Author + information
- Received December 11, 1991
- Revision received December 26, 1991
- Accepted January 8, 1992
- Published online July 1, 1992.
- Leeanne E. Grigg, MBBS1,
- E.Douglas Wigle, MD, FACC,
- William G. Williams, MD,
- Lorretta B. Daniel, MD and
- Harry Rakowski, MD∗
- ↵∗Address for correspondence: Harry Rakowski, MD, EN 12-212, Toronto General Hospital, 200 Elizabeth Street, Toronto, Ontario, Canada M5G 2C4.
To better understand the pathophysiology of obstruction of left ventricular outflow in hypertrophic cardiomyopathy and to determine the value of intraoperative transesophageal Doppler echocardiography in decision making, 32 consecutive patients undergoing ventriculomyectomy were assessed. The mean preoperative left ventricular outflow gradient was 83 ± 39 mm Hg and the mean basal septal width was 24 ± 6 mm. Compared with transesophageal findings in 10 normal control subjects, the mitral leaflets were longer and the coaptation point was abnormal in the patients with obstructive hypertrophic cardiomyopathy (anterior and posterior leaflet lengths in the patients were 31 ± 4 vs. 22 ± 3 mm in the control group [p < 0.00001] and 20 ± 2 vs. 15 ± 3 mm in the control group [p < 0.00001]). The coaptation point in the patient group was in the body of the leaflets at a mean of 9 ± 2 mm from the anterior leaflet tip, whereas it was at or within 3 mm of the leaflet tip in the normal group.
During early systole, the distal third to half of the anterior mitral leaflet angled sharply anteriorly and superiorly (systolic anterior motion), resulting in leaflet-septal contact and incomplete mitral leaflet coaptation in mid-systole. This caused the formation of a funnel, composed of the distal parts of both leaflets, that allowed a jet of posteriorly directed mitral regurgitation to occur in mid- and late systole. The sequence of events in systole was eject/obstruct/leak.
Transesophageal echocardiography was also helpful in planning the extent of the resection, assessing the immediate result and excluding important complications. In successful cases, the post-myectomy study showed 1) a dramatic thinning of the septum, with widening of the left ventricular outflow tract to a width similar to that in the normal subjects, 2) resolution of systolic anterior motion and the left ventricular outflow tract color mosaic, and marked reduction or abolition of mitral regurgitation despite persistence of abnormal mitral leaflet length and an abnormal mitral leaflet coaptation point. The routine use of transesophageal echocardiography in patients undergoing surgical myectomy for the treatment of obstructive hypertrophic cardiomyopathy is recommended.
↵1 Dr. Grigg was supported in part by the Beecham Travelling Scholarship from the Royal Australian College of Physicians, Sydney, Australia.
☆ This study was supported in part by the Heart and Stroke Foundation of Ontario, Toronto.
- Received December 11, 1991.
- Revision received December 26, 1991.
- Accepted January 8, 1992.