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Advanced Hypertrophic Obstructive Cardiomyopathy Treated by Percutaneous Alcohol Septal Ablation (I)

- Operator : Myeong-Ki Hong, MD, PhD / Seung-Jung Park, MD, PhD, Korea
Case presentation
A 28-year-old man was referred to the Asan Medical Center for treatment of advanced hypertrophic obstructive cardiomyopathy. On admission, he complained of shortness of breath (class III-IV, New York Hospital Association classification) with 2 years of medical treatment. The patient had a 4/6 ejection murmur that was aggravated by the Valsalva maneuver, but which diminished when he squatted.
Baseline study
The electrocardiogram showed pronounced left-ventricular hypertrophy with strain, and echocardiography showed a hypercontractile left ventricle, a variable pressure gradient across the left-ventricular outflow tract, typical systolic anterior movement of the mitral valve, and mitral incompetence (Figure 1, Figure 2). A peak instantaneous pressure gradient of left ventricular outflow under basal (resting) conditions was 74 mmHg (Figure 3).
Cardiac catheterization
Left and right heart catheterization was carried out via the right femoral artery under local anaesthesia. Left-ventricular angiography showed a hypercontractile left ventricle and a typical systolic constriction below the aortic valve (figure 4). There was a 100 mmHg resting
intraventricular pressure gradient / measured simultaneously with the trans-septal
Brockenbrough catheter and with a 7Fr pigtail catheter. The gradient increased to 190 mmHg with postextrasystolic potentiation.
Procedure

At first, a temporary pacemaker was placed in the apex of the right ventricle. A 7 Fr sheath was inserted through right femoral artery and the left coronary was engaged with a 7 Fr Judkins left catheter. The first major septal branch of the anterior descending coronary artery was identified (Figure 5) and catheterized with a 2.0 x 20 mm Ranger balloon (Figure 6). The myocardium perfused by this vessel was enhanced by contrast injections through the balloon catheter with transthoracic echocardiography. After intravenous administration of 3 mg morphine, 3 mL absolute alcohol was slowly injected through the inflated balloon into the vessel and left for 5 min before the balloon was deflated. The pressure gradient was abolished seconds after the alcohol injection, and it failed to reappear after balloon deflation. The patient reported moderate chest discomfort only at the start of the alcohol injection. After the procedure, the left-ventricular angiogram showed no difference in end-diastolic volume but the end-systolic volume was larger and no subaortic obstruction was visible during systole. Final angiography showed no flow in the first septal branch (Figure 7).

The systolic anterior movement of the mitral valve remained visible on echocardiography despite the lack of a significantly accelerated flow. Creatine kinase activity rose to a maximum of 3638 IU (with the MB isoenzyme 716 IU) within hours of the procedure and fell rapidly thereafter. The patient made an uneventful recovery and was discharged 6 days after the intervention. Six months later he had a 1/6 systolic ejection murmur and his dyspnea class was reduced to class I. Doppler echocardiography showed a nonsignificant outflow-tract gradient (Figure 8) and disappeared systolic anterior movement of the mitral valve without mitral incompetence (Figure 9).

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