Single-beat estimation of maximal right ventricular pressure strongly correlated with observed pressure (r = 0.98 +/- 0.02), enabling assessment of contractility without changing load.
In a canine model, right ventricular maximal pressure (P(max)) can be accurately predicted from normal beats to determine ESPVR and assess ventricular contractility without altering load.
Effect estimate: r = 0.98 +/- 0.02
Assessment of right ventricular (RV) contractility from end-systolic pressure-volume relationships (ESPVR) is difficult due to problems in measuring RV instantaneous volume and to effects of changes in RV preload or afterload. We therefore investigated in anesthetized dogs whether RV ESPVR and contractility can be determined without measuring RV volume and without changing RV preload or afterload. The maximal RV pressure of isovolumic beats (P(max)) was predicted from isovolumic portions of RV pressure during ejecting beats and compared with P(max) measured during the first beat after pulmonary artery clamping. In RV pressure-volume loops obtained from RV pressure and integrated pulmonary arterial flow, end-systolic elastance (E(es)) was assessed as the slope of P(max)-derived ESPVR, pulmonary artery effective elastance (E(a)) as the slope of end-diastolic to end-systolic relation, and coupling efficiency as the E(es)-to-E(a) ratio (E(es)/E(a)). Predicted P(max) correlated with observed P(max) (r = 0.98 +/- 0.02). Dobutamine increased E(es) from 1.07 to 2.00 mmHg/ml and E(es)/E(a) from 1.64 to 2.49, and propranolol decreased E(es)/E(a) from 1.64 to 0.91 (all P < 0.05). After adrenergic blockade, preload reduction did not affect E(es), whereas hypoxia and arterial constriction markedly increased E(a) and somewhat increased E(es) due to the Anrep effect. Low preload did not affect E(es)/E(a) and high afterload decreased E(es)/E(a). In conclusion, in the right ventricle 1) P(max) can be calculated from normal beats, 2) P(max) can be used to determine ESPVR without change in load, and 3) P(max)-derived ESPVR can be used to assess ventricular contractility and ventricular-arterial coupling efficiency.
Brimioulle et al. (2003) studied Right ventricular contractility assessment. Single-beat estimation of P(max) vs. Observed P(max) during pulmonary artery clamping was evaluated on Correlation between predicted P(max) and observed P(max) (r = 0.98 +/- 0.02). Single-beat estimation of maximal right ventricular pressure strongly correlated with observed pressure (r = 0.98 +/- 0.02), enabling assessment of contractility without changing load.