Bestimmung der Masse des perfundierten Myokards in Abhängigkeit vom Perfusionsdruck mit Hilfe der Xe¹³³-Auswaschtechnik

Summary

In dog experiments the left coronary artery or the descending branch of the left coronary artery were perfused with the blood of the same dog out of an airchamber with various pressures. Mean coronary inflow was measured with an electromagnetic flowmeter. Mean transit times of Xe¹³³ were calculated from the washout-curves recorded by external counting after single intracoronary injections. The mass of the perfused myocardium was calculated as the product of mean transit time of Xe¹³³, coronary flow, and specific gravity of the myocardium.

In all experiments the mass of the perfused myocardium increased with elevation of perfusion pressure. In one group of experiments the values of the perfused myocardial mass increased continuously with elevation of perfusion pressure, whereas in a second group the mass of the perfused myocardium was relatively constant in the middle range of perfusion pressure.

Values of perfused myocardial mass obtained by excision after dye injection were higher than those calculated by the Xe¹³³-technique.

Myocardial blood flow per 100 g·min was calculated by means of mean transit times, since the calculation by means of the down slope of the semilogarithmic plot mostly gives false results.