Case presentation

A 62-year-old woman with hypertrophic obstructive cardiomyopathy was referred for alcohol septal ablation. Her physician first noted a murmur around age 50 during a routine physical examination performed prior to knee surgery, and echocardiographic evaluation confirmed severe asymmetric septal hypertrophy. The septum measured in excess of 2 cm. There was also systolic anterior motion of the mitral valve and a resting gradient in the left ventricular outflow tract of 50 to 80 mmHg with a provokable gradient of 115 mmHg. She was prescribed beta-blocker therapy and initially was asymptomatic; however, over the past few years she had noted progressive dyspnea with exertion, presyncope, and chest tightness. Her symptoms have progressed to the point where she is unable to perform housework without having to stop because of dyspnea or dizziness. In addition to arthritis, she has a history of paroxysmal atrial fibrillation and becomes severely symptomatic during these episodes. She is currently in sinus rhythm and is maintained on warfarin and metoprolol. There is no family history of sudden cardiac death or hypertrophic cardiomyopathy. On physical examination, she appeared healthy with a blood pressure of 160/80 mmHg in both arms. Jugular venous pressure was normal and lung fields were clear. The cardiac exam was notable for the presence of normal first and second sounds with a loud systolic crescendo-decrescendo murmur heard over the apex and radiating to the base; this murmur increased dramatically when the patient moved from the supine to upright position. A 12-lead electrocardiogram revealed her to be in sinus rhythm with left ventricular hypertrophy. She was referred for cardiac catheterization and possible alcohol septal ablation.

Cardiac catheterization

Right heart catheterization revealed a mean right atrial pressure of 4 mmHg, a pulmonary artery pressure of 34/14 with a mean of 21 mmHg, and a mean pulmonary capillary wedge pressure of 13 mmHg. The aortic pressure waveform exhibited the characteristic “spike and dome” morphology seen in hypertrophic obstructive cardiomyopathy (Figure 48-1). A multipurpose catheter with an end-hole and two side-holes at the tip was positioned in the left ventricular cavity. Simultaneous recording of left ventricular and femoral arterial pressure revealed a systolic gradient in excess of 100 mmHg at baseline; with provocation using a post-premature ventricular contraction the gradient exceeded 200 mmHg (Figures 48-2, 48-3). A slow pull-back of the catheter recorded no pressure gradient across the aortic valve (Figure 48-4). Left coronary angiography demonstrated several septal perforators appropriate for alcohol septal ablation (Figure 48-5 and Video 48-1).

FIGURE 48-1 This is an aortic pressure (AO) tracing demonstrating the characteristic “spike and dome” configuration to the aortic waveform present in hypertrophic obstructive cardiomyopathy (PA = pulmonary artery pressure).

FIGURE 48-2 A large gradient is present at rest in the left ventricular outflow tract.

FIGURE 48-3 After provocation with a premature ventricular contraction (PVC), there is a marked increase in the degree of obstruction, shown in the post-PVC beat. The aortic pressure has also dropped in the post-PVC beat (arrow), known as the “Brockenbrough-Braunwald” sign.

FIGURE 48-4 As the end-hole catheter positioned in the left ventricle is slowly withdrawn, the presence of an intraventricular pressure gradient is appreciated; there is no gradient across the aortic valve (arrow).

FIGURE 48-5 This right anterior oblique left coronary angiogram with cranial angulation demonstrates the presence of several prominent septal perforators (arrows) from the left anterior descending artery.

To perform the alcohol septal ablation procedure, the operator first positioned a temporary pacemaker into the right ventricular apex and tested the threshold to ensure capture. An angioplasty guide catheter was engaged into the left coronary ostium and 50 U/kg of unfractionated heparin were administered. A floppy-tipped, 0.014 inch guidewire was advanced into the larger of the first septal branches and a 2.0 mm diameter by 8 mm long over-the-wire balloon catheter was advanced over the wire into the proximal segment of the first septal perforator. The operator inflated the balloon and injected iodinated contrast into the left coronary artery to prove that the balloon was occlusive, thus isolating the septal perforator from the left coronary circulation (Figure 48-6 and Video 48-2). The operator then removed the 0.014 inch wire from the balloon catheter and, with the balloon still inflated, injected iodinated contrast through the lumen of the balloon to show that there was no leakage of contrast from the septal artery to the left anterior descending artery (Figure 48-7