AJP - Heart and Circulatory Physiology, Vol 244, Issue 2 206-H214, Copyright © 1983 by American Physiological Society
Heart rate-independent energetics and systolic pressure-volume area in dog heart
H. Suga, R. Hisano, S. Hirata, T. Hayashi, O. Yamada and I. Ninomiya
Left ventricular (LV) systolic pressure-volume area (PVA), a new measure of
total mechanical energy for the contraction, linearly correlates with its
oxygen consumption per beat (VO2) regardless of contraction mode in a
canine heart with stable chronotropism and inotropism. PVA is the area in
the pressure-volume (PV) diagram circumscribed by the end-systolic and
end-diastolic PV relation curves and the systolic segment of the PV loop
and has dimensions of energy. We investigated whether primary changes in
heart rate would affect the VO2-PVA relation. In the excised
cross-circulated canine heart with left ventricular load controlled with a
servo pump, we changed heart rate by pacing to compare the VO2-PVA
relations at low [124 +/- 17 (SD) min-1] and high (193 +/- 23) heart rates.
In 15 left ventricles, VO2 (ml O2 X beat-1 X 100 g LV-1) was (1.75 +/-
0.57) X 10(-5) PVA (mmHg X ml X beat-1 X 100 g LV-1) + 0.031 +/- 0.011 (ml
O2 X beat-1 X 100 g LV-1). The VO2-PVA relation was virtually independent
of heart rate in individual hearts. We conclude that the load-independent
VO2-PVA relationship is not affected by chronotropism in a given canine
left ventricle.
