Characterization of the human right ventricular pressure-volume relation: Effect of dobutamine and right coronary artery stenosis

Abstract

Right ventricular function was assessed in 15 patients using right ventricular pressure-volume loops. Right ventricular pressure using a micromanometer-tipped catheter, thermodilution cardiac output and gated blood pool scintigrams were simultaneously obtained. To help isolate the right ventricle, a slant hole collimator was used. The measurements were repeated during dobutamine infusion, which was titrated so there was minimal change in systemic pressure and heart rate. The right ventricular pressure-volume loop resembles the usual left ventricular loop except that the isovolumic contraction phase is often not as distinct, and right-sided ejection may continue well beyond right ventricular peak systolic pressure. Systolic but not diastolic function improved with dobutamine administration. There was no significant difference in right ventricular systolic function (ejection fraction, stroke work index, stroke volume index and cardiac index) or in end-diastolic volume index between patients without (Group I) and with (Group II) significant right coronary artery stenosis. However, there was a small but significant difference in right ventricular end-diastolic pressure (5.3 +/- 2.5 and 8.1 +/- 1.8 mm Hg [p less than 0.05]) for Group I and II, respectively. Thus, the right ventricular pressure-volume loop can be used to graphically display right ventricular function and improvement in contractility with dobutamine. The right ventricular isovolumic contraction phase and ejection phase differ from those in the usual left ventricular loop. Although there was a small difference in right ventricular end-diastolic pressure in patients with and without right coronary artery stenosis, the right ventricular pressure-volume loop did not provide additional discriminatory information between these two groups of patients.