Diastolic Time and Systolic Time Intervals during Static Exercise in the Late Hospital Phase of Acute Myocardial Infarction

Abstract

To evaluate diastolic time (DT) during static exercise, the DT-heart rate relation was studied by ear densitography in the late hospital phase of acute myocardial infarction. None of the patients had an ischemic electrocardiographic response. The patients were divided into 2 groups; group 1 comprised 12 patients with a resting left ventricular end-diastolic volume = 140 ml, and group 2 comprised 11 patients with a left ventricular enddiastolic volume < 140 ml. Electromechanical systole and heart rate had a linear inverse relation during sustained weight load exercise, while DT and heart rate had a nonlinear inverse relation (DT = e^7 51–0.019 × heart rate, DT = e^7 47–0.018 × heart rate, group 1 and 2, respectively). A significant prolongation of electromechanical systole with consequent shortening of DT (p < 0.01) was observed in group 1. In addition to a decrease in DT with increasing heart rate during a sustained weight load exercise, the disproportionate shortening of DT in patients with increased left ventricular end-diastolic volume has a potential for further impediment of subendocardial blood flow and consequently for accentuation of left ventricular dysfunction.