Interactive Cardiovascular and Thoracic Surgery 2:650-652(2003)
© 2003 European Association of Cardio-Thoracic Surgery
Brief communication - Congenital |
Modified septal myectomy for small patients with hypertrophic obstructive cardiomyopathy
Tetsuya Ueno*,
Kazuyuki Ikeda and
Yasuo Koga
Division of Cardiovascular Surgery, Ureshino National Hospital, 2436 Ureshino-machi, Fujitsu-gun, Saga 843-0393, Japan
* Corresponding author. Tel.: +81-954-43-1120; fax: +81-954-42-2452
tueno{at}uresino.hosp.go.jp
Received May 26, 2003;
received in revised form July 28, 2003;
accepted July 30, 2003
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Abstract
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For successful myectomy for hypertrophic obstructive cardiomyopathy, it is essential that a sufficient amount of muscle be excised under adequate surgical exposure. In addition to the method of standard transaortic myectomy, supplemental use of a flexible endoscope and a hand-made blade knife, which are available in any institution, can provide successful myectomy, especially for small patients, easily and safely.
Key Words: Myectomy; Small patients; Hypertrophic obstructive cardiomyopathy
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1. Introduction
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Septal myectomy is the treatment of choice for patients with hypertrophic obstructive cardiomyopathy (HOCM), who have severe, medication-refractory symptoms. However, because of limited operative exposure, a number of operative experiences may be required for successful septal myectomy. We report a modified method of transaortic myectomy with combined use of a hand-made blade knife and a flexible fiberscope for surgeons who are unfamiliar with this operation.
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2. Technique
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A 69-year-old woman, 137 cm and 37 kg, had sudden chest oppression and palpitation despite full medications for HOCM. Echocardiography and left heart catheter study showed remarkable septal hypertrophy (maximal width 27 mm) at the LV outflow tract (OT), associated with an aortic-left ventricular pressure gradient (Ao-LV PG) more than 100 mmHg and grade III mitral regurgitation (MR). Systolic anterior movement (SAM) of the anterior mitral leaflet caused mal-coaptation and regurgitant flow towards the posterior wall of the left atrium.
A flexible fiberscope, which was usually used as an intra-operative cholangioscopy sterilized by ethylene oxide, disclosed the extension of hypertrophic septum to be resected and its anatomic relationship to the subvalvular mitral apparatus (Fig. 1a). The transitional point between the hypertrophied septum to be resected and the septum not to be, could be confirmed by a change in colour of the endothelium from white to red. As proposed by Schoendule and colleagues [1], a sharp double hook retractor was hanged at that point and lifted upward for a better exposure of the hypertrophic septum. A No. 15 blade knife was held in the middle of a mosquito forceps so as to stand perpendicularly to it, leaving 10 mm of cutting edge protruding from the mosquito forceps (Fig. 2). This device was then advanced into the LV and pushed into the hypertrophied septum so as to make the blade insert into the septum vertically. The mosquito forceps was slid straight downward towards the lowest point of the hypertrophied septum (Fig. 2). This technique provided secure myotomy with depth no greater than 10 mm. Two parallel myotomies were made on the septum as suggested by Morrow [2]. The myocardium between the two myotomy lines was resected by fine scissors. After the resection was completed, the fiberscope was inserted into the LV. Because some amount of hypertrophic myocardium had been left behind (Fig. 1b), this was excised by fine scissors. The patient had an uneventful intra- and postoperative course with reduction of Ao-LV PG less than 15 mmHg and disappearance of MR.
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Fig. 1 Fiberscopic observation. A fiberscope showed the anatomical relationship between hypertrophied ventricular septum and subvalvular mitral apparatus (a). After the initial myectomy, there still remained some amount of hypertrophic myocardiaum to be resected in the ventricular septum (b). S, ventricular septum; and AML, anterior mitral leaflet.
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Fig. 2 Myotomy by hand-made knife. The blade on the forceps was inserted vertically into the hypertrophied septum and slid straight down towards the bottom level of the myectomy. S, ventricular septum; L, left aortic leaflet; R, right aortic leaflet; and AML, anterior mitral leaflet.
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Another patient with HOCM was a 68-year-old woman, 151 cm and 48 kg, who suffered exertional dyspnea and repeated syncope. She had an Ao-LV PG of 160 mmHg, associated with grade III MR. The maximal width of the septum at the LVOT was 34 mm. She underwent a similar septal myectomy. Postoperative Ao-LV PG was almost zero and MR was reduced to grade I.
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3. Comment
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Mitral regurgitation associated with HOCM has been shown to be related to SAM arising from the Venturi effect or drag forces, in most cases [3]. It is well known that septal myectomy alone leads to marked reduction of MR through improvement of SAM [4]. However, outside of a limited number of institutions with a large volume of operative experience with HOCM, septal myectomy is technically demanding.
The transaortic septal myectomy described by Morrow [2] has been frequently selected as the operation of choice for HOCM. However, the extension of hypertrophied septum or its anatomical relationship to subvalvular apparatus such as papillary muscles and chordae is not easily observed, especially in small patients like ours, through the aortic valve and narrowed LVOT. Under a poor surgical view, accidental septal perforation or injury to subvalvular apparatus may occur. Insufficient resection of myocardium can also make weaning from cardio-pulmonary bypass difficult and trigger a stormy postoperative course.
A flexible fiberscope can reveal the in situ configuration of the LV lumen and provide detailed anatomical information within the LV, including the extent of hypertrophied septum, the relationship between hypertrophied septum and subvalvular apparatus, and the lowest level of myectomy at which a sharp double hook retractor should be hanged in order to pull up the septum. The fiberscope is also helpful for observing whether an acceptable amount of myocardium has been excised, after the first resection; in the event that some amount of hypertrophied myocardium is left behind, an additional resection is required, as was done in our first case.
Another technical problem is controlling the depth of the myectomy. Morrow advised that the depth be changed in accordance with the width of hypertrophied septum [2]. We created a 10 mm of blade depth by using the mosquito forceps as a guard because a 10-mm myotomy depth was regarded as acceptable in our cases. However, we can change the length to which a No. 15 blade knife protrudes from the forceps, obtaining our desired depth of myotomy with ease. With this hand-made blade knife, accidental septal perforation or insufficient myectomy can be avoided and uniform depth during myotomy be maintained.
Combined use of a flexible fiberscope and a hand-made blade knife can assist inexperienced surgeons in performing successful myectomy, especially for the small patients with HOCM easily and safely, from their first cases.
doi:10.1016/S1569-9293(03)00176-2
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References
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- Schoendule FA, Klues HG, Reith S, Messmer BJ. Surgical correction of hypertrophic obstructive cardiomyopathy with combined myectomy, mobilization and partial excision of the papillary muscles. Eur J Cardiothorac Surg. 1994;8:603–608[Abstract]
- Morrow AG. Hypertrophic subaortic stenosis. Operative methods utilized to relieve left ventricular outflow obstruction. J Thorac Cardiovasc Surg. 1978;76:423–430[Abstract]
- Sherrid MV, Chu CK, Delia E, Mogtader A, Dwyer EM Jr. An echocardiographic study of the fluid mechanics of obstruction in hypertrophic cardiomyopathy. J Am Coll Cardiol. 1993;22:816–825[Abstract]
- Robbins RC, Stinson EB. Long-term results of left ventricular myotomy and myectomy for obstructive hypertrophic cardiomyopathy. J Thorac Cardiovasc Surg. 1996;111:586–594[Abstract/Free Full Text]
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Abstract
1. Introduction