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Transaortic myectomy is the standard treatment for symptomatic patients with hypertrophic obstructive cardiomyopathy that proves to be refractive to medical therapy. We encountered a case that required a modified surgical approach to relieve a left ventricular outflow tract obstruction that could not be adequately resected through the aortic annulus because of poor exposure of the ventricular septum. Persistent high gradients after the 1st operation necessitated a 2nd operation. We used a novel approach via the left ventricular apex that enabled us to resect a large amount of obstructive tissue under direct vision and thereby to relieve the left ventricular outflow tract obstruction.
Hypertrophic obstructive cardiomyopathy (HOCM) is a relatively common genetic disease that affects persons of all ages and has a markedly heterogeneous clinical presentation.1 The diagnosis is made by using echocardiography to identify thickening of the left ventricular (LV) septal wall, a feature not attributed to any other disease.2 Muscular thickening, either alone or in combination with systolic anterior motion (SAM) of the mitral valve, leads to obstruction of the LV outflow tract (LVOT). In hemodynamically relevant cases, this obstruction may lead to irreversible heart failure with systolic dysfunction.3,4 The initial approach to treatment is usually medical (that is, β-blockers, verapamil, or disopyramide). In cases that are unresponsive to medical therapy, invasive measures are necessary to relieve the LVOT obstruction.
During the past 40 years, various surgical procedures have been described for the treatment of HOCM. Alcohol septal ablation (ASA), a relatively new technique, has been used to reduce LVOT gradients in symptomatic patients, but the safety and long-term efficacy of this treatment are questionable.5 Myectomy via a transaortic incision (the Morrow procedure) has been established as the preferred approach.6,7 However, in a small number of patients with anatomic variations, this approach may not be adequate for safe resection of the obstructing tissue. We describe a novel myectomy approach via the LV apex that we performed successfully in a patient who could not be treated effectively via the standard transaortic approach.
In May 2009, our patient, a 56-year-old man with HOCM, was symptomatic (New York Heart Association [NYHA] functional class III) despite maximal medical therapy. Preoperative peak and mean gradients across the LVOT were 80 and 56 mmHg, respectively. Septal thickness, measured by echocardiography, was 21 mm, and SAM of the mitral valve was observed (Fig. 1; Table I).
Because of the patient's body habitus and rotation of the heart, septal exposure during the 1st operative procedure was not suitable for adequate resection through the aortic annulus. Surgery with this approach achieved only a modest reduction of the muscular septum and gradient. Postoperative echocardiography showed mitral SAM and persistently elevated gradients across the LVOT (Table I). The patient remained symptomatic, had no significant change in NYHA functional class, and had persistent exertional dyspnea and occasional episodes of near-syncope.
Two weeks after the 1st operation, a 2nd operation was performed to further resect the hypertrophied septum through the LV apex. A 3-cm incision was made at the ventricular apex, and the LVOT and septal area were inspected. Excessive subaortic hypertrophic muscle was then resected to obtain a pathologic specimen of muscular tissue measuring 4 × 4 × 1 cm. Once the resection was deemed satisfactory, the ventriculotomy was closed with 2-0 Prolene suture reinforced with felt strips. Postoperative echocardiography performed 1 week after surgery showed that the peak gradient had been reduced to 2.6 mmHg and that the SAM had been eliminated (Fig. 2; Table I). In addition, the patient's NYHA functional class improved to class I–II, and the patient was discharged from the hospital in good condition several days later.
Four months after surgery, echocardiography revealed normal LV size, moderate concentric hypertrophy with all segments contracting normally, and a left ventricular ejection fraction of 0.60. The LVOT peak gradient was 6.3 mmHg, and the mean gradient was 3.1 mmHg. No right ventricular abnormality was noted, and mitral valve motion was normal. At follow-up 1 year later, the patient was doing well and was free of symptoms.
The gradient observed in patients with HOCM results from 2 interrelated pathophysiologic conditions: uncontrolled hypertrophy of cardiac muscle within the LVOT; and SAM of the anterior mitral valve leaflet, which dynamically obstructs the LVOT during systole. Standard surgery reduces gradients and abolishes concomitant SAM in 90% of cases, yielding a mortality rate of less than 1% in centers with experience in these procedures.8,9 However, about 3% of patients who undergo septal myectomy need reoperation.10 For more difficult cases, several surgical options have been described. Mitral valve replacement can abolish the outflow gradient and SAM, but it is indicated in only the most intransigent cases.11 Kirklin and Ellis12 described a ventriculotomy via the anterior LV free wall. Although this approach provides accessibility in some difficult cases, the risk of coronary artery injury, heart block, and deleterious effects on LV function make it impractical. Cooley and colleagues13 reported resecting tissue from the right side of the septum to relieve subaortic gradients, but this method has not been widely accepted. More recently, ASA has been advocated as a less invasive but equally effective alternative therapy. According to a consensus document released by the American College of Cardiology on the management of HOCM,5 surgical myectomy clearly remains the “gold standard” treatment for symptomatic patients; yet substantial attention has been given, elsewhere in the medical literature, to ASA as a nonsurgical therapy. The need for a permanent pacemaker is considerably greater after ASA, because ASA produces necrosis that carries a risk of scar-related arrhythmia.14
For our patient, we elected to approach the problem with a myectomy via the LV apex. Surgical exposure of the septum enabled us to effectively resect obstructing tissue that could not adequately or safely be resected via the transannular approach. The patient was relieved of his LVOT obstruction and symptoms. We propose surgical exposure of the septum through the LV apex as a reasonable alternative approach for cases in which the septum cannot be adequately visualized with the standard exposure through the aortic annulus.
Stephen N. Palmer, PhD, ELS, and Nicole Stancel, PhD, contributed to the editing of this manuscript.
Address for reprints: David A. Ott, MD, Texas Heart Institute at St. Luke's Episcopal Hospital, P.O. Box 20345, MC 3-258, Houston, TX 77225