Echocardiographic transponder-guided catheter ablation feasibility and accuracy.

Background: The utility of echocardiography for catheter guidance during percutaneous endocardial ablation is increasingly apparent. However, the technique is currently imperfect due to limitations in discerning the ablation electrode from other parts of the catheter shaft.

Purpose: To examine the feasibility and accuracy of echocardiography-guided ablation using commercial ablation catheters fitted with a transponder to improve localization of the ablation electrode.

Methods: Fifteen healthy pigs and five pigs with chronic anterior myocardial infarction were studied. In healthy animals, echocardiographically distinct endocardial sites in right and left cardiac chambers were targeted for ablation. In infarcted animals, the left ventricular infarction border zone was targeted. Both intracardiac (ICE; 12.5 megahertz and 5 megahertz) and transesophageal echocardiographic (TEE) techniques were utilized.

Results: In healthy animals, transponder-guided ablation was feasible with each of the echocardiographic techniques. Accuracy was 82 % (45 of 55 lesions) with ICE-12.5 MHz, 87 % (27 of 31 lesions) with ICE-5 MHz, and 81 % (22 of 27 lesions) with TEE. In infarcted animals, the accuracy was 38 % (3 of 8 lesions) for ICE-5 MHz and 38 % (3 of 8 lesions) for TEE. Errant lesions in healthy animals were observed in earlier experiments, due to operator misinterpretation of the plane of imaging. Errant lesions in infarcted animals were observed throughout the experimental series, and may have been due to a variable relationship between echocardiographic and histologic infarction border zones.

Conclusions: Echocardiographic transponder-guided catheter ablation is feasible. Accuracy for normal endocardial targets was excellent, less so for chronic infarction border.