Effects of Propranolol on Patients with Complete Heart Block and Implanted Pacemakers

Abstract

The effects of beta-adrenergic blockade with propranolol were studied in 10 patients with complete heart block and fixed rate internal pacemakers. The patients were grouped according to the absence or presence of premature systoles before propranolol was given. In the patients with premature systoles propranolol was uniformly effective in abolishing the premature systoles. Propranolol was found to increase the systemic venous pressure, to decrease the cardiac output, and to lower myocardial contractility both at rest and during exercise in both groups. Since the heart rate was fixed, it was concluded that beta-adrenergic blockade has a significant negative inotropic effect, in addition to the chronotropic effect.

Long-term control of intractable supraventricular tachycardia by ventricular pacing.

“…The group of patients in the present series differs in that AV block was not present before drug treatment, though 1 patient had sinus bradycardia alternating with supraventricular tachycardia (Case 2), and another patient had episodes of ventricular asystole precipitated by deep inspiration or by carotid sinus massage (Case 4); in this patient atropine had failed to prevent attacks of asystole or tachycardia. It has been shown (Bloomfield and Sowton, 1967;Donoso et al, 1967;Lund-Larsen et al, 1968) that cardiac output is reduced during effort when patients with fixed-rate pacemakers are given propranolol, but this has not presented a clinical problem in the present series.…”

??-Adrenergic Receptor Blocking Drugs in Cardiac Arrhythmias1

“…In this setting, unwanted bradycardia or A V conduction block resulting from {3-blockade is not a problem, although cardiac output may be reduced (Donoso et al, 1967). Frank heart failure, however, is rare in such cases and may respond promptly to digoxin and diuretics.…”

Effect of Propranolol on Oxidative Processes of Heart Muscle

“…Rather they may exert a direct depressive action on the metabolic processes of heart muscle, which is closely related to the reduction of left ventricular perform ance [3,4], Donoso et at. [1] observed a decrease of the cardiac output as well as a diminished myocardial contractility in patients with fixed heart rate due to im planted pace-makers, both at rest and during exercise. In our experimental model, propranolol provoked alterations which resemble acute hypoxia of the heart mus cle.…”

“…Available infor mation on this problem is lacking. In some studies, no statistically significant changes were found [1,17,24,29]; in others, the analysed myocardium was from failing hearts [12,22].…”