IMPLICATION OF ANTERIOR SEPTAL MALALIGNMENT IN ISOLATED VENTRICULAR SEPTAL-DEFECT

Objective-The aim was to define the long term prognosis of isolated ve ntricular septal defect (VSD) with anteriorly malaligned outlet septum . Design-Cohort study. Setting-University hospital, tertiary medical c are centre. Patients-between July 1986 and June 1993, 63 patients were studied with an isolated VSD and anteriorly malaligned outlet septum (59 perimembranous; 4 muscular outlet). Main outcome measures-The diag nosis of septal malalignment, aneurysmal transformation, right ventric ular obstruction, subaortic ridge, and aortic valve prolapse was based on echocardiographic criteria, then confirmed by angiography in 33 pa tients and by surgery in 28. An actuarial curve for each event was obt ained by Kaplan-Meier non-parametric analysis and the significance was examined by log-rank test. Results-Aneurysmal transformation decrease d the size of the VSD in 52% of the patients, but was also associated with the appearance of subaortic ridge (p < 0.05). Progressive obstruc tion in the right ventricle was observed in 51%, more often in those w ithout aneurysmal transformation (p < 0.05). Aortic valve prolapse was quite common whether or not aneurysmal transformation occurred (33% a nd 23%, respectively). This was attributed to the location of the VSD and the anterior malalignment of the outlet septum. Surgery was perfor med in 28 patients at a median age of 50 months because of significant left to right shunt (n = 5), or the development of obstruction in rig ht ventricle (n = 9), aortic valve prolapse (n = 3), or combinations ( n = 11). The presence of subaortic ridge per se was not considered to be a surgical indication. Conclusions-Anteriorly malaligned VSDs have variable presentation. Careful echocardiographic evaluation is needed to identify various combinations of progressive right ventricular obst ruction, aneurysmal transformation, subaortic ridge, or aortic valve p rolapse, In extreme cases a patient may have a pathology complex compr ising right ventricular outflow obstruction, subaortic ridge, aortic v alve prolapse, and anteriorly malaligned VSD.