Increased left ventricular emptying at maximal exercise after reduction in afterload

• Published in: Circulation (New York, N.Y.) N.Y.), 1984-03, Vol.69 (3), p.492-496
• Main Authors: ANDERSEN, K, VIK-MO, H
• Format: Article
• Language: English
• Subjects: Adult; Antiarythmic agents; Biological and medical sciences; Blood Pressure - drug effects; Cardiac Output - drug effects; Cardiovascular system; Echocardiography; Exercise Test; Heart Rate - drug effects; Humans; Male; Medical sciences; Myocardial Contraction - drug effects; Nifedipine - pharmacology; Pharmacology. Drug treatments; Physical Exertion; Space life sciences; Stroke Volume - drug effects; Time Factors
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.69.3.492

Twelve healthy men were studied by M mode echocardiography during exercise to investigate the effect of afterload reduction on left ventricular function at maximal exertion. They performed two maximal exercise bicycle tests 4 hr apart while in the semisupine position and were given 20 mg nifedipine sublingually 30 min before the second test. During the first test end-systolic dimension decreased (p less than .01) and fractional shortening increased from rest to peak exercise (p less than .01), while end-diastolic dimension did not change significantly. At maximal exercise systolic blood pressure was lower after nifedipine than in the preceding control test (202 +/- 10 [mean +/- SD] vs 212 +/- 14 mm Hg; p less than .01), while heart rate was not significantly changed (168 +/- 15 vs 162 +/- 13 beats/min). End-systolic dimension was lower (25.6 +/- 3.3 vs 28.8 +/- 4.2 mm; p less than .01) and fractional shortening higher (50.7 +/- 6.0% vs 45.3 +/- 7.0%; p less than .01) while end-diastolic dimension was unchanged (52.3 +/- 1.9 vs 52.4 +/- 2.6 mm). Our data indicate increased left ventricular emptying at maximal exercise after nifedipine, most probably due to reduction in afterload.