Effects of right and left ventricular pressure overload on left ventricular function and metabolism in dogs

The effects of acute pressure overload of the right and left ventricle on the left ventricular hemodynamics, coronary circulation, and myocardial metabolism in dogs were investigated by banding of the main pulmonary artery and by producing two models of aortic constriction with (type B) and without (type A) aortocoronary bypass. Pulmonary artery banding (left ventricular preload reduction) showed right ventriculr systolic pressure (RVSP), right ventricular end-diastolic pressure (RVEDP), and right ventricular dP/dtmax significantly elevated, but left ventricular systolic pressure (LVSP), left ventricular (dP/dtmax)/IIP slightly decreased, contrary to a slight increase of left ventricular end-diastolic pressure (LVEDP). The blood flow of the left coronary circumflex artery (CBF) was slightly decreased, but the aortic blood flow (AoF) and left ventricular work per minute (LVW) were significantly reduced. As to myocardial metabolism, the coronary arteriovenous difference (delta) of carbohydrate, mainly glucose (G) and lactate (L), increased, while that of non-esterified fatty acid (NEFA) showed a significant reduction. Aortic coarctation (left ventricular afterload increase) showed, both in types A and B, left ventricular systolic pressure, left ventricular end-diastolic pressure, and left ventricular work per minute were increased. However, aortic systolic and diastolic pressure were significantly decreased. The blood flow of the left coronary circumflex artery tended to increase in both types. The myocardial carbohydrate uptake tended to increase after aortic constriction in both types. However, the uptake of non-esterified fatty acid was increased after aortic constriction in type A, but decreased in type B. This difference in uptake of non-esterified fatty acid might be induced by the difference of the functional state of the left ventricle.