Septal myocardial protection during cardiac surgery for prevention of right ventricular dysfunction.

Postoperative right ventricular (RV) failure is difficult to treat and develops from functional impairment of the underlying free wall and septum. This report describes the vital importance of the ventricular septum in RV structure /function relationships, demonstrates how the helical ventricular myocardial band model defines spatial geometry of the free wall and septum to provide architectural reasons for RV dynamic action, and focuses upon pathophysiologic reasons for adverse perioperative events resulting in right ventricular failure. Myocyte fiber orientation is the key to ventricular performance in health and disease. The transverse geometry of the free wall allows constriction (bellows type motion), whereas oblique septal fiber orientation and midline septal position is essential for ventricular twisting, the vital mechanism for RV ejection against increased pulmonary vascular resistance. The septum is considered "the lion or motor of RV performance". This central muscle mass occupies approximately 40% of myocardial ventricular weight, and injury from impaired myocardial protection is a preventable event. Septal function should be the index of adequacy of myocardial protection and we will show echocardiographic evidence that the integrated cardioplegic method prevents its injury. Dysfunction of a normally functioning septum following surgical cardiac procedures calls for reevaluation of myocardial protection methods.