Unnamed: 0
int64 0
2.34M
| title
stringlengths 5
21.5M
| abst
stringlengths 1
21.5M
|
|---|---|---|
2,000 | Randomized controlled trial of fixed rate versus rate responsive pacing after radiofrequency atrioventricular junction ablation: quality of life, ventricular refractoriness, and paced QT dispersion. | Ablation of the AV junction is a widely accepted treatment of drug-refractory atrial fibrillation. Long-term pacing of the right ventricular (RV) apex following AV junction ablation can result in adverse cardiac remodeling. However, anecdotal studies report that pacing too slowly following AV junction ablation was associated with propensity to sudden cardiac death. The aim of this study was to provide information about the balance between measures of quality of life versus measures of electrical remodeling achieved by pacing with different rate modalities in a randomized pilot clinical trial.</AbstractText>Patients with permanent atrial fibrillation were randomized to VVI (80 beats/min) versus VVIR (minimum rate 80 beats/min), whereas patients with paroxysmal atrial fibrillation were randomized to DDI versus DDDR pacing at discharge from hospital. Serially, measurements of exercise capacity, quality of life, cycle length dependence of QT dispersion (QTdisp), RV refractoriness, and the incidence of nonsustained ventricular tachycardia were made in 28 patients over a 6-month follow-up period. Time-dependent increases in QTdisp were observed in patients randomized to the rate responsive mode (RR-ON) but only when paced at 40 beats/min. This was paralleled by time-dependent increases in RV refractoriness (270 +/- 11 ms at baseline to 302 +/- 5 ms at 6 months) in patients with RR-ON. RR-ON also was associated with trends to an increasing incidence of episodes of nonsustained ventricular tachycardia and worsening of some measures of quality of life. Exercise capacity was not substantially different in the randomized groups.</AbstractText>Rate responsive pacing results in electrical remodeling of the ventricle following AV junction ablation, but exercise capacity was similar in groups with RR-ON or RR-OFF.</AbstractText> |
2,001 | Hydrofluoric acid-induced burns and life-threatening systemic poisoning--favorable outcome after hemodialysis. | Skin contact with hydrofluoric acid (HF) may cause serious burns and life-threatening systemic poisoning. The use of hemodialysis in fluoride intoxication after severe dermal exposure to HF has been recommended but not reported.</AbstractText>A 46-year-old previously healthy man had 7% of his body surface exposed to 71% HE Despite prompt management, with subsequent normalization of the serum electrolytes, recurrent ventricular fibrillation occurred. On clinical suspicion of fluoride-induced cardiotoxicity, acute hemodialysis was performed. The circulatory status stabilized and the patient fully recovered. High fluoride levels in the urine and serum were confirmed by the laboratory.</AbstractText>There is no ultimate proof that the favorable outcome in this case was significantly attributable to the dialysis. However, most reported exposures of this magnitude have resulted in fatal poisoning. As our patient had normal serum electrolytes and no hypoxia or acidosis at the time of his arrhythmias, it was decided that all efforts should be focused on removing fluoride from his blood. The rationale for performing hemodialysis for this purpose is clear, even though such intervention is more obviously indicated in patients with renal failure.</AbstractText>Hemodialysis may be an effective and potentially lifesaving additional treatment for severe exposure to HF when standard management has proven insufficient.</AbstractText> |
2,002 | Amiodarone: guidelines for use and monitoring. | Amiodarone is a potent antiarrhythmic agent that is used to treat ventricular arrhythmias and atrial fibrillation. The drug prevents the recurrence of life-threatening ventricular arrhythmias and produces a modest reduction of sudden deaths in high-risk patients. Amiodarone is more effective than sotalol or propafenone in preventing recurrent atrial fibrillation in patients for whom a rhythm-control strategy is chosen. When long-term amiodarone therapy is used, potential drug toxicity and interactions must be considered. The dosage of amiodarone should be kept at the lowest effective level. In patients who also are taking digoxin and warfarin, physicians must pay close attention to digoxin levels and prothrombin time, keeping in mind that the effects of interaction with amiodarone do not peak until seven weeks after the initiation of concomitant therapy. Laboratory studies to assess liver and thyroid function should be performed at least every six months. |
2,003 | Feasibility and safety of transeophageal atrial pacing stress echocardiography in patients with known or suspected coronary artery disease. | To investigate the feasibility and safety of the transesophageal atrial pacing stress test combined with echocardiography (TAPSE) 1,727 TAPSE tests were performed on 1,641 patients consecutively referred to our echocardiographic laboratory for nonexercise stress testing (1,319 men; mean age 60 +/- 9 years; 34% of whom were outpatients). Wall motion abnormalities were present at baseline echocardiography in 975 cases (56%). TAPSE was feasible in 1,648 cases (95.4%). It was not feasible in 79 patients due to failure of positioning the transnasal catheter (n=11), the patient's intolerance of esophageal stimulation (n=24), failure to obtain any or stable atrial capture (n=36), or because the echocardiogram could not be evaluated at the peak of the test (n=8). TAPSE was diagnostic in 1,584 cases (96% of the feasible tests, 92% of all attempts). TAPSE was nondiagnostic in 64 cases (4% of the feasible tests) due to second-degree atrioventricular type I block resistance to atropine administration with failure to achieve 85% of the age-predicted maximum heart rate (n=59) or due to side effects, such as arrhythmias (n=3) or hypertension (n=2), which required premature interruption of the test. There were no major complications (death, myocardial infarction, or life-threatening arrhythmias). There were 28 instances of minor complications that comprised transient arrhythmias, including atrial fibrillation (n=8), paroxysmal supraventricular tachycardia (n=6), automatic atrial tachycardia (n=1), sinus arrest (n=1), atrioventricular junctional rhythm (n=2), ectopic atrial rhythm (n=2), nonsustained ventricular tachycardia (maximum 6 beats, n=3), hypotension (n=1), and hypertension (n=4) leading to interruption of the test. Only 5 complications hampered a diagnostic result, whereas 18 occurred during or after a positive test and 5 during a negative, but diagnostic, test. Thus, TAPSE is a highly feasible and very safe stress test. It gives high percentage of diagnostic tests and may represent a valid alternative to pharmacologic stressors. |
2,004 | Usefulness of statin drugs in protecting against atrial fibrillation in patients with coronary artery disease. | Atrial fibrillation (AF) is prevalent in the elderly, in patients with hypertension, and in patients with coronary artery disease (CAD). We hypothesized that statin therapy might be effective in preventing AF in patients with CAD and examined this hypothesis in a sample of patients with chronic stable CAD without AF, followed prospectively at a large outpatient cardiology practice. The association between statin use and the risk of developing AF was examined univariately and then with adjustment for potential confounding factors. Four hundred forty-nine men and women between the ages of 40 and 87 years were followed for an average of 5 years. Fifty-two patients (12%) developed AF during follow-up. Statin therapy was used by 59% of the patients during the study period and was associated with a significantly reduced risk of developing AF (crude odds ratio, 0.48, 95% confidence interval 0.28 to 0.83). This association remained significant after adjustment for potential confounders, including age, hypertension, left ventricular systolic function, occurrence of heart failure or acute ischemic events, and baseline cholesterol and changes in cholesterol levels (adjusted odds ratio 0.37, 95% confidence interval 0.18 to 0.76). Use of statins in patients with chronic stable CAD appears to be protective against AF. The underlying mechanism for this effect is unknown but appears to be independent of the reduction in serum cholesterol levels. |
2,005 | Implantable cardioverter defibrillator events in patients with asymptomatic nonsustained ventricular tachycardia: is device implantation justified? | Primary prevention trials have demonstrated that patients with coronary disease, reduced left ventricular function, and nonsustained ventricular tachycardia (NSVT) have improved survival with implantable cardioverter defibrillator (ICD) therapy, presumably secondary to effective termination of life-threatening arrhythmias. However, stored intracardiac electrograms were not always available and specific arrhythmias leading to ICD therapy were not always known. We examined the occurrence of ICD events in 51 consecutive patients who match the described patient profile to determine the frequency of appropriate and inappropriate ICD therapy. ICD detections were noted in 18 (35%) patients during a median follow-up period of 13.1 months. Appropriate therapy for sustained ventricular tachycardia (VT)/ventricular fibrillation (VF) occurred in 11 (22%) patients, with appropriate shocks in 8 (16%) patients and appropriate antitachycardia pacing (ATP) in 4 (8%) patients. The time to first appropriate therapy occurred at a mean of 17 +/- 12 months (median 18 months, range 3-36 months). Inappropriate therapy occurred in 5 (10%) patients with inappropriate shocks in 4 patients and inappropriate ATP in 2 patients. Inappropriate therapy was delivered for supraventricular arrhythmias (SVAs) in 4 patients and for T wave oversensing in 1 patient. The reason for shock therapy was unknown in 1 patient (2%) due to ICD malfunction. The mean arrhythmia rate leading to appropriate therapy for VT/VF was 232 +/- 72 beats/min (range 181-400 beats/min), and the mean rate leading to inappropriate therapy for SVT was 168 +/- 10 beats/min (range 160-180 beats/min). Patients with coronary disease and asymptomatic NSVT commonly receive appropriate defibrillator therapy. These results support the need for ICD implantation for primary prevention, with attention to careful programming of the detection rate to prevent inappropriate therapy. |
2,006 | Factors determining ICD implantation in drug therapy patients after termination of antiarrythmics versus implantable defibrillators trial. | Because of a significant survival benefit in the defibrillator arm of the Antiarrhythmics versus Implantable Defibrillator (AVID) Trial, patients in the antiarrhythmic drug (AAD) arm were advised to undergo ICD implantation. Despite this recommendation, ICD implantation in AAD patients was variable, with a large number of patients not undergoing ICD implantation. Patients were grouped by those who had been on AAD < 1 year (n = 111) and those on AAD > 1 year (n = 223). Multiple clinical and socioeconomic factors were evaluated to identify those who might be associated with a decision to implant an ICD. The primary reason for patients not undergoing ICD implantation was collected, as well as reasons for a delayed implantation, occurring later than 3 months from study termination. Of 111 patients on AAD for less than 1 year, 53 received an ICD within 3 months compared to 40/223 patients on AAD for more than 1 year (P < 0.001). Patient refusal was the most common reason to not implant an ICD in patients on drug < 1 year; physician recommendation against implantation was the most common in patients on drug > 1 year. Multivariate analysis showed ICD recipients on AAD < 1 year were more likely to be working and have a history of myocardial infarction (MI), while those on AAD > 1 year were more likely to be working, have a history of MI and ventricular fibrillation, and less likely to have experienced syncope, as compared to those who did not get an ICD. Having private insurance may have played a role in younger patients receiving an ICD. |
2,007 | Effects of L-carnitine and its derivatives on postischemic cardiac function, ventricular fibrillation and necrotic and apoptotic cardiomyocyte death in isolated rat hearts. | The study aimed to examine whether L-carnitine and its derivatives, acetyl-L-carnitine and propionyl-L-carnitine, were equally effective and able to improve postischemic cardiac function, reduce the incidence of reperfusion-induced ventricular fibrillation, infarct size, and apoptotic cell death in ischemic/reperfused isolated rat hearts. There are several studies indicating that L-carnitine, a naturally occurring amino acid and an essential cofactor, can improve mechanical function and substrate metabolism not only in hypertrophied or failing myocardium but also in ischemic/reperfused hearts. The effects of L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine, on the recovery of heart function, incidence of reperfusion-induced ventricular fibrillation (VF), infarct size, and apoptotic cell death after 30 min ischemia followed by 120 min reperfusion were studied in isolated working rat hearts. Hearts were perfused with various concentrations of L-carnitine (0.5 and 5 mM), acetyl-L-carnitine (0.5 and 5 mM), and propionyl-L-carnitine (0.05, 0.5, and 5 mM), respectively, for 10 min before the induction of ischemia. Postischemic recovery of CF, AF, and LVDP was significantly improved in all groups perfused with 5 mM of L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine. Significant postischemic ventricular recovery was noticed in the hearts perfused with 0.5 mM of propionyl-L-carnitine, but not with the same concentration of L-carnitine or L-acetyl carnitine. The incidence of reperfusion VF was reduced from its control value of 90 to 10% (p < 0.05) in hearts perfused with 5 mM of propionyl-L-carnitine only. Other doses of various carnitines failed to reduce the incidence of VF. The protection in CF, AF, LVDP, and VF reflected in a reduction in infarct size and apoptotic cell death in hearts treated with various concentrations of carnitine derivatives. The difference between effectiveness of various carnitines on the recovery of postischemic myocardium may be explained by different membrane permeability properties of carnitine and its derivatives. |
2,008 | Combined cox maze procedure, septal myectomy, and mitral valve replacement for severe hypertrophic obstructive cardiomyopathy complicated by chronic atrial fibrillation. | Atrial fibrillation (AF) has been reported to be an important prognostic indicator for clinical deterioration particularly in patients with hypertrophic obstructive cardiomyopathy (HOCM). A 66-year-old female complained of severe exertional dyspnea and tachycardia, which were resistant to medical treatments. Doppler echocardiography demonstrated a peak left ventricular outflow tract (LVOT) gradient of 117 mmHg at rest. A catheter examination revealed left ventricular end diastolic pressure of 34 mmHg, a cardiac index of 1.94 L/minute/m(2), and a peak LVOT gradient of 70 mmHg at rest. A transaortic septal myotomy/myectomy was performed first, and Cox maze III procedure was performed through the right and left atrium followed by mitral valve replacement. The patient recovered dramatically except for temporary complete atrioventricular block. One year after operation, the patient is doing well with sinus rhythm and the echocardiogram revealed a peak LVOT pressure gradient of 7.6 mmHg at rest. This surgical approach might be recommended for the treatment of AF in HOCM. (Ann Thorac Cardiovasc Surg 2003; 9: 323-5) |
2,009 | [Inpatient cardiac defibrillation: efficacy of bipolar sinusoidal impulse]. | Efficacy of external defibrillation of the heart with low energy (</=65-195 J) bipolar quasi sinusoidal discharges was studied in 76 patients with induced, primary (overall 70 episodes), and secondary (88 episodes) ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VT) with or without acute myocardial infarction. Maximal effective discharge energy used for termination of induced and primary VF or VT was 90 J in 10 of 66 patients (15%) ). Meanwhile discharge energy 165-193 J was required for termination of secondary VF in 6 of 34 patients (18%). Overall efficacy of cardiac defibrillation with discharge energies </=115 and </=193 J was 92 and 100%, respectively. Success of resuscitation in patients with prolonged (2-28 min) primary and secondary VF was 82 and 68%, respectively. VF duration before first discharge (0,5-8 min) did not affect significantly magnitude of effective energy in interval between 90 and 193 J. However lower energy discharges were less effective when duration of fibrillation exceeded 30 sec. |
2,010 | Acute coronary syndrome: potassium, magnesium and cardiac arrhythmia. | Cardiac arrhythmia is often present in patients with acute coronary syndrome (ACS) and may be due to the electrolyte imbalance.</AbstractText>To assess the prevalence and clinical significance of electrolyte imbalance in ACS.</AbstractText>Serum potassium and magnesium levels were measured within the first few hours in 204 consecutive patients with ACS admitted to our department over a period of 23 months. Cardiac arrhythmia was documented using continuous ECG monitoring, telemetry or standard ECG.</AbstractText>Hypokalemia was observed in 34% of patients, and was significantly associated with the occurrence of life-threatening ventricular arrhythmias (26% of patients with potassium level <4 mmol/l vs 11.9% of patients with normokalemia, p<0.001). No relationship was found between potassium level and supraventricular arrhythmias or in-hospital mortality. Decreased magnesium serum concentration was found in 22% of patients but was not significantly associated with cardiac arrhythmias or mortality.</AbstractText>Hypokalemia and hypomagnesemia are often present in patients with ACS. The former is associated with dangerous ventricular arrhythmias. Early assessment of electrolyte serum concentration is needed in order to implement proper supplementation.</AbstractText> |
2,011 | Prediction of atrial fibrillation in patients with severe mitral stenosis--role of atrial contribution to ventricular filling. | Atrial contribution to ventricular filling was studied to assess its role in predicting the future development of atrial fibrillation (AF) in patients with severe mitral stenosis (MS) and sinus rhythm.</AbstractText>Two hundred and eight patients with severe MS and sinus rhythm were followed up for 1 year. Baseline data were compared between group I (who developed AF at follow-up) and group II (who maintained sinus rhythm). Left atrial size, severity of MS, velocity time integral (VTI) of mitral valve flow and VTI due to atrial systole (A-VTI) were noted. Percentage contribution of A-VTI to the total VTI (A-%) was calculated. Sensitivity and specificity of A-% to predict the onset of AF was obtained.</AbstractText>Left atrial size, severity of MS and total VTI were similar in the two groups. Group I patients were older (31.1 +/- 9.1 and 18.4 +/- 6.5 years, respectively, p < 0.03) with smaller A-VTI (5.3 +/- 2.2 and 6.7 +/- 3.4 cm, respectively, p < 0.01) and A-% (8.9 +/- 1.8 and 11.2 +/- 2.7, respectively, p < 0.003). A-% of <9% (mean value of A-VTI in group I) had high sensitivity (84%, positive predictive value 76%) and specificity (80%, negative predictive value 87%) to predict the development of AF.</AbstractText>Atrial contribution to ventricular filling is reduced in patients prone to develop AF (due to inefficient left atrial contraction, much before its dilatation). It can be used for early identification of patients likely to develop AF with high sensitivity and specificity. It is simple, easily available, cost-effective and will guide earlier intervention and more frequent follow-up. There is a preclinical loss in atrial pump function much before the eventual onset of AF.</AbstractText> |
2,012 | [Analysis of ventricular fibrillation signals for the evaluation of defibrillation success in the treatment of ventricular fibrillation]. | Precise detection of ventricular fibrillation (VF), reliable prediction of defibrillation success and adjustment of the discharge waveform to the patient's transthoracic impedance may contribute to a reduction of electricity-associated myocardial injury caused by unnecessary counter shocks. Specifically, asystole thresholds distinguish between VF and asystole, and thus prevent unnecessary defibrillation attempts. We reviewed various studies and manufacturer characteristics regarding the parameters and algorithms for analyzing arrhythmia ECG signals.</AbstractText>Asystole threshold values of several defibrillator manufacturers were collected and a literature review was performed including the following parameters: amplitude, frequency, bispectral analysis, amplitude spectrum area, wavelets, nonlinear dynamics, N(alpha)histograms, and combinations of various parameters.</AbstractText>The manufacturer dependent asystole thresholds vary substantially. We show ways to optimize an ECG-based analysis for the next technological generation of defibrillators. During advanced cardiac life support (ACLS) the probability of defibrillation success should be estimated. Optimal defibrillation waveform, depending on transthoracic resistance, should be individually determined. In case of prolonged VF with a low ECG amplitude defibrillation should not be attempted unless coronary perfusion has been improved by further measures of ACLS. The combined evaluation of VF amplitude and frequency is effective in predicting defibrillation success. Estimation of further parameters is potentially useful for guiding optimal timing of defibrillation. At present, the implementation of most parameters in out-of-hospital cardiopulmonary resuscitation (CPR) is limited by the lack of technical feasibility of online computing.</AbstractText>Analysis of VF ECG signals should allow adequate VF detection as well as prediction of defibrillation success. Suitable asystole thresholds for analysis of ECG signals have to be determined, and the adverse effects of CPR associated artefacts on data analysis have to be reduced. Analysis of VF ECG signals is a precondition of individually optimized defibrillation and may contribute substantially to an increased quality of CPR.</AbstractText> |
2,013 | Female alcoholics: electrocardiographic changes and associated metabolic and electrolytic disorders. | To identify the electrocardiographic changes and their associations with metabolic and electrolytic changes in female alcoholics.</AbstractText>The study comprised 44 female alcoholics with no apparent physical disorder. They underwent the following examinations: conventional electrocardiography; serologic tests for syphilis, Chagas' disease, and hepatitis B and C viruses; urinary pregnancy testing; hematimetric analysis; biochemical measurements of albumin, fibrinogen, fasting and postprandial glycemias, lipids, hepatic enzymes, and markers for tissue necrosis and inflammation.</AbstractText>Some type of electrocardiographic change was identified in 33 (75%) patients. In 17 (38.6%) patients, more than one of the following changes were present: prolonged QTc interval in 24 (54.5%), change in ventricular repolarization in 11(25%), left ventricular hypertrophy in 6 (13.6%), sinus bradycardia in 4 (9.1%), sinus tachycardia in 3 (6.8%), and conduction disorder in 3 (6.8%). The patients had elevated mean serum levels of creatine phosphokinase, aspartate aminotransferases, and gamma glutamyl transferase, as well as hypocalcemia and low levels of total cholesterol and LDL-cholesterol. The patients with altered electrocardiograms had a more elevated age, a lower alcohol consumption, hypopotassemia, and significantly elevated levels of triglycerides, postprandial glucose, sodium and gamma glutamyl transferase than those with normal electrocardiograms. The opposite occurred with fasting glycemia, magnesium, and alanine aminotransferase.</AbstractText>The electrocardiographic changes found were prolonged QTc interval, change in ventricular repolarization, and left ventricular hypertrophy. Patients with normal and abnormal electrocardiograms had different metabolic and electrolytic changes.</AbstractText> |
2,014 | Frequency-dependent effects of low-intensity ultrasound on activity of isolated heart. | The experiments with low-intensity ultrasound stimulation of isolated rat heart revealed frequency-dependent effects of ultrasound in a frequency range of 45-298 kHz on cardiac activity. |
2,015 | Does antegrade blood cardioplegia alone provide adequate myocardial protection in patients with left main stem disease? | The optimum route for cardioplegia administration in patients with severe coronary disease is still under debate. This study compared clinical, echocardiographic, and biochemical results in patients with left main stem disease treated with 2 different strategies of myocardial protection.</AbstractText>Between March 2000 and November 2002, 148 consecutive patients with left main stem disease undergoing coronary artery bypass grafting were divided into 2 groups according to the route of cardioplegia delivery: antegrade in 87 patients (group A) or antegrade followed by retrograde in 61 patients (group B). Electrocardiography, troponin I, MB-creatine kinase, and MB-creatine kinase mass were performed at 12, 24, 48, and 72 hours postoperatively. Echocardiography was performed preoperatively and before hospital discharge. Data were stratified in subgroups of patients with the following associated risk factors: left ventricular hypertrophy, diabetes, and right coronary stenosis.</AbstractText>Groups were homogeneous in preoperative and intraoperative variables, apart from the higher incidence of unstable angina and severity of left main stem disease in group B. Hospital deaths, intensive therapy unit and hospital stay, perioperative acute myocardial infarction, and intraaortic balloon pump support were similar in both groups. Postoperative recovery of left ventricle ejection fraction and wall motion score index did not differ between the 2 groups. However, postoperative atrial fibrillation was higher in group A (P =.015), especially in patients with diabetes (P <.0001). Troponin I was significantly higher in group A from postoperative hours 12 to 72 (P <.01), and the same pattern was observed in patients with diabetes (P <.001), critical right coronary stenosis (P <.001), and left ventricle hypertrophy (P <.001).</AbstractText>The combined route of intermittent blood cardioplegia allows better results in left main stem disease. Such data are confirmed even in risk subgroups.</AbstractText> |
2,016 | Successful catheter ablation of electrical storm after myocardial infarction. | We report on 4 patients (aged 57 to 77 years; 3 men) who developed drug-refractory, repetitive ventricular tachyarrhythmias after acute myocardial infarction (MI). All episodes of ventricular arrhythmias were triggered by monomorphic ventricular premature beats (VPBs) with a right bundle-branch block morphology (RBBB).</AbstractText>Left ventricular (LV) mapping was performed to attempt radiofrequency (RF) ablation of the triggering VPBs. Activation mapping of the clinical VPBs demonstrated the earliest activation in the anteromedial LV in 1 patient and in the inferomedial LV in 2 patients. Short, high-frequency, low-amplitude potentials were recorded that preceded the onset of each extrasystole by a maximum of 126 to 160 ms. At the same site, a Purkinje potential was documented that preceded the onset of the QRS complex by 23 to 26 ms during sinus rhythm. In 1 patient, only pace mapping was attempted to identify areas of interest in the LV. Six to 30 RF applications abolished all local Purkinje potentials at the site of earliest activation and/or perfect pace mapping and suppressed VPBs in all patients. No episode of ventricular tachycardia or fibrillation has recurred for 33, 14, 6, and 5 months in patients 1, 2, 3, and 4, respectively.</AbstractText>Incessant ventricular tachyarrhythmias after MI may be triggered by VPBs. RF ablation of the triggering VPBs is feasible and can prevent drug-resistant electrical storm, even after acute MI. Catheter ablation of the triggering VPBs may be used as a bailout therapy in these patients.</AbstractText> |
2,017 | Plasma B-type natriuretic peptide levels in ambulatory patients with established chronic symptomatic systolic heart failure. | The diagnostic and prognostic values of plasma B-type natriuretic peptide (BNP) testing are established. However, the range of plasma BNP levels present in the setting of chronic, stable systolic heart failure (HF) is unclear.</AbstractText>We followed up 558 consecutive ambulatory patients with chronic, stable systolic HF (left ventricular ejection fraction <50%) treated at a specialized outpatient HF clinic between November 2001 and February 2003. Retrospective chart review was performed to determine clinical and functional data at the time of BNP testing (Biosite Triage). The clinical characteristics of patients with plasma BNP levels <100 pg/mL and those with > or =100 pg/mL were compared. In our cohort, 60 patients were considered asymptomatic, and their plasma BNP levels ranged from 5 to 572 pg/mL (median, 147 pg/mL). Of the remaining 498 symptomatic (NYHA functional class II-III) patients, 106 (21.3%) had plasma BNP levels in the "normal" diagnostic range (<100 pg/mL). Patients in this "normal BNP" subgroup were more likely to be younger, to be female, to have nonischemic pathogenesis, and to have better-preserved cardiac and renal function and less likely to have atrial fibrillation.</AbstractText>In the ambulatory care setting, both symptomatic and asymptomatic patients with chronic, stable systolic HF may present with a wide range of plasma BNP levels. In a subset of symptomatic patients (up to 21% in our cohort), plasma BNP levels are below what would be considered "diagnostic" (<100 pg/mL).</AbstractText> |
2,018 | Carvedilol alone or in combination with digoxin for the management of atrial fibrillation in patients with heart failure? | This study examined the relative merits of digoxin, carvedilol, and their combination for the management of patients with atrial fibrillation (AF) and heart failure (HF).</AbstractText>In patients with AF and HF, both digoxin and beta-blockers reduce the ventricular rate, and both may improve symptoms, but only beta-blockers have been shown to improve prognosis. If combined therapy is not superior to beta-blockers alone, treatment of patients with HF and AF could be simplified by stopping digoxin.</AbstractText>We enrolled 47 patients (29 males; mean age 68 years) with persistent AF and HF (mean left ventricular ejection fraction [LVEF] 24%) in a randomized, double-blinded, placebo-controlled study. In the first phase of the study, digoxin was compared with the combination of digoxin and carvedilol (four months). In the second phase, digoxin was withdrawn in a double-blinded manner in the carvedilol-treated arm, thus allowing a comparison between digoxin and carvedilol (six months). Investigations were undertaken at baseline and at the end of each phase.</AbstractText>Compared with digoxin alone, combination therapy lowered the ventricular rate on 24-h ambulatory electrocardiographic monitoring (p < 0.0001) and during submaximal exercise (p < 0.05), whereas LVEF (p < 0.05) and symptom score (p < 0.05) improved. In phase 2, there was no significant difference between digoxin alone and carvedilol alone in any variable. The mean ventricular rate rose and LVEF fell when patients switched from combination therapy to carvedilol alone. Six-minute walk distance was not significantly influenced by any therapy.</AbstractText>The combination of carvedilol and digoxin appears generally superior to either carvedilol or digoxin alone in the management of AF in patients with HF.</AbstractText> |
2,019 | Ventricular fibrillation during anesthesia in association with J waves in the left precordial leads in a child with coarctation of the aorta. | A 14-year-old boy with coarctation of the aorta who showed repeat ventricular fibrillation during anesthesia, and ultimately sudden cardiac death in school, is presented. Electrocardiography showed J waves in the left precordial leads, which became prominent after an episode of ventricular fibrillation. While some of the clinical features and electrophysiological findings were similar to those seen in Brugada syndrome, others were inconsistent. J waves in the left precordial leads should be recognized as a possible waveform change inducing ventricular fibrillation predominantly at rest. |
2,020 | Comparison of P-wave duration and dispersion in patients aged > or =65 years with those aged < or =45 years. | P-wave dispersion (PWD) is a new electrocardiographic marker that reflects discontinuous and inhomogeneous propagation of sinus impulses, which has been studied in some cardiac conditions as a useful predictor of paroxysmal atrial fibrillation (AF). The aim of the peresent study was to compare P-wave duration and PWD in patients < or =45 versus > or =65 years of age. The study consisted of 2 groups. Group I included 118 patients aged > or =65 years (86 men, 32 women, mean age= 69 +/- 4 years). Group II included 72 patients aged < or =45 years (53 men, 19 women, mean age= 41 +/- 4 years). All patients were selected from those who were undertaken coronary angiography in our hospital with a suspicion of coronary artery disease and detected as having angiographically normal coronary arteries. All patients were undertaken transthoracic echocardiography to evaluate the presence of any structural and functional cardiac abnormality. Maximum and minimum P-wave durations and PWD were calculated from 12-lead surface electrocardiogram. Maximum P-wave duration and PWD were significantly higher in group I patients than in group II patients (P <.001). However, there was no statistically significant difference between group I patients and group II patients regarding minimum P-wave duration (p=0.9). Left atrial diameter, left ventricular wall thicknesses, mitral A velocity, deceleration time and isovolumic relaxation time were significantly higher in group I patients than in group II patients. However, mitral E velocity were significantly lower in group I patients than in group II patients. A significant positive correlation was detected between PWD and age, left atrial diameter, mitral A velocity, deceleration time and isovolumic relaxation time. In addition, we found a significant negative correlation between PWD and mitral E velocity. PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients > or =65 years of age than in those < or =45 years of age. Further prospective studies that include larger series and long term follow-up are needed to clarify the clinical utility of PWD as a predictor of increased risk for paroxysmal AF in old patients. |
2,021 | Electrophysiologic effects of mental stress in healthy subjects: a comparison with epinephrine infusion. | Mental stress has been associated with serious cardiac arrhythmias, including ventricular tachycardia and ventricular fibrillation. The purpose of this study was to assess cardiac electrophysiologic effects of mental stress and compare them with those of epinephrine infusion. Ten healthy male volunteers participated. Electrophysiologic and hemodynamic variables were measured at baseline, during mental stress produced by Stroop's color word conflict test and during epinephrine infusion at 2 rates (0.025 micromol/kg/min and 0.3 micromol/kg/min). Mental stress produced significant effects on the electrophysiologic properties of the heart with shortening of all measured electrophysiologic variables except atrial, most markedly those of the sinus and the atrioventricular nodes. The effects on the right ventricular myocardium and the His-Purkinje conduction system were less pronounced. During infusion of epinephrine, corresponding effects could only be reproduced at a much higher plasma level. Circulating epinephrine apparently plays a minor role as a mediator of mental stress effects on the heart. |
2,022 | Annual distribution of ventricular tachycardias and ventricular fibrillation. | Ischemic events and coronary deaths show seasonal variability with a peak during December and January. It remains unclear whether ventricular tachycardias (VT) and ventricular fibrillation (VF) follow a similar pattern. The purpose of this study was to investigate the annual distribution of malignant ventricular arrhythmias.</AbstractText>Over a period of 11 years, all appropriate shock episodes (SE) after VT and VF in patients with an implantable cardioverter defibrillator (lCD) were analyzed with respect to the month of occurrence. An appropriate SE was defined as out-of-hospital VT/VF terminated by lCD shocks. Multiple shocks within 1 week were defined as 1 SE.</AbstractText>Two hundred and thirty-three of 308 patients with an lCD had appropriate SE during follow-up. In these patients the seasonal variation of 753 SE was calculated. Most SE occurred during January (93 SE), and the fewest SE occurred during June (39 SE). The seasonal pattern was statistically significant with a peak during winter (P =.001). The seasonal pattern did not differ between patients with an ischemic and those with a nonischemic underlying cardiac disease.</AbstractText>Appropriate shock episodes due to out-of-hospital VT/VF in patients with an lCD show seasonal variation with a significant peak during winter. The pattern is similar in patients with ischemic and nonischemic cardiac disease.</AbstractText> |
2,023 | Acute pulmonary edema after cardioversion of cardiac arrhythmias. | To examine the occurrence of acute pulmonary edema after cardioversion of arrhythmias.</AbstractText>Cases, case series, and related articles on the subject identified through a comprehensive literature search were examined.</AbstractText>Thirty cases (23 males) of post cardioversion acute pulmonary edema were identified. The mean age was 53.8 +/- 13 years (range, 18 to 75 years). Underlying arrhythmias were atrial fibrillation (69%), atrial flutter (24%), supraventricular tachycardia (4%), and ventricular tachycardia (4%). The duration of arrhythmia preceding cardioversion varied widely ranging from 1 day to 13 years. Twenty-six (87%) patients had concomitant cardiovascular disease comprising of coronary artery disease (38%), rheumatic heart disease (23%), cardiomyopathy (23%), and hypertension (8%). Direct current electrical cardioversion was used in 28 (93%) patients and pacing in two (7%) patients. Occurrence of pulmonary edema was independent of the amount of energy used for cardioversion (range 20 to 1280 Joules, mean 263 +/- 27 Joules). Short acting general anesthetic drugs were administered in 14 (47%) and sedation in eight (27%) patients. Sinus rhythm was established in 23 (77%) patients. Duration to develop pulmonary edema after cardioversion was available in 23 patients and ranged from immediately to 96 h. Pulmonary edema occurred within 15 min after cardioversion in 22%, within 3 h in 30%, within 24 h in 30%, within 48 h in 17% and within 96 h in remaining 4% of patients. Three patients required mechanical ventilation.</AbstractText>The rare complication of acute pulmonary edema after cardioversion has been reported mostly in patients with underlying cardiac disease, and is independent of the amount of energy used for cardioversion.</AbstractText> |
2,024 | Electrophysiological effects accompanying regression of left ventricular hypertrophy. | The aim of this study was to investigate changes following regression of left ventricular hypertrophy (LVH).</AbstractText>Electrophysiolological changes were recorded in isolated guinea-pig myocardial preparations. LVH was induced by constriction of the thoracic aorta and regression was followed after removal of the constriction. Sham-operated animals served as controls.</AbstractText>During 42 days constriction, heart/body weight ratio increased (3.19+/-0.49 vs. 3.85+/-0.83 g kg(-1)) and was accompanied by an increase of cell size. Forty-two days after clip removal, values had returned to control values. LVH increased action potential (AP) duration (mean 112% of control) and decreased conduction velocity (60.4+/-3.3 vs. 45.9+/-4.6 cm(-1)). These changes did not return to control after regression of LVH. The changes to condition velocity were attributed solely to increases of intracellular resistivity. The positive staircase response also decreased with LVH, but did recover upon regression. In isolated whole hearts, no changes to subepicardial action potential duration, QRS complex duration or AP refractory period were observed in LVH or its regression. During low-flow ischaemia AP duration shortened reversibly, the rate of shortening was more rapid in hypertrophied hearts but similar to control in regressed hearts. The incidence of ventricular tachyarrhythmias of fibrillation during low-flow ischaemia was similar in control, hypertrophied and regressed hearts.</AbstractText>Morphological regression of LVH is not accompanied by reversal of electrophysiological changes measured in isolated preparations, whereas some aspects of contractile function to recover.</AbstractText> |
2,025 | Compared to angiotensin II, epinephrine is associated with high myocardial blood flow following return of spontaneous circulation after cardiac arrest. | Epinephrine (adrenaline) and vasopressin are used currently to improve myocardial blood flow (MBF) during cardiac arrest. Angiotensin II has also been shown to improve MBF during CPR. We explored the effects of angiotensin II or epinephrine alone, and the combination of angiotensin with epinephrine, on myocardial and cerebral blood flows in a swine model of cardiac arrest.</AbstractText>Swine were instrumented for regional blood flow measurements. Ventricular fibrillation was induced and CPR begun. Angiotensin II 50 mcg/kg (ANG), epinephrine 0.02 mg/kg (EPI) or the combination (ANG+EPI) was administered. Blood flow was measured during baseline normal sinus rhythm (NSR), before (CPR) and after drug administration (CPR+DRUG), and post reperfusion return of spontaneous circulation (ROSC).</AbstractText>All groups had a significant increase in MBF during CPR following drug administration (P<0.05). [table: see text] There was a trend toward higher flows in the EPI groups. The group receiving both EPI and ANG did not have higher blood flows than the EPI or ANG alone groups. Both groups that received EPI had markedly elevated MBF following ROSC compared with angiotensin II (P<0.05).</AbstractText>The combination of ANG and EPI did not improve MBF during cardiac arrest. Epinephrine may increase MBF compared with angiotensin II post-reperfusion.</AbstractText> |
2,026 | Comparison of standard CPR versus diffuse and stacked hand position interposed abdominal compression-CPR in a swine model. | Interposed abdominal compression cardiopulmonary resuscitation (IAC-CPR) is an innovative basic life support technique requiring no mechanical adjuncts. Optimizing its performance remains a challenge. Hand-position technique over the abdomen during interposed abdominal compression (IAC) may be important. The purpose of this study was to determine if there is a difference in efficacy depending on the type of abdominal hand-position used. Two different hand positions were studied: open hands, placed side by side, resulting in diffuse abdominal compression and stacked hands, with one on top of the other, producing a more focal compression of the abdomen. Thirty swine were cannulated with micromanometer-tipped pressure transducers in the ascending aorta (Ao) and right atrium (RA), and Millar Doppler-tipped catheters in the descending aorta and inferior vena cava (IVC) to determine flow patterns during cardiopulmonary resuscitation (CPR), During CPR there were no differences in aortic systolic or right atrial systolic pressures. Both forms of IAC-CPR produced greater aortic diastolic and right atrial diastolic pressures then standard CPR (STD-CPR) (P<0.05). Coronary perfusion pressures (CPP), however, were not different. Blood flow directions and velocity patterns showed that STD-CPR chest compressions produce caudally directed blood flow in both the descending aorta and the IVC, and that such flows reverse (becoming cranially directed) during the relaxation phase of chest compression. IAC-CPR produced similar blood flow patterns in the aorta and IVC, as seen with STD-CPR. There were no differences in blood flow patterns between the different forms of IAC-CPR. No CPR-produced trauma difference was found. Abdominal hand position (diffuse or stacked) did not affect blood flow in either the aorta or IVC or resuscitation success in this experimental model. There was a trend towards better outcomes with stacked hands IAC-CPR with 90 versus 70% survival with STD-CPR. |
2,027 | Incidence and survival rate of bystander-witnessed out-of-hospital cardiac arrest with cardiac etiology in Osaka, Japan: a population-based study according to the Utstein style. | To clarify the incidence and survival rate of bystander-witnessed out-of-hospital cardiac arrests (OHCA) with cardiac etiology in Osaka Prefecture, Japan, with a population of nearly 9 million according to the Utstein style.</AbstractText>5047 consecutive OHCA cases were treated by ambulance personnel during the 12-month period starting since 1 May 1998. 974 cases were considered to be bystander-witnessed OHCA with cardiac etiology and analyzed using the Utstein style.</AbstractText>Of the 974 cases (100%), 50 cases (5.1%) survived after 1 month and 28 (2.9%) of them after 1 year. The Ventricular fibrillation (VF)/ventricular tachycardia (VT) group comprised 164 (16.8%) cases and there were statistically differences between the two groups as below (the VF/VT group vs. the non-VF/VT group): gender (male: 76.8 vs. 60.7%), age (61.7+/-14.7 vs. 68.7+/-17.1), history of ischemic heart disease (IHD) (30.5 vs. 15.3%), performance rate of bystander cardiopulmonary resuscitation (CPR) (34.1 vs. 21.4%) and time interval between receipt of an emergency call and arrival at the scene (5.5+/-2.9 vs. 6.0+/-2.9 min).</AbstractText>The incidence of bystander-witnessed (OHCA) with cardiac etiology and VF or VT were remarkably low compared with those reported by other studies conducted in some areas of Europe or the USA.</AbstractText> |
2,028 | A multiple logistic regression analysis of in-hospital factors related to survival at six months in patients resuscitated from out-of-hospital ventricular fibrillation. | The impact of the immediate in-hospital post-resuscitation care after out-hospital cardiac arrest is not well known. Based on treatment variables and laboratory findings a multiple logistic regression model was created for the prediction of survival at 6 months from the event.</AbstractText>A retrospective study of the hospital charts of patients successfully resuscitated and treated in one of three community hospitals from 1998 to 2000. In addition to several pre-hospital variables, the mean 72 h values of clinical features such as blood pressure, blood glucose concentration and initiated treatment used, were included in a forward multiple logistic regression model predicting survival at 6 months from the event.</AbstractText>The charts of 98 out of a total of 102 patients were sufficiently complete and included in the analysis. Variables independently associated with survival were age, delay before a return of spontaneous circulation, mean blood glucose and serum potassium, and the use of beta-blocking agents during post-resuscitation care. When those patients who were assigned a 'do not attempt to resuscitate' (DNAR) order during the first 72 h of treatment were excluded from the analysis blood glucose, blood potassium and the use beta-blocking agents remained independently associated with survival.</AbstractText>This study suggests that in-hospital factors are associated with survival from out-of-hospital cardiac arrest. The mean blood glucose and serum potassium during the first 72 h of treatment and the use of beta-blocking agents were significantly and independently associated with survival.</AbstractText> |
2,029 | The Quattro valve in rheumatic mitral valve disease: four-year follow up. | There remains a great need for bioprosthetic valves in developing countries where monitoring of anticoagulation therapy is difficult. The study aim was to assess the intermediate outcome following mitral valve replacement with a stentless bovine pericardial quadrileaflet mitral (Quattro) valve. This valve maintains mitral annular-papillary continuity in patients with isolated severe rheumatic mitral valve disease.</AbstractText>Since December 1996, the Quattro valve has been implanted in 47 patients (mean age 34 +/- 13 years; 16 (34%) aged <25 years) with rheumatic mitral valve disease. All patients were symptomatic, and in NYHA class II (n = 7), III (n = 30) or IV (n = 10). Preoperatively, all patients underwent full clinical and routine echocardiographic assessment, as well as intraoperative transesophageal evaluation after valve implantation. At follow up visits, clinical and echocardiographic evaluations were carried out in each patient.</AbstractText>After a mean follow up of 51 +/- 11 months, the overall mortality was 10.6% (five deaths). Five patients did not return for clinical follow up, but three of these are known to be alive and well. Of the 37 patients who returned for regular follow up, 32 remained symptomatically improved. Valve explantation was performed in two patients (4.2%) for prosthetic valve endocarditis. Two patients have deteriorated as a result of left ventricular dysfunction, and one patient has developed severe mitral regurgitation. Thromboembolism or clinically overt hemolysis has not occurred. One patient, who was receiving coumadin therapy for atrial fibrillation, died following a massive hematemesis. Serial one-year echocardiography data at one, two and three-year follow up intervals were available in 28 patients. These data confirmed no significant change in valve area or in mean diastolic gradient. Varying degrees of valve thickening were detected echocardiographically in 10 patients; four patients had clinically significant mitral stenosis (valve area <1.5 cm2). One valve was explanted for structural deterioration.</AbstractText>Intermediate results after Quattro valve implantation in a relatively young population were satisfactory. However, long-term follow up is mandatory to assess valve durability.</AbstractText> |
2,030 | [Brugada syndrome associated with ventricular fibrillation induced by administration of pilsicainide: a case report]. | A 56-year-old man with Brugada syndrome presented with ventricular fibrillation induced by administration of pilsicainide. He had syncope at age 46 years, and his uncle suddenly died of unknown cause. He had taken pilsicainide (150 mg/day) for paroxysmal atrial fibrillation, and suffered from syncope due to ventricular fibrillation. Coved type ST elevation was observed in the V1 lead, and saddle back type ST elevation was observed in the V2 lead. The ST elevation gradually recovered after stopping pilsicainide therapy. No structural heart disease was found. After intravenous injection of pilsicainide, the ST segment elevated in the V1 and V2 leads. Ventricular fibrillation was induced by triple extrastimulation at the right ventricular apex. The diagnosis was Brugada syndrome, and a cardioverter-defibrillator was implanted. Brugada syndrome should be considered before administering pilsicainide. |
2,031 | Catheter ablation of ventricular fibrillation in rabbit ventricles treated with beta-blockers. | A therapeutic implication of the focal-source hypothesis of ventricular fibrillation (VF) is that VF can be terminated by focal ablation. We hypothesize that beta-adrenergic receptor blockade converts multiple-wavelet VF to focal-source VF and that this focal source is located near the papillary muscle (PM).</AbstractText>We used optical mapping techniques to study the effects of propranolol (0.3 mg/L) on VF dynamics in Langendorff-perfused rabbit hearts. The left ventricular (LV) anterior wall was mapped and optical action potential duration restitution (APDR) was determined at 25 epicardial sites. We performed ablation during VF of the left anterior PM in hearts with (N=6) or without (N=6) cytochalasin infusion, the LV lateral epicardium (Epi group, N=3), and the LV endocardium (Endo group, N=3). The PM was also ablated in 3 hearts without propranolol (control group). Propranolol converted multiple-wavelet VF to slow VF with reentry localized to the PM. Propranolol decreased the maximal slope of the APDR curve (P<0.001) as well as its spatial heterogeneity (P<0.01) and conduction velocity (P=0.01) while increasing the VF cycle length (P<0.001). PM ablation terminated VF during propropranolol infusion with (6 of 6, 100%) or without (4 of 6, 67%) cytochalasin D and significantly reduced inducibility. VF did not terminate in the Epi, Endo, and control groups (P<0.001).</AbstractText>Propranolol flattens the APDR curve and reduces conduction velocity, converting multiple-wavelet VF into VF with a focal source anchored to the PM. Ablation of this focal source may terminate VF.</AbstractText> |
2,032 | Use of automated external defibrillator by first responders in out of hospital cardiac arrest: prospective controlled trial. | To test the hypothesis that the use of an automated external defibrillator by police and fire fighters results in higher discharge rates for out of hospital cardiac arrest.</AbstractText>Controlled clinical trial with initial random allocation of automated external defibrillators to first responders in four of the eight participating regions; each region switched from control to experimental, and vice versa, every four months.</AbstractText>Amsterdam and surroundings, the Netherlands.</AbstractText>Patients with witnessed out of hospital cardiac arrests, identified by the emergency medical system between January 2000 and January 2002.</AbstractText>Survival to hospital discharge; return of spontaneous circulation; admission to hospital.</AbstractText>243 patients (65% in ventricular fibrillation) were included in the experimental area and 226 patients (67% in ventricular fibrillation) in the control area. The median time interval between collapse and first shock was 668 seconds in the experimental area and 769 seconds in the control area (P < 0.001). 44 (18%) patients in the experimental area versus 33 (15%) patients in the control area were discharged (odds ratio 1.3 (95% confidence interval 0.8 to 2.2), P = 0.33), 139 (57%) experimental versus 108 (48%) control patients had return of spontaneous circulation (1.5 (1.0 to 2.2), P = 0.05), and 103 (42%) experimental versus 74 (33%) control patients were admitted (1.5 (1.1 to 1.6), P = 0.02). The median delay from receipt of call to dispatch of the ambulance was 120 seconds, and the delay to dispatch of the first responder was 180 seconds.</AbstractText>Use of automated external defibrillators by first responders did not significantly increase survival to discharge from hospital, although it did improve return of spontaneous circulation and admission to hospital. Improved dispatch procedures should increase the success of programmes of first responders using external defibrillators.</AbstractText> |
2,033 | Impact of prophylactic i.v. magnesium on the efficacy of ibutilide for conversion of atrial fibrillation or flutter. | The impact of prophylactic i.v. magnesium on the efficacy of ibutilide for conversion of atrial fibrillation and flutter to normal sinus rhythm was studied. In this multicenter cohort study, all patients in three large, tertiary care centers who received ibutilide for acute chemical conversion of atrial fibrillation or flutter from August 1996 through December 2001 were identified through pharmacy or billing records. Patients who did not receive magnesium before or during ibutilide therapy served as the control group, while those who received magnesium less than two hours before or during ibutilide administration served as the study group. The rate of administration of direct-current cardioversion (DCC) and the occurrence of ventricular arrhythmia were compared between those who did and did not receive magnesium. The rates of successful cardioversion were also assessed. Categorical data were analyzed using chi-square analysis or Fisher's exact test. Demographic data were analyzed using Student's t test. The medical records of 321 patients were analyzed. Successful chemical cardioversion in the study group was approximately 19% higher than in those who did not receive magnesium (p = 0.040). The use of DCC in the group who received magnesium was reduced by approximately 34% (p = 0.045). The conversion rate of atrial fibrillation or flutter with ibutilide was enhanced by magnesium administration (p = 0.040), and the rate of administration of DCC was reduced (p = 0.045) in patients who received magnesium. There was a nonsignificant reduction in the occurrence of ventricular arrhythmias (p = 0.533). The efficacy of ibutilide was enhanced by concomitant administration with intravenous magnesium. |
2,034 | CVT-510: a selective A1 adenosine receptor agonist. | Adenosine is an endogenous nucleoside that has potent antiarrhythmic effects on paroxysmal supraventricular tachycardia (PSVT) due to its negative dromotropic effects on the atrioventricular node. In addition to its electrophysiologic effects, adenosine has important effects on vascular smooth muscle cells, inflammatory cells, the central nervous system, and the kidney. Four known adenosine receptor subtypes (A1, A2A, A2B, and A3) mediate the pleiotropic effects of adenosine in humans. These receptors are coupled to a wide range of second messenger cascades. Activation of the A1 adenosine receptor accounts for the negative chronotropic and dromotropic effects of adenosine, whereas A2A, A2B and A3 adenosine receptor activation are responsible for such effects as coronary vasodilation, bronchospasm, inhibition of platelet aggregation, and neuronal stimulation. Elucidation of the specific properties of each of the adenosine receptor subtypes has led to the development of selective ligands as potential therapeutic agents. CVT-510, N-(3(R)-tetrahydrofuranyl)-6-aminopurine riboside, was developed as a selective A1 adenosine receptor agonist that specifically targets the atrioventricular node for termination of PSVT. Preliminary clinical trials have shown that CVT-510 is effective in terminating PSVT and eliminating many of the undesirable adverse effects of adenosine. CVT-510 is also being explored as a potential agent for controlling the ventricular rate of atrial fibrillation and flutter. |
2,035 | [Sudden cardiac death by commotio cordis]. | Commotio cordis due to blunt trauma to the precordium is a rare cause of death in young athletes, occurring less frequently than all of the other athletics-related deaths. Commotio cordis is a term used to describe cases of blunt thoracic impact causing fatality without structural damage of the heart and internal organs. Death is attributed to ventricular fibrillation, which is often resistant to resuscitative therapy. In this article we discussed this catastrophic event, its historical development, epidemiology and clinical presentation, mechanisms for sudden death in commotio cordis, limitations of evidence using animal models, autopsy findings, resuscitation and preventive measures. |
2,036 | Acute contrast reaction management by radiologists: a local audit study. | Consultant radiologists and trainees must possess knowledge of optimal acute management of anaphylactic/anaphylactoid contrast reactions because patient survival depends upon prompt initial management. The aim of the present study is to assess the knowledge of first-line management of these reactions among radiologists. Within one working day, and without prior knowledge, radiology consultants and trainees within four teaching hospitals in a major Australian capital city were asked to complete a confidential questionnaire regarding acute resuscitation management. Scenarios were presented of an adult who developed life-threatening symptoms of anaphylaxis immediately after intravenous contrast administration, ventricular fibrillation and profound bradycardia. Questions were asked with regards to adrenaline, corticosteroid, antihistamines, intravenous volume expansion, cardio-pulmonary rescuscitation and knowledge of the emergency telephone number. Sites were assessed for presence of an anaphylaxis management chart and also when each participant last completed a resuscitation course. Forty-two participants were recruited. Overall, 53% of questions were answered correctly. Only 43% knew the adrenaline dose and if an incorrect dose was administered it was more likely to be an overdose. Notable inadequacies were also discovered with corticosteroid, atropine, antihistamine doses and intravenous fluid use. Only 26% had completed a resuscitation course in the past 2 years. Forty-five percent knew the emergency telephone number and 55% of rooms using intravenous contrast contained an immediately visible chart for contrast reaction management. Radiologist and trainee knowledge of immediate life-threatening contrast reaction management is deficient. Severe contrast reactions are uncommon with today's use of non-ionic contrast, but they still occur. Experience in the management of anaphylaxis can only come from regular, compulsory training. |
2,037 | Ion channel basis for alternans and memory in cardiac myocytes. | Beat-to-beat alternation in action potential morphology (alternans) in individual cardiac cells may be important in the development of ventricular tachycardia and fibrillation. So far, it has been difficult to identify the cause for alternans at the ion channel level because computer models and experiments that display alternans also simultaneously exhibit other confounding rhythm patterns, including those attributable to short timescale memory effects. To address this difficulty, we have developed an eigenmode method to study the dynamics of detailed cardiac cell models under constant pacing. The method completely separates these effects from one another in the linear regime, allowing each to be studied individually. For the Beeler-Reuter ion channel model, the fundamental difference between the alternans and memory modes was found to be rooted in the difference in the relative phasings of the x1 and f gate perturbations associated with the slow outward and slow inward currents, respectively. The importance of this relative phasing was analyzed with the help of two new analytical methods. For the alternans case, the relative phasing produced constructive interference between the two currents large enough to reverse the perturbation in membrane potential from beat to beat. The opposite was true of the memory mode. |
2,038 | [Atrial fibrillation: therapeutic strategies]. | Atrial fibrillation is the most common tachyarrhythmia encountered in clinical practice. Atrial fibrillation is associated with other cardiovascular diseases and advancing age. Patients with atrial fibrillation suffer significantly higher morbidity and morality rates, leading to more hospitalizations and higher health costs. Treatment strategies for atrial fibrillation vary widely among clinicians. Two basic strategies are available, control of the ventricular rate with anticoagulation, and restoration and maintenance of sinus rhythm. It courts individualization of therapy in dependence on clinical situation and considering potential advantages and risk. |
2,039 | Ventricular fibrillation and rhabdomyolysis after administration of succinylcholine. | Succinylcholine is a depolarising muscle relaxant. Because of its quick onset of action, it is particularly used in situations which require urgent intubation. However, there have been several reports of cardiac arrest after administration of succinylcholine. We describe the case of a young woman who developed ventricular fibrillation and rhabdomyolysis following succinylcholine administration. Possible mechanisms and treatment are discussed. |
2,040 | Milrinone facilitates resuscitation from cardiac arrest and attenuates postresuscitation myocardial dysfunction. | Left ventricular (LV) dysfunction with a low cardiac index after successful CPR contributes to early death attributable to multiorgan failure, and an effective treatment has not been identified. The purpose of this study was to investigate the use of milrinone, a selective phosphodiesterase III inhibitor, as treatment for LV dysfunction after resuscitation.</AbstractText>Ventricular fibrillation (VF) was induced electrically in 32 swine. After 5 minutes of VF, CPR was initiated and animals were randomized to receive either saline (control group, n=16) as a bolus and infusion or milrinone 50 microg/kg as a bolus and then 0.5 microg/kg per min for 60 minutes (treatment group, n=16). After 2 minutes of CPR (total VF time, 7 minutes), countershocks were given. Coronary perfusion pressures during CPR were similar for the groups (24+/-2 versus 21+/-4 mm Hg). All animals were defibrillated; 6 of 16 control animals developed refractory postcountershock pulseless electrical activity compared with 0 of 16 treated animals (P=0.018). At 30 minutes after restoration of spontaneous circulation, stroke volume (16+/-3 versus 26+/-7 mL, P<0.01) and LV dp/dt (793+/-197 versus 1108+/-316 mm Hg/s, P<0.02) were higher in the treatment group. Similar differences were observed 60 minutes after restoration of spontaneous circulation. Significant differences in heart rates between groups were not observed, and peripheral vascular resistance was significantly greater in the control group 30 and 60 minutes after resuscitation.</AbstractText>Milrinone facilitates resuscitation from prolonged VF and attenuates LV dysfunction after resuscitation without worsening major determinants of myocardial oxygen demand.</AbstractText> |
2,041 | Implantable cardioverter-defibrillator therapy for prevention of sudden death in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia. | Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a condition associated with the risk of sudden death (SD).</AbstractText>We conducted a multicenter study of the impact of the implantable cardioverter-defibrillator (ICD) for prevention of SD in 132 patients (93 males and 39 females, age 40+/-15 years) with ARVC/D. Implant indications were a history of cardiac arrest in 13 patients (10%), sustained ventricular tachycardia in 82 (62%), syncope in 21 (16%), and other in 16 (12%). During a mean follow-up of 39+/-25 months, 64 patients (48%) had appropriate ICD interventions, 21 (16%) had inappropriate interventions, and 19 (14%) had ICD-related complications. Fifty-three (83%) of the 64 patients with appropriate interventions received antiarrhythmic drug therapy at the time of first ICD discharge. Programmed ventricular stimulation was of limited value in identifying patients at risk of tachyarrhythmias during the follow-up (positive predictive value 49%, negative predictive value 54%). Four patients (3%) died, and 32 (24%) experienced ventricular fibrillation/flutter that in all likelihood would have been fatal in the absence of the device. At 36 months, the actual patient survival rate was 96% compared with the ventricular fibrillation/flutter-free survival rate of 72% (P<0.001). Patients who received implants because of ventricular tachycardia without hemodynamic compromise had a significantly lower incidence of ventricular fibrillation/flutter (log rank=0.01). History of cardiac arrest or ventricular tachycardia with hemodynamic compromise, younger age, and left ventricular involvement were independent predictors of ventricular fibrillation/flutter.</AbstractText>In patients with ARVC/D, ICD therapy provided life-saving protection by effectively terminating life-threatening ventricular arrhythmias. Patients who were prone to ventricular fibrillation/flutter could be identified on the basis of clinical presentation, irrespective of programmed ventricular stimulation outcome.</AbstractText> |
2,042 | Impact of a preoperative mitral regurgitation scoring system on outcome of surgical repair for mitral valve prolapse. | The optimal timing of surgical correction of severe mitral regurgitation (MR) is important for improved morbidity and mortality. We utilized a scoring system to decide the timing of procedures. Based on clinical features and echocardiographic data, we hypothesized that preoperative semi-quantitation of MR using this scoring system may be useful for predicting prognosis after repair. The MR score was composed of 6 parameters associated with disease severity (i.e., history of heart failure, atrial fibrillation, pulmonary hypertension, left ventricular end-systolic dimension, fractional shortening, and left atrial dimension). The maximum score was 6. Of 267 patients who underwent mitral valve repair in the last 10 years, 191 patients with mitral valve prolapse were studied. Patients were categorized into 2 groups according to MR score (group low [L] : 0 to 2.5 and group high [H]: >/=3.0) irrespective of New York Heart Association functional class. A significant difference in postoperative event-free survival was observed between both groups (p = 0.0014); the adjusted risk ratio was 3.4 (95% confidence interval 1.6 to 7.2). Postoperative echocardiography showed larger left ventricular systolic dimensions (p <0.0001), lower fractional shortening (p = 0.0016), and larger left atrial dimensions (p <0.0001) in group H than group L. Thus, an MR score is a simple way to predict the prognosis of severe MR independently of subjective symptoms in patients undergoing mitral valve repair. |
2,043 | Acute atrial fibrillation during dengue hemorrhagic fever. | Dengue fever is a viral infection transmitted by the mosquito, Aedes aegypti. Cardiac rhythm disorders, such as atrioventricular blocks and ventricular ectopic beats, appear during infection and are attributed to viral myocarditis. However, supraventricular arrhythmias have not been reported. We present a case of acute atrial fibrillation, with a rapid ventricular rate, successfully treated with intravenous amiodarone, in a 62-year-old man with dengue hemorrhagic fever, who had no structural heart disease. |
2,044 | [Cardiac arrest in severe acute respiratory syndrome: analysis of 15 cases]. | To investigate the causes for cardiac arrest in severe acute respiratory syndrome (SARS) patients.</AbstractText>Retrospective analysis of the epidemiological history, clinical presentation, the change of laboratory tests, chest radiography, and treatment of 15 SARS patients with cardiac arrest.</AbstractText>The average age of the patients was 60 years. Eight had a history of exposure to SARS patients, among them 6 were household contacts. Eight patients had no underlying diseases, and another 8 complained of extreme anxiety. Abnormalities of cardiac enzymes were present in 10 patients. Myocardial ischemia and arrhythmia were present in 5 patients. Bilateral, multifocal lung infiltrates were present in 13 of the 15 patients. Four patients died after defecation and 9 died during relatively stable periods.</AbstractText>It was suggested that the causes for cardiac arrest in SARS patients may include: (1) the lung injury caused by the SARS virus leads to hypoxemia and thus an unsteady state of the myocardial electricity; (2) SARS virus directly causes injury to the myocardial cells and/or the conduct system; (3) SARS infection aggravates the original myocardial pathological change, worsening the conduct block; (4) extreme anxiety leads to extra secretion of catecholamine, which causes instability of myocardial electricity; (5) defecation worsens hypoxemia, which induces arrhythmia (ventricular fibrillation) and causes cardiac arrest.</AbstractText> |
2,045 | Arrhythmogenic right ventricular dysplasia in the elderly. | Arrhythmogenic right ventricular dysplasia (ARVD) is a form of cardiomyopathy characterized by fibrofatty infiltration of the right ventricle that leads to cardiac arrhythmias, usually sustained ventricular tachycardia or ventricular fibrillation. ARVD typically becomes recognized in young adults. The authors report a case of an octogenarian in whom third-degree atrioventricular block, low cardiac output syndrome, and failure to capture the pacer stimuli developed. ARVD was diagnosed at autopsy based on fibrofatty replacement of the right ventricle. To date, this case represents the oldest patient ever diagnosed with ARVD reported in the literature. |
2,046 | Prognostic significance of ventricular arrhythmias post-myocardial infarction. | Despite improvements in management strategies, ventricular arrhythmias remain important markers of electrical instability and contribute to the identification of patients at increased risk of sudden cardiac death post-myocardial infarction (MI). Over the past 20 years, understanding of pathophysiological mechanisms and implications of various types of ventricular arrhythmias has evolved remarkably. This systematic review details the prognostic significance of ventricular arrhythmias classified by type and time of onset post-MI. Subacute and late premature ventricular complexes are associated with increased mortality independent of left ventricular function. Although nonsustained ventricular tachycardia (VT) in the acute phase post-MI is of questionable significance, later onset heralds poorer prognosis. Sustained monomorphic VT in the acute post-MI phase is associated with infarct extension, heart failure and increased mortality. Extensive wall motion abnormalities, left ventricular dysfunction and aneurysm formation correlate with later postinfarct sustained VT. Inhospital mortality is higher when ventricular fibrillation presents in the acute phase but long term prognosis is not adversely affected. |
2,047 | Serum neuron-specific enolase and S-100B protein in cardiac arrest patients treated with hypothermia. | High serum levels of neuron-specific enolase (NSE) and S-100B protein are known to be associated with ischemic brain injury and poor outcome after cardiac arrest. Therapeutic hypothermia has been shown to improve neurological outcome after cardiac arrest. The aim of this study was to evaluate the effect of therapeutic hypothermia on levels of serum NSE and S-100B protein, their time course, and their prognostic value in predicting unfavorable outcome after out-of-hospital cardiac arrest.</AbstractText>Seventy patients resuscitated from ventricular fibrillation were randomly assigned to hypothermia of 33+/-1 degrees C for 24 hours or to normothermia. Serum NSE and S-100B were sampled at 24, 36, and 48 hours after cardiac arrest. Neurological outcome was dichotomized into good or poor at 6 months after cardiac arrest.</AbstractText>The levels of NSE (P=0.007 by analysis of variance for repeated measurements) but not S-100B were lower in hypothermia- than normothermia-treated patients. A decrease in NSE values between 24 and 48 hours was observed in 30 of 34 patients (88%) in the hypothermia group and in 16 of 32 patients (50%) in the normothermia group (P<0.001). The decrease in NSE values was associated with good outcome at 6 months after cardiac arrest (P=0.005), recovery of consciousness (P<0.001), and survival for at least 6 months after cardiac arrest (P=0.012).</AbstractText>Decreasing levels of serum NSE but not S-100B over time may indicate selective attenuation of delayed neuronal death by therapeutic hypothermia in victims of cardiac arrest.</AbstractText> |
2,048 | Rate or rhythm control in persistent atrial fibrillation? | Atrial fibrillation (AF) is the most common sustained tachyarrhythmia encountered in clinical practice, with the majority of patients aged > 65 years. With an increasingly ageing population, the burden of AF in society continues to rise. One of the principal controversies in AF management is whether to control the ventricular rate and accept the underlying rhythm, or to attempt to achieve sinus rhythm. Until recently there were no clinical trial data directly comparing a rate versus rhythm strategy, and most physicians have opted for rhythm control, based on its theoretical benefits. We present an up-to-date evidence-based overview of the relative merits of rate versus rhythm control in AF, including data from five recent randomized trials. We draw conclusions from these studies and present evidence-based guidance on when to adopt which approach in routine clinical practice. |
2,049 | Long electrodes for radio frequency ablation: comparative study of surface versus intramural application. | There is increasing use of radio frequency (RF) ablation with long electrodes in the intraoperative treatment of atrial fibrillation. Nevertheless, the disparity in the lesion geometry in both depth and width is the major pitfall in the use of RF currents. The objective of this study was to differentiate the shape and size of long lesions created by three surface application electrodes (SAE) and two intramural electrodes (IE). The SAE included a standard multi-polar catheter, and two standard electrosurgical pencils. The IE consisted of a needle and a wire both intramurally buried. The lesions were created on fresh fragments of porcine ventricular tissue. The IE created lesions with a curved prism-like shape around the electrode body, with homogeneous characteristics along the lesion trajectory. On the contrary, the lesions created with the SAE were in the shape of an hourglass. They showed a different geometry between the central zone and the edge zone (p<0.001 for depth and surface width). Electrical impedance evolution was recorded during the RF heating. We observed a slow decrease of the impedance in all the electrodes, except in the wire electrode. In conclusion, the results suggest that the IE might be a more suitable option than SAE when it is necessary to create long and homogeneous thermal lesions. |
2,050 | Ruthenium red-induced transition from ventricular fibrillation to tachycardia in isolated rat hearts: possible involvement of changes in mitochondrial calcium uptake. | Ventricular tachycardia (VT) is considered to be the most common precursor of ventricular fibrillation (VF) and sudden cardiac death. However, the mechanisms underlying the transition from VT to VF remain unclear despite more than a century of study. Here, we investigated whether perfusion of the heart with blockers of mitochondrial Ca(2+) uniporter changed the macrodynamics of the heart between VT and VF.</AbstractText>The experiments were performed using Langendorff perfused isolated rat hearts in which left ventricular pressure (LVP) and left ventricular cardiomyogram (LVCMG) were measured. Sustained VT or VF was induced by burst pacing of the left ventricular muscles.</AbstractText>During pacing-induced sustained VF, perfusion of the heart with ruthenium red (RR) or Ru 360, blockers of mitochondrial Ca(2+) uniporter, resulted in the reversible conversion of VF to VT. In contrast, during pacing-induced sustained VT, perfusion of the heart with spermine, an activator of mitochondrial Ca(2+) uptake, resulted in the reversible conversion of VT to VF, and the effect was antagonized by cotreatment with RR. In addition, RR-induced conversion of VF to VT was antagonized by cotreatment with S(-)-Bay K8644 (Bay K), an activator of L-type Ca(2+) channels, suggesting that the inactivation of L-type Ca(2+) channels was responsible for the RR-induced effect on the macrodynamics of hearts. In fact, perfusion with verapamil, an antagonist of L-type Ca(2+) channels, during pacing-induced sustained VF, resulted in the conversion of VF to VT.</AbstractText>This study demonstrated that perfusion of isolated rat hearts with blockers of Ca(2+) uptake by mitochondria resulted in the reversible conversion of pacing-induced sustained VF to VT, suggesting that changes in mitochondrial Ca(2+) uptake were possibly involved in the transition between VT and VF.</AbstractText> |
2,051 | Prospective clinical and biological comparison of three blood cardioplegia techniques in low-risk CABG patients: better is worse than good enough. | Three myocardial protection techniques were evaluated in a prospective, randomised trial during coronary artery bypass grafts in 69 patients.</AbstractText>Twenty seven patients received intermittent hyperkalaemic undiluted warm blood anterograde cardioplegia (AC), 21 received continuous hyperkalaemic undiluted warm blood retrograde cardioplegia (RC) and 21 received intermittent, hyperkalaemic, diluted cold blood (15 degrees C), anterograde cardioplegia (CC). Assessment criteria were clinical, laboratory and haemodynamic.</AbstractText>Groups were homogeneous in terms of age, sex, cardiovascular risk factors, severity of coronary disease, preoperative ejection fraction, and number of bypass grafts performed. The oxygen extraction coefficient, and lactate and troponin production in the coronary sinus on aortic unclamping was not significantly different between the three groups. The base excess was -0.19+/-0.13 in the RC group, -0.18+/-0.52 in the AC group and -2.67+/-0.59 in the CC group (P<0.01 CC vs. AC and CC vs. RC). The priming volume was 1485+/-64 ml (CC), 1317+/-44 ml (RC) and 1318+/-30 ml (AC) (P<0.05 CC vs. AC and CC vs. RC). The haematocrit during CPB was 28.9+/-0.9 (CC), 32.5+/-0.8 (RC) and 32+/-0.7 (AC) (P<0.05 CC vs. AC and CC vs. RC). The volume of crystalloid delivered was 735+/-85 ml (CC), 362+/-67 ml (RC) and 357+/-105 ml (AC) (P<0.05 CC vs. AC and CC vs. RC). The incidence of ventricular fibrillation on aortic unclamping was 61.9% (CC), 9.5% (RC) and 0% (AC) (P<0.01 CC vs. AC and CC vs. RC). The transfusion rate, duration of intubation, postoperative troponin level, complication rate and mortality were not significantly different between the three groups. Haemodynamic parameters at H2, H4, H8 did not vary significantly between the three groups.</AbstractText>These three techniques appear to be comparable in terms of myocardial protection. Anterograde cardioplegia ensures an identical degree of security to retrograde cardioplegia regardless of the coronary lesions, apart from redo lesions. CC requires greater haemodilution of the patients during CPB.</AbstractText> |
2,052 | [Sudden death disclosing abnormal origin of the left coronary vessel from the pulmonary artery trunk]. | Anomalous origin of the left coronary artery from the pulmonary artery is a rare congenital abnormality with a poor prognosis in the newborn. Adult forms are, therefore, very rare, presenting with angina, cardiac failure or sudden death. The authors report the case of a 41 year old woman who was asymptomatic until admitted as an emergency after ventricular fibrillation. Coronary angiography established the diagnosis. Despite the absence of reversible ischaemia on exercise myocardial scintigraphy, the patient underwent coronary bypass surgery of the left anterior descending artery with a pediculated internal mammary artery graft and closure of the left coronary ostium on the pulmonary artery. The echocardiographic abnormalities regressed within a few weeks. An automatic defibrillator was not implanted. The physiopathology of this rare cardiac lesion, the mechanisms of sudden death and the different techniques of surgical repair are discussed. |
2,053 | [PCR-based site-directed mutagenesis and recombinant expression plasmid construction of a SCN5A mutation (K317N) identified in a Chinese family with Brugada syndrome]. | To perform PCR-based site-directed mutagenesis of a new SCN5A mutation (K317N) identified in a Chinese family with Brugada syndrome and construct the recombinant expression plasmid pRc/CMV-Hh1 containing the human cardiac sodium channel alpha subunit (hH1), mutant cDNA.</AbstractText>A pair of primers was designed according to the restricted sites Sse 8387I and Age I of the SCN5A sequence with the mismatches introduced into primers. Mutagenesis was performed in a single-step PCR, and the fragments amplified by PCR containing the mutation site were subcloned into the pRc/CMV-hH1 vector.</AbstractText>Sequence analysis confirmed the presence of the desired mutation site, and a mutation from K (Lys) to N (Asn) in codon 317 was identified in the SCN5A gene, indicating the successful induction of the mutation at K317N of the SCN5A gene.</AbstractText>PCR site-directed mutagenesis is accurate and highly efficient, and the successfully constructed recombinant expression plasmid pRc/CMV-hH1 (K317N) may provide a molecular basis for further functional and genomic investigation of SCN5A.</AbstractText> |
2,054 | Immediate defibrillation versus interventions first in a swine model of prolonged ventricular fibrillation. | we compared time-dependent rescue shock success when delivered immediately, to defibrillation preceded by 3 min of CPR, with and without high dose epinephrine (HDE) in a swine model of prolonged ventricular fibrillation (VF). Our hypotheses were that pretreatment with CPR and HDE would produce higher rates of successful first-shock defibrillation and would prevent decay of the VF waveform, as measured by the scaling exponent (ScE), when compared to immediate defibrillation. We also sought to determine the predictive value of the ScE in determining post-shock outcomes.</AbstractText>we anesthetized and instrumented 60 domestic swine (19.6-26.4 kg). VF was induced electrically and was untreated for 8, 11 or 14 min. ECG was recorded digitally at a rate of 1000 samples/s with 5-s epochs used to calculate the ScE. We assigned randomly swine to seven groups (number denotes timing of first rescue shock). Three groups had rescue shocks as the first intervention (RSF) after 8 min of VF (RSF-8), 11 min of VF (RSF-11), or 14 min of VF (RSF-14): two groups had CPR for 3 min (then rescue shock) beginning at 8 min (CPR-11) or 11 min of VF (CPR-14); and two groups got CPR for 3 min with 0.1 mg/kg epinephrine (adrenaline) (then rescue shock) beginning at 8 min of VF (HDE-11) or 11 min of VF (HDE-14). Fixed-dose 70 J BDW rescue shocks were used for all shocks. Defibrillation outcome was classified immediately and 30 s post-shock as successful (either restoration of spontaneous circulation [ROSC] or restoration of organized electrical activity [ROEA]), or failed (remained in VF, or asystole). Data were analyzed with RMANOVA, multiple logistic regression, Fisher's exact tests, and ROC curves.</AbstractText>successful first-shock defibrillation occurred in 3/8 (38%) RSF-8; 1/9 (11%) RSF-11; 2/9 (22%) CPR-11; 7/9 (77%) HDE-11; 0/9 (0%) RSF-14; 0/7 (0%) CPR-14; and 1/8 (13%) HDE-14, (p=0.059 IRS-8 vs. HDE-11). First-shock ROSC occurred in 5/9 (56%) HDE-11 animals, 1/8 (13%) HDE-14 and zero in all other groups (p=0.03). Mean ScE values at 11 min VF for the RSF-11 (1.46) was higher than both CPR-11 (1.26), and HDE-11 (1.27); and RSF-14 (1.60) was higher than CPR-14 (1.47) and HDE-14 (1.46); group by time p=0.002. ROC areas under the curves using the ScE as a predictor of shock outcome were 0.84 for immediate success, 0.85 for sustained success, and 0.81 for ROSC.</AbstractText>HDE-11 showed a tendency for producing a higher rate of first-shock success and ROSC. Interventions prior to rescue shock prevented deterioration of the VF waveform and improved rescue shock outcomes. The ScE accurately predicted 81-85% of post-rescue shock outcomes.</AbstractText> |
2,055 | Brain metabolism during cardiopulmonary resuscitation assessed with microdialysis. | Microdialysis is an established tool to analyse tissue biochemistry, but the value of this technique to monitor cardiopulmonary resuscitation (CPR) effects on cerebral metabolism is unknown. The purpose of this study was to assess the effects of active-compression-decompression (ACD) CPR in combination with an inspiratory threshold valve (ITV) (=experimental CPR) vs. standard CPR on cerebral metabolism measured with microdialysis.</AbstractText>Fourteen domestic pigs were surfaced-cooled to a body core temperature of 26 degrees C and ventricular fibrillation was induced, followed by 10 min of untreated cardiac arrest; and subsequently, standard (n=7) CPR vs. experimental (n=7) CPR. After 8 min of CPR, all animals received 0.4 U/kg vasopressin IV, and CPR was maintained for an additional 10 min in each group; defibrillation was attempted after a total of 28 min of cardiac arrest, including 18 min of CPR.</AbstractText>In the standard CPR group, microdialysis measurements showed a 13-fold increase of the lactate-pyruvate ratio from 7.2+/-1.3 to 95.5+/-15.4 until the end of CPR (P<0.01), followed by a further increase up to 138+/-32 during the postresuscitation period. The experimental group developed a sixfold increase of the lactate-pyruvate ratio from 7.1+/-2.0 to 51.1+/-8.7 (P<0.05), and a continuous decrease after vasopressin. In the standard resuscitated group, but not during experimental CPR, a significant increase of cerebral glucose levels from 0.6+/-0.1 to 2.6+/-0.5 mM was measured (P<0.01).</AbstractText>Using the technique of microdialysis we were able to measure changes of brain biochemistry during and after the very special situation of hypothermic cardiopulmonary arrest. Experimental CPR improved the lactate-pyruvate ratio, and glucose metabolism.</AbstractText> |
2,056 | Antithrombin reduction after experimental cardiopulmonary resuscitation. | To determine whether activation of coagulation and inflammation during cardiac arrest results in a reduction of antithrombin (AT) and an increase in thrombin-antithrombin (TAT) complex during reperfusion.</AbstractText>Ventricular fibrillation (VF) was induced in ten anaesthetized pigs. After a 5-min non-intervention interval, closed-chest cardiopulmonary resuscitation (CPR) was performed for 9 min before defibrillation was attempted. If restoration of spontaneous circulation (ROSC) was achieved, the animals were observed for 4 h and repeated blood samples were taken for assay of AT, TAT and eicosanoids (8-iso-PGF(2alpha) and 15-keto-dihydro-PGF(2alpha)).</AbstractText>AT began to decrease 15 min after ROSC and the reduction continued throughout the observation period (P<0.05). The lowest mean value (79%) occurred 60 min after ROSC. The TAT level was increased during the first 3 h after ROSC (P<0.05), indicating thrombin generation. The eicosanoids were increased throughout the observation period (P<0.05).</AbstractText>AT is reduced and TAT and eicosanoids are increased after cardiac arrest, indicating activation of coagulation and inflammation.</AbstractText> |
2,057 | Defibrillation waveform and post-shock rhythm in out-of-hospital ventricular fibrillation cardiac arrest. | The importance of the defibrillation waveform on the evolving post-shock cardiac rhythm is uncertain. The primary objective of this study was to evaluate cardiac rhythms following the first defibrillation shock, comparing biphasic truncated exponential (BTE), monophasic damped sinusoidal (MDS), and monophasic truncated exponential (MTE) waveforms in patients experiencing out-of-hospital ventricular fibrillation cardiac arrest (OHCA).</AbstractText>We reviewed the automated external defibrillator (AED) and emergency medical services (EMS) records of 366 patients who suffered OHCA and were treated with defibrillation shocks by first-tier emergency responders between 1 January 1999 and 31 August 2002 in King County, Washington. The post first shock rhythms were determined at 5, 10, 20, 30, and 60 s and compared according to defibrillation waveform.</AbstractText>The MDS and BTE waveforms were associated with significantly higher frequency of defibrillation than the MTE waveform, though only the BTE association persisted to 30 and 60 s. No difference in defibrillation rates was detected between MDS and BTE waveforms. By 60 s, an organized rhythm was present in a greater proportion for BTE (40.0%) compared with MDS (25.4%, P=0.01) or MTE (26.5%, P=0.07).</AbstractText>In this retrospective cohort investigation, MDS and BTE waveforms had higher first shock defibrillation rates than the MTE waveform, while patients treated with the BTE waveform were more likely to develop an organized rhythm within 60 s of the initial shock. The results of this investigation, however, do not provide evidence that these surrogate advantages are important for improving survival. Additional investigation is needed to improve the understanding of the role of waveform and its potential interaction with other clinical factors in order to optimize survival in OHCA.</AbstractText> |
2,058 | VF recurrence: characteristics and patient outcome in out-of-hospital cardiac arrest. | Refibrillation after successful defibrillation in out-of-hospital cardiac arrest is a frequent event. Little is known of factors that predispose to the occurrence of refibrillation. The effect of recurrence of ventricular fibrillation (VF) on survival is not known.</AbstractText>Data of patients in out-of-hospital cardiac arrest were collected in a combined first responder and paramedic programme in Amsterdam, the Netherlands. Continuous recorded rhythm data of 322 patients covering the entire out-of-hospital resuscitation attempt was included in the analysis. Recurrence of VF was recorded, the patient and process characteristics were analysed in relation to the occurrence of refibrillation. The number of refibrillations was related to survival.</AbstractText>Of the studied patients 79% had at least one recurrence of VF, and a median number of two times 25-75%; one to four times). The median time from successful first shock to VF recurrence was 45 s (25-75%: 23-115 s). A significant inverse relation was found between the number of refibrillations and survival of out-of-hospital cardiac arrest. The recurrence of VF was independent of the underlying cardiac disorder, the time to defibrillation, the defibrillation waveform and other characteristics of the patient and the process. Anti-arrhythmics should be considered in all patients found in VF to reduce the number of recurrences.</AbstractText> |
2,059 | Difference in end-tidal CO2 between asphyxia cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest in the prehospital setting. | There has been increased interest in the use of capnometry in recent years. During cardiopulmonary resuscitation (CPR), the partial pressure of end-tidal carbon dioxide (PetCO2) correlates with cardiac output and, consequently, it has a prognostic value in CPR. This study was undertaken to compare the initial PetCO2 and the PetCO2 after 1 min during CPR in asphyxial cardiac arrest versus primary cardiac arrest.</AbstractText>The prospective observational study included two groups of patients: cardiac arrest due to asphyxia with initial rhythm asystole or pulseless electrical activity, and cardiac arrest due to acute myocardial infarction or malignant arrhythmias with initial rhythm ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). The PetCO2 was measured for both groups immediately after intubation and then repeatedly every minute, both for patients with and without return of spontaneous circulation (ROSC).</AbstractText>We analyzed 44 patients with asphyxial cardiac arrest and 141 patients with primary cardiac arrest. The first group showed no significant difference in the initial value of the PetCO2, even when we compared those with and without ROSC. There was a significant difference in the PetCO2 after 1 min of CPR between those patients with ROSC and those without ROSC. The mean value for all patients was significantly higher in the group with asphyxial arrest. In the group with VF/VT arrest there was a significant difference in the initial PetCO2 between patients without and with ROSC. In all patients with ROSC the initial PetCO2 was higher than 10 mmHg.</AbstractText>The initial PetCO2 is significantly higher in asphyxial arrest than in VT/VF cardiac arrest. Regarding asphyxial arrest there is also no difference in values of initial PetCO2 between patients with and without ROSC. On the contrary, there is a significant difference in values of the initial PetCO2 in the VF/VT cardiac arrest between patients with and without ROSC. This difference could prove to be useful as one of the methods in prehospital diagnostic procedures and attendance of cardiac arrest. For this reason we should always include other clinical and laboratory tests.</AbstractText> |
2,060 | Evidence favoring the use of an alpha2-selective vasopressor agent for cardiopulmonary resuscitation. | Both alpha1- and beta-adrenergic agonists increase the severity of global myocardial ischemic injury. We hypothesized that combined beta- and alpha1-adrenergic blockade would improve initial resuscitation and postresuscitation myocardial and neurological functions. We further hypothesized that the resulting alpha2-actions of relatively brief duration would favor improved functions compared with the more prolonged effect of nonadrenergic vasopressin.</AbstractText>Three groups of 5 male domestic pigs weighing 37+/-3 kg were investigated. Ventricular fibrillation was untreated for 7 minutes before the start of precordial compression, mechanical ventilation, and attempted defibrillation. Animals were randomized to receive central venous injections of equipressor doses of (1) epinephrine, (2) epinephrine in which both alpha1- and beta-adrenergic effects were blocked by previous administration of prazosin and propranolol, and (3) vasopressin during CPR. All but 1 animal were successfully resuscitated. After injection of epinephrine, significantly better cardiac output and fractional area change, together with lesser increases in troponin I, were observed after alpha1- and beta-adrenergic blockade. Postresuscitation neurological function was also improved after alpha1- and beta-block in comparison with unblocked epinephrine and after vasopressin.</AbstractText>Equipressor doses of epinephrine, epinephrine after alpha1- and beta-adrenergic blockade, and vasopressin were equally effective in restoring spontaneous circulation after prolonged ventricular fibrillation. However, combined alpha1- and beta-adrenergic blockade, which represented a predominantly selective alpha2-vasopressor effect, resulted in improved postresuscitation cardiac and neurological recovery.</AbstractText> |
2,061 | Noninvasive arrhythmia risk stratification in idiopathic dilated cardiomyopathy: results of the Marburg Cardiomyopathy Study. | Arrhythmia risk stratification with regard to prophylactic implantable cardioverter-defibrillator therapy is a completely unsolved issue in idiopathic dilated cardiomyopathy (IDC).</AbstractText>Arrhythmia risk stratification was performed prospectively in 343 patients with IDC, including analysis of left ventricular (LV) ejection fraction and size by echocardiography, signal-averaged ECG, arrhythmias on Holter ECG, QTc dispersion, heart rate variability, baroreflex sensitivity, and microvolt T-wave alternans. During 52+/-21 months of follow-up, major arrhythmic events, defined as sustained ventricular tachycardia, ventricular fibrillation, or sudden death, occurred in 46 patients (13%). On multivariate analysis, LV ejection fraction was the only significant arrhythmia risk predictor in patients with sinus rhythm, with a relative risk of 2.3 per 10% decrease of ejection fraction (95% CI, 1.5 to 3.3; P=0.0001). Nonsustained ventricular tachycardia on Holter was associated with a trend toward higher arrhythmia risk (RR, 1.7; 95% CI, 0.9 to 3.3; P=0.11), whereas beta-blocker therapy was associated with a trend toward lower arrhythmia risk (RR, 0.6; 95% CI, 0.3 to 1.2; P=0.13). In patients with atrial fibrillation, multivariate Cox analysis also identified LV ejection fraction and absence of beta-blocker therapy as the only significant arrhythmia risk predictors.</AbstractText>Reduced LV ejection fraction and lack of beta-blocker use are important arrhythmia risk predictors in IDC, whereas signal-averaged ECG, baroreflex sensitivity, heart rate variability, and T-wave alternans do not seem to be helpful for arrhythmia risk stratification. These findings have important implications for the design of future studies evaluating prophylactic implantable cardioverter-defibrillator therapy in IDC.</AbstractText> |
2,062 | Determinants of sudden cardiac death in individuals with the electrocardiographic pattern of Brugada syndrome and no previous cardiac arrest. | Patients with Brugada syndrome who were resuscitated from an episode of ventricular fibrillation are at high risk for recurrent sudden death. There is general agreement about the therapeutic strategy for these patients. Conversely, the prognosis and approach in patients with a diagnostic ECG but without a previous history of sudden cardiac death is controversial. We analyzed a large cohort of patients with Brugada syndrome without previous cardiac arrest to understand the determinants of prognosis.</AbstractText>A total of 547 patients with an ECG diagnostic of Brugada syndrome and no previous cardiac arrest were studied. The mean age was 41+/-15 years, and 408 were male. The diagnostic ECG was present spontaneously in 391 patients. In the remaining 156 individuals, the abnormal ECG was noted only after the administration of an antiarrhythmic drug. One hundred twenty-four patients had suffered from at least 1 episode of syncope. During programmed ventricular stimulation, a sustained ventricular arrhythmia was induced in 163 of 408 patients. During a mean follow-up of 24+/-32 months, 45 patients (8%) suffered sudden death or documented ventricular fibrillation. Multivariate analysis identified the inducibility of a sustained ventricular arrhythmia (P<0.0001) and a history of syncope (P<0.01) as predictors of events. Logistic regression analysis showed that a patient with a spontaneously abnormal ECG, a previous history of syncope, and inducible sustained ventricular arrhythmias had a probability of 27.2% of suffering an event during follow-up.</AbstractText>Individuals with Brugada syndrome and no previous cardiac arrest have a high risk of sudden death. Inducibility of ventricular arrhythmias and a previous history of syncope are markers of a poor prognosis.</AbstractText> |
2,063 | [Recurrent ventricular fibrillation in a patient with Brugada syndrome successfully treated with procainamide]. | Brugada syndrome is a clinical and electrocardiographic entity characterized by ST segment elevation in the right precordial ECG leads and sudden death or syncope secondary to malignant ventricular arrhythmia, and has a high recurrence rate. We report a patient with this syndrome who had received an automatic implantable defibrillator, who presented with multiple appropriate discharges because of recurrent episodes of ventricular fibrillation. All episodes were started by a premature ventricular beat of the same morphology and coupling interval. Endovenous procainamide administration, paradoxically, was effective in preventing new episodes. The beneficial antiarrhythmic effect of procainamide in this patient is discussed. |
2,064 | Sudden cardiac death with left main coronary artery occlusion in a patient whose presenting ECG suggested Brugada syndrome. | This article describes a patient who died suddenly during Holter ECG monitoring. A ventricular premature systole with an extremely short coupling interval of 240 ms was immediately followed by torsades de pointes, soon degenerating into ventricular fibrillation. Retrospective survey of the patient's medical records revealed an incomplete right bundle branch block (iRBBB) configuration with fluctuating saddle back-type ST elevation in leads V1 and V2, these suggesting Brugada syndrome. Autopsy showed complete thrombotic occlusion of the left main coronary artery. |
2,065 | Significance of external cardioversion induced atrial tachyarrhythmias. | External cardioversion is used to stop VT or VF in emergency. Supraventricular tachyarrhythmias are sometimes noted after cardioversion in patients known to be previously in sinus rhythm. The purpose of the study was to evaluate the significance of supraventricular tachyarrhythmias induced by external cardioversion. The study population consisted of 22 patients who developed supraventricular tachyarrhythmias after transthoracic cardioversion (300 J) delivered to stop a VT or VF induced by electrophysiological study. Defibrillation used monophasic waveform. Supraventricular tachyarrhythmias complicated 6% of cardioversions for VT; before cardioversion, all patients were in sinus rhythm. After cardioversion, three patients developed a paroxysmal reentrant supraventricular tachycardia (PSVT), which was stopped by atrial pacing. The remaining patients developed AF that lasted from 3 minutes to 24 hours (n = 4). One patient remained in AF. AF developed after a sinus pause or bradycardia, which was due to the interruption of VT or VF in nine patients or was noted just when VT or VF stopped (n = 10). The analysis of clinical data indicated that all three patients who presented a PSVT had a history of PSVT. Among patients who developed a sinus pause dependent AF, two had a history of AF. Among ten patients who developed AF at the time of cardioversion, three had a history of AF. During follow-up (1-9 years), no patient without a history of AF developed spontaneous AF, but patients with history of tachycardias had arrhythmia recurrences. The mechanism of cardioversion related tachycardias can be a pause related dispersion of atrial refractoriness or an adrenergic reaction induced by VT or VF, factors that precipitate arrhythmias in patients with history of atrial arrhythmias (one third of patients). In conclusion, supraventricular tachyarrhythmia is relatively frequent after external cardioversion for ventricular tachyarrhythmia, has no prognostic significance in patients without previous history of atrial arrhythmias, but in those with history of tachycardias is associated with a high risk of recurrence. |
2,066 | Distinct clinical features in the recipients of the implantable cardioverter defibrillator in Taiwan: a multicenter registry study. | Little information about the ICD is available from the Asian Pacific region. The purpose of this study was to characterize the clinical features in ICD patients in Taiwan and to compare these features with those in patients in the Western populations, mainly the Canadian Implantable Defibrillator Study (CIDS), the Antiarrhythmics versus Implantable Defibrillator (AVID) trial, and the Cardiac Arrest Study Hamburg (CASH) trial. From February 1995 to October 2001, 101 ICDs were implanted in 92 patients (78 [84%] men) in 12 hospitals. Clinical presentations included sudden cardiac death due to VF/VT in 35 (38%) patients, syncopal VT in 25 (27%), drug refractory nonsyncopal VT in 27 (29%), and unexplained syncope with inducible sustained VT/VF in 5 (6%). The mean age was significantly younger than that in CIDS or AVID (59 +/- 16 vs 63 +/- 9 years in CIDS, P = 0.02; vs 65 +/- 11 years in AVID, P < 0.001), but was comparable to that in CASH (59 +/- 16 vs 58 +/- 11 years in CASH, P = 0.75). The mean LVEF was significantly higher than that in CIDS or AVID (48 +/- 19% vs 34 +/- 15% in CIDS, P < 0.001; vs 32 +/- 13% in AVID, P < 0.001), but was comparable to that in CASH (48 +/- 19 vs 46 +/- 19% in CIDS, P = 0.83). The ICD patients in the current study also showed a higher incidence of normal heart (23 vs 4% in CIDS, P < 0.001; vs 3% in AVID, P < 0.001; vs 9% in CASH, P < 0.001) and cardiomyopathy (41% vs 10% in CIDS, P < 0.001; vs 15% in AVID, P < 0.001; vs 11% in CASH, P < 0.001), but a lower incidence of coronary artery disease (29% vs 83% in CIDS, P < 0.001; vs 82% in AVID, P < 0.001; vs 73% in CASH, P < 0.001). During a mean follow-up of 28 +/- 24 months, 13 (14%) patients died. Older age was the only factor associated with poorer survival after ICD implantation. Forty-seven (51%) patients received appropriate ICD discharges during follow-up. History of prior myocardial infarction was the only factor associated with an earlier first appropriate ICD discharge and LVEF < 0.35 the only factor associated with subsequent poorer survival after the first ICD discharge. In conclusion, this study demonstrated many distinct clinical features in our ICD population that were different from those in the Western populations. |
2,067 | Acute type A aortic dissection complicated with acute inferior myocardial infarction following aortic valve replacement. | Acute aortic dissection complicated with acute myocardial infarction (AMI) is the most fatal situation. We experienced the successful treatment for acute type A aortic dissection complicated with inferior AMI following aortic valve replacement (AVR). A 60-year-old man had had AVR for aortic regurgitation. Sixteen months after the AVR, he had a sudden onset of severe chest pain with complete atrioventricular block. Immediately, temporary pacing and cardiac catheterization were conducted, showing the occlusion of the right coronary artery due to acute type A aortic dissection. On his way to our hospital, direct current shock was conducted 3 times for ventricular fibrillation. We replaced the ascending aorta combined with coronary artery bypass grafting and the postoperative course was uneventful. The key to treat acute aortic dissection complicated with AMI is early accurate diagnosis, prompt temporary pacing for bradycardia, defibrillation for lethal arrhythmia and insertion of a perfusion catheter if possible. These preoperative hemodynamic stabilization gives us the chance to save these patients. |
2,068 | Complex intimal flaps in acute aortic dissection. | A 43-year-old man was emergently admitted and diagnosed as acute aortic dissection (Stanford type A). While being prepared for emergent operation he fell into hemodynamic hazard with repeated ventricular fibrillation and loss of consciousness. Massive aortic regurgitation and coronary disturbance due to a back-and-forth movement of an intimal flap through the aortic valve were the causes of the cardiogenic catastrophy. In addition, a completely torn intimal flap was intussuscepted into the origin of the brachiocephalic artery. This was thought to disturb the cerebral perfusion. Acute aortic dissection with such complex intimal flaps is very rare. In such cases cardiopulmonary bypass should be established to maintain the patient's cardiac function as soon as possible after diagnosis and the operation should be performed with sufficient brain protection. |
2,069 | Cardiotoxicities of paclitaxel in African Americans. | To assess the cardiac disturbances in African-American patients treated with paclitaxel.</AbstractText>One-hundred-nineteen African-American patients received paclitaxel for various cancers at Howard University Hospital during the years 1993-2001. Medical records of 100 patients were available for review. Sixty-seven percent were women and 33% were men. Ages ranged between 26-85 years (mean age 51 years). Medical records were reviewed for demographics, types of cancer, dosage and frequency of paclitaxel and other chemotherapeutic agents, events during paclitaxel infusion, initial and subsequent EKGs, and hospital admissions. We used the Chi-square test to compare EKG changes in patients with and without cardiac risk factors.</AbstractText>Ninety patients received paclitaxel as second-line chemotherapy, and 10 patients were treated with paclitaxel as a single agent. Dosage of paclitaxel ranged from 75-200 mg/square meter and was administered every 1-3 weeks. The electrocardiogram readings revealed the following cardiac events: 26% sinus tachycardia, 13% non-specific T-wave changes, 6% myocardial infarction, 4% prolonged QT interval, 4% left-bundle branch block, 3% right-bundle branch block, 3% sinus bradycardia, 2% premature atrial contractions, 2% premature ventricular contractions, 2% atrial flutter, and 1% atrial fibrillation. Eighty percent of the patients had risk factors for coronary artery disease. These cardiac disturbances were observed from day one to a maximum of eight years after receiving the chemotherapy and were independent of dosage of paclitaxel. Sixty percent of our study population had underlying co-morbid conditions, such as dehydration, anemia, sepsis, and hypoxia. The EKG changes observed in patients with underlying cardiac risk factors were statistically significant (p<0.0001).</AbstractText>Paclitaxel was not associated with significant symptomatic cardiac disturbances during infusion in our study population. Caution should be exercised in patients with underlying cardiac disease and risk factors for coronary artery disease. However more prospective studies with closer follow-up during paclitaxel infusion are needed to assess its cardiotoxicities.</AbstractText> |
2,070 | Improvement in exercise performance after successful cardioversion in patients with persistent atrial fibrillation and symptoms of heart failure. | Loss of atrial systolic function as well as fast and irregular ventricular response result in the impairment of hemodynamic function in patients with atrial fibrillation (AF). AF is considered to be a less efficient cardiac rhythm than sinus rhythm (SR), and accounts for the symptoms of reduced exercise tolerance, such as fatigue, tiredness or dyspnoea. In more severe cases, the hemodynamic alterations can result in heart failure.</AbstractText>To assess exercise performance before and one month after cardioversion of persistent AF.</AbstractText>We studied 42 patients with mild to moderate clinically stable heart failure and persistent AF (median duration 7 months) with controlled ventricular rate. They underwent submaximal exercise testing 24 hours before cardioversion and one month after cardioversion. Exercise capacity was determined during symptom-limited exercise testing, according to a modified Bruce protocol with peak VO(2) analysis.</AbstractText>Thirty-five (83%) patients were successfully cardioverted to SR. One month after cardioversion 29 patients remained in SR (SR group) while 6 had recurrence of AF, and, together with patients with unsuccessful cardioversion, formed the AF group (n=13). Baseline patient characteristics did not differ between the SR and AF groups. Left ventricular ejection fraction (52.7+/-10.2% vs 56.5+/-9.6%, NS) and exercise tolerance (peak VO(2) 19.85+/-3.5 ml/min/kg vs 22.2+/-3,4 ml/kg/min, NS; and exercise duration 9.5+/-3.4 min vs 10.6+/-2.4 min; NS) were similar in both groups before cardioversion. Successful cardioversion resulted in a mean decrease in resting heart rate of 28 beats/minute (94.7+/-10.3 vs 66.7+/-9.7 beats/min, p<0.05), measured 30 days after cardioversion, and a significant improvement in exercise tolerance in the SR group: exercise duration increased from 9.5+/-3.4 min to 13.7+/-3.2 min, p<0.05; and peak oxygen consumption increased from 19.85+/-3.5 ml/min/kg to 32.2+/-3.6 ml/min/kg, p<0.05. No improvement was observed in the AF group.</AbstractText>Restoration of sinus rhythm in patients with persistent AF is associated with a significant improvement in exercise capacity one month after cardioversion.</AbstractText> |
2,071 | Frequent ICD shocks due to double sensing in patients with bi-ventricular implantable cardioverter defibrillators. | Biventricular pacing has emerged as a modality for treatment of patients with heart failure. Combined biventricular pacers and implantable cardioverter defibrillators offer treatment of heart failure as well as protection from sudden cardiac death. However, inappropriate ICD shocks as a result of double sensing due to widely spaced ventricular bipoles may pose a significant problem in these patients. We examined the ICD records of twenty-three patients with biventricular ICDs, and evaluated all episodes of double sensing that resulted in aborted or delivered therapy. In follow-up of 3.7 +/- 2.6 months, thirty-three shocks in fifteen episodes occurred in five patients (21.7%) due to double sensing. Four patients (17.4%) had aborted shocks due to double sensing. All episodes resulting in shock occurred because of sinus tachycardia or supraventricular tachycardia above the upper programmed pacing rate of the device with resultant AV conduction and double sensing of the nonpaced ventricular depolarization. In conclusion, double sensing of the R-wave is a common and clinically important cause of inappropriate ICD detection and shock in patients with biventricular ICDs. Appropriate programming of the ICD can prevent episodes of inappropriate shocks. |
2,072 | Rate-control versus conversion strategy in postoperative atrial fibrillation: trial design and pilot study results. | Atrial fibrillation (AF) remains a frequent complication of cardiac surgery. The optimal treatment strategy has not been established. Retrospective studies have suggested that a primary rate-control strategy may be equivalent to a strategy that restores sinus rhythm. Fifty patients with postoperative atrial fibrillation were randomly assigned to a strategy of antiarrhythmic therapy +/- electrical cardioversion or ventricular rate control. Anticoagulation with heparin overlapped with coumadin was administered to both arms. The primary endpoint of the study was time to conversion to sinus rhythm analyzed by the Kaplan-Meier method. The effects of strategy on hospital length of stay was examined as well as the incidence of recurrent AF. This study demonstrated no significant difference between an antiarrhythmic conversion strategy (n = 27) and a rate-control strategy (n = 23) in time to conversion to sinus rhythm (11.2 +/- 3.2 vs. 11.8 +/- 3.9 hours; p = 0.8). With Cox multivariate analysis to control for the effects of age, sex, beta-blocker usage, and type of surgery, the conversion strategy showed a trend toward reducing the time from treatment to restoration of sinus rhythm (p = 0.08). The length of hospital stay was reduced in the antiarrhythmic arm compared with the rate-control strategy (9.0 +/- 0.7 vs. 13.2 +/- 2.0 days; p = 0.05). In hospital relapse rates in the antiarrhythmic arm were 30% compared with 57% in the rate-control strategy (p = 0.24). At the termination of the study, 91% of the patients in the rate-control arm were in sinus rhythm compared with 96% in the antiarrhythmic arm. In conclusion, this pilot study shows little difference between a rate-control strategy and a strategy to restore/maintain sinus rhythm. Regardless of the strategy, majority of patients will be in sinus rhythm after two months. A larger randomized, controlled study is needed to assess the impact of restoration of sinus rhythm on length of stay. |
2,073 | Pharmacological approach for the prevention of atrial fibrillation after cardiovascular surgery. | Atrial fibrillation (AF) is a common complication of cardiovascular surgery. The two most important risk factors for its development are advancing age and a preoperative history of AF. Long-term sequelae, such as a stroke, are uncommon, however, atrial fibrillation frequently results in increased length and cost of hospitalization. Strategies to prevent postoperative AF include perioperative beta-blockers, amiodarone, and atrial pacing. These strategies are most effective in high-risk patients. When AF does occur, treatment includes control of the ventricular rate, systemic anticoagulation, and conversion to sinus rhythm. |
2,074 | Amiodarone prevents symptomatic atrial fibrillation and reduces the risk of cerebrovascular accidents and ventricular tachycardia after open heart surgery: results of the Atrial Fibrillation Suppression Trial (AFIST). | Atrial fibrillation (AF) is a common complication after cardiothoracic surgery (CTS). The role of amiodarone added to beta blocker as a preventive strategy in elderly patients undergoing CTS is not known. The Atrial Fibrillation Suppression Trial (AFIST) was a double blind, placebo-controlled trial that evaluated the efficacy of oral amiodarone in patients 60 years or older undergoing CTS. Beta blockers were administered as part of a critical pathway.</AbstractText>Elderly patients (n = 220, mean age 72 +/- 6.7 years) received amiodarone (n = 120) or placebo (n = 100). Patients enrolled less than 5 days before CTS received 6 g of drug over 6 days beginning on the day prior to OHS. Patients enrolled 5 days before CTS received 7 g of study drug over 9-10 days, starting on preoperative day 4 or 5.</AbstractText>Amiodarone treated patients had a lower incidence of AF (22.5% vs. 38%, p = 0.01), symptomatic AF (4.2% vs. 18%, p = 0.001), cerebral vascular accident (1.7 vs. 7.0%, p = 0.04), and ventricular tachycardia (1.7% vs. 7.0%, p = 0.04) vs. placebo. Beta blocker use (87.5% vs. 91.0% ), nausea (26.7% vs. 16%, p = 0.056), symptomatic bradycardia (7.5% vs. 7%, p = 0.89), hypotension (14.2% vs. 10.0%) and 30 day mortality (3.3 vs. 4.0%, p = 0.79) were similar. Amiodarone treated patients receiving the 4/5 day preoperative regimen had a reduced incidence of AF (19.6% vs. 38%, p = 0.013), while those receiving the 1-day preoperative regimen showed a trend (25% vs. 38%, p = 0.06) vs. placebo.</AbstractText>In an elderly population undergoing CTS, Amiodarone prophylaxis reduces AF, the incidence of symptomatic AF, cerebrovascular accident and ventricular tachycardia.</AbstractText> |
2,075 | Rhythm versus rate control after ablation and pacing for paroxysmal atrial fibrillation: clinical implications of the PAF 2 trial. | Four recent randomized controlled studies that compared rhythm control versus rate control therapy demonstrated that rate control therapy is an acceptable alternative to rhythm control therapy. The control of heart rate achievable with pharmacologic therapy is imperfect and, in many patients, difficult to obtain. Ablation and pacing therapy offers better control of heart rate than drug therapy. The aim of the PAF 2 trial was to evaluate the effect of antiarrhythmic drug therapy on long-term maintenance of normal sinus rhythm after ablation and pacing therapy and to evaluate the effect of maintenance of normal sinus rhythm on major clinical events, quality of life and cardiac performance and, therefore, to evaluate whether antiarrhythmic drug strategy yields any additional benefit to ablation and pacing therapy. In this multicenter randomized controlled trial, 68 patients with severely symptomatic paroxysmal atrial fibrillation were assigned, after successful atrioventricular junction ablation and pacing treatment, to antiarrhythmic drug therapy with amiodarone, propafenone, flecainide or sotalol and were compared with 69 patients assigned, after successful AV junction ablation and pacing treatment, to no antiarrhythmic drug therapy. Although patients in the antiarrhythmic drug arm had a reduction in the risk of developing chronic atrial fibrillation, there was no clinical benefit beyond that obtained with ablation and pacing alone. On the contrary, antiarrhythmic therapy was associated with more serious adverse clinical events, i.e. episodes of heart failure and hospitalization. This suggests that the control of ventricular rhythm by ablation and pacing has a greater beneficial effect on short-term clinical outcome than the preservation of atrial contraction. Therefore, the results of PAF2 study are consistent with the drug trials comparing rhythm and rate control. |
2,076 | Towards a consensus in rate versus rhythm control for management of atrial fibrillation: insights from the PIAF trial. | Knowledge on the pathophysiology of atrial fibrillation is rapidly expanding and identification of focally localized triggers have led to the development of new treatment options for this arrhythmia. Conversely, the clinical decision whether to restore and maintain sinus rhythm or simply control the ventricular rate has remained a matter of intense debate. The Pharmacological Intervention in Atrial Fibrillation (PIAF) trial was the first pilot-study to prospectively assess the symptomatic benefits of rate versus rhythm control in patients with persistent symptomatic AF. Since the publication of PIAF, results from three additional randomized clinical trials have confirmed and extended the PIAF notion of equivalent outcomes with regard to symptoms, quality of life, and cardiovascular events. This review summarizes the rationale and results of PIAF in an attempt to update and discuss the clinical relevance of these findings in the light of the other studies and with regard to individual treatment options. |
2,077 | Clinical and haemodynamic profiles of young, middle aged, and elderly patients with mitral stenosis undergoing mitral balloon valvotomy. | To compare the clinical characteristics, haemodynamic findings, and symptomatic outcome in four age groups of patients in the UK undergoing percutaneous mitral balloon valvotomy.</AbstractText>A review of patients with mitral stenosis treated by balloon dilatation.</AbstractText>Western General Hospital, Edinburgh, a cardiac referral centre.</AbstractText>Of 405 patients who had mitral balloon valvotomy, 19 were aged under 40 years, 101 aged 40-54, 173 aged 55-69, and 112 were 70 years old or more. Medical co-morbidity and Parsonnet score for risk at surgery increased notably with age. Older patients had greater symptomatic limitation and a more severe degree of mitral stenosis, with more valve degenerative change. The incidence of atrial fibrillation, mitral reflux, left ventricular impairment, coronary artery disease, and aortic valve disease increased progressively with age. Before balloon dilatation the right ventricular systolic and left atrial pressures were similar in all age groups, but younger patients had a higher transmitral gradient and cardiac output. After balloon dilatation the younger patients achieved a greater increase in valve area. Complications of balloon valvotomy were more common in the older patients. At five years after balloon dilatation the percentages of patients in each age group who were in New York Heart Association classes I and II were 87%, 63%, 36%, and 19%, respectively. Mortality at five years was 0%, 5%, 31%, and 59%.</AbstractText>Percutaneous balloon valvotomy gives a good haemodynamic and symptomatic result in patients under 55. In older patients improvement is often less pronounced and less sustained, but the procedure is a well tolerated palliative treatment for those unsuitable for surgery.</AbstractText> |
2,078 | Evolution of the atrial fibrillation substrate in experimental congestive heart failure: angiotensin-dependent and -independent pathways. | Augmented atrial apoptosis, angiotensin II expression, and related signalling pathway activation have been shown in clinical atrial fibrillation (AF), but their significance is poorly understood. This study evaluated temporal relationships between changes in atrial histopathology, selected signalling mediators, and AF promotion, as well as effects of angiotensin-converting enzyme (ACE) inhibition, in a canine model of congestive heart failure (CHF).</AbstractText>Dogs were subjected to ventricular tachypacing (VTP) for varying periods up to 5 weeks. Apoptosis was assessed by terminal dUTP nick-end labelling (TUNEL) and DNA fragmentation. Protein expression was determined by Western blot, angiotensin II concentration by ELISA (tissue) and radioimmunoassay (plasma), and caspase-3 activity by enzymatic assay. Histopathological analyses were used to quantify fibrosis, inflammation, and cell death.</AbstractText>Significant apoptosis developed 24 h after VTP onset and persisted for 1 week, returning to baseline thereafter. Apoptosis was preceded by increases in tissue (but not plasma) angiotensin II concentration; enhanced expression of phosphorylated mitogen-activated protein (MAP) kinases p38, JNK, and ERK; and augmented ratios of the proapoptotic protein Bax to the antiapoptotic protein Bcl-2. Increased cell death, leukocyte infiltration, and caspase-3 activity occurred at the time of peak apoptosis. Apoptosis was followed by interstitial fibrosis, which peaked at 5 weeks. ACE inhibition (enalapril) prevented increases in tissue angiotensin II concentration, phosphorylated ERK expression, Bax/Bcl-2 ratio, and cellular apoptosis, but did not affect total cell death, leukocyte infiltration, JNK or p38 activation, and reduced but did not eliminate tissue fibrosis.</AbstractText>AF-promoting atrial structural remodeling in experimental CHF involves angiotensin II-dependent and angiotensin II-independent pathways. Significant apoptosis occurs, but prevention of apoptosis by ACE inhibition only partially prevents atrial structural remodeling.</AbstractText> |
2,079 | Atrial effects of the novel K(+)-channel-blocker AVE0118 in anesthetized pigs. | AVE0118 is a novel blocker of the K(+) channels K(v)1.5 and K(v)4.3 which are the molecular basis for the human cardiac ultrarapid delayed rectifier potassium current (I(Kur)) and the transient outward current (I(to)). The objective of this study was to investigate the effect of AVE0118 on atrial refractoriness (ERP), left atrial vulnerability (LAV) and on left atrial monophasic action potentials (MAP) in pentobarbital anesthetized pigs in comparison to the selective I(Kr) blocker dofetilide in order to assess the therapeutic potential of the novel K(+) channel blocker for atrial fibrillation.</AbstractText>Atrial ERP was determined with the S1-S2-stimulus method in the free walls of left and right atrium at 240, 300 and 400 ms basic cycle length (BCL). The inducibility of mostly nonsustained atrial tachyarrhythmias by the premature S2 extrastimulus, which is very high in the left pig atrium and referred to as LAV, was evaluated before and after drugs. Left atrial epicardial MAP was recorded to study the influence of the potassium channel blockers on the time course of repolarization. Left ventricular epicardial MAP, ERP and QT interval were measured to investigate a possible effect of AVE0118 on ventricular repolarization.</AbstractText>ERPs determined at 240, 300 and 400 ms BCL were significantly shorter in the left vs. right atrium (99+/-3, 106+/-4 and 113+/-3 ms vs. 133+/-4 ms, 142+/-4 and 149+/-5, respectively; p<0.001; n=21). AVE0118 administered i.v. dose-dependently prolonged the atrial ERP independent from rate and inhibited LAV (100% at 0.5 and 1 mg/kg) while having no effect at all on the corrected QT (QTc) interval. At 1 mg/kg (n=5) AVE0118 prolonged left vs. right atrial ERP by 49.6+/-4.1 ms vs. 37.7+/-9.7 ms (means+/-SEM of changes at 240, 300, and 400 ms BCL), respectively, corresponding to a relative increase of 53.2+/-6.2% vs. 27.6+/-6.8% (p<0.05 for percent increase of left vs. right atrial ERP). In a separate group of pigs (n=5) AVE0118 had no effect on left ventricular ERP at 333, 400 and 500 ms BCL and no effect on MAP duration and QT at 600 ms BCL. After 1 mg/kg of AVE0118 the atrial MAP was significantly prolonged already at 10% repolarization (P<0.05; n=7) reaching the maximum at 40% repolarization. In contrast to AVE0118 the effect of dofetilide (10 microg/kg) on atrial MAP started to become significant only at 60% repolarization (n=6) with a maximum increase at 90%. Dofetilide, which prolonged the QTc interval by 16.9% (P<0.001), had a significantly stronger effect on right (34.7+/-5 ms) vs. left atrial ERP (23.5+/-7 ms) at 300 ms BCL, respectively, but did not significantly inhibit LAV (14%; n=6).</AbstractText>The novel K(+) channel blocker AVE0118 prolonged atrial ERP and showed strong atrial antiarrhythmic efficacy with no apparent effect on ventricular repolarization in pigs in vivo.</AbstractText> |
2,080 | Decreased nocturnal standard deviation of averaged NN intervals. An independent marker to identify patients at risk in the Brugada Syndrome. | Risk-stratification of asymptomatic Brugada Syndrome (BS) patients remains a key-issue. A typical spontaneous BS-ECG pattern and ventricular tachycardia (VT)/ventricular fibrillation (VF) inducibility are two recognized risk markers. The aim of the study was to identify additional risk markers in asymptomatic BS.</AbstractText>We have compared Holter recordings in symptomatic and in asymptomatic patients with BS. Heart rate variability (HRV), QT-interval rate-dependence and ST-segment elevation (ST-SE) were analysed. The study population included 47 BS patients (M=36, mean age=45+/-13 years) with a malignant ventricular arrhythmia in 11 cases, an unexplained syncope in 10 cases and no symptoms in the remaining 26 cases. A typical spontaneous BS-ECG was present in 21 cases and a drug-induced BS-ECG in 26 cases. A downward trend of the time domain variables of HRV was observed. During the nocturnal period, standard deviation (SD) of the 5min averaged NN intervals (SDANN) (46+/-13 vs 57+/-18ms, P=0.02) and ultra low frequency component (3287+/-2312 vs 5030+/-3270 ms(2), P=0.04) were significantly lower in symptomatic versus asymptomatic patients. In contrast, no difference was found in QT-interval rate dependence and in ST-SE. At multivariate logistic regression, VT/VF inducibility, typical spontaneous BS-ECG and a decreased nocturnal SDANN were associated with arrhythmic events (P=0.003).</AbstractText>A decreased nocturnal SDANN was an independent marker of arrhythmic events in these BS patients.</AbstractText> |
2,081 | Association between brain natriuretic peptide and extracellular water in hemodialysis patients. | Brain natriuretic peptide (BNP) is a hormone released by the left ventricle (LV) as a consequence of pressure or volume load. BNP increases in left ventricle hypertrophy (LVH), LV dysfunction, and it can also predict cardiovascular mortality in the general population as well as those undergoing hemodialysis (HD). We investigated the association between BNP and volume load in HD patients.</AbstractText>We studied 32 HD patients (60 +/- 17.1 years) treated thrice-weekly for at least 6 months. Exclusion criteria were: LV dysfunction, atrial fibrillation, malnutrition. Blood chemistries and BNP were determined on mid-week HD day. Blood pressure (BP) and cardiac diameters were determined on mid-week inter-HD day by using 24-hour ambulatory blood pressure monitoring and echocardiography. Bioimpedance was performed after HD and extracellular water (ECW%), calculated as a percentage of total body water, was considered as the index of volume load.</AbstractText>Patients were divided into quartiles of 8 patients depending on the BNP value: 1st qtl BNP < or =45.5 pg/ml (28.4 +/- 10.9 pg/ml), 2nd qtl BNP > 45.5 pg/ml and < or =99.1 pg/ml (60.9 +/- 15.8 pg/ml), 3rd qtl BNP > 99.1 pg/ml and < or =231.8 pg/ml (160.5 +/- 51.8 pg/ml), 4th qtl BNP > 231.8 pg/ml (664.8 +/- 576.6 pg/ml). No inter-quartile differences were reported in age, HD age, body mass index spKt/V, or blood chemistries. As expected patients in the 4th BNP quartile showed the highest values of 24-hour pulse pressure (PP) and LV mass index (LVMi). The study of body composition revealed significant differences in ECW%, which was higher in the 4th quartile when compared to the others (4th q: 50 +/- 9.6%, vs 1st q. 40.1 +/- 2.4%, 2nd q. 41.9 +/- 5%, 3rd q. 42.8 +/- 6.9%). Using multiple stepwise linear regression where BNP was the dependent variable, and PP and ECW% the independent variables, only ECW% maintained statistical significance as a predictor of BNP levels (PP: Beta = 0.86, p = 0.58; ECW%: Beta = 0.64, p < 0.001 p < 0.001).</AbstractText>Few studies have investigated the relationship between plasma BNP and volume load, and direct evidence is lacking. We used bioimpedance and the determination of ECW% to assess volume state in HD patients finding an association between BNP and ECW. The increased synthesis and release of BNP from the LV in HD patients appear to be mainly related to volume stress rather than to pressure load.</AbstractText>Copyright 2003 S. Karger AG, Basel</CopyrightInformation> |
2,082 | Long-term treatment with glibenclamide increases susceptibility of streptozotocin-induced diabetic rat heart to reperfusion-induced ventricular tachycardia. | This study investigated the effects of long-term treatment with glibenclamide (GLIB) on the susceptibility of streptozotocin (STZ)-induced diabetic heart to ischemia/reperfusion insults. Starting 4 weeks after the injection of STZ, rats were treated with GLIB (0.1 mg/kg, ip, three times a week, STZ-GLIB group) or vehicle (STZ-VEH group) for 8 weeks. The recovery of cardiac performance, released creatine kinase (CK), and incidence of ventricular arrhythmias were studied during the reperfusion period in isolated hearts from rats in STZ-GLIB (n = 14) and in STZ-VEH groups (n = 13) and from age-matched control rats (CNT group, n = 14). Each heart was subjected to 5 min of global low-flow ischemia followed by 25 min of no-flow ischemia, with a subsequent 30 min of reperfusion. Plasma glucose level was not significantly different between the STZ-GLIB and STZ-VEH groups. The recovery of cardiac performance and the released CK during reperfusion period were significantly lower in both STZ-VEH and STZ-GLIB groups than in the CNT group (P < 0.01 and P < 0.05, respectively). Reperfusion resulted in an incidence of ventricular fibrillation in 23% and 21% in STZ-VEH and STZ-GLIB groups, respectively (P = ns). These values were significantly lower than that of the CNT group (100%, P < 0.001 for both). More importantly, the incidence of ventricular tachycardia in the STZ-GLIB group was significantly higher than that in the STZ-VEH group (93% vs 54%, P < 0.05) and was not significantly different from that in the CNT group (93% vs 100%, P = ns). The results suggest that STZ-induced protection against reperfusion-induced ventricular arrhythmias in diabetic heart may be partially abrogated by long-term treatment with GLIB. |
2,083 | [Indications for the implantable cardiac defibrillator]. | The indications of the implantable cardiac defibrillator (ICD) have enlarged over the time. This has been facilitated by the technological progress which permit the device to be more effective and its implantation to be more simple. So, the implantation rate has increased all over the world but especially in the United States. The ICD was initially proposed in case of recurrent cardiac arrests due to ventricular fibrillation. Later, indications have enlarged. They concern at the present time not only the secondary but also the primary prevention of the sudden cardiac death. Indications in secondary prevention are based on the results of randomized studies which have clearly demonstrated the superiority of the device if compared to the antiarrhythmic drugs. The first indication of the ICD in the primary prevention has been defined by the MADIT study. Since, other studies have tried to define high risk population in whom a prophylactic implantation of an ICD should be justified. However, other clinical trials are still necessary to precise the indications of the ICD in some disease states (hypertrophic cardiomyopathy, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, Brugada syndrome) which can be complicated by arrhythmic sudden death. Indeed, indications in these diseases are still based on small studies and in the opinion of experts. |
2,084 | Ventricular arrhythmia induced by sodium channel blocker in patients with Brugada syndrome. | We administered pilsicainide chloride, a class Ic pure sodium channel blocker, to patients with Brugada syndrome (BS) and evaluated the occurrence of ventricular arrhythmia (VA) and T-wave alternans (TWA).</AbstractText>Ventricular arrhythmia and TWA are sometimes induced by a sodium channel blocker challenge test in BS patients, but the significance of the induced VA and TWA is not known.</AbstractText>Pilsicainide was administered to 65 patients with BS (10 symptomatic and 55 asymptomatic patients), and the occurrence of VA, TWA, and change of electrocardiogram were evaluated. Electrophysiologic study was performed in 57 patients, and the induction of VA by programmed electrical stimulation (PES) was evaluated.</AbstractText>Ventricular arrhythmia was not induced by administration of pilsicainide in 55 patients (no-VA group). Administration of pilsicainide-induced VA in 10 patients (Pil-VA group) and polymorphic ventricular tachycardia in four patients. Pilsicainide-induced VA in 60% of the symptomatic patients but in only 7% of asymptomatic patients (p < 0.01). ST level, QTc, and indexes of cardiac conduction in the Pil-VA group were not different from those in the no-VA group. Ventricular fibrillation was induced by PES in 67% of the patients in the Pil-VA group and in 33% of the patients in the no-VA group. In six cases, macroscopic TWA occurred in association with pilsicainide-induced VA, but TWA occurred in only one patient without pilsicainide-induced arrhythmia.</AbstractText>Administration of a sodium channel blocker results in induction of not only ST-elevation but also VA and TWA in patients with BS.</AbstractText> |
2,085 | Increased exercise ejection fraction and reversed remodeling after long-term treatment with metoprolol in congestive heart failure: a randomized, stratified, double-blind, placebo-controlled trial in mild to moderate heart failure due to ischemic or idiopathic dilated cardiomyopathy. | the effects of long-term administration of beta-blockers on left ventricular (LV) function during exercise in patients with ischemic heart disease (IHD) and idiopathic dilated cardiomyopathy (DCM) are controversial.</AbstractText>patients with stable congestive heart failure (CHF) (New York heart association [NYHA] class II and III) and ejection fraction (EF) < or =0.40 were randomized to metoprolol, 50 mg t.i.d. or placebo for 6 months. Patients were divided into two groups: ischemic heart disease (IHD) and idiopathic dilated cardiomyopathy (DCM). The mean EF was 0.29 in both groups and 92% were taking angiotensin-converting enzyme (ACE) inhibitors. In the IHD group, 84% had suffered a myocardial infarction (MI) and 64% had undergone revascularization at least 6 months before the study. LV volumes were measured by equilibrium radionuclide angiography. Mitral regurgitation was assessed by Doppler echocardiography. All values are changes for metoprolol subtracted by changes for placebo.</AbstractText>metoprolol improved LV function markedly both at rest and during sub-maximal exercise in both groups. The mean increase in EF was 0.069 at rest (P<0.001) and 0.078 during submaximal exercise (P<0.001). LV end-diastolic volume decreased by 22 ml at rest (P=0.006) and by 15 ml during exercise (P=0.006). LV end-systolic volume decreased by 23 ml both at rest (P=0.001) and during exercise (P=0.004). Exercise time increased by 39 s (P=0.08). In the metoprolol group, mitral regurgitation decreased (P=0.0026) and only one patient developed atrial fibrillation vs. eight in the placebo group (P=0.01).</AbstractText>metoprolol improves EF both at rest and during submaximal exercise and prevents LV dilatation in mild to moderate CHF due to IHD or DCM.</AbstractText> |
2,086 | Mechanistic inquiry into decrease in probability of defibrillation success with increase in complexity of preshock reentrant activity. | Energy requirements for successful antiarrhythmia shocks are arrhythmia specific. However, it remains unclear why the probability of shock success decreases with increasing arrhythmia complexity. The goal of this research was to determine whether a diminished probability of shock success results from an increased number of functional reentrant circuits in the myocardium, and if so, to identify the responsible mechanisms. To achieve this goal, we assessed shock efficacy in a bidomain defibrillation model of a 4-mm-thick slice of canine ventricles. Shocks were applied between a right ventricular cathode and a distant anode to terminate either a single scroll wave (SSW) or multiple scroll waves (MSWs). From the 160 simulations conducted, dose-response curves were constructed for shocks given to SSWs and MSWs. The shock strength that yielded a 50% probability of success (ED(50)) for SSWs was found to be 13% less than that for MSWs, which indicates that a larger number of functional reentries results in an increased defibrillation threshold. The results also demonstrate that an isoelectric window exists after both failed and successful shocks; however, shocks of strength near the ED(50) value that were given to SSWs resulted in 16.3% longer isoelectric window durations than the same shocks delivered to MSWs. Mechanistic inquiry into these findings reveals that the two main factors underlying the observed relationships are 1) smaller virtual electrode polarizations in the tissue depth, and 2) differences in preshock tissue state. As a result of these factors, intramural excitable pathways leading to delayed breakthrough on the surface were formed earlier after shocks given to MSWs compared with SSWs and thus resulted in a lower defibrillation threshold for shocks given to SSWs. |
2,087 | A randomized study of prophylactic catheter ablation in asymptomatic patients with the Wolff-Parkinson-White syndrome. | Young age and inducibility of atrioventricular reciprocating tachycardia or atrial fibrillation during invasive electrophysiological testing identify asymptomatic patients with a Wolff-Parkinson-White pattern on the electrocardiogram as being at high risk for arrhythmic events. We tested the hypothesis that prophylactic catheter ablation of accessory pathways would provide meaningful and durable benefits as compared with no treatment in such patients.</AbstractText>From 1997 to 2002, among 224 eligible asymptomatic patients with the Wolff-Parkinson-White syndrome, patients at high risk for arrhythmias were randomly assigned to radio-frequency catheter ablation of accessory pathways (37 patients) or no treatment (35 patients). The end point was the occurrence of arrhythmic events over a five-year follow-up period.</AbstractText>Patients assigned to ablation had base-line characteristics that were similar to those of the controls. Two patients in the ablation group (5 percent) and 21 in the control group (60 percent) had arrhythmic events. One control patient had ventricular fibrillation as the presenting arrhythmia. The five-year Kaplan-Meier estimates of the incidence of arrhythmic events were 7 percent among patients who underwent ablation and 77 percent among the controls (P<0.001 by the log-rank test); the risk reduction with ablation was 92 percent (relative risk, 0.08; 95 percent confidence interval, 0.02 to 0.33; P<0.001).</AbstractText>Prophylactic accessory-pathway ablation markedly reduces the frequency of arrhythmic events in asymptomatic patients with the Wolff-Parkinson-White syndrome who are at high risk for such events.</AbstractText>Copyright 2003 Massachusetts Medical Society</CopyrightInformation> |
2,088 | "Demand" stimulation of latissimus dorsi heart wrap: experience in humans and comparison with adynamic girdling. | Questionable systolic assistance and latissimus dorsi (LD) muscular degeneration as a result of continuous electrical stimulation constitute important drawbacks to dynamic cardiomyoplasty. To avoid full transformation of the LD and thereby cause better systolic assistance, a new stimulation protocol was developed. Fewer impulses per day are delivered so that the LD wrap has daily periods of rest (demand), based on a heart rate cutoff. We describe our experience of demand dynamic wrapping by discriminating between patients with active systolic assistance and those with a passive girdle effect (adynamic-girdling).</AbstractText>Fourteen patients with primary dilated cardiomyopathy (13 men, 1 woman; mean age, 58.2 +/- 5.8 years; 12 sinus rhythm, 2 atrial fibrillation) underwent dynamic cardiomyoplasty between 1993 and 1996 as well as the demand protocol at different intervals. Clinical, echocardiographic, mechanographic, and cardiac invasive assessment records, as well as cardiovascular events (death and arrhythmias), were retrospectively reviewed. The patients were divided into two groups on the basis of the mechanographic measurement of speed of contraction of the heart wrap, as measured by tetanic fusion frequency analysis before starting demand stimulation: demand dynamic wrapping patients with fast LD (high tetanic fusion frequency, 7 patients), and adynamic-girdling patients with slow LD contraction times (low tetanic fusion frequency, 7 patients). It was assumed that in adynamic-girdling patients dynamic assistance was virtually absent, so the wrapping acted only as a passive constraint wall.</AbstractText>The two groups were comparable for sex, age, dilated cardiomyopathy cause, New York Heart Association class, and left ventricular ejection fraction at the start of the demand protocol period. After a mean duration of follow-up of 41.4 +/- 21.1 months (range, 23 to 69 months), the demand dynamic wrapping group showed improved New York Heart Association class (1.14 +/- 0.34 versus 2.07 + 0.18; p = 0.0004), higher values of left ventricular ejection fraction (34.6 +/- 8.0 versus 26.5 +/- 3.1; p = 0.005) and LD wrap tetanic fusion frequency (38.3 +/- 5.88 versus 24.3 +/- 2.93; p = 0.002), and a better survival (85.7% versus 28.6%; p = 0.037) than the adynamic-girdling group.</AbstractText>Demand dynamic wrapping offers good results in terms of fewer cardiovascular events and greater survival. When compared with the passive constraint effect of LD muscle, demand dynamic wrapping proved to be more effective.</AbstractText> |
2,089 | Terlipressin infusion in catecholamine-resistant shock. | Catecholamine-resistant shock is not uncommon in intensive care. Bolus dose terlipressin (a vasopressin analogue) has been used successfully in this setting allowing cessation of other vasopressor agents. The relative vasopressin deficiency in combination with the restoration of the vascular tone (by blocking adenosine triphosphate potassium-sensitive channels) by exogenous vasopressin may be the explanation of these beneficial effects. We describe a case report where the use of a continuous terlipressin infusion was associated with a dramatic improvement. To our knowledge there have been no previous reports of the use of terlipressin by continuous infusion for the treatment of catecholamine-resistant shock. |
2,090 | General anesthesia for patients with automatic implantable cardioverter defibrillator in place--a case report. | Automatic implantable cardioverter defibrillator (AICD) was commercially available for use in patients with malignant ventricular tachycardia and ventricular fibrillation since its meeting with FDA approval in 1985. The number of AICD implantation has increased year by year worldwide. It was allowed to be used in clinical setting in Taiwan by the Department of Health in April 1997. Physicians may come across patients with an implanted AICD undergoing surgery unrelated to cardiac issues more frequently. It is also a new challenge to anesthesiologists who must make pre-operative evaluation, maintenance during operative period and post-operative re-evaluation of the AICD function. We bring forward here for discussion a 72-year-old male patient who underwent non-cardiac surgery with AICD implantation under general anesthesia. The anesthetic precautions of patients with the device are also touched. |
2,091 | Peroxynitrite in reperfusion arrhythmias and its whole blood chemiluminescence results. | The aims of the present study were to investigate the effects of exogenous peroxynitrite (ONOO(-)) on reperfusion arrhythmias in anaesthetized rats, and to detect endogenous and exogenous ONOO(-)-induced chemiluminescence (CL) signals in rat whole blood, which was collected during baseline and in the first minute of reperfusion. ONOO(-) infusion in ischemia/reperfusion (I/R) applied groups caused significant decreases in mean arterial pressure (MAP) and heart rate (HR). Ventricular fibrillation (VF) incidences in the vehicle, ONOO(-), and dec-ONOO(-) infused groups were 63, 100, and 20%, respectively. In control group CL signal was 136+/-34mV during the resting period and was increased to 336+/-57mV with reperfusion. Also, the effects of SOD+CAT, L-NAME and urate were investigated. Ventricular tachycardia (VT) incidence was decreased significantly in SOD+CAT and urate; VF incidence was decreased significantly in SOD+CAT applied groups. CL signals were inhibited with SOD+CAT, L-NAME, and urate. Exogenous ONOO(-) infusion during I/R was also investigated. CL signal in exogenously ONOO(-) infused group is increased 423% during reperfusion. Only urate infused group VF incidence was decreased significantly. CL signals of ONOO(-) infused groups were inhibited by SOD+CAT, L-NAME, and urate. Based on the results of the current study, ONOO(-) seems to be one of the key mediators of reperfusion arrhythmias in anaesthetized rats. |
2,092 | Novel approaches to identifying antiarrhythmic drugs. | Currently, device therapy with implantable cardioverter-defibrillators is the only proven effective therapy for sudden cardiac death. However, new insights into the mechanisms of ventricular fibrillation, particularly the role of dynamic factors that cause wave instability, are providing conceptual advances toward developing effective new pharmacotherapy. |
2,093 | Review of the current management of atrial fibrillation. | Atrial fibrillation (AF) is the most common sustained arrhythmia. Its prevalence is increasing and accordingly, so is its burden on healthcare systems throughout the world. The pathophysiology of AF is complex and poorly understood, which of itself presents a major challenge to the management of this important condition. AF is associated with increased morbidity and mortality, particularly in patients with underlying left ventricular dysfunction. Once AF occurs, it is often difficult to 'cure' and as such, the major focus of therapy is currently divided essentially between a rate control strategy and a need to revert to and maintain sinus rhythm. Both approaches seek to minimise the associated symptoms and complications. Over the past two decades, numerous pharmacological approaches to the management of AF have been employed, many of which have been shown to be relatively ineffective or confounded by major complications. Accordingly, recent research and interest has focused on non-pharmacological electrophysiological therapies to either cure AF or improve symptoms. This review summarises the current approaches to the management AF and provides some new insights into emerging therapies for this common clinical problem. |
2,094 | A case of sick sinus syndrome that developed torsades de pointes, pacing failure and sensing failure during administration of bepridil. | A 65-year-old Japanese woman was admitted to hospital because of palpitations and faintness. She was diagnosed as having sick sinus syndrome and a permanent pacemaker was therefore implanted. Administration of bepridil (200 mg daily) was started for prevention of atrial flutter and fibrillation after PM implantation. On the twenty-fifth day of Bpd therapy, she developed recurrent syncope, ECG showed QT prolongation. torsades de pointes, and sensing failure. Electrical defibrillation (DF) was performed for ventricular fibrillation or ventricular tachycardia. It was presumed that Bpd had caused not only proarrhythmia but also a transient decrease in the amplitude of ventricular activation at the site of the pacing lead, as the sensing level was gradually restored after the drug was ceased and her plasma concentrations of Bpd decreased. It is also believed that DF had caused a sustained increase in pacing threshold because she developed pacing failure after DF and her pacing threshold had not returned to its prior level although the blood levels of Bpd had been below the minimum detectable level. Although it is well known that torsades de pointes occasionally develops in association with Bpd therapy, it is less evident that pacing and sensing failure may develop in association with Bpd therapy. This case report suggests that we should be aware of this possible outcome when employing Bpd and pacemaker implantation as combination therapy. |
2,095 | Medical devices: cardiovascular devices: reclassification of the arrhythmia detector and alarm. Final rule. | The Food and Drug Administration (FDA) is reclassifying arrhythmia detector and alarm devices from class III to class II (special controls). This device is used to monitor an electrocardiogram (ECG) and to produce a visible or audible signal or alarm when an atrial or ventricular arrhythmia occurs. An atrial or ventricular arrhythmia occurs during a premature contraction or ventricular fibrillation. FDA is reclassifying this device based on new information contained in reclassification petitions regarding the device submitted by the Health Industry Manufacturers Association (HIMA) (now known as Advamed), Quinton Instrument Co., and Zymed Medical Instrumentation. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for this device. FDA is taking this action under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990 (the SMDA), the Food and Drug Administration Modernization Act of 1997 (the FDAMA), and the Medical Device User Fee and Modernization Act of 2002 (MDUFMA). |
2,096 | [Cardiac bradyarrhythmia ]. | Permanent cardiac pacing was introduced in 1958 and till the end of 70s this method saved lives in particular of the patients with advanced atrioventricular block. The implantation technique has changed from complicated thoracotomy to endovasal approaches. The introduction of physiological AV sequenced atrioventricular pacing marked a significant progress in this field. Acute haemodynamic studies documented positive effect of the atrial contribution. Numerous studies subsequently analyzed the influence of different pacing regimes on total and specific cardiovascular mortality and morbidity. It can be concluded that on the basis of present evidence-based medicine the use of physiological pacing is clearly indicated in the patients with expressed sinus bradycardia and AV block of a higher degree. Atrial pacing remains an ideal solution for the patients with isolated sinus node dysfunction and sufficient atrioventricular conduction capacity. Research is continued in order to clarify how to influence the occurrence of ventricular fibrillation by permanent cardiac pacing including the use of preventive algorithms. This topic has not yet been reliably and unambiguously concluded. Biventricular pacing is currently established and recognized not only for typical indications in cases of bradyarrhythmias but also to solve primary haemodynamic problems in the patients with advanced heart failure and evidence of ventricular dyssynchrony. |
2,097 | [Treatment of ventricular arrhythmias]. | The term ventricular arrhythmia denotes various disorder in the cardiac rhythm--from isolated monomorphic ventricular extrasystoles to ventricular flutter and fibrillation. The choice of therapy of ventricular arrhythmias is primarily based on prognostic aspects. Ventricular tachycardias represent the main cause of sudden cardiac death, which is responsible for more than 60% of all deaths for cardial causes. In the industrially advanced countries the ventricular tachyarrhythmias represent more than 90% of cases based on coronary disease. The prevention of sudden death is directed particularly to prevention and therapy of ischaemic heart disease. The prognostic classification divides ventricular tachycardias into benign, potentially malignant and malignant ones, respectively. The benign arrhythmias do not require therapy. In the malignant (i.e. potentially lethal) ventricular tachyarrhythmias the implantation of cardioverter-defibrillator represents the most efficient treatment. In the largest group of patients with potentially malignant ventricular arrhythmias the present risk-oriented stratification enables a partial identification of persons with markedly increased risk of sudden death. They may be considered for preventive implantation of cardioverter-defibrillator. In some patients the therapeutic effect is reached by application of various therapeutic methods including a combination of pharmacological and non-pharmacological therapy, which also includes catheterization or surgical ablation of the arrhythmogenic substrate. A corresponding attention should be devoted to the basal cardial disease. |
2,098 | [Changes in the ECG in chronic heart failure and after transplantation]. | ECG examination belongs to basic procedures in the care of patients with heart failure. The Euroheart Survey study followed the data and therapy of hospitalized patients with chronic heart failure (CHF) with participation of 116 hospitals from 25 European countries and surveyed documentation of 45,993 patients dismissed from internal wards. A new atrial fibrillation or supraventricular tachycardia affected 25.3% of patients, chronic fibrillation was encountered in 23%. Bradyarrhythmia occurred in 10.8% and pacemaker was applied in 8.5% of patients. Ventricular arrhythmias were present in 8.4%, implantable cardiovertor-defibrillator in 1.5%. Syncope was reported in 15% and the arrhythmic death was described in 1.83%. The patients with heart failure suffer from a high incidence of ventricular arrhythmias. About 40-50% of death events in patients with CHF are estimated to be associated with a sudden death or arrhythmia. Large clinical studies investigate the occurrence of and influence upon the sudden death as indices of therapy. The disorders of rhythm as well defects of ventricular conduction may be the risk factors of survival in patients with CHF. The Italian registry of heart failure includes examinations of 5 517 patients. A complete blockade of the left bundle branch block (LBBB) was present in 25.2% patients, whereas a complete blockade of the right bundle branch block (RBBB) occurred in 6.1%. The patients differed in the CHF cause: the group with LBBB suffered more frequently from dilatative cardiomyopathy, whereas IHD more present more frequently in patients without the blockade. The groups also differed in the severity of the disease. The patients with LBBB had a higher prevalence of heart weakness NYHA III and IV (32.8% and 26.4%, respectively, P < 0.001), lower systolic blood pressure, more frequently third heart sound (34.2% versus 22.2%, P < 0.001), cardiomegaly classified as a cardiothoracic index higher that 0.55 (63.2% versus 55%, P < 0.04). In the course of one-year observation 11.9% of patients died, death being evaluated as sudden in 46%. The one-year mortality in patients those with LBBB was 16.1% in contrast to 10.5% in those who had not suffered from the blockade. A sudden death affected 5.5% of patients in the whole cohort, the frequency being again in LBBB (7.3% vs. 4.9%). The risk further increased with a simultaneous atrial fibrillation. After heart transplantation, ECG is also of importance for revealing an acute rejection. In the bilateral operation technique a direct alteration of the sinus node could be the cause of dysfunction. Various bradyarrhythmias developed in later periods of time. A modification of the operation technique has been used in the last 10 years. The application of bicaval method eliminated brachycardiac complications after heart transplantation. A cardiostimulator proved to be necessary in 5 to 15% of patients when biatrial technique was used, whereas it was virtually not required with the bicaval technique. The blockade the left bundle branch block is an unfavorable prognostic factor in the same way as in CHF, whereas of the right bundle branch block is critical in the heart transplantation. It is supposed to be caused by surgical or thermal damage or it is also associated with different degree of the right ventricular dysfunction and a higher number of rejections. The blockade is also associated with worse one-year survival (74% vs. 92%, P < 0.03).</AbstractText>ECG retains its position even in modern times not only in the diagnosis of conditions responsible for heart failure, in the diagnosis of disorder of rhythm and conduction, but it is also of prognostic value. It also retains its position in the same areas as in heart failure, i.e. in the diagnosis and prognosis in heart transplantation.</AbstractText> |
2,099 | Beta-blockers are effective in congestive heart failure patients with atrial fibrillation. | It is controversial whether or not beta-blockers are effective in patients with congestive heart failure (CHF) who are complicated by persistent atrial fibrillation (AF).</AbstractText>We attempted to determine the potential differences in the efficacy between atrial fibrillation and sinus rhythm in 70 CHF patients with NYHA class II-IV and radionuclide ejection fraction (LVEF) <40% who received metoprolol or carvedilol over 16 weeks.</AbstractText>Left ventricular end-diastolic dimension was decreased in AF group (n=24) 4 weeks (early) and 16 to 48 weeks (late) after introduction of beta-blockers (P<.05, P<.001), but not in the sinus rhythm (NSR) group (n=46). End-systolic dimension was decreased in both the AF group (P<.01, P<.0001) and the NSR group (P<.01, P<.0001). LVEF was increased in both the AF group (P<.0005, P<.0001) and the NSR group (P<.0001, P<.0001) early and late after the therapy. Increase in LVEF by the therapy tended to be higher in the AF group than in the NSR group (P=.056). Plasma brain natriuretic peptide level did not change significantly throughout the observation period, although the level tended to be lowered in the AF group late after introduction of beta-blockers (P=.093).</AbstractText>Because beta-blockers are effective in both NSR and AF patients with CHF, such a mode of therapy should be recommended in patients with AF.</AbstractText> |
Subsets and Splits
No saved queries yet
Save your SQL queries to embed, download, and access them later. Queries will appear here once saved.