population of 34,500, 149 resuscitations were attempted. A cardiac aetiology was present in 123 patients and their median age was 72.1 years. Eighteen of the 96 patients having suffered a witnessed arrest of cardiac origin were alive after 1 year (18.8%). Fifteen had the best cerebral performance score (scale 1-5) and three had a score of 2. Survival among all resuscitated patients (149) was 18.8% also, giving a number of 62 attempted resuscitations and 11.2 survivors per 100,000 inhabitants per year, respectively. Thirty-three per cent of witnessed cardiac arrests with ventricular fibrillation or ventricular tachycardia survived to discharge, but only 7% with asystole. When the arrest was witnessed, median response time was 5 minutes, and was 3 minutes for the survivors. To our knowledge, this is the highest survival of out-of-hospital arrests in Scandinavia reported so far, and is chiefly explained by short turnout distances. |
3,260 | Predictors of appropriate implantable cardioverter-defibrillator therapy in patients with idiopathic dilated cardiomyopathy. | Evaluating predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy in patients with idiopathic dilated cardiomyopathy (IDC) may be helpful in developing risk stratification strategies for these patients. Fifty-four patients with IDC underwent ICD implantation and were followed up. Twenty-three patients (42%) had a class I indication for ICD implantation; the remaining patients underwent implantation for multiple risk factors for sudden death including left ventricular dysfunction, nonsustained ventricular tachycardia, syncope, or positive electrophysiologic study results. Clinical, electrocardiographic, and electrophysiologic data were collected. Appropriate ICD therapy was defined as an antitachycardia pacing therapy or shock for tachyarrhythmia determined to be either ventricular tachycardia or ventricular fibrillation. Appropriate ICD therapy was observed in 23 patients (42%). There was a significant difference in use of beta-blocker therapy between patients who did and did not have appropriate ICD therapy (p <0.0003). Cox regression analysis identified the following univariate predictors (p <0.1): class I indication (p <0.005) and lack of use of beta-blocker therapy (p <0.0007). In multivariate analysis, only lack of beta-blocker use (relative risk 0.15, 95% confidence intervals 0.05 to 0.45; p <0.0007) was identified as a predictor of appropriate ICD therapy. Of the patients who received ICD therapy, only 4 (17%) were taking beta blockers, whereas 21 of the 31 patients (68%) who did not receive ICD therapy were treated with beta blockers (p <0.0003). In patients with IDC selected for ICD implantation, the most consistent predictor of appropriate ICD therapy was lack of beta-blocker use. Attempts should be made to administer beta blockers to these patients, if tolerated. |
3,261 | [Successful RF ablation in a patient with paroxysmal atrial fibrillation induces by atrioventricular nodal reentrant tachycardia]. | We describe a case of 47-year old patient with frequent episodes of paroxysmal atrial fibrillation (PAF) with fast ventricular rate. During electrophysiological study an atrioventricular nodal reentrant tachycardia (AVNRT) was diagnosed with rapid degeneration into atrial fibrillation. Successful RF ablation of slow pathway was performed. There were no PAF recurrences during six months follow-up. |
3,262 | Percutaneous aortic valve replacement: an experimental study. I. Studies on implantation. | The purpose of this preliminary study was to devise a new surgical procedure for minimally invasive aortic valve implantation with a transluminal technique.</AbstractText>The new collapsible heart valve was prepared by mounting a porcine aortic valve, taken from a freshly slaughtered pig, into a self-expandable nitinol stent by means of a suture technique. The outer diameter of the valved stent ranged from 15 to 23 mm, and the length ranged from 21 to 28 mm. Before implantation in vivo, these valved stents were tested in an in vitro circulatory system. Only in vitro-tested valved stents with a pressure gradient of less than 7 mm Hg and regurgitation of I degrees or less were used for transluminal aortic valve implantation in vivo. Six of these valved stents were implanted in the descending aorta and 8 in the ascending aorta of anesthetized pigs. The catheter delivery system (22F) was extraperitoneally inserted through the left iliac artery or the infrarenal aorta. Measurements for transvalvular gradient, valvular opening and closure, blood-flow characteristics, regurgitation, and macroscopic analysis were performed at baseline and after the observation period (164 +/- 48 minutes).</AbstractText>This preliminary study contained 14 animals. One animal died of ventricular fibrillation. Technical failure occurred in 2 pigs as a result of stent twisting. At the end of the observation period, the 11 successfully implanted valved stents demonstrated low transvalvular gradients (mean end-systolic Deltarho(max) of 5.4 +/- 3.3 mm Hg for the descending aorta group, 5.4 +/- 1.2 mm Hg for the supracoronary group, and 5.4 +/- 1.1 mm Hg for the subcoronary group), which did not differ from their in vitro gradients. Two-dimensional echocardiography demonstrated complete valvular closure and opening in 5 of 5 cases. Angiography indicated only a physiologic jet of regurgitation (0 degrees ) in 8 animals and mild (I degrees ) regurgitation in 3 animals. Color Doppler ultrasonography indicated no regurgitation in 5 of 5 cases and minor paravalvular leakage in 1 case.</AbstractText>Aortic valved stents can be successfully implanted without thoracotomy by using a transluminal catheter technique. Long-term function of the valves remains to be established.</AbstractText> |
3,263 | Doppler echocardiographic assessment of left ventricular filling pressures in elderly patients with moderate/severe aortic stenosis. | Doppler-derived mitral inflow indices reflect left ventricular (LV) filling pressures but often vary with age. Diastolic filling is impaired in LV pressure overload states. The objective of this study was to determine the influence of age on the relationship between mitral inflow indices and LV filling pressures in patients with aortic stenosis. The authors studied 57 consecutive patients (age, 77 years; 52% male) with moderate to severe aortic stenosis (aortic valve area < or =1.0 cm(2)) on cardiac catheterization and echocardiographic studies performed within 48 hours of catheterization. Patients with atrial fibrillation, aortic insufficiency, mitral stenosis, and paced rhythm were excluded. Echocardiographic variables obtained from five cardiac cycles were: E/A ratio and deceleration time (DT). Patients were subclassified by age (< and > or =75 years), ejection fraction ([EF] < and > or =50%), and coronary artery disease (CAD). Pulmonary capillary wedge pressure (PCWP) correlated with DT (r=-0.86; p=0.001) and with E/A (r=0.7; p=0.001) more strongly than did LV end-diastolic pressure. Age did not alter the relationship between DT and PCWP (r=-0.92; p=0.001 for < 75 years vs. r=-0.83; p=0.001 for > or =75 years). PCWP was predicted by the equation PCWP=-0.10DT+43, regardless of age. EF also had little influence on the correlation between PCWP and DT (r=-0.80; p=0.001 for EF < 50% vs. r=-0.94; p=0.001 for EF > or =50%). Similarly, there were no significant differences between the regression equations and correlations between the CAD and no-CAD groups: for CAD patients, PCWP=41.8-0.10DT; p < 0.0001; r=-0.84 (p < 0.0001). For no-CAD subjects, PCWP=46.2-0.12DT; p < 0.0001; r=20.92 (p < 0.0001). In patients with significant aortic stenosis, DT correlated strongly with PCWP but not with LV end-diastolic pressure. This relationship was independent of age, CAD, or EF. |
3,264 | Reduced risk of sudden death from chest wall blows (commotio cordis) with safety baseballs. | In an experimental model of sudden death from baseball chest wall impact (commotio cordis), we sought to determine if sudden death by baseball impact could be reduced with safety baseballs.</AbstractText>Sudden cardiac death can occur after chest wall impact with a baseball (commotio cordis). Whether softer-than-standard (safety) baseballs reduce the risk of sudden death is unresolved from the available human data. In a juvenile swine model, ventricular fibrillation (VF) has been shown to be induced reproducibly by precordial impact with a 30-mph baseball 10 to 30 ms before the T-wave peak, and this likelihood was reduced with the softest safety baseballs (T-balls). To further test whether safety baseballs would reduce the risk of sudden death at velocities more relevant to youth sports competition, we used our swine model of commotio cordis to test baseballs propelled at the 40-mph velocity commonly attained in that sport.</AbstractText>Forty animals received up to 3 chest wall impacts at 40 mph during the vulnerable period of repolarization for VF with 1 of 3 different safety baseballs of varying hardness, and also by a standard baseball.</AbstractText>Safety baseballs propelled at 40 mph significantly reduced the risk for VF. The softest safety baseballs triggered VF in only 11% of impacts, compared with 19% and 22% with safety baseballs of intermediate hardness, and 69% with standard baseballs.</AbstractText>In this experimental model of low-energy chest wall impact, safety baseballs reduced (but did not abolish) the risk of sudden cardiac death. More universal use of these safety baseballs may decrease the risk of sudden death on the playing field for young athletes.</AbstractText> |
3,265 | Clinical value of left atrial appendage flow for prediction of long-term sinus rhythm maintenance in patients with nonvalvular atrial fibrillation. | This study evaluated the role of various clinical and echocardiographic parameters, including the left atrial appendage (LAA) anterograde flow velocity, for prediction of the long-term preservation of sinus rhythm (SR) in patients with successful cardioversion (CV) of nonvalvular atrial fibrillation (AF).</AbstractText>Echocardiographic parameters for assessing long-term SR maintenance after successful CV of nonvalvular AF are not accurately defined.</AbstractText>Clinical, transthoracic echocardiographic and transesophageal echocardiographic (TEE) data--measured in AF lasting >48 h--of 186 consecutive patients (116 men, mean age: 65 +/- 9 years) with successful CV (electrical or pharmacologic) were analyzed for assessment of one-year maintenance of SR.</AbstractText>At one-year follow-up, 91 of 186 (49%) patients who underwent successful CV continued to have SR. Mean LAA peak emptying flow velocity was higher in patients remaining in SR for one year than in those with AF relapse (41.7 +/- 20.2 cm/s vs. 27.7 +/- 17.0 cm/s; p < 0.001). On multivariate logistic regression analysis, only the mean LAA peak emptying velocity >40 cm/s (p = 0.0001; chi(2): 23.9, odds ratio [OR] = 5.2, confidence interval [CI] 95% = 2.7 to 10.1) and the use of preventive antiarrhythmic drug treatment (p = 0.0398; chi(2): 4.2; OR = 2.0, CI 95% = 1.0 to 3.8) predicted the continuous preservation of SR during one year, outperforming other univariate predictors such as absence of left atrial spontaneous echocardiographic contrast during TEE, the left atrial parasternal diameter <44 mm, left ventricular ejection fraction >46% and AF duration <1 week before CV. The negative and positive predictive values of the mean LAA peak emptying velocity >40 cm/s for assessing preservation of SR were 66% (CI 95% = 56.9 to 74.2) and 73% (CI 95% = 62.4 to 83.3), respectively.</AbstractText>In TEE-guided management of nonvalvular AF, high LAA flow velocity identifies patients with greater likelihood to remain in SR for one year after successful CV. Low LAA velocity is of limited value in identifying patients who will relapse into AF.</AbstractText> |
3,266 | The renin-angiotensin system does not contribute to the endothelial dysfunction and increased infarct size in rats exposed to second hand smoke. | Both second hand smoke (SHS) and the renin-angiotensin system (RAS) contribute to endothelial dysfunction and increased infarct size in a rat ischaemia-reperfusion model. However, the potential interaction between SHS and the RAS is unknown.</AbstractText>Eighty-four rats were randomised into four groups: group C was a normal control; L was given 40 mg/kg/day of losartan in drinking water; SC and SL were exposed to SHS (smoking chamber) and given regular water or 40 mg/kg/day of losartan in drinking water, respectively. After six weeks of pre-treatment, rats were subjected to 17 minutes of left coronary artery occlusion and 2 hours of reperfusion with haemodynamic and ECG monitoring.</AbstractText>Haemodynamics were not significantly different among the four groups. Losartan increased the threshold for ventricular fibrillation (p=0.0001) and reduced spontaneous ventricular arrhythmias (p=0.002) during ischaemia-reperfusion, while SHS did not (p=0.713, 0.110), and there was no interaction between losartan and SHS. The maximal endothelium-dependent vasorelaxation induced by a calcium ionophore (A23187) was increased by losartan (p=0.007). Myocardial infarct size was smaller in the losartan groups (p=0.032), larger in the SHS groups (p=0.0001), and there was no significant interaction.</AbstractText>In conclusion, losartan decreased infarct size and increased endothelium-dependent vasorelaxation. SHS exposure impaired endothelial function and increased infarct size. The effects of losartan and SHS were consistently independent of each other. These results suggest that the RAS does not contribute to the adverse effects of SHS.</AbstractText> |
3,267 | Biventricular pacing in patients with ICD: how many patients are possible candidates? | About 80 % of patients receiving an implantable cardioverter-defibrillator (ICD) due to life-threatening episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) have structural heart disease. ICD implantation reduces the risk of sudden cardiac death to less than 2 %. However, the major obstacle in these patients is chronic heart failure (CHF). Biventricular stimulation (BIV) has shown its efficiency as an alternative therapy in drug refractory CHF.</AbstractText>According to the InSync registry, we predefined possible indications for BIV as follows: complete branch bundle block (> 120 ms), left-ventricular ejection fraction (EF) < 35 % and NYHA class > II. We evaluated the number of patients presenting this indication at time of implant and during follow-up (FU) at our ICD clinic.</AbstractText>Between 1992 and 1998, 360 patients were provided with an ICD (mean age 64.6 +/- 5.4 yrs, mean EF 37 +/- 14 % at implant, 82 % of patients with organic heart disease). Mean FU was 34 +/- 21 months. During FU 46 patients (13 %) died, 15 of these (33 %) presenting criteria for BIV. 33 patients died of heart failure, there was 1 sudden death and 12 patients died for non-cardiac reasons. 35 % of the patients who died of heart failure had an indication for BIV.</AbstractText>About 10 % of ICD patients had an indication for BIV at time of implant. Over a mean FU period of 34 months, 16% of all patients presented an indication for BIV. Patients with an indication for BIV had a higher mortality rate and more frequent atrial fibrillation compared to patients without. With this data and the good clinical results after BIV-ICD implantation, we consider the implantation of a BIV-ICD system in every patient with appropriate indications.</AbstractText> |
3,268 | Usefulness of reperfusion ventricular arrhythmias in non-invasive prediction of early reperfusion and sustained coronary artery patency in acute myocardial infarction. | Established tenets of occurrence of reperfusion ventricular arrhythmias in acute myocardial infarction (AMI) do not provide insight into the timing of achieving reperfusion or whether coronary artery patency is sustained. We assessed the significance of ventricular arrhythmias in the non-invasive prediction of timely reperfusion and sustained restoration of coronary patency after thrombolysis in patients with AMI.</AbstractText>24-hour Holter monitors were placed in 163 patients with an AMI before administration of thrombolytic therapy. Patients were classified into 3 groups of early (within 2 hours) or late reperfusion, or no-reperfusion, according with clinical and continuous ST-segment electrocardiographic criteria. Ventricular fibrillation, ventricular tachycardia (VT) and accelerated idioventricular rhythm (AIVR) were also categorized as having occurred early (within the first 2 hours) or late (after the first 2-hour period). Angiographic confirmation of coronary patency was determined 2 to 6 days after AMI.</AbstractText>Early reperfusion was predicted by early sustained AIVR in 86% of patients and early non-sustained AIVR in 62.5% of patients, with sensitivity 38% and 77%, and specificity 96% and 69%, respectively; p<0.0001. Late non-sustained AIVR was commonly seen in early and late reperfused patients (92-97%) as well as in non-reperfused patients (74%). Sustained coronary patency was predicted by early sustained AIVR in 93% of patients, as well as by early non-sustained AIVR in 86% of patients and late non-sustained AIVR in 79% of patients, with sensitivity 22%, 55% and 94%, and specificity 95%, 71% and 18%, respectively; p<0.05.</AbstractText>Only the occurrence of sustained AIVR, and probably early non-sustained AIVR convey useful information about both early reperfusion and sustained coronary artery patency. The absence of AIVR does not preclude successful thrombolysis.</AbstractText> |
3,269 | Efficacy and temporal stability of reduced safety margins for ventricular defibrillation: primary results from the Low Energy Safety Study (LESS). | Traditionally, a safety margin of at least 10 J between the maximum output of the pulse generator and the energy needed for ventricular defibrillation has been used because lower safety margins were associated with unacceptably high rates of failed defibrillation and sudden cardiac death. The Low Energy Safety Study (LESS) was a prospective, randomized assessment of the safety margin requirements for modern implantable cardioverter-defibrillator (ICD) systems.</AbstractText>A total of 636 patients undergoing initial ICD implantation with a dual-coil lead and active pulse generator were evaluated. The defibrillation threshold (DFT) and enhanced DFT (DFT+ and DFT++) were measured using a modified step-down protocol. Conversion testing of induced ventricular fibrillation before discharge, at 3 months, and at 12 months was performed, as was randomization to chronic programming at either 2 steps above DFT++ or maximal output. The induced ventricular fibrillation data had conversion success rates of 91.4%, 97.9%, 99.1%, 99.6%, and 99.8% for safety margins of 0, 1, 2, 3, and 4 steps above the DFT++, respectively. A margin of 4 to 6 J was adequate to maintain high conversion success over time (98.9% before discharge versus 99.2% at 12 months; P=NS). Over a mean follow-up of 24+/-13 months, conversion of spontaneously occurring ventricular tachyarrhythmias >200 bpm was identical (97.3%), despite a safety margin difference of 5.2+/-1.1 J for the 2-step group versus 20.8+/-4.2 J for maximal output.</AbstractText>With a rigorous implantation algorithm, a safety margin of about 5 J is adequate for safe implantation of modern ICD systems.</AbstractText> |
3,270 | [Cardiac arrhythmia in cardiac embolism]. | To study cardiac arrhythmia in patients with cardiocerebral embolism, we examined 330 patients with ischemic stroke using ECG and Holter monitoring. 33 patients were control. Group 1 consisted of 104(31.5%) patients with cardioembolic stroke, group 2--of 226(68.5%) patients with other pathogenetic stroke subtypes. Number of patients with rare and frequent supra- and ventricular extrasystole in groups 1 and 2 was not essentially different. Paroxysms of supra- and ventricular tachycardia, variants of sick sinus syndrome (SSS) and transitory atrioventricular block (AV block) of the second and third degree were identified with comparable frequency in groups 1 and 2 (0.9 to 5.8% patients). Paroxysmal atrial fibrillation (AF) was registered in 31.8% of group 1 patients and 15.9% of group 2 patients. Permanent AF occurred in 31.8 and 7.5% patients of groups 1 and 2, respectively (p < 0.00001). Thus, cardiocerebral embolism is observed most frequently in paroxysmal and permanent forms of AF. Variants of extrasystole, paroxysmal supra- and ventricular tachycardia, SSS and AV-block are not associated with embolic complications. |
3,271 | Effect of acute atrial fibrillation on phasic coronary blood flow pattern and flow reserve in humans. | To assess the effect of experimentally induced atrial fibrillation on coronary flow in humans.</AbstractText>In 16 patients (10 men, mean age 43+/-13 years) with normal coronary vessels, baseline and hyperaemic blood pressure and Doppler phasic coronary flow velocity were measured, using a 0.014 inch intracoronary Doppler flow wire, during sinus rhythm, experimentally induced atrial fibrillation, and right atrial pacing at a similar heart rate to that during atrial fibrillation. Coronary flow velocity integral per minute increased significantly during both right atrial pacing and atrial fibrillation compared to sinus rhythm, but during right atrial pacing the increase was greater (85+/-43% vs 52+/-25%, P<0.001). This difference persisted even after correction for the product of heart rate and blood pressure (1.15+/-0.51 vs 0.97+/-0.46, respectively, P<0.02). In a further 12 paced patients (seven men, mean age 54+/-10 years) with complete atrioventricular block the induction of atrial fibrillation (atrial fibrillation with regular RR interval) caused no significant changes in coronary flow velocity variables.</AbstractText>Acute atrial fibrillation in humans causes an increase in coronary flow that is, however, insufficient to compensate for the augmented myocardial oxygen demand, mainly because of the irregularity in the ventricular rhythm that exists during atrial fibrillation.</AbstractText>Copyright 2002 The European Society of Cardiology.</CopyrightInformation> |
3,272 | [Biventricular pacing using two pacemakers and triggered VVT mode in patients with atrial fibrillation and congestive heart failure: a case report]. | A 76-year-old female had undergone implantation of a single chamber pacemaker for sick sinus syndrome 20 years previously. She developed chronic atrial fibrillation and required repeated admission due to congestive heart failure. She had significant mitral and tricuspid regurgitation. Paradoxical movement of the intraventricular septum was severe. Due to right ventricular apical pacing, significant interventricular conduction delay was present with a paced QRS duration of 189 msec. The left ventricular pacing lead was positioned via the coronary sinus. The mode of the previously implanted pacemaker was set at VVT. Biventricular pacing could be achieved even in intrinsic beats by VVT mode. The battery life time was improved. This method is useful in patients with conventional pacemakers. |
3,273 | Grape seed proanthocyanidins improved cardiac recovery during reperfusion after ischemia in isolated rat hearts. | Increasing evidence shows that red wine consumption has cardioprotective effects. These effects have been attributed to the polyphenolic compounds in grapes.</AbstractText>We studied the effects of red grape seed proanthocyanidins on the recovery of postischemic function in isolated rat hearts.</AbstractText>Two groups of rats were fed different doses of proanthocyanidin-rich extract for 3 wk and another group was untreated and served as controls. The animals were then anesthetized and the hearts were isolated and subjected to 30 min of ischemia followed by 2 h of reperfusion. Coronary effluents were collected during the third minute of reperfusion for measurement of oxygen free radicals by using electron spin resonance spectroscopy.</AbstractText>In rats treated with 50 and 100 mg grape seed proanthocyanidins/kg, the incidence of reperfusion-induced ventricular fibrillation was reduced from its control value of 92% to 42% and 25%, respectively (P < 0.05 for both). The incidence of ventricular tachycardia showed the same pattern. In rats treated with 100 mg proanthocyanidins/kg, the recovery of coronary flow, aortic flow, and developed pressure after 60 min of reperfusion was improved by 32% +/- 8%, 98% +/- 8%, and 37% +/- 3%, respectively (P < 0.05 for all) compared with untreated control rats. Electron spin resonance studies indicated that proanthocyanidins significantly inhibited the formation of oxygen free radicals. In rats treated with 100 mg proanthocyanidins/kg, free radical intensity was reduced by 75% +/- 7% (P < 0.05) compared with the control rats.</AbstractText>Grape seed proanthocyanidins have cardioprotective effects against reperfusion-induced injury via their ability to reduce or remove, directly or indirectly, free radicals in myocardium that is reperfused after ischemia.</AbstractText> |
3,274 | [Genetics and arrhythmias]. | In the last 50 years we have been very successful at prolonging survival and improving the quality of life of patients with cardiac disease. The innovations in technology and pharmacology, better preventive and diagnostic tools have provided tremendous breakthroughs. However, despite our best efforts, the majority of cardiac diseases are structural in origin and will progress to their ultimate outcome. Curative therapies are not available due in part to our poor understanding of the basic mechanisms responsible for these diseases. The new developments in molecular genetics and biology are likely to change the way we approach a cardiac patient in the future. The diseases are presently being deciphered at the most basic level, and the information obtained opens new possibilities not only for better therapeutic and diagnostic measures but also for prevention of the disease. |
3,275 | Atrial fibrillation. | The prevalence and incidence of atrial fibrillation increase with age. Atrial fibrillation is associated with a higher incidence of coronary events, stroke, and mortality than sinus rhythm. A fast ventricular rate associated with atrial fibrillation may cause tachycardia-related cardiomyopathy. Management of atrial fibrillation includes treatment of underlying causes and precipitating factors. Immediate direct-current cardioversion should be performed in persons with atrial fibrillation associated with acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta-blockers, verapamil, or diltiazem may be used to immediately slow a fast ventricular rate associated with atrial fibrillation. An oral beta-blocker, verapamil, or diltiazem should be given to persons with atrial fibrillation if a rapid ventricular rate occurs a rest or during exercise despite digoxin. Amiodarone may be used in selected persons with symptomatic life-threatening atrial fibrillation refractory to other drug therapy. Nondrug therapies should be performed in persons with symptomatic atrial fibrillation in whom a rapid ventricular rate cannot be slowed by drug therapy. Paroxysmal atrial fibrillation associated with the tachycardia-bradycardia syndrome should be managed with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in persons with atrial fibrillation in whom symptoms such as dizziness or syncope associated with non-drug-induced ventricular pauses longer than 3 seconds develop. Elective direct-current cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than medical cardioversion in converting atrial fibrillation to sinus rhythm. Unless transesophageal echocardiography shows no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective direct-current or drug cardioversion of atrial fibrillation and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer the treatment strategy of ventricular rate control plus warfarin rather than to maintain sinus rhythm with antiarrhythmic drugs, especially in older patients. Digoxin should not be used in persons with paroxysmal atrial fibrillation. Patients with chronic or paroxysmal atrial fibrillation who are at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio (INR) of 2.0 to 3.0. Persons with atrial fibrillation who are at low risk for stroke or who have contraindications to warfarin should receive 325 mg aspirin daily. |
3,276 | Slowed conduction and ventricular tachycardia after targeted disruption of the cardiac sodium channel gene Scn5a. | Voltage-gated sodium channels drive the initial depolarization phase of the cardiac action potential and therefore critically determine conduction of excitation through the heart. In patients, deletions or loss-of-function mutations of the cardiac sodium channel gene, SCN5A, have been associated with a wide range of arrhythmias including bradycardia (heart rate slowing), atrioventricular conduction delay, and ventricular fibrillation. The pathophysiological basis of these clinical conditions is unresolved. Here we show that disruption of the mouse cardiac sodium channel gene, Scn5a, causes intrauterine lethality in homozygotes with severe defects in ventricular morphogenesis whereas heterozygotes show normal survival. Whole-cell patch clamp analyses of isolated ventricular myocytes from adult Scn5a(+/-) mice demonstrate a approximately 50% reduction in sodium conductance. Scn5a(+/-) hearts have several defects including impaired atrioventricular conduction, delayed intramyocardial conduction, increased ventricular refractoriness, and ventricular tachycardia with characteristics of reentrant excitation. These findings reconcile reduced activity of the cardiac sodium channel leading to slowed conduction with several apparently diverse clinical phenotypes, providing a model for the detailed analysis of the pathophysiology of arrhythmias. |
3,277 | Cocaine/heroin induced rhabdomyolysis and ventricular fibrillation. | A case of cardiorespiratory arrest in a 28 year old man after cocaine and heroin ingestion is described. The arrest is attributed primarily to hyperkalaemia/rhabdomyolysis-a recognised consequence of each of these drugs. The administration of naloxone may have been contributory. He developed acute renal failure, disseminated intravascular coagulopathy with consequent lower limb compartment syndrome requiring fasciotomy. Ventricular fibrillation was identified at thoracotomy. |
3,278 | [Analysis of ECG in ventricular fibrillation in man and animals based on chaos theory]. | The methods of the chaos theory were used to estimate the degree of irregularity of ventricular fibrillation in human and experimental animals. To verify the hypothesis that the degree of chaos depends on the species of the living organisms, the parameters characterizing the degrees of irregularity of ventricular fibrillation were estimated and compared. The comparative analysis was performed using 32 fragments of electrocardiographic records from five patients with sudden ventricular fibrillation bouts and 215 episodes of induced fibrillation in 17 animals. It was shown that fibrillation in human and animals has a different degree of regularity and different values of the chaotic component. The highest values of chaos were recorded in dogs, the lowest degree of chaos was observed in human. Rabbits and rats are intermediate, between dogs and humans. The fractuality of the structure-function organization of myocardium is discussed. |
3,279 | Ventricular fibrillation caused by electrocoagulation during laparoscopic surgery. | A 35-year-old man with morbid obesity was admitted to our hospital to undergo gastric banding gastroplasty by the laparoscopic approach. Aside from his morbid adiposity, with a body mass index (BMI) of 49.9 kg/m2, the patient was healthy. During the procedure, he developed ventricular fibrillation (VF) while a diathermic knife was being used. After defibrillation, his heart rate returned to normal. The postoperative clinical course was uneventful, and there was no evidence of permanent heart failure. Although the VF could have been caused by patient- or material-related variables, it was most likely the result of unwanted electrical effects. Specifically, the occurrence of an arc between the patient's tissue and the tip of the electrode during cutting in the coagulation mode can lead to low-frequency current. The modified low-frequency current may produce arrhythmias. Thus, the use of the coagulation mode to cut tissue in the cardiac region during laparoscopic procedures could increase the risk for arrhythmias. An understanding of the physical principles of electrosurgery, as well as familiarity with the equipment and its various functions, is essential for the patient's safety. In addition, cardioversion equipment should be readily available on every surgical unit. |
3,280 | Electrocardiographic alterations in patients hospitalized with leptospirosis in the Brazilian city of Salvador. | To report the frequency and types of electrocardiographic alterations in patients with leptospirosis in the first 24 hours of hospitalization.</AbstractText>We analyzed the electrocardiograms of 157 patients admitted to the Hospital Couto Maia in the city of Salvador, in the State of Bahia, Brazil, from March 1998 to June 1999. The electrocardiograms were performed in the first 24 hours after hospital admission, independent of the clinical manifestations of the patients.</AbstractText>The mean +/- SD for patients' age was 35.5+/- 13.7 (median = 32) years, and jaundice was present in 95.5% of them. Alterations in the electrocardiogram were detected in 68.2% (107/157) of the patients (95% confidence interval = 60.6% - 75.1%). Atrial fibrillation was the most frequent arrhythmia, occurring in 10.8% (17/157) of the patients. Other frequent findings were alterations in ventricular repolarization detected in 38.9% (61/157) of patients and first-degree atrioventricular block in 10.2% (16/157). The patients with atrial fibrillation were older and had higher levels of creatinine and aminotransferases.</AbstractText>In this sample, approximately 2/3 of the patients had electrocardiographic alterations after hospital admission. Of the major arrhythmias, atrial fibrillation was the most frequent, and the patients with this arrhythmia had evidence of more severe disease. The relation between the presence and type of electrocardiographic alteration and the prognosis of leptospirosis is yet to be assessed.</AbstractText> |
3,281 | [Evaluation of infrequent episodes of palpitations with a patient-activated hand-held electrocardiograph]. | The disadvantage of most devices presently available for cardiac rhythm event monitoring is that they require either permanently attached electrodes or the subcutaneous implantation of the device. The aim of the study was to evaluate the feasibility and diagnostic yield of a hand-held, portable electrocardiograph for the evaluation of infrequent episodes of palpitations. In contrast to other devices, this electrocardiograph records and stores the electrocardiograms with integral electrodes, which makes long-term attached electrodes not unnecessary.</AbstractText>The study included 55 consecutive patients with palpitations less than once a week. The patients received the electrocardiograph Miniscope MS-3 with integral tripod electrodes (Schiller AG, Switzerland) to record a one-channel electrocardiogram during a recurrent episode. The frequency of device activation and the atrial rhythm during an episode was assessed.</AbstractText>Forty-one (75%) patients had at least one episode within 38 +/- 22 days. The first episode occurred within the first week in 18 cases, during the 2nd in 9, during the 3rd in 9, during the 4th in 2 patients, and in 3 patients between the 4th and 12th week. All episodes could be properly analyzed: Twenty-three patients had sinus rhythm, 7 paroxysmal atrial fibrillation, 7 paroxysmal atrial flutter, and 4 an AV node reentry tachycardia. Eleven of the 23 patients with sinus rhythm additionally had premature atrial or ventricular contractions. Mean heart rate was 111 +/- 45 bpm. A second episode was recorded in 22 and a third episode in 12 patients. All patients had during the subsequent episode the same cardiac rhythm as during their first episode.</AbstractText>Patients evaluated for their infrequent palpitations had during event monitoring a recurrent episode in 75% that occurred in 88% within the first 4 weeks. All patients were able to activate the electrocardiograph and could store an electrocardiogram with the integral electrodes. Patient-activated event monitoring reliably identified patients with an atrial arrhythmia who need further invasive evaluation and treatment, and ruled out patients with sinus rhythm and premature contractions.</AbstractText> |
3,282 | A stochastic nonlinear autoregressive algorithm reflects nonlinear dynamics of heart-rate fluctuations. | Current methods for detecting nonlinear determinism in a time series require long and stationary data records, as most of them assume that the observed dynamics arise only from the internal, deterministic workings of the system, and the stochastic portion of the signal (the noise component) is assumed to be negligible. To explicitly account for the stochastic portion of the data we recently developed a method based on a stochastic nonlinear autoregressive (SNAR) algorithm. The method iteratively estimates nonlinear autoregressive models for both the deterministic and stochastic portions of the signal. Subsequently, the Lyapunov exponents (LE) are calculated for the estimated models in order to examine if nonlinear determinism is present in the deterministic portion of the fitted model. To determine if nonlinear dynamic analysis of heart-rate fluctuations can be used to assess arrhythmia susceptibility by predicting the outcome of invasive cardiac electrophysiologic study (EPS), we applied the SNAR algorithm to noninvasively measured resting sinus-rhythm heart-rate signals obtained from 16 patients. Our analysis revealed that a positive LE was highly correlated to a patient with a positive outcome of EPS. We found that the statistical accuracy of the SNAR algorithm in predicting the outcome of EPS was 88% (sensitivity=100%, specificity=75%, positive predictive value=80%, negative predictive value=100%, p=0.0019). Our results suggest that the SNAR algorithm may serve as a noninvasive probe for screening high-risk populations for malignant cardiac arrhythmias. |
3,283 | Intelligent multichannel stimulator for the study of cardiac arrhythmias. | An intelligent multichannel stimulator (IMS) has been designed and built for use in a cardiac research environment. The device is capable of measuring and responding to cardiac electrophysiological phenomena in real time with carefully timed and placed electrical stimuli. The system consists of 16 channels of sense/stimulation electronics controlled by a digital signal processor (DSP) data acquisition card and a host computer and can be expanded to include more channels. The DSP allows for powerful and flexible algorithms to be implemented for real-time interaction with the cardiac tissue. Although a number of possible uses can be conceived for such a device, the initial motivation was to improve upon attempts to terminate fibrillation by pacing. The IMS was tested in an open-chest animal model, both in sinus rhythm and during fibrillation. It was shown to be an effective research tool by demonstrating the ability to measure and respond to cardiac activations in real time using complex numerical algorithms and appropriately timed stimuli. |
3,284 | Enhancement of glutathione cardioprotection by ascorbic acid in myocardial reperfusion injury. | The present experiment determined the effects of glutathione and ascorbic acid, the two most important hydrophilic antioxidants, on myocardial ischemia-reperfusion injury and evaluated their relative therapeutic values. Isolated rat hearts were subjected to ischemia (30 min) and reperfusion (120 min) and treated with ascorbic acid, glutathione monoethyl ester (GSHme), or their combination at the onset of reperfusion. Administration of 1 mM GSHme alone, but not 1 mM ascorbic acid alone, significantly attenuated postischemic injury (P < 0.05 versus vehicle). Most interestingly, coadministration of ascorbic acid with GSHme markedly enhanced the protective effects of GSHme (P < 0.01 versus vehicle). The protection exerted by the combination of GSHme and ascorbic acid at 1 mM each was significantly greater than that observed with 1 mM GSHme alone (P < 0.05). Moreover, treatment with GSHme alone or GSHme plus ascorbic acid markedly reduced myocardial nitrotyrosine levels, suggesting that these treatments attenuated myocardial peroxynitrite formation. These results demonstrated that 1) GSHme, but not ascorbic acid, exerted protective effects against ischemia-reperfusion injury; and 2) the protective effects of GSHme were further enhanced by coadministration with ascorbic acid, suggesting a synergistic effect between GSHme and ascorbic acid. |
3,285 | Genetic analysis of Brugada syndrome in Israel: two novel mutations and possible genetic heterogeneity. | Idiopathic ventricular fibrillation in patients with an electrocardiogram (ECG) pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 (now frequently called Brugada syndrome) is associated with a high incidence of syncopal episodes or sudden death. The disease is inherited as an autosomal dominant trait. Mutations in SCN5A, a cardiac sodium channel gene, have been recently associated with Brugada syndrome. We have analyzed 7 patients from Israel affected with Brugada syndrome. The families of these patients are characterized by a small number of symptomatic members. Sequencing analysis of SCN5A revealed two novel mutations, G35S and R104Q, in two Brugada patients, and a possible R34C polymorphism in two unrelated controls. No mutations were detected in 5 other patients, suggesting genetic heterogeneity. Low penetrance is probably the cause for the small number of symptomatic members in the two families positive for the SCN5A mutations. |
3,286 | NCX4016 (NO-aspirin) reduces infarct size and suppresses arrhythmias following myocardial ischaemia/reperfusion in pigs. | 1. The effect of the nitro-derivative of aspirin, NCX4016, was assessed on ischaemic ventricular arrhythmias and myocardial infarct size in anaesthetized pigs in comparison to native aspirin. 2. Pigs were given aspirin (10 mg kg(-1); n=6), low dose NCX4016 (18.4 mg kg(-1); n=6) or high dose NCX4016 (60 mg kg(-1); n=7) orally for 5 days prior to coronary occlusion and reperfusion. None of the interventions had any effect on baseline haemodynamics prior to coronary occlusion in comparison to control pigs (n=9). Aspirin and high dose NCX4016 both prevented the generation of thromboxane A(2) from platelets activated ex vivo with A23187 (30 microM), whereas all three interventions markedly attenuated platelet aggregation in response to collagen in whole blood in comparison to controls. 3. None of the drug interventions had any effect on the incidence of ventricular fibrillation (VF) during myocardial ischaemia (100% in all groups). However, 60 mg kg(-1) NCX4016 significantly attenuated the total number of premature ventricular beats (PVB's) (62+/-16 vs 273+/-40 in control pigs; P<0.05) during the first 30 min of occlusion. The higher dose of NCX4016 also significantly reduced myocardial infarct size (22.6+/-3.7% of area at risk vs 53.0+/-2.8% of area at risk in control pigs; P<0.05). 4. These results suggest that the nitro-derivative of aspirin, NCX4016, is an effective antiplatelet agent, which unlike aspirin also reduces the extent of myocardial injury following ischaemia and reperfusion. |
3,287 | Action potential duration restitution and ventricular fibrillation due to rapid focal excitation. | The focal source hypothesis of ventricular fibrillation (VF) posits that rapid activation from a focal source, rather than action potential duration (APD) restitution properties, is responsible for the maintenance of VF. We injected aconitine (100 microg) into normal isolated perfused swine right ventricles (RVs) stained with 4-[beta-[2-(di-n-butylamino)-6-naphthyl]vinyl]pyridinium (di-4-ANEPPS) for optical mapping studies. Within 97 +/- 163 s, aconitine induced ventricular tachycardia (VT) with a mean cycle length 268 +/- 37 ms, which accelerated before converting to VF. Drugs that flatten the APD restitution slope, including diacetyl monoxime (10-20 mM, n = 6), bretylium (10-20 microg/ml, n = 3), and verapamil (2-4 microg/ml, n = 3), reversibly converted VF to VT in all cases. In two RVs, VF persisted despite of the excision of the aconitine site. Simulations in two-dimensional cardiac tissue showed that once VF was initiated, it remained sustained even after the "aconitine" site was eliminated. In this model of focal source VF, the VT-to-VF transition occurred due to a wave break outside the aconitine site, and drugs that flattened the APD restitution slope converted VF to VT despite continuous activation from aconitine site. |
3,288 | Sildenafil-nitric oxide donor combination promotes ventricular tachyarrhythmias in the swine right ventricle. | We tested the hypothesis that sildenafil, singly or in combination with nitric oxide (NO) donors, promotes ventricular tachycardia (VT) and ventricular fibrillation (VF). Vulnerability to VT/VF was tested by rapid pacing in eight isolated normal swine right ventricles (RV). The endocardial activation was optically mapped, and the dynamic action potential duration (APD) restitution curves were constructed with metal microelectrodes. At baseline, no VT/VF could be induced. Sildenafil (0.2 microg/ml) or NO donor singly or in combination did not alter VT/VF vulnerability. However, when 2 microg/ml sildenafil was combined with NO donors, the incidence of VT and VF rose significantly (P < 0.01). VT with a single periodic wavefront was induced in five of eight RVs, and VF with multiple wavefronts was induced in all eight RVs. The sildenafil-NO donor pro-VT/VF combination significantly increased the maximum slope of the APD restitution curve and the amplitude of the APD alternans. The pro-VT/VF effects of sildenafil were reversible after drug-free Tyrode solution perfusion. We conclude that a sildenafil (2 microg/ml) and NO donor combination increases VT/VF vulnerability in the normal RV by a mechanism compatible with the restitution hypothesis. |
3,289 | Angiotensin II subtype 1 (AT1) receptors contribute to ischemic contracture and regulate chemomechanical energy transduction in isolated transgenic rat (alphaMHC-hAT1)594-17 hearts. | The role of AT1 receptors in myocardial ischemia/reperfusion injury is unclear. We, therefore, investigated the effects of the AT1 receptor antagonist irbesartan (Irb) in isolated hearts of selective myocardial AT1 overexpressing transgenic [transgenic(alphaMHC-hAT1)594-17] and Sprague-Dawley rats (SD) subjected to ischemia/reperfusion injury.</AbstractText>Hearts of 4-week-old male SD or transgenic rats were isolated and perfused with Krebs-Henseleit buffer with or without 10 microM Irb in Langendorff mode. After 15 min of stabilization, pressure-volume curves were obtained and the hearts subjected to 20 min ischemia followed by 30 min reperfusion. A second set of pressure-volume curves was obtained thereafter. Left ventricular developed pressure (LVDP), end-diastolic pressure (LVEDP), total coronary flow (CF) and oxygen consumption (MVO2) were recorded continuously. Myocardial efficiency was derived from the slope of relations of MVO2 to pressure/volume area. After 20 min ischemia, LVEDP was significantly higher in transgenic than in SD (35.7+/-1.8 vs. 29.2+/-1.0 mmHg, P<0.05) or Irb treated transgenic hearts (24.3+/-1.6 mmHg, P<0.05). Myocardial efficiency was increased by Irb before ischemia. Ischemia increased efficiency in SD but not in transgenic rats, Irb increased efficiency in transgenic hearts post-ischemia.</AbstractText>Transgenic hearts developed ischemic contracture more rapidly than SD hearts as indicated by higher LVEDP during ischemia. This response was antagonized by Irb, indicating a role of AT1 receptors in ischemic contracture, AT1-receptors also appear to be involved in the control of myocardial efficiency.</AbstractText> |
3,290 | Sudden death in patients with implantable cardioverter defibrillators: the importance of post-shock electromechanical dissociation. | The purpose of this study was to determine the mechanisms of sudden death (SD) in patients with ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) treated with an implantable cardioverter defibrillator (ICD).</AbstractText>Despite ICD therapy, some patients with VT/VF still die suddenly. Optimal ICD use requires determination of the mechanisms of these residual SDs.</AbstractText>We reviewed 320 patient deaths during trials of Medtronic transvenous ICD systems (Medtronic Inc., Minneapolis, Minnesota). Sudden deaths were further categorized according to mechanism. Post-shock electromechanical dissociation (EMD) describes a scenario where VT/VF was appropriately detected and treated by an ICD shock that restored a physiologic rhythm, but death still occurred immediately by EMD.</AbstractText>A mode of death could be ascribed for 317 patients-90 (28%) were sudden, 156 (49%) were non-sudden cardiac, and 71 (22%) were noncardiac. A mechanism of SD was proposed for 68 patients-20 (29%) had post-shock EMD, 17 (25%) had VT/VF uncorrected by shocks, 11 (16%) had primary electromechanical dissociation, 9 (13%) had incessant VT/VF, 5 (7%) had VT/VF after their ICD was deactivated or removed, and 6 (9%) had single instances of various other terminal events. Only New York Heart Association functional class independently predicted SD by post-shock EMD.</AbstractText>The most common mechanism of SD in patients with an ICD is VT/VF treated with an appropriate shock followed by EMD. As this mechanism accounted for 29% of the SDs to which a cause could be ascribed, this mechanism of SD warrants further investigation.</AbstractText> |
3,291 | Cardiac resynchronization in patients with congestive heart failure and chronic atrial fibrillation: effect of upgrading to biventricular pacing after chronic right ventricular pacing. | This study assessed the effects of biventricular pacing (BVP) on ventricular function, functional status, quality of life and hospitalization in patients with congestive heart failure (CHF), prior atrioventricular (AV) junction ablation and right ventricular (RV) pacing performed for chronic atrial fibrillation (AF).</AbstractText>Although the benefit of BVP in CHF should theoretically extend to the patient with chronic RV pacing and AF, to our knowledge, no study has determined the effects of BVP on symptoms and ventricular function in these patients. This patient population allows for the evaluation of ventricular resynchronization independent of any BVP-induced changes on the AV interval.</AbstractText>Twenty consecutive patients with severe CHF (ejection fraction < or = 0.35, New York Heart Association [NYHA] functional class III or IV), prior AV junction ablation and RV pacing performed for permanent AF of at least six months' duration were studied. Electrocardiograms, echocardiograms, functional status evaluations and quality of life surveys were completed before and at three to six months after implant.</AbstractText>The NYHA functional classification improved 29% (p < 0.001). The left ventricular (LV) ejection fraction increased 44% (p < 0.001), the LV diastolic diameter decreased 6.5% (p <0.003) and the end-systolic diameter decreased 8.5% (p < 0.01). The number of hospitalizations decreased by 81% (p < 0.001). The scores on the Minnesota Living with Heart Failure survey improved by 33% (p < 0.01).</AbstractText>We conclude that BVP improves the LV function and the symptoms of CHF in patients with permanent AF and chronic RV pacing. These benefits are comparable to those described for patients in sinus rhythm suggesting that BVP acts through ventricular resynchronization rather than optimization of the AV delay.</AbstractText> |
3,292 | Cardioprotective effect of mexiletine in acute myocardial ischemia tudies in the rabbit closed chest ischemia mode. | ATP-sensitive K+ (KATP) channel openers have a cardioprotective effect and so mexiletine (Mex), a class Ib anti-arrhythmic drug, may also be cardioprotective because of its KATP channel-opening effect. The present study examined the effect of Mex on acute myocardial ischemia in a closed-chest acute ischemia and reperfusion model in rabbits. The rabbits were divided into 3 groups: (1) control (n=8); (2) Mex (n=8), continuous infusion of mexiletine (24 mg x kg(-1) h(-1)); and (3) Mex+Gli (n=8), pre-administration of glibenclamide (Gli; 0.5mg/kg) followed by mexiletine infusion. The incidence of arrhythmia, the hemodynamics and left ventricular ejection fraction (LVEF), and the infarct size were evaluated and compared among the 3 groups. The incidence of fatal ventricular fibrillation (VF) was least in the Mex group. The LVEF at 30 min after reperfusion was least in the Mex group, but at 360 min after reperfusion, it was least in the Mex+Gli group. The area of myocardial infarction determined by 2,3-triphenyltetrazolium chloride (TTC) staining was smallest in the Mex group. In this model, Mex reduced infarct size and improved left ventricular function during the late phase after reperfusion, although the effect was totally negated by the addition of glibenclamide. |
3,293 | Expanding automatic external defibrillators to include automated detection of cardiac, respiratory, and cardiorespiratory arrest. | The new Guidelines of the American Heart Association state that lay rescuers can no longer rely on the manual pulse check to confirm cardiac arrest in an unresponsive patient. We were therefore prompted to develop a method for automated determination of the presence or absence of cardiac contraction and breathing. The technique was designed to be incorporated into conventional automated external defibrillators and to work in conjunction with the information derived from rhythm analyses by the automated defibrillator. Using conventional electrocardiographic sensing and defibrillation electrodes, the transthoracic impedance was measured by passing a constant amplitude alternating current of 5 mA through the thorax at a frequency of 35 kHz. In five anesthetized male domestic swine, we observed pulses that were coincident with cardiac contraction documented by esophageal echocardiography. In addition, we observed larger signals of lower frequency that were time related to ventilation and documented by capnography. Both signals disappeared after inducing ventricular fibrillation. The impedance measurement identified respiratory arrest in anesthetized animals and primary cardiac arrest after ventricular fibrillation was induced. The cardiac arrest detector is therefore likely to augment the current information provided by automated defibrillators and to allow for more precise verbal prompting of lay rescuers. |
3,294 | Arginine vasopressin during cardiopulmonary resuscitation: laboratory evidence, clinical experience and recommendations, and a view to the future. | When stimulating adult pigs with ventricular fibrillation or postcountershock pulseless electrical activity for cardiopulmonary resuscitation, vasopressin improved vital organ blood flow, cerebral oxygen delivery, ability to be resuscitated, and neurologic recovery better than epinephrine. In pediatric preparations with asphyxia, epinephrine was superior to vasopressin, whereas in both pediatric pigs with ventricular fibrillation and adult porcine models with asphyxia, combinations of vasopressin and epinephrine proved to be highly effective. This may suggest that a different efficiency of vasopressors in pediatric vs. adult preparations and different effects of dysrhythmic vs. asphyxial cardiac arrest on vasopressor efficiency may be of significant importance. Whether these theories can be extrapolated to humans is unknown at this time. In patients who experienced out-of-hospital ventricular fibrillation, a larger proportion of patients treated with vasopressin survived 24 hrs compared with patients treated with epinephrine; during in-hospital cardiopulmonary resuscitation, comparable short-term survival was found in groups treated with either vasopressin or epinephrine. Currently, a large trial comprising patients who experience out-of-hospital cardiac arrest and who are treated with vasopressin vs. epinephrine is ongoing in Germany, Austria, and Switzerland. The new cardiopulmonary resuscitation guidelines of both the American Heart Association and the European Resuscitation Council consider 40 units of vasopressin intravenously and 1 mg of epinephrine intravenously equally effective for the treatment of adult patients with ventricular fibrillation; however, because of a lack of clinical data, no recommendation for vasopressin has been made for adult patients with asystole and pulseless electrical activity or for pediatric patients. |
3,295 | Pharmacologic defibrillation. | Ventricular fibrillation (VF) is generally sustained. The mechanism is, at least in part, caused by progressive accumulation of intracellular sodium and calcium ions during untreated ventricular fibrillation, which subsequently increases defibrillation threshold. Cariporide, a potent and specific inhibitor of the sodium-hydrogen exchanger, has been shown to reduce intracellular sodium and calcium concentration in the setting of myocardial ischemia and reperfusion. We hypothesized that cariporide would facilitate defibrillation from prolonged ventricular fibrillation in a rodent model of cardiac arrest and resuscitation. Fifteen Sprague-Dawley rats were randomized to receive bolus injections of cariporide or placebo in a dose of 3 mg/kg into the right atrium either 5 mins before or at 8 mins after onset of ventricular fibrillation. Ventricular fibrillation was electrically induced and untreated for 8 mins. Precordial compression together with mechanical ventilation was then started and continued for an interval of 8 mins before attempted electrical defibrillation. All but one placebo-treated animal were successfully resuscitated. Spontaneous defibrillation with restoration of circulation was observed in both cariporide pretreatment and treatment groups but in none of the placebo-treated animals. The duration of postresuscitation survival was significantly increased in animals pretreated with cariporide. Therefore, sodium-hydrogen exchanger inhibitors may provide new options in settings of cardiopulmonary resuscitation to facilitate defibrillation. |
3,296 | Benefits of resveratrol in women's health. | Resveratrol and trans-resveratrol are powerful phytoestrogens, present in the skins of grapes and other plant foods and wine, which demonstrate a broad spectrum of pharmacological and therapeutic health benefits. Phytoestrogens are naturally occurring plant-derived nonsteroidal compounds that are functionally and structurally similar to steroidal estrogens, such as estradiol, produced by the body. Various studies, reviewed herein, have demonstrated the health benefits of phytoestrogens in addressing climacteric syndrome including vasomotor symptoms and postmenopausal health risks, as well as their anticarcinogenic, neuroprotective and cardioprotective activities and prostate health and bone formation promoting properties. Conventional HRT drugs have been demonstrated to cause serious adverse effects including stroke and gallbladder disease, as well as endometrial, uterine and breast cancers. Recent research demonstrates that trans-resveratrol binds to human estrogen receptors and increases estrogenic activity in the body. We investigated the effects of protykin, a standardized extract of trans-resveratrol from Polygonum cuspidatum, on cardioprotective function, the incidence of reperfusion-induced arrhythmias and free radical production in isolated ischemic/reperfused rat hearts. The rats were orally treated with two different daily doses of protykin for 3 weeks. Coronary effluents were measured for oxygen free radical production by electron spin resonance (ESR) spectroscopy in treated and drug-free control groups. In rats treated with 50 and 100 mg/kg of protykin, the incidence of reperfusion-induced ventricular fibrillation was reduced from its control value of 83% to 75% (p < 0.05) and 33% (p < 0.05), respectively. Protykin was seen to possess cardioprotective effects against reperfusion-induced arrhythmias through its ability to reduce or remove the reactive oxygen species in ischemic/reperfused myocardium. Taken together, these data suggest that trans-resveratrol supplementation may be a potential alternative to conventional HRT for cardioprotection and osteoporosis prevention and may confer other potential health benefits in women. |
3,297 | Prognostic value of low-dose dobutamine echocardiography in patients with idiopathic dilated cardiomyopathy. | Dobutamine echocardiography is widely used for the evaluation of myocardial contractile reserve. The purpose of the study was to determine the prognostic value of low-dose dobutamine echocardiography in patients with idiopathic dilated cardiomyopathy (IDCM).</AbstractText>The study group consisted of 77 consecutive patients with recently diagnosed IDCM (mean [+/- SD] age, 49 +/- 9 years; men, 82%) and left ventricular (LV) ejection fractions of < 40%.</AbstractText>Two-dimensional and Doppler echocardiographic variables were measured before and after the infusion of dobutamine at the rate of 10 microg/kg/min for 5 min.</AbstractText>During a mean follow-up period of 63 +/- 7 months (range, 49 to 75 months) 30 patients (39%) died and five patients (6%) underwent successful heart transplantations. Using multivariate regression analysis, the only significant factors related to fatal outcome or the need for cardiac transplantation were the following: (1) LV end-systolic volume of > 150 mL after low-dose dobutamine infusion (odds ratio [OR], 2.2; confidence interval [CI], 1.2 to 4.1; p = 0.011); (2) no decrease of LV end-diastolic volume after dobutamine infusion (OR, 1.9; CI, 1.1 to 3.4; p = 0.031); (3) atrial fibrillation (OR, 2.7; CI, 1.4 to 5.3; p = 0.003); and (4) male gender (OR, 2.6; CI, 1.2 to 5.5; p = 0.017). A scoring system was proposed with one point assigned for each of the above-mentioned factors. The mortality rates for total scores of 0, 1, 2, 3, and 4 were 0%, 19%, 48%, 83%, and 100%, respectively.</AbstractText>The response of the LV to low-dose dobutamine infusion adds clinically valuable prognostic information to the evaluation of the patient with IDCM.</AbstractText> |
3,298 | Amiodarone used in successful resuscitation after near-fatal flecainide overdose. | We report the case of a 45-year-old woman who had ingested 2000 mg of flecainide with suicidal intent. She developed therapy-resistant ventricular fibrillation (VF) with cardiopulmonary arrest. Cardiopulmonary resuscitation and advanced life support were sustained for 64 min. Following intravenous amiodarone, the patient developed an effective spontaneous rhythm and resumed breathing. An amiodarone infusion was started and continued over a period of 72 h. She recovered completely after 5 days, leaving the hospital without neurological sequelae. Serum flecainide levels approximately 5 h post-ingestion were 850 mg/l. This case report confirms the value of amiodarone in drug-resistant VF, even when the cause may be another antiarrhythmic drug such as flecainide. |
3,299 | Predicting the success of defibrillation by electrocardiographic analysis. | We investigated an electrocardiographic signal analysis technique for predicting whether an electrical shock would reverse ventricular fibrillation (VF) in an effort to minimize the damaging effects of repetitive shocks during CPR.</AbstractText>An established model of CPR was utilized. VF was electrically induced in anesthetized 40 kg domestic pigs. Defibrillation was attempted after either 4 or 7 min of untreated VF. Failing to reverse VF, a 1 min interval of precordial compression and mechanical ventilation preceded each subsequent defibrillation attempt. The amplitude frequency spectrum of digitally filtered VF wavelets was computed with Fourier analysis during uninterrupted precordial compression from conventional right infraclavicular and left apical electrodes. Of a total of 34 electrical defibrillation attempts, 24 animals were restored to spontaneous circulation (ROSC). An amplitude spectrum analysis (AMSA) value of 21 mV Hz had a negative predictive value of 0.96 and a positive predictive value of 0.78.</AbstractText>AMSA predicted when an electrical shock failed to restore spontaneous circulation during CPR with a high negative predictive value. This method potentially fulfills the need for minimizing ineffective defibrillation attempts and their attendant adverse effects on the myocardium.</AbstractText> |
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