BASIC DETERMINANTS OF EPICARDIAL TRANSUDATION

Myocardial edema formation, which has been shown to compromise cardiac function, and increased epicardial transudation (pericardial effusion ) have been shown to occur after elevation of myocardial venous and ly mphatic outflow pressures. The purposes of this study were to estimate the hydraulic conductance and osmotic reflection coefficient for the epicardium and to determine the effect of coronary sinus hypertension and cardiac lymphatic obstruction on epicardial fluid flux (J(V,e)/A(e )). A Plexiglas hemispheric capsule was attached to the left ventricul ar epicardial surface of anesthetized dogs. J(V,e)/A(e) was determined over 30-min periods for three intracapsular pressures (-5, -15, and - 25 mmHg) and two intracapsular solutions exerting colloid osmotic pres sures of 7.0 and 2.0 mmHg. Hydraulic conductance was estimated to be 3 .7 +/- 0.5 mu l.h(-1).cm(-2).mmHg(-1). An osmotic reflection coefficie nt of 0.9 was calculated from the difference in J(V,e)/A(e) of 16.5 +/ - 8.4 mu l.h(-1).cm(-2) between the two solutions. Graded coronary sin us hypertension induced a linear increase in J(V,e)/A(e), which was si gnificantly greater in dogs without cardiac lymphatic occlusion than i n those with occlusion.