Use of Intraoperative Dobutamine Stress Echocardiography on Outcomes of Septal Myectomy

Abstract

Septal myectomy is the standard treatment for obstructive hypertrophic cardiomyopathy. We studied the impact of intraoperative pre- and postprocedure dobutamine stress transesophageal echocardiography on surgical planning and outcomes of septal myectomy. We identified 55 patients undergoing septal myectomy over a 24-month period. All patients underwent resting and dobutamine stress (20-40 mcg/kg/min) echocardiography after induction of anesthesia pre- and postprocedure. Demographic, clinical, and imaging data were prospectively collected. Mean age was 59 (42-68). A total of 69% of patients were New York Heart Association Class III/IV. During outpatient evaluation, peak preoperative resting left ventricular outflow tract gradient was 91.6 mm Hg and 94% (50/53) had severe stress-induced mitral regurgitation (MR). After induction, peak resting gradient fell to 47.8 mm Hg and 43% (24/55) had improved gradients (<30 mm Hg). With stress, preprocedure left ventricular outflow gradient increased to 130 mm Hg and all occult gradients were unmasked. Postprocedure, peak resting and stress gradients were substantially reduced (10.2 ± 6.8 mm Hg and 23.6 ± 8.5 mm Hg, respectively). With stress, 84% (42/50) demonstrated reduction in severity of MR to none and/or mild with no patients having greater than moderate. Postprocedure stress echocardiography identified 3 patients with residual gradients, which led to return to bypass for additional procedures and resulted in resolution of elevated residual gradients. Postoperative 60-day stress echocardiography showed sustained resolution of gradients and MR. In this series, 43% of patients had occult left ventricular outflow gradients after induction of anesthesia. Intraoperative stress echocardiography during septal myectomy is useful to unmask occult gradients and confirm adequate myectomy. This imaging strategy is associated with reliable relief of obstruction and MR as demonstrated at 60-day follow-up.

Keywords: Hypertrophic obstructive cardiomyopathy; Left ventricular outflow obstruction; Septal myectomy; Transesophageal echocardiogram.