ACCESSORY AND ANOMALOUS ATRIOVENTRICULAR VALVAR TISSUE CAUSING OUTFLOW TRACT OBSTRUCTION - SURGICAL IMPLICATIONS OF A HETEROGENEOUS AND COMPLEX PROBLEM

Objectives. The purpose of this study was to determine the effect of a ccessory or anomalous atrioventricular valvar apparatus on relief of o utflow tract obstruction. Background. Outflow tract obstruction due to accessory tissue or anomalous attachments of the atrioventricular val var apparatus is an unusual but well-recognized problem. In addition t o obstruction, anomalous attachments of the atrioventricular valvar ap paratus may interfere,vith procedures to relieve outflow tract obstruc tion or perform outflow tract reconstruction. Methods. Since 1992, we have operated on 21 patients (median age 4 years) with systemic (n = 1 3), pulmonary (n = 5) or bilateral (n = 3) outflow tract obstruction d ue to accessory atrioventricular valvar tissue and/or anomalous attach ments of the subvalvar apparatus. Primary diagnoses were isolated obst ruction of the systemic outflow tract or aortic arch (n = 7), transpos ition complexes (n = 6), previously repaired atrioventricular septal d efect (n = 3), functionally single ventricle (n = 3) and ventricular s eptal defect with pulmonary outflow obstruction (n = 2). Outflow tract gradients ranged from 20-110 mm Hg (median 58 mm Hg). Results. Comple te relief of obstruction due to atrioventricular valvar anomalies was possible in 14 patients. In six patients, the planned procedure either had to be modified or only partial relief of the obstruction was achi eved. In the remaining patient, who had borderline functionally single ventricle heart disease (unbalanced atrioventricular septal defect) a nd systemic outflow obstruction due to accessory and functional valvar apparatus, support was withdrawn because the parents refused univentr icular palliation and the valvar anomalies precluded a Ross-Konno proc edure. There were two early deaths. At follow-up ranging from 1 to 66 months (median 27 months), there was one death, and there has been no recurrence of outflow tract obstruction or residual atrioventricular v alvar tissue. Conclusions. Outflow tract obstruction caused by accesso ry of anomalous atrioventricular valvar structures is an uncommon and heterogeneous group of conditions that can have significant surgical i mplications. In the majority of cases, tailoring of surgical technique s will permit complete relief of obstruction. However, such anomalies may limit standard surgical options and necessitate an innovative appr oach in some patients. (J Am Coil Cardiol 1998;32:1741-8) (C) 1998 by the American College of Cardiology.