Left ventricular function during sudden strenuous exercise.

Abstract

SUMMARY Strenuous exercise without warm-up has been shown to produce ischemia-like electrocardiographic (ECG) abnormalities in 60-70% of healthy subjects. These abnormalities appeared to be related to the development of an unfavorable myocardial supply/demand balance and, in chronically instruanented dogs, to transient decreases in coronary blood flow. A mechanism involving subendocardial ischemia has been proposed to explain the response to sudden strenuous exercise (SSE). To determine whether the response to SSE included the development of changes in myocardial pump performance typical of ischemia, left ventricular (LV) function at rest, during graded exercise and during SSE was evaluated in nine young (26.6 ± 3.4 years), welltrained male volunteers using first-pass radionuclide angiography. During graded exercise, the LV ejection fraction increased from 66.9 9.4% at rest to 73.0 + 7.1% during peak exercise, and the LV ejection rate increased from 3.36 ± 0.67 sec`at rest to 6.58 ± 1.10 sec`' during peak exercise. Segmental wall motion was normal in all studies. During SSE, the LV ejection fraction decreased in every subject, from an average 72.2 i 8.6% at rest to 57.3 ± 8.1% during exercise. The LV ejection rate remained relatively constant (3.98 0.92 sec`1 at rest vs 4.33 ± 0.74 sec`1 during SSE). No segmental wall motion abnormalities were observed during SSE; however, LV wall motion appeared to be diffusely hypokinetic during SSE. In contrast to previous reports, few ECG abnormalities were observed during SSE. These results support the hypothesis that subendocardial ischemia is an important mechanism in the response to SSE. However, the lack of ECG changes and segmental wall motion abnormalities and the relatively high absolute value of the LV ejection fraction suggest that if subendocardial ischemia occurs during SSE, it is attributable to physiologic rather than pathologic mechanisms.ISCHEMIA-LIKE electrocardiographic (ECG) changes in 60-70% of apparently healthy subjects who perform severe exercise without warm-up have been reported."' 2 These subjects had normal responses during graded exercise testing and were considered free of coronary artery disease (CAD). The development of the ischemia-like ECG changes correlated well with the relative myocardial oxygen supply/demand relationship as estimated from the ratio of the diastolic pressure time index to the tension time index (DPTI/TTI).2 Because experiments with chronically instrumented animals have indicated a transiently decreased coronary blood flow during sudden strenuous exercise (SSE),3 Barnard et al.2 suggested that the ECG responses during SSE represent subendocardial ischemia. The present investigation was conducted to determine whether SSE would induce changes in LV function similar to those in patients with CAD4-that would support Barnard's hypothesis of subendocardial ischemia during SSE.

Left Ventricular Function at Peak All-Out Anaerobic Exercise in Older Men

“…Several previous studies on the effect of sudden strenuous exercise have been shown to produce ischemia-like ECG abnormalities in young healthy subjects during sudden strenuous exercise without warm-up [12,13]. Others [2] have reported normal ECG during sudden strenuous exercise following a warm-up.…”

Diagnostic Capabilities of Exercise Testing Soon after Myocardial Revascularization Surgery

“…The technique has been described previously [10,13]. Left ventricular ejection fraction was calculated from the backgroundcorrected lime activity curve as;…”

What Maintains the Metabolic Cost at Peak Aerobic Exercise in End Stage Renal Disease Patients?

“…Functional capacity of end-stage renal disease (ESRD) patients is dramatically impaired, with changes occurring mainly in the cardiopulmonary and skeletal muscles, thus reducing maximum exercise tolerance [1,2]. Maximal oxygen uptake according to the Fick equation depends on the differential relationship between oxygen delivery (cardiac output and hemoglobin) and arteriovenous oxygen (av) O 2 .…”

“…Maximal oxygen uptake according to the Fick equation depends on the differential relationship between oxygen delivery (cardiac output and hemoglobin) and arteriovenous oxygen (av) O 2 . Therefore, an imbalance between oxygen demand-supply during exercise may expose ESRD patients to a low pH, which may alter left ventricular contractility and function [3,4] and in turn, reduce oxygen delivery to the working muscles [2].…”