Causes and consequences of discontinuation of the implantable cardioverter-defibrillator therapy in non-terminally ill patients

Infection and implantable cardioverter-defibrillator shocks are important contributing factors to discontinuation of cardioverter-defibrillator therapy in non-terminally ill patients. These patients are at a high risk of sudden cardiac death despite continued antiarrhythmic drug therapy.     

Rehospitalization in surviving patients of out-of-hospital ventricular fibrillation (the CASCADE Study). Cardiac Arrest in Seattle: Conventional Amiodarone Drug Evaluation

Surviving patients of out-of-hospital ventricular fibrillation (VF) often need rehospitalization after initial hospital discharge, but little is known regarding the frequency of or reasons for rehospitalization. Rehospitalization was examined in 224 patients enrolled in the Cardiac Arrest in Seattle: Conventional Amiodarone Drug Evaluation (CASCADE) study, a randomized clinical trial comparing amiodarone with other antiarrhythmic drug therapy in survivors of out-of-hospital VF. The annual rate of rehospitalization was 79/100 patients/year; 168 of 224 patients (75%) were hospitalized at least once before censoring or cardiac mortality. Baseline left ventricular ejection fraction was significantly lower in patients who were rehospitalized. Rehospitalization rates were lower in patients randomized to amiodarone therapy and in those with the automatic implantable cardioverter-defibrillator, although neither difference was statistically significant. However, length of stay for the first rehospitalization was shorter for patients with automatic implantable cardioverter-defibrillators (p = 0.005). More than 50% of patients were rehospitalized in the first year after enrollment; 65% with ejection fractions < or = 0.3 were rehospitalized in the first year. Rehospitalization was a frequent occurrence for surviving patients of out-of-hospital VF, particularly in those with low ejection fractions.     

Antiarrhythmic therapies for the prevention of sudden cardiac death

Despite remarkable advances in cardiovascular therapeutics, sudden cardiac death remains a significant problem. In this review, data from clinical trials and other studies on antiarrhythmic therapies have been evaluated in order to determine effective strategies for the prevention of sudden cardiac death in high risk patients. Overall, routine prophylactic use of class I antiarrhythmic agents in high risk patients, mostly survivors of acute myocardial infarction, is associated with increased risk of death [61 trials, 23,486 patients: odds ratio (OR) 1.13; 95% confidence interval (CI) 1.01 to 1.27, p < 0.05]. Conversely, beta-blockers are associated with highly significant reductions in risk of death in postinfarction patients (56 trials, 53,521 patients: OR 0.81; 95% CI 0.75 to 0.87, p < 0.00001). Overall data from the amiodarone trials on high risk patients, including postinfarction patients, patients with congestive heart failure or survivors of cardiac arrest, suggest that this agent is effective in reducing the risk of death (14 trials, 5713 patients: OR 0.83; 95% CI 0.72 to 0.95, p = 0.01) although further studies are needed to better define which types of patients will potentially benefit most from this agent. No benefits were seen with calcium channel blockers (26 trials, 21,644 patients: OR 1.03; 95% CI 0.94 to 1.13, p = NS). The implantable cardioverter-defibrillator is a promising option for high risk patients, but definition of its role awaits the completion of ongoing clinical trials. Since causes of sudden death are heterogeneous, the clinician should pursue a multifactorial approach to its prevention. Primary and secondary prevention of cardiac ischaemia, through the treatment of cardiovascular risk factors and maximising the use of aspirin, beta-blockers, lipid-lowering drugs, and angiotensin converting enzyme inhibitors after acute myocardial infarction, should lead to a future decrease in the incidence of sudden cardiac death.     

The Brevibacterium albidum gene encoding the arginine tRNACCG complements the growth defect of an Escherichia coli strain carrying a thermosensitive mutation in the rnpA gene at the nonpermissive temperature

Antiarrhythmic drug prophylaxis in patients with atrial fibrillation (AF) is associated with a high incidence of arrhythmic recurrence. Uncontrolled studies have suggested that low-dose amiodarone may be superior in terms of efficacy to other antiarrhythmic drugs while having an acceptable side effect profile. The Canadian Trial of Atrial Fibrillation (CTAF) is a 25-center study sponsored by the Medical Research Council of Canada to determine the best treatment strategy to maintain sinus rhythm in patients with persistent or paroxysmal AF. Recruitment began in November 1996 and will continue for 1.5 years. Patients are randomized to receive either low-dose amiodarone or conventional antiarrhythmic drug therapy. Patients assigned to the amiodarone group will receive an oral loading regimen of 10 mg/kg/day during a minimum 14-day period. Patients assigned to conventional antiarrhythmic therapy will receive 1 of 2 agents commonly used in AF prophylaxis: sotalol or propafenone. Drug selection and loading, and electrical cardioversion, if necessary, will be performed within 21 days of randomization. The long-term maintenance dose of amiodarone is 200 mg/day. We have planned a minimum follow-up period of 1 year. The primary end point is the time to the first relapse of AF. Data will be analyzed on an intention-to-treat basis. Secondary outcomes are medication toxicity, mortality, major clinical events, costs of each approach, and quality of life. For the purpose of sample size calculations, it is anticipated that recurrence of AF at 1 year will occur in 50% of patients on conventional treatment compared with 35% in those receiving amiodarone. In order to have an 80% power and a 2-tailed type I error of 0.05, assuming a 15% loss to follow-up rate, a total sample size of 400 patients will be required. A pilot study done at the Montreal Heart Institute has shown that the research protocol is feasible.     

Inferior alveolar nerve function after mandibular osteotomies

Many patients with an implanted cardioverter defibrillator (ICD) also receive antiarrhythmic drug therapy. Although an expanding number of patients are receiving ICD therapy, many will not have received previous antiarrhythmic treatment. For patients with an ICD, infrequent arrhythmias and a low probability of inappropriate device discharges, no antiarrhythmic therapy is required. However, for those patients who require an antiarrhythmic drug, amiodarone is a reasonable first choice because of safety in patients with poor LV function. It may be particularly useful for patients with high density ventricular arrhythmias. However, the interactions between ICDs and antiarrhythmic therapy requires close monitoring in order that patient benefit can be optimised, and this review focuses on those interactions.     

Amiodarone reduces transmural heterogeneity of repolarization in the human heart

OBJECTIVES: The present work was designed to test the effects of amiodarone therapy on action potential characteristics of the three cell types observed in human left ventricular preparations. BACKGROUND: The electrophysiologic basis for amiodarone's exceptional antiarrhythmic efficacy and low proarrhythmic profile remains unclear. METHODS: We used standard microelectrode techniques to investigate the effects of chronic amiodarone therapy on transmembrane activity of the three predominant cellular subtypes (epicardial, midmyocardial [M] and endocardial cells) spanning the human left ventricle in hearts explanted from normal, heart failure and amiodarone-treated heart failure patients. RESULTS: Tissues isolated from the ventricles of heart failure patients receiving chronic amiodarone therapy displayed M cell action potential duration (404+/-12 ms) significantly briefer (p < 0.05) than that recorded in tissues isolated from normal hearts (439+/-22 ms) or from heart failure patients not treated with amiodarone (449+/-18 ms). Endocardial cells from amiodarone-treated heart failure patients displayed longer (p < 0.05) action potential duration (363+/-10 ms) than endocardial cells isolated from normal hearts (330+/-6 ms). As a consequence, the heterogeneity of ventricular repolarization in tissues from patients treated with amiodarone was considerably smaller than in the two other groups, especially at long pacing cycle lengths. CONCLUSIONS: These findings may explain, at least in part, the reduction of ventricular repolarization dispersion and the lower incidence of torsade de pointes observed with chronic amiodarone therapy as compared with other class III agents.     

Bronchodilator response to salbutamol after chronic dosing with salmeterol or placebo

OBJECTIVES: We report the occurrence of cardiac events during long-term follow-up in patients with hypertrophic cardiomyopathy (HCM) after cardioverter-defibrillator implantation. BACKGROUND: The identification of patients at high risk for sudden death and the prevention of recurrence of sudden death in HCM represents a difficult problem. METHODS: We retrospectively analyzed the occurrence of cardiac events during follow-up of 13 patients with HCM who received an implantable cardioverter-defibrillator (ICD) because of aborted sudden death (n = 10) or sustained ventricular tachycardia (n = 3) (group I). Findings were compared with those in 215 patients with an ICD and other structural heart disease or idiopathic ventricular fibrillation (group II). RESULTS: After a mean (+/-SD) follow-up period of 26+/-18 months, 2 of 13 patients in group I received appropriate shocks. The calculated cumulative incidence of shocks was 21% in group I and 66% in group II after 40 months (p < 0.05). We observed a low incidence of recurrence of ventricular tachycardia/fibrillation during follow-up in patients with HCM. No deaths occurred. CONCLUSIONS: Our data suggest that ventricular tachyarrhythmias may not always be the primary mechanism of syncope and sudden death in patients with HCM. The ICD seems to have a less important impact on prognosis in patients with HCM than in patients with other etiologies of aborted sudden death.     

Complications associated with pectoral cardioverter-defibrillator implantation: comparison of subcutaneous and submuscular approaches. Worldwide Jewel Investigators

OBJECTIVES: The aim of this study was to compare complications in a large cohort of patients undergoing pectoral cardioverter-defibrillator implantation with a subcutaneous or submuscular approach. BACKGROUND: Pectoral placement of implantable cardioverter-defibrillator (ICD) pulse generators is now routine because of downsizing of these devices. subcutaneous implantation has been advocated by some because it is a simple surgical procedure comparable to pacemaker insertion. Others have favored submuscular insertion to avoid wound complications. These surgical approaches have not been compared previously. METHODS: The subjects for this study were 1,000 consecutive patients receiving a Medtronic Jewel ICD at 93 centers worldwide. Cumulative follow-up for all patients was 633.7 patient-years, with 64.9% of patients followed up for > or = 6 months. The complications evaluated were erosion, pocket hematoma, seroma, wound infection, dehiscence, device migration, lead fracture and dislodgment. RESULTS: Subcutaneous implantation was performed in 604 patients and submuscular implantation in the remaining 396. The median procedural times were shorter for subcutaneous implantation (p = 0.014). In addition, the cumulative percentage of patients free from erosion was greater for subcutaneous implantations (p = 0.03, 100% vs. 99.1% at 6 months). However, lead dislodgment was more common with subcutaneous implantations (p = 0.019, 2.3% vs. 0.5% at 6 months) and occurred primarily during the first month postoperatively. Overall, there were no significant differences in cumulative freedom from complications between groups (4.1% vs. 2.5%, p = 0.1836). CONCLUSIONS: Subcutaneous pectoral implantation of this ICD can be performed safely and has a low complication rate. This approach requires a simple surgical procedure and, compared with the submuscular approach, is associated with shorter procedure times and comparable overall complication rates. However, early follow-up is important in view of the increased lead dislodgment rate.     

Prediction of outcome of patients with life-threatening ventricular arrhythmias treated with automatic implantable cardioverter-defibrillators using SPECT perfusion imaging

BACKGROUND: In the present study, we examined the predictors of outcome of 103 patients with coronary artery disease and left ventricular dysfunction who had life-threatening ventricular arrhythmias and were treated with implantable cardioverter-defibrillators with the use of single-photon emission computed tomography (SPECT). METHODS AND RESULTS: During a mean follow-up of 29 months, there were 29 cardiac deaths. In comparison with patients who died, survivors had less diabetes mellitus (45% versus 19%, P < .007), higher left ventricular ejection fraction (23 +/- 9% versus 27 +/- 11%, P = .04), and fewer perfusion defects as determined with stress SPECT (15 +/- 5 versus 12 +/- 5, P < .004). Most of the perfusion defects were fixed, indicative of scarring; the extent of reversible defects did not differ (2 +/- 3 in survivors and 3 +/- 4 in nonsurvivors). Multivariate Cox survival analysis identified the number of fixed defects as the only independent predictor of death (chi 2 = 10, P = .002). There were six deaths among 42 patients (14%) with < 8 fixed defects compared with 23 deaths among 61 patients (38%) with > or = 8 defects (P = .005). The 4-year survival was better in patients with < 8 segmental fixed defects than in those with > or = 8 fixed defects (80% versus 36%) (chi 2 = 8, P = .005). CONCLUSIONS: The myocardial perfusion pattern is an important determinant of outcome in patients with life-threatening ventricular arrhythmias who are treated with a implantable cardioverter-defibrillator. The extent of scarring separates patients into high- and low-risk groups with a 2.7-fold difference in death rate.     

Misplacement of a transvenous lead from an implantable cardioverter-defibrillator into the left ventricle via a patent foramen ovale

HISTORY AND CLINICAL FINDINGS: 24-hour ECG monitoring in a 64-year-old man revealed self-limited (< 30 s) ventricular tachycardias (VT) of > 200/min. He had triple-vessel coronary artery disease with both anterior and posterior wall infarctions treated by three aortocoronary venous grafts. Physical examination was unremarkable except for a well healed thoracotomy scar. INVESTIGATIONS: Programmed ventricular stimulation induced prolonged monomorphic VT of 320 beats/min, despite aminodarone treatment. Left-heart catheterization demonstrated the three patent aortocoronary grafts and a left-ventricular ejection fraction of only 20%. TREATMENT AND COURSE: Because of the inducible and prolonged VT, despite antiarrhythmic treatment with amiodarone, a cardioverter-defibrillator was implanted (ICD). During threshold measurements of the pacemaker integrated into the ICD the pacemaker impulse was noted to produce a right bundle branch block pattern, the ICD lead having erroneously been placed in the left ventricle via a patent foramen ovale. The lead was left in place, because the ICD was functioning well and lead removal with the possible need of a thoracotomy carried a high risk. CONCLUSION: Extreme caution is needed to avoid malpositioning an implantable cardioverter-defibrillator. If the lead tip is unwittingly fixed in the left ventricle but functions well it should be left in place under prophylactic anticoagulation, because of the potentially high risk of its operative removal.     

Predictors of arrhythmic death and cardiac arrest in the ESVEM trial. Electrophysiologic Study Versus Electromagnetic Monitoring

BACKGROUND: The purpose of this study was to determine if the presenting ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation/cardiac arrest) predicted the type of arrhythmia recurrence in patients treated with antiarrhythmic drugs. METHODS AND RESULTS: In the previously reported Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, there were 486 patients who were randomized to antiarrhythmic drug testing guided by electrophysiological study or by ambulatory ECG monitoring. Use of a defibrillator (implantable cardioverter-defibrillator, ICD) without stored electrograms among 81 patients precluded determination of the type of arrhythmia recurrence; thus these patients were censored at the time of ICD implantation. Of the 486 patients, 381 presented with ventricular tachycardia and 105 with cardiac arrest. Over a 6-year follow-up period, 285 of the 486 patients had an arrhythmia recurrence; of these, 97 had an arrhythmic death or cardiac arrest as a first recurrence. In the current analysis, all 129 arrhythmic deaths/cardiac arrests that occurred any time during follow-up were evaluated as end points. CONCLUSIONS: Although univariate analysis suggested that there was an association between the presenting arrhythmia and outcome, multivariate analysis failed to substantiate the predictive value of the presenting arrhythmia. Left ventricular ejection fraction was the single most important predictor of arrhythmic death or cardiac arrest. This information may be an important factor in deciding whether to advise ICD therapy.     

The concurrent implantation of a last-generation automatic defibrillator and a 2-chamber pacemaker

BACKGROUND: Potentially lethal interactions between concomitantly implanted pacemaker and automatic first-generation cardioverter-defibrillator have been reported. We therefore evaluated the reliability and safety of simultaneous implantation of dual-chamber pacemakers with a fourth generation cardioverter-defibrillator incorporating an improved arrhythmia detection system. METHODS: Concomitant implantation of an automatic cardioverter defibrillator and a dual-chamber pacemaker was performed in four patients for malignant tachyarrhythmias and symptomatic bradycardia. Two Jewel 7219C and two Micro Jewel 7223 (Medtronic Inc.) implantable cardioverter defibrillators were connected to an endocardial lead (Medtronic Mod. 6936). In 2 patients with a previously implanted cardioverter-defibrillator, the pacemaker was connected to bipolar atrial and ventricular leads. In the 2 patients who already had a dual-chamber pacemaker, the unipolar pacing leads implanted previously were used. At the time of implantation of the second device, interaction testing was performed evaluating ventricular fibrillation detection during high-output asynchronous pacing. Testing for malfunctions, reprogramming or variations of pacing thresholds of the pacemakers after electric shocks was also carried out. Moreover, intracavitary signals, stimulation thresholds and electrical therapies delivered were evaluated during follow-up. RESULTS: During interaction testing, induced ventricular fibrillation was detected, with no delay, in 4/4 cases (100%). After a mean follow-up of 6.3 +/- 5 months (range 2-13), 5 shocks for ventricular fibrillation, 10 shocks for fast ventricular tachycardia and 72 antitachycardia pacings were delivered. All these electrical therapies were considered appropriate. No symptomatic sustained tachyarrhythmia remained undetected. CONCLUSIONS: These data suggest that concomitant implantation of a fourth-generation automatic cardioverter-defibrillator and a dual-chamber pacemaker using either unipolar or bipolar leads can be performed safely. Extreme caution and rigorous interactions testing is nevertheless advised when considering this device combination.     

Treatment of amiodarone-induced hyperthyroidism by carbimazole with maintenance of amiodarone

The authors report the case of a patient treated with amiodarone for syncopal ventricular tachycardia complicating idiopathic dilated cardiomyopathy in whom symptomatic hyperthyroidism led to a discussion of the different therapeutic options available in this type of case. Neomercazole treatment was prescribed with success enabling maintenance of the antiarrhythmic drug. The reputation of inefficacy of carbimazole should be reconsidered ; high dose therapy should probably be tried in patients with hyperthyroidism when withdrawal of the antiarrhythmic drug does not seem to be possible.     

Favorable results of implantable cardioverter-defibrillator implantation in patients older than 70 years

BACKGROUND: The clinical results of implantable cardioverter-defibrillator (ICD) implantation in the elderly have received limited documentation. As the longevity of the U.S. population has increased, so has the need for ICD implantation in the elderly. We evaluated the efficacy and outcome of ICD implantation in elderly patients (>70 years) compared with younger patients. METHODS: The case records of all consecutive patients who underwent ICD implantation at our institution between 1986 and 1994 were reviewed. Of a total of 238 patients, 78 patients were 70 years of age or older and 160 patients were younger than 70 years of age. RESULTS: The mean age of the younger group was 58 years and that of the elderly group was 74 years. There were no statistical differences in the presence of coronary artery disease, left ventricular systolic function, the inducibility of arrhythmias, or the history of sudden cardiac death. The hospital morbidity rate was similar in both groups (6.9% in the younger group and 7.7% in the elderly group; p = not significant). The operative mortality rate was 1.9% for the younger group and 1.3% for the elderly group (p = not significant). At a mean follow-up of 33 +/- 26 months, Kaplan-Meier survival curves demonstrated similar survival rates, with 93%, 82%, and 65% of the patients alive at 1, 3, and 6 years, respectively. CONCLUSIONS: Implantable cardioverter-defibrillator implantation was equally effective in the treatment of patients older than 70 years as in younger patients. No differences in theoretic survival or morbidity were observed.     

Radiofrequency ablation of type I atrial flutter: combination of electrophysiological and anatomical techniques

Atrial flutter type I (FLA) is one of the most common arrhythmias found in clinical practice. Reentry into the right atrium (AD) is the mechanism of this arrhythmia. The reentry mechanism has critical sites where radiofrequency (RF) can act blocking the circuit. Both, electrophysiological and anatomical approaches using RF to FLA have demonstrated a success rate above 80%. Our group combined both techniques treating 35 patients with FLA type I (22 men and 13 women), with mean age of 40.8 +/- 15 years old (range 9-70). In 21 patients (60%) this arrhythmia was associated with cardiopathy. All patients had failed to respond to different antiarrhythmic therapy. The success rate was 82.8% (29/35). When compared failure vs success we observed that patients who failed were older (51.8 vs 38.5 years old, p < 0.05), had structural cardiopathy (83.3% vs 55.1%, p = NS), had FLA type I with P waves with shorter cycle length (195 vs 254 ms, p = 0.052), had the arrhythmia chronically (129.6 vs 68.1 month, p = NS), had great left atrium diameter (41.2 vs 36.7 mm, p = 0.052) and frequently had been associated with atrial fibrillation (33.3% vs 3.4%, p = 0.02). There were no complications. Six (20.6%) patients reverted to FLA. We followed our patients during mean time 8.37 +/- 8.8 months (1-36). Our results support the notion that FLA type I can be treated with high percentage of success and low risk of complications when both RF techniques are combined. Our predictors of failure were: gender and associated atrial fibrillation (p < 0.05). We conclude that RF is the treatment of choice in every patient with FLA type I who had failed to antiarrhythmic therapy. We recommend RF as soon as FLA has been diagnosed because the probability of success is higher in such instances.     

The implantable cardioverter/defibrillator

Despite all advances in the diagnosis and therapy of cardiovascular diseases, the mortality from malignant ventricular tachyarrhythmias is still a major health problem. In addition to established therapeutic strategies in the prevention of sudden cardiac death such as antiarrhythmic drug treatment, catheter ablation or antiarrhythmic drug treatment, cardioverter/defibrillator was introduced to clinical practice in 1980. The number of 50,000 overall implants reflects the current clinical status of the therapy with implantable cardioverter/defibrillators. Significant technical improvements in the defibrillator therapy may contribute to an increase in therapy acceptance. These advances include the introduction of nonthoracotomy lead systems, enhanced defibrillation efficacy, full programmable devices providing tiered electrical therapy, improved diagnostic Holter functions and enhanced arrhythmia detection algorithms. The major present goals of defibrillator therapy are detection and termination of malignant ventricular tachyarrhythmias, prevention of sudden cardiac death, reduction in patient's mortality and improvement in quality of life. The efficacy and safety of defibrillator therapy to prevent sudden arrhythmic death has been proven in several large clinical investigations In patients with this device the annual sudden cardiac death mortality is < 2% even in high-risk patient populations. Compared to sudden cardiac death rate there is a much higher rate of overall cardiac mortality because a defibrillator is not able to prevent nonarrhythmic cardiovascular deaths. There is a clinical impression that cardiovascular mortality is lower in patients treated with an implantable cardioverter/defibrillator compared to patients treated with other therapies. However, there are no results from controlled studies providing scientific evidence that defribillator therapy can decrease overall cardiovascular mortality.(ABSTRACT TRUNCATED AT 250 WORDS)     

Treatment of paroxysmal ventricular tachycardia]

The authors present a retrospective evaluation of the risk stratification and therapy of 53 patients with ventricular tachycardia. They present the diagnostical algorithm used for the detection of risk of sudden death. The most frequently used drug in the set of patients was amiodarone in monotherapy or in combination with other drugs. Sotalol was used for both, its antiarrhythmic nature, and for its ability to reduce the defibrillation threshold in patients with an implanted automatic implantable cardiovertor-defibrillator (AICD). Antiarrhythmic drugs of class I in monotherapy were used in patients with non-coronary causes of ventricular tachycardia and with normal left ventricular function. The authors, on the basis of sudden death of three patients with low ejection fraction of the left ventricle which were recorded even despite Holter apparatus and electophysiologically confirmed supression of ventricular tachycardia, recommend to consider in this group of patients the primary AICD implantation. (Tab. 4, Fig. 2, Ref. 13.)     

Comparison of S(-)-bupivacaine with racemic (RS)-bupivacaine in supraclavicular brachial plexus block

Control of heart rate in critically ill patients who develop atrial fibrillation or atrial flutter can be difficult. Amiodarone may be an alternative agent for heart rate control if conventional measures are ineffective. We retrospectively studied intensive care unit patients (n = 38) who received intravenous amiodarone for heart rate control in the setting of hemodynamically destabilizing atrial tachyarrhythmias resistant to conventional heart rate control measures. Atrial fibrillation was present in 33 patients and atrial flutter in 5 patients. Onset of rapid heart rate (mean 149 +/- 13 beats/min) was associated with a decrease in systolic blood pressure of 20 +/- 5 mm Hg (p <0.05). Intravenous diltiazem (n = 34), esmolol (n = 4), or digoxin (n = 24) had no effect on heart rate, while reducing systolic blood pressure by 6 +/- 4 mm Hg (p <0.05). The infusion of amiodarone (242 +/- 137 mg over 1 hour) was associated with a decrease in heart rate by 37 +/- 8 beats/min and an increase in systolic blood pressure of 24 +/- 6 mm Hg. Both of these changes were significantly improved (p <0.05) from onset of rapid heart rate or during conventional therapy. Beneficial changes were also noted in pulmonary artery occlusive pressure and cardiac output. There were no adverse effects secondary to amiodarone therapy. Intravenous amiodarone is efficacious and hemodynamically well tolerated in the acute control of heart rote in critically ill patients who develop atrial tachyarrhythmias with rapid ventricular response refractory to conventional treatment. Cardiac electrophysiologic consultation should be obtained before using intravenous amiodarone for this purpose.     

Okadaic acid-stimulated degradation of p35, an activator of CDK5, by proteasome in cultured neurons

BACKGROUND: Implantable cardioverter-defibrillators have been infrequently used in children as therapy for resuscitated sudden death and syncope due to ventricular arrhythmias unresponsive to antiarrhythmics. METHODS: The medical records of 5 children with implantable cardioverter-defibrillators were retrospectively reviewed. All patients had experienced syncope and 3 (60%) an out-of-hospital cardiac arrest. Underlying pathology included hypertrophic cardiomyopathy in 2, long QT syndrome in 2, and ventricular arrhythmia after remote repair of congenital heart disease in 1. Open thoracotomy with epicardial lead placement and transvenous endocardial approaches were used. RESULTS: There was no early or late mortality in the 5 pediatric patients undergoing implantable cardioverter-defibrillator placement. Postoperative complications occurred more frequently when open thoracotomy was used for placement. At mean follow-up of 34 months, 4 of the 5 (80%) have received shocks. CONCLUSIONS: Implantable cardioverter-defibrillator is a safe and reliable therapy for children with resuscitated sudden death and syncope due to ventricular tachycardia unresponsive to antiarrhythmics. Transvenous lead placement lowers morbidity and hospital length of stay.     

The diagnostic value of symptoms and signs in childhood abdominal pain

Amiodarone is a benzofuran derivative with a chemical structure similar to thyroxine. Originally introduced to treat angina pectoris, amiodarone was found to have antiarrhythmic properties, and in 1985, was approved in the United States for treatment of life-threatening ventricular arrhythmias. It is now used for various ventricular and supraventricular arrhythmias refractory to conventional first-line medications, and as a result, side effects have been observed with increased frequency. The most severe and potentially life-threatening of these side effects is the development of pulmonary toxicity. Typically, amiodarone pulmonary toxicity (APT) is manifested by acute pneumonitis and chronic fibrosis. Amiodarone-associated hemoptysis (AAH) is a rare occurrence. The authors describe a case of AAH successfully treated with cessation of drug and steroid therapy.