Left Septal Fascicular Block Following Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy.

Left septal fascicular block, or blockage of the middle fibers of the left bundle branch, is known to be suggestive of a critical proximal obstruction of the left anterior descending coronary artery before its first septal perforator branch. We describe the case of a 68-year-old male who exhibited this transient intraventricular dromotropic disturbance following alcohol septal ablation for hypertrophic obstructive cardiomyopathy.