Left Ventricular Outflow Tract Obstruction in Complete Transposition of the Great Arteries

– Echocardiography Criteria for Surgical Strategies –

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Background: The arterial switch operation (ASO) may be infeasible in patients with transposition of the great arteries (TGA) and left ventricular outflow tract obstruction (LVOTO). Methods and Results: Patients with LVOTO were identified among the 229 patients with TGA repaired between 1991 and 2006. Dynamic LVOTO was defined as LVOTO without LVOT abnormalities requiring resection (group I, receiving ASO). Fixed LVOTO was defined as LVOTO with LVOT abnormalities that could (group IIa, receiving ASO) or could not be resected (group IIb, receiving operations other than ASO). Preoperative echocardiography parameters were compared to identify criteria predicting the surgical findings of LVOTO. LVOTO was found in 63 patients (27.5%): 39 with dynamic and 24 with fixed (14 group IIa and 10 IIb) LVOTO. Late, severe neo-aortic regurgitation occurred more frequently in group IIa patients. Echocardiography evidence of isolated subvalvular stenosis, pulmonary to aortic valvular annulus ratio >0.98 or LVOT pressure gradient <22 mmHg predicted dynamic LVOTO (sensitivity 86.3%, specificity 94.7%), whereas that of an annulus ratio <0.85 and a pressure gradient >35 mmHg predicted fixed and non-resectable LVOTO (sensitivity 100%, specificity 100%). Conclusions: Approximately one-fourth of TGA patients had LVOTO. Echocardiography criteria identified those with dynamic or fixed but resectable (ASO) LVOTO with satisfactory sensitivity and specificity.  (Circ J 2010; 74: 1214 - 1218)