**Abstract**

Hypertrophic cardiomyopathy is a unique myocardial disorder that can present in all ages from neonate to adults and has strong genetic basis. Several key features characterize hypertrophic cardiomyopathy. These include: the presence of left ventricular hypertrophy that can not be explained by another etiology, and left ventricular outflow tract obstruction secondary to systolic anterior motion of the anterior mitral valve leaflet with varying degrees of mitral valve regurgitation. Surgical septal myectomy continues to be the standard line of treatment when medical therapy fails or become intolerable. We summarize in the current chapter the technical tips and pitfall of septal myectomy, its alternatives/adjuncts and its outcomes.

**Keywords:** hypertrophic cardiomyopathy, septal reduction, septal myectomy, subaortic stenosis, left ventricular outflow tract obstruction

## **1. Introduction: history**

Brock and Teare in 1958 reported the first pathological case that drew the attention to HCM, while the first surgical procedure to address HCM was credited to Cleland and colleagues in the same year [1]. The "Morrow" operation was the main surgical procedure for years since it was initially reported by Morrow and Brockenbrough in 1960 [2].

Mitral valve replacement has been historically considered a way of eliminating the LVOTO by eliminating SAM, however with appropriate and complete septal myectomy, this is rarely considered an option in the current era except in the presence of unrepairable concomitant mitral valve disease.

Surgical septal myectomy; however, has evolved over the years from the traditional "Morrow" operation to the current "extended left ventricular septal myectomy" to ensure complete elimination of recurrence or residual LVOTO as will be discussed in the current chapter.

### **2. Background**

Hypertrophic cardiomyopathy (HCM) is a unique myocardial disorder that is characterized by the presence of dynamic left ventricular outflow tract (LVOT) obstruction (LVOTO) and systolic anterior motion (SAM) of the anterior mitral valve leaflet with resultant various degrees of mitral regurgitation. HCM was previously known as idiopathic hypertrophic subaortic stenosis (IHSS) or asymmetric septal hypertrophy which is due to the presence of left ventricular hypertrophy that can not be explained by other pathology. Another key feature in this unique disease.

HCM has been one of the main causes of sudden death in young adults and athletes. Patients may present with a variety of clinical pictures that range from completely asymptomatic to exertional fatigue, chest pain, and/or shortness of breath.

The first line treatment in HCM continued to be medical therapy especially in those symptomatic with LVOTO [3]. Septal reduction therapy should be considered for those who failed or became intolerant to medical therapy [4].
