Effect of exercise on ventricular diastolic time in coronary artery disease

To evaluate diastolic time during uninterrupted upright exercise, 28 normal volunteers (group 1) and 12 men with coronary artery disease (group 2) were studied by ear densitography. Electromechanical systole-heart rate and diastolic time-heart rate regression equations during upright exercise were obtained from group 1. Electromechanical systole-heart rate had an inverse linear relation (electromechanical systole = 480 - 1.4 heart rate) and diastolic time-heart rate had an inverse nonlinear relation (diastolic time = 1206e-0.02 heart rate). Although there were no significant differences in electromechanical systole and diastolic time at 1 minute of exercise between patients with and without CAD, at peak exercise prolongation of electromechanical systole and consequent shortening of diastolic time in patients with CAD were observed. This disproportionate shortening of diastole with lengthening of systole at peak exercise tends to decrease myocardial perfusion and, hence, oxygen supply, while increasing myocardial oxygen demand, contributing to aggravation of ischemia in patients with CAD.