Abstract The posterior rupture of the left ventricle has been a complication recognized since the beginning of mitral valve surgery and, despite advances in cardiac surgery, the outcome of the rupture of the left ventricle has remained tragic. During mitral valve surgery, care must be taken not to traumatize the free wall of the left ventricle. On the other side, septal Myectomy is performed on hypertrophied septums to address the left ventricular outflow tract obstruction. In this article I have presented a theory that could give a part of the explanation of the resistance of the interventricular septum of surgical trauma unlike the ventricular wall.