Right heart failure: an ischemic model and restraint therapy for treatment.
BACKGROUND
Right heart failure is poorly understood and treated. In left heart failure, ventricular restraint can reverse pathologic left ventricular remodeling. The effect of restraint in right heart failure, however, is not known. We hypothesize that ventricular restraint can be applied selectively to the right ventricle (RV) to promote RV reverse remodeling.


METHODS
Right heart failure was induced by right coronary artery ligation in a sheep model. Eight weeks later, a saline-filled epicardial balloon was placed around the RV surface for restraint. Restraint level was defined by measuring balloon luminal pressure at end-diastole. Maximum balloon pressure was determined by the amount of balloon pressure required to decrease systemic mean arterial pressure by 10 mm Hg. We determined end-diastolic transmural myocardial pressure, indices of myocardial oxygen consumption, and RV diastolic compliance at 4 different restraint levels.


RESULTS
After coronary ligation, RV ejection fraction (EF) decreased from 0.574±0.04 to 0.362±0.03 (p<0.05). End-diastolic RV volume increased from 70.8 mL/m2±9 to 82.2 mL/m2±7 (p<0.05) by magnetic resonance imaging. After application of restraint to the RV only, RV transmural pressure decreased significantly by 27%. Greater levels of restraint also improved RV EF (0.347±0.06 to 0.473±0.05) but did not change RV end-diastolic volume.


CONCLUSIONS
A model of ischemic right heart failure was successfully created. Selective RV restraint results in improved mechanical efficiency, decreased wall stress, and improved EF. The benefits of restraint in right heart failure warrant further investigation.
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
Marisa
M
Cevasco
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
Michael
M
Kwon
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
Amy
A
Fiedler
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
Lawrence S
LS
Lee
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
Jean
J
Shiao
Department of Cardiology, Brigham and Women's Hospital, Boston, Massachusetts.
Ravi V
RV
Shah
Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts.
Andrea H
AH
Worthington
Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts.
John A
JA
Fox
Department of Cardiology, Brigham and Women's Hospital, Boston, Massachusetts.
Raymond Y
RY
Kwong
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts. Electronic address: fchen@partners.org.
Frederick Y
FY
Chen
D000818:Animals; D004195:Disease Models, Animal; D006333:Heart Failure / Q000628:therapy*; D008297:Male; D017202:Myocardial Ischemia / Q000628:therapy*; D012756:Sheep