Acute electrophysiologic, hemodynamic and left ventricular effects of nifedipine and beta-blocker interactions. Maintenance of global and regional left ventricular wall motion.

To assess potential cardiac effects of nifedipine and beta-blocker interactions, 10 men receiving chronic beta-blocker therapy for angina underwent hemodynamic, electrophysiologic and left ventricular (LV) functional analyses at the time of cardiac catheterization before and after buccal administration of 10 mg of nifedipine. Although this combination is usually well tolerated, there have been occasional reports suggesting that the combination of nifedipine and beta-blocking agents may increase the likelihood of congestive heart failure, severe hypotension or exacerbation of angina. All patients had class II or III stable angina pectoris and were receiving at least 160 to 240 mg/day of propranolol or equivalent doses of beta-blocker therapy. Nifedipine produced no acute electrophysiologic changes, including heart rate, PR interval, AH interval, HV interval, sinus node recovery time or heart rate at which atrioventricular nodal block occurred. Hemodynamic effects included no significant change in mean right atrial pressure (7 +/- 1 vs 5 +/- 1 mm Hg), while mean pulmonary artery pressure decreased significantly (20 +/- 2 vs 17 +/- 1 mm Hg, p less than or equal to 0.05). In addition, LV end-diastolic pressure decreased significantly from 16 +/- 2 to 10 +/- 1 mm Hg (p less than or equal to 0.05), with a nonsignificant decrease in mean aortic pressure from 93 +/- 5 to 86 +/- 4 mm Hg. Likewise, no significant change occurred in cardiac index (3.2 +/- 0.4 vs 3.0 +/- 0.4 liters/min/m2) or systemic vascular resistance (1,157 +/- 247 vs 1,170 +/- 236 dynes/s/cm-5). Left ventricular ejection fraction (EF) was the same before and after nifedipine (73 +/- 2% vs 74 +/- 2%).(ABSTRACT TRUNCATED AT 250 WORDS)