A new strategy for septal ablation with transendocardial ethanol injection using a multifunctional intracardiac echocardiography catheter: a feasibility study in canines.

Objectives: To evaluate the feasibility and safety of a novel multifunctional intracardiac echocardiography catheter for target septal ablation with transendocardial ethanol injection in canines.

Background: Percutaneous transluminal septal myocardial ablation has been the primary catheter-based strategy for the treatment of hypertrophic obstructive cardiomyopathy (HOCM). However, inherent limitations of the technique have reduced its therapeutic efficacy.

Methods: A new catheter (10 F), integrated with a nitinol needle (29 G) and a 6.5-10-MHz, 32-element, side-fire ultrasound imaging transducer, was delivered into the right ventricle in nine canines and the left ventricle in three canines. A 0.3-ml microbubble and 0.5-1.5 ml absolute ethanol were sequentially injected into the interventricular septum. Electrocardiograph recordings were obtained during the whole procedure. Three hours after this operation, the heart was harvested for gross and histological examination.

Results: In all canines, the catheter provided the structural support and helped guide proper needle position within the septum. The microbubble further allowed the confirmation of the needle location through focal echo-density enhancement. Different amounts of ethanol infusion produced a dose-related effect on myocardial ablation. Macroscopic examination showed that the target myocardium became pale with a distinct border between lesions and normal tissue. Hematoxylin and eosin staining further confirmed necrosis within the injection region.

Conclusions: Transendocardial ethanol injection at the interventricular septum resulted in controlled myocardial infarction. In addition, the injection depth could be visually followed using this new system, which may provide a safer and more intuitive method for the treatment of HOCM or other cardiomyopathies.