Measurement of coronary flow in local areas of myocardium using xenon 133.

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Abstract
Kety''s technique for measuring local flow was evaluated in the normal heart in 25 anesthetized dogs. Saline containing xenon 133 or 131I antipyrine was injected into the free wall of the left ventricle and count rate over the injection site was recorded during washout by an external counter. The semilog replot of the decay was variable in the first 10-40 sec. Flow-to-volume ratios were calculated from the subsequent part of the curve which was exponential down to approximately 3% of the initial count rate. Increasing injection volume to 0.5 ml caused no significant difference in estimates. Values were uninfluenced by temperature of injectate in the range 0[degree]-38[degree]C. There was no significant difference between values based on xenon and antipyrine. When flow was increased, flow estimated by xenon increased less than flow indicated by a flowmeter. Following deep injection, washout was significantly slower (20%) than following superficial injection. There was no consistent difference between injections made at different sites on the left ventricular wall, and for injections of the same depth, the standard deviation of paired estimates of flow was 15% of the mean.