Management of Hypertrophic Obstructive Cardiomyopathy
Mostafa Mahmoud Atta Mahmoud;
Abstract
Based on over five decades of worldwide experience, the European Society of Cardiology (ESC) 2014 (ESC Guidelines on diagnosis and management of hypertrophic cardiomyopathy), and the recent American College of Cardiology guidelines in 2011, and American College of Cardiology-European Society of Cardiology Expert Consensus Guidelines in 2003, septal myectomy is considered the gold-standard strategy for the relief of drug-refractory symptoms in HCM patients with LV outflow obstruction.
When surgical septal myectomy was initially introduced in the early 1960s, it was regarded as revolutionary and has subsequently stood the test of time. The classic myectomy (Morrow operation) relieves obstruction by resection of a relatively small amount of muscle from the proximal ventricular septum, thereby widening the outflow tract and abolishing flow drag (or Venturi) forces that promote systolic contact between mitral valve and hypertrophied septum, resulting in immediate gradient reduction. More recently, some surgeons have creatively modified the myectomy resection to be wider and to extend more distally, allowing more complete reconstruction of the LV outflow tract, which may be necessary in some patients.
Some patients indicated for surgery were at high surgical risk with various co-morbidities, some others refuse surgery, and some centers have no available surgical expertise. Hence, other alternative therapeutic options evolved over time, the most important and still practiced in a wide scale is Alcohol septal ablation (ASA), which was first introduced in 1995. Ethanol is injected into a septal perforator branch of the left anterior descending coronary artery to intentionally induce limited myocardial infarction at the site of septal hypertrophy with transient drop in gradient as a result of stunning, but usually ultimate resolution of obstruction requires several months of septal remodeling.
There was a high initial enthusiasm for alcohol septal ablation because early results demonstrated that relief of obstruction and improvement of symptoms could be accomplished with a low procedural complication rate. And although surgical myectomy was limited to a few tertiary referral centers, many catheterization laboratories across the world began to perform alcohol septal ablation. But the continued decrease in operative mortality and increase in overall success rate of septal myectomy, primarily due to advances in surgical techniques, myocardial protection, and improvements in the understanding of the haemodynamic abnormalities and pathophysiology of obstructive hypertrophic cardiomyopathy, as well as the fact that although the initial results for ASA are satisfactory, it is not free of complications and the long-term follow-up is yet not as well-known as the follow-up of the surgical outcomes, all of that have resulted in septal myectomy continued being the first and preferred treatment option for most patients.
In the past few years, following the example of most experienced groups, we have gone ahead with myectomy up to the base of the papillary muscles (extended myectomy), and we have used as a routine, measuring of intra-operative post-myectomy gradient. It is recommended that return to cardiopulmonary bypass for expansion of septal myectomy should always be performed when the intra-operative LVOT residual gradient exceeds 25 mmHg.
Reports from centers with large myectomy programmes as Mayo Clinic, Cleveland Clinic, and Toronto General, in which all have documented the dramatic and definitive benefits with septal myectomy, with low early mortality (<1%), and morbidity, improved quality of life, and excellent late survival. In most patients, symptomatic improvement was already evident in the first days after myectomy. This can be explained by the underlying pathophysiology of the disease; surgical myectomy in HCM relieves the high LV systolic pressure overload due to the LV outflow gradient, as well as the volume overload secondary to mitral valve regurgitation, in a ventricle with a high end-diastolic pressure and a small cavity but preserved ejection fraction. Therefore, in most HCM patients, LV haemodynamics and symptoms improve, often dramatically, within days after surgery.
In Egypt, the lack of proper diagnostic tools in remote areas, lack of clinical screening and genetic counseling in families with HCM, inaccurate family history, and the delay in seeking medical care, combined with false impression among physicians of a benign course of the disease, all participated in making the Egyptian patients with symptomatic HOCM indicated for surgery present with more advanced symptoms especially dyspnea, with higher LVOT gradients than most of the reported studies.
When surgical septal myectomy was initially introduced in the early 1960s, it was regarded as revolutionary and has subsequently stood the test of time. The classic myectomy (Morrow operation) relieves obstruction by resection of a relatively small amount of muscle from the proximal ventricular septum, thereby widening the outflow tract and abolishing flow drag (or Venturi) forces that promote systolic contact between mitral valve and hypertrophied septum, resulting in immediate gradient reduction. More recently, some surgeons have creatively modified the myectomy resection to be wider and to extend more distally, allowing more complete reconstruction of the LV outflow tract, which may be necessary in some patients.
Some patients indicated for surgery were at high surgical risk with various co-morbidities, some others refuse surgery, and some centers have no available surgical expertise. Hence, other alternative therapeutic options evolved over time, the most important and still practiced in a wide scale is Alcohol septal ablation (ASA), which was first introduced in 1995. Ethanol is injected into a septal perforator branch of the left anterior descending coronary artery to intentionally induce limited myocardial infarction at the site of septal hypertrophy with transient drop in gradient as a result of stunning, but usually ultimate resolution of obstruction requires several months of septal remodeling.
There was a high initial enthusiasm for alcohol septal ablation because early results demonstrated that relief of obstruction and improvement of symptoms could be accomplished with a low procedural complication rate. And although surgical myectomy was limited to a few tertiary referral centers, many catheterization laboratories across the world began to perform alcohol septal ablation. But the continued decrease in operative mortality and increase in overall success rate of septal myectomy, primarily due to advances in surgical techniques, myocardial protection, and improvements in the understanding of the haemodynamic abnormalities and pathophysiology of obstructive hypertrophic cardiomyopathy, as well as the fact that although the initial results for ASA are satisfactory, it is not free of complications and the long-term follow-up is yet not as well-known as the follow-up of the surgical outcomes, all of that have resulted in septal myectomy continued being the first and preferred treatment option for most patients.
In the past few years, following the example of most experienced groups, we have gone ahead with myectomy up to the base of the papillary muscles (extended myectomy), and we have used as a routine, measuring of intra-operative post-myectomy gradient. It is recommended that return to cardiopulmonary bypass for expansion of septal myectomy should always be performed when the intra-operative LVOT residual gradient exceeds 25 mmHg.
Reports from centers with large myectomy programmes as Mayo Clinic, Cleveland Clinic, and Toronto General, in which all have documented the dramatic and definitive benefits with septal myectomy, with low early mortality (<1%), and morbidity, improved quality of life, and excellent late survival. In most patients, symptomatic improvement was already evident in the first days after myectomy. This can be explained by the underlying pathophysiology of the disease; surgical myectomy in HCM relieves the high LV systolic pressure overload due to the LV outflow gradient, as well as the volume overload secondary to mitral valve regurgitation, in a ventricle with a high end-diastolic pressure and a small cavity but preserved ejection fraction. Therefore, in most HCM patients, LV haemodynamics and symptoms improve, often dramatically, within days after surgery.
In Egypt, the lack of proper diagnostic tools in remote areas, lack of clinical screening and genetic counseling in families with HCM, inaccurate family history, and the delay in seeking medical care, combined with false impression among physicians of a benign course of the disease, all participated in making the Egyptian patients with symptomatic HOCM indicated for surgery present with more advanced symptoms especially dyspnea, with higher LVOT gradients than most of the reported studies.
Other data
| Title | Management of Hypertrophic Obstructive Cardiomyopathy | Other Titles | طرق علاج ضعف عضلة القلب المتضخمة الإنسدادية | Authors | Mostafa Mahmoud Atta Mahmoud | Issue Date | 2015 |
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