Posterior Septal Malalignment Without VSD

Malalignment of interventricular septum is generally with ventricular septal defects. Malalignment of interventricular septum without ventricular septal defect that originates from an angulation between trabecular and infundibular part of the interventricular septum was recently reported. It causes left ventricular outflow tract obstruction and aortic regurgitation because of turbulance in left ventricular outflow tract. We reported 9 patients with posterior septal malalignment without ventricular septal defect. Four patients had isolated septal malalignment, 2 had aortic coarction, 2 had pulmonary valvular stenosis and one patient had corrected transposition of great arteries. Five of them had systolic gradients in left ventricular outflow tract ranging from 10 to 70 mmHg, but four did not show subaortic systolic pressure gradient in echocardiography. Three patients with left ventricular outflow tract obstruction and one patient with severe aortic regurgitation were operated on. The LVOT/AAo ratio, an indicator of severity of left ventricular outflow tract obstruction, strongly correlated with the subaortic gradient. Two patients who had a VLOT/AAo ratio of less than 0.6 continued to have 60-70 mmHg left ventricular outflow tract pressure gradients after operation. We determined furthermore a new subaortic ridge in 2 patients and a 15 mmHg systolic gradient in one patient in the follow-up. In conclusion, septal malalignment without VSD does occur and requires elimination because of possible complications. Surgery should aim to remove turbulance and jet flow, to prevent formation of new subaortic ridge and aortic regurgitation, and avoid advers effects on the conduction system of the heart.