Unchanged myocardial tissue perfusion following pericardiotomy in acutely loaded cat hearts.

Myocardial tissue flow was measured by the distribution of labelled microspheres in cats which were volume-expanded by infusion of blood. Removal of the intact pericardium markedly reduced left ventricular diastolic pressure. However, despite the fact that diastolic ventricular pressure is a major determinant for myocardial tissue flow and its transmural distribution, no significant change in tissue flow occurred following pericardiotomy. Failure of tissue flow to increase in the face of lower diastolic intracavitary pressure can in this study be explained by concomitant ventricular dilatation and reduced systolic blood pressure.