Cardiovascular response to combined static-dynamic exercise of patients with myocardial infarction

Graded dynamic exercise-stress testing of patients with acute myocardial infarction prior to discharge from hospital has an important diagnostic and prognostic implication. Although many daily tasks involve combinations of static and dynamic exercise, little is known about cardiovascular responses during combined static-dynamic exercise.

To determine the difference between cardiovascular responses during two types of combined static-dynamic exercise (a 10 kg weight in one hand, and a 10 kg weight bearing on the shoulder).

We studied 27 male patients who had recently suffered myocardial infarction using ear densitography. The patients were divided into two groups: group 1 was comprised of 14 patients with resting left ventricular end-diastolic volumes > or = 140 ml, and group 2 was comprised of 13 patients with left ventricular end-diastolic volumes < 140 ml.

For eight patients in group 1 we detected positive electrocardiographic changes during one-hand weight-carrying exercise, but for none of these patients was there an electrocardiographic change during weight-bearing exercise. All the patients in group 2 completed both types of exercise without significant ST-segment change. Although there were no significant differences between values of any of the indices measured for the two groups during weight-bearing exercise, patients in group 1 had significantly shorter diastolic times/min (21.8 +/- 2.1 versus 25.1 +/- 2.4 s/min, P < 0.01) during one-hand weight carrying.

In addition to decrease in subendocardial coronary blood flow associated with increase in left ventricular end-diastolic volume, shortening of diastolic perfusion time during one-hand weight-carrying exercise for patients in group 1 can potentially contribute to subendocardial ischemia, which was favorably altered by bearing a weight on the shoulder.