Ann Thorac Surg 1996;61:1757-1758
© 1996 The Society of Thoracic Surgeons
Invited Commentary
Invited Commentary
Tirone E. David, MD
Division of Cardiovascular Surgery, The Toronto Hospital, 200 Elizabeth St, 13 EN-222, Toronto, Ont, Canada M5G 2C4
See also page 1752.
Cox and associates found that proximal rupture of the interventricular septum was the main determinant of preoperative cardiogenic shock in patients with postinfarction ventricular septal defect (VSD). Cardiogenic shock is a well-known determinant of operative mortality in these patients. These investigators reported an unusually high proportion of anterior proximal septal ruptures and posterior distal septal ruptures in patients with postinfarction VSD. In my experience most ruptures of the interventricular septum occurred in the distal half of the septum when caused by an anterior myocardial infarction, and in the proximal half of the septum when due to a posterior myocardial infarction.
Patients in whom a VSD develops after a transmural myocardial infarction have more extensive myocardial necrosis than do those in whom a VSD does not develop. In addition, those with a VSD have more extensive right ventricular infarction. Indeed, right ventricular dysfunction has been identified by many investigators to be a predictor of cardiogenic shock in these patients. This is probably the main reason why the operative mortality for repair of posterior VSD is higher than for anterior VSD. Although Cox and colleagues did not examine this issue, their operative mortality was 22% for anterior VSD and 33% for posterior VSD. I believe that their operative technique played a role in this difference in operative mortality. My colleagues and I described a type of repair whereby the infarcted left ventricle is excluded from the left ventricular cavity by suturing an endocardial patch of glutaraldehyde-fixed bovine pericardium mostly in noninfarcted muscle. No infarctectomy is performed, and in patients with posterior VSD, the base of the patch is sutured directly to the mitral annulus (see reference 18 in Cox and associates' article). This operative procedure has decreased the operative mortality quite remarkably, and the outcome of patients with postinfarction VSD has been largely determined by the amount of right ventricular necrosis in patients with posterior VSD and the amount of left ventricular necrosis in patients with anterior VSD.
