Intraoperative transgastric echo assessment during left ventricular outflow tract surgery: A reliable predictor of residual obstruction

Standard transesophageal echocardiography (TEE) views of the left ventricular outflow tract (LVOT) are limited by poor Doppler beam alignment with the peak velocity of flow. Transgastric imaging allows well-aligned continuous-wave Doppler interrogation of the LVOT and was attempted during intraoperative TEE in all children undergoing LVOT surgery at Children's Hospital of Wisconsin. Thirty-eight patients, ranging in age from 2 days to 18 years (median, 5.2 years) and in weight from 2.9 to 100 kg (median, 16.7 kg), had TEE during surgery to resect membranous or fibromuscular subaortic obstruction (20 patients), valvuloplasty for aortic stenosis/insufficiency (13 patients), aortoplasty for supravalvar stenosis (one patient), or repair/replacement for aortic insufficiency (four patients). In four patients, transgastric images of the LVOT could not be obtained. Intraoperative Doppler gradients identified severe residual obstruction (mean, 67 ± 13.5 mmHg) after surgery in seven patients; six of these patients underwent immediate repeat operation with subsequent adequate relief, and one patient required later aortoventriculoplasty for persistent annular/valvar obstruction. All other patients had successful LVOT reconstruction with intraoperative Doppler gradients ranging from 0 to 46 mmHg, and none required early repeat operation. Good correlation was found between the intraoperative transgastric gradient (mean, 25.8 ± 17.7 mmHg) and the early postoperative transthoracic echo gradient (mean, 21.8 ± 21.4 mmHg). In addition, there was consistent agreement in the assessment of aortic insufficiency between the transesophageal and transthoracic studies. We conclude that transgastric Doppler assessment of the LVOT is a critical component of intraoperative monitoring during LVOT surgery and is a reliable predictor of residual obstruction.