Catheter ablation using ultrasound energy significantly decreased electrogram amplitude (p<0.01) and effectively created deep lesions, though blood coagulation on the catheter tip remains an issue.
Does ultrasound energy ablation effectively create deep myocardial lesions in canine and porcine models?
Ultrasound energy ablation is capable of creating deep lesions in ventricular myocardium, but carries a risk of blood coagulum formation on the catheter tip.
p-value: p=<0.01
UNLABELLED: We examined the efficacy and safety of ultrasound energy in eliminating the arrhythmogenic substrates of atrial as well as ventricular tissue using a newly developed instrument in both in vivo and in vitro experiments. Ultrasound (US) applicators were tested on 79 lesions created on a beating heart in canine cardiac tissue, and on 64 lesions in porcine heart specimens. US lesions were created by using transducers with frequencies around 5-10 MHz. In the in vivo study, we observed a significant decrease in the amplitude of the electrograms recorded from the tip of the ablation catheter during the US application (p < 0.01). In some sites transmural lesions could be created which were well demarcated. Blood coagulum formation was observed on the tip of the ablation catheter on several occasions. In one dog ventricular fibrillation was provoked by the delivery of ultrasound energy to the left ventricle. In the in vitro study, lesion depth increased significantly with a longer duration of energy delivery when the temperature was maintained table (p < 0.001), and the lesion depth increased significantly with higher temperatures of energy delivery when the duration of US application was maintained (p < 0.05). In both cases, no significant change in surface area was observed. The maximum depth of the lesion was 10.3 mm. CONCLUSIONS: An ultrasound energy system is relatively safe and effective for creating lesions large enough to eliminate arrhythmogenic substrates deep in the ventricular myocardium. Although the US system is free from pop phenomenon, the problem of blood coagulation on the catheter tip remains to be settled.
Ohkubo et al. (Thu,) conducted a other in Arrhythmogenic substrates. Catheter ablation using ultrasound energy was evaluated on Amplitude of electrograms and lesion depth (p=<0.01). Catheter ablation using ultrasound energy significantly decreased electrogram amplitude (p<0.01) and effectively created deep lesions, though blood coagulation on the catheter tip remains an issue.