Validity of myocardial oxygen consumption parameters

Abstract

The purpose of this study was to examine any reported indices for estimating myocardial oxygen consumption (MVO2) under uniform experimental conditions at maximal variation of hemodynamics and MVO2. One hundred sixty-two steady states were analyzed in 10 closed-chest dog experiments. Myocardial blood flow was directly measured by a different pressure catheter in the coronary sinus. The indirect values of MVO2 calculated from 24 indices were compared with directly measured MVO2. Throughout a wide range of hemodynamic states, the best correlate with MVO2 was found to be the additive parameter Et (r = 0.96). Any indices that do not incorporate potentially important changes of MVO2 related to both myocardial contractility and ventricular dimensions show unsatisfactory correlations with MVO2 at extreme changes of hemodynamics. Tension-time index (TTI) correlates poorly with MVO2 (r = 0.63). This result is due to the neglect of contractility. Pressure-heart rate product (P X HR) correlates with MVO2 with r = 0.86. Better results for TTI and P X HR, as reported in previous works, are reproducible by dividing our data into two groups of different inotropic states. At normal and moderate inotropic stimulation the correlation for TTI rises to r = 0.96, and for P X HR to r = 0.91. This augmentation is to be referred to the close relationship (r = 0.92) of peak ventricular pressure to maximum rate of pressure rise in this group. The additive parameter E1 is the best, both at moderate (r = 0.97) and at maximal inotropic stimulation (r = 0.87), and is to be preferred for indirect estimation of MVO2. Results are discussed with regard to the clinical application of MVO2 indices.

A quantitative comparison of functional and anti‐ischaemic effects of the phosphodiesterase‐inhibitors, amrinone, milrinone and levosimendan in rabbit isolated hearts

“…Myocardial oxygen-demand depends on heart-rate, wall tension and contractility (Baller et al, 1979 oxygen-supply in our model is the global coronary flow. The anti-ischaemic effects of milrinone or levosimendan suggest an improvement of the oxygen-demand/supply balance.…”

Dipyridamole Test in Angina Pectoris: Diagnostic Value and Pathophysiological Implications

“…Increased cardiac work may cause ischemia through an imbalance between increased myocardial ox ygen demand and fixed supply. This mecha nism does not seem to play a major role in our cases, since in the positive tests at the onset of ischemic electrocardiographic changes, no significant increase of double product, which is considered a reliable index of myocardial oxygen consumption [23][24][25], was observed. Decreased blood pressure re sulting in a decrease in coronary perfusion has also been suggested as a possible cause of dipyridamole-induced ischemia; in our study, however, the electrocardiographic signs of ischemia were not preceded by any significant reduction in blood pressure.…”

Coronary Artery Flow Velocity Is Related To Lumen Area and Regional Left Ventricular Mass

“…For these studies, resting perfusion (q) was estimated by the double-product of heart rate (HR) and systolic blood pressure (SBP) from the following simple but readily available clinical relation. 6,7 (3) qϭ8ϫ{[0.7ϫ(HRϫSBP)ϫ10 Ϫ3 ]Ϫ0.4}…”