Left ventricular O2 requirements of pressure and volume loading in the normal canine heart and inaccuracy of pressure-derived indices of O2 demand.

摘要: The purpose of this study was to: 1) re-evaluate the left ventricular O2 requirements (MVO2) pressure and volume-loading; b) assess accuracy pressure-derived indices (LV) demand under pressure-loading volume-loading conditions. Using a right heart bypass preparation (heart rate 150 beats . min-1), mean arterial (7.3 to 22.9 kPa) cardiac output (0.8 6.0 litre min-1) were varied independently. Adequate supply demonstrated by normal transmural distribution blood flow, myocardial lactate metabolism, intact reactive hyperaemic responses. For equivalent increases in external work (from 2 4 joules resulted similar uptake (59% 49%, respectively, P = 0.21). MVO2 consistently greater for than at any SPTI, pressure-rate product, triple product. prediction demands these loading conditions collectively unreliable (r 30 0.42). ventricle with both highly correlated 0.82 0.99) meridional wall stress. We conclude that: have requirement appreciated previously; 2) loads volume require canine work; 3) currently used are predictors LV when varied; 4) more uniformly related