Ann Thorac Surg 2004;78:355-357
© 2004 The Society of Thoracic Surgeons
How to do it
Septal myectomy with loop electrosurgical electrode for hypertrophic obstructive cardiomyopathy
Jen-Ping Chang, MD*a,
Chiung-Lun Kao, MDa,
Cheng-I Cheng, MDa,
Yuan-Kai Hsieh, MDa
a Division of Thoracic and Cardiovascular Surgery, Cardiology, Chang Gung Memorial Hospital at Kaohsiung, Taiwan, People's Republic of China
Accepted for publication April 18, 2003.
* Address reprint requests to Dr Chang, Division of Thoracic and Cardiovascular Surgery, Chang Gung Memorial Hospital at Kaohsiung, 123 Ta-Pei Rd, Niao Sung Hsiang, Kaohsiung Hsien, Taiwan, People's Republic of China
e-mail: c9112772{at}adm.cgmh.org.tw
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Abstract
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Excellent results have been described for surgical relief of left ventricular outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy. Transaortic septal myectomy is technically demanding, especially when the lesion extends deep to the midcavity of left ventricle. A loop electrosurgical electrode is used to satisfactorily circumvent this problem.
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Introduction
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hypertrophic obstructive cardiomyopathy, septal myectomy, loop electrosurgical electrode he most effective treatment for symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM) is still disputed. The long-term results of various treatment options are not well defined. Although transaortic septal myectomy is fairly demanding because of limited exposure, excellent immediate and long-term results have been described [1–4]. The hypertrophic left ventricular outflow tract (LVOT) is usually excised with a knife [5, 6]. However, some difficulties exist when the procedure needs to be accomplished down to the midcavity level. We advocate a modified technique by using a 3/8-inch CONMED loop electrosurgical electrode (NY, USA 13501) to perform this procedure more effectively and easily.
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Technique
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The operation is performed via lower half ministernotomy with standard cardiopulmonary bypass and cold oxygenated crystalloid cardioplegic arrest. On inspection through the oblique aortotomy, the pathology of the aortic valve is confirmed. Two small, flat-bladed leaflet retractors are used to displace the right and left aortic leaflets toward the aortic wall and out of the way. A 3/8-inch loop electrosurgical electrode with a long handle (Fig 1)
is connected to the usual type of cautery device with the electrical setting of 50 W, pure cutting mode. The loop electrode is then introduced deeply into the ventricular cavity and embedded into the farthest portion of the septal bulge, between the right coronary ostium and the right and left coronary commissure, under switch-off mode. This maneuver facilitates avoidance of accidental injury to the mitral apparatus. When drawn forward with switch-on mode, a 3-mm wide, 4-mm thick septal muscle fragment can be excised in liberal length without counteraction (Fig 2). The electrically excised fragments will be attached to the loop electrode and can be easily removed; hence, dislodgement of the resected muscle leading to embolization will not be a problem.
From the preoperative transthoracic echocardiogram, we know the septum is 2 to 2.5 cm thick (Fig 3).
We can then resect 1 cm to 1.5 cm deep without concern of causing a ventricular septal defect [6]. Usually 3 to 4 passes (1.2- to 1.6-cm depth) for a track of the surgical loop are required to achieve an adequate resection. The myectomy trough is carried within the left ventricular cavity 3 mm below the aortic annulus and extended to the base of papillary muscles in repeated manner without any difficulty because the muscle tissue does not tend to shred and the smooth surface is maintained. After completion of concomitant procedures as necessary, cardiopulmonary bypass is discontinued, and the gradient across the LVOT is measured directly.
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Fig 3. Parasternal long-axis echocardiogram shows the severe obstructive septal hypertrophy with 2.5-cm in thickness (arrows).
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Results
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This technique was applied in 2 female patients (77 and 67 years old respectively) with HOCM with significant pressure gradient across the LVOT of 55 and 65 mm Hg respectively (Figure 3). Simultaneous aortic valve replacement (for calcified tricuspid aortic valve) with 21-mm porcine bioprosthesis was done in one patient. Aortic (dilated sinotubular junction), mitral (annular dilation and posterior leaflet tethering), and tricuspid (annular dilation) valve repairs were concomitantly performed in another patient.
Both patients recovered uneventfully and discharged with 6 weeks of oral anticoagulation (warfarin) only. In a mean follow-up of 12 months (11 and 13 months), serial echocardiography in both patients revealed well-functioning valves without pressure gradient across the LVOT (Fig 4).
Both patients have discontinued warfarin.
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Fig 4. Postoperative parasternal long-axis echocardiogram shows widely patent left ventricular outflow tract (diameter 2.15 cm) without pressure gradient.
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Comment
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Several treatment options are available for patients with medical refractory symptomatic HOCM, including dual chamber pacing, percutaneous transluminal septal myocardial ablation, mitral valve replacement, and surgical transaortic septal myomyectomy. Excellent results have been reported for transaortic subvalvular myomyectomy [1–4]; hence, this has become the procedure of choice for patients whose symptoms are refractory to medical treatment or for patients who require concomitant intracardiac procedures.
Transaortic septal myectomy seems easy in concept, but the actual resection of muscle is sometimes difficult, especially when the diseased septum extends to the midcavity of left ventricle. Morrow has advocated the myectomy using three big incisions [5]. Merrill and associates have used fairly liberal scissor dissection to add to the original resection technique [4]. Mavroudis has recommended skin hooks to retract the muscle and hold it in tension while performing myectomy [4]. Sherrid and associates have also described a similar technique in detail [6]. These reports regarding technical modification support the concept that transaortic septal myectomy is indeed fairly demanding.
In fact, our technical modification using loop electrosurgical electrode has made this valuable but technically demanding procedure particularly easy. An extensive myectomy trough can be carried in pieces deep into the left ventricular midcavity with this 3/8-inch loop electrosurgical electrode without any difficulty. Unfavorable damage to the subvalvular apparatus is no longer a problem. Consequently, a complete septal myectomy is fairly straightforward. Our limited experiences in this modified procedure confirm that transaortic septal myectomy can be undergone by loop electrode excision method with low risk and fewer demands. This is true even when myectomy is accompanied by additional cardiac procedures.
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References
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- ten Berg J.M., Suttorp M.J., Knaepen P.J., Ernst S.M., Vermeulen F.E., Jaarsma W. Hypertrophic obstructive cardiomyopathy. Initial results and long-term follow-up after Morrow septal myectomy. Circulation 1994;90:1781-1785.[Abstract/Free Full Text]
- Heric B., Lytle B.W., Miller D.P., Rosenkranz E.R., Lever H.M., Cosgrove D.M. Surgical management of hypertrophic obstructive cardiomyopathy: early and late results. J Thorac Cardiovasc Surg 1995;110:195-208.[Abstract/Free Full Text]
- Robbins R.C., Stinson E.B. 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]
- Merrill W.H., Friesinger G.C., Graham T.P., Jr, et al. Long-lasting improvement after septal myectomy for hypertrophic obstructive cardiomyopathy. Ann Thorac Surg 2000;69:1732-1735.[Abstract/Free Full Text]
- Morrow A.G. Hypertrophic subaortic stenosis. Operative methods utilized to relieve left ventricular outflow obstruction. J Thorac Cardiovasc Surg 1978;76:423-430.[Abstract]
- Sherrid M.V., Chaudhry F.A., Swistel D.G. Obstructive hypertrophic cardiomyopathy: echocardiography, pathophysiology, and the continuing evolution of surgery for obstruction. Ann Thorac Surg 2003;75:620-632.[Abstract/Free Full Text]
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Abstract
Introduction
