**10. Septal myectomy after alcohol septal ablation**

 Alcohol septal ablation (ASA) has been considered as an alternative to septal myectomy in suitable patients. It relies on septal artery ablation with subsequent reduction in the basal septal thickness. We do believe it is an alternative for high risk patients and those who deemed not suitable for standard surgical septal myectomy.

 However, it is important to be aware that patients who require septal myectomy after ASA are at high risk for needing a permanent pacemaker and have lower survival compared with those who receive primary surgical septal myectomy [ 25 ]. ASA results in right bundle branch block and standard myectomy will result in left bundle branch block ( **Figure 16** ), thus increasing the chance for needing permanent pacing after surgery.

*Hypertrophic Cardiomyopathy: Surgical Perspectives DOI: http://dx.doi.org/10.5772/intechopen.109568*

#### **Figure 16.**

 *It is not uncommon after septal myectomy to have a left bundle branch block as visualized on this patient postoperative electrocardiogram.* 

 There are also some anatomic substrates that will not be suitable for ASA such as the midventricular and apical variants so as those with significant basal septal thickness (3 cm or more) where surgical septal myectomy would be considered the first line septal reduction modality.

## **11. Right ventricular myectomy**

 A subgroup of patients with HCM, particularly in association with genetic syndromes such as Noonan's, can present with biventricular outflow tract obstruction.

#### **Figure 17.**

 *Right ventricular septal myectomy is done through an incision in the right ventricular outflow tract (RVOT) followed by patch augmentation after completion of the myectomy. RVOT: Right ventricular outflow tract.* 

This is important to recognize during their evaluation and especially if they are being offered surgical myectomy on the left side.

Septal myectomy on the right side is a bit different from the left side. Shaving on the right side of the interventricular septum has to be done with caution to avoid injury to conduction tissue and/or the tricuspid valve apparatus which is different from the left side where there is no septal attachment to the mitral valve. This is usually done through an infundibular incision, followed by patch augmentation of the RVOT (**Figure 17**) [26].
