Hydralazine in the management of symptomatic sinus bradycardia.

Hydralazine (Apresoline) was used to increase heart rate in 21 patients (14 hypertensive and 7 normotensive) suffering from symptomatic sinus bradycardia (SSB). Patients were assessed clinically and by 24-h ECG analysis before and after tailored increasing doses of the drug. Heart rates measured were resting (basal) rate, minimum rate during sleep, maximal rate during the day, and mean rate during the 24-h period (from hourly strips). The longest sinus pause or period of sinus arrest (when present) was also measured. Hydralazine ameliorated symptoms and produced a 20% or greater increase in heart rate in just under two-thirds of the hypertensive and half of the normotensive patients. Blood pressure decreased slightly in hypertensive but not in normotensive patients, and there were no important side-effects. Hydralazine appears to be a useful and effective drug to increase heart rate in patients with SSB.