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Published on: September 25, 2009
Outflow obstruction after the arterial switch operation: a multiinstitutional study. Congenital Heart Surgeons
W G Williams1, J M Quaegebeur, J W Kirklin
1Department of Cardiovascular Surgery, Hospital for Sick Children, Toronto, Ontario, Canada.
Objective:
Our objectives were to discover whether outflow obstruction immutably accompanies the arterial switch operation and to identify factors that may decrease its prevalence.
Methods:
Percutaneous or surgical reintervention for obstruction after an arterial switch was selected as an end point for obstruction. Its risk factors were identified by time-related multivariable analyses of yearly follow-up data from 514 neonates with simple transposition or transposition with ventricular septal defect entering 23 institutions before 15 days of age between January 1, 1985, and March 1, 1989.
Results:
Sixty-two patients underwent 86 reinterventions for right-sided obstruction (83% free at 10 years) and six for left-sided obstruction (98% free at 10 years). After 2 years, right-sided obstruction occurred at a rate of about 1% per year and left-sided at a rate of about 0.1% per year. Right ventricular infundibular or valvular obstruction was associated with the aorta and pulmonary trunk positioned side-by-side, coexisting coarctation, use of prosthetic material in sinus reconstruction, one institution, and earlier institutional experience. Pulmonary trunk or pulmonary artery obstruction was associated with lower birth weight, left coronary artery arising from sinus 2, coronary explantation away from the transection site, three institutions, and earlier institutional experience.
Conclusions:
A risk-adjusted base incidence (0.5% per year) of reintervention for right-sided obstruction continues late after operation. It is due in part to congenital variability or abnormality of right ventricular outflow structures and to experience and surgeon variability resulting in suboptimal pulmonary trunk reconstruction. The same sources of variability probably affect the aortic root, but its native characteristics plus higher distending pressure make the base incidence considerably less (0.1% per year).
