Asian Cardiovasc Thorac Ann 1998;6:64-65
© 1998 Asia Publishing EXchange Pte Ltd
Reserpine-Induced Complete Heart Block
Mandeep Singh, DM,
Manoj Kumar Agarwala, DM,
Rajnish Juneja, DM
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Department of Cardiology Postgraduate Institute of Medical Education and Research Chandigarh, India
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For reprint information contact: Mandeep Singh, DM Department of Cardiology Postgraduate Institute of Medical Education and Research Chandigarh 160012, India Tel:91 172 54 1032 Fax:91 172 54 0401
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ABSTRACT
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Reserpine is an adrenergic neuron blocking agent that acts by depleting the stores of catecholamines. Its use as an antihypertensive has declined recently because of frequent undesirable side-effects. The side-effects are primarily extracardiac and occur at high dosages. Cardiovascular side-effects are rare and include a decrease in atrioventricular conduction, potentiation of digitalis toxicity, and possible precipitation of ventricular ectopics. We report a case of reseprine-induced complete heart block requiring a temporary pacemaker for a few days.
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INTRODUCTION
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An 80-year-old gentleman presented with a 6-month history of recurrent syncopal attacks. He was a known hypertensive for 5 years and was taking reserpine 0.2 mg twice daily for the past year. There was no history suggestive of coronary artery disease. Examination revealed a pulse rate of 37 beats per minute and intermittent cannon waves in the jugular venous column. His blood pressure was 150/80 mm Hg at admission. His electrocardiogram revealed complete heart block with an atrial rate of 88 beats per minute and a ventricular rate of 34 beats per minute. Escape rhythm was infranodal (Figure 1
). The chest radiograph was normal and biochemical parameters including urea, creatinine, and electrolytes were also normal. Temporary pacing was carried out through the left subclavian route and his antihypertensive medication was stopped. On the 4th day of admission he reverted back to normal sinus rhythm and thereafter maintained normal sinus rhythm during his hospital stay and at the 6-month follow-up (Figure 2).
An exercise test and ambulatory monitoring were carried out during his admission after he reverted to normal sinus rhythm. During the exercise test he achieved his target heart rate and there was no evidence of inducible ischemia. Ambulatory electrocardiogram monitoring for 24 hours showed intermittent right bundle branch block and normal sinus rhythm with a prolonged PR-interval. It did not show any evidence of a high degree atrioventricular block or complete heart block.
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DISCUSSION
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The use of reserpine as an antihypertensive agent has declined significantly in the last decade. This drug has fallen into disrepute because of frequently reported side-effects such as depression and gastric ulcers. These side-effects occur commonly when the dose of reserpine exceeds the currently recommended doses of 0.05 to 0.125 mg per day. Cardiac side-effects are rare with reserpine within these dosages. Our patient was receiving 0.4 mg daily and developed complete heart block that reverted to normal sinus rhythm after discontinuation of reserpine. The ambulatory electrocardiogram showed intermittent first degree atrioventricular block with right bundle branch block. The etiology of this conduction disturbance is obscure. The absence of angina and the negative exercise test make an ischemic etiology unlikely in this case.
Reserpine has been shown to influence atrioventricular conduction and in combination with digoxin can precipitate complete heart block.1,2 The exact mechanism is not known but decreased myocardial and adrenal catecholamines and enhanced central parasympathetic outflow seem to be jointly responsible.2 It is likely that a preexisting atrioventricular conduction disturbance progressed to complete heart block with reserpine in our patient. In the only previous report of complete heart block in a patient with thyrotoxic myocarditis, reserpine was not thought to be responsible for the complete heart block.3 However, in this report the authors do not mention whether reserpine was stopped and if it was, what was the temporal sequence of improvement after reserpine omission. In a large clinical trial, reserpine in a dose of 0.2 mg daily when used in combination with other antihypertensives did not adversely influence atrioventricular conduction when compared to controls.4
Our case report highlights a rare cardiac side-effect of reserpine. This drug should be recognized as the offending agent in the development of complete heart block, especially in the presence of preexisting conduction disturbances. Awareness of this and timely withdrawal can save a permanent pacemaker implantation.
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REFERENCES
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Cohen SI, Young MW, Lau SH, et al. Effects of reserpine therapy on cardiac output and atrioventricular conduction during rest and controlled heart rates in patients with essential hypertension. Circulation
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Muggla AL, Stjernholm M, Houle T. Complete heart block with thyrotoxic myocarditis. N Engl J Med
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Poblete PF, Kyle MC, Piberger HV, Frels D. Effect of treatment on morbidity in hypertension. Veterans Administration Cooperative Study on Antihypertensive Agents: effect on electrocardiograms. Circulation
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ABSTRACT
INTRODUCTION
