Combined Transaortic and Transapical Approach to Septal Myectomy for Complex Long-Segment Hypertrophy

Introduction

Complex long-segment septal hypertrophy consists of both hypertrophic subaortic stenosis and midventricular obstruction [1-3]. Untreated midventricular obstruction leads to recurrent symptoms and reduced survival [1, 2]. A combined transaortic and transapical approach during a single operation allows for excellent exposure of the midventricular obstruction-related hypertrophied septum [1, 2]. The authors demonstrate a combined transaortic and transapical approach to septal myectomy for complex long-segment hypertrophy.

Patient Presentation

A 48-year-old woman presented with extreme shortness of breath that worsened on exertion. Transesophageal echocardiogram demonstrated marked concentric left ventricular hypertrophy and a resting left ventricular outflow tract gradient over 60 mm Hg. Systolic anterior motion of the mitral valve was absent. Cardiac magnetic resonance angiography showed papillary muscle hypertrophy and a left ventricular wall thickness of 2.8 cm.

Surgical Technique

Step 1: Transverse Aortotomy
A transverse aortotomy was performed 1 cm above the sinotubular junction. The aortic valve leaflets were retracted. An Estech® retractor was used to expose the subaortic septum and left ventricular outflow tract.

Step 2: Transaortic Myectomy
The location of the mitral leaflet-septal contact was identified by the white fibrous endocardial scar. The hypertrophied septum to the right of the nadir of the right aortic cusp was sharply excised. The myectomy needed to extend at least 1 cm below the mitral leaflet-septal contact and was 1 cm deep. The 1 cm width of a No. 10 scalpel was used to assess the correct depth. The incision was extended leftwards to the anterior leaflet of the mitral valve and subsequently deepened and lengthened toward the apex of the heart.

Step 3: Transapical Myectomy
A 5 cm apical ventriculotomy was performed parallel and 2 cm lateral to the left anterior descending artery. The papillary muscles and chordae were retracted away from the septum. The distal extent of the transaortic resection was identified and the remaining hypertrophied septum was sharply excised. The enlarged papillary muscles were shaved to further increase the left ventricle cavity size.

Step 4: Closure of the Ventriculotomy
The ventriculotomy was closed in two layers with 3-0 polypropylene sutures in a continuous fashion using reinforcing Teflon strips.

Step 5: Closure of the Aortotomy
The aortotomy was closed in two layers with 4-0 polypropylene sutures in a continuous fashion.

Outcome and Discussion

Postoperative transesophageal echocardiography demonstrated a significantly enlarged left ventricle cavity with a peak gradient of 16 mm Hg. At six postoperative months, transthoracic echocardiography revealed a markedly dilated cavity and resolution of the intracavitary gradient. A combined approach prevents recurrence of elevated gradients and worsening symptoms from untreated midventricular obstruction [1, 2]. The Mayo Clinic has accumulated the largest series of patients with complex long-segment septal hypertrophy undergoing a combined approach. Their results are excellent, with low postoperative left ventricular outflow tract and midventricular gradients, low complication rates, short cross-clamp and perfusion times, and favorable short-term survival [1].

References

1. Hang D, Schaff HV, Ommen SR, Dearani JA, Nishimura RA. Combined transaortic and transapical approach to septal myectomy in patients with complex hypertrophic cardiomyopathy. J Thorac Cardiovasc Surg. 2018;155(5):2096-2102.
2. Kunkala MR, Schaff HV, Nishimura RA, et al. Transapical approach to myectomy for midventricular obstruction in hypertrophic cardiomyopathy. Ann Thorac Surg. 2013;96(2):564-570.
3. Said SM, Schaff HV. Surgical treatment of hypertrophic cardiomyopathy. Semin Thorac Cardiovasc Surg. 2013;25(4):300-309.