Diastolic Time during Static and Dynamic Exercise in Myocardial Infarction

Abstract

To evaluate the difference in the response of DT in the early phase of static (sustained weight load) and dynamic (treadmill) exercise, the relation of DT and HR was studied by ear densitography in 11 patients with myocardial infarction. None of the patients had an ischemic electrocardiographic response during exercise. Despite an increase in HR and the pressure-HR product with both types of exercise, the pressure-HR product was significantly higher at three minutes of dynamic exercise, which was associated with a significant lengthening of left ventricular ejection time. Diastolic blood pressure rose significantly during static exercise, but it remained unchanged with dynamic exercise. Electromechanical systole and HR had a linear inverse relation at three minutes of exercise, and DT and HR had a nonlinear inverse relation (DT = e7.29-0.0156 x HR, and DT = e7.07-0.0142 x HR for static and dynamic exercises, respectively). A significant prolongation of QS2 with a consequent shortening of DT (p less than 0.05) was observed in dynamic exercise. In addition to a higher pressure-HR product, the disproportionate shortening of diastole in the early phase of dynamic exercise has a potential for initiating imbalance of myocardial oxygen supply and demand.