INTRAOPERATIVE TRANSGASTRIC ECHO ASSESSMENT DURING LEFT-VENTRICULAR OUTFLOW TRACT SURGERY - A RELIABLE PREDICTOR OF RESIDUAL OBSTRUCTION

Standard transesophageal echocardiography (TEE) views of the left vent ricular outflow tract (LVOT) are limited by poor Doppler beam alignmen t with the peak velocity of flow. Transgastric imaging allows well-ali gned continuous-wave Doppler interrogation of the LVOT and was attempt ed during intraoperative TEE in all children undergoing LVOT surgery a t 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 membr anous or fibromuscular subaortic obstruction (20 patients), valvulopla sty for aortic stenosis/insufficiency (13 patients), aortoplasty for s upravalvar stenosis (one patient), or repair/replacement for aortic in sufficiency (four patients). In four patients, transgastric images of the LVOT could not be obtained. Intraoperative Doppler gradients ident ified severe residual obstruction (mean, 67 +/- 13.5 mmHg) after surge ry in seven patients; six: of these patients underwent immediate repea t operation with subsequent adequate relief and one patient required l ater aortoventriculoplasty for persistent annular/valvar obstruction. All other patients had successful LVOT reconstruction with intraoperat ive Doppler gradients ranging from 0 to 46 mmHg, and none required ear ly repeat operation. Good correlation was found between the intraopera tive transgastric gradient (mean, 25.8 +/- 17.7 mmHg) and the early po stoperative 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. W e conclude that transgastric Doppler assessment of the LVOT is a criti cal component of intraoperative monitoring during LVOT surgery and is a reliable predictor of residual obstruction.