ABSTRACT
Conceptual models have been used to assess the efficacy of cardioreduction (i.e., Batista procedure) because in vivo models were not available. This study reproduces an experimental angiographic model of heart failure by placing a large pericardial patch to sphericalize the left ventricle. Patch removal restored an elliptical normal cardiac shape. Cardioreduction was evaluated in 20 mini-pigs on cardiopulmonary bypass. Myocardial protection with a beating open method was used and cardioplegia was not used. Studies were made after an LV incision (i.e., circumflex marginal artery occlusion with the Batista incision). A large pericardial patch sphericalized the left ventricle, and LV closure by patch removal restored normal cardiac shape (ellipse). Ventricular function was evaluated by inscribing Starling curves to fill the heart systolic elastance (Ees, conductance catheter), and surface echocardiogram for fiber shortening. After defining LV function in normal hearts on bypass only, an LV incision to divide the median ramus circumflex artery was made. This ventriculotomy reduced stoke work (SW) 37% +/- 4%, but did not change elastance (Ees) or SW/end-diastolic volume (EDV) significantly. Using the LV incision function as control, patch placement reduced SW 33% +/- 4%, Ees 40% +/- 3%, and SW/EDV 44% +/- 7% and decreased fiber shortening 43% +/- 5% by echocardiogram. Patch removal restored stroke work, SW/EDV, and Ees, and echocardiograms returned to normal values after LV incision. Ventricular function after patch removal was unchanged when the beating open cardioprotective technique was used. We conclude that sphericalization of left ventricular dimensions by pericardial patch placement causes cardiac failure that is relieved by restoring the ellipsoid shape by patch removal. These findings support the value of restoration of an elliptical shape by surgical cardioreduction, when the beating open ventricle is used for myocardial protection.
