AJP - Heart and Circulatory Physiology, Vol 232, Issue 2 173-H190, Copyright © 1977 by American Physiological Society
Simultaneous regional myocardial blood flows by tritiated water and microspheres
M. R. Tripp, W. Meyer, S. Einzig, J. J. Leonard, C. R. Swayze and I. J. Fox
Regional myocardial blood flow (RMF) was measured simultaneously by use of
labeled 8-mum microspheres and the constant-rate infusion of 3H2O in 22
open-chest dogs (Na pentobarbital anesthesia) under markedly different
hemodynamic conditions. Following cardiac excision, three adjacent 80-mg
tissue samples were taken from the subendocardial, mid-wall, and
subepicardial layers of quadrantal left ventricular (LV) segments of the
basal and midventricular cardiac slices, and from one segment of the apical
slice, totaling 81 samples per LV. RMF was calculated by the microsphere
reference-flow technique and by two 3H2O tissue-uptake models. Good
agreement between techniques (r=0.9-0.96) was found in comparing flows to
the myocardial layers. Using Kety's "single-mixer" model of 3H2O tissue
uptake, fairly good agreement was found between techniques in the 80-mg
tissue samples; the cofficient of variation from regression was 18.5% which
improved markedly to 12.3% when the flow values for each technique were
averaged in the three adjacent samples. Analysis of variance showed that
flow to the various LV subdivisions (layer, segment, slice) of control
animals was heterogeneous.
