Afterload reduction by nifedipine--the acute haemodynamic response to exercise in hypertensive subjects

In 16 people with essential hypertension, heart rate (HR), blood pressure (BP) and relative cardiac volumes were measured at rest and during submaximal upright exercise before and after 10 mg of sublingual nifedipine using radionuclide ventriculography. In 10 patients who had had no previous therapy (BP 152/103 +/- 5/3 mmHg) nifedipine produced a fall in BP of 6/12 +/- 3/3 mmHg (SEM) and a rise in HR of 15 +/- 5 bpm (P less than 0.001). This was associated with a rise in LVEF of 0.07 +/- 0.02 (P less than 0.005) and in cardiac output of 44 +/- 9%, presumably as a result of ventricular offloading. The cardiac response to exercise given the different starting values, was unchanged by nifedipine. Thus the HR was 101 +/- 6 bpm at rest after nifedipine and on exercise rose to 124 +/- 6 bpm (P less than 0.001): stroke volume was +22 +/- 8% at rest after nifedipine and rose to +43 +/- 12% on exercise. Thus cardiac output which had increased by 44 +/- 9% after nifedipine increased by 100 +/- 10% from the initial value. In 6 patients pre-treated with atenolol (100 mg) and with similar resting BP (158/101 +/- 5/4 mmHg) there was a fall in BP of 32/15 +/- 3/2 mmHg after nifedipine which was greater than in the previously untreated group (P less than 0.01). In this group HR increased by 8 +/- 3 bpm (P less than 0.05). Following nifedipine the exercise response was similar given the different starting values.(ABSTRACT TRUNCATED AT 250 WORDS)