Quantitative Assessment of the Operative Results After Extended Myectomy and Surgical Reconstruction of the Subvalvular Mitral Apparatus in Hypertrophic Obstructive Cardiomyopathy Using Dynamic Three-Dimensional Transesophageal Echocardiography

Abstract

Objectives. The aim of this study was to examine the value of dynamic three-dimensional (3D) transesophageal echocardiography (TEE) for the postoperative evaluation after extended myectomy and surgical reconstruction of the subvalvular mitral valve apparatus in patients with hypertrophic obstructive cardiomyopathy (HOCM).Background. Two-dimensional imaging techniques such as echocardiography, computed tomography and magnetic resonance imaging have not been able to precisely quantify the effects of surgical therapy on the morphology of the left ventricular outflow tract (LVOT).Methods. Multiplane TEE with 3D reconstruction was performed in 11 patients before and after the operation and in 16 normal control subjects for comparison. The preoperative maximal systolic pressure gradient in the LVOT was 69 ± 59 mm Hg. The following variables were measured within the dynamic 3D data set: depth, width, length and cross-sectional area (CSA) gain caused by the myectomy trough, minimal CSA of the LVOT at each time point and its cyclic changes and maximal mitral leaflet deviation during systole.Results. Functional class improved from 3.0 ± 0.2 before the operation to 1.5 ± 0.6 after it. The maximal systolic pressure gradient in the outflow tract decreased to 26 ± 21 mm Hg postoperatively (p < 0.001). Minimal CSA of the outflow tract increased from 1.1 ± 1.2 to 3.8 ± 1.9 cm2postoperatively (p < 0.001), similar to the value of the control group (4.2 ± 1.5 cm2, p = NS). The area gain due to the myectomy trough was 1.3 ± 1.0 cm2, corresponding to 48 ± 12% of the total operative area difference. Maximal systolic depth of the myectomy was 7 ± 2 mm, maximal width was 20 ± 8 mm and length was 28 ± 7 mm. Maximal deviation of the mitral leaflets fell from 15 ± 7 to 6 ± 7 mm postoperatively (p < 0.01). In five patients mass measurements of the intracavitary portion of the papillary muscle (PM) revealed an increase from 7.3 ± 1.0 to 12.1 ± 2.5 g due to surgical mobilization of PMs (p < 0.01).Conclusions. 3D TEE quantifies the differences in outflow tract morphology before and after surgery for HOCM. This technique may have an impact on the planning of operative interventions and allow for the evaluation of its results.