712-4 Role of Intraoperative Transesophageal Echocardiography in Patients with Hypertrophic Obstructive Cardiomyopathy

To evaluate the role of intraoperative TEE (IOTEE) in hypertrophic obstructive cardiomyopathy (HOCM), IOTEE in 74 patients with HOCM who underwent myectomy from 1988 to 1993 were reviewed. There were 38 men and 36 women with a mean age of 45±22 years (range: 2–82). All had preoperative transthoracic echo showing dynamic LVOT obstruction with a mean peak gradient of 73±37mmHg and a basal septal thickness of 25±9mm at baseline. Prior to cardiopulmonary bypass, IOTEE discovered unsuspected morphologic abnormalities in 9 (12%): subaortic membrane 1, flail mitral valve 1, tricuspid valve fibroelastoma 1, mitral valve prolapse 4, patent foramen ovale 1, and bicuspid aortic valve 1. Additional surgical procedure was performed in each of the first 3 patients (4%). Postoperatively, IOTEE detected severe residual mitral regurgitation (MR) with marked systolic anterior motion (SAM) of the mitral valve in 3, ventricular septal defect in 1 patient, all of which (5%) were surgically corrected with a second pump run. All 3 cases of severe residual MR due to inadequate myectomy occurred during early surgical experience (1988 and 1989). Other 5 (7%) non-surgical postoperative findings included severe MR associated with poor LV function in 1, low ejection fraction in 2, hypovolemia with hypotension in 1 and regional wall motion abnormality in 1 patient. The mitral valve was structurally normal in 61 pts (82%), 3 (4%) had flail PMVL, 4 (5%) had PMVL prolapse, 1 had AMVL prolapse, 1 had bileaflet prolapse, 1 had valvular calcification and 4 had mitral annular calcification. SAM was present in 69 (93%) prebypass and was still present in 45 (61%) immediate postbypass and was present in 30 (41%) predischarge. The grade of MR decreased from 2.3±1.0 prebypass to 1.1±0.5 postbypass (p<0.0001). Absence of post-bypass SAM was associated with significant postoperative reduction of MR evaluated by IOTEE (p=0.024).ConclusionIn patients with HOCM undergoing myectomy, IOTEE is valuable in detecting preoperatively unknown cardiac pathologies in 12%, altering surgical procedure in 4%, and in assessing the result of myectomy, requiring a second pump run in 5%. IOTEE was also valuable in identifying the etiology of postoperative LV dysfunction in 7% and intrinsic structural abnormality of mitral valve in 19%. Residual SAM detected by IOTEE after septal myectomy resolves in 33% of Pts by the time of predischarge transthoracic echo study