Effects of Isometric Exercise on Cardiac Performance

Abstract

Twenty-two patients with heart disease performed a standard isometric exercise, sustained handgrip, during the course of diagnostic cardiac catheterization. During handgrip an increase in mean arterial pressure (average 87 to 104 mm Hg) was noted in all patients. Coronary sinus blood flow and myocardial O 2 consumption increased (average 45%) in all patients so monitored. Systemic vascular resistance increased in 19 patients, in contrast to the response reported in normal volunteers. The relation between left ventricular stroke-work index and LVEDP (left ventricular function curve) during the control state and during the fourth minute of sustained handgrip provided a simple estimate of left ventricular reserve and correlated well with the New York Heart Association functional classification of the patient studied. Patients with good reserve had a rise in stroke-work with little or no change in LVEDP. Patients with poor reserve had a fall in stroke-work together with a substantial rise in LVEDP. It is concluded that the stress imposed by sustained handgrip provides a simple test for the evaluation of left ventricular reserve.