Intervention in Hypertrophic Obstructive Cardiomyopathy

This article reviews the present status of intervention in hypertrophic obstructive cardiomyopathy. Interventions include pacing, which is best administered by VDD mode with sufficiently short atrioventricular delay as to assure ventricular capture. Occasionally, this may require the addition of atrioiventricular (AV) junctional ablation in order to achieve 100% ventricular capture. This approach alters the left ventricular (LV) contraction sequence, thereby reducing the left ventricular outflow obstruction. VVI pacing is inadequate because of the necessity for atrial contribution to the hypertrophied ventricle. This contribution may he ineffective even with VDD pacing, without the benefit of AV junctional ablation, because of late activation of the left atrium. Ablation of the left bundle branch may also achieve altered contraction sequence of the LV, but experience with this technique is very limited. Two different methods of reduction of the interventricular septum have been proposed. The first is transaortic laser, which has not gained wide acceptance, and the second is a new and promising method that appears to be less traumatic. This is alcohol delivery to the first septal branch of the left anterior descending coronary artery by an angioplasty technique. Surgical approaches include septal myomectomy directly to reduce the obstruction and mitral valve replacement to eliminate the part played in the obstruction by the anterior cusp of the valve. In conclusion, younger patients, even those who are asymptomatic, should be considered for surgical myomectomy, there being little place now for mitral valve replacement. In older patients, pacing and septal chemoablation offer the greatest promise, but their places are not yet fully established . (J Interven Cardiol 1996; 9:399–403)