Effects of Reserpine Therapy on Cardiac Output and Atrioventricular Conduction During Rest and Controlled Heart Rates in Patients with Essential Hypertension

The effects of long-term reserpine therapy (1) on cardiac output during rest and induced atrial tachycardia and (2) on atrioventricular (A-V) conduction were examined in a group of eight men with previously untreated essential hypertension. The patients were studied before and after 20 to 205 days of reserpine therapy. All studies were performed in the cardiopulmonary laboratory with the patients supine. Heart rate was controlled with a transvenous pacing catheter and a battery-powered pacemaker. After therapy six of six patients had a fall in cardiac output with a statistically significant difference (P<0.001) between the means of paired pre-reserpine and reserpine cardiac outputs during both rest and paced tachycardia. At comparable heart rates, atrioventricular conduction increased in six of eight patients following reserpine, and a significant difference (P<0.05) was evident when the means of pooled paired pre-and post-reserpine A-V conductions were compared.This study indicates that therapeutically administered reserpine in a hypertensive population (1) may significantly lower cardiac output at rest with no further decrease during induced atrial tachycardia, and (2) may increase A-V conduction and enhance second degree heart block during induced atrial tachycardia.