Transapical Approach to Myectomy for Midventricular Obstruction in Hypertrophic Cardiomyopathy

doi:10.1016/j.athoracsur.2013.04.073

The Annals of Thoracic Surgery

Volume 96, Issue 2, August 2013, Pages 564-570

Presented at the Forty-ninth Annual Meeting of The Society of Thoracic Surgeons, Los Angeles, CA, Jan 26–30, 2013.

https://doi.org/10.1016/j.athoracsur.2013.04.073 Get rights and content

Background

Midventricular obstruction in hypertrophic cardiomyopathy (HCM) is less common than subaortic obstruction, and there are few data on outcomes after surgical treatment.

Methods

We reviewed 56 consecutive patients (28 men) with HCM and midventricular obstruction who underwent myectomy between February 1997 and June 2012. Five patients had prior myectomy for subaortic obstruction. Mean age was 42 ± 17 years. Preoperatively, 51% of patients had dyspnea, and the remaining had palpitations (25%), angina (5%), or syncope (9%).

Results

Midventricular obstruction was relieved by means of a transaortic myectomy in 5 patients, a transapical approach in 32 patients, and combined transaortic and transapical incisions in 19 patients. In 13 patients, an apical aneurysm or pouch was repaired at the time of midventricular myectomy. There were no early deaths. Intraoperative intraventricular gradients were reduced from 64 ± 32 mm Hg before myectomy to 6 ± 12 mm Hg postoperatively (p ≤ 0.0001). Early complications included atrial arrhythmias in 5 patients and reoperation for bleeding in 4 patients. Fifty patients had follow-up beyond 30 days (median, 1.6 years; range, 33 days to 13 years). Survival at 1 and 5 years was 100% and 95%, and average New York Heart Association class improved from 2.9 ± 0.7 preoperatively to 1.3 ± 0.6 postoperatively (p = 0.0001). There were no aneurysms related to the apical incision; 2 patients had late reoperation, 1 for resection of right atrial mass to prevent embolus.

Conclusions

A transapical approach allows excellent exposure for midventricular myectomy and relief of intraventricular gradients and related symptoms. There were no complications unique to the apical incision, and 5-year survival was similar to expected survival (95% versus 97%).

Section snippets

Patients and Methods

After obtaining permission from the Mayo Clinic Institutional Review Board, we reviewed the records of 56 patients with HCM and midventricular obstruction who underwent myectomy between February 1997 and June 2012. During this interval 1,644 patients underwent myectomy for HCM-related obstruction. The study included data retrieval from the Mayo Clinic electronic health record, our cardiovascular surgical database, and follow-up questionnaires that include quality-of-life measures. The

Results

Among the 56 patients who underwent myectomy for midventricular obstruction, the mean age was 42 ± 17 years and 28 were men. Presenting symptoms were variable; 51% of patients had dyspnea, 25% had palpitations, 9% presented with syncope, and 5% presented with angina. Other presentations included thromboembolic stroke (2%), ventricular tachycardias (4%), and cardiac arrest (2%). Forty-two percent of patients (n = 23) had an implantable cardiac defibrillator preoperatively. Five patients had

Comment

Midventricular obstruction in HCM is less common than subaortic obstruction; it has a different pathophysiologic mechanism and, in untreated patients, may have a worse prognosis [4]. Unlike subaortic obstruction, which is caused by systolic anterior motion of the mitral valve leaflets, midventricular obstruction is attributable to systolic narrowing of the mid ventricle with apposition of the septum and papillary muscles. Thus, secondary mitral valve regurgitation is uncommon and is not a part

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Septal myectomy is a well-established procedure for septal reduction in patients with obstructive hypertrophic cardiomyopathy (HCM) who have not responded to medical treatment. The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient. Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction, the most common type of HCM. However, transapical myectomy is a useful adjunct for patients with long or midventricular obstruction and is our preferred technique for ventricular enlargement in patients with severe symptomatic diastolic heart failure because of extensive apical hypertrophy. Septal myectomy provides excellent postoperative outcomes as regards symptom relief and functional improvement, and operative morbidity and mortality rates are low in experienced centers. This article summarizes our current surgical management of patients with HCM and details operative methods and outcomes.
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Hypertrophic cardiomyopathy (HCM), the most common inherited cardiomyopathy, exhibits left ventricular hypertrophy not secondary to other causes, with varied phenotypic expression. Enhanced actin-myosin interaction underlies excessive myocardial contraction, frequently resulting in dynamic obstruction within the left ventricle. Left ventricular outflow tract obstruction, occurring at rest or with provocation in 75% of HCM patients, portends adverse prognosis, contributes to symptoms, and is frequently a therapeutic target. Transthoracic echocardiography plays a crucial role in the screening, initial diagnosis, management, and risk stratification of HCM. Herein, we explore echocardiographic evaluation of HCM, emphasizing Doppler assessment for obstruction. Echocardiography informs management strategies through noninvasive hemodynamic assessment, which is frequently obtained with various provocative maneuvers. Recognition of obstructive HCM phenotypes and associated anatomical abnormalities guides therapeutic decision-making. Doppler echocardiography allows monitoring of therapeutic responses, whether it be medical therapies (including cardiac myosin inhibitor therapy) or septal reduction therapies, including surgical myectomy and alcohol septal ablation. This article discusses the hemodynamics of obstruction and practical application of Doppler assessment in HCM. In addition, it provides a visual atlas of obstruction in HCM, including high-quality figures and complementary videos that illustrate the many facets of dynamic obstruction.
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Septal myectomy is indicated in patients with obstructive hypertrophic cardiomyopathy (HCM) who have persistent symptoms despite medical therapy, intolerance of medication side effects, or severe resting or provocable gradients. Septal myectomy at high volume centers is safe, with low operative mortality (1%) and low rates of complications such as complete heart block or ventricular septal defect (3% and 0.5%, respectively). Additionally, improved survival following myectomy has been observed when compared to patients with obstructive HCM managed medically or those with nonobstructive HCM. As a longstanding, quaternary referral center for septal myectomy, our institution has built significant experience and expertise in the surgical and medical management of HCM, including atypical HCM, defined as preadolescent patients, those with mitral valve disease, and those with isolated midventricular obstruction. The most important factor of septal myectomy in achieving complete resolution of obstruction and avoiding recurrence is the apical extent of the myectomy trough, which must extend to the septum opposite the papillary muscles. If this cannot be fully achieved via a transaortic exposure, especially in preadolescents and patients with midventricular obstruction, then a transapical approach may be needed. Mitral valve repair is rarely necessary as SAM-mediated MR resolves with adequate myectomy alone, but mitral repair is performed in cases of intrinsic valvular disease. In this manuscript we provide a summary of current operative techniques and outcomes data from our institution on the management of these various categories of HCM.
Long-term outcomes of surgery for obstructive hypertrophic cardiomyopathy in a pediatric cohort
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Septal reduction therapy via septal myectomy or a modified Konno procedure is the mainstay of therapy for drug-refractory obstructive hypertrophic cardiomyopathy (HCM), although outcomes data on septal myectomy in pediatric patients are limited. We evaluated long-term outcomes following surgery for obstructive HCM in a pediatric cohort.
We retrospectively reviewed patients age ≤18 years with obstructive HCM who underwent a left and/or right ventricular septal myectomy at our institution between 1992 and 2022. Primary endpoints were transplantation-free survival, freedom from HCM-related death, and cumulative probability of HCM-related reintervention. We further evaluated outcomes in patients with and without Noonan syndrome or other RASopathies.
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Surgery for obstructive HCM, including septal myectomy with and without a modified Konno procedure, may be performed with low morbidity and good long-term outcomes in pediatric patients. Recurrent outflow tract obstruction is not uncommon.
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Although septal myectomy is the preferred method of septal reduction in patients with obstructive hypertrophic cardiomyopathy, relatively few surgeons are experienced with the operation. To allow better understanding of pathologic anatomy for surgeons, cardiologists, and anesthesiologists, we propose a nomenclature to assist with surgical definition, planning, and interdisciplinary communication.
In our experience in teaching various surgical approaches to obstructive hypertrophic cardiomyopathy, we have found it beneficial to use a common classification of septal morphology and orientation of the left ventricular outflow tract as viewed by the operating surgeon. Here, we present a useful nomenclature for obstructive hypertrophic cardiomyopathy phenotypes and their surgical implications.
This novel nomenclature should facilitate surgical education and dissemination of expertise for septal myectomy.
Refractory electrical storm in a patient with hypertrophic cardiomyopathy and an implantable cardioverter-defibrillator
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A 63-year-old man with hypertrophic cardiomyopathy (HCM), mid-ventricular obstruction, and an apical aneurysm had an episode of cardiac arrest due to sustained ventricular tachycardia (VT). He was resuscitated and an implantable cardioverter-defibrillator (ICD) was implanted. In the following years, several episodes of VT and ventricular fibrillation were successfully terminated by antitachycardia pacing or ICD shocks. Three years after ICD implantation, he was re-admitted because of refractory electrical storm (ES). Since aggressive pharmacological treatments, direct current cardioversions, and deep sedation were not effective, he underwent epicardial catheter ablation which was successful to terminate ES. However, because of the recurrence of refractory ES after one year, he proceeded to surgical left ventricular myectomy with apical aneurysmectomy which provided him a relatively stable clinical course for six years. Although epicardial catheter ablation may be an acceptable option, surgical resection of apical aneurysm seems to be most efficacious for ES in patients with HCM and an apical aneurysm.
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Original articleAdult cardiacTransapical Approach to Myectomy for Midventricular Obstruction in Hypertrophic Cardiomyopathy

Background

Methods

Results

Conclusions

Section snippets

Patients and Methods

Results

Comment

J Am Coll Cardiol

J Thorac Cardiovasc Surg

J Am Coll Cardiol

J Am Soc Echocardiogr

J Am Coll Cardiol

Asymmetrical hypertrophy of the heart in young adults

Br Heart J

Hypertrophic cardiomyopathy: a systematic review

JAMA

Hypertrophic cardiomyopathy. Clinical spectrum and treatment

Circulation

Original article
Adult cardiac
Transapical Approach to Myectomy for Midventricular Obstruction in Hypertrophic Cardiomyopathy