IMPLICATION OF ANEURYSMAL TRANSFORMATION IN ISOLATED PERIMEMBRANOUS VENTRICULAR SEPTAL-DEFECT

Defects on the membranous ventricular septum (perimembranous ventricul ar septal defect [VSD]) may spontaneously close or diminish in size by ''aneurysmal transformation'' (i.e., adherence of the tricuspid valve or adjacent tissue onto the VSD). It was recently shown that the appe arance of aneurysmal transformation may be associated with subaortic r idge, as well as left ventricular (LV)-to-right atrial (RA) shunts. In all, 877 consecutive patients with isolated perimembranous VSD were r etrospectively studied. Results of actuarial analysis showed that pati ents with a perimembranous VSD had a 98% probability of aneurysmal tra nsformation by the age of 240 months. Of these patients, the expected probabilities of developing LV-RA shunt, spontaneous closure and subao rtic ridge were 45, 35 and 6%, respectively. Patients with LV-RA shunt s had higher probabilities of developing infective endocarditis (p = 0 .002) and persistent left-to-right shunts (p < 0.001). The presence of a subaortic ridge may be accompanied by LV outflow tract obstruction (10 of 25 patients), infundibular pulmonary stenosis (n = 3), or aorti c valve deformity or aortic regurgitation (n = 5), and none of those w ith a subaortic ridge dosed spontaneously. It was confirmed that a sub stantial proportion of aneurysmal transformation of isolated perimembr anous VSD is associated with LV-RA shunts and subaortic ridges.