INTERVENTRICULAR COMMUNICATION IN COMPLETE ATRIOVENTRICULAR SEPTAL-DEFECT

Background. Little attention has been paid to whether the interventric ular communication in complete atrioventricular septal defect is diffe rent beneath the superior and inferior bridging leaflets, a feature of obvious surgical significance. Methods. We searched for a defect unde r the bridging leaflets and examined the valve morphologies in 98 auto psied and 86 surgical patients. Of the overall specimens, 27 were asso ciated with Fallot's tetralogy, and a further 20 had subaortic stenosi s, aortic coarctation, or both. In the autopsied specimens, we also me asured the degree of deficiency of the ventricular septum. Results. No communication was found under the inferior bridging leaflet in 30% (2 9 of 98) of the specimens. All 29 hearts except two without such commu nications showed an undivided inferior leaflet. In contrast, all patie nts undergoing operation except 1 had a communication beneath both bri dging leaflets (p < 0.001). The absence of a communication beneath the inferior leaflet was observed more in hearts with Fallot's tetralogy (seven of 14) or those with subaortic stenosis, aortic coarctation, or both (eight of 18) than in those without associated anomalies (14 of 66; p < 0.01). Those with a communication under the inferior leaflet s howed a greater deficiency of the inlet ventricular septum than did th ose without it (p < 0.001). Conclusions. In a certain percentage of pa tients with complete atrioventricular septal defect, there will be no communication under the inferior bridging leaflet. Surgeons should be aware of this possibility, particularly when confronted with a patient with obstruction in either ventricular outlet. (Ann Thorac Surg 1998; 66:1389-93) (C) 1998 by The Society of Thoracic Surgeons