Right Coronary Artery Obstruction After Radiofrequency Current Application at Right Atrial Myocardium in Young Pigs

Anatomical sequelae after creation of right atrial myocardial lesions by radiofrequency current (RFC) application have not been studied in detail in young subjects. During general anesthesia, steerable 6 French electrode catheter, equipped with thermistor at the 4 mm tip electrode, was positioned at the lateral atrial aspect of the tricuspid valve anulus in 10 piglets (german landrace, age 6 weeks, mean body weight 12.5 kg). RFC (500 kHz) was delivered temperature-guided (75 °C) over 30 sec. Right atrial RFC lesions were studied macroscopically and microscopically in 5 animals after 48 hours, the remaining 5 animals were examined after 6 months. After 48 hours, RFC lesions presented as transmural grey-white coagulation necrosis. Lesions were sharply demarcated by lymphocytic wall. Lymphocytic infiltration around the lesions extended to the right coronary artery in animals and to right ventricular myocardium in piglets. After 6 months, lesions consisted of transmural white scar tissue extending to the right ventricular myocardium in animals. Layers of the right coronary artery were affected in pigs. In 2 animals, the lumen of the right coronary artery was obstructed due to intimal thickening by 25 and 40%, respectively. Conclusion: Results should be taken into account when radiofrequency current application at the atrial aspect of the tricuspid valve anulus is considered in infants and small children.