The mechanical determinants of myocardial oxygen consumption in the
conscious dog.
Elbeery, Joseph R., John C. Lucke, Michael P. Feneley, George W.
Maier, Clarence H. Owen, R. Eric Lilly, Michael A. Savitt, Mark St.
J. Hickey, Stanley A. Gall, Jr, James W. Davis, Peter Vantrigt, J.
Scott Rankin, Donald D. Glower, Md.
The Department of Surgery, Duke University Medical Center, Durham,
North Carolina, The Division of Cardiothoracic Surgery, St. Thomas
Medical Center, Nashville, Tennessee, The Department of Cardiology,
St. Vincent's Hospital, Sydney, N.S.W., Australia,
APStracts 2:0099H, 1995.
A new, practical descriptor of metabolic to mechanical myocardial
energy transfer (MET), termed the virtual work model, was evaluated
in 32 conscious dogs and in 8 isolated canine hearts. An index of
total mechanical energy expenditure (TME) was calculated as the sum
of external energy (stroke work) and an internal energy index of heat
(LVEDV x LV mean ejection pressure). Physiologic comparison of TME
(x-axis) and myocardial oxygen consumption (MVO2, y-axis) yielded
highly linear MET relationships (mean r =0.93(0.07) with an average
slope of 0.86(0.39 (SD) and Y-intercept of 9.1+6.4 mW/ml myocardium.
The linear MVO2-TME relationship did not vary under steady-state
versus dynamic vena caval occlusion, increased heart rate, increased
afterload, or increased inotropic state with calcium infusion.
Compared to 5 other indices of myocardial energetics, the virtual
work model of MET was the most linear, the most practical in not
requiring determination of the end-systolic pressure-volume
relationship, and the most accurate predictor of MVO2 under normal
and altered hemodynamic conditions.
Received 4 October 1994; accepted in final form 14 February 1995.
APS Manuscript Number H891-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 March 1995.