Biventricular systolic function in young lambs subject to chronic systemic right ventricular pressure overload.
In various clinical situations of congenital heart disease, the right ventricle (RV) is subject to a chronic systemic pressure overload which affects biventricular function and may progress to the development of RV failure. Young lambs (2-3 wk old) underwent adjustable pulmonary artery banding (PAB) at systemic (aortic) level for 8 wk. Biventricular function was determined by using load-independent indexes of global ventricular contractile performance by the end-systolic pressure-volume relationship (ESPVR) using the conductance catheter at baseline and during dobutamine infusion. PAB resulted in a significant fivefold increase in RV end-systolic pressure (12-64 mmHg) and a doubling of the RV-to-left ventricular (LV) wall thickness ratio (P < 0.01). RV global contractile performance increased significantly, as indicated by an increased slope of the ESPVR. Compared with age-matched control lambs, cardiac output decreased from 2.6 to 1.6 l/min (P < 0.05) whereas heart rates were equal. In contrast with RV volume, LV volume decreased significantly after PAB (P < 0.01), whereas the LV-ESPVR slope was unchanged. In the PAB group, the RV, but not the LV, showed a reduced response to dobutamine. We concluded that chronic RV pressure overload for 8 wk results in diminished pump function despite compensatory increased RV global contractile performance.
Leeuwenburgh
B P
BP
Division of Pediatric Cardiology, Department of Pediatrics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
Helbing
W A
WA
Steendijk
P
P
Schoof
P H
PH
Baan
J
J
D000367:Age Factors; D000818:Animals; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D006332:Cardiomegaly / Q000503:physiopathology; D002316:Cardiotonic Agents / Q000494:pharmacology; D002908:Chronic Disease; D004280:Dobutamine / Q000494:pharmacology; D012756:Sheep; D013599:Systole / Q000502:physiology*; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology*; D016276:Ventricular Function; D017725:Ventricular Pressure / Q000187:drug effects / Q000502:physiology
D002316:Cardiotonic Agents; D004280:Dobutamine