Impact of exercise training on ventricular properties in a canine
model of congestive heart failure .
Todaka, Koji, Jie Wang, Geng-Hua Yi, Mathias Knecht, Richard Stennett,
Milton Packer, and Daniel Burkhoff.
Division of Circulatory Physiology, Department of Medicine and
Anesthesiology, College of Physicians & Surgeons, Columbia
University, New York, NY 10032
APStracts 3:0427H, 1996.
Exercise training improves functional class in patients with chronic
heart failure (CHF) via effects on the periphery with no previously
documented effect on intrinsic left ventricular (LV) properties.
However, because methods used to evaluate in vivo LV function are
limited, it is possible that some effects of exercise training on the
failing heart have thus far eluded detection. Twelve dogs were
instrumented for cardiac pacing and hemodynamic recordings. Hearts
were paced rapidly for 4 weeks. Six of the dogs received daily
treadmill exercise (CHFEX, 4.4 km/hr, 2 hrs/day) concurrent with
rapid pacing while the other dogs remained sedentary (CHFS).
Hemodynamic measurements taken in vivo at the end of 4 weeks revealed
relative preservation of dP/dtmax (2540+/-440 vs 1720+/-300 mmHg/sec,
p<0.05) and LV end-diastolic pressure (9+/-5 vs 19+/-4 mmHg,
p<0.05) in CHFEX compared to CHFS, respectively. The hearts
were then isolated and cross perfused for in vitro measurement of
isovolumic pressure-volume relations; these results were compared to
those of 6 normal dogs (N). Systolic function was similarly depressed
in both groups of pacing animals (Ees values of 1.66+/-0.47 in CHFS,
1.77+/-0.38 in CHFEX and 3.05+/-0.81 mmHg/ml in N, with no changes in
Vo). Diastolic myocardial stiffness constant, k, was elevated in CHFS
and was normalized by exercise training (32+/-3 in CHFS, 21+/-3 in
CHFEX , 20+/-4 in N). Thus, daily exercise training preserved in vivo
hemodynamics during 4 weeks of rapid cardiac pacing and was
accompanied by a significant change in diastolic myocardial stiffness
in vitro. These findings suggest that changes in heart function may
contribute to the overall beneficial hemodynamic effects of exercise
training in CHF by a significant effect on diastolic properties.
Received 15 July 1996; accepted in final form 24 September 1996.
APS Manuscript Number H626-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996