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6,200 | Endothelin-B receptors and ventricular arrhythmogenesis in the rat model of acute myocardial infarction. | The arrhythmogenic effects of endothelin-1 (ET-1) are mediated via ETA-receptors, but the role of ETB-receptors is unclear. We examined the pathophysiologic role of ETB-receptors on ventricular tachyarrhythmias (VT/VF) during myocardial infarction (MI). MI was induced by coronary ligation in two animal groups, namely in wild-type (n = 63) and in ETB-receptor-deficient (n = 61) rats. Using a telemetry recorder, VT/VF episodes were evaluated during phase I (the 1st hour) and phase II (2-24 h) post-MI, with and without prior beta-blockade. Action potential duration at 90% repolarization (APD90) was measured from monophasic epicardial recordings and indices of sympathetic activation were assessed using fast-Fourier analysis of heart rate variability. Serum epinephrine and norepinephrine were measured with radioimmunoassay. MI size was similar in the two groups. There was a marked temporal variation in VT/VF duration; during phase I, it was higher (p = 0.0087) in ETB-deficient (1,519 +/- 421 s) than in wild-type (190 +/- 34 s) rats, but tended (p = 0.086) to be lower in ETB-deficient (4.2 +/- 2.0 s) than in wild-type (27.7 +/- 8.0 s) rats during phase II. Overall, the severity of VT/VF was greater in ETB-deficient rats, evidenced by higher (p = 0.0058) mortality (72.0% vs. 32.1%). There was a temporal variation in heart rate and in the ratio of low- to high-frequency spectra, being higher (<0.001) during phase I, but lower (p < 0.05) during phase II in ETB-deficient rats. Likewise, 1 h post-MI, serum epinephrine (p = 0.025) and norepinephrine (p < 0.0001) were higher in ETB-deficient (4.20 +/- 0.54, 14.24 +/- 1.39 ng/ml) than in wild-type (2.30 +/- 0.59, 5.26 +/- 0.67 ng/ml) rats, respectively. After beta-blockade, VT/VF episodes and mortality were similar in the two groups. The ETB-receptor decreases sympathetic activation and arrhythmogenesis during the early phase of MI, but these effects diminish during evolving MI. |
6,201 | Ventricular fibrillation during sport activity successfully treated. | Survival after out-of-hospital cardiopulmonary arrest is estimated at less than 5%. We report a case of ventricular fibrillation during sports activity. Cardiopulmonary resuscitation was initiated early by a layperson, and defibrillation was successfully performed within less than three minutes, with an automated external defibrillator. The public access to defibrillation programs has increased the survival after out-of-hospital ventricular fibrillation. We should encourage the training of laypeople in relation to the use of automated external defibrillators and the Basic Life Support program by stimulating their implementation in places where large numbers of people gather or where people are at a high risk of sudden death, as is the case of sports centers. |
6,202 | Ambulatory ECG-based T-wave alternans and heart rate turbulence predict high risk of arrhythmic events in patients with old myocardial infarction. | Few studies have explored risk stratification of arrhythmic events in patients with ischemic heart diseases according to T-wave alternans (TWA) using modified moving average (MMA) method and heart rate turbulence (HRT).</AbstractText>A retrospective analysis of 63 patients who underwent MMA-based TWA and HRT divided the patients into 3 groups: group-C of 21 controls, group-O of 21 patients with old myocardial infarction (OMI) showing no episodes of sustained ventricular tachyarrhythmia (SVT), and group-V of 21 OMI patients with episodes of SVT who received an implantable cardioverter-defibrillator. Among the 3 groups, positive TWA (>or=65 microV) and impaired HRT were observed most frequently in group-V (P<0.05). Using a logistic regression model, TWA yielded an odds ratio of 4.9 (95% confidence interval: 1.2-19.6, P<0.05), which was the only significant covariate for the incidence of life-threatening ventricular arrhythmias during a mean follow-up of 72 months.</AbstractText>Patients with OMI showing episodes of SVT have a high risk for cardiac death because of abnormal repolarization and autonomic regulation. The analysis of MMA-based TWA and HRT can be a useful tool for predicting OMI patients at high risk of arrhythmic events.</AbstractText> |
6,203 | Atrial fibrillation and long-term prognosis in patients hospitalized for heart failure: results from heart failure survey in Israel (HFSIS). | Atrial fibrillation (AF) and heart failure (HF) commonly coexist, and each adversely affects the other. The aim of the study was to prospectively evaluate the impact of AF and its subtypes on management, and early and long-term outcome of hospitalized HF patients.</AbstractText>Data were prospectively collected on HF patients hospitalized in all public hospitals in Israel as part of a national survey (HFSIS). Atrial fibrillation patients were subdivided into intermittent and chronic AF subgroups. During March-April 2003, we enrolled 4102 HF patients, of whom 1360 (33.2%) had AF [600 (44.1%) intermittent, 562 (41.3%) chronic]. Patients with AF were older (76.9 +/- 10.5 vs. 71.7 +/- 12.6 years, P = 0.0001), males, with preserved LV systolic function. Crude mortality rates for AF patients were progressively and consistently higher during hospitalization and during the 4-year follow-up period, especially in the chronic AF group (P = 0.0001). After covariate adjustment, AF was associated with increased 1-year mortality [HR 1.19, 95% CI (1.03-1.36)].</AbstractText>AF was present in a third of hospitalized HF patients, and identified a population with increased mortality risk, largely due to co-morbidities.</AbstractText> |
6,204 | Clinical utility of single-beat E/e' obtained by simultaneous recording of flow and tissue Doppler velocities in atrial fibrillation with preserved systolic function. | We evaluated the usefulness of the ratio of the early diastolic transmitral flow velocity (E) to the mitral annular velocity (e') calculated from simultaneously recorded E and e' in atrial fibrillation (AF).</AbstractText>The ratio of the E to the e' (E/e') has been reported as a useful index even in AF patients. However, E and e' were measured during different beats in the previous studies.</AbstractText>Fifty-six AF patients with preserved systolic function (mean age 66 +/- 11 years) underwent routine echocardiographic study. The E/e' was calculated from the E and e' simultaneously recorded by the dual Doppler echocardiography. A single-beat E/e' was calculated from simultaneously recorded E and e' when the preceding RR interval/pre-preceding RR interval = 1. Brain natriuretic peptide (BNP) levels were also examined. Twenty-one patients underwent simultaneous pulmonary artery catheterization.</AbstractText>The single-beat lateral E/e' correlated with pulmonary capillary wedge pressure (PCWP) (r = 0.74, p < 0.001). The single-beat lateral E/e' of >or=11 could predict elevated PCWP (>or=15 mm Hg) with a sensitivity of 90% and a specificity of 90%. The single-beat lateral E/e' also correlated well with the log BNP concentration. The single-beat lateral E/e' of >or=9.2 predicted a plasma BNP level of >or=200 pg/ml with 88% sensitivity and 84% specificity.</AbstractText>The single-beat lateral E/e' correlated with plasma BNP level and PCWP in AF patients with preserved systolic function. In addition, the single-beat lateral E/e' (>or=11) was a good predictor of elevated PCWP (>or=15 mm Hg). Dual Doppler echocardiography offers an advantage of providing the single-beat lateral E/e' correctly even in AF patients, for the evaluation of left ventricular diastolic function.</AbstractText> |
6,205 | Verapamil-associated cardiogenic shock in a 71-year-old man with myasthenia gravis: a case report. | Myasthenia gravis is a rare neuromuscular disorder associated with a reduction in the availability of acetylcholine receptors at the post-synaptic membranes of skeletal muscles. This is caused by the production of anti-acetylcholine receptor antibodies at the neuromuscular junction due to an autoimmune insult, leading to a compromised neuromuscular transmission. Verapamil can influence, in a dose-dependent fashion, the neuromuscular transmission in myasthenia gravis.</AbstractText>We report a 71-year-old Caucasian man with myasthenia gravis suffering from a cardiogenic shock following a single dose of verapamil. The patient had uncontrolled atrial fibrillation with a heart rate of 120 beats/min. Atenolol 100 mg was started. The next day, verapamil SR 240 mg was started. Two hours after the first dose of verapamil, the patient complained of weakness and dyspnea with signs of shock; his blood pressure was 70/50 mm Hg and heart rate at 101 beats/min. An echocardiogram showed diffuse hypokinesis of both ventricles with an ejection fraction of 20%. Cardiac catheterization was performed and coronary arteries appeared without significant stenosis, but there was a diffuse hypokinesis. Verapamil was stopped and the patient received intravenous glucagon and calcium chloride. Both the anti-acetylcholine receptor and anti-striated muscle antibodies tested positive. A few hours later, another echocardiogram showed an improvement in the ventricular function, which returned to normal five days later.</AbstractText>Caution is needed when administering verapamil to patients with myasthenia gravis, especially when the anti-acetylcholine receptor and anti-striated muscle antibodies titres are positive.</AbstractText> |
6,206 | Short QT syndrome: a review. | The past 2 decades have witnessed the emergence of many disease states related to ion-channel disorders, the so-called "channelopathies," usually associated with structurally normal hearts. The initial emphasis was directed toward the congenital long QT syndrome and the Brugada syndrome. Recently, the hereditary short QT syndrome has emerged as yet another rare channelopathy. This autosomal dominant syndrome can afflict infants, children, or young adults; often a remarkable family background of sudden cardiac death is elucidated. The electrocardiogram is characterized by a strikingly short QT interval (typically <320 milliseconds); virtual absence of the ST segment; and tall, peaked, narrow-based T waves. There is a marked propensity for paroxysmal atrial fibrillation, and increased risk for sudden cardiac death from ventricular tachyarrhythmias. At electrophysiology study, short atrial and ventricular refractory periods are found, with easily inducible atrial fibrillation and polymorphic ventricular tachycardia with programmed electrical stimulation. Gain-of-function mutations in 3 genes encoding potassium channels have been identified, which explain the abbreviated repolarization seen in this condition. The suggested treatment is an implantable cardioverter-defibrillator, though the possibilities of inappropriate shocks have caused some concern, especially in younger patients. The ability of quinidine and disopyramide to prolong the QT interval has the potential to be effective pharmacological therapy for patients with short QT syndrome, but awaits additional confirmatory clinical data. |
6,207 | 'Orphan drugs' in cardiology: nadolol and quinidine. | The recent withdrawal from the market of nadolol (Corgard; Bristol-Myers Squibb, Sermoneta, Italy) and quinidine polygalacturonate (Ritmocor; Malesci, Bagno A Ripoli, Italy) has been causing clinical problems to many cardiologists and patients, frequently leading to discontinuance of an effective and well-tolerated pharmacological treatment. Nadolol is useful in the treatment of severe and refractory arrhythmias, particularly in some genetically determined ion-channel diseases, such as long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia.Quinidine is still used in refractory atrial fibrillation recurrences. Recent studies have demonstrated the clinical efficacy of quinidine in the treatment of rare genetically determined ion-channel diseases at high risk of sudden death, such as Brugada syndrome and short-QT syndrome.We hope that scientific societies can influence healthcare and pharmaceutical institutions, in order to restore the availability of two cardiovascular drugs that are extremely important in the care of arrhythmic patients. |
6,208 | Cardiac-specific deletion of LKB1 leads to hypertrophy and dysfunction. | LKB1 encodes a serine/threonine kinase, which functions upstream of the AMP-activated protein kinase (AMPK) superfamily. To clarify the role of LKB1 in heart, we generated and characterized cardiac myocyte-specific LKB1 knock-out (KO) mice using alpha-myosin heavy chain-Cre deletor strain. LKB1-KO mice displayed biatrial enlargement with atrial fibrillation and cardiac dysfunction at 4 weeks of age. Left ventricular hypertrophy was observed in LKB1-KO mice at 12 weeks but not 4 weeks of age. Collagen I and III mRNA expression was elevated in atria at 4 weeks, and atrial fibrosis was seen at 12 weeks. LKB1-KO mice displayed cardiac dysfunction and atrial fibrillation and died within 6 months of age. Indicative of a prohypertrophic environment, the phosphorylation of AMPK and eEF2 was reduced, whereas mammalian target of rapamycin (mTOR) phosphorylation and p70S6 kinase phosphorylation were increased in both the atria and ventricles of LKB1-deficient mice. Consistent with vascular endothelial growth factor mRNA and protein levels being significantly reduced in LKB1-KO mice, these mice also exhibited a reduction in capillary density of both atria and ventricles. In cultured cardiac myocytes, LKB1 silencing induced hypertrophy, which was ameliorated by the expression of a constitutively active form AMPK or by treatment with the inhibitor of mTOR, rapamycin. These findings indicate that LKB1 signaling in cardiac myocytes is essential for normal development of the atria and ventricles. Cardiac hypertrophy and dysfunction in LKB1-deficient hearts are associated with alterations in AMPK and mTOR/p70S6 kinase/eEF2 signaling and with a reduction in vascular endothelial growth factor expression and vessel rarefaction. |
6,209 | [Cryothermal energy: a new perspective for interventional therapy of cardiac arrhythmias?]. | Cryothermal ablation is a new method in cardiac electrophysiology for the percutaneous catheter ablation of cardiac arrhythmias. Cryothermal mapping make possible the functional assessment of a particular site before permanent ablation. In this way the targeted tissue may be confirmed as safe for ablation. This is useful in high-risk ablation, for example next to the AV node. In this method pressurized liquid nitrogen is delivered to the tip of the ablation catheter. Cooling of the tip is temperature-controlled. Cryothermal balloons are also available, in addition to standard cryothermal catheters, for the isolation of pulmonary veins. The tissue freezing provides high catheter stability. Cryothermal lesions have a similar depth to radiofrequency energy, but area and volume of the lesions are reduced. Furthermore, they are well demarkated and the incidence of thrombus-formation is reduced. Cryothermal ablation has been evaluated for the treatment of AV-nodal reentry tachycardia (AVNRT), accessory pathways, atrial flutter, atrial fibrillation and ventricular tachycardias originating in the right ventricular outflow tract. Current experience indicates that the method is painless for the patient and safe. However, its use seems to be limited by a longer ablation time and lower efficacy. Further studies evaluating long-term success of cryothermal ablation are warranted. For high-risk ablations cryothermal energy is helpful and should be used for para-Hisian accessory pathways and difficult cases of AVNRT. It has a widely demonstrated safety profile. The clinical efficacy will have to be evaluated in further studies. |
6,210 | Impact of right ventricular pacing sites on exercise capacity during ventricular rate regularization in patients with permanent atrial fibrillation. | The deleterious effects of right ventricular apical (RVA) pacing may offset the potential benefit of ventricular rate (VR) regularization and rate adaptation during an exercise in patient's atrial fibrillation (AF).</AbstractText>We studied 30 patients with permanent AF and symptomatic bradycardia who receive pacemaker implantation with RVA (n = 15) or right ventricular septal (RVS, n = 15) pacing. All the patients underwent an acute cardiopulmonary exercise testing using VVI-mode (VVI-OFF) and VVI-mode with VR regularization (VRR) algorithm on (VVI-ON).</AbstractText>There were no significant differences in the baseline characteristics between the two groups, except pacing QRS duration was significantly shorter during RVS pacing than RVA pacing (138.9 +/- 5 vs 158.4 +/- 6.1 ms, P = 0.035). Overall, VVI-ON mode increased the peak exercise VR, exercise time, metabolic equivalents (METs), and peak oxygen consumption (VO(2)max), and decreased the VR variability compared with VVI-OFF mode during exercise (P < 0.05), suggesting that VRR pacing improved exercise capacity during exercise. However, further analysis on the impact of VRR pacing with different pacing sites revealed that only patients with RVS pacing but not patients with RVA pacing had significant increased exercise time, METs, and VO(2)max during VVI-ON compared with VVI-OFF, despite similar changes in peaked exercise VR and VR variability.</AbstractText>In patients with permanent AF, VRR pacing at RVS, but not at RVA, improved exercise capacity during exercise.</AbstractText> |
6,211 | The effect of oral methadone on the QTc interval in advanced cancer patients: a prospective pilot study. | Recent reports suggest that high doses of methadone may prolong QTc interval and occasionally cause torsades de pointes; however, few of these studies involved the palliative care population.</AbstractText>The purpose of this study was to determine the effect of initiation of methadone on QTc interval in patients with cancer pain seen at the palliative care setting.</AbstractText>We enrolled 100 patients with cancer in this prospective study. Patients were followed clinically and electrocardiographically for QTc changes at baseline, 2, 4, and 8 weeks. Contributing factors for QTc prolongation such as medications, cardiovascular diseases, and electrolytes disturbances were documented. QTc prolongation was defined as greater than 430 ms in males and greater than 450 ms in females, and significant QTc prolongation was defined as QTc interval greater than 25% increase from baseline or 500 ms or more.</AbstractText>Electrocardiographic (ECG) assessments were available for 100, 64, 41, and 27 patients at baseline, 2-, 4-, and 8-week follow-up, respectively. At baseline prior to initiation of methadone, 28 (28%) patients had QTc prolongation. Clinically significant increase in QTc occurred in only 1 of 64 (1.6%) patients at week 2, and none at weeks 4 and 8. There was no clinical evidence of torsades de pointes, ventricular fibrillation, or sudden death. QTc prolongation was more frequent among patients with increased baseline QTc interval.</AbstractText>Baseline QTc prolongation was common, whereas significant QTc interval 500 ms or more after methadone initiation rarely occurred, with no evidence of clinically significant arrhythmias. This study supports the safety of methadone use for pain control in patients with advanced cancer in the palliative care setting.</AbstractText> |
6,212 | Safety of symptom-limited cardiopulmonary exercise testing in patients with chronic heart failure due to severe left ventricular systolic dysfunction. | To assess the safety of symptom-limited exercise testing in patients with New York Heart Association class II-IV heart failure symptoms due to left ventricular systolic dysfunction, we investigated the frequency of all-cause fatal and nonfatal major cardiovascular (CV) events among subjects enrolled in a prospective clinical trial (HF-ACTION). We hypothesized that exercise testing would be safe, as defined by a rate for all-cause death of <0.1 per 1,000 tests and a rate of nonfatal CV events <1.0 per 1,000 tests.</AbstractText>Before enrollment and at 3, 12, and 24 months after randomization, subjects were scheduled to complete a symptom-limited graded exercise test with open-circuit spirometry for analysis of expired gases. To ensure the accurate reporting of exercise test-related events, we report deaths and nonfatal major CV events per 1,000 tests at months 3, 12, or 24 after randomization.</AbstractText>A total of 2,331 subjects were randomized into HF-ACTION. After randomization, 2,037 subjects completed 4,411 exercise tests. There were no test-related deaths, exacerbation of heart failure or angina requiring hospitalization, myocardial infarctions, strokes, or transient ischemic attacks. There was one episode each of ventricular fibrillation and sustained ventricular tachycardia. There were no exercise test-related implantable cardioverter defibrillator discharges requiring hospitalization. These findings correspond to zero deaths per 1,000 exercise tests and 0.45 nonfatal major CV events per 1,000 exercise tests (95% CI 0.11-1.81).</AbstractText>In New York Heart Association class II-IV patients with severe left ventricular systolic dysfunction, we observed that symptom-limited exercise testing is safe based on no deaths and a rate of nonfatal major CV events that is <0.5 per 1,000 tests.</AbstractText> |
6,213 | Electromagnetic interference of communication devices on ECG machines. | Use of communication devices in the hospital environment remains controversial. Electromagnetic interference (EMI) can affect different medical devices. Potential sources for EMI on ECG machines were systematically tested.</AbstractText>Communication devices produce EMI on ECG machines. EMI impairs ECG interpretation.</AbstractText>The communication devices tested were: a global system for mobile communication (GSM) receiver, a code division multiple access (CDMA) receiver, an analog phone, a wireless local area network, and an alpha-numeric pager. EMI was tested on 3 ECG machines: MAC 5000, MAC 1200, and ELI 100. The devices were tested at 2 and 1 meter, 50, 25, and 0 cm from the acquisition module. The ECGs were presented to a heterogeneous group of clinical providers, (medical students, residents, nurses, industry representatives from cardiac devices companies, and attending cardiologists) to evaluate the impact of EMI on ECG interpretation skills.</AbstractText>EMI was detected on the MAC 5000 ECG machine when activated GSM, CDMA, and analog phones were placed on top of the acquisition module. No EMI was seen on the other ECG machines or when phones were at a longer distance or deactivated. EMI was incorrectly diagnosed in 18% of the cases. EMI was confused most frequently with atrial fibrillation or flutter (52%), ventricular arrhythmias (22%), and pacemaker dysfunction (26%). Medical students (p < 0.003) and non-cardiology residents (p = 0.05) demonstrated significantly worse performance on EMI interpretation.</AbstractText>Digital and analog phones produce EMI on modern ECG machines when activated in direct contact to the acquisition module. EMI impairs ECG interpretation.</AbstractText> |
6,214 | Effect of global ischemia and reperfusion during ventricular fibrillation in myopathic human hearts. | The effect of lack of global coronary perfusion on myocardial activation rate, wavebreak, and its temporal progression during human ventricular fibrillation (VF) is not known. We tested the hypothesis that global myocardial ischemia decreases activation rate and spatiotemporal organization during VF in myopathic human hearts, while increasing wavebreak, and that a short duration of reperfusion can restore these spatiotemporal changes to baseline levels. The electrograms were acquired during VF in a human Langendorff model using global mapping consisting of two 112-electrode arrays placed on the epicardium and endocardium simultaneously. We found that global myocardial ischemia results in slowing of the global activation rate (combined endo and epi), from 4.89+/-0.04 Hz. to 3.60+/-0.04 Hz. during the 200 s of global ischemia (no coronary flow) (P<0.01) in eight myopathic hearts. Two minutes of reperfusion contributed to reversal of the slowing with activation rate value increasing close to VF onset (4.72+/-0.04 Hz). In addition, during the period of ischemia, an activation rate gradient between the endocardium (3.76+/-0.06 Hz) and epicardium (3.45+/-0.06 Hz) was observed (P<0.01). There was a concomitant difference in wavebreak index (that provides a normalized parameterization of phase singularities) between the epicardium (11.29+/-2.7) and endocardium (3.25+/-2.7) during the 200 s of ischemia (P=0.02). The activation rate, gradient, and wavebreak changes were reversed by short duration (2 min) of reperfusion. Global myocardial ischemia of 3 min leads to complex spatiotemporal changes during VF in myopathic human hearts; these changes can be reversed by a short duration of reperfusion. |
6,215 | [Recurrent refractory ventricular fibrillation: how many times is it necessary to defibrillate?]. | Recurrent ventricular fibrillation is that which persists after three consecutive defibrillation attempts. It generally appears in almost 25% of all heart arrests and entails high mortality. Use of amiodarone during resuscitation maneuvers is recommended, this having better results than lidocaine. Neither procainamide nor bretylium should be used in this type of arrhythmia, however beta blockers or magnesium can be used when ischemic heart disease or hypomagnesiemia, respectively, is suspected as the cause. We present the case of a male patient with a background of heart disease (stent in circunflex 8 years earlier) that began with an episode of primary ventricular fibrillation when entering the Emergency Service. He was given 35 shocks of 360 J, without using thoracic compressions at any time since he recovered an effective post-shock pulse with normal neurological condition. Amiodarone and thrombolytics (tenecteplase) were administered during the intervention, achieving favorable resolution after 52 min, once stabilized showing an electrocardiogram of acute coronary syndrome without ST elevation and verifying obstruction of the right coronary artery in the catheterism, on which a stent was placed. He was discharged from the hospital six days after with no neurological sequels. In agreement with the 2005 International Liaison Committee on Resuscitation Recommendations, the resuscitation maneuvers and electrical shocks should be continued while there is a defibrillable rhythm, as occurred in our patient. |
6,216 | Ethyl pyruvate enhances intra-resuscitation hemodynamics in prolonged ventricular fibrillation arrest. | As the duration of untreated cardiac arrest increases, the effectiveness of standard therapies declines, and may be more harmful than helpful. We investigated the hemodynamic, metabolic and anti-inflammatory effects of Ringer's ethyl pyruvate solution (REPS) versus Ringer's solution (RS) in the acute model of prolonged porcine arrest.</AbstractText>Seventeen mixed-breed swine were induced into ventricular fibrillation (VF) and left untreated for 8min. CPR was begun using a mechanical chest compression device at a rate of 100 per minute. At the onset of CPR, animals were randomly assigned to treatment with either 25mL/kg of RS or 25mL/kg of REPS containing 40mg/kg of ethyl pyruvate, infused over 5min in blinded fashion. CPR continued with administration of a drug cocktail at 2min and the first rescue shock was delivered at minute 13 of VF. Animals having ROSC were supported with standardized care for 2h.</AbstractText>Both groups had 100% ROSC and 100% 2-h survival. The REPS group exhibited higher median CPP (27.3mmHg) than the control group (16.5mmHg) by 3min of CPR, which continued throughout the duration of CPR (p=0.02). The median time to hypotension following ROSC was 9.64min in the REPS group and 7.25min in controls (p=0.04) and there was a non-significant trend of decreased use of vasopressors for the duration of resuscitation. There was no difference in systemic or cerebral metabolism between groups. There were non-significant trends of decreased IL-6, increased Il-10 and decreased mesenteric bacterial colony growth in those treated with REPS when compared to RS.</AbstractText>The administration of REPS with CPR significantly improved intra- and post-resuscitation hemodynamics in this swine model of prolonged cardiac arrest, but did not definitely change the metabolic or inflammatory profile during the acute resuscitation period.</AbstractText> |
6,217 | Vanoxerine, a new drug for terminating atrial fibrillation and flutter. | Vanoxerine produces potent block of cardiac hERG, sodium, and L-type calcium channels. Block is strongly frequency dependent, is unassociated with transmural dispersion of repolarization, and occurs at concentrations safe in humans. Therefore, we proposed that vanoxerine might be antiarrhythmic. In these studies, we tested the hypothesis that vanoxerine would terminate induced atrial fibrillation (AF) and atrial flutter (AFL) in dogs with sterile pericarditis (SP).</AbstractText>In 9 SP dogs, 11 episodes each of sustained (>10 minutes) AF and AFL were induced. Electrophysiological studies were performed before and after infusion of vanoxerine, which effectively terminated AF and AFL in 19 of 22 episodes. Simultaneous multisite mapping during 3 AF and 3 AFL episodes demonstrated that termination of each arrhythmia occurred with termination of the driver (a reentrant circuit) following an increase in tachycardia CL. Except for conduction in an area of slow conduction in the driver's reentrant circuit, vanoxerine did not significantly affect intraatrial or atrioventricular conduction time, QRS duration, or QT/QTc intervals. Ventricular refractoriness prolonged minimally during ventricular pacing at 400 and 333 ms (176 +/- 16 ms to 182 +/- 16 ms; 173 +/- 11 ms to 178 +/- 18 ms, respectively). Vanoxerine minimally increased (mean 0.7 mA) atrial stimulus threshold for capture.</AbstractText>Vanoxerine effectively terminated induced, sustained AF and AFL in the canine SP model, and produced insignificant or minimal changes in refractoriness, conduction time, or stimulus threshold, consistent with little proarrhythmic risk.</AbstractText> |
6,218 | Vanoxerine: cellular mechanism of a new antiarrhythmic. | There remains an unmet need for safe and effective antiarrhythmic drugs, especially for the treatment of atrial fibrillation. Vanoxerine is a drug that is free of adverse cardiac events in normal volunteers, yet is a potent blocker of the hERG (hK(v)11.1) cardiac potassium channel. Consequently,we hypothesized that vanoxerine might also be a potent blocker of cardiac calcium (Ca) and sodium (Na) currents, and would not affect transmural dispersion of repolarization.</AbstractText>The whole cell patch clamp technique was used to measure currents from cloned ion channels overexpressed in stable cell lines and single ventricular myocytes. We measured intracellular action potentials from canine ventricular wedges and Purkinje fibers using sharp microelectrode technique.</AbstractText>We found that vanoxerine was a potent hK(v)11.1 blocker, and at submicromolar concentrations, it blocked Ca and Na currents in a strongly frequency-dependent manner. In the canine ventricular wedge preparation vanoxerine did not significantly affect transmural action potential waveforms, QT interval or transmural dispersion of repolarization.</AbstractText>Vanoxerine (1) is a potent blocker of cardiac hERG, Na and Ca channels; (2) block is strongly frequency-dependent especially for Na and Ca channels; and (3) transmural dispersion of ventricular repolarization is unaffected. The multichannel block and repolarization uniformity resemble the effects of amiodarone, the exemplar atrial fibrillation drug. Vanoxerine is a completely different chemical and has none of amiodarone's toxic effects. Vanoxerine has characteristics of a potentially effective and safe antiarrhythmic.</AbstractText> |
6,219 | Long-term outcomes of inducible very fast ventricular tachycardia (cycle length 200-250 ms) in patients with ischemic cardiomyopathy. | The long-term outcomes of patients with inducible very fast ventricular tachycardia (VFVT) of cycle length (CL) 200 to 250 ms have not been well studied.</AbstractText>Consecutive patients with ischemic cardiomyopathy with a left ventricular ejection fraction (LVEF) of <or=40% (n = 300) underwent programmed ventricular stimulation (PVS) and were divided into 4 groups based on results of the study. Group A were noninducible, had induced ventricular fibrillation (VF), or polymorphic VT (CL < 200 ms); group B had inducible VFVT (200-250 ms); group C had inducible fast ventricular tachycardia (FVT; CL 251-320 ms); and group D had inducible slow VT (CL >320 ms). The primary endpoint was spontaneous ventricular arrhythmia or sudden death.</AbstractText>The mean age was 63 +/- 12 years and mean LVEF was 29 +/- 7%. At mean follow-up of 38 +/- 25 months (median 30 months), the primary endpoint rate was 6.6%, 34%, 44%, and 71% in groups A, B C, and D, respectively (P < 0.001). Neither mode of induction of VT nor LVEF altered the observed pattern in the primary endpoint. There was no significant difference in the primary endpoint among implanted cardioverter defibrillator recipients in groups B and C (38% vs 45%, P = 0.43). Adjusted hazard ratios for the primary endpoint compared to group A were 3.2, 3.5, and 7.0 in groups B, C, and D, respectively (P < 0.05).</AbstractText>Inducible VFVT (200-250 ms) is a clinically significant arrhythmia with adverse long-term outcomes and should not be considered a nonspecific finding of PVS.</AbstractText> |
6,220 | A new electrocardiographic algorithm to locate the occlusion in left anterior descending coronary artery. | Early prediction of proximal left anterior descending coronary artery (LAD) occlusion is essential from a clinical point of view</AbstractText>To develop an electrocardiogram (ECG) algorithm based on ST-segment deviations to predict the location of occlusion of LAD as a culprit artery.</AbstractText>ECG and angiographic findings were correlated in 100 patients with an ST-segment elevation myocardial infarction (MI) in precordial leads V(1), V(2), and V(4) through V(6).</AbstractText>ST-depression > or = 2.5 mm in leads III + ventricular fibrillation (VF) presents sensitivity (SE) of 77% and specificity (SP) of 84% for LAD occlusion proximal to the first diagonal artery (D1). ST-segment in III + VF isoelectric or elevated, presents SE of 44% and SP of 100% for LAD occlusion distal to D1. Subsequent analysis of the equation summation operator of ST-deviation in VR + V(1) - V(6) < 0, allows us to predict occlusion distal to first septal artery (S1) with 100% SP. On the other hand, any ST-depression in III + VF > 0.5 mm + summation operator of ST-deviation in VR + V(1) - V(6) > or = 0 identifies a high-risk group (lower ejection fraction, worse Killip findings, higher peak of CPK and CK-MB, and major adverse cardiac events [MACE]: death, reinfarction, recurrent angina, persistent left ventricular failure, or sustained ventricular arrhythmia during hospitalization).</AbstractText>This sequential ECG algorithm based on ST-segment deviations in different leads allowed us to predict the location of occlusion in LAD with good accuracy. Cases with proximal LAD occlusion present the most markers of poor prognosis. We recommend the use of the algorithm in everyday clinical practice.</AbstractText> |
6,221 | Alendronate affects calcium dynamics in cardiomyocytes in vitro. | Therapy with bisphosphonates, including alendronate (ALN), is considered a safe and effective treatment for osteoporosis. However, recent studies have reported an unexpected increase in serious atrial fibrillation (AF) in patients treated with bisphosphonates. The mechanism that explains this side effect remains unknown. Since AF is associated with an altered sarcoendoplasmic reticulum calcium load, we studied how ALN affects cardiomyocyte calcium homeostasis and protein isoprenylation in vitro. Acute and long-term (48h) treatment of atrial and ventricular cardiomyocytes with ALN (10(-8)-10(-6)M) was performed. Changes in calcium dynamics were determined by both fluorescence measurement of cytosolic free Ca(2+) concentration and western blot analysis of calcium-regulating proteins. Finally, effect of ALN on protein farnesylation was also identified. In both atrial and ventricular cardiomyocytes, ALN treatment delayed and diminished calcium responses to caffeine. Only in atrial cells, long-term exposure to ALN-induced transitory calcium oscillations and led to the development of oscillatory component in calcium responses to caffeine. Changes in calcium dynamics were accompanied by changes in expression of proteins controlling sarcoendoplasmic reticulum calcium. In contrast, ALN minimally affected protein isoprenylation in these cells. In summary, treatment of atrial cardiomyocytes with ALN-induced abnormalities in calcium dynamics consistent with induction of a self-stimulatory, pacemaker-like behavior, which may contribute to the development of cardiac side effects associated with these drugs. |
6,222 | Effect of mitral regurgitation on cerebrovascular accidents in patients with atrial fibrillation and left atrial thrombus. | The effect of mitral regurgitation (MR) on the incidence of new cerebrovascular accidents (CVA) and mortality in patients with atrial fibrillation (AF) and left atrial thrombus (LAT) is unknown.</AbstractText>To investigate the effect of MR in patients with AF and LAT on new CVA and mortality.</AbstractText>Eighty nine consecutive patients, mean age 71 years, with AF and LAT documented by transesophageal echocardiography were investigated to determine the prevalence and severity of MR and the association of the severity of MR with new cerebrovascular accidents (CVA) and mortality at 34-mo follow-up.</AbstractText>Of 89 patients, 1 + MR was present in 23 patients (26%), 2 + MR in 44 patients (50%), 3 + MR in 17 patients (19%), and 4 + MR in 3 patients (4%). Mean follow-up was 34 +/- 28 mo. The Cox proportional hazards model showed that the severity of increased MR did not significantly increase new CVA or mortality at 34-mo follow-up. The only variable predictive of mortality was left ventricular ejection fraction (LVEF), and with every unit increase in LVEF, the risk decreased by 3%.</AbstractText>MR occurred in 87 of 89 patients (98%) with AF and LAT. There was no association between the severity of MR and the incidence of CVA or mortality.</AbstractText> |
6,223 | A servo-controlled canine model of stable severe ischemic left ventricular failure. | Reversible left ventricular failure was produced in conscious dogs by compromise of the coronary circulation. In animals with prior left anterior descending coronary artery occlusion, mean left atrial pressure (LAP) was incorporated into an automatic feedback control system used to inflate a balloon cuff on the circumflex (Cfx) coronary artery. The system could produce stable increases in LAP to 15-20 mm Hg. The dominating system transfer function was the ratio of LAP to balloon volume (BV), which was characterized by a fixed delay (5 s), with LAP/BV = (8e(-jomegatau ))/(0.02 + jomega). The system was stabilized by a phase lead network to reduce oscillations of LAP. A total of seven experiments were conducted in three dogs, and testing of inotropic agents was possible in three experiments under stable conditions with the pump off after an hour or more of operation. Problems encountered were 0.003-0.008 Hz oscillations in LAP in three experiments, which could usually be controlled by reducing the system gain. Late stage ventricular fibrillation occurred in all three animals, but defibrillation was easily accomplished after deflating the Cfx balloon. This system produces reversible left ventricular failure solely due to ischemia, thus closely simulating clinical heart failure due to coronary insufficiency. |
6,224 | A sweet tooth as the root cause of cardiac arrest. | A 71-year-old woman was admitted with hypotension and bradycardia. An electrocardiogram showed flattened T waves and increased U wave prominence, resulting in a long QT(U) syndrome. Her initial serum potassium level was 1.6 mmol/L (all other electrolytes, including magnesium, were normal). She suffered recurrent ventricular tachycardia and ventricular fibrillation arrest requiring direct current cardioversion and high-dose intravenous potassium chloride replacement. Systematic enquiry revealed that she had been constipated for a number of months and had resorted to consuming large quantities of liquorice on a daily basis for its laxative effects. Endocrinology review identified no primary abnormality of the renin- angiotensin- aldosterone axis, and the patient was diagnosed with hypokalemia secondary to liquorice overindulgence. Liquorice has a mineralocorticoid effect. If chronically consumed in large quantities, this effect may lead to severe depletion of whole-body potassium stores. The present case highlights a rare but important cause of hypokalemic cardiac arrest of which all acute care physicians should be aware.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Crean</LastName><ForeName>Andrew M</ForeName><Initials>AM</Initials><AffiliationInfo><Affiliation>Department of Cardiology, Toronto General Hospital, Toronto, Ontario. [email protected]</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Abdel-Rahman</LastName><ForeName>Saif-El-Dean T</ForeName><Initials>SE</Initials></Author><Author ValidYN="Y"><LastName>Greenwood</LastName><ForeName>John Pierre</ForeName><Initials>JP</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>England</Country><MedlineTA>Can J Cardiol</MedlineTA><NlmUniqueID>8510280</NlmUniqueID><ISSNLinking>0828-282X</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000368" MajorTopicYN="N">Aged</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004562" MajorTopicYN="N">Electrocardiography</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006035" MajorTopicYN="N">Glycyrrhiza</DescriptorName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006323" MajorTopicYN="N">Heart Arrest</DescriptorName><QualifierName UI="Q000175" MajorTopicYN="N">diagnosis</QualifierName><QualifierName UI="Q000209" MajorTopicYN="Y">etiology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D007008" MajorTopicYN="N">Hypokalemia</DescriptorName><QualifierName UI="Q000139" MajorTopicYN="Y">chemically induced</QualifierName><QualifierName UI="Q000150" MajorTopicYN="Y">complications</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D008133" MajorTopicYN="N">Long QT Syndrome</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="Y">complications</QualifierName><QualifierName UI="Q000175" MajorTopicYN="N">diagnosis</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D010946" MajorTopicYN="N">Plants, Medicinal</DescriptorName></MeshHeading></MeshHeadingList><OtherAbstract Type="Publisher" Language="fre">Une femme de 71 ans a été hospitalisée en raison d’une hypotension et d’une bradycardie. L’électrocardiogramme a démontré des ondes T aplaties et une proéminence accrue des ondes U, entraînant un syndrome du QT(U) long. Son taux de potassium sérique initial était de 1,6 mmol/L (tous les autres électrolytes, y compris le magnésium, étaient normaux). Elle souffrait d’une tachycardie ventriculaire récurrente et d’un arrêt de la fibrillation auriculaire qui a exigé une cardioversion et un traitement de substitution à fortes doses de chlorure potassique intraveineux. Une exploration systématique a révélé que la femme était constipée depuis plusieurs mois et qu’elle avait recouru à une importante consommation quotidienne de réglisse en raison de ses effets laxatifs. Le bilan endocrinologique n’a révélé aucune anomalie primaire de l’axe rénine-angiotensine-aldostérone, et la patiente a obtenu un diagnostic d’hypocalcémie secondaire à une surconsommation de réglisse. La réglisse a un effet minéralocorticoïde. S’il est consommé de manière chronique en grandes quantités, il peut être responsable d’une grave déplétion des réserves totales de potassium. Le présent cas faire ressortir une cause rare mais importante d’arrêt cardiaque hypocalcémique que tous les médecins de soins aigus devraient connaître. |
6,225 | Prophylactic amiodarone versus lidocaine for prevention of reperfusion ventricular fibrillation after release of aortic cross-clamp. | Ventricular fibrillation is common after aortic cross-clamp release in patients undergoing open-heart surgeries. The aim of the study was to evaluate the efficacy of the prophylactic administration of 150 mg amiodarone by way of the pump 2 min before release of aortic cross-clamp in preventing ventricular fibrillation.</AbstractText>The present study is a prospective, randomized, controlled and blinded study performed at a teaching university hospital where 120 patients undergoing coronary bypass graft surgery were randomly assigned to three groups. Each group received either 150 mg of amiodarone or 100 mg lidocaine or isotonic saline by way of pump 2 min before release of the aortic cross-clamp. The frequency of occurrence of ventricular fibrillation and the subsequent required defibrillation counter shocks were determined in all groups.</AbstractText>The frequency of occurrence of ventricular fibrillation was significantly higher in both the amiodarone (48%) and the control group (45%) as compared with the lidocaine group (20%) with no statistically significant difference between the amiodarone and the control groups. Furthermore, when ventricular fibrillation occurred, the percentage of patients requiring defibrillation counter shocks was significantly higher in both the amiodarone (58%) and control (61%) groups as compared with the lidocaine group (13%) with no difference between the amiodarone and the control groups, despite a significant decrease in the defibrillation counter shocks energy requirements in the amiodarone group.</AbstractText>The present study showed no difference between amiodarone (150 mg) and placebo in preventing ventricular fibrillation after release of aortic cross-clamp. In addition, the use of lidocaine was able to reduce the incidence of ventricular fibrillation as compared with both amiodarone and placebo.</AbstractText> |
6,226 | Simultaneous right and left coronary occlusion caused by an extensive dissection to the coronary sinus of Valsalva during percutaneous intervention in right coronary artery. | We report a case of simultaneous right and left coronary occlusion during percutaneous coronary intervention in the right coronary artery. An aortocoronary dissection induced by the forceful manipulation extended from the right to left sinus of Valsalva and occluded the ostia of both coronary arteries. The patient suffered cardiogenic shock and ventricular fibrillation. However, after successful rapid stenting to right and left coronary arteries, safe discharge was possible. |
6,227 | Cardiac metabolism and arrhythmias. | Sudden cardiac death remains a leading cause of mortality in the Western world, accounting for up to 20% of all deaths in the U.S., The major causes of sudden cardiac death in adults age 35 and older are coronary artery disease (70–80%) and dilated cardiomyopathy (10–15%). At the molecular level, a wide variety of mechanisms contribute to arrhythmias that cause sudden cardiac death, ranging from genetic predisposition (rare mutations and common polymorphisms in ion channels and structural proteins) to acquired electrophysiological and structural remodeling in left ventricular hypertrophy and failure., A growing body of evidence suggests that altered ion channel function is closely linked to changes in metabolic activity in a wide variety of pathological conditions. In this review we focus on the mechanisms by which altered metabolic function impacts cardiac electrophysiology. We will review the specific molecular targets that allow cardiomyocytes to recognize alterations in their metabolic state and translate this information into changes in membrane excitability in various pathophysiological conditions including ischemia-reperfusion, heart failure (HF), left ventricular hypertrophy, diabetic cardiomyopathy and atrial fibrillation. A comprehensive understanding of the interrelated processes of metabolic and electrical remodeling promises to identify new molecular targets for the treatment of cardiac arrhythmias. |
6,228 | Prediction of ventricular tachyarrhythmias by intracardiac repolarization variability analysis. | Arrhythmic sudden cardiac death (SCD) is generally mediated by ventricular fibrillation (VF) or fast ventricular tachycardia (FVT). We studied the predictive value of temporal QT variability detected from various sources of cardiac electric signal: surface ECG, far-field (FF), and near-field (NF) intracardiac electrograms (EGMs) in patients with implantable cardioverter-defibrillators (ICDs).</AbstractText>Surface ECG and FF and NF intracardiac EGMs were simultaneously recorded at rest (mean heart rate, 74+/-15 bpm) for 4.5+/-1.3 minutes in 298 patients (mean age, 59+/-14; 216 male [73%]) with structural heart disease and an implanted Medtronic ICD for primary (231 patients, 78%) or secondary (67 patients, 22%) prevention of SCD. During mean follow-up of 16+/-8 months, 52 (13.1% per person-year of follow-up) patients sustained VT/VF and received appropriate ICD therapies, but only 19 (4.8% per person-year of follow-up) patients sustained FVT/VF with cycle length <or=240 ms. The Kaplan-Meier survival analysis showed that the highest QT variability index (QTVI) quartile from all cardiac sources (surface ECG; NF and FF EGMs) is associated with event-free survival (P=0.038 for ECG; P=0.024 for FF EGM; P=0.012 for NF EGM). QTVI was a predictor of all VT/VF events and FVT/VF in the multivariate Cox model (including ischemic or nonischemic cardiomyopathy, history of revascularization procedures, LVEF, New York Heart Association class). Strong significant correlation among QTVI determined from all 3 sources was found.</AbstractText>Repolarization lability is present throughout the ventricular myocardium. Increased intracardiac QT variability predicts VT/VF events in patients with structural heart disease.</AbstractText> |
6,229 | Long-term improvement in left ventricular strain after successful catheter ablation for atrial fibrillation in patients with preserved left ventricular systolic function. | The effect of successful catheter ablation on left ventricular (LV) strain in patients with preserved LV systolic function is unknown. The aim of the present study was to assess the long-term effects of catheter ablation for atrial fibrillation (AF) on LV strain and strain rate in patients with preserved LV ejection fraction.</AbstractText>In 78 patients undergoing catheter ablation for AF, speckle tracking strain imaging was performed to assess LV strain in 3 directions (radial, circumferential, and longitudinal) at baseline and after 12-month follow-up. The study population was divided into 2 groups, according to the maintenance of sinus rhythm (SR) during follow-up. After 13.8+/-4.7 months of follow-up, 54 patients (69%) were in SR (SR group), whereas 24 patients (31%) had recurrence of AF (AF group). No significant changes in LV ejection fraction from baseline to follow-up were noted (60+/-7% versus 59+/-7%, P=NS). Circumferential strain improved significantly in the SR group (-18.3+/-3.2% versus -20.4+/-3.8%, P<0.001), whereas it remained unchanged in the AF group (-18.9+/-3.5% versus -17.9+/-3.1%, P=NS). In the SR group, significant improvements in LV longitudinal strain and strain rate were noted, whereas in the AF group, LV longitudinal strain and strain rate deteriorated significantly at long-term follow-up.</AbstractText>After successful catheter ablation, LV circumferential and longitudinal strain and strain rate improve significantly in patients who maintain SR. In contrast, a decrease in LV longitudinal strain and strain rate is observed in patients with recurrence of AF.</AbstractText> |
6,230 | Preshock cardiopulmonary resuscitation worsens outcome from circulatory phase ventricular fibrillation with acute coronary artery obstruction in swine. | Some clinical studies have suggested that chest compressions before defibrillation improve survival in cardiac arrest because of prolonged ventricular fibrillation (VF; ie, within the circulatory phase). Animal data have also supported this conclusion, and we have previously demonstrated that preshock chest compressions increase the VF median frequency and improve the likelihood of a return of spontaneous circulation in normal swine. We hypothesized that chest compressions before defibrillation in a swine model of acute myocardial ischemia would also increase VF median frequency and improve resuscitation outcome.</AbstractText>Twenty-six swine were subjected to balloon occlusion of the left anterior descending coronary artery for 2 hours. The balloon was removed and VF was induced and untreated for 8 minutes. Swine were then treated with up to 3 stacked defibrillation shocks (n=13, shock-first group) or 3 minutes of chest compressions before shock (n=13, preshock cardiopulmonary resuscitation group). In the preshock cardiopulmonary resuscitation group, median frequency was increased from 7.0+/-0.8 to 13.9+/-1.6 Hz after chest compressions (P=0.002). Despite the improved median frequency in the preshock cardiopulmonary resuscitation group, 24-hour survival with favorable neurological status was significantly worse in the preshock cardiopulmonary resuscitation group (1/13) compared with the shock-first group (8/13, P=0.01).</AbstractText>In a swine model of prolonged VF in acute myocardial ischemia, 24-hour survival with favorable neurological status was more likely when defibrillation was performed first without preceding chest compressions. Myocardial substrate is an important factor in determining the optimal resuscitation strategy.</AbstractText> |
6,231 | Absence of pathognomonic or inflammatory patterns in cardiac biopsies from patients with Brugada syndrome. | Brugada syndrome (BrS) is characterized by the presence of coved ST-segment elevations in the right precordial leads (so-called type I ECG) and additional clinical features. Caused by cardiac ion channel gene mutations, BrS may be associated with ventricular and atrial conduction disturbances as well as ventricular fibrillation. Recent studies have discussed whether BrS is merely a primary electric disorder or whether inflammatory or other histopathologic abnormalities in the right ventricle (RV) underlie the ECG phenotype.</AbstractText>We retrospectively analyzed BrS biopsy samples from 21 unrelated patients for histopathologic abnormalities (hypertrophy, fibrosis, inflammation, fatty tissue) together with the patients' clinical, genetic, and imaging data. Eleven patients (52%) had normal RV imaging (by angiography, echocardiography, or cardiac MRI). Results of myocardial biopsies were normal in 3 patients (14%) and revealed mostly moderate abnormalities in the others. Four patients (19%) had predominant fatty tissue in the RV myocardium. Using immunohistochemistry and conventional tissue staining, we could not detect inflammatory tissue changes, an observation compatible with the clinical absence of signs for myocarditis.</AbstractText>Imaging and histopathologic evaluation may detect moderate but uncharacteristic cardiac abnormalities in patients with BrS. None of the patients had arrhythmogenic RV cardiomyopathy or overt myocarditis. Only in a small subset did predominant histopathologic abnormalities in the biopsy samples of the RV outflow tract occur that could provide a link to the ECG phenotype. A variety of mechanisms, including genetic and structural RV alterations, may underlie the Brugada ECG phenotype.</AbstractText> |
6,232 | Yield of genetic screening in inherited cardiac channelopathies: how to prioritize access to genetic testing. | Identification of mutations in cardiac ion channel genes concurs to the diagnosis of long-QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. However, because availability of genetic screening is still limited and reimbursement policies are lacking, there is a need of evidence-based criteria to prioritize access to genetic testing for these diseases.</AbstractText>We determined the yield of genetic testing and cost per positive genotyping in 1394 consecutive probands. Among the 546 patients referred for long-QT syndrome-genes screening, those with clinical diagnosis of long-QT syndrome had the highest yield (64%) and lowest cost (US $8418) for each positive genotyping. Among 798 individuals screened for mutation on the SCN5A gene, the highest yield was obtained in patients with type 1 Brugada syndrome ECG pattern (51 of 405; 13%) corresponding to a cost of US $21441 per positive genotyping. In conclusive Brugada syndrome patients the presence of atrioventricular block (odds ratio: 3.3, CI: 1.8 to 6.1; P=0.0001) increases the yield (23%) of genotyping and reduces its cost (US $ 11700). Among 175 patients screened on RyR2 gene, those with documented bidirectional ventricular tachycardia had the highest incidence (62%) of mutations and the lowest cost (US $5263) per positive genotyping. Genetic screening of unselected family members of sudden cardiac death victims and idiopathic ventricular fibrillation survivors is largely ineffective (yield of 9%) and costly (US $71430 per 1 positive genotyping).</AbstractText>Genotyping can be performed at reasonable cost in individuals with conclusive diagnosis of long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia, and in patients with type I Brugada syndrome ECG with atrioventricular block. These patients should be given priority to access genetic testing.</AbstractText> |
6,233 | Incidence of atrial fibrillation in relation to changing heart rate over time in hypertensive patients: the LIFE study. | Onset of atrial fibrillation (AF) has been linked to changes in autonomic tone, with increasing heart rate (HR) immediately before AF onset in some patients suggesting a possible role of acute increases in sympathetic activity in AF onset. Although losartan therapy and decreasing ECG left ventricular hypertrophy are associated with decreased AF incidence, the relationship of HR changes over time to development of AF has not been examined.</AbstractText>HR was evaluated in 8828 hypertensive patients without AF by history or on baseline ECG in the Losartan Intervention for End Point Reduction in Hypertension (LIFE) study. Patients were treated with losartan- or atenolol-based regimens and followed with serial ECGs annually which were used to determine HR and ECG left ventricular hypertrophy by Cornell product and Sokolow-Lyon voltage criteria. During mean follow-up of 4.7+/-1.1 years, new-onset AF occurred in 701 patients (7.9%). Patients with new AF had smaller decreases in HR to last in-treatment ECG or last ECG before AF (-2.7+/-13.5 versus -5.2+/-12.5 bpm), whether on losartan- (-0.4+/-13.5 versus -2.2+/-11.7 bpm) or atenolol-based treatment (-5.3+/-12.8 versus -8.3+/-12.6 bpm, all P<0.001). In univariate Cox analyses, higher HR on in-treatment ECGs was associated with an increased risk of new-onset AF, with a 15% greater risk of AF for every 10 bpm higher HR (95% CI 8% to 22%). In alternative analyses, persistence or development of a HR> or =84 (upper quintile of baseline HR) was associated with a 46% greater risk of developing AF (95% CI 19% to 80%). After adjusting for treatment with losartan versus atenolol, baseline risk factors for AF, baseline and in-treatment systolic and diastolic pressure and the known predictive value of baseline and in-treatment ECG left ventricular hypertrophy for new AF, higher in-treatment HR remained strongly associated with new AF with a 19% higher risk for every 10 bpm higher HR (95% CI 10% to 28%) or a 61% increased rate of AF in patients with persistence or development of a HR> or =84 (95% CI 27% to 104%, all P<0.001).</AbstractText>Higher in-treatment HR on serial ECGs is associated with an increased likelihood of new-onset AF, independent of treatment modality, blood pressure lowering, and regression of ECG left ventricular hypertrophy in patients with essential hypertension.</AbstractText> |
6,234 | In a swine model, chest compressions cause ventricular capture and, by means of a long-short sequence, ventricular fibrillation. | During resuscitation, fibrillation often recurs. In swine, we studied refibrillation after long-duration ventricular fibrillation, investigating an association with chest compressions (CCs).</AbstractText>In protocol A, 47 episodes of long-duration ventricular fibrillation lasting at least 2.5 minutes were induced in 8 animals. After defibrillation, CCs were required for 35 episodes and delivered with a pneumatic device (Lucas cardiopulmonary resuscitation). In 9 episodes, refibrillation occurred within 2 seconds of CC initiation (group 1) and in 26 episodes, CCs were delivered without refibrillation (group 2). From the ECG and intracardiac electrodes, the RR interval preceding CCs, the shortest cycle length during the first 2 CCs (short), and the preceding cycle length (long) were measured. A similar study was conducted in 3 more animals without intracardiac catheters (protocol B). In protocol A, the mean RR before CC was 665+/-292 ms in group 1 and 769+/-316 in group 2. CCs stimulated ventricular beats in all 35 episodes. The short and long intervals were shorter in group 1 (215+/-31 and 552+/-210 ms) than in group 2 (402+/-153 and 699+/-147 ms) (P=0.009 and P=0.04, respectively). The prematurity index (short/RR) was lower in group 1 than in group 2 (0.35+/-0.09 vs 0.58+/-0.21; P<0.01). A short interval <231 ms predicted refibrillation with 88% sensitivity and 91% specificity. In protocol B, CCs were required in 11 episodes, causing ventricular stimulation in all of them and ventricular fibrillation within the first 2 CCs in 3.</AbstractText>Under some conditions, CC during resuscitation can stimulate the ventricles and initiate ventricular fibrillation by a long-short sequence.</AbstractText> |
6,235 | Association between elevated fibrosis markers and heart failure in the elderly: the cardiovascular health study. | Myocardial fibrosis reflects excess collagen deposition in the extracellular left ventricular matrix, which has been associated with heart failure (HF). No studies have addressed the relation between fibrosis biomarkers and HF in the elderly.</AbstractText>Serum fibrosis markers were measured in 880 participants of the Cardiovascular Health Study (mean age 77+/-6 years, 48% women). Participants with systolic HF (n=131, left ventricular ejection fraction <55%) and those with diastolic HF (n=179, left ventricular ejection fraction > or =55%) were compared with controls (280 with cardiovascular risk factors, and 279 healthy individuals) using a nested case-control design. Fibrosis markers included carboxyl-terminal peptide of procollagen type I, carboxyl-terminal telopeptide of collagen type I, and amino-terminal peptide of procollagen type III. Echocardiography was used to document systolic and diastolic function parameters. Analysis of variance and logistic regression analysis (per tertile odds ratios [OR]), adjusted by age, gender, race, hypertension, atrial fibrillation, coronary heart disease, baseline serum glucose, serum cystatin C, serum creatinine, C-reactive protein, any angiotensin-converting enzyme inhibitor, spironolactone or any diuretic, NT-proBNP, and total bone mineral density were performed. Systolic HF was associated with significantly elevated carboxyl-terminal telopeptide of collagen type I (OR=2.6; 95% CI=1.2 to 5.7) and amino-terminal peptide of procollagen type III (OR=3.3; 95% CI=1.6 to 5.8), when adjusting for covariates. Associations of diastolic HF were significant for carboxyl-terminal telopeptide of collagen type I (OR=3.9; 95% CI=1.9 to 8.3) and amino-terminal peptide of procollagen type III (OR=2.7; 95% CI=1.4 to 5.4). HF was not associated with elevated carboxyl-terminal peptide of procollagen type I (P>0.10), and fibrosis markers did not significantly differ between HF with diastolic versus those with systolic dysfunction (P>0.10) whereas NT-proBNP mean values were higher in systolic heart failure than in diastolic heart failure (P<0.0001).</AbstractText>Fibrosis markers are significantly elevated in elderly individuals with diastolic or systolic HF. These associations remained significant when adjusting for covariates relevant to the aging process.</AbstractText> |
6,236 | The efficacy of implantable cardioverter-defibrillators in heart transplant recipients: results from a multicenter registry. | Sudden cardiac death among orthotopic heart transplant recipients is an important mechanism of death after cardiac transplantation. The role for implantable cardioverter-defibrillators (ICDs) in this population is not well established. This study sought to determine whether ICDs are effective in preventing sudden cardiac death in high-risk heart transplant recipients.</AbstractText>We retrospectively analyzed the records of all orthotopic heart transplant patients who had ICD implantation between January 1995 and December 2005 at 5 heart transplant centers. Thirty-six patients were considered high risk for sudden cardiac death. The mean age at orthotopic heart transplant was 44+/-14 years, the majority being male (n=29). The mean age at ICD implantation was 52+/-14 years, whereas the average time from orthotopic heart transplant to ICD implant was 8 years +/-6 years. The main indications for ICD implantation were severe allograft vasculopathy (n=12), unexplained syncope (n=9), history of cardiac arrest (n=8), and severe left ventricular dysfunction (n=7). Twenty-two shocks were delivered to 10 patients (28%), of whom 8 (80%) received 12 appropriate shocks for either rapid ventricular tachycardia or ventricular fibrillation. The shocks were effective in terminating the ventricular arrhythmias in all cases. Three (8%) patients received 10 inappropriate shocks. Underlying allograft vasculopathy was present in 100% (8 of 8) of patients who received appropriate ICD therapy.</AbstractText>Use of ICDs after heart transplantation may be appropriate in selected high-risk patients. Further studies are needed to establish an appropriate prevention strategy in this population.</AbstractText> |
6,237 | Digoxin therapy does not improve outcomes in patients with advanced heart failure on contemporary medical therapy. | The impact of digoxin on outcomes of patients with advanced heart failure (HF) receiving optimal contemporary therapy is not known.</AbstractText>We retrospectively reviewed data of 455 advanced HF patients referred for transplant evaluation (age, 52+/-12 years; ejection fraction, 18.3+/-8%); 227 (49.9%) were on digoxin at baseline. Primary outcome was death (n=101), urgent transplantation (n=14), or ventricular assist device implantation (n=4); secondary outcomes included HF and all-cause hospitalizations. Digoxin use was evaluated (1) in the original cohort; (2) in a propensity score-matched subset (n=322); (3) as a time-dependent covariate; and (4) after adjustment for Seattle Heart Failure Score. Patients were on optimal therapy: angiotensin-II modulation, 92.5%; beta-blockers, 91.2%; aldosterone antagonists, 45.6%; and devices, 71.0%. After a median of 27 months, 83 of 277 (36.6%) patients treated with digoxin versus 36 of 228 (15.8%) patients without digoxin met primary outcome (hazard ratio [HR], 2.28; 95% CI, 1.51 to 3.43; P<0.001). This risk persisted in the matched subset (HR, 1.73; 95% CI, 1.09 to 2.75; P=0.021) and with time-varying digoxin use (HR, 2.05; 95% CI, 1.23 to 3.41; P=0.011). Digoxin was associated with higher risk among patients in sinus rhythm compared with atrial fibrillation. Digoxin was not associated with improvement in either all-cause or HF hospitalization rates. These results were similar across sex and race and when adjusted for Seattle Heart Failure Score and renal function.</AbstractText>This study suggests that digoxin therapy may be of no benefit in patients with advanced HF referred for cardiac transplantation who received optimal medical therapy. Treatment with digoxin should be used cautiously in such patients because of risk for adverse outcomes.</AbstractText> |
6,238 | Management of nonvalvular atrial fibrillation: a comprehensive approach. | Atrial fibrillation is the most common arrhythmia in clinical practice, may coexist with conditions common to both cardiovascular and noncardiovascular diseases and is associated with considerable morbidity and mortality. Atrial fibrillation is often asymptomatic and diagnosed only when it has caused a potentially serious complication, such as an ischemic stroke. When atrial fibrillation has been identified, 2 objectives have to be addressed--the antiarrhythmic therapy based on rate control or rhythm control, and prevention of thromboembolism. A rhythm or rate control strategy can be chosen indifferently because they have comparable efficacy for the outcome measure of mortality, but the antithrombotic therapy is ever mandatory. The risk of stroke increases cumulatively with increasing age, previous transient ischemic attack or stroke, hypertension, diabetes mellitus, impaired left ventricular function and heart failure. Warfarin reduces the risk of stroke by about two thirds; and aspirin, by about one fifth, but its use must be weighted with the risk of bleeding. The risk of anticoagulant-associated hemorrhage increases with age, the presence of serious concomitant diseases, with poorly controlled hypertension and poorly controlled anticoagulation. |
6,239 | Induction and maintenance of in vivo ventricular fibrillation in rabbits. | To provide new sustainable in vivo models of ventricular fibrillation in rabbits.</AbstractText>New Zealand rabbits were submitted to anaesthesia and mechanical ventilation, after which ventricular fibrillation was induced through electrical stimulation (for 2min at 100Hz, with 2-ms pulses, 10mA, and 10V) directly to the heart. To that end, the animals were divided into two groups: right ventricle (n=11) and left ventricle (n=11). In group right ventricle, the thoracic cavity was exposed, and a catheter was introduced into the right ventricle via the right jugular vein. In group left ventricle, the thorax remained closed, and the catheter was introduced into the left ventricle via the left common carotid artery (cervical access).</AbstractText>Sustained ventricular fibrillation was achieved in 100% of group right ventricle rabbits (n=11) and in 82% of group left ventricle rabbits (n=9).</AbstractText>Both models proved appropriate for achieving sustained ventricular fibrillation. However, in view of the invasiveness of the procedure adopted in group right ventricle, the experimental conditions used in group left ventricle seemed more physiological and more effective in inducing sustained ventricular fibrillation.</AbstractText> |
6,240 | Predictors of resuscitation outcome in a swine model of VF cardiac arrest: A comparison of VF duration, presence of acute myocardial infarction and VF waveform. | Factors that affect resuscitation to a perfusing rhythm (ROSC) following ventricular fibrillation (VF) include untreated VF duration, acute myocardial infarction (AMI), and possibly factors reflected in the VF waveform. We hypothesized that resuscitation of VF to ROSC within 3min is predicted by the VF waveform, independent of untreated VF duration or presence of acute MI.</AbstractText>AMI was induced by the occlusion of the left anterior descending coronary artery. VF was induced in normal (N=30) and AMI swine (N=30). Animals were resuscitated after untreated VF of brief (2min) or prolonged (8min) duration. VF waveform was analyzed before the first shock to compute the amplitude-spectral area (AMSA) and slope.</AbstractText>Unadjusted predictors of ROSC within 3min included untreated VF duration (8min vs 2min; OR 0.11, 95%CI 0.02-0.54), AMI (AMI vs normal; OR 0.11, 95%CI 0.02-0.54), AMSA (highest to lowest tertile; OR 15.5, 95%CI 1.7-140), and slope (highest to lowest tertile; OR 12.7, 95%CI 1.4-114). On multivariate regression, untreated VF duration (P=0.011) and AMI (P=0.003) predicted ROSC within 3min. Among secondary outcome variables, favorable neurological status at 24h was only predicted by VF duration (OR 0.22, 95% CI 0.05-0.92).</AbstractText>In this swine model of VF, untreated VF duration and AMI were independent predictors of ROSC following VF cardiac arrest. AMSA and slope predicted ROSC when VF duration or the presence of AMI were unknown. Importantly, the initial treatment of choice for short duration VF is defibrillation regardless of VF waveform.</AbstractText> |
6,241 | The first documented cardiac arrest rhythm in hospitalized patients with heart failure. | Patients with heart failure (HF) have abnormal cellular anatomy and myocardial mechanics that may impact the initial rhythm and subsequent outcomes in cardiac arrest (CA).</AbstractText>Patients with pre-existing HF are less likely to have ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT) as the first documented rhythm in CA and have poorer survival than patients without pre-existing HF.</AbstractText>Identify the first documented cardiac arrest rhythm (FDR) in hospitalized patients with and without a pre-existing history of HF.</AbstractText>We evaluated 60,389 consecutive, adult, index, pulseless CA events with documented initial rhythm in the National Registry of Cardiopulmonary Resuscitation. The primary endpoint was the FDR in patients with and without a history of pre-existing HF. Secondary endpoints were return of spontaneous circulation (ROSC), survival to discharge, and neurological outcome.</AbstractText>Thirty three percent of patients had a pre-existing diagnosis of HF. HF patients were more likely to have VF/pVT (25.9 vs. 23.2%) and less likely to have asystole (34.4 vs. 35.3%, p=<.0001) than non-HF. There was no difference in survival to discharge (18.3 vs. 18.2%, p=.66), or good neurological outcomes (82.2 vs. 83.2%, p=.23) between the groups. Women were less likely to have VF/pVT as the first documented rhythm in both HF and non-HF groups.</AbstractText>Hospitalized patients with HF are more likely than those without HF to have VF/pVT as the FDR in CA, however the clinical magnitude of this difference is small. Overall survival and neurological outcomes are no different than hospitalized arrest patients without HF.</AbstractText> |
6,242 | Chronic augmentation of the parasympathetic tone to the atrioventricular node: a nonthoracotomy neurostimulation technique for ventricular rate control during atrial fibrillation. | The right inferior ganglionated plexus (RIGP) selectively innervates the atrioventricular node. Temporary electrical stimulation of this plexus reduces the ventricular rate during atrial fibrillation (AF). We sought to assess the feasibility of chronic parasympathetic stimulation for ventricular rate control during AF with a nonthoracotomy intracardiac neurostimulation approach.</AbstractText>In 9 mongrel dogs, the small endocardial area inside the right atrium, which overlies the RIGP, was identified by 20 Hz stimulation over a guiding catheter with integrated electrodes. Once identified, an active-fixation lead was implanted. The lead was connected to a subcutaneous neurostimulator. An additional dual-chamber pacemaker was implanted for AF induction by rapid atrial pacing and ventricular rate monitoring. Continuous neurostimulation was delivered for 1-2 years to decrease the ventricular rate during AF to a range of 100-140 bpm. Implantation of a neurostimulation lead was achieved within 37 +/- 12 min. The latency of the negative dromotropic response after on/offset or modulation of neurostimulation was <1 s. Continuous neurostimulation was effective and well tolerated during a 1-2 year follow-up with a stimulation voltage <5 V. The neurostimulation effect displayed a chronaxie-rheobase behavior (chronaxie time of 0.07 +/- 0.02 ms for a 50% decrease of the ventricular rate during AF).</AbstractText>Chronic parasympathetic stimulation can be achieved via a cardiac neurostimulator. The approach is safe, effective, and well tolerated in the long term. The atrioventricular nodal selectivity and the opportunity to adjust the negative dromotropic effect within seconds may represent an advantage over pharmacological rate control.</AbstractText> |
6,243 | Vernakalant (RSD1235) in the management of atrial fibrillation: a review of pharmacological properties, clinical efficacy and safety. | Vernakalant (RSD1235) is a novel antiarrhythmic agent for conversion of rapid onset atrial fibrillation (AF). It is an atria-selective multichannel ion blocker (blocks I(Kur), I(Na), I(Ca, L), I(to) and I(Kr)), with a small effect on ventricular repolarization. In clinical Phase II and III studies, vernakalant was moderately (approximately 50%) effective in converting AF of short duration (< 7 days), and effective (approximately 70-80%) in converting AF of less than 72 h, but was not effective in converting long duration AF (>7 days) or atrial flutter. Vernakalant seems to have only a small proarrhythmic effect, with no reported cases of torsades de pointes in direct relation to vernakalant administration in Phase II and III studies. Overall, there are few reported serious adverse events. |
6,244 | In-hospital and long-term prognosis after myocardial infarction in patients with prior coronary artery bypass surgery; 19-year experience. | To present a 19-year experience of the prognosis of patients with acute myocardial infarction (AMI) and prior coronary artery bypass surgery (CABS), 748 patients with AMI after prior CABS (postbypass group) and a control group of 1080 patients with AMI, but without prior CABS, were analyzed. All indexes of infarct size were lower in the postbypass group. There was more ventricular fibrillation in the postbypass group. In-hospital mortality was similar (p = 0.3675). In the follow-up period, postbypass patients had more heart failure, recurrent CABS, reinfarction, and unstable angina than did control patients. Cumulative survival was better in the control group than in the postbypass group (p = 0.0403). Multiple logistic regression model showed that previous angina (p = 0.0005), diabetes (p = 0.0058), and age (p = 0.0102) were independent predictor factors for survival. Use of digitalis and diuretics, together with previous angina, also influenced survival (p = 0.0092), as well as male gender, older patients, and diabetes together (p = 0.0420). Patients with AMI after prior CABS had smaller infarct, but more reinfarction, reoperation, heart failure, and angina. Previous angina, diabetes, and age, independently, as well as use of digitalis and diuretics together with angina, and male gender, older patients, and diabetes together, influenced a worse survival rate in these patients. |
6,245 | Introducing a new entity: chemotherapy-induced arrhythmia. | The relationship between chemotherapy and arrhythmias has not been well established. We reviewed the existing literature to better understand this connection. We reviewed published reports on chemotherapy-induced arrhythmias in English using the PubMed/Medline and OVID databases from 1950 onwards as well as lateral references. Arrhythmias were reported as a side effect of many chemotherapeutic drugs. Anthracyclines are associated with atrial fibrillation (AF) at a rate of 2-10%, but rarely with ventricular tachycardia (VT)/fibrillation. Taxol and other antimicrotubular drugs are safe in terms of pro-arrhythmic side effects and do not cause any consistent rhythm abnormalities. Arrhythmias induced by 5-fluorouracil, including VT, are mostly ischaemic in origin and usually occur in the context of coronary spasm produced by this drug. Cisplatin-particularly with intrapericardial use-is associated with a very high rate of AF (12-32%). Melphalan is associated with AF in 7-12% of cases, but it does not appear to cause VT. Interleukin-2 is linked to frequent arrhythmia, mostly AF. We summarized the available data on chemotherapy-induced arrhythmia, particularly AF and VT. Studies with prospective data collection and thorough analyses are needed to establish a causal relationship between certain anticancer drugs and arrhythmia. |
6,246 | Isolated left ventricular noncompaction syndrome. | Isolated left ventricular noncompaction (ILVNC) is a rare congenital cardiomyopathy characterized by prominent trabeculae, deep intertrabecular recesses, and thickened myocardium with 2 distinct layers (compacted and noncompacted). Clinical characteristics, outcomes, and appropriate therapies remain poorly defined. Data were collected on patients diagnosed with ILVNC by echocardiographic criteria at the Mayo Clinic from 2001 through 2006. These data were entered prospectively into a clinical database and retrospectively analyzed. All-cause mortality, stroke, and development of atrial fibrillation (AF) were compared to community and nonischemic dilated cardiomyopathic (DC) controls. Implantable cardioverter-defibrillator (ICD) therapies were examined. Thirty patients with confirmed ILVNC were included in analyses (mean age at diagnosis 39 +/- 19.5 years, 60% men). Three patients with ILVNC died during follow-up (mean 2.5 +/- 1.2 years) compared to 5 DC and 1 community controls. No mortality difference was observed among these groups (p = 0.42 and 0.054, respectively). No ILVNC deaths were observed in patients with normal LV ejection fraction. New-onset AF was diagnosed in 2 patients with ILVNC, and none was observed in DC controls. Stroke occurred in 2 DC controls and none was observed in patients with ILVNC. ICDs were implanted in 11 patients with ILVNC. No appropriate therapies were identified during follow-up, but 2 patients underwent inappropriate therapies related to AF. In conclusion, mortality in patients with ILVNC is similar to that in DC patients. Deaths were observed only in patients with decreased LV ejection fraction, suggesting that ICD therapy may be reserved for this subgroup. New-onset AF may lead to inappropriate ICD discharges. |
6,247 | Amiodarone for the prevention of reperfusion ventricular fibrillation. | The purpose of this study was to evaluate the efficacy of prophylactic single-dose amiodarone administered through the pump circuit before releasing the aortic cross-clamp (ACC) in preventing the occurrence of reperfusion ventricular fibrillation (RVF).</AbstractText>A prospective, randomized double-blind, placebo-controlled efficacy study.</AbstractText>A tertiary level teaching hospital.</AbstractText>Seventeen patients received 150 mg of amiodarone in 10 mL of normal saline by way of the pump 3 minutes before releasing the ACC, and a control group of 17 patients received 10 mL of normal saline.</AbstractText>The primary outcome of the study was the incidence of ventricular fibrillation requiring defibrillation during the 30-minute period after myocardial reperfusion. A large decrease in RVF (65% to 18%) was observed in the amiodarone-treated group with the number needed to treat only 2.1.The myocardial performance in terms of cardiac output was better in the amiodarone group; this could be attributed to the lower incidence of RVF and subsequent direct current shock therapy.</AbstractText>The observations showed that single-dose prophylactic amiodarone administered through the pump circuit 3 minutes before ACC release was an effective therapy to reduce the incidence of post-ACC release ventricular arrhythmias.</AbstractText>Copyright (c) 2010 Elsevier Inc. All rights reserved.</CopyrightInformation> |
6,248 | Scn3b knockout mice exhibit abnormal sino-atrial and cardiac conduction properties. | In contrast to extensive reports on the roles of Na(v)1.5 alpha-subunits, there have been few studies associating the beta-subunits with cardiac arrhythmogenesis. We investigated the sino-atrial and conduction properties in the hearts of Scn3b(-/-) mice.</AbstractText>The following properties were compared in the hearts of wild-type (WT) and Scn3b(-/-) mice: (1) mRNA expression levels of Scn3b, Scn1b and Scn5a in atrial tissue. (2) Expression of the beta(3) protein in isolated cardiac myocytes. (3) Electrocardiographic recordings in intact anaesthetized preparations. (4) Bipolar electrogram recordings from the atria of spontaneously beating and electrically stimulated Langendorff-perfused hearts.</AbstractText>Scn3b mRNA was expressed in the atria of WT but not Scn3b(-/-) hearts. This was in contrast to similar expression levels of Scn1b and Scn5a mRNA. Immunofluorescence experiments confirmed that the beta(3) protein was expressed in WT and absent in Scn3b(-/-) cardiac myocytes. Lead I electrocardiograms from Scn3b(-/-) mice showed slower heart rates, longer P wave durations and prolonged PR intervals than WT hearts. Spontaneously beating Langendorff-perfused Scn3b(-/-) hearts demonstrated both abnormal atrial electrophysiological properties and evidence of partial or complete dissociation of atrial and ventricular activity. Atrial burst pacing protocols induced atrial tachycardia and fibrillation in all Scn3b(-/-) but hardly any WT hearts. Scn3b(-/-) hearts also demonstrated significantly longer sinus node recovery times than WT hearts.</AbstractText>These findings demonstrate, for the first time, that a deficiency in Scn3b results in significant atrial electrophysiological and intracardiac conduction abnormalities, complementing the changes in ventricular electrophysiology reported on an earlier occasion.</AbstractText> |
6,249 | Surgical outcomes and post-operative changes in patients with significant aortic stenosis and severe left ventricle dysfunction. | Little is known regarding long-term survival and changes in systolic function following surgery after the occurrence of a severe left ventricular (LV) dysfunction in patients with severe aortic stenosis. Inclusion criteria were an aortic valve area less than 1 cm(2) and an LV ejection fraction (EF) less than 35%. Between January 1990 and July 2007, 41 (male: 30) patients were identified. The pre-operative mean EF and mean aortic valve area were 26.7+/-6.1% and 0.54+/-0.2 cm(2), respectively. Concomitant coronary artery bypass surgery was performed in 8 patients (19.6%). Immediate post-operative echocardiogram showed to be much improved in LV EF (27.2+/-5.5 vs. 37.4+/-11.3, P<0.001), LV mass index (244.2+/-75.3 vs. 217.5+/-71.6, P=0.006), and diastolic LV internal diameter (62.5+/-9.3 vs. 55.8+/-9.6, P<0.001). Post-operative LV changes were mostly complete by 6 months, and were maintained thereafter. There was one in-hospital mortality (2.4%) and 12 late deaths including one patient diagnosed with malignancy in whom LV function was normal. Multivariate analysis showed pre-operative atrial fibrillation and NYHA FC IV to be significant risk factors for cardiac-related death. Aortic valve replacement in patients with significant aortic stenosis and severe LV dysfunction showed acceptable surgical outcomes. Moreover, LV function improved significantly in many patients. |
6,250 | Primary prevention of atrial fibrillation: does the atrial lead position influence the incidence of atrial arrhythmias in patients with sinus node dysfunction? Results from the PASTA Trial. | PASTA (pacing of the atria in sinus node disease) is a prospective and randomized trial, assessing the effect of different atrial lead positions on the atrial fibrillation (AF) incidence in patients with sinus node disease (SND).</AbstractText>The atrial lead position is randomized to: (a) free right atrial wall, (b) right atrial appendage (RAA), (c) coronary sinus ostium (CS-Os), or (d) dual site right atrial pacing (CS-Os + RAA). The pacemakers (Vitatron Selection 9000 or Prevent AF, Vitatron B.V., Arnhem, The Netherlands) are programmed in DDDR 70 mode and the total follow-up duration is 24 months. To describe the atrial rhythm state, pacemaker-derived data (arrhythmia counter) were assessed for AF episodes. AF was considered as evident, if the AF burden (time in AF related to follow-up interval) was >1% (i.e., 15 min/d). Follow-up data after 24 months were evaluated.</AbstractText>The analysis evaluates 142 patients (77 male, 74.5 +/- 7.8 years). There was no statistical significant difference with respect to the occurrence of AF between the four groups after 24 months (A: 36%; B: 38%, C: 32%, D: 48%). The percentage of atrial/ventricular pacing was in A: 78/76%, in B: 84/81%, in C: 70/65%, and in D: 79/69%. These differences were not significant.</AbstractText>The evaluation of the AF burden >1% and the total AF burden after 24 months did not show differences in the incidence of AF in patients with dual chamber pacemaker therapy for SND. We were not able to demonstrate a significant influence of right atrial lead position on the incidence of AF recurrence.</AbstractText> |
6,251 | Model-based control of cardiac alternans on a ring. | Cardiac alternans, a beat-to-beat alternation of cardiac electrical dynamics, and ventricular tachycardia, generally associated with a spiral wave of electrical activity, have been identified as frequent precursors of the life-threatening spatiotemporally chaotic electrical state of ventricular fibrillation (VF). Schemes for the elimination of alternans and the stabilization of spiral waves through the injection of weak external currents have been proposed as methods to prevent VF but have not performed at the level required for clinical implementation. In this paper we propose a control method based on linear-quadratic regulator (LQR) control. Unlike most previously proposed approaches, our method incorporates information from the underlying model to increase efficiency. We use a one-dimensional ringlike geometry, with a single control electrode, to compare the performance of our method with that of two other approaches, quasi-instantaneous suppression of unstable modes (QISUM) and time-delay autosynchronization (TDAS). We find that QISUM fails to suppress alternans due to conduction block. Although both TDAS and LQR succeed in suppressing alternans, LQR is able to suppress the alternans faster and using a much weaker control current. Our results highlight the benefits of a model-based control approach despite its inherent complexity compared with nonmodel-based control such as TDAS. |
6,252 | [Atrial fibrillation in hypertrophic cardiomyopathy: determinants, clinical course and management]. | Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with hypertrophic cardiomyopathy (HCM), and represents an important complication in the clinical course of the disease, with adverse consequences on functional status and outcome. Studies on community-based HCM patient populations have shown that AF is associated with long-term clinical deterioration, cardioembolic stroke and increased cardiovascular mortality due to heart failure and stroke. Moreover, acute onset of AF may cause severe hemodynamic impairment and represent a trigger of potentially lethal ventricular arrhythmias. However, the consequences of AF on the long-term prognosis of HCM patients are not uniformly unfavorable, and may be compatible with an uneventful course, when properly managed. Management of AF in HCM is challenging, particularly when onset occurs at a young age. Both paroxysmal and permanent AF represent clear indications for oral anticoagulation. In most patients, maintenance of sinus rhythm is highly desirable but made difficult by the limited long-term efficacy and potentially hazardous side effects of available pharmacological options. In selected patients with HCM and severely symptomatic AF, radiofrequency catheter ablation may represent an effective therapeutic alternative, improving functional status, and reducing or postponing the need for antiarrhythmic drugs. In patients with persistent AF, in whom maintenance of sinus rhythm is not feasible, adequate ventricular rate control should be pursued aggressively by atrio-ventricular node blocking agents. |
6,253 | [Prevention of sudden death in hypertrophic cardiomyopathy (HCM ): implanted defibrillators in HCM]. | Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people. The implantable cardioverter-defibrillator (ICD), has recently proved to be a safe and effective therapeutic intervention in patients with HCM, both for the primary and secondary prevention of sudden death. Based on recent substantial experience, the ICD intervenes appropriately to terminate ventricular tachycardia/fibrillation (VT/VF), at a rate of 5.5%/year. ICD discharge rate is 4%/year in those patients implanted prophylactically due to one or more major risk markers, but often with considerable delays of up to 10 years before the device is required to intervene appropriately to terminate potentially letal ventricular tachyarrhythmias. Primary prevention of VT/VF occurs with similar frequency in high-risk patients having either 1, 2 or > or =3 noninvasive risk markers, and about one-third of patients with appropriate device interventions had been implanted for only one risk factor. The ICD has proved reliable in HCM despite the extreme and complex phenotypes often present with massive degrees of left ventricular hypertrophy, microvascular ischemia, diastolic dysfunction, or dynamic left ventricular outflow tract obstruction. Failure to convert life-threatening ventricular tachyarrhythmias to normal rhythm is extraordinarily rare. In conclusion, in high-risk HCM patients, ICDs perform in a highly effective fashion, frequently preventing sudden death by aborting primary life-threatening ventricular tachyarrhythmias. A single marker of high risk can be sufficient evidence to justify the recommendation for a prophylactic ICD in selected patients with HCM. |
6,254 | No assisted ventilation cardiopulmonary resuscitation and 24-hour neurological outcomes in a porcine model of cardiac arrest. | To evaluate the effect of no assisted ventilation cardiopulmonary resuscitation on neurologically intact survival compared with ten positive pressure ventilations/minute cardiopulmonary resuscitation in a pig model of cardiac arrest.</AbstractText>Prospective randomized animal study.</AbstractText>Animal laboratory.</AbstractText>Sixteen female intubated pigs (25.2 +/- 2.1 kg) anesthetized with propofol.</AbstractText>: fter 8 mins of untreated ventricular fibrillation, the intubated animals were randomized to 8 mins of continuous chest compressions (100/min) and either no assisted ventilation (n = 9) or 10 positive pressure ventilations/min (Smart Resuscitator Bag with 100% O2 flow at 10 L/min) (n = 7). The primary end point, neurologically intact 24-hr survival, was evaluated using a pig cerebral performance category score by a veterinarian blinded to the cardiopulmonary resuscitation method. MEASUREMENTS, AND MAIN RESULTS: During cardiopulmonary resuscitation, aortic and coronary perfusion pressure were similar between groups but cerebral perfusion pressure was significantly higher in the positive pressure ventilation group (33 +/- 15 vs. 14 +/- 14, p = .04). After 7.5 mins of cardiopulmonary resuscitation, arterial pO2 (mm Hg) and mixed venous O2 saturation (%) were significantly higher in the positive pressure ventilation compared with the no assisted ventilation group (117 +/- 29 and 41 +/- 21 vs. 40 +/- 24 and 10.8 +/- 7; p = .01 for both). Paco2 was significantly lower in the positive pressure ventilation group (48 +/- 10 vs. 77 +/- 26, p = .01). After 24 hrs, four of nine no assisted ventilation pigs were alive with a mean cerebral performance category score of 3 +/- 0 vs. five of seven alive and neurologically intact positive pressure ventilation pigs with a cerebral performance category score of 1 +/- 0.3 (p < .001 for cerebral performance category score).</AbstractText>No assisted ventilation cardiopulmonary resuscitation results in profound hypoxemia, respiratory acidosis, and significantly worse 24-hr neurologic outcomes compared with positive pressure ventilation cardiopulmonary resuscitation in pigs.</AbstractText> |
6,255 | Therapeutic hypothermia (30 degrees C) enhances arrhythmogenic substrates, including spatially discordant alternans, and facilitates pacing-induced ventricular fibrillation in isolated rabbit hearts. | Therapeutic hypothermia (TH, 30 degrees C) protects the brain from hypoxic injury. However, TH may potentiate the occurrence of lethal ventricular fibrillation (VF), although the mechanism remains unclear. The present study explored the hypothesis that TH enhances wavebreaks during VF and S(1) pacing, facilitates pacing-induced spatially discordant alternans (SDA), and increases the vulnerability of pacing-induced VF.</AbstractText>Using an optical mapping system, epicardial activations of VF were studied in 7 Langendorff-perfused isolated rabbit hearts at baseline (37 degrees C), TH (30 degrees C), and rewarming (37 degrees C). Action potential duration (APD)/conduction velocity (CV) restitution and APD alternans (n=6 hearts) were determined by S(1) pacing at these 3 stages. During TH, there was a higher percentage of VF duration containing epicardial repetitive activities (spatiotemporal periodicity) (P<0.001). However, TH increased phase singularity number (wavebreaks) during VF (P<0.05) and S(1) pacing (P<0.05). TH resulted in earlier onset of APD alternans (P<0.001), which was predominantly SDA (P<0.05), and increased pacing-induced VF episodes (P<0.05). TH also decreased CV, shortened wavelength, and enhanced APD dispersion and the spatial heterogeneity of CV restitution.</AbstractText>TH (30 degrees C) increased the vulnerability of pacing-induced VF by (1)facilitating wavebreaks during VF and S(1) pacing, and (2)enhancing proarrhythmic electrophysiological parameters, including promoting earlier onset of APD alternans (predominantly SDA) during S(1) pacing.</AbstractText> |
6,256 | Brain natriuretic peptide for the prediction of sudden cardiac death and ventricular arrhythmias: a meta-analysis. | The risk stratification of patients for sudden cardiac death (SCD) remains a challenge. Brain natriuretic peptide (BNP) predicts overall mortality in heart disease but it is unclear how well it predicts SCD. We therefore performed a meta-analysis of studies evaluating the accuracy of BNP to predict SCD and ventricular arrhythmias (VA).</AbstractText>Electronic databases and published bibliographies were systematically searched (1984-2008). We found 14 studies that met our inclusion criteria. Six studies (3543 patients) evaluated BNP to predict SCD in patients without implantable cardioverter defibrillators (ICDs) across a wide range of populations. A raised BNP predicted SCD with a relative risk of 3.68 [95% confidence interval (CI) 1.90, 7.14]. Eight studies (1047 patients) evaluated BNP to predict the occurrence of VA in patients with ICDs. A raised BNP predicted the occurrence of VA with a relative risk of 2.54 (95% CI 1.87, 3.44).</AbstractText>The measurement of BNP has significant value in predicting SCD and VA. However, the benefit of BNP testing in addition to other risk stratification tests is unclear and BNP needs to be evaluated prospectively in combination with other complementary risk stratification tools.</AbstractText> |
6,257 | [Mild therapeutic hypothermia following resuscitation; experience and results in the first two years after introduction]. | To describe the results of mild therapeutic hypothermia (MTH) following resuscitation in the 'Gelderse Vallei' hospital, Ede, the Netherlands.</AbstractText>Descriptive, retrospective.</AbstractText>Patient data was collected from patients who had undergone MTH during the first two years following introduction of this treatment in the intensive care department of the 'Gelderse Vallei' hospital, Ede. Information used in the description included patient characteristics, heart arrest type (ventricular fibrillation or other arrhythmias), place of onset (in hospital or elsewhere), resuscitation data, side effects of the treatment, mortality and neurological outcome.</AbstractText>67 patients were treated with MTH in the period April 2005 to July 2007. The hospital mortality rate within this group was 81%. The mortality rate in the subgroup presenting with ventricular fibrillation as initial arrhythmia was 76%, compared with 89% in the subgroup with other arrhythmias. The mortality rate of patients who were resuscitated outside the hospital was comparable with that for patients resuscitated in hospital (80% versus 83%). Patients who could be discharged from hospital had a good neurological outcome (average Cerebral Performance Category score 1.9; 95%-CI: 1.6-2.2). The most important complications during MTH were electrolyte imbalances and ventilator associated pneumonia.</AbstractText>The introduction of MTH in the intensive care department of the "Gelderse Vallei" has taken place without major problems. Although the mortality rate following cardiopulmonary resuscitation was relatively high, the neurological outcome in those patients who were discharged from hospital alive was good.</AbstractText> |
6,258 | [How to improve response to cardiac resynchronization therapy?]. | Cardiac resynchronization therapy decreases mortality and rehospitalization for heart failure. However, around 30% of patients do not respond to this therapy. The paper analyses factors, with a possible impact on the response to this therapy. It is a left ventricular lead proximity to the left ventricle segment with the latest activity, presence and size of postinfarction scar and a percentage of fully captured paced beats. Methods of optimalization of these factors are described as well as circumstances, under which some patients should be indicated for cardiosurgical lead implantation or if a cardiac resynchronization therapy should be ommited. |
6,259 | Late gadolinium enhancement in cardiovascular magnetic resonance in patients with hypertrophic cardiomyopathy complicated by life-threatening ventricular tachyarrhythmia. | Late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) has been shown to be associated with ventricular arrhythmias, however, its prognostic role in predicting sudden cardiac death has not yet been established.</AbstractText>To explore a potential relationship between LGE visualised by CMR and life-threatening ventricular tachyarrhythmia in hypertrophic cardiomyopathy (HCM).</AbstractText>The LGE in CMR was assessed in 55 HCM patients. We compared the frequency and extent of LGE in HCM patients with sustained ventricular tachycardia (VT) or who survived ventricular fibrillation (VF) or sudden death [group VF (+)] versus HCM patients without these tachyarrhythmias [group VF (-)]. There were 14 patients in the VF (+) group and 41 patients in the VF (-) group, and they were followed for a mean period of 37 months.</AbstractText>In group VF (+), adequate ICD intervention occurred in 9 patients (8 patients with VF and one patient with sustained VT), and VF arrest occurred in 5 patients (4 patients were resuscitated and one patient had a witnessed sudden death). In group VF (+) all patients had LGE whereas in group VF (-) 85% patients presented this abnormality (p = 0.13). Moreover, there were no statistical differences between groups in the following parameters: age, total left ventricular (LV) mass, maximal LV wall thickness, mass of hyperenhanced myocardium and percent of hyperenhanced myocardium.</AbstractText>In HCM patients with life-threatening ventricular tachyarrhythmia LGE was both qualitatively and quantitatively comparable with patients without these tachyarrhythmias.</AbstractText> |
6,260 | [Life-threatening ventricular arrhythmia during simultaneous administration of propafenone and sotatol]. | A case of a patient treated with antiarrhythmic drugs for ventricular arrhythmia occurring after viral infection of the respiratory tract is presented. In the course of preliminary cardiologic examination no organic heart disease was diagnosed. Due to numerous ventricular extrasystolic beats (16,500 per day) and short runs of non-sustained ventricular tachycardia (maximum of 4 subsequent beats) propafenone was introduced. Persistent arrhythmia was a reason for adding sotalol to that treatment in an outpatient clinic. After three weeks of such treatment the patient presented cardiac arrest in the mechanism of ventricular tachycardia and fibrillation. Successful resuscitation and drug discontinuation led to complete resolution of the life-threatening arrhythmia. No inducible complex ventricular arrhythmia was observed during electrophysiologic examination. |
6,261 | Recurrence of ventricular arrhythmias in patients with non-ischaemic dilated cardiomyopathy: evidence-based predictors. | Ventricular arrhythmia (VA) is the most frequent cause of sudden death among patients with non-ischaemic dilated cardiomyopathy (DCM).</AbstractText>To identify the important VA risk factors in patients with DCM.</AbstractText>Eighty-five DCM patients (73 males, mean age 54 years) with DCM and implantable cardioverter defibrillators (ICD) were followed for 21+/-19 months after ICD implantation. The mean follow-up was 21 months. Data from 55 patients with VA recorded in the ICD memory and requiring ICD intervention during follow-up were compared with 30 patients without arrhythmia. Cox regression analysis identified the following univariate predictors of VA: alcoholic aetiology of DCM (0.05), diuretic treatment (0.003), history of cardiac arrest (0.03), right ventricular diastolic diameter (0.001). Both ACE inhibitor (ACEI) and statin treatments were associated with a tendency towards decreased risk of VA. Multivariate logistic analysis identified four predictors as significantly related to VA: alcoholic aetiology (HR 4.8, p=0.008), ACEI treatment (HR 0.4, p=0.01), diuretic treatment (HR 2.6, p=0.015), and statin treatment (HR 0.1, p=0.03).</AbstractText>The majority of patients with DCM and ICD have recurrences of VA. Alcoholic aetiology of DCM is associated with an increase in the incidence of arrhythmias. Treatment with ACEI and statins is associated with a reduction of arrhythmias.</AbstractText> |
6,262 | Graft fixation with a side graft holder for sequential and composite graft anastomosis in coronary artery bypass surgery. | The purpose of this study was to assess the feasibility and effectiveness of graft fixation with a novel side graft holder for sequential or composite graft anastomosis in coronary artery bypass grafting (CABG). Records of 34 patients who underwent CABG using sequential or composite graft anastomosis technique were reviewed. The device was used on 47 anastomoses (sequential=43; composite graft=4). Excellent fixation and visualization of the graft was obtained in all patients without graft injury. Postoperative angiographic patency rate of distal anastomoses was 95.2% (arterial, 91.2%; venous, 96.7%). All sequential and composite graft anastomoses were patent and without stenosis. One operative death occurred due to low cardiac output after emergent CABG for acute myocardial infarction. No elective patient died during hospitalization. Postoperative complications occurred in two patients (ventricular fibrillation, 1; postoperative catheter intervention, 1). No perioperative myocardial infarctions or re-operations occurred. Our clinical experience shows that graft fixation with the device is safe, reliable, and effective for sequential and composite graft anastomosis during CABG. |
6,263 | Case of transient mid-ventricular ballooning syndrome with a rapid and uncommon recovery. | A 60-year-old woman presented with acute pulmonary edema followed by cardiopulmonary arrest due to idiopathic ventricular fibrillation. Owing to immediate cardioversion, her electrocardiogram showed sinus rhythm and echocardiography did not show any wall motion abnormalities. The next day, echocardiographic re-examination was characterized by akinesis of both apical and mid segments of the left ventricle. One hour later, subsequently performed coronary angiography revealed non-occlusive coronary artery disease, but left ventriculography demonstrated only akinesis of mid-ventricular segment with hypercontractile other segments. Further echocardiographic investigation on the following day showed total resolution of left ventricular wall motion abnormalities. The diagnosis of mid-ventricular ballooning syndrome was made according to the findings of left ventriculography. In this case, the time course changes of both patient's pathophysiological condition and echocardiographic wall motion from the onset to recovery are rapid and uncommon. |
6,264 | Repair of left ventricular aneurysm: ten-year experience in Chinese patients. | A large transmural myocardial infarction often results in a dyskinetic or akinetic left ventricular aneurysm (LVA). This study aimed to explore the early and long-term clinical outcomes and to identify predictors for survivals and hospital re-admission after the repair of left ventricular aneurysm.</AbstractText>We followed up 497 patients who had undergone LVA repair from a single center in China between 1995 and 2005. The perioperative parameters were recorded. Risk factors for early mortality and long-term results were analyzed by multivariate Logistic regression. Cox's proportional hazard model was used to calculate risk factors for major adverse cardiac and cerebrovascular events, cause of death and re-admission. Kaplan-Meier curve was employed to analyze long-term survival.</AbstractText>The operative mortality was 2.0%. The long-term mortality was 11.1% and cardiac causes contributed to 61.8% of the overall long-term mortality. Four hundred and thirty-two patients survived during the follow-up period and 37.5% of them had been re-admitted at least one time. One hundred and five patients experienced major adverse cardiac and cerebrovascular events. Survival analysis exhibited that the probability of survival at 1 and 5 years after operation was 96% and 86% respectively. Previous atrial fibrillation was the independent risk factor for early mortality. Independent risk factors for long-term mortality were poor left ventricular ejection fraction and stroke,and risk factors for cardiac mortality were intraventricular block, stroke and poor left ventricular ejection fraction. Stroke, intraventricular block and advanced age were independent risk factors for major adverse cardiac and cerebrovascular events, and New York Heart Association (NYHA) class III-IV was the only risk factor for hospital re-admission.</AbstractText>Postinfarction LVA can be repaired and satisfying early and long-term clinical outcome can be obtained. Endoventricular circular plasty technique is the better choice than linear repair in patients with large LVA. Survival is affected in patients with poor heart function, intraventricular block and stroke.</AbstractText> |
6,265 | [Clinical characteristics and treatment of a Chinese family with congenital short QT syndrome.]. | To observe the clinical characteristics and therapeutic efficacy of a Chinese family with congenital short QT Syndrome (SQTs).</AbstractText>Fourteen family members including the proband were screened with routine clinical examination, serum electrolyte, serum myocardial enzymes, electrocardiography (ECG), Holter recording, treadmill exercise test, echocardiography and chest radiograph. High risk patient received intracardiac electrophysiological study (EPS).</AbstractText>Among the fourteen family members, 4 members died of sudden cardiac death at young ages, 4 members including the proband and his two daughters and one son were diagnosed as SQTs with structurally intact hearts. Initial ECG in these subjects revealed sinus rhythm with a high peaked T wave, QTc interval </= 320 ms and QT/QTp < 80%. The proband was a 45-year-old man presented with occasional dizziness and family history of sudden cardiac death. Polymorphic ventricular tachyarrhythmias and ventricular fibrillation as well as syncope were induced in this patient during programmed stimulation (S1 = 400 ms, S2 = 250 ms, S3 = 140 ms) from right ventricular outflow tract and a dual chamber Implantable Cardioverter Defibrillator (ICD) was implanted and the patient remained asymptomatic during the 6 months follow up.</AbstractText>SQTs could be presented as an inherited disorder with increased risk for arrhythmias and sudden cardiac death. ICD implantation is the first-choice therapy for high risk patients.</AbstractText> |
6,266 | [Brugada syndrome--a brand new case]. | Brugada syndrome (BS) is a disorder characterized by syncope or sudden death associated with one of several electrocardiographic (ECG) patterns characterized by incomplete right bundle branch block and ST elevation in the anterior precordial leads. Patients with BS are prone to develop ventricular tachyarrhythmias that may lead to syncope, cardiac arrest, or sudden cardiac death.</AbstractText>A 58-year-old woman is the first described case of Brugada syndrome in Serbia with intermittent typical changes in basic electrocardiography (ECG): ST segment elevation in the precordial chest leads like dome or coved--major form or type I. For the last 27 years the patient had suffered of palpitations and dizziness, without syncopal events. Her sister had died suddenly during the night in sleep. During 24-hour Holter monitoring the patient had ventricular premature beats during the night with R/T phenomenon and during the recovery phase of exercise testing had rare premature ventricular beats as the consequence of parasympatethic stimulation. Late potentials were positive. Echocardiography revealed left ventricular ejection fraction of 60%. We performed coronary angiography and epicardial coronary arteries were without significant stenosis and structural heart disease was excluded. In the bigining of the electrophysiological study ECG was normal, and after administration of Propaphenon i.v. Brugada syndrome unmasked with appearance of type I ECG pattern. A programed ventricular stimulation induced non sustained ventricular tachycardia. One-chamber implantable cardioverter defibrillator was implanted and the patient was treated with a combination od amiodarone and metoprolol per os. After one-year folow-up, there were no episodes of ventricular tachycardia and ventricular fibrillation.</AbstractText>Brugada syndrome is a myocardial disorder which prognosis and therapy are related to presence of ventricular fibrillation or ventricular tachycardia. Electrophysiologicaly induced malignant ventricular disorders class I are indication for implantation of cardioverter defibrilator, as also occurred in presented patient.</AbstractText> |
6,267 | [Clinical and prognostic significance of left bundle branch block in patients with severe chronic heart failure]. | Clinical and prognostic significance of left bundle branch block (LBBB) was investigated in 62 elderly patients with severe chronic heart failure (CHF). In comparison to 93 patients with CHF but without intra-ventricular blocks patients with LBBB demonstrated more frequently atrial fibrillation and left ventricular systolic dysfunction but less frequently chronic obstructive pulmonary disease, anemia and a history of myocardial infarction. Fourth-year follow-up showed that LBBB was not important predictor of survival in patients with severe CHF. |
6,268 | Rate of progression and functional significance of aortic root calcification after homograft versus freestyle aortic root replacement. | Calcification is an important limitation after aortic root replacement. The aims were to compare the long-term degree and rate of calcification of homografts versus Medtronic freestyle aortic roots to determine the functional consequences and predictive factors.</AbstractText>One hundred sixty-six patients were prospectively randomized to undergo homograft versus freestyle total aortic root replacement. Of those, 98 patients underwent a total of 248 electron beam computed tomography studies at 0.5, 1, 1.5, 2, 3, and 8 years. All patients underwent yearly clinical and echocardiographic follow-up. Calcium scores were measured using Agatston scoring. Mixed effects models demonstrate significantly higher calcium scores in homograft roots than freestyle at 1.5 years (P=0.02), 2 years (P=0.02), and 3 years (P=0.01), with a trend at 1 year (P=0.06) and 8 years (P=0.1). Homograft calcification occurs significantly faster than in freestyle prostheses between 6 months and 3 years after surgery (P=0.02). Calcification occurs at a similar rate thereafter up to 8 years (P=0.3). At 8 years, freedom from aortic valve dysfunction was lower in homografts than freestyle roots (P=0.06). Freedom from reoperation was 93+/-4% in the homograft group versus 100+/-0% in the freestyle group at 8 years (P=0.01). On multivariate analysis, redo surgery (P<0.001), smoking (P<0.01), atrial fibrillation (P=0.001), family history of coronary artery disease (P<0.01), and a degenerative etiology (P=0.02) were predictive of higher calcium scores.</AbstractText>Homograft roots exhibit significantly higher calcium scores than freestyle roots because of faster early calcification.</AbstractText> |
6,269 | Effect of hypercholesterolemia on myocardial necrosis and apoptosis in the setting of ischemia-reperfusion. | Hypercholesterolemia is prevalent in patients who experience myocardial ischemia-reperfusion injury (IR). We investigate the impact of dietary-induced hypercholesterolemia on the myocardium in the setting of acute IR.</AbstractText>In normocholesterolemic (NC, n=7) and hypercholesterolemic (HC, n=7) Yucatan male pigs, the left anterior descending coronary artery was occluded for 60 minutes, followed by reperfusion for 120 minutes. Hemodynamic values were recorded, and TTC staining was used to assess necrosis. Oxidative stress was measured. Specific cell death and survival signaling pathways were assessed by Western blot and TUNEL staining. Infarct size was 45% greater in HC versus NC (42% versus 61%, P<0.05), whereas the area at risk (AAR) was similar in both groups (P=0.61). Whereas global LV function (+dP/dt, P<0.05) was higher during entire period of IR in HC versus NC, regional function deteriorated more following reperfusion in HC (P<0.05). Ischemia increased indices of myocardial oxidative stress such as protein oxidation (P<0.05), lipid peroxidation (P<0.05), and nitrotyrosylation in HC versus NC, as well as the expression of phospho-eNOS (P<0.05). The expression of myeloperoxidase, p38 MAPK, and phospho-p38 MAPK was higher in HC versus NC (all P<05). Ischemia caused higher expression of the proapoptotic protein PARP (P<0.05), and lower expression of the prosurvival proteins Bcl2 (P<0.05), phospho-Akt, (P<0.05), and phospho-PKCepsilon (P<0.05) in the HC versus NC. TUNEL-positive cell count was 3.8-fold (P<0.05) higher in the AAR of HC versus NC.</AbstractText>This study demonstrates that experimental hypercholesterolemia is associated with increased myocardial oxidative stress and inflammation, attenuation of cell survival pathways, and induction of apoptosis in the ischemic territory, which together may account for the expansion of myocardial necrosis in the setting of acute IR.</AbstractText> |
6,270 | Organ donation after cardiac determination of death (DCD): a swine model. | Donors after Cardiac Death (DCD) may reduce the organ scarcity; however, their use is limited because of warm ischemia time. Fortunately, this is less important in a subclass of DCD called expected (e-DCD), those with irreversible but incomplete brain injury. This study analyzed hemodynamic/pulmonary data to establish a clinically relevant model of cardiac death that would simulate an e-DCD setting. Hemodynamics, pulmonary artery flows, arterial blood gasses, and left atrial pressure were recorded q 5 minutes in anesthetized swine. After baseline data collection, the ventilator was discontinued and heparin was administered. Cardiac death was defined: as asystole, or mean arterial presusure < or = 25 mm Hg with a pulse pressure < or = 20 mm Hg. The time to death was approximately 14.8 minutes. Within 5 minutes of removal of the ventilator, there was a hyperdynamic period. Blood gases throughout the apneic time showed a rapid hypercapnia and acidosis. The hyperdynamic reflex response was followed by hypotension, bradycardia, and finally asystole or ventricular fibrillation. The protocol of withdrawal of ventilation, systemic anticoagulation, determination of death was developed to closely resemble the clinical e-DCD scenario. The physiologic changes that happen before death in DCD were described. An e-DCD model that can be used in studies related to organ transplantation was established. |
6,271 | Rhythms and outcomes of adult in-hospital cardiac arrest. | To determine the relationship of electrocardiographic rhythm during cardiac arrest with survival outcomes.</AbstractText>Prospective, observational study.</AbstractText>Total of 411 hospitals in the National Registry of Cardiopulmonary Resuscitation.</AbstractText>Total of 51,919 adult patients with pulseless cardiac arrests from April 1999 to July 2005.</AbstractText>Registry data collected included first documented rhythm, patient demographics, pre-event data, event data, and survival and neurologic outcome data. Of 51,919 indexed cardiac arrests, first documented pulseless rhythm was ventricular tachycardia (VT) in 3810 (7%), ventricular fibrillation (VF) in 8718 (17%), pulseless electrical activity (PEA) in 19,262 (37%) and asystole 20,129 (39%). Subsequent VT/VF (that is, VT or VF occurring during resuscitation for PEA or asystole) occurred in 5154 (27%), with first documented rhythm of PEA and 4988 (25%) with asystole. Survival to hospital discharge rate was not different between those with first documented VF and VT (37% each, adjusted odds ratio [OR]) 1.08; 95% confidence interval [CI] 0.95-1.23). Survival to hospital discharge was slightly more likely after PEA than asystole (12% vs. 11%, adjusted OR 1.1; 95% CI 1.00-1.18), Survival to discharge was substantially more likely after first documented VT/VF than PEA/asystole (adjusted OR 1.68; 95% CI 1.55-1.82). Survival to discharge was also more likely after PEA/asystole without subsequent VT/VF compared with PEA/asystole with subsequent VT/VF (14% vs. 7% for PEA without vs. with subsequent VT/VF; 12% vs. 8% for asystole without vs. with subsequent VT/VF; adjusted OR 1.60; 95% CI, 1.44-1.80).</AbstractText>Survival to hospital discharge was substantially more likely when the first documented rhythm was shockable rather than nonshockable, and slightly more likely after PEA than asystole. Survival to hospital discharge was less likely following PEA/asystole with subsequent VT/VF compared to PEA/asystole without subsequent VT/VF.</AbstractText> |
6,272 | Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: a retrospective before-and-after comparison in a single hospital. | To evaluate whether implementation of a therapeutic hypothermia protocol on arrival in a community hospital improved survival and neurologic outcomes in patients initially found to have ventricular fibrillation, pulseless electrical activity, or asystole, and then successfully resuscitated from out-of-hospital cardiac arrest.</AbstractText>A retrospective study of patients who presented after implementation of a therapeutic hypothermia protocol compared with those who presented before the protocol was implemented.</AbstractText>Harborview Medical Center, Seattle, WA.</AbstractText>A total of 491 consecutive adults with out-of-hospital, nontraumatic cardiac arrest who presented between January 1, 2000 and December 31, 2004.</AbstractText>An active cooling therapeutic hypothermia protocol, using ice packs, cooling blankets, or cooling pads to achieve a temperature of 32 degrees C to 34 degrees C was initiated on November 18, 2002 for unconscious patients resuscitated from cardiac arrest.</AbstractText>Demographics and outcomes were obtained from medical records and an emergency medical database. The primary outcomes were survival and favorable neurologic outcome at discharge associated with the therapeutic hypothermia protocol. An adjusted analysis was performed, using a multivariate regression. During the therapeutic hypothermia period, 204 patients were brought to the emergency department; of these 204 patients, 132 (65%) ultimately achieved temperatures of <34 degrees C. Of the 72 patients who did not achieve goal temperatures: 40 (20%) died in the emergency department or shortly after being admitted to the hospital, 15 (7%) regained consciousness, four (2%) had contraindications, 13 (6%) had temperature increase or did not have documented use of the therapeutic hypothermia protocol. In the prior period, none of the 287 patients received active cooling. Patients admitted in the therapeutic hypothermia period had a mean esophageal temperature of 34.1 degrees C during the first 12 hrs compared with 35.2 degrees C in the pretherapeutic hypothermia period (p < .01). Survival to hospital discharge improved in the therapeutic hypothermia period in patients with an initial rhythm of ventricular fibrillation (odds ratio, 1.88, 95% confidence interval, 1.03-3.45), however not in patients with nonventricular fibrillation (odds ratio, 1.17, 95% confidence interval, 0.66-2.05). In adjusted analysis, ventricular fibrillation patients during the therapeutic hypothermia period trended toward improved survival (odds ratio, 1.71, 95% confidence interval, 0.85-3.46) and had favorable neurologic outcome (odds ratio, 2.62, 95% confidence interval, 1.1-6.27) compared with the earlier period. This benefit was not observed in patients whose initial rhythm was pulseless electrical activity or asystole.</AbstractText>The therapeutic hypothermia period was associated with a significant improvement in neurologic outcomes in patients whose initial rhythm was ventricular fibrillation, but not in patients with other rhythms.</AbstractText> |
6,273 | Assessment of CPR-D skills of nursing students in two institutions: reality versus recommendations in the guidelines. | Significant differences in basic life support skills including cardiopulmonary resuscitation and defibrillation (CPR-D) were detected when nurses working in one Finnish and one Swedish hospital were tested using an Objective Structured Clinical Examination (OSCE). The purpose of this study was to use OSCE test in assessing guideline based CPR-D skills of newly qualified nurses. The CPR-D skills of newly qualified registered nurses studying in Halmstad University (n = 30), Sweden, Helsinki Metropolia University of Applied Sciences (n = 30), and Finland were assessed using an OSCE which was built up with a case of cardiac arrest with ventricular fibrillation as the initial rhythm. The Angoff average, 32.47, was calculated as cutoff point to pass the test. Forty-seven percent of the students in the Swedish group (mean score 32.47/49, range 26-39, SD 3.76) and 13% of the students in the Finnish group (mean score 23.80/49, range 13-35, SD 4.32) passed the OSCE (P<0.0001), the cutoff point being 32.47. Performance grade for the Swedish group was 2.9/5.0 and for the Finnish group 2.1/5.0 (P<0.0001). Good nontechnical skills correlated with high grading of the clinical skills. In conclusion, CPR-D skills of the newly qualified nurses in both the institutes were clearly under par and were not adequate according to the resuscitation guidelines. Current style of teaching is unlikely to result in students being able to perform adequate CPR-D. Standardized testing would help in controlling the quality of learning. |
6,274 | Neuronal nitric oxide synthase protects against myocardial infarction-induced ventricular arrhythmia and mortality in mice. | Neuronal nitric oxide synthase (nNOS) is expressed in cardiomyocytes and plays a role in regulating cardiac function and Ca2+ homeostasis. However, the role of nNOS in cardiac electrophysiology after myocardial infarction (MI) is unclear. We hypothesized that nNOS deficiency increases ventricular arrhythmia and mortality after MI.</AbstractText>MI was induced in wild-type (WT) or nNOS(-/-) mice by ligation of the left coronary artery. Thirty-day mortality was significantly higher in nNOS(-/-) compared with WT mice. Additionally, nNOS(-/-) mice had impaired cardiac function 2 days after MI. Telemetric ECG monitoring showed that compared with WT, nNOS(-/-) mice had significantly more ventricular arrhythmias and were more likely to develop ventricular fibrillation after MI. Treatment with the L-type Ca2+ channel blocker verapamil reduced the incidence of arrhythmia and ventricular fibrillation in nNOS(-/-) mice after MI. To assess the role of nNOS in Ca2+ handling, patch-clamp and Ca2+ fluorescence techniques were used. Ca2+ transients and L-type Ca2+ currents were higher in nNOS(-/-) compared with WT cardiomyocytes. Additionally, nNOS(-/-) cardiomyocytes exhibited significantly higher systolic and diastolic Ca2+ over a range of pacing frequencies. Treatment with the NO donor S-nitroso N-acetyl-penicillamine decreased Ca2+ transients and L-type Ca2+ current in both nNOS(-/-) and WT cardiomyocytes. Furthermore, S-nitrosylation of Ca2+ handling proteins was significantly decreased in nNOS(-/-) myocardium after MI.</AbstractText>Deficiency in nNOS increases ventricular arrhythmia and mortality after MI in mice. The antiarrhythmic effect of nNOS involves inhibition of L-type Ca2+ channel activity and regulation of Ca2+ handling proteins via S-nitrosylation.</AbstractText> |
6,275 | Left atrial remodelling in hypertrophic cardiomyopathy: relation with exercise capacity and biochemical markers of tissue strain and remodelling. | Left atrial remodelling, assessed as left atrial volume (LAV), has been proposed as a good marker of left ventricular diastolic dysfunction. The aim of this study was to analyse the influence of LAV on exercise performance in hypertrophic cardiomyopathy (HCM), and in a subset of subjects, assess the relation of LAV and exercise performance to four biomarkers of disease pathophysiology: matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) (as indices of tissue remodelling), N-terminal portion of pro B-type natriuretic peptide (NT-pro-BNP) (associated with ventricular dysfunction) and C-reactive protein (CRP, an index of inflammation).</AbstractText>We studied 75 consecutive HCM patients (aged 46 +/- 14 years, 56 men) where LAV was calculated assuming the ellipsoid model with two orthogonal planes. LAV was indexed to body surface area. Exercise capacity was evaluated by treadmill exercise test (symptom limited) and assessed with metabolic equivalent units (MET). Basal NT-pro-BNP and CRP levels were measured in 70 patients, whereas MMP-2 and TIMP-1 in 43 patients.</AbstractText>Enlarged LAV was observed in those patients with previous atrial fibrillation (p = 0.016). Mean LAV was greater in patients with impaired functional New York Heart Association (NYHA) class (p < 0.001). LAV correlated with age (Spearman, r: 0.28), higher maximal left ventricular wall thickness (r: 0.32) and raised E/A ratio (r: 0.37) (all p < 0.01). LAV was significantly correlated with NT-pro-BNP values (r: 0.34; p = 0.04), MMP-2 (r: 0.32; p = 0.034), CRP (r: 0.33; p = 0.005) and correlated inversely with MET units (r: -0.39; p < 0.01). In multivariate analysis, MET units were only associated with NT-pro-BNP (p = 0.002) and LAV (p = 0.010).</AbstractText>Enlarged LAV is associated with impaired functional NYHA class and inversely with treadmill exercise capacity. Enlarged LAV is also associated with NT-pro-BNP, MMP-2 and CRP, perhaps as markers of disease severity and tissue remodelling. Age, LAV and NT-pro-BNP are independent predictors of exercise performance.</AbstractText> |
6,276 | [Progress in antiarrhythmic therapy]. | The number of patients with cardiac arrhythmias is increasing in our society with the aged people along with hypertension, diabetes mellitus, metabolic syndrome and ischemic heart diseases. Patient characteristics and therapeutic tools are both diverse at present, and, therefore, clinical evidence is one of the important pieces for selecting therapy suitable for our individual patients. This article reviews recent clinical trials regarding to atrial fibrillation and ventricular tachycardia/fibrillation. We have many powerful knowledge and tools, but at the same time, know well some limitations peculiar to individual therapy for particular arrhythmias. |
6,277 | Ranolazine, an antianginal agent, markedly reduces ventricular arrhythmias induced by ischemia and ischemia-reperfusion. | We tested the effect of the antianginal agent ranolazine on ventricular arrhythmias in an ischemic model using two protocols. In protocol 1, anesthetized rats received either vehicle or ranolazine (10 mg/kg, iv bolus) and were subjected to 5 min of left coronary artery (LCA) occlusion and 5 min of reperfusion with electrocardiogram and blood pressure monitoring. In protocol 2, rats received either vehicle or three doses of ranolazine (iv bolus followed by infusion) and 20 min of LCA occlusion. With protocol 1, ventricular tachycardia (VT) occurred in 9/12 (75%) vehicle-treated rats and 1/11 (9%) ranolazine-treated rats during reperfusion (P = 0.003). Sustained VT occurred in 5/12 (42%) vehicle-treated but 0/11 in ranolazine-treated rats (P = 0.037). The median number of episodes of VT during reperfusion in vehicle and ranolazine groups was 5.5 and 0, respectively (P = 0.0006); median duration of VT was 22.2 and 0 s in vehicle and ranolazine rats, respectively (P = 0.0006). With protocol 2, mortality in the vehicle group was 42 vs. 17% (P = 0.371), 10% (P = 0.162) and 0% (P = 0.0373) with ranolazine at plasma concentrations of 2, 4, and 8 microM, respectively. Ranolazine significantly reduced the incidence of ventricular fibrillation [67% in controls vs. 42% (P = 0.414), 30% (P = 0.198) and 8% (P = 0.0094) in ranolazine at 2, 4, and 8 microM, respectively]. Median number (2.5 vs. 0; P = 0.0431) of sustained VT episodes, incidence of sustained VT (83 vs. 33%, P = 0.0361), and the duration of VT per animal (159 vs. 19 s; P = 0.0410) were also significantly reduced by ranolazine at 8 microM. Ranolazine markedly reduced ischemia-reperfusion induced ventricular arrhythmias. Ranolazine demonstrated promising anti-arrhythmic properties that warrant further investigation. |
6,278 | Increased susceptibility of aged hearts to ventricular fibrillation during oxidative stress. | Oxidative stress with hydrogen peroxide (H(2)O(2)) readily promotes early afterdepolarizations (EADs) and triggered activity (TA) in isolated rat and rabbit ventricular myocytes. Here we examined the effects of H(2)O(2) on arrhythmias in intact Langendorff rat and rabbit hearts using dual-membrane voltage and intracellular calcium optical mapping and glass microelectrode recordings. Young adult rat (3-5 mo, N = 25) and rabbit (3-5 mo, N = 6) hearts exhibited no arrhythmias when perfused with H(2)O(2) (0.1-2 mM) for up to 3 h. However, in 33 out of 35 (94%) aged (24-26 mo) rat hearts, 0.1 mM H(2)O(2) caused EAD-mediated TA, leading to ventricular tachycardia (VT) and fibrillation (VF). Aged rabbits (life span, 8-12 yr) were not available, but 4 of 10 middle-aged rabbits (3-5 yr) developed EADs, TA, VT, and VF. These arrhythmias were suppressed by the reducing agent N-acetylcysteine (2 mM) and CaMKII inhibitor KN-93 (1 microM) but not by its inactive form (KN-92, 1 microM). There were no significant differences between action potential duration (APD) or APD restitution slope before or after H(2)O(2) in aged or young adult rat hearts. In histological sections, however, trichrome staining revealed that aged rat hearts exhibited extensive fibrosis, ranging from 10-90%; middle-aged rabbit hearts had less fibrosis (5-35%), whereas young adult rat and rabbit hearts had <4% fibrosis. In aged rat hearts, EADs and TA arose most frequently (70%) from the left ventricular base where fibrosis was intermediate ( approximately 30%). Computer simulations in two-dimensional tissue incorporating variable degrees of fibrosis showed that intermediate (but not mild or severe) fibrosis promoted EADs and TA. We conclude that in aged ventricles exposed to oxidative stress, fibrosis facilitates the ability of cellular EADs to emerge and generate TA, VT, and VF at the tissue level. |
6,279 | Frequencies and types of arrhythmias in patients with systemic light-chain amyloidosis with cardiac involvement undergoing stem cell transplantation on telemetry monitoring. | Cardiac patients with systemic light-chain amyloidosis have a high incidence of arrhythmias and arrhythmia-related death. We aimed to describe the arrhythmias, determine patient characteristics associated with the development of ventricular arrhythmias, and the utility of telemetric monitoring in patients with cardiac involvement due to AL amyloidosis undergoing stem cell transplantation (SCT). Arrhythmia events of 24 consecutive cardiac patients with AL who underwent SCT with continuous telemetric monitoring were retrospectively reviewed. The relation between number and severity of ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) and baseline clinical, laboratory, and echocardiographic data were determined. Atrial and ventricular arrhythmias were found in all patients. Nonsustained VT was the most frequent event (267 total events). Therapeutic intervention for arrhythmias was required in 20 patients; in 3 patients, life-threatening arrhythmias were detected and treated. There was an inverse relation between VT/VF and cardiac output (r = -0.72, p <0.0001), cardiac index (r = -0.71, p = 0.0001), and stroke volume (r = -0.59, p = 0.0029). There was also a relation between VT/VF and brain natriuretic peptide before SCT (r = 0.47, p = 0.019) and average brain natriuretic peptide levels during admission for SCT (r = 0.62, p = 0.0012), troponin I levels at diagnosis (r = 0.47, p = 0.022), and serum creatinine levels before SCT (r = 0.62, p = 0.001). In conclusion, patients with cardiac amyloidosis undergoing SCT have a high incidence of ventricular and atrial arrhythmias; decreased cardiac output was strongly associated with significant ventricular arrhythmias. Continuous telemetric monitoring contributed to patient safety during SCT. |
6,280 | Association of the parameters derived from the relation between RR intervals and left ventricle performance with a history of heart failure in patients with atrial fibrillation. | Parameters derived from the relation between RR intervals and left ventricular (LV) performance in atrial fibrillation (AF) have been useful to evaluate systolic LV function. This study investigated the association of these parameters with a history of heart failure. Echocardiography was performed in 107 patients with AF. LV outflow peak ejection velocity (Vpe) was adjusted for the effect of pre-preceding RR interval (RR-2) using the logarithmic equation between RR-2 and Vpe. The logarithmic equation between adjusted Vpe and preceding RR interval (RR-1) was calculated in the co-ordinates with RR-1 from 0.6 to 1 second. From this equation, the ratio of slope to Vpe at RR-1 = 1 second (slope/Vpe-1) was obtained. When patients were divided into 2 groups according to a history of heart failure, old age, high slope/Vpe-1, mitral regurgitation, and left atrial enlargement independently predicted the occurrence of heart failure. Fractional shortening was not different between the 2 groups. In patients with normal LV size and without significant regurgitation (n = 69), old age and high slope/Vpe-1 independently predicted the occurrence of heart failure. Areas under the receiver operating characteristics curve of slope/Vpe-1 for identifying heart failure were 0.72 (p <0.000) and 0.74 (p <0.001) in all patients and in patients with normal LV size, respectively. In conclusion, the new parameter, slope/Vpe-1, was one of the most useful predictors for the occurrence of heart failure in AF and was superior to the classic hemodynamic parameters. This parameter might be determined not only by systolic function but also by diastolic function of the left ventricle. |
6,281 | Association of left atrial strain and strain rate assessed by speckle tracking echocardiography with paroxysmal atrial fibrillation. | We hypothesized that contraction of the LA wall could be documented by speckle tracking and could be applied for assessment of LA function. This study tried to identify the association between LA longitudinal strain (LAS) and strain rate (LASR) measured by speckle tracking with paroxysmal atrial fibrillation (PAF).</AbstractText>Fifty-two patients (61 +/- 17 years old, 23 men) with sinus rhythm at baseline referred for the evaluation of episodic palpitation were included. Standard four-chamber and two-chamber views were acquired and analyzed off-line. Peak LAS and LASR were carefully identified as the peak negative inflection of speckle tracking waves after P-wave gated by electrocardiography.</AbstractText>Ten patients (19%) had PAF. LAS, LASR, age, left ventricular end-diastolic dimension, left ventricular mass, LA volume, and mitral early filling-to-annulus early velocity ratio were different between patients with and without PAF. After multivariate analysis, LASR was significantly independently associated with PAF (OR 8.56, 95% CI 1.14-64.02, P = 0.036).</AbstractText>Speckle tracking echocardiography could be used in measurements of LAS and LASR. Decreased negative LASR was independently associated with PAF.</AbstractText> |
6,282 | Persistent ventricular asynchrony after coronary artery bypass surgery predicts cardiac events. | The aim of this study was to identify echocardiographic LV systolic and diastolic measurements that predict clinical events post-coronary artery bypass graft (CABG) surgery.</AbstractText>We collected data from 27 patients (age 70 +/- 7 years) who underwent elective CABG, before and within 6 weeks after surgery. LV systolic function was assessed by conventional echocardiographic parameters. A number of LV filling measurements were also made, which included total isovolumic time (t-IVT), Tei index, and restrictive filling pattern. Postoperative cardiac events were death or hospitalization for chest pain, breathlessness, or arrhythmia.</AbstractText>Patient's follow-up period was 17 +/- 10 months. Of the 27 patients (age 70 +/- 7 years, 22 male), 10 had postoperative cardiac events. LV ejection fraction (EF) and fractional shortening (FS) were lower (P = 0.01, and P = 0.007, respectively), t-IVT longer (P < 0.001), and Tei index was higher (P < 0.001) preoperatively in patients with events compared to those without. The same differences between groups remained after surgery; EF (P = 0.002), FS (P = 0.002), t-IVT (P < 0.001), and Tei index (P < 0.001). T-IVT was the only preoperative predictor of events (P = 0.038) but its postoperative value as well as that of FS predicted events (P = 0.034, and P = 0.042, respectively). T-IVT of 12.2 s/min and FS of 26% were 80% sensitive and 88% specific for predicting postoperative events.</AbstractText>Despite successful surgical revascularization residual impairment of LV systolic function and persistent asynchrony in the form of prolonged t-IVT are associated with postoperative events. Since these abnormalities remained despite full medical therapy, they may thus suggest a need for electrical resynchronization therapy.</AbstractText> |
6,283 | Ventricular mechanical asynchrony in patients with different degrees of systolic dysfunction: results from AVE Registry by the Italian Society of Cardiovascular Echography (SIEC). | The aim of the study was to compare the prevalence of interventricular and intraventricular asynchrony in patients with different degrees of left ventricular (LV) dysfunction.</AbstractText>We enrolled 182 patients (male 79%, mean age 64 +/- 11 years) with LV ejection fraction (EF) < 50% and identified two groups: Group A (n = 79) with mild-to-moderate LV dysfunction (EF between 36% and 49%) and Group B (n = 103) with severe dysfunction (EF <or= 35%). An echocardiogram was performed in all patients and a delay longer than 40 msec in the time difference between the aortic and pulmonary preejection intervals was considered as an index of interventricular asynchrony. The electromechanical delays were assessed by pulsed tissue Doppler technique. A time difference between the earliest and the latest segment greater than 40 msec was considered the cutoff for intraventricular asynchrony. The sum of asynchrony was calculated by adding to the LV intraventricular delay the delay between the lateral basal right ventricular segment and the most delayed LV basal segment.</AbstractText>The prevalence of interventricular asynchrony was lower among Group A patients (19.8% vs. 37.9%; P = 0.007) while the prevalence of intraventricular asynchrony did not differ between groups (32.9% vs. 44% in Group A and Group B respectively; P = 0.18). The sum of asynchrony (cutoff >102 msec) did not differ between groups either (29.9% vs. 35.9%; P = 0.39).</AbstractText>The prevalence of intraventricular asynchrony is independent of the LV systolic dysfunction severity. This could indicate the potential role of cardiac resynchronization therapy in patients with mild-moderate systolic dysfunction.</AbstractText> |
6,284 | Sex differences in cerebral injury after severe haemorrhage and ventricular fibrillation in pigs. | Experimental studies of haemorrhagic shock have documented a superior haemodynamic response and a better outcome in female animals as compared with male controls. Such sexual dimorphism has, nevertheless, not been reported after circulatory arrest that follows exsanguination and shock. We aimed to study differences in cerebral injury markers after exsanguination cardiac arrest in pre-pubertal piglets. The hypothesis was that cerebral injury is less extensive in female animals, and that this difference is independent of sexual hormones or choice of resuscitative fluid.</AbstractText>Thirty-two sexually immature piglets (14 males and 18 females) were subjected to 5 min of haemorrhagic shock followed by 2 min of ventricular fibrillation and 8 min of cardiopulmonary resuscitation, using three resuscitation fluid regimens (whole blood, hypertonic saline and dextran, or acetated Ringers' solution plus whole blood and methylene blue). Haemodynamic values, cellular markers of brain injury and brain histology were studied.</AbstractText>After successful resuscitation, female piglets had significantly greater cerebral cortical blood flow, tended to have lower S-100beta values and a lower cerebral oxygen extraction ratio. Besides, in female animals, systemic and cerebral venous acidosis were mitigated. Female piglets exhibited a significantly smaller increase in neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) expression in their cerebral cortex, smaller blood-brain-barrier (BBB) disruption and significantly smaller neuronal injury.</AbstractText>After resuscitation from haemorrhagic circulatory arrest, cerebral reperfusion is greater, and BBB permeability and neuronal injury is smaller in female piglets. An increased cerebral cortical iNOS and nNOS expression in males implies a mechanistic relationship with post-resuscitation neuronal injury and warrants further investigation.</AbstractText> |
6,285 | [Reoperation through right thoracotomy for mitral regurgitation after coronary artery bypass grafting; report of a case]. | A 53-year-old male patient developed severe mitral regurgitation 6 years after coronary artery bypass grafting (CABG) with a left internal thoracic artery and 2 saphenous veins. The left ventriculography showed severe mitral regurgitation and slight decrease in left ventricular function. The coronary arteriography showed all grafts being patent. The median re-sternotomy was avoided because of the risk for injury of bypass grafts, and the right anterolateral thoracotomy was chosen. Mitral valve replacement was performed under moderate hypothermia and ventricular fibrillation without aortic cross clamping. The postoperative course was uneventful. Right anterolateral thoracotomy is considered to be a superior approach to the mitral valve surgery in the patients with previous CABG. |
6,286 | Vulnerability to unidirectional conduction block and reentry in rabbit left ventricular wedge preparation: effects of stimulation sequence and location. | Many factors influence the initiation of unidirectional conduction block and reentry. To explore the influential factors on the temporal vulnerable window of the unidirectional conduction block, we investigated the effect of stimulation sequence and location on the temporal vulnerability in epicardial and endocardial sites in an arterially perfused rabbit left ventricular wedge preparation at three basic cycle lengths (BCL) of 2,000, 1,000 and 500 ms. An extrastimulus (S2) was introduced at coupling intervals incremented by 1 ms to scan the entire diastolic interval. The results showed that the vulnerable window increased with the lengthening of BCL, which ranged from 48.55 +/- 18.04 ms at BCL of 500 ms to 92.50 +/- 25.59 ms at BCL of 2,000 ms for endocardial, and is a similar style for epicardial from 21.00 +/- 14.02 ms at BCL of 500 ms to 75.71 +/- 16.34 ms at BCL of 2,000 ms (P < 0.05). The vulnerable window of endocardial was wider than that of epicardial (P < 0.05). Furthermore, the window size for reentry was about 39% smaller than that for unidirectional conduction block. Meanwhile, we found that increasing the number of premature beats enlarged the vulnerable window markedly due to enhanced transmural dispersion of repolarization (TDR) of ventricle. The vulnerable window is an effective index to evaluate the increased risk for unidirectional conduction block. Therefore, the factors that increase the vulnerable window are associated with the higher incidence of ventricular arrhythmias. |
6,287 | Predicting successful pulmonary vein isolation in patients with atrial fibrillation by brain natriuretic Peptide plasma levels. | Catheter ablation for atrial fibrillation is a clinically established treatment by now while success rate varies between 60% and 85%. Interventional treatment of atrial fibrillation is still a challenging technique associated with a long procedure time and risk of major complications in up to 6 % of treated patients. The aim of this study was to investigate the predictive value of plasma brain natriuretic peptide (BNP) in patients undergoing pulmonary vein isolation concerning stable sinus rhythm after ablation.</AbstractText>In 68 consecutive patients with atrial fibrillation (AF) and normal left ventricular ejection fraction, BNP was measured at baseline before pulmonary vein isolation (PVI). All patients received a 7-days-holter monitoring 3 months after radiofrequency (RF) ablation in order to detect recurrent AF episodes.</AbstractText>48 patients with paroxysmal and 20 patients with persistent AF were enrolled. Baseline BNP was significantly higher in patients with persistent AF compared to patients with paroxysmal AF (145,5 pg/ml vs. 84,4 pg/ml; p<0,05). 3 months after PVI 38 patients (79,1%) with paroxysmal AF had a stable sinus rhythm documented on 7-days-holter monitoring, where as in 10 patients (20,9%) AF episodes were detected. Patients with a successful PVI showed significantly lower BNP plasma levels at baseline compared to patients with AF recurrrence (68,7 pg/ml vs. 144,1 pg/ml; p<0,05). In patients with persistent AF 55% (11 cases) had no recurrence of AF at 3 months 7-days holter and in 9 patients (45%) AF recurred. BNP plasma levels at baseline were lower in patients with stable sinusrhythm after 3 months compared to the group of recurrent AF (105,8 pg/ml vs. 193,3 pg/ml; p=0,11).</AbstractText>Patients with AF and low preprocedural BNP plasma levels showed a better outcome after PVI. Thus BNP may be helpful in patient selection for a successful treatment of AF by PVI.</AbstractText> |
6,288 | A prediction model for out-of-hospital cardiopulmonary resuscitation. | We created a prediction model to be used in cardiopulmonary resuscitation (CPR) attempts as a decision tool to omit futile CPR attempts and to save resources.</AbstractText>In this post hoc analysis, we assessed predictive parameters for neurological recovery after successful CPR. The original study was designed as a blinded, randomized, prospective, controlled, multicenter clinical trial.</AbstractText>We identified 1166 prehospital cardiac arrest patients being treated with advanced cardiac life support. Seven hundred eighty-six of 1166 patients (67.4%) died at the scene and 380 of 1166 (32.6%) were brought to the hospital. Two hundred sixty-five of 1166 patients (22.7%) died in the hospital. One hundred fifteen of 1166 (9.8%) were discharged from the hospital and 92 of the 115 patients (80%) could be followed-up. Good cerebral performance was regained by 54% of discharged patients (50 of 92 patients). In 46% of patients (42/92), unconsciousness or severe disability remained. Ventricular fibrillation was more likely to have occurred in patients with good neurological recovery (42/50 = 84.0%), whereas asystole was more likely in patients with poor neurological recovery (9/42 = 21.4%). A score was developed to predict the probability of death using logistic regression analysis. Predicting death in the hospital revealed a sensitivity of 99.8% (953/955), but only a specificity of 2.9% (3/104; threshold 0.5). Predicting survival until discharge from the hospital revealed a sensitivity of 99% (103/104), but only a specificity of 8% (72/955; threshold 0.99). A receiver operating characteristic curve yielded an area under the curve of 0.795 (0.751-0.839) at a confidence interval of 95%.</AbstractText>For out-of-hospital patients with cardiac arrest, parameters documented in the field did not allow accurate prediction of hospital survival.</AbstractText> |
6,289 | Detection of ventricular fibrillation using empirical mode decomposition and Bayes decision theory. | Ventricular fibrillation (VF) is the most serious variety of arrhythmia which requires quick and accurate detection to save lives. In this paper, we propose an empirical mode decomposition (EMD) based algorithm for VF detection. The intrinsic mode functions (IMFs) of VF are orthogonal whereas the lower order IMFs of normal sinus rhythm (NSR) are not. The orthogonality indices derived from the first three consecutive intrinsic mode functions (IMFs) of NSR and VF are used for their discrimination. The proposed technique is applied to the MIT-BIH arrhythmia database. The accuracy of detection of VF is 99.70% for a window length of 3s. This early estimate of VF may be useful in emergency cases where defibrillators are to be applied. Comparative results with the existing methods in terms of quality parameters and integrated receiver operating characteristic (IROC) are presented. |
6,290 | Myocardial ischemia with left ventricular outflow obstruction. | We report an unusual case of a 32-year old man who was treated for a hypertrophic obstructive cardiomyopathy (HOCM) with a DDD pacing with short AV delay reduction in the past. Without prior notice the patient developed ventricular fibrillation and an invasive cardiac diagnostic was performed, which revealed a myocardial bridging around of the left anterior descending artery (LAD). We suspected ischemia that could be either related to LAD artery compression or perfusion abnormalities due to AV delay reduction with related to diastolic dysfunction. |
6,291 | Prevention of inappropriate ICD shocks in patients with Brugada syndrome. | In Brugada syndrome implantable cardioverter defibrillator (ICD) therapy is associated with a high rate of inappropriate therapies, mainly due to supraventricular tachyarrhythmias (SVT) (2.7-14.1%/year). Aim of the present study was to evaluate a single ventricular fibrillation (VF) detection zone with a high cut-off rate with respect to prevention of inappropriate ICD shock due to SVT and safety of this programming.</AbstractText>Sixty-one consecutive patients (mean age 42.6 +/- 12.9 years; 41 males) diagnosed with Brugada syndrome and implanted with an ICD were included. ICDs were prospectively programmed with a single VF detection zone and a cut-off rate of 222 beats/minute (bpm). A maximum of six shocks with the maximal shock energy were programmed. The minimal follow-up was 1 year.</AbstractText>During a follow-up of 47.6 +/- 23.1 months seven patients (2.91%/year) received appropriate ICD shocks. No patient suffered from syncope or died. Five patients (2.07%/year) received inappropriate ICD shocks: four patients due to T-wave oversensing and only one patient (0.4%/year) due to SVT (atrial fibrillation with a ventricular rate of >222 bpm).</AbstractText>Programming of a single, high-rate VF zone in patients with Brugada syndrome and an implanted defibrillator is safe. Such programming may be associated with reduced inappropriate defibrillator discharges. A single detection zone with a high VF cut-off rate can be recommended in patients with Brugada syndrome.</AbstractText> |
6,292 | Echo Doppler guidance for atrial fibrillation ablation: recognition of primary electropathy. | Atrial fibrillation (AF) is a multivariable disease. Young patients with paroxysmal AF without structural cardiac abnormality ("lone AF") likely have a primary electropathy with excellent results from radiofrequency ablation. However, with persistent AF with cardiac abnormalities, including left atrial enlargement and systolic ventricular dysfunction (ejection fraction percent), the electropathy is considered secondary and ablation results poor. We describe a case with persistent AF, depressed systolic function, and marked left atrial enlargement but without echo Doppler evidence of diastolic dysfunction. At electrophysiology study, findings were consistent with a primary electropathy, and the patient did well following ablation. |
6,293 | [Atrial pacing for prevention of atrial fibrillation. Influence of septal atrial pacing, atrial overdrive and AV-delay-optimization on atrial fibrillation burden]. | Atrial overdrive and optimized interatrial conduction time can reduce atrial fibrillation (AF). Increased ventricular stimulation results in a higher incidence of atrial fibrillation.</AbstractText>In 25 patients with paroxysmal AF, a dual-chamber pacemaker (Identity DR 5370, St. Jude Medical) was implanted. Atrial leads were placed randomly either septal (n=12) or conventional (n=13). Dynamic atrial overdrive (DAO) was activated and the AV delay was optimized according to Koglek's method. After 3, 6, 9, and 12 months automatic mode switch (AF burden) was analysed.</AbstractText>No difference in implantation parameters were observed between groups. Technical implantation parameters were in the normal range for both groups. After 12 months patients in the septal group had less AF burden (1% vs. 7%, p=0.06), and the total number of AF episodes was reduced.</AbstractText>Septal pacing is safe. In combination with DAO and AV delay optimization it may reduce the AF burden, which can be observed after 12 months.</AbstractText> |
6,294 | Racial differences in survival after in-hospital cardiac arrest. | Racial differences in survival have not been previously studied after in-hospital cardiac arrest, an event for which access to care is not likely to influence treatment.</AbstractText>To estimate racial differences in survival for patients with in-hospital cardiac arrests and examine the association of sociodemographic and clinical factors and the admitting hospital with racial differences in survival.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">Cohort study of 10,011 patients with cardiac arrests due to ventricular fibrillation or pulseless ventricular tachycardia enrolled between January 1, 2000, and February 29, 2008, at 274 hospitals within the National Registry of Cardiopulmonary Resuscitation.</AbstractText>Survival to hospital discharge; successful resuscitation from initial arrest and postresuscitation survival (secondary outcome measures).</AbstractText>Included were 1883 black patients (18.8%) and 8128 white patients (81.2%). Rates of survival to discharge were lower for black patients (25.2%) than for white patients (37.4%) (unadjusted relative rate [RR], 0.73; 95% confidence interval [CI], 0.67-0.79). Unadjusted racial differences narrowed after adjusting for patient characteristics (adjusted RR, 0.81 [95% CI, 0.75-0.88]; P < .001) and diminished further after additional adjustment for hospital site (adjusted RR, 0.89 [95% CI, 0.82-0.96]; P = .002). Lower rates of survival to discharge for blacks reflected lower rates of both successful resuscitation (55.8% vs 67.4% for whites; unadjusted RR, 0.84 [95% CI, 0.81-0.88]) and postresuscitation survival (45.2% vs 55.5% for whites; unadjusted RR, 0.85 [95% CI, 0.79-0.91]). Adjustment for the hospital site at which patients received care explained a substantial portion of the racial differences in successful resuscitation (adjusted RR, 0.92 [95% CI, 0.88-0.96]; P < .001) and eliminated the racial differences in postresuscitation survival (adjusted RR, 0.99 [95% CI, 0.92-1.06]; P = .68).</AbstractText>Black patients with in-hospital cardiac arrest were significantly less likely to survive to discharge than white patients, with lower rates of survival during both the immediate resuscitation and postresuscitation periods. Much of the racial difference was associated with the hospital center in which black patients received care.</AbstractText> |
6,295 | Is there a role for digoxin in atrial fibrillation without heart failure? | Digoxin remains one of the most frequently prescribed drugs in the management of atrial fibrillation. The main indications for digoxin in atrial fibrillation are restoration of sinus rhythm, prevention of recurrence and slowing of the ventricular rate. However, none of these effects of digoxin have been confirmed in placebo controlled studies. In addition, recent reports suggest increased mortality in patients with atrial fibrillation without heart failure taking digoxin. The aim of this article is to review the role of digoxin in atrial fibrillation without heart failure. |
6,296 | Inappropriate cardioverter-defibrillator discharge continues to be a major problem in clinical practice. | The purpose of this study was to determine the rate and causes of inappropriate rhythm detection, and to compare adequacy of ventricular arrhythmia detection by single-chamber and dual-chamber cardioverter-defibrillators (ICD).</AbstractText>We evaluated 190 patients (age 57.2 +/- 11.2 years) with ICD.</AbstractText><AbstractText Label="FOLLOW-UP" NlmCategory="RESULTS">34.3 +/- +/- 22 months. Dual-chamber ICD was used in 54 patients.</AbstractText>We evaluated 2244 arrhythmia events recognized as of ventricular origin, including ventricular tachycardia and ventricular fibrillation. 431 events (19.2%) were recognized erroneously and resulted in an inappropriate ICD discharge. Most cases of inappropriate therapies (182 events, 42.23%) were due to atrial fibrillation or flutter. Overall, inappropriate arrhythmia detection was found in 64 (33.6%) of 190 patients. In terms of the number of affected patients, the most common cause of inappropriate ICD discharge was sinus tachycardia - 23 (12.1%) patients, followed by atrial fibrillation - 16 (8.4%) patients. Among 54 patients with dual-chamber ICD, inappropriate therapy was noted in 21 (38.8%) patients, (T wave oversensing, sinus tachycardia and atrial fibrillation etc.). No significant difference was seen in the rate of inappropriate therapy due to a rapid supraventricular rhythm between patients with single-chamber versus dual-chamber ICD. In contrast, patients with single-chamber ICD more often experienced inappropriate therapy due to atrial fibrillation (155 vs. 28 patients) and sinus tachycardia (66 vs. 9 patients).</AbstractText>Despite of introduction of new generations of ICDs, the problem of inappropriate ICD discharge could not be eliminated. The major problem is distinction between supraventricular arrhythmia and ventricular tachyarrhythmia.</AbstractText> |
6,297 | Chest compression fraction determines survival in patients with out-of-hospital ventricular fibrillation. | Quality cardiopulmonary resuscitation contributes to cardiac arrest survival. The proportion of time in which chest compressions are performed in each minute of cardiopulmonary resuscitation is an important modifiable aspect of quality cardiopulmonary resuscitation. We sought to estimate the effect of an increasing proportion of time spent performing chest compressions during cardiac arrest on survival to hospital discharge in patients with out-of-hospital ventricular fibrillation or pulseless ventricular tachycardia.</AbstractText>This is a prospective observational cohort study of adult patients from the Resuscitation Outcomes Consortium Cardiac Arrest Epistry with confirmed ventricular fibrillation or ventricular tachycardia, no defibrillation before emergency medical services arrival, electronically recorded cardiopulmonary resuscitation before the first shock, and a confirmed outcome. Patients were followed up to discharge from the hospital or death. Of the 506 cases, the mean age was 64 years, 80% were male, 71% were witnessed by a bystander, 51% received bystander cardiopulmonary resuscitation, 34% occurred in a public location, and 23% survived. After adjustment for age, gender, location, bystander cardiopulmonary resuscitation, bystander witness status, and response time, the odds ratios of surviving to hospital discharge in the 2 highest categories of chest compression fraction compared with the reference category were 3.01 (95% confidence interval 1.37 to 6.58) and 2.33 (95% confidence interval 0.96 to 5.63). The estimated adjusted linear effect on odds ratio of survival for a 10% change in chest compression fraction was 1.11 (95% confidence interval 1.01 to 1.21).</AbstractText>An increased chest compression fraction is independently predictive of better survival in patients who experience a prehospital ventricular fibrillation/tachycardia cardiac arrest.</AbstractText> |
6,298 | Extracellular matrix remodeling in atrial fibrosis: mechanisms and implications in atrial fibrillation. | Atrial fibrosis has been strongly associated with the presence of heart diseases/arrhythmias, including congestive heart failure (CHF) and atrial fibrillation (AF). Inducibility of AF as a result of atrial fibrosis has been the subject of intense recent investigation since it is the most commonly encountered arrhythmia in adults and can substantially increase the risk of premature death. Rhythm and rate control drugs as well as surgical interventions are used as therapies for AF; however, increased attention has been diverted to mineralocorticoid receptor (MR) antagonists including spironolactone as potential therapies for human AF because of their positive effects on reducing atrial fibrosis and associated AF in animal models. Spironolactone has been shown to exert positive effects in human patients with heart failure; however, the mechanisms and effects in human atrial fibrosis and AF remain undetermined. This review will discuss and highlight developments on (i) the relationship between atrial fibrosis and AF, (ii) spironolactone, as a drug targeted to atrial fibrosis and AF, as well as (iii) the distinct and common mechanisms important for regulating atrial and ventricular fibrosis, inclusive of the key extracellular matrix regulatory proteins involved. |
6,299 | Combination pharmacotherapy in the treatment of experimental cardiac arrest. | Full recovery after cardiopulmonary resuscitation (CPR) is poor. We hypothesized that the coadministration of epinephrine, a beta-blocker such as atenolol, and a calcium sensitizer such as levosimendan during CPR would improve survival and postresuscitation myocardial function.</AbstractText>Ventricular fibrillation was induced in 60 piglets, which were left untreated for 8 minutes before attempted resuscitation. Animals were randomized into 4 groups (n = 15), to receive epinephrine (group E), epinephrine + atenolol (group E + A), epinephrine + levosimendan (group E + L) and epinephrine + atenolol + levosimendan (group E + A + L) during CPR. Electrical defibrillation was attempted 2 minutes after drug administration.</AbstractText>Five animals in group E survived for 48 hours in comparison to 8 animals in groups E + A and E + L and 12 animals in group E + A + L. Postresuscitation cardiac output was significantly better in the animals of group E + A + L. Troponin I remained significantly lower in groups E + A and E + A + L. Serum astroglial protein (S-100) and neuron-specific enolase values in group E + L and E + A + L were statistically lower than those measured in groups E and E + A during the entire observation period. The neurologic alertness score was higher in group E + A + L compared to groups E and E + A.</AbstractText>The administration of a drug combination of epinephrine + atenolol + levosimendan, when given during CPR, in a pig model of cardiac arrest, results in improved 48-hour survival and improves postresuscitation cardiac function.</AbstractText> |
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