DEVELOPMENT OF A DOUBLE-CHAMBERED RIGHT VENTRICLE AFTER REPAIR OF TETRALOGY OF FALLOT

Objectives. We sought to determine the frequency, etiology and progres sive nature of midcavity obstruction in patients after primary repair of tetralogy of Fallot (TOF). Background. Midcavity obstruction (doubl e chambered right ventricle [DCRV]) represents a significant portion o f reoperations in patients who have had TOF repair. This group is stil l poorly defined. Methods. A retrospective review of clinical, echocar diographic and catheterization data for all patients with TOF who late r underwent reoperation for DCRV was performed. Results. Between 1973 and 1995, 552 children <2 years of age underwent primary TOF repair (m edian age 6.7 months). Long-term follow-up (median 50 months) was avai lable in 308 children. Of these, 17 children subsequently developed DC RV requiring reoperation. The median age at initial operation was 7.9 months. During a median follow-up interval of 43.2 months, murmur inte nsity increased in all patients, and the average subpulmonary gradient at catheterization increased from 24 +/- 10 to 80 +/- 27 mm Hg in sev en children (p = 0.002) and at Doppler echocardiography from 14 +/- 16 to 89 +/- 18 mm Hg in five children (p = 0.002), Before reoperation, 6 of the 17 children were symptomatic, During the operation (median ag e 55.4 months), obstruction was relieved by incision of hypertrophied anomalous muscle bundles in all 17 patients, with prominent fibrosis n oted in 8 patients. Excessive septal and parietal hypertrophy was note d in one child. No new transannular patches were required. Recurrent o bstruction has reappeared in 3 of these 17 children during follow-up. Conclusions. DCRV is a medium term complication of TOF repair in infan ts, with a minimal incidence of 3.1% (95% CI 1.8% to 4.9%). The condit ion is progressive and is due to anomalous muscle bundle hypertrophy o r fibrosis, or both, which may represent displaced insertion of a mode rator band, Further reobstruction does occur; continued careful follow -up is therefore essential. (C)1998 by the American College of Cardiol ogy.