**5. Surgical septal myectomy**

Surgical septal myectomy is the therapeutic gold standard for the treatment of drug-refractory disabling symptoms in HCM caused by LVOT obstruction. This procedure can relieve hemodynamic disorders and has an acceptable surgical risk when performed on appropriate patients and in experienced centers [7].

It was performed, for the first time, in 1968 by Morrow et al. [8]; initially, the myectomy was limited in scope, but nowadays the resection is much more aggressive in terms of both width and length [5, 9]. Sparing the cardiac conduction system, septal myocardium is resected, depending on the area of hypertrophy and extending if necessary as far as the level of the papillary muscles, to an extent sufficient to eliminate the obstruction, retaining septal thickness of 1 cm. Surgical septal myectomy can be performed as follows:

#### **5.1 Transaortic extended septal myectomy (TAESM)**

TAESM through a transverse aortotomy, the aortic valve is totally exposed and the aortic leaflets are retracted so as to inspect the LVOT, the hypertrophic cardiac muscle and anterior MV leaflet. In order to open the LVOT and reduce the gradient to <30 mmHg, resection of the hypertrophic muscle until the thickness of the LV wall and interventricular septum became nearly normal by visual inspection, has to be performed. The myectomy should be initiated about 1.5 cm below the aortic annulus starting at the level of the non-coronary/right-coronary commissure to avoid the membranous septum and avoid creating a secondary ventricular septal defect (VSD). The septum is cut into as much as possible to relieve the obstruction and it is extended toward the left/non-coronary commissure so that the entire

**Figure 2.** *Extension of the resection under the membranous septum.*

septum is trimmed off all around (**Figure 2**). The TAESM is the most commonly used technique and it has been associated with very low mortality, consistent alleviation of outflow gradients and excellent long-term survival [10].

### **5.2 Transmitral septal myectomy (TMSM)**

The MV is approached through the left atrium, in the interatrial groove. Then, the base of the AL is widely detached from commissure to commissure, with the septum that lies just in front of the surgeon. The myectomy is continued further toward the apex with at least 1 cm depth of muscle removed. The anterior MV leaflet is then reconstructed (sometimes using an autologous pericardial patch with the size of the patch that should be as biggest as possible, in order to move posteriorly toward the left ventricle the coaptation plane). This approach is useful for those patients with diffuse hypertrophy extending to or below the papillary muscles with midcavity muscular obstruction: these patients are suboptimal candidates for the Morrow procedure. Benefits of the transmitral exposure include a wide view of the ventricular septum, absent risk of injury to the aortic valve cusps, and the opportunity to address concomitant abnormalities of the MV and subvalvular apparatus.

#### **5.3 Complete septal myectomy by a double approach (aortic and mitral)**

In patients with simultaneous MR due to SAM, the insufficiency is almost always reduced or eliminated by myectomy alone. Sometimes, there may be associated a lesion of the aortic valve and/or fibrous subaortic stenosis; these also require surgical correction, depending on their severity. Intraoperative echocardiography helps the surgeon to determine the individual extent of the disease and decide on the necessary scope of resection.

**111**

*Surgical Treatment of Hypertrophic Obstructive Cardiomyopathy*

More difficult to treat are patients with an apical variant of HCM; they have obliteration of the left ventricular chamber with severe diastolic dysfunction. The results of myectomy depend essentially on the experience and competence of the surgeon. Only in specialized centers can myectomy be carried out with a risk of perioperative complications under 1%. The hemodynamic results are usually excellent with a postoperative gradient <10 mm Hg [11]. VSD, atrioventricular block and residual obstruction may complicate a septal myotomy; anyway, incidence is lower for experienced surgeons with a risk <3% in expert hands [12]. Long-term results following surgery are good, with more than 90% of patients being asymptomatic [13]. Septal myectomy is the gold standard in SRT, because of fewer complications and better freedom from redo procedures, with a better long term outcome rather

SAM describes the dynamic movement of the MV during systole anteriorly toward the LVOT. It occurs in 31–61% of HCM patients, and it is associated with

SAM-mediated MR typically resolves with extended myectomy alone, anyway, a well comprehension of all the mechanisms that can predispose to or precipitate SAM, is important, in order to treat this mechanism. Factors predis-

• anterior displacement of MV (any anatomical or surgical translocation of the MV anteriorly will increase the forces acting to draw the MV anteriorly that

• low anterior—posterior (A-P) length ratio (A-P leaflet length ratio <1.3 is a

• distance reduction between MV coaptation point and septum

*DOI: http://dx.doi.org/10.5772/intechopen.86816*

than septal ablation.

**6.1 SAM correction**

posing to SAM are:

**6. Adjuncts to septal myectomy**

a. structural anomalies such as:

• bulging septum

• chordal anomaly

b.geometric factors such as:

• annular undersizing

may precipitate SAM)

risk factor for SAM)

• reduced mitral-aortic angle (<15°)

• small left ventricular chamber

• papillary muscle displacement

• redundant anterior or posterior leaflets

resting LVOT obstruction in 25–50% of them [14].

*Surgical Treatment of Hypertrophic Obstructive Cardiomyopathy DOI: http://dx.doi.org/10.5772/intechopen.86816*

More difficult to treat are patients with an apical variant of HCM; they have obliteration of the left ventricular chamber with severe diastolic dysfunction. The results of myectomy depend essentially on the experience and competence of the surgeon. Only in specialized centers can myectomy be carried out with a risk of perioperative complications under 1%. The hemodynamic results are usually excellent with a postoperative gradient <10 mm Hg [11]. VSD, atrioventricular block and residual obstruction may complicate a septal myotomy; anyway, incidence is lower for experienced surgeons with a risk <3% in expert hands [12]. Long-term results following surgery are good, with more than 90% of patients being asymptomatic [13]. Septal myectomy is the gold standard in SRT, because of fewer complications and better freedom from redo procedures, with a better long term outcome rather than septal ablation.
