Induction of subaortic septal ischaemia to reduce obstruction in hypertrophic obstructive cardiomyopathy : Studies to develop a new catheter-based concept of treatment

To develop a new catheter-based method of treatment in patients with hypertrophic obstructive cardiomyopathy. Does abolition of the blood supply to the subaortic part of the septum lead to regional myocardial ischaemia and a decrease in the left ventricular outflow tract gradient? To find this out, in 10 consecutive patients the first larger septal branch of the left anterior descending coronary artery was temporarily occluded with conventional percutaneous transluminal coronary angioplasty. The intracoronary electrocardiogram was registered for objective verification of the intended ischaemia. The intraventricular pressure was measured at rest and at the post extrasystolic beat under programmed electrostimulation of the right ventricle. During occlusion, regional ischaemia was observed in all patients. Simultaneously, there was a significant reduction of the intraventricular gradient from 56.2 mmHg to 32.2 mmHg (P < 0.05) followed by an increase from 32.2 mmHg to 61.1 mmHg (P < 0.01) after release of occlusion of the septal branch. During ischaemia there was no increase in left ventricular end-diastolic pressure. We conclude that the results form the basis for a new catheter interventional therapy in hypertrophic obstructive cardiomyopathy.