A 62-year-old man was referred for management of symptomatic hypertrophic obstructive cardiomyopathy (HOCM). For the past 20 years, he has had a history of syncope after recovering from anesthesia for minor outpatient surgery. He was resuscitated with fluids before discharge and did well. About 8 years ago, after another postoperative syncopal episode, a murmur was detected and an echocardiogram confirmed the diagnosis of HOCM. He could only tolerate a low dose of β-blockers due to his low blood pressure. His dyspnea has progressively worsened, and now he is dyspneic with usual activity (New York Heart Association class III). He also feels dizzy and needs to hold on to the hand rail while climbing up stairs. He does not have angina or palpitations. There is no family history of HOCM or sudden death.
Examination reveals a thin and lean gentleman. He has a bisferiens pulse. His pulse rate is 60 bpm, and his blood pressure is 100/65 mm Hg. He has no signs of heart failure. The second heart sound is paradoxically split, and he has a fourth heart sound. He has a 3/6 systolic murmur over the precordium and a blowing pansystolic murmur at the apex. The murmur increases significantly with Valsalva and with standing.
The electrocardiogram reveals left ventricular hypertrophy with strain pattern. An echocardiogram reveals asymmetric basal septal hypertrophy (Figure 28-1) and systolic anterior motion of the mitral valve (Figure 28-2)with left ventricular outflow gradient of 56 mm Hg at rest (Figure 28-3) and 64 mm Hg with Valsalva (Figure 28-4). After discussing all options for septal reduction therapy, he elects to have alcohol septal ablation.
HOCM was initially described in by Brock in 1957 in a surgical patient.1 In 1958, Teare described the anatomy of 8 young patients who had a sudden death and asymmetric septal hypertrophy.2 In the 1960s, Braunwald described the pathophysiology of this new disease state.3 For many years, it was debated whether the left ventricular outflow tract (LVOT) obstruction was a true obstruction or a functional obstruction due to the hyperdynamic ventricle. Surgical myectomy relieved the obstruction and symptoms, proving that it was a true obstruction.4 Patients who are medically refractory and have LVOT obstruction can be managed by surgical myectomy or alcohol septal ablation. Surgical myectomy has a low mortality (<1%) only in select tertiary centers, but mortality varies from 3.8% to 18% in high- versus low-volume centers.5
In 1994, Dr. Ulrich Sigwart performed the first alcohol septal ablation procedure in a patient who was a poor candidate for surgical myectomy.6 The patient made a smooth recovery with complete resolution of gradients and relief of symptoms. Dr. William Spencer pioneered this procedure in the United States in 1996. Since then, this procedure has become the preferred septal reduction therapy for older patients and also for younger patients who prefer it over surgical myectomy.
Alcohol septal ablation is a percutaneous septal reduction therapy for HOCM (Tables 28-1, 28-2, 28-3). In symptomatic or medically refractory patients with LVOT obstruction due to asymmetric septal hypertrophy and systolic anterior motion of the mitral valve, absolute alcohol is injected into an appropriate septal artery to produce a targeted infarction of the hypertrophied muscle. This results in akinesis and thinning of the offending septum, thus effectively relieving the obstruction and thereby relieving the symptoms. The outcomes of this procedure are favorable and comparable to surgical myectomy.7,8
| Hyperdynamic left ventricle with midcavitary obstruction (Figure 28-5) |
| Subaortic obstruction–LVOT membrane (Figure 28-6) |
| Valvular aortic stenosis (Figure 28-7) |
| Supravalvular aortic stenosis (Figure 28-8) |
| Takotsubo cardiomyopathy (Figure 28-9) |
Figure 28-5
(A) The apical 3-chamber view shows the hourglass appearance of the left ventricle with a mid-cavitary obstruction. (B) Color Doppler shows acceleration of flow at the site of mid-cavitary narrowing. (C) Pulse Doppler tracing in the mid-ventricle shows a late peaking gradient consistent with mid-cavitary obstruction from a hyperdynamic ventricle.
Figure 28-6
This patient was referred for alcohol septal ablation. (A) Parasternal long axis view shows an LVOT membrane causing the obstruction. (B) In the apical 3-chamber view, the color Doppler shows an eccentric aortic insufficiency jet in diastole, which is often seen with LVOT membrane causing obstruction. Aortic insufficiency is very uncommon with HOCM physiology.
Figure 28-7
(A) In the apical 5-chamber view, the calcified aortic valve is seen with aortic root dilatation. (B) The color Doppler shows the acceleration of flow at the level of the aortic valve. (C) The early peaking continuous-wave contour is consistent with the obstruction at the level of the aortic valve.
Figure 28-8
This patient was referred for evaluation of a systolic murmur at the base. (A) The parasternal long axis shows an unobstructed LVOT and a normal-looking aortic valve. There is narrowing of the aorta beyond the aortic valve at the sinotubular level. (B) Continuous-wave Doppler confirmed the presence of severe supravalvular aortic stenosis with mild aortic regurgitation.
Figure 28-9
This patient was diagnosed with takotsubo cardiomyopathy. (A) The apical 3-chamber view shows the apical ballooning. The hyperdynamic base and the systolic anterior motion of the mitral valve produced LVOT obstruction. (B) Continuous-wave Doppler shows the typical late-peaking, dagger-shaped gradient of LVOT obstruction. The LVOT gradient disappeared completely with normalization of left ventricular function in 3 days.
| Other cause of left ventricular outflow tract obstruction |
| Intrinsic mitral valve disease |
| Coronary artery disease needing bypass surgery |
| Age <21 years (relative contraindication <40 years when myectomy is reasonable option) |
| Septal thickness >30 mm |
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