Application of end-systolic pressure-volume and pressure-wall thickness relations in conscious XXXX .

@entity235 @entity452 @entity101 @entity1169
The usefulness of end-systolic measures of ventricular function was compared with that of standard contractility indexes in conscious @entity235 . End-systolic relations between left ventricular pressure and volume and between pressure and wall thickness were analyzed in @entity235 previously instrumented with ultrasonic crystals. Progressive angiotensin infusions were used to generate computer-averaged pressure-volume and pressure-wall thickness loops. Both relations were linear in every study and highly reproducible. With low and high dose @entity452 , the end-systolic pressure-volume relations were significantly displaced, with @entity101 and inconsistent changes in intercept. This relation was more useful than the ejection fraction for detecting contractility increases at different afterloads, but it showed no advantage over maximal left ventricular dP/dt at all ranges of preload and afterload. The end-systolic pressure-volume relations were insensitive for detecting mild decreases in inotropic state produced by @entity1169 , and maximal dP/dt was superior for detecting such mild acutely reduced contractility. The end-systolic pressure-wall thickness relations showed displacement with @entity452 , although slope and intercept changes were not significant; these relations did not detect mild decreases in contractility produced by @entity1169 . It is concluded that the end-systolic pressure-volume relation and a simplified end-systolic measure using pressure and wall thickness provide sensitive, load-independent and reproducible approaches for defining acute increases in left ventricular contractility in conscious animals. Maximal dP/dt was equally effective for defining these increases in contractility and more sensitive for detecting slight acute decreases in contractility.
