Pharmacologic and pharmacokinetic profile of class III antiarrhythmic drugs.

Cardiac arrhythmias frequently respond only to drugs that have as their predominant electrophysiologic effect the prolongation of repolarization and refractoriness. According to the Singh-Vaughan Williams classification, these drugs are known as class III agents. In the last few years, interest has increased in the development of class III antiarrhythmic drugs as alternatives to sodium channel blocking agents, which mainly affect cardiac conduction.

Regression of left ventricular hypertrophy with captopril restores normal ventricular action potential duration, dispersion of refractoriness, and vulnerability to inducible ventricular fibrillation.

Background: Left ventricular hypertrophy (LVH) is associated with multiple cellular electrophysiological abnormalities, susceptibility to ventricular arrhythmias, and an increased risk of sudden death. Several pharmacological therapies have been shown to produce regression of hypertrophy, but the value of regression is unclear. The present study examines whether pharmacological regression of LVH has effects on the susceptibility to ventricular arrhythmia or the cellular electrophysiological abnormalities of LVH.

Air leaking through the mouth during nocturnal nasal ventilation: effect on sleep quality.

Air leaking through the mouth has been reported in kyphoscoliotic patients receiving nasal ventilation via volume-limited ventilators. This study accessed the frequency of occurrence and effect on sleep quality of air leaking through the mouth during nocturnal nasal ventilation in patients with chest wall and neuromuscular disease using pressure-limited ventilation. Overnight and daytime polysomnography was performed in six stable experienced users of nocturnal nasal noninvasive positive-pressure ventilation (NPPV) who had chronic respiratory failure due to neuromuscular disease or chest wall deformity.

Continuous retrograde cardiac perfusion decreases risk of reoperative coronary artery bypass grafting.

Embolization of atheromatous debris from old saphenous vein grafts is a major factor that increases the risk of reoperative coronary artery bypass grafting (CABG) when compared with primary CABG. To decrease this risk, a technique consisting of minimal dissection of the heart prior to cross clamping, continuous retrograde coronary sinus perfusion with 32 degrees C blood, and temporary posterior cardiac interventricular vein occlusion, during which time all dissection and anastomoses are performed, was evaluated prospectively in 130 consecutive patients from January 2, 1991, through February 28, 1995. This group was compared with a cohort of 1107 patients undergoing primary CABG performed concurrently.

Intravenous amiodarone.

Intravenous amiodarone was approved in 1995 for the treatment of malignant and resistant ventricular arrhythmia. Although it is an "old drug," much has been learned recently about this complex drug and its application in a variety of cardiac arrhythmias. The objectives of this review were to summarize what is known about intravenous amiodarone, including its pharmacologic and electrophysiologic effects, to review its efficacy for the treatment of patients with highly malignant ventricular arrhythmia and to provide specific information about its clinical use for this and other indications.

Effectiveness of digitalis with or without acebutolol in preventing atrial arrhythmias after coronary artery surgery.

In this study, a beta-adrenergic blocker in combination with digoxin provided marginal protection against atrial fibrillation/flutter after coronary artery surgery. The economic comparison of patients who did and did not develop atrial fibrillation/flutter indicates that prevention of these arrhythmias can have a significant impact on length of hospital stay and cost of this common surgical procedure.

Safety and risk/benefit analysis of ibutilide for acute conversion of atrial fibrillation/flutter.

Safety data were reviewed from several controlled clinical trials of ibutilide, a new class III antiarrhythmic drug recently approved for the acute interruption of atrial fibrillation and flutter. Noncardiovascular adverse effects of ibutilide were similar in frequency to those with placebo. Cardiovascular adverse effects occurred in 24.

Monomorphic right ventricular tachycardia in a patient with mitral valve prolapse.

A patient with mitral valve prolapse and symptomatic ventricular ectopy underwent an electrophysiological study during which a sustained monomorphic ventricular tachycardia with a left bundle branch block/right axis deviation morphology was induced. This morphology was replicated by pace mapping at the right ventricular outflow tract. To the best of our knowledge, this finding has not been previously described and suggests that the association between ventricular arrhythmias and mitral valve prolapse may not necessarily be causal.

Nocturia. A rarely recognized symptom of sleep apnea and other occult sleep disorders.

Background: Nocturia, awakening from sleep to urinate, is a common symptom in a variety of medical disorders and in the elderly. Awakening from sleep as a result of nocturia is thought to be secondary to a sensation of urinary urgency resulting from an overextended bladder. Nocturia-related awakenings cause significant sleep disruption and fatigue in elderly patients and are correlated with an increased number of falls at night.

Atrial fibrillation, anticoagulation, and stroke.

There is a demonstrated statistical association between atrial fibrillation, rheumatic valvular disease, and embolic stroke. This article assesses the results of 6 major clinical trials (AFASAK, BAATAF, SPINAF, SPAF [parts I and II], CAFA and EAFTA--see text for trial names). Multivariate analysis revealed 4 independent clinical features that identified patients with atrial fibrillation at an increased risk for stroke: hypertension, increasing age, previous transient ischemic attack, and diabetes mellitus.

Randomized, double-blind comparison of intravenous amiodarone and bretylium in the treatment of patients with recurrent, hemodynamically destabilizing ventricular tachycardia or fibrillation. The Intravenous Amiodarone Multicenter Investigators Group.

Background: After several days of loading, oral amiodarone, a class III antiarrhythmic, is highly effective in controlling ventricular tachyarrhythmias; however, the delay in onset of activity is not acceptable in patients with immediately life-threatening arrhythmias. Therefore, an intravenous form of therapy is advantageous. This study was designed to compare the safety and efficacy of a high and a low dose of intravenous amiodarone with bretylium, the only approved class III antiarrhythmic agent.

Transient ischemic attacks and minor stroke during sleep. Relationship to obstructive sleep apnea syndrome.

Background: It is reported that 13% to 44% of all cerebrovascular accidents (CVAs) occur during sleep. In addition to other well-known risk factors, snoring, sleep apnea, obesity, and daytime sleepiness have been shown to significantly increase the risk of stroke. We describe two cases that support the statistical relationship between snoring, sleep apnea, and CVA during sleep.

Night terrors in an adult precipitated by sleep apnea.

Parasomnias are generally described as disorders of arousal that arise out of stage 3 and 4 nonrapid eye movement (NREM) sleep without identifiable cause. We present a case of a 35-year-old man who during nasal continuous positive airway pressure (nCPAP) treatment for severe obstructive sleep apnea experienced an intense night terror triggered by a residual obstructive apnea during rebound deep sleep. The role of rebound deep sleep was thought to be essential in creating a state of sleep with a high arousal threshold hypothesized to be important for the occurrence of parasomnias.

Parenteral antiarrhythmics for life-threatening ventricular arrhythmias.

The acute management of life-threatening ventricular tachyarrhythmias often includes the use of parenteral antiarrhythmics. There are a number of agents currently available for this purpose. They are used to suppress inducible monomorphic ventricular tachycardia during programmed electrical stimulation, they terminate spontaneous sustained ventricular tachycardia, and prevent ventricular fibrillation in the setting of an acute myocardial infarction.

Ramp abuse. A novel form of patient noncompliance to administration of nasal continuous positive airway pressure for treatment of obstructive sleep apnea.

Administration of nasal continuous positive airway pressure (NCPAP) is the treatment of choice for most patients with obstructive sleep apnea. Many patients experience side effects with NCPAP use, and the compliance rate is reported to vary between 46-89%. The ramp is a device found on many NCPAP machines that resets the pressure to 3 cm H2O and then slowly increases the pressure to the prescribed pressure over a period of up to 45 min.

Outcome of patients with nonsustained ventricular tachycardia and severely impaired ventricular function who have negative electrophysiologic studies.

Twenty-nine consecutive patients with a prior myocardial infarction, severely reduced left ventricular ejection fraction (26% +/- 8%), and asymptomatic nonsustained ventricular tachycardia were enrolled in a prospective trial. After a negative programmed electric stimulation study (3 extrastimuli at 2 sites with 2 drive trains), the 26 men and 3 women (mean age 71) were monitored for a mean of 13 months without antiarrhythmic drug therapy. Five patients died suddenly or had sustained ventricular tachycardia; three others had a cardiac, nonarrhythmic death.

Effect of left ventricular hypertrophy and its regression on ventricular electrophysiology and vulnerability to inducible arrhythmia in the feline heart.

Background: Left ventricular hypertrophy (LVH) is associated with an increased risk of death, susceptibility to ventricular arrhythmia, and multiple electrophysiological abnormalities. The purpose of the present study was to determine whether the susceptibility to arrhythmia and electrical abnormalities persists after regression of hypertrophy in an animal model of LVH.

Methods And Results: We placed constricting bands on the ascending aorta of cats (n = 9) or performed sham operations (n = 9).

Does routine use of aortic ultrasonography decrease the stroke rate in coronary artery bypass surgery?

Purpose: The purpose of this study is to determine whether the routine use of intraoperative surface aortic ultrasonography decreases the stroke rate in coronary artery bypass graft surgery (CABG).

Methods: One hundred ninety-five consecutive patients undergoing CABG between July 1, 1992, and June 30, 1993 (study group), were evaluated by intraoperative surface aortic ultrasonography. Based on information obtained, changes in the operative technique were made in an effort to decrease the incidence of embolic stroke from unsuspected atherosclerotic disease of the ascending aorta.

Evidence for a reexcitability gap in man after treatment with type I antiarrhythmic drugs.

The intention of this study was to determine whether type IA antiarrhythmic drugs cause a disparity between refractoriness and repolarization, and if so, its magnitude. We simultaneously measured monophasic action potential duration (MAPD) and effective refractory period (ERP) at a right ventricular site in 11 patients without overt right ventricular disease. The pacing protocol, which included sinus rhythm and a 600 and 400 msec cycle length of ventricular drive, was performed at baseline and after the intravenous administration of 15 mg/kg of procainamide in nine patients, and of 10 mg/kg of quinidine in two patients.

Prevention of retrograde cardioplegia catheter displacement.

The most frequent catheter-related complication of retrograde cardioplegia, in our experience, has been catheter displacement. An easily placed coronary sinus snare that maintains proper retrograde catheter position is described.

Use of venous fistula technique for intraoperative cardiac hemorrhage.

We describe an innovative technique to control hemorrhage after right atrial wall reconstruction in a patient with primary angiosarcoma. At the time of surgery, the tumor was found to involve all of the free wall of the right atrium and a superficial layer of the right ventricle. A pericardial patch was used to reconstruct the right atrial wall; however, there was diffuse coagulopathy with bleeding from the anastomoses and remaining tumor.

Contact diode laser microvascular anastomosis.

Contact diode laser microvascular anastomosis appears to be a valuable technique for anastomosing small arteries and veins. Significantly less foreign body reaction and markedly decreased operative time has been shown to be a major advantage of using contact diode laser technology. The authors have found that contact diode laser anastomosis can be performed in vessels as small as 1 mm in size using a 200-microns flat tip synthetic sapphire probe.