AJP - Heart and Circulatory Physiology, Vol 250, Issue 2 151-H158, Copyright © 1986 by American Physiological Society
Left ventricular regional work from wall tension-area loop in canine heart
Y. Goto, H. Suga, O. Yamada, Y. Igarashi, M. Saito and K. Hiramori
To quantitatively evaluate left ventricular (LV) regional work, LV
pressure-volume relation and wall tension-regional area (TA) relation were
analyzed in the excised cross-circulated left ventricle connected to a
volume servo pump system. Wall tension was calculated using Laplace's law
for a spherical model, and regional area was determined from orthogonal
segment lengths measured with pairs of ultrasonic crystals. Data were
obtained by changing LV end-diastolic volume or stroke volume before and
after dobutamine infusion and before and after global ischemia. Regional
work, assessed from the area within a TA loop during one cardiac cycle,
correlated well with simultaneously obtained LV stroke work under all of
the above experimental conditions (r = 0.90 +/- 0.09 to 0.97 +/- 0.02), and
the linear regression line was not altered by changes in stroke volume,
end-diastolic volume, or contractile state. Furthermore, measured regional
work (RWm) proved to agree closely with the predicted value (RWp)
calculated from LV stroke work and regional area [RWm = 0.91 RWp - 0.69
(mmHg . ml), r = 0.93]. Thus we conclude that TA relation may be useful for
quantitative evaluation of regional work of the LV wall.
