Influence of glyceryl trinitrate during supine and upright exercise in patients with angina pectoris.

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Abstract
The clinical, ECG and circulatory effects of 0.6 mg sublingual glyceryl trinitrate were studied at rest and during treadmill and supine bicycle exercise in 16 patients with angina pectoris. Before glyceryl trinitrate, all patients experienced angina during both exercise periods. However, the heart rate and rate pressure product at angina were higher during treadmill than during supine bicycle exercise. This is considered to be the result of dimished left ventricular volume and O2 requirements in the upright posture. At rest after glyceryl trinitrate, systolic blood pressure fell and heart rate rose in each posture, the effects being more pronounced in the standing position. During exercise, when the rate pressure product at the onset of angina before glyceryl trinitrate was compared with the rate pressure product at the same work load after glyceryl trinitrate, there was no significant difference in either position (treadmill, 192 .+-. 10 vs. 203 .+-. 9; supine, 185 9 vs. 182 .+-. 8 mmHg/min .times. 10-2). In comparison with the control values before glyceryl trinitrate, exercise duration to angina after glyceryl trinitrate increased significantly in each posture. The rate pressure product at angina after glyceryl trinitrate increased significantly in comparison with the rate pressure product at angina during the control studies in each posture. The improvement in exercise tolerance and increase in rate pressure product after glyceryl trinitrate were similar during both upright and supine exercise. This could be interpreted as evidence for the predominant influence of glyceryl trinitrate on coronary perfusion. However, it is possible that similar changes in ventricular volume during exercise occurred in both positions.