Electrophysiological assessment of amiodarone in treatment of resistant supraventricular arrhythmias.

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.     

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part II: ventricular arrhythmias, channelopathies and implantable defibrillators.

This consensus paper on behalf of the Study Group on Sports Cardiology of the European Society of Cardiology follows a previous one on guidelines for sports participation in competitive and recreational athletes with supraventricular arrhythmias and pacemakers. The question of imminent life-threatening arrhythmias is especially relevant when some form of ventricular rhythm disorder is documented, or when the patient is diagnosed to have inherited a pro-arrhythmogenic disorder. Frequent ventricular premature beats or nonsustained ventricular tachycardia may be a hallmark of underlying pathology and increased risk. Their finding should prompt a thorough cardiac evaluation, including both imaging modalities and electrophysiological techniques. This should allow distinguishing idiopathic rhythm disorders from underlying disease that carries a more ominous prognosis. Recommendations on sports participation in inherited arrhythmogenic conditions and asymptomatic gene carriers are also discussed: congenital and acquired long QT syndrome, short QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, arrhythmogenic right ventricular cardiomyopathy and other familial electrical disease of unknown origin. If an implantable cardioverter defibrillator is indicated, it is no substitute for the guidelines relating to the underlying pathology. Moreover, some particular recommendations for patients/athletes with an implantable cardioverter defibrillator are to be observed.     

The relationship of arrhythmias and conduction disturbances to other manifestations of cardiopulmonary disease in progressive systemic sclerosis (PSS)

Disorders of rhythm and conduction are characteristic of the cardiac involvement in progressive systemic sclerosis (PSS), but their over-all frequency in PSS is not well established. Therefore, 46 ambulatory patients with PSS underwent several tests of cardiopulmonary function, including a 24-hour continuous electrocardiogram (Holter monitor). Conduction disturbances (sinus node dysfunction, first-degree heart block, pre-excitation), supraventricular arrhythmias (supraventricular tachycardia, atrial fibrillation, premature contractions of atrial or junctional origin) and ventricular arrhythmias (ventricular tachycardia, multifocal premature contractions) were observed on Holter monitoring in 26 subjects. Although these arrhythmias and conduction disorders were predictably observed in patients who complained of palpitations or syncope, or who had an electrocardiogram which showed first-degree heart block, ventricular bigeminy, left anterior superior hemiblock, prolonged p wave, right or left axis deviation, right or left ventricular hypertropy, pathologic Q waves or low voltage, they were often found in patients who lacked other clinical evidences of heart disease. Arrhythmias and conduction disturbances were not significantly more frequent among patients with cardiomegaly or interstitial change on chest roentgenogram nor were they related to the presence or severity of abnormal lung function. This study suggests that Holter monitoring may be a valuable adjunct in evaluating heart disease in PSS.     

Mitral valve prolapse syndrome and arrhythmias

In patients with mitral valve prolapse syndrome various disturbances of cardiac rhythm can be observed such as atrial arrhythmias, ventricular tachycardias and conduction disturbances. Of timely interest are the questions of which etiology is at the basis of the arrhythmias, what is their relevance with respect to sudden cardiac death, what are the indications for treatment and which therapeutic results can be anticipated. Cardiac arrhythmias represent the most frequent complication of mitral valve prolapse. Holter ECG monitoring has assumed the central role in detection of all types of arrhythmias. As compared with normal persons, in patients with mitral valve prolapse, both ventricular and supraventricular arrhythmias can be found more frequently. Atrial arrhythmias: Supraventricular arrhythmias can be found less frequently than ventricular arrhythmias (Table 1). Premature atrial contractions can be observed in 35% of those with mitral valve prolapse but also in a similar number of normal individuals such that their presence is not of clinical relevance. There is only a tendency to more frequently incurred supraventricular couplets in mitral valve prolapse. Supraventricular tachycardias can be observed in 10.5 to 32% of which sinus tachycardia (heart rate greater than 120 beats per minute), paroxysmal atrial tachycardia and intermittent atrial fibrillation at about 5 to 6% each are not more common than in control subjects. Atrial fibrillation was seen more frequently in mitral valve prolapse with mitral regurgitation or, conversely, in mitral regurgitation due to mitral valve prolapse more frequently than in mitral regurgitation due to other causes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peri-operative supraventricular arrhythmias in coronary bypass surgery

One hundred consecutive admissions for coronary bypass surgery were studied to establish the incidence of peri-operative supraventricular arrhythmias, to monitor their evolution, and to identify their possible aetiological factors. No important arrhythmias were detected before the operation. Post-operatively, 24 patients (24%) developed supraventricular arrhythmias. Nineteen of them had atrial fibrillation or flutter (19%), 2 had supraventricular tachycardia (2%), and 3 had inappropriate sinus bradycardia (less than 45 min) (3%). Almost two-thirds of the arrhythmias occurred within the critical early post-operative period (63%). Haemodynamic compromise ushered the onset of arrhythmias in more than one-third of the patients in whom antiarrhythmic measures ensured prompt improvement (37.5%). Three-quarters of those with atrial fibrillation or flutter were back in sinus rhythm at the time of discharge from hospital (74%). The incidence of supraventricular arrhythmia was significantly higher in patients with demonstrable myocardial ischaemia prior to surgery, in patients who underwent adjunctive coronary endarterectomy, or in those in whom topical cardiac cooling was applied (50%, 45%, and 58%, respectively). Supraventricular arrhythmias are frequently encountered during the critical early post-operative period when serious but reversible haemodynamic compromise might be precipitated. Although the nature of the underlying myocardial insult remains obscure, supraventricular arrhythmia may be related more to defective myocardial preservation than to any specific underlying myocardial lesion.     

Cardiac arrhythmias in pregnancy: clinical and therapeutic considerations

Pregnancy can precipitate cardiac arrhythmias not previously present in seemingly well individuals. Risk of arrhythmias is relatively higher during labor and delivery. Potential factors that can promote arrhythmias in pregnancy and during labor and delivery include the direct cardiac electrophysiological effects of hormones, changes in autonomic tone, hemodynamic perturbations, hypokalemia of pregnancy, and underlying heart disease. Paroxysmal supraventricular and ventricular tachycardia may cause hemodynamic compromise with consequences to the fetus. Management of arrhythmias in pregnant women is similar to that in non-pregnant but a special consideration must be given to avoid adverse fetal effects. No drug therapy is usually needed for the management of supraventricular or ventricular premature beats, but potential stimulants, such as smoking, caffeine, and alcohol should be eliminated. In paroxysmal supraventricular tachycardia, vagal stimulation maneuvers should be tried first. Adenosine or a cardioselective beta-blocker could be used if vagal maneuvers are ineffective. Alternatively, verapamil or diltiazem may be given. In pregnant women with atrial fibrillation, the goal of treatment is conversion to sinus rhythm or to control ventricular rate by a cardioselective beta-adrenergic blocker drug or digoxin. Ventricular arrhythmias may occur in the pregnant women with cardiomyopathy, congenital heart disease, valvular heart disease, or mitral valve prolapse. Termination of ventricular arrhythmias can usually be achieved by intravenous lidocaine or procainamide or by electrical cardioversion. Amiodarone is not safe for the fetus. Beta-blocker therapy must be continued during pregnancy and postpartum period in women with long QT syndrome and torsade de pointes.     

Recommendations for participation in competitive sport and leisure-time physical activity in individuals with cardiomyopathies, myocarditis and pericarditis.

Several relatively uncommon, but important cardiovascular diseases are associated with increased risk for acute cardiac events during exercise (including sudden death), such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and myo-pericarditis. Practising cardiologists are frequently asked to advise on exercise programmes and sport participation in young individuals with these cardiovascular diseases. Indeed, many asymptomatic (or mildly symptomatic) patients with cardiomyopathies aspire to a physically active lifestyle to take advantage of the many documented benefits of exercise. While recommendations dictating the participation in competitive sport for athletes with cardiomyopathies and myo-pericarditis have recently been published as a consensus document of the European Society of Cardiology, no European guidelines have addressed the possible participation of patients with cardiomyopathies in recreational and amateur sport activities. The present document is intended to offer a comprehensive overview to practising cardiologists and sport physicians of the recommendations governing safe participation in different types of competitive sport, as well as the participation in a variety of recreational physical activities and amateur sports in individuals with cardiomyopathies and myo-pericarditis. These recommendations, based largely on the experience and insights of the expert panel appointed by the European Society of Cardiology, include the most up-to-date information concerning regular exercise and sports activity in patients with cardiomyopathies and myo-pericarditis.     

Residual atrial fibrillation and clinical consequences following postoperative supraventricular arrhythmias

AIMS: This retrospective study investigated whether the supraventricular arrhythmias (SVA) observed during cardiac surgery are limited to or persist beyond the postoperative period, their clinical consequences and whether they are influenced by preoperative and postoperative factors. METHODS: A total of 375 patients undergoing elective bypass graft surgery over a 15-month period by three surgeons were included. All patients had their preoperative medications continued to the day of surgery and prophylactic anti-arrhythmic medications were not used in any of the cases. Standard anaesthetic techniques were used. Rhythm disturbances were diagnosed by ECG. The arrhythmias were treated medically or by cardioversion. All patients were followed up for 6 months. RESULTS: Postoperative SVA occurred in 25% of patients. The commonest arrhythmia was atrial fibrillation (89.4%), followed by atrial flutter (6.4%) and supraventricular tachycardia (4.2%). In 89. 8% of the cases, the arrhythmias occurred within the first four postoperative days with a maximum incidence on the second day (27. 7%). Atrial fibrillation was still present in 50% of patients at hospital discharge and in 39% at 6 months follow up. Patients with arrhythmias had a prolonged hospital stay (7.7+/-2.6 vs. 6.0+/-2.6 days; P<0.05). There was no hospital mortality in the study and the incidence of postoperative stroke was equal in the sinus rhythm and arrhythmia patients (1.1%). SVA were more frequent when cardioplegia was used to protect the heart (32%) than with intermittent ischaemia (9%; P<0.001). At 6 months follow up, the patients receiving cardioplegia also had a higher prevalence of atrial fibrillation than those operated with intermittent ischaemia (41% vs. 22%; P<0. 05). The incidence of SVA and persistence of atrial fibrillation was unrelated to other preoperative and intraoperative factors. CONCLUSION: Postoperative supraventricular arrhythmias have a long-lasting effect on cardiac rhythm: patients with SVA have a high probability of remaining in atrial fibrillation at hospital discharge and 6 months after surgery. The occurrence of atrial fibrillation seems to be influenced by the type of myocardial protection used but this does not appear to exert harmful effects.     

Computer diagnosis of supraventricular and ventricular arrhythmias. A new esophageal technique.

Computerized arrhythmia monitors recognize only a few of the significant arrhythmias and generally fail to detect arrhythmias of supraventricular origin. This is because conventional surface leads, which are sufficient for QRS recognition, are highly inadequate for automated P-wave detection. A new two-lead system, which includes a swallowable capsule-electrode for esophageal monitoring of atrial activity, is used in an on-line arrhythmia monitor. Three interval measurements (AA, AR and RR) and a QRS shape measurement provide the foundation for a detailed interpretation of each beat. Building on the single-beat analysis, a contextual diagnostic algorithm then recognizes and reports on-line the following arrhythmias: couplets, bigeminy, trigeminy, ventricular tachycardia, supraventricular tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia with retrograde conduction to the atria, first-degree block, second-degree block, Wenckebach periodicity, advanced block, third-degree block and sinus bradycardia.     

Clinical experience with propafenone for cardiac arrhythmias in the young

Seventy-two children were treated with propafenone between 1980and 1990. The mean age was 34 months (range 0.192). Arrhythmiasincluded atrioventricular re-entry tachycardia in 32 patients(44%), atrial flutter in 16 (22%), atrial or junctional ectopictachycardia in 10 (14%), atrial re-entry tachycardias in three(4%) and ventricular arrhythmias in 11 patients (16%). The efficacyof oral treatment was good in patients with atrio-ventricularre-entry tachycardia (80%), atrial flutter (71%) and atrialectopic tachycardia (83%); it was poor in ventricular arrhythmias(40%). The mean oral dose was 13.5 mg. kg^–1. day^–1. Dosageand serum levels of propafenone did not differ whether the patientswere treated successfully or not. No correlation between dosageand serum level was observed. Intravenous propafenone administrationwas only partially successful in suppressing supraventriculartachycardias (6 of 11 patients). The presence of a congenital heart defect and the time of onsetof the arrhythmias had a significant influence on the efficacyof propafenone. Better results were observed in patients withnormal hearts and in whom onset of arrhythmia was pre-natal(success 80%) as well as in patients with arrhythmias seen earlyafter surgery for congenital heart defects (success 87%). Success(65%) was also observed in patients without congenital heartdefects and postnatal onset of supraventricular arrhythmias.Patients with ventricular or supraventricular arrhythmias lateafter corrective surgery showed the poorest response (31%).     

The predictive value of electrophysiologic studies in untreated patients with Wolff-Parkinson-White syndrome

The ability of invasive electrophysiologic studies to predict future arrhythmic events in patients with minimally symptomatic Wolff-Parkinson-White syndrome is not known. To assess this ability, 42 patients with evidence of atrioventricular (AV) pre-excitation on the surface electrocardiogram underwent electrophysiologic studies and were then followed up as outpatients taking no medications. The patients were classified into three groups on the basis of prestudy symptoms: group I, 15 asymptomatic patients; group II, 10 patients with infrequent symptoms but no documented arrhythmias; and group III, 17 patients with one documented episode of supraventricular tachycardia or atrial fibrillation, or both. At electrophysiologic study, the number of patients with short anterograde accessory pathway effective refractory periods and rapid ventricular responses during induced atrial fibrillation did not differ statistically among the three groups. During a mean follow-up period of 7.5 +/- 4.9 years, 11 of the 42 patients had documented arrhythmias: 2 patients from group II and 2 patients from group III had supraventricular tachycardia and 7 patients from group III had atrial fibrillation. All nine patients from group III with subsequent arrhythmias had had clinical atrial fibrillation before study. No patient from group I had an arrhythmia during follow-up. There were no episodes of ventricular fibrillation or sudden cardiac death during follow-up in any of the patients. The only predischarge variables that correlated with the subsequent occurrence of arrhythmias were a history of documented arrhythmias before electrophysiologic study (p less than 0.01) and inducible supraventricular tachycardia at electrophysiologic study (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Conversion of supraventricular arrhythmias to sinus rhythm using flecainide

We evaluated the efficacy of flecainide acetate (given intravenouslyto a maximal dose of2 mg kg^–1 and then orally in a doseof 100 mg b.d. or 100 mg t.d.s.) in the conversion to sinusrhythm of 50 patients exhibiting supraventricular arrhythmias(39 with atrial fibrillation, 6 with atrial flutter, 4 withsupraventricu tachycardia and onewith supraventricular tachycardiain association with the Wolff—Parkinson—White syndrome).Conversion was achieved in 36 patients (72%) (29 cases withatrial fibrillation, 4 cases with supraventricular tachycardia,2 cases with atrial flutter and one case with Wolff—Parkinson–Whitesyndrome), over a mean period of 7.4 ± 9 h. The patientsin which conversion was achieved had arrhythmias which had beenin existence for a shorter time (5.3 ± 9.8 days) thanthose in which conversion was not achieved (16.7 ± 26.2days) (P<0.01). The mean dosage of flecainide used to achieveconversion was 2.5 ± 2.36 mg kg^–1. Flecainide appearsto be an effective agent for the conversion to sinus rhythmof atrial fibrillation and supraventricular tachycardias. Itsefficacy in cases of atrial flutter has not yet been demonstrated.     

Comparison of lidoflazine and quindine in prophylactic treatment of arrhythmias.

The efficacy of quinidine versus lidoflazine therapy was compared in the maintenance of sinus rhythm after electrical cardioversion for atrial flutter or fibrillation in a group of 35 patients. Both quinidine and lidoflazine were relatively ineffective in maintaining sinus rhythm after cardioversion. Lidoflazine was also used to prevent supraventricular and ventricular tachycardias in a miscellaneous group of patients; one of these with paroxysmal supraventricular tachycardia developed runs of venttricular tachycardia soon after starting lidoflazine. The trial was stopped after 4 patients died while receiving lidoflazine, on the suspicion that their deaths may have been related to drug-induced arrhythmias. The arrhythmogenic potential of lidoflazine when used in patients with supraventricular arrhythmias constrasts with reports of its apparent safety in large numbers of patients with angina pectoris.     

Comparison of lidoflazine and quindine in prophylactic treatment of arrhythmias.

The efficacy of quinidine versus lidoflazine therapy was compared in the maintenance of sinus rhythm after electrical cardioversion for atrial flutter or fibrillation in a group of 35 patients. Both quinidine and lidoflazine were relatively ineffective in maintaining sinus rhythm after cardioversion. Lidoflazine was also used to prevent supraventricular and ventricular tachycardias in a miscellaneous group of patients; one of these with paroxysmal supraventricular tachycardia developed runs of venttricular tachycardia soon after starting lidoflazine. The trial was stopped after 4 patients died while receiving lidoflazine, on the suspicion that their deaths may have been related to drug-induced arrhythmias. The arrhythmogenic potential of lidoflazine when used in patients with supraventricular arrhythmias constrasts with reports of its apparent safety in large numbers of patients with angina pectoris.     

Cardiac arrhythmias in arterial hypertension

Patients with arterial hypertension frequently manifest various cardiac rhythm disturbances, ranging from bradyarrhythmias to supraventricular premature beats, atrial fibrillation, or other supraventricular and ventricular tachyarrhythmias. These cardiac arrhythmias may either cause symptoms or be completely asymptomatic, depending on the underlying cardiac function. Degenerative electrical disease and left ventricular hypertrophy constitute the principal pathophysiological mechanisms. This review summarizes all important existing evidence on cardiac arrhythmia manifestation in the setting of arterial hypertension, and it highlights known underlying pathophysiological mechanisms and therapeutic considerations.     

Mechanism of action of sotalol in supraventricular arrhythmias

Sotalol has a virtually unique antiarrhythmic profile in that it combines the properties of the Class II beta-blocking agents with the Class III properties that prolong repolarization. The Class II action exerts a marked effect on atrioventricular nodal conduction and makes sotalol a suitable drug for the treatment of adrenergic-induced supraventricular tachycradias. Sotalol helps to prevent or slow supraventricular arrhythmias involving the atrioventricular node as part of a reentrant pathway and also helps to control the ventricular rate during supraventricular arrhythmias conducted to the ventricles over the normal atrioventricular pathway. The capacity of conduction of accessory pathways is diminished by sotalol, thereby decreasing the ventricular rate during atrial fibrillation in the Wolff-Parkinson-White syndrome. The effects of sotalol on conduction of the cardiac impulse (Class I effects) have been probably overlooked and those on true refractoriness (Class III effects) overestimated.     

Ventricular and supraventricular arrhythmias in clinically silent right ventricular infarction

To study the relationship between clinically silent right ventricular infarction and the incidence of a-v block, atrial and ventricular arrhythmias, 100 patients with inferior wall myocardial infarction underwent equilibrium gated radioisotopic angiocardiography. Fifty-four of them had radioisotopic evidence of right ventricular involvement and 43 (80%) of them had a-v block and/or supraventricular arrhythmias during the acute phase of the infarct, while only 10 (22%) of the 46 patients without right ventricular involvement did. As regards the incidence of ventricular tachyarrhythmias, 14 (26%) patients with right ventricular involvement had ventricular tachycardia and/or fibrillation, while only one patient without right ventricular involvement had ventricular tachycardia, and no patients had ventricular fibrillation. Moreover, V4R-precordial lead showed a sensitivity in predicting the risk of developing a-v block/supraventricular arrhythmias and ventricular tachyarrhythmias of 0.84 and 0.79, respectively. Therefore, right ventricular involvement should be suspected when atrial arrhythmias, a-v block and ventricular tachyarrhythmias are found in early acute inferior wall myocardial infarction. On the other hand, when right precordial lead V4R in early acute inferior infarction shows ST-elevation and/or a QS pattern, the sudden occurrence of these arrhythmias should be suspected, and possibly prevented.     

Management of cardiac arrhythmias during pregnancy

Introduction

Pregnancy can precipitate or exacerbate cardiac arrhythmias. Management of those arrhythmias is not very different from that in non-pregnant women.

Objective

In this review we tried to specify factors which favour arrhythmias in pregnant women and to show their specific management.

Methods

We carried out a search through PubMed using as keywords: pregnancy, cardiac arrhythmias, antiarrhythmics.

Results

Hemodynamic perturbations, direct electrophysiological effects of hormones and underlying heart disease are potential factors that can promote arrhythmias in pregnancy. Usually, no drug therapy is needed for the management of supraventricular or ventricular premature beats but potential promoting factors should be eliminated. In paroxysmal supraventricular tachycardia, vagal maneuvers should be tried firstly. Adenosine could be used if vagal maneuvers are ineffective. In pregnant women with atrial fibrillation, the goal of treatment is the conversion to sinus rhythm or the control of ventricular rate. Ventricular arrhythmias are usually uncommon during pregnancy and often occur in the absence of structural heart disease and are responsive to drug therapy. Symptomatic bradycardia rarely complicates pregnancy and its management does not differ from that in non-pregnant women.     

The diagnosis and management of supraventricular tachycardia by transesophageal cardiac stimulation and recording

Twenty-two consecutive patients underwent esophageal stimulation and recording for the diagnosis and management of supraventricular tachycardia. In 13 of these patients, the resting electrocardiogram was normal and in nine it showed pre-excitation. Of the 13 patients with a normal resting electrocardiogram, supraventricular tachycardia was initiated in all. Seven patients had a ventricular-to-atrial interval greater than 70 ms during supraventricular tachycardia suggesting the presence of a concealed accessory pathway, and six patients had a ventricular-to-atrial interval less than 70 ms during supraventricular tachycardia suggesting reentry within the atrioventricular node. Supraventricular tachycardia was initiated in four of nine patients with pre-excitation on the resting electrocardiogram and the accessory pathway was confirmed by a ventricular-to-atrial interval of greater than 70 ms during supraventricular tachycardia in these four patients. Atrial fibrillation was initiated in eight of the nine patients with pre-excitation on the resting electrocardiogram and the shortest R-R interval during atrial fibrillation was measured. The response to therapy was assessed in seven of these nine patients by further measurement of the shortest R-R interval during atrial fibrillation following treatment. Esophageal stimulation and recording provides a simple noninvasive procedure which can be utilized as a screening technique to identify patients with intranodal reentry and those with reentry utilizing an accessory pathway. Sequential assessment of the response to therapy, especially in those patients with pre-excitation, is of considerable value in treatment.     

Effective treatment of supraventricular arrhythmias with acebutolol.

To evaluate the antiarrhythmic efficacy of the new beta adrenergic blocking agent acebutolol, 15 monitored patients with supraventricular arrhythmias received, in double-blind fashion, an intravenous infusion of either acebutolol or saline solution after a control period. Patients treated with saline solution demonstrated no change (P greater than 0.05) in heart rate or arterial blood pressure or conversion to sinus rhythm. After administration of acebutolol, significant (P less than 0.05) reductions in heart rate were noted at 5 minutes. Peak reduction occurred at 10 to 30 minutes and correlated with maximal acebutolol plasma concentrations, antiarrhythmic activity persisted for 24 hours. Mild reductions in systolic blood pressure were observed in the majority of patients. Two patients with atrial fibrillation and one with multifocal atrial tachycardia had conversion to sinus rhythm. Frequent premature atrial complexes noted in one patient were greatly suppressed after administration of the drug. In the nine patients with clinical evidence of chronic obstructive lung disease acebutolol was well tolerated. Adverse reactions were limited to transient dyspnea in one patient with prior heart failure and a decrease in systolic blood pressure to less than 90 mm Hg in three patients who remained asymptomatic. In the patients studied, acebutolol was an effective agent for the treatment of supraventricular arrhythmias and appeared to be of special value in those with chronic obstructive lung disease.