Pathological changes of the myocardium in patients after atrial repair for transposition of the great arteries: a possible explanation for left ventricular dysfunction after secondary arterial switch.
BACKGROUND
Patients with transposition of the great arteries who underwent an atrial repair in infancy are likely to develop right ventricular dysfunction later in life. For these patients a two-stage arterial switch operation has been advocated by some groups but mortality even from the initial pulmonary banding procedure for retraining the left ventricle has been reported to be considerable. We asked whether pathological alterations of the left ventricular myocardium could explain for the failure of the left ventricle observed in patients after two-stage arterial switch operations.


METHODS
Twelve patients aged 16.9 [8-25.4] years (median [range]) with transposition of the great arteries after atrial repair in infancy were enrolled. Median follow-up interval was 15.8 [7.8-22.1] years. Measurements of right and left ventricular systolic function were performed by echocardiography. In addition all patients underwent cardiac catheterization. Endomyocardial biopsies were taken from the right and left ventricle and examined histopathologically.


RESULTS
Two out of twelve patients showed mildly reduced systolic right ventricular function. Systolic function of the left ventricle was normal in all patients on echocardiography but six out of twelve patients showed clusters of fibrous and fatty degeneration on biopsy specimens obtained from the left ventricle.


CONCLUSIONS
We conclude that degenerative left ventricular myocardial changes could serve as an explanation for left ventricular failing when retraining the left ventricle during two-stage arterial switch operations.
D000293:Adolescent; D000328:Adult; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000601:surgery*; D006801:Humans; D008297:Male; D017682:Myocardial Stunning / Q000209:etiology* / Q000473:pathology*; D009206:Myocardium / Q000473:pathology; D014188:Transposition of Great Vessels / Q000150:complications / Q000473:pathology / Q000601:surgery*; D017211:Treatment Failure; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000473:pathology*