Abstract 3560: Accurate Targeting of Myocardial Tissue Using High Intensity Focused Ultrasound in Mice
Background: High intensity focused ultrasound (HIFU) can create rapid thermal lesions without direct tissue contact, and may be useful as a less-invasive modality for myocardial ablation. For the clinical application of myocardial ablation, it is necessary to be able to target myocardial tissue accurately. The purpose of this study was to examine the feasibility of HIFU ablation in controlling the location of myocardial lesions in mice.
Methods: HIFU ablation was performed in 10 mice without thoracotomy. The HIFU exposure was provided by a 33-mm diameter, 35-mm focal-length transducer operated at 5.25 MHz and 60.0 W with a pulse duration of one second repeated three times. The focal point was set at the left ventricle anterior septal wall in 5 mice (AS group) and at the posterior wall in 5 mice (P group) under two-dimensional echocardiographic guidance. Four weeks after the procedure, we sacrificed the mice and assessed each lesion histologically.
Results: The mortality of entire group was 20% (0/5 for AS group, 2/5 for P group). Among the mice which survived for four weeks, we found HIFU lesions in the anterior septal wall in all 5 AS group mice, and in the posterior wall in 2 out of 3 P group mice. The remaining P group mouse exhibited a pericardial lesion near the posterior wall.
Conclusions: HIFU can create focal lesions in the desired area of the myocardium from the extracardiac position in mice. With further refinement, HIFU could become a less-invasive means of cardiac ablation with its capability of accurate targetting.