Effect of increased coronary venous pressure on left ventricular function in sheep

We studied the effect of increased coronary venous pressure (Pcv) on left ventricular (LV) function in nine anesthetized open-chested sheep. Pcv was increased by inflating a balloon in the coronary sinus. LV function was estimated by measuring maximum rate of change in LV pressure (dP/dt max) and LV end-diastolic pressure (LVEDP). Left anterior descending (LAD) coronary artery blood flow was measured with an electromagnetic flow probe. A control group (n=6) was studied similarly except that Pcv was not elevated. After completion of the experiment, LV wet/dry weight ratios were measured to estimate LV myocardial water content. The balloon inflation increased Pcv from 8.6+/-1.1 to 23.8+/-1.7 mmHg (mean+/-SEM), which decreased dP/dt max from 1611+/-236 at baseline to 1041+/-210 after 120 min of increased Pcv (P < 0.05). The dP/dt max in the control group did not change significantly. Heart rate, LAD flow, LVEDP, and aortic pressures were similar in two groups but the LV water content was significantly higher (P < 0.05) in the experimental group (76.2+/-1.0 vs. 79.1+/-0.5%). These data suggest that acute increases in Pcv result in LV dysfunction and that coronary vascular congestion and myocardial edema may, at least in part, be responsible for this finding.