Treatment Of Atrial Tachyarrhythmias Research Articles

Verapamil infusions in the treatment of atrial tachyarrhythmias.

Ten patients with symptomatic atrial tachyarrhythmias were treated with an iv verapamil bolus (mean 8.5 mg) followed by a continuous verapamil infusion (mean dose 9.4 mg/h). The infusions were titrated to ventricular rate and continued for an average of 20 h, until oral therapy could be instituted. All patients had a significant, sustained reduction in ventricular rate during the infusion, without a significant reduction in mean arterial pressure. Although one patient complained of dizziness after 8 h of infusion therapy, the regimen was generally well tolerated and no patient had clinical worsening of heart failure. These preliminary data suggest that continuous verapamil infusions can safely and effectively control ventricular rate in patients with rapid atrial tachyarrhythmias, until oral medications can be started.

Amiodarone for tachyarrhythmias: pharmacology, kinetics, and efficacy.

Amiodarone, although widely studied in Europe, is a recent addition to the investigational antiarrhythmics being used in the U.S. Pharmacologically, its primary cardiac effects are to increase coronary artery blood flow, increase the effective refractory period, and produce an atropine-resistant bradycardia. Amiodarone is incompletely (approximately 50 percent) and slowly (peak serum concentration approximately 6 h) absorbed. With chronic administration, it deposits both in adipose tissue and in organs with high blood perfusion. It has an apparent elimination half-life of 15-45 days, which presents unique dosing problems. The apparent therapeutic range is 0.6-3 microgram/ml. Amiodarone is 85-95 percent effective in the treatment of atrial tachyarrhythmias and 70-80 percent effective in ventricular tachyarrhythmias. It appears to be of particular value in chronic atrial fibrillation/flutter because it may be able to maintain sinus rhythm after cardioversion. Side effects, although uncommon, may prevent the drug from becoming a standard of therapy. Drug interactions, particularly with warfarin and digoxin, as well as pulmonary fibrosis are of concern.

Role of intravenous verapamil in supraventricular tachyarrhythmias after open-heart surgery

Although the antiarrhythmic effects of verapamil (V) have been studied widely, its role in the treatment of atrial tachyarrhythmias after open-heart surgery (OHS) has not been defined. Accordingly, 22 patients were studied using a double-blind randomized crossover protocol 1 to 6 days after OHS, except for one patient, who was studied 90 days after OHS. Atrial fibrillation was seen in 18 and atrial flutter was observed in four patients. Two doses were used, 0.075 and 0.15 mg/kg (not exceeding 10 mg per dose), depending on the response. A positive response consisted of: conversion to sinus rhythm or heart rate less than 100 beats/minute (bpm). Eleven patients received V as the first drug; the remaining 11 received placebo first. Digoxin had been given to 20 patients (0.5 mg average dose) prior to inclusion in the study. Four patients converted to sinus rhythm within 30 minutes after V and one additional patient did so within 10 seconds of placebo administration. The post treatment heart rate combining both low and high dose response was 85 ± 18 compared to 128 ± 23 bpm for placebo (m ± SD, p < 0.01). The heart rate remained lower than control 30 minutes after V. Transient hypotension required intravenous fluid in one patient. Thus, V safely and rapidly controls heart rate but is not likely to result in immediate conversion to sinus rhythm in patients after OHS.

Atrial tachyarrhythmias in acute myocardial infarction

Causative factors, clinical consequences and treatment of atrial tachyarrhythmias were reviewed in 917 monitored patients with definite acute myocardial infarction. Significant atrial tachyarrhythmias were found in 104 (11 per cent) of them and included atrial fibrillation in 67, atrial flutter in 29 and paroxysmal atrial tachycardia in 33. These episodes were single in 79 patients and multiple in 25, and began within the first four days of acute myocardial infarction in 90 per cent of the patients. Fifty per cent of these atrial tachyarrhythmias were heralded by premature atrial contractions. The incidence of atrial tachyarrhythmia was not related to the location of the acute myocardial infarction or to the presence or degree of power failure; however, atrial tachyarrhythmias were significantly more frequent in patients with pericarditis. Atrial tachyarrhythmias were well tolerated in almost one fifth of the patients, caused marginal compromise in almost two thirds and led to severe clinical deterioration in one fifth. Paroxysmal atrial tachycardia rarely required specific treatment, atrial fibrillation was best managed with intravenous administration of digoxin except when associated with severe clinical compromise, and atrial flutter generally required cardioversion or rapid intravenous therapy and usually caused severe clinical deterioration. Over-all, atrial tachyarrhythmia was not associated with a significantly increased mortality, and in those who died, death was not related specifically to the atrial tachyarrhythmia but rather to the severity of the underlying acute myocardial infarction. However, persisting atrial tachyarrhythmias, particularly atrial flutter which tends to be refractory to both heart rate control and cardioversion, may contribute indirectly to morbidity and mortality.