CORONARY-ARTERY INVOLVEMENT EARLY AND LATE AFTER RADIOFREQUENCY CURRENT APPLICATION IN YOUNG-PIGS

Radiofrequency current (500 kHz) was delivered by temperature guidance (75 degrees C) over a 30-second period in 10 young piglets with a ste erable 6F electrode catheter equipped with a thermistor at the 4 mm ti p electrode. Lesions were created at the right atrial aspect of the tr icuspid valve anulus, at the left ventricular myocardium under the lat eral mitral valve anulus, and at the left ventricular apex. After 48 h ours, five animals were randomly sacrificed. Lesions in the five anima ls appeared as transmural gray-white coagulation necrosis. Lymphocytic infiltration around the right atrial lesions extended into the layers of the right coronary artery in four of five animals. After 6 months, lesions consisted of compact fibrous tissue in the remaining five ani mals. Right atrial lesions extended to the layers of the right coronar y artery in four of five pigs. In two animals the lumen of the right c oronary artery was narrowed because of intimal thickening by 25% and 4 0%, respectively. No increase in the lesion size was observed with the growth of the animals. Effects on the right coronary artery as a late sequela after radiofrequency current application may also be possible in human beings and should be considered when radiofrequency current ablation procedures are proposed in infants and young children.