title: Preload-adjusted maximal power of right ventricle: contribution of end-systolic P-V relation intercept.
abstract: To assess whether preload-adjusted maximal power (PAMP), which is calculated as W(max)/V (where W(max) is maximal power and V(ed) is end-diastolic volume with beta = 2) is an index of right ventricular (RV) contractility, we measured RV pressure (P) and volume (V) and pulmonary artery pressure and flow in 10 dogs at baseline and after inotropic stimulation. PAMP was derived from steady-state data, whereas the slope (E(es)) and intercept (V(d)) of the end-systolic P-V relationship were derived from data obtained during vena caval occlusion. Inotropic stimulation increased E(es) (from 0.96 +/- 0.25 to 1.62 +/- 0.28 mmHg/ml; P < 0.001) and V(d) (from -3.0 +/- 17.2 to 12.4 +/- 10.8 ml; P < 0.05) but not PAMP (from 0.24 +/- 0.10 to 0.36 +/- 0.22 mW/ml(2); P = 0.09). We found a strong relationship between the optimal beta-factor for preload adjustment and V(d). A corrected PAMP, PAMP(c) = W(max)/(V(ed) - V(d))(2), which incorporated the V(d) dependency, was sensitive to the inotropic changes (from 0.23 +/- 0.12 to 0.54 +/- 0.17 mW/ml(2); P < 0.001) with a good correlation with E(es) (r = 0.88; P < 0.001).
authors.affiliation: Hydraulics Laboratory, Institute of Biomedical Technology, Ghent University, Belgium. patrick.segers@rug.ac.be
authors.forename: Patrick
authors.initials: P
authors.lastname: Segers
authors.forename: H Alex
authors.initials: HA
authors.lastname: Leather
authors.forename: Pascal
authors.initials: P
authors.lastname: Verdonck
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Sun
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Wouters
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002306:Cardiac Volume / Q000502:physiology; D004285:Dogs; D008955:Models, Cardiovascular; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology*