Prolonged cardiac recovery from exercise in asymptomatic adults late afteratrial correction of transposition of the great arteries: Evaluation with magnetic resonance flow mapping

After atrial correction of transposition of the great arteries (TGA), dysfu nction of the systemic right ventricle at rest and during exercise has been reported. Information on changes in systemic right ventricular function du ring recovery from exercise is lacking. This study evaluates cardiac recove ry from supine exercise using magnetic resonance (MR) imaging in patients w ith asymptomatic TGA after atrial correction. Flow in the ascending aorta, representing stroke volume of the systemic ventricle, was assessed with MR flow mapping in 10 asymptomatic patients with atrially corrected TGA and in 12 controls at rest during exercise and an 8-minute recovery period. In re sponse to exercise, the patients had a smaller increase in heart rate, stro ke volume, and cardiac output than did controls. After exercise, no signifi cant difference in halftime of heart rate recovery was observed (patients, 48 +/- 7 seconds; controls, 39 +/- 4 seconds [p >0.05]). In the patients, t he time course of stroke volume recovery was significantly different (p <0. 001). Stroke volume in the patients, as a percent difference from rest, rem ained significantly elevated, from 2.5 minutes (+ 16 +/- 5% vs + 7 +/- 6%; p < 0.05) to 8 minutes (+4 +/- 7% vs -3 +/- 5%; p <0.05) after exercise. Su bsequently, cardiac output remained significantly elevated, from 4.5 minute s (+27 +/- 13% vs +15 +/- 11%; p <0.05) to 7 minutes (+22 +/- 11% vs +12 +/ - 12%; p <0.05) after exercise. We conclude that heart rate recovery is wit hin normal limits in patients with atrially corrected TGA. Furthermore, car diac recovery from exercise, assessed with MR flow mapping, is prolonged in patients with asymptomatic TGA after atrial correction. Abnormal recovery may reflect dysfunction of the systemic right ventricle and an altered meta bolic response to exercise. (C)2001 by Excerpta Medica, Inc.