Hypertrophic cardiomyopathy septal myectomy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org]; Cafer Zorkun, M.D. [mailto:zorkun@perfuse.org]; Caitlin J. Harrigan [mailto:charrigan@perfuse.org]; Martin S. Maron, M.D.; Barry J. Maron, M.D.;

Overview
Septal myectomy is a surgical treatment for hypertrophic cardiomyopathy (HCM). Septal myectomies have been successfully performed for more than 25 years.

History
It has been performed successfully for more than 25 years.

Indications
Surgical septal myectomy is the gold standard for relief of symptoms for patients who do not experience relief of symptoms from medications.

Technique

 * It involves a midline thoracotomy (general anesthesia, opening the chest, and cardiopulmonary bypass) and removing a portion of the interventricular septum.


 * A modification of the Morrow myectomy termed extended myectomy, mobilization and partial excision of the papillary muscles has become the excision of choice.


 * In selected patients with particularly large redundant mitral valves, anterior leaflet plication may be added to complete separation of the mitral valve and outflow.

Efficacy and Procedural Success
Surgical septal myectomy uniformly decreases left ventricular outflow tract obstruction and improves symptoms, and in experienced centers has a surgical mortality of 1%.

Surgical myectomy resection focused just on the subaortic septum, to increase the size of the outflow tract to reduce Venturi forces may be inadequate to abolish systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. With this limited sort of resection the residual mid-septal bulge still redirects flow posteriorly: SAM persists because flow still gets behind the mitral valve. It is only when the deeper portion of the septal bulge is resected that flow is redirected anteriorly away from the mitral valve, abolishing SAM .

Outcomes
Septal myectomy is associated with a low perioperative mortality and a high late survival rate. A study at the Mayo Clinic found surgical myectomy performed to relieve outflow obstruction and severe symptoms in HCM was associated with long-term survival equivalent to that of the general population, and superior to obstructive HCM without operation. The results are shown below:

* Includes 0.8% operative mortality.

Comparison with alcohol ablation
Either alcohol septal ablation or myectomy offers substantial clinical improvement for patients with hypertrophic obstructive cardiomyopathy.

Hemodynamic resolution of the obstruction and its sequelae is more complete with myectomy.

==2011 ACCF/AHA Guideline Recommendations: Septal Myectomy ==

{{cquote|

Class IIa
1. Consultation with centers experienced in performing both surgical septal myectomy and alcohol septal ablation is reasonable when discussing treatment options for eligible patients with HCM with severe drug-refractory symptoms and LVOT obstruction. (Level of Evidence: C)

2. Surgical septal myectomy, when performed in experienced centers, can be beneﬁcial and is the ﬁrst consideration for the majority of eligible patients with HCM with severe drug-refractory symptoms and LVOT obstruction.(61,62,155,273–275) (Level of Evidence: B)

3. Surgical septal myectomy, when performed at experienced centers, can be beneﬁcial in symptomatic children with HCM and severe resting obstruction (>50 mm Hg) for whom standard medical therapy has failed.(276) (Level of Evidence: C)}}

Guideline Resources

 * ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities


 * The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in Collaboration with the European Heart Rhythm Association


 * 2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy

Related Chapters

 * Alcohol septal ablation