Safety of radiofrequency ablation of myocardium and lung adjacent to the heart: An animal study

Background The purpose of this work was to assess the feasibility and safety of applying radiofrequency to lung parenchyma adjacent to the heart and to evaluate the clinical impact and the histopathological damage to the heart caused by radiofrequency electrodes penetrating the pericardium and the myocardium. Materials and methods. Three sheep underwent pulmonary radiofrequency ablation adjacent to the heart at 460 kHz with target temperatures of 70degreesC for 10 min at a maximum deployment of 4 cm. The animals were euthanized at the end of the procedure and the lungs and hearts were removed for gross pathological examination. Histopathology on selected hematoxylin & eosin-stained specimens was performed. Results. Circulating blood had a "heat-sink" effect with tissue temperature at the electrode tips adjacent to the heart not exceeding 47degreesC. Ventricular tachycardia and occasional extrasystoles were the only adverse reactions noted, even when electrodes penetrated the myocardium heart rhythm returned to sinus upon discontinuation of the radiofrequency energy delivery. Conclusions. Pulmonary radiofrequency ablation next to the heart is a relatively safe procedure. Major concern is that incomplete tumor ablation adjacent to the heart is probable as a result of the cooling effect of the circulating blood. (C) 2003 Elsevier Inc. All rights reserved.