Right ventricular tissue PO2 in dogs

Abstract

Right ventricular (RV) epicardial tissue oxygen pressure (P_tO₂) was measured polarographically by means of a platinum multiwire surface electrode on the in situ beating heart of ten anesthetized dogs prior to and after moderate (Hct 28%) normovolemic hemodilution (HD) with dextran 60. In five dogs the effect of acute occlusion of the right coronary artery (RCA) on P_tO₂ was analyzed. The P_tO₂ histograms at baseline revealed a bell-shaped configuration and a mean P_tO₂ of 46.2 ± 7.1 mm Hg which coincides with the P_tO₂ on the left ventricle (LV) reported by others. After HD mean P_tO₂ increased to 51.4 ± 8.5 mm Hg (P = 0.02) without alterations of the histogram's configuration. Hemodynamics and blood gas analyses were unchanged after HD. RCA ligature was followed by non-uniform changes in the P_tO₂ pattern. Thus, despite marked differences in external work and O₂ consumption, the P_tO₂ in both RV and LV myocardium are similar at rest. The increase of P_tO₂ in the RV at reduced Hct values, which is not seen in the LV myocardium, can be related to differences in functional capillary density between both ventricles.