Comparison with glyceryl trinitrate

The coronary haemodynamic effects of nifedipine and glyceryl trinitrate were compared in 22 patients undergoing investigations for suspected coronary artery disease. Myocardial blood flow was estimated by the coronary sinus thermodilution technique. In sinus rhythm nifedipine increased mean coronary sinus flow from 135 ml/min to 152 m/min, and reduced arterio-coronary sinus oxygen difference from 12*4 to 10-96 ml/100 ml without causing a significant change in coronary vascular resistance or in myocardial oxygen consumption. Glyceryl trinitrate reduced mean coronary sinus flow from 165 to 111 , mi/ myocardial oxygen consumption from 19 2 to 11 9 ml/min, and arterio-coronary sinus oxygen difference from 11-7 to 10*9 ml/100 ml. There was a rise in coronary vascular resistance from 54 355 to 74 364 dynes s cm-5.