SERIAL ECHOCARDIOGRAPHY FOR DECISION-MAKING IN RAPID 2-STAGE ARTERIALSWITCH OPERATION

Background. Rapid two-stage arterial switch operation is advocated in infants with simple transposition presenting late. Accurate assessment of left ventricular preparation is crucial to successful outcome. The role of echocardiography alone in surgical decision making remains un clear. Methods. Seventeen patients with simple transposition (mean age , 4 months) underwent pulmonary artery banding and modified Blalock-Ta ussig shunt (first stage) to prepare the left ventricle for the arteri al switch operation (second stage). Serial echocardiography was perfor med in the interval phase to assess left ventricular growth. Sixteen p atients underwent arterial switch operation after a mean interval of 1 0.4 +/- 4 days, with 14 successful conversions. There was one mortalit y (5.9%) and two conversions to a Senning repair. Results. In all pati ents a mean increase in left venhicular mass (40.8 +/- 17.8 g/m(2) to 81.4 +/- 25.4 g/m(2)) and posterior wall thickness (3.37 +/- 0.47 mm t o 4.63 +/- 0.58 mm) was recorded. Left ventricular end-diastolic inter nal diameter increased in all except the two switch failures. In all t he successful cases the left ventricle had assumed a circular shape on cross-section with the interventricular septum contracting in synergy with the left ventricular mass. In the two failures, however, the int erventricular septum had remained flat. Conclusions. Echocardiography can be used reliably in surgical decision making in rapid two-stage ar terial switch operation. Increase in left ventricular mass, left ventr icular posterior wall thickness, and left ventricular end-diastolic in ternal diameter toward normal combined with an acquisition of circular left ventricular configuration with the interventricular septum contr acting in synergy with the left ventricular mass appear to best predic t successful outcome.