benzofurans and Wolff-Parkinson-White-Syndrome

Topics: Administration, Oral; Amiodarone; Arrhythmias, Cardiac; Benzofurans; Cardiomyopathy, Hypertrophic; Heart; Heart Conduction System; Humans; Tachycardia, Paroxysmal; Thyroid Diseases; Thyroid Gland; Wolff-Parkinson-White Syndrome

Interest in amiodarone has increased because of its remarkable efficacy as an antiarrhythmic agent. The purpose of this report is to review what is known about the electrophysiologic actions, hemodynamic effects, pharmacokinetics, alterations of thyroid function, response to treatment of supraventricular and ventricular tachyarrhythmias and adverse effects of amiodarone. Understanding the actions of amiodarone and its metabolism will provide more intelligent use of the drug and minimize the development of side effects. The mechanism by which amiodarone suppresses cardiac arrhythmias is not known and may relate to prolongation of refractoriness in all cardiac tissues, suppression of automaticity in some fibers, minimal slowing of conduction in fast channel-dependent tissue, or to interactions with the autonomic nervous system, alterations in thyroid metabolism or other factors. Amiodarone exerts definite but fairly minor negative inotropic effects that may be offset by its vasodilator actions. Amiodarone has a reduced clearance rate, large volume of distribution, low bioavailability and a long half-life that may last 2 months in patients receiving short-term therapy. Therapeutic serum concentrations range between 1.0 and 3.5 micrograms/ml. The drug suppresses recurrences of cardiac tachyarrhythmias in a high percent of patients, in the range of 80% or more for most supraventricular tachycardias and in about 66% of patients with ventricular tachyarrhythmias, sometimes requiring addition of a second antiarrhythmic agent. Side effects, particularly when high doses are used, may limit amiodarone's usefulness and include skin, corneal, thyroid, pulmonary, neurologic, gastrointestinal and hepatic dysfunction. Aggravation of cardiac arrhythmias occurs but serious arrhythmias are caused in less than 5% of patients. Amiodarone affects the metabolism of many other drugs and care must be used to reduce doses of agents combined with amiodarone.

Topics: Administration, Oral; Amiodarone; Animals; Arrhythmias, Cardiac; Atrioventricular Node; Benzofurans; Biological Availability; Drug Interactions; Electrophysiology; Eye Diseases; Half-Life; Heart Conduction System; Humans; Injections, Intravenous; Kinetics; Lung Diseases; Metabolic Clearance Rate; Photosensitivity Disorders; Purkinje Fibers; Tachycardia; Thyroid Diseases; Wolff-Parkinson-White Syndrome

Topics: Adolescent; Adrenergic beta-Antagonists; Adult; Aged; Ajmaline; Amiodarone; Anilides; Aprindine; Atrial Fibrillation; Benzofurans; Digitalis Glycosides; Disopyramide; Encainide; Female; Humans; Lidocaine; Male; Middle Aged; Procainamide; Quinidine; Tachycardia; Verapamil; Wolff-Parkinson-White Syndrome

Topics: Acute Disease; Administration, Oral; Amiodarone; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Atrial Fibrillation; Benzofurans; Cardiovascular System; Dose-Response Relationship, Drug; Electrophysiology; Eye Manifestations; Heart Block; Humans; Injections, Intravenous; Muscle, Smooth, Vascular; Myocardial Infarction; Skin Manifestations; Tachycardia; Thyroid Gland; Wolff-Parkinson-White Syndrome

Topics: Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Amiodarone; Angina Pectoris; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Benzofurans; Clinical Trials as Topic; Drug Evaluation; Humans; Hypothyroidism; Myocardial Contraction; Oxygen Consumption; Parasympatholytics; Structure-Activity Relationship; Tachycardia, Paroxysmal; Thyroid Gland; Vascular Resistance; Vasodilator Agents; Wolff-Parkinson-White Syndrome

Topics: Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Amiodarone; Angina Pectoris; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Benzofurans; Clinical Trials as Topic; Drug Evaluation; Humans; Hypothyroidism; Myocardial Contraction; Oxygen Consumption; Parasympatholytics; Structure-Activity Relationship; Tachycardia, Paroxysmal; Thyroid Gland; Vascular Resistance; Vasodilator Agents; Wolff-Parkinson-White Syndrome

Six patients with Wolff-Parkinson-White (WPW) syndrome were given long-term treatment with amiodarone. Symptomatic relief was obtained in all. Tolerance to the drug was good. Reversible corneal changes appeared after some weeks' treatment in five patients. No thyroid side-effects were noticed. Prior to treatment, dual atrioventricular (AV) conduction was demonstrated on His bundle electrograms in all six patients. Recordings were made at varied heart rates, using atrial and ventricular pacing. Reciprocating tachycardia was readily provoked by properly timed extra stimuli in all patients. When amiodarone treatment had become clinically effective, a second comparative study was made in four patients after 26--85 days' treatment. Amiodarone reduced heart rate and second degree AV block appeared at a lower atrial pacing rate. It increased the refractory periods of right atrium, AV node, and the accessory pathway in proportion to the duration of treatment. Induction of tachycardia was effectively prevented by the drug. It appears that amiodarone in chronic treatment has a predictable and unique depressant action on cardiac conduction, supporting the opinion that this compound, despite side-effects, has an important role to play in the treatment of refractory arrhythmias in patients with the WPW syndrome.

Topics: Adult; Aged; Amiodarone; Benzofurans; Bundle of His; Cardiac Pacing, Artificial; Clinical Trials as Topic; Drug Evaluation; Electrocardiography; Female; Heart Conduction System; Heart Rate; Humans; Male; Middle Aged; Sinoatrial Node; Time Factors; Wolff-Parkinson-White Syndrome

Eight patients with WPW syndrome were catheterised and, during the course of this investigation, the electrophysiological effects of amiodarone were assessed. By registering the potentials of the bundle of His and by using the stimulus-test technique, we were able to measure the refractory periods of the atrium and of the normal and accessory conducting pathways both before and during the first 40 minutes after an intra-atrial injection of 5 mg/kg of amiodarone chlorhydrate. The action of the conduction time was also studied. In the five cases in which we were able to measure it, the effective refractory period of the abnormal pathway increased, which led in two instances to the temporary suppression of all pre-excitation. At the same time, it was repeatedly found that the refractory periods of the A-V node were increased: the effective refractory period in 3/3 cases, and the functional refractory period in 2/2 cases. The effective refractory period of the right atrium was increased in 5 cases, and did not change in the others. The intranodal conduction time (A-H- interval) was always increased after amiodarone. Finally, in three patients runs of reciprocal tachycardia could be initiated by premature atrial stimulation. In one case, this was no longer possible after amiodarone. In the other two cases, although the attacks could still be brought on, they were slower because of the lengthening of the A-H interval. These findings explain why amiodarone is effective in controlling the tachycardia of WPW syndrome.

Topics: Action Potentials; Adult; Amiodarone; Anti-Arrhythmia Agents; Benzofurans; Bundle of His; Clinical Trials as Topic; Female; Heart Conduction System; Humans; Male; Middle Aged; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adult; Amiodarone; Atrial Fibrillation; Benzofurans; Electrocardiography; Female; Heart; Humans; Male; Middle Aged; Refractory Period, Electrophysiological; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adolescent; Adult; Aged; Amiodarone; Benzofurans; Cardiac Pacing, Artificial; Electrocardiography; Electrophysiology; Female; Heart Atria; Humans; Male; Middle Aged; Time Factors; Wolff-Parkinson-White Syndrome

This study was performed to ascertain whether intravenous amiodarone would revert supraventricular tachycardias to sinus rhythm, and if so, whether this effect depended upon the underlying mechanism of the arrhythmia. Fourteen patients were studied. Seven had Wolff-Parkinson-White (WPW) syndrome, 1 had dual atrioventricular nodal pathways and 1 an ectopic atrial tachycardia. Five patients had atrial fibrillation without accessory pathways. An atrial electrode was inserted to initiate tachycardias and record the electrogram. If tachycardias were stable for more than 5 min, amiodarone (5 mg/kg) diluted with dextrose saline was infused intravenously over 5 min. Two electrocardiographic leads and the right atrial electrogram were monitored. In 7 patients with atrial fibrillation (2 with accessory pathways), 6 did not revert to sinus rhythm, 1 reverted only after 1 hr. In 5 cases without accessory pathways the ventricular rate fell 5-10 min after commencing amiodarone. Four of the 5 patients with WPW syndrome and re-entrant tachycardias returned to sinus rhythm within 6 min of commencing the infusion (atrioventricular and ventriculoatrial times increased by 0-38% and 0-14% respectively). (Tachycardias terminated in the anterograde limb.) Three patients underwent intermittent right atrial stimulation for 1 hr. No tachycardias could be initiated for 30 min post amiodarone. The ectopic atrial tachycardia and that due to dual atrioventricular nodal pathways terminated within 7 and 2 min, respectively, of commencing intravenous amiodarone. Thus the use of intravenous amiodarone would be appropriate in the acute management of sustained supraventricular tachycardias.

Topics: Adolescent; Adult; Aged; Amiodarone; Atrial Fibrillation; Atrioventricular Node; Benzofurans; Cardiac Pacing, Artificial; Electrocardiography; Female; Heart Ventricles; Humans; Injections, Intravenous; Male; Middle Aged; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adult; Amiodarone; Atrial Fibrillation; Benzofurans; Electrocardiography; Female; Fetal Blood; Humans; Pregnancy; Pregnancy Trimester, Second; Wolff-Parkinson-White Syndrome

In a 20-year-old patient with Marfan's syndrome and Wolff-Parkinson-White syndrome, effective amiodarone treatment had to be stopped due to serious hyperthyroidism. Diagnosis and therapy of amiodarone-induced dysthyroidism is discussed.

Topics: Adult; Amiodarone; Benzofurans; Female; Humans; Hyperthyroidism; Marfan Syndrome; Thyroid Function Tests; Wolff-Parkinson-White Syndrome

The refractory periods during cardiac pacing were studied in 13 patients with the Wolff-Parkinson-White syndrome. The right atrial and right ventricular refractory periods and refractory period of the accessory pathway (anterogradely and retrogradely) were studied at 2 pacing cycle lengths before and after therapy with oral amiodarone (8,400 to 11,200 mg given in 4 to 6 weeks). The right atrial and right ventricular effective refractory period shortened significantly when the pacing rate was increased during the control study, and also after oral amiodarone administration. The anterograde and retrograde effective refractory period of the accessory pathway also shortened significantly at control study, but not during treatment with oral amiodarone. This indicated that amiodarone blunted the rate-dependent shortening in the refractory period of the accessory pathway. The rate-dependent increase in refractoriness of the accessory pathway could not be predicted or determined in all patients. In 5 patients a rate-dependent increase in the effective refractory period of the accessory pathway was observed in the anterograde direction and in 3 patients in the retrograde direction while they were receiving oral amiodarone therapy. When these data were correlated with the mode of induction and termination of tachycardia, however, a possible effect was found in only 1 patient. Further investigation of new antiarrhythmic drugs should include the development of components resulting in a reliable and predictable increase in refractoriness when the heart rate increases. This would result in prompt termination of reentrant tachycardia by creating block for the circulating impulse.

Topics: Administration, Oral; Amiodarone; Benzofurans; Cardiac Pacing, Artificial; Electrophysiology; Heart Atria; Heart Conduction System; Heart Ventricles; Humans; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Amiodarone; Benzofurans; Biopsy; Child; Female; Hepatic Encephalopathy; Humans; Liver; Reye Syndrome; Wolff-Parkinson-White Syndrome

Sudden death in Wolff-Parkinson-White syndrome (WPW) is related to a very fast ventricular response to spontaneous atrial fibrillation (AF) conducted via accessory pathway (AP). The effect of oral amiodarone was studied in 12 patients with WPW syndrome and life-threatening rapid ventricular response via an AP during spontaneous AF. The effective refractory period of the AP in the anterograde direction was 280 ms or less during control study in all patients. After amiodarone therapy, the effective refractory period remained 280 ms or less in 7 of the 12 patients. During incremental atrial pacing, the longest atrial pacing cycle length that produced block over an AP ranged from 200 to 310 ms (mean 261 +/- 42) during the control period and 240 to 980 ms (mean 377 +/- 198) after amiodarone therapy. During AF the shortest ventricular response via the AP could be measured in 10 of 12 of the patients both before and after amiodarone treatment and ranged from 200 to 290 ms (234 +/- 30) and 250 to 500 (mean 302 +/- 75), respectively (p less than 0.01). The average RR interval during AF before and after the drug ranged from 200 to 390 ms (mean 280 +/- 55) and 280 to 650 ms (mean 396 +/- 116), respectively (p less than 0.01). Thus, the safety of amiodarone in the WPW syndrome should be established by electrophysiologic studies and induction of AF, because amiodarone is not protective in all patients with WPW.

Topics: Adolescent; Adult; Amiodarone; Atrial Fibrillation; Benzofurans; Cardiac Pacing, Artificial; Electrocardiography; Female; Heart Conduction System; Humans; Male; Middle Aged; Prospective Studies; Tachycardia; Wolff-Parkinson-White Syndrome

In 12 patients (nine with Wolff-Parkinson-White syndrome and three with ventricular tachycardia) the electrophysiologic effects of intravenous (5 mg/kg body weight in 1 min) and oral (total dose 9800 to 11,200 mg) amiodarone were studied with programmed stimulation of the heart. Intravenous and oral amiodarone had a similar (p less than .05) effect of lengthening on the effective refractory period of the atrioventricular node. Only intravenous amiodarone prolonged (p less than .05) the AH interval. Oral amiodarone was more effective than intravenous amiodarone in lengthening the anterograde effective refractory period of the accessory atrioventricular pathway. Only oral amiodarone prolonged the effective refractory period of atrium and ventricle and the HV interval, all significantly (p less than .05). Intravenous amiodarone slowed (p less than .05) the rate of circus-movement tachycardia in patients with Wolff-Parkinson-White syndrome, and further slowing was observed after oral amiodarone. Termination of tachycardia by intravenous amiodarone predicted prevention of reinitiation of tachycardia during oral amiodarone. These data indicate that intravenous and oral amiodarone do not have the same electrophysiologic effects. It is not clear whether cumulative effects, active metabolites, or both are responsible for these differences.

Topics: Administration, Oral; Adolescent; Adult; Amiodarone; Benzofurans; Cardiac Pacing, Artificial; Child; Electrocardiography; Electrophysiology; Female; Heart Conduction System; Heart Rate; Humans; Injections, Intravenous; Male; Middle Aged; Tachycardia; Wolff-Parkinson-White Syndrome

Ten patients with refractory recurrent supraventricular tachycardia were found by electrophysiologic study to have bypass tracts and orthodromic atrioventricular reentrant tachycardia. All had failed to respond to conventional antiarrhythmic therapy and were therefore treated with oral amiodarone (1,600 to 2,000 mg/day for 2 weeks, then 800 to 1,200 mg/day for another 2 weeks with subsequent 200 to 600 mg/day maintenance doses). During or after the fourth week of therapy, electrophysiologic study was repeated. In 9 of 10 patients, supraventricular tachycardia could not be reinduced by programmed stimulation. In the remaining patient, nonsustained supraventricular tachycardia (greater than 10 beats, lasting less than 30 seconds) with a slower basic cycle length than that during the control period was provoked. Significant increases in the effective refractory period of the accessory pathway in both the anterograde (+26%, p less than 0.05) and retrograde (+40%, p less than 0.02) directions were noted, the magnitude of change being independent of the control effective refractory period. There were also significant increases in the effective refractory period of the right atrium (+24%, p less than 0.01) and the right ventricle (+15%, p less than 0.01) during long-term therapy with amiodarone. Over a mean follow-up period of 20 months, symptomatic control of the arrhythmia occurred in all patients; in only one patient treatment with amiodarone could not be continued because of side effects. These data establish the electrophysiologic basis for the effectiveness of amiodarone in the prophylactic control of refractory paroxysmal supraventricular tachycardia complicating the bypass tract syndromes.

Topics: Adult; Aged; Amiodarone; Benzofurans; Digoxin; Electrocardiography; Heart Conduction System; Humans; Male; Middle Aged; Propranolol; Tachycardia; Wolff-Parkinson-White Syndrome

Amiodarone was used in 40 patients with life-threatening or refractory tachyarrhythmias. Eighteen patients had recurrent ventricular tachycardia of whom 13 had suffered a cardiac arrest. Control has been excellent or good in 17 of these 18 patients during an average follow-up period of 10 months. A further 22 patients had supraventricular arrhythmias, including three with Wolff-Parkinson-White syndrome and paroxysmal atrial fibrillation. In 20 of these control has been excellent or good. The mean daily maintenance dose of amiodarone was 300 mg for patients with ventricular tachyarrhythmias and 200 mg for those with supraventricular tachyarrhythmias. Side-effects were common and included corneal microdeposits, skin rash and discolouration, alteration in thyroid function, and symptomatic bradycardia. Serious adverse effects were uncommon however and necessitated discontinuation of the drug in only two patients. Amiodarone did not appear to precipitate or exacerbate cardiac failure in any patient although many had severe left ventricular dysfunction. We conclude that amiodarone is effective in the therapy of life-threatening or refractory cardiac arrhythmias.

Topics: Adolescent; Adult; Aged; Amiodarone; Arrhythmias, Cardiac; Benzofurans; Female; Humans; Kinetics; Male; Middle Aged; Tachycardia; Ventricular Fibrillation; Wolff-Parkinson-White Syndrome

In Wolff-Parkinson-White (WPW) syndrome, the two most commonly occurring arrhythmias are circus movement tachycardia (CMT) and atrial fibrillation (AF). In 70% of patients with clinically documented CMT in whom the arrhythmia could be initiated by programmed electrical stimulation of the heart, the same CMT could still be initiated after long-term oral amiodarone administration. Spontaneous clinical recurrence of the arrhythmia was, however, observed in only 10% of patients. This finding suggests that the beneficial effect of amiodarone on CMT is primarily based on the prevention of the CMT-initiating premature beat. This may also apply to atrioventricular nodal reentrant tachycardia, in which amiodarone is also extremely effective in preventing relapses. The role of amiodarone in other forms of reentrant, or ectopic, supraventricular tachycardias is less well defined. During AF in WPW syndrome, the ventricular rate is related to the duration of the anterograde refractory period of the accessory pathway. Amiodarone prolongs this value, resulting in the reduction of ventricular rate during AF. Unfortunately, in the presence of a short anterograde refractory period of the accessory pathway, amiodarone results in only a small amount of lengthening of this value. In these patients the beneficial effect of amiodarone may primarily be related to the prevention of episodes of AF. We also found that the effect of oral amiodarone on the duration of the anterograde refractory period of the accessory pathway can (1) be abolished by sympathetic stimulation with isoproterenol and (2) be predicted from the effect of ajmaline or procainamide given intravenously. These observations clearly have practical clinical implications.

Topics: Ajmaline; Amiodarone; Atrial Fibrillation; Benzofurans; Electrophysiology; Heart; Humans; Isoproterenol; Procainamide; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome

Arrhythmias may be controlled in most patients with recurrent supraventricular tachycardia or atrial fibrillation with small to moderate maintenance doses of amiodarone (100 to 400 mg/day). Moderate doses (400 mg/day) are also highly effective in suppressing "warning" ventricular arrhythmias in patients with chronic ischemic heart disease, particularly if the goal of treatment is to eliminate ventricular couplets, runs of ventricular tachycardia (VT), and the "R on T" phenomenon. Treatment and prevention of sustained recurrent VT and the malignant arrhythmias of chagasic myocarditis require, however, doses of about 800 mg/day, which may be higher than those needed for ischemic heart disease complicated by VT and ventricular fibrillation. Clinical studies suggest an elimination half-life for amiodarone of about 30 days (range 15 to 100 days). Thus there is a pretherapeutic latency period that varies according to the type of arrhythmia and the doses employed. The maximal effects (as well as the most significant adverse effects) are not attained before 90 to 150 days of treatment, and the antiarrhythmic protection may persist for varying intervals, up to 150 days or more, after the drug has been discontinued. Side effects are not negligible but are generally dose dependent. Despite these side effects, many patients have been treated by us with amiodarone for as long as 5 to 8 years--and for up to 10 years in some cases. Amiodarone appears to be one of the most promising drugs for the possible prevention of ventricular fibrillation and sudden death.

Topics: Amiodarone; Arrhythmias, Cardiac; Atrial Fibrillation; Benzofurans; Chagas Cardiomyopathy; Dose-Response Relationship, Drug; Drug Interactions; Half-Life; Heart Ventricles; Humans; Kinetics; Wolff-Parkinson-White Syndrome

Oral amiodarone was administered to ten children aged 3 months to 15 years who had recurrent SVT associated with the Wolff-Parkinson-White syndrome. In nine patients, amiodarone was used following failure of oral digoxin, quinidine, propranolol, and verapamil. Each patient received an oral loading dose of 10 to 15 mg/kg followed by 5 mg/kg daily. All children became asymptomatic of tachyarrhythmias within five days of therapy and remained asymptomatic for 5 to 36 months. In one patient, amiodarone therapy was discontinued because of generalized urticaria after a positive initial response. After high-dose oral verapamil failed to eliminate recurrent bouts of SVT, the patient was again given amiodarone and he had a complete recovery. All ten children had normal results on thyroid function tests, and no other adverse effects were detected. Amiodarone has been shown to be highly effective and well tolerated in this series of children. Therefore, we recommend its use for the control and prevention of sustained arrhythmias in pediatric patients with Wolff-Parkinson-White syndrome when the traditional antiarrhythmic drugs fail.

Topics: Administration, Oral; Adolescent; Amiodarone; Benzofurans; Child; Child, Preschool; Electrocardiography; Female; Humans; Infant; Male; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adolescent; Amiodarone; Benzofurans; Child; Child, Preschool; Humans; Infant; Tachycardia; Wolff-Parkinson-White Syndrome

A patient with types A and B of Wolff-Parkinson-White syndrome developed subacute pneumonitis during long-term treatment with amiodarone. The pneumopathy occurred only when the maintenance dose was increased to 800 mg/day. Lung specimens obtained by transbronchial biopsy showed chronic pneumonitis with C3 deposition by immunofluorescence. Pulmonary signs spontaneously disappeared two months after the drug was discontinued.

Topics: Amiodarone; Benzofurans; Female; Humans; Lung; Middle Aged; Pneumonia; Wolff-Parkinson-White Syndrome

In patients with the Wolff-Parkinson-White syndrome, intravenous ajmaline (50 mg administered over 3 minutes) or procainamide (10 mg/kg body weight administered over 10 minutes) is helpful in defining the duration of the anterograde effective refractory period of the accessory pathway. In this study the value of the ajmaline-procainamide test to predict the effects on the anterograde effective refractory period of the accessory pathway of long-term oral amiodarone were assessed. Thirty-six patients with the Wolff-Parkinson-White syndrome were studied. Twenty-four (Group A) had a negative result of the ajmaline-procainamide test and a mean duration of the anterograde effective refractory period of the accessory pathway of 237 +/- 24 ms. Twelve (Group B) had a positive result in the ajmaline-procainamide test (disappearance of preexcitation during sinus rhythm after administration of ajmaline and procainamide) and a duration of the anterograde effective refractory period of the accessory pathway of 284 +/- 25 ms (p less than 0.05 versus values in Group A). Amiodarone prolonged the anterograde effective refractory period of the accessory pathway by 53 +/- 35 ms in patients in Group A to 290 +/- 37 ms (p less than 0.001) and by 100 +/- 85 ms in patients in Group B to 384 +/- 94 ms (p less than 0.001). The difference in mean increase between both groups was not significant. In most patients (83%) in Group A amiodarone prolonged the anterograde effective refractory period of the accessory pathway to 260 to 330 ms. However, in most patients (83%) in Group B, amiodarone prolonged the anterograde effective refractory period of the accessory pathway to greater than or equal to 330 ms (p less than 0.01). Thus, an ajmaline-procainamide test is of value in predicting the results of oral amiodarone on the anterograde effective refractory period of the accessory pathway.

Topics: Adolescent; Adult; Ajmaline; Amiodarone; Benzofurans; Electrophysiology; Female; Heart Conduction System; Humans; Male; Middle Aged; Procainamide; Time Factors; Wolff-Parkinson-White Syndrome

Amiodarone has proved to be a valuable drug in atrial fibrillation associated with the Wolff-Parkinson-White syndrome. When it was administered to a patient with this syndrome in atrial fibrillation, who had previously suffered an inferior myocardial infarction, the ventricular rate accelerated from 170 to 230 beats/minute.This unusual case emphasises the need for full electrophysiological assessment of patients with the Wolff-Parkinson-White syndrome for whom amiodarone treatment is being considered.

Topics: Aged; Amiodarone; Atrial Fibrillation; Benzofurans; Electrocardiography; Humans; Male; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adrenergic beta-Antagonists; Ajmaline; Amiodarone; Benzofurans; Drug Therapy, Combination; Humans; Quinidine; Tachycardia; Verapamil; Wolff-Parkinson-White Syndrome

Amiodarone was used in 30 patients with tachyarrhythmias refractory to treatment with several antiarrhythmic agents. In 18 patients with supraventricular arrhythmias (recurrent atrial tachycardia in seven; atrial fibrillation, recurrent in four and persistent in five; Wolff-Parkinson-White syndrome in two), complete control was obtained in eight and marked improvement in eight patients. Conversion of persistent atrial fibrillation to sinus rhythm was documented in three patients. Congestive heart failure improved markedly in three patients who had persistent atrial fibrillation during amiodarone therapy. In 12 patients with tachycardia of ventricular origin effective control was obtained in nine. The incidence of side effects was low. Amiodarone is effective in maintaining sinus rhythm in many patients with both supraventricular and ventricular tachyarrhythmias when standard antiarrhythmic agents have failed.

Topics: Adult; Aged; Amiodarone; Arrhythmias, Cardiac; Atrial Fibrillation; Benzofurans; Female; Heart Atria; Heart Ventricles; Humans; Male; Middle Aged; Recurrence; Tachycardia; Wolff-Parkinson-White Syndrome

Amiodarone was utilized in 70 patients with symptomatic, sustained refractory tachyarrhythmias. Of these, 29 had atrial arrhythmia (20 recurrent atrial fibrillation and nine sustained supraventricular tachycardia). Control was achieved in eight with supraventricular tachycardia and in 16 with atrial fibrillation. Recurrence has been prevented in these 24 patients (83%) during an average follow-up of 13.4 months. An additional 41 patients had recurrent ventricular tachycardia. In 19 with symptoms consisting of dizziness of lightheadedness without syncope or clinically apparent hemodynamic compromise, treatment was limited to amiodarone. Of these, 14 responded (74%) and have been free of arrhythmia during an average follow-up of 13 months. In 22 who had experienced either syncope or life-threatening hemodynamic impairment, amiodarone was added to those agents which had only partially suppressed advanced grades of ventricular premature beats. Fourteen of these patients (64%) have remained free pf recurrent ventricular arrhythmia during an average follow-up of 12 months. After drug loading, maintenance therapy consisted of a daily dose ranging from 200 to 600 mg. Only mild side effects have been encountered in the 17 patients (23%) with any untoward responses. This experience confirms that oral amiodarone is an effective and safely applied agent against recurrent refractory atrial tachyarrhythmia and sustained intractable ventricular tachycardia with moderate symptoms. While also efficacious in refractory sustained life-threatening ventricular tachyarrhythmia, usage of the agent is often difficult in this condition owing in part to insufficient information concerning amiodarone pharmacokinetics.

Topics: Adolescent; Adult; Aged; Amiodarone; Arrhythmias, Cardiac; Benzofurans; Female; Humans; Male; Middle Aged; Tachycardia; Time Factors; Wolff-Parkinson-White Syndrome

Oral amiodarone has been used to treat 21 patients with various supraventricular arrhythmias; 13 had Wolff-Parkinson-White syndrome, which was complicated by atrial fibrillation and re-entry atrioventricular tachycardia in four, and re-entry tachycardia alone in the other nine. The remaining eight patients had paroxysmal atrial fibrillation or flutter without pre-excitation. All were refractory to conventional treatment and had undergone intracardiac electrophysiological study. Fifteen have been controlled with amiodarone, this treatment proving most effective in atrial fibrillation or flutter with or without pre-excitation. Amiodarone was successful in only four of the nine patients with re-entry atrioventricular tachycardia. In two patients who responded well the drug had to be discontinued because of side effects.

Topics: Adult; Aged; Amiodarone; Arrhythmias, Cardiac; Atrial Fibrillation; Atrial Flutter; Benzofurans; Electrocardiography; Humans; Middle Aged; Wolff-Parkinson-White Syndrome

Oral amiodarone, an iodine-containing antiarrhythmic agent, was administered to 72 patients with recurrent paroxysmal tachycardias. Thirty-nine patients had tachycardias associated with the Wolff-Parkinson-White syndrome, 15 patients had paroxysmal atrial fibrillation unassociated with the Wolff-Parkinson-White syndrome, and 18 patients had ventricular tachycardia. In all patients, the frequency of symptomatic attacks had not been reduced by at least three other antiarrhythmic agents alone or in combination. The response to amiodarone treatment was graded according to the patients' subjective response (total suppression, partial suppression, and no effect). Overall, 57 per cent of patients had total abolition of attacks and another 22 per cent had a partial suppression of attacks. Side effects, the most common of which were photosensitivity and gastrointestinal upsets, occurred in 44 per cent and were sufficiently severe to warrant withdrawal of treatment in 15 per cent. These results confirm that amiodarone is of considerable value in the treatment of recurrent paroxysmal arrhythmias resistant to other drugs.

Topics: Adolescent; Adult; Aged; Amiodarone; Atrial Fibrillation; Benzofurans; Child; Drug Administration Schedule; Humans; Middle Aged; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome

Topics: Aged; Amiodarone; Benzofurans; Bradycardia; Female; Heart Rate; Humans; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome

Topics: Adolescent; Adult; Aged; Amiodarone; Atrial Fibrillation; Atrioventricular Node; Benzofurans; Cardiac Pacing, Artificial; Electric Stimulation Therapy; Electrocardiography; Female; Heart Conduction System; Heart Rate; Humans; Male; Middle Aged; Refractory Period, Electrophysiological; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome

The effects of amiodarone (2.5 mg/Kg i.v.) and of verapamil (0.1 mg/Kg i.v.) on refractory periods and on conduction of structures interested in the reciprocating circuit, as well as on the possible echo zones, were comparatively evaluated through electrophysiological test in 8 patients, four of which with W.P.W. from Kent bundle, and four with double A-V pass with reciprocating supraventricular tachicardia (RST) documented crises. None of the two drugs seems to have the theorical requirements of balanced effect to be chosen for the antiarrhythmic prophylaxis in patients with ventricular pre-excitement. In patients with double A-V pass, while both drugs have a sufficiently balanced and regular action on refractory periods and on conduction the irregularity of their effects on echo zones appears to restrict their validity in chronical therapy. According to the Authors, the only useful criteria for the choice of an antiarrhythmic drug for the prophilaxis of R.S.T. to be derived through extrapolation from these electrophysiological tests are: 1) the functional suppression of a circuit structure; 2) the evaluation of effects on echo zones; 3) the possibility or not the evoking R.S.T.

Topics: Adult; Aged; Amiodarone; Benzofurans; Drug Evaluation; Female; Humans; Male; Middle Aged; Tachycardia, Paroxysmal; Verapamil; Wolff-Parkinson-White Syndrome

Topics: Aged; Amiodarone; Atrial Fibrillation; Benzofurans; Electrocardiography; Humans; Male; Wolff-Parkinson-White Syndrome

The effect of amiodarone in the Wolff-Parkinson-White syndrome was studied with programmed electrical stimulation of the heart in 15 patients. All 15 patients had circus movement tachycardias; 7 also had atrial fibrillation. Programmed electrical stimulation was performed before and after 14 days of oral administration of amiodarone. The effective refractory period of the accessory pathway lengthened in an atrioventricular direction in all patients and in a ventriculoatrial direction in eight patients. The effective refractory period of the atrium and ventricle lengthened in 14 and 12 patients, respectively. After administration of amiodarone, circus movement tachycardia could no longer be initiated in five patients. The zone of tachycardia narrowed in four patients, did not change in two and increased in seven. The effect of amiodarone on initiation of circus movement tachycardia could be related to differences in effect of the drug and in the mechanism of tachycardia in individual patients. In all patients in whom tachycardias could still be initiated after treatment with amiodarone the heart rate during tachycardia was slower than before treatment. This slowing was caused by a decrease in conduction velocity of the circulatory wave in different parts of the tachycardia circuit. The effect of amiodarone in prolonging the refractory period of the accessory pathway makes this drug especially useful in patients with the Wolff-Parkinson-White syndrome and atrial fibrillation.

Topics: Adolescent; Adult; Amiodarone; Atrial Fibrillation; Atrioventricular Node; Benzofurans; Electrocardiography; Female; Heart Atria; Heart Ventricles; Humans; Male; Middle Aged; Neural Conduction; Pacemaker, Artificial; Refractory Period, Electrophysiological; Tachycardia; Wolff-Parkinson-White Syndrome

Topics: Adolescent; Adult; Aged; Anti-Arrhythmia Agents; Atrial Fibrillation; Atrial Flutter; Benzofurans; Cornea; Female; Heart Conduction System; Humans; Male; Middle Aged; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome