**3. Surgical indication**

*Cardiac Surgery Procedures*

mechanism of any obstruction. In addition, mitral valve (MV) apparatus can be adequately studied, in order to recognize any systolic distortion of the MV associated with systolic anterior motion (SAM) that often leads to secondary MR (**Figure 1**). Despite medical therapy (treatment with B-blockers or, sometimes, Verapamil) is the first-line therapy for symptomatic patients with LVOT obstruction [1], a large proportion of patients with dynamic obstruction remain symptomatic so, a septal reduction treatment (SRT) is needed in order to relief of the symptoms. This can take the form of either septal myectomy or percutaneous alcohol ablation of the septum [5]. In this chapter we will describe the current surgical management of HOCM.

*Transthoracic echocardiography showing LVOT obstruction (A), with a resting LVOT gradient of 77 mmHg (B) and severe MR, due to SAM (C). Figure courtesy of non-invasive cardiology diagnostic laboratory,* 

*Cardiology Department, L. Sacco Hospital, Via G.B. Grassi 74, Milano, Italy.*

Morphology is variable, common variants being basal, mid-ventricular, apical, and diffuse types have been described. Maron classification reported 4 variants of

• Type 1: hypertrophy (10% of patients) confined to the anterior portion of the

• Type 2: hypertrophy (20% of patients), involves the anterior and posterior

• Type 3: hypertrophy (52% of patients), involves the anterior and posterior

• Type 4: hypertrophy (18% of patients), involves left ventricular regions other

portion of the ventricular septum as well as the lateral free wall;

than the anterior septum and the posterior free wall.

**2. Anatomical classification of HCM**

portion of the ventricular septum;

ventricular septum;

**108**

HCM [6]:

**Figure 1.**

ACC/AHA and ESC guidelines recommend that septal reduction therapy should be performed only by experienced operators, working as part of a multidisciplinary team expert, in the management of HCM [1, 7]. A SRT should be performed in presence of:

