title: Single-beat estimation of right ventricular end-systolic pressure-volume relationship.
abstract: 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.
authors.affiliation: Department of Intensive Care, Erasme Hospital, 808 Lennik Road, B-1070 Brussels, Belgium. serge.brimioulle@ulb.ac.be
authors.forename: Serge
authors.initials: S
authors.lastname: Brimioulle
authors.forename: Pierre
authors.initials: P
authors.lastname: Wauthy
authors.forename: Patricia
authors.initials: P
authors.lastname: Ewalenko
authors.forename: Benoît
authors.initials: B
authors.lastname: Rondelet
authors.forename: Françoise
authors.initials: F
authors.lastname: Vermeulen
authors.forename: François
authors.initials: F
authors.lastname: Kerbaul
authors.forename: Robert
authors.initials: R
authors.lastname: Naeije
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D011237:Predictive Value of Tests; D011433:Propranolol / Q000494:pharmacology; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology; D016278:Ventricular Function, Right / Q000502:physiology*; D017725:Ventricular Pressure / Q000187:drug effects / Q000502:physiology*
chemical_list: D002316:Cardiotonic Agents; D014665:Vasodilator Agents; D004280:Dobutamine; D011433:Propranolol