ACUTE INTRAVENOUS VERSUS CHRONIC ORAL-DRUG EFFECTS OF VERAPAMIL ON LEFT-VENTRICULAR DIASTOLIC FUNCTION IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

The effects of acute intravenous (i.v.) versus long-term oral(p.o.) ve rapamil administration on diastolic function were studied in 20 patien ts with hypertrophic cardiomyopathy (HCM). We used a tip manometer cat heter to record left ventricular pressure (LVP) tracings and a nuclear probe to measure LV volume changes. Infusion of verapamil resulted in an increase in time constant of relaxation (+15%, p < 0.001); LV peak filling rate, heart rate (HR), and stiffness constant of the diastoli c pressure-volume relation were unchanged. During 18-week p.o. verapam il treatment, HR decreased (-16%, p < 0.0005) and the atrial contribut ion to LV filling decreased (-27%, p < 0.05); other parameters differe d significantly from baseline values. Results demonstrate that acute i .v. versus long-term p.o. verapamil administration have different effe cts on diastolic function in HCM.