Effects of intracardiac radiofrequency current application on coronary artery vessels in young pigs

Radiofrequency Current Lesions in Young Pigs. Introduction: Radiofrequency current is widely used in children to ablate accessory AV pathways. Previou s data in a pig model demonstrated coronary artery obstruction adjacent to radiofrequency current lesions 48 hours and 6 months after energy delivery. In the present study, the long-term effects (>6 months) of radiofrequency current application on coronary artery vessels in young pigs are assessed. Methods and Results: Radiofrequency current (500 kHz) was delivered over 30 seconds in ten piglets (mean body weight 12.8 kg) using a steerable 6-Fren ch catheter with a 4-mm thermistor tip electrode (target temperature 75 deg rees C). Lesions were created under fluoroscopic and electrocardiographic g uidance at the lateral right atrial (RA) wall above the tricuspid valve ori fice, and at the lateral left atrial and left ventricular wall adjacent to the mitral valve orifice, Selective coronary angiography and intravascular ultrasound (IVUS) studies were performed 3, 6, 9, and 12 months after energ y application. After 12 months, the lesions were studied pathohistologicall y. All lesions consisted of compact fibrous tissue. RA lesions extended to the adjacent right coronary artery and led to coronary artery involvement w ith increased fibrous tissue in the adventitia and media and intimal thicke ning in three animals. Coronary arterial narrowing was documented by IVUS d uring follow-up in all three cases 9 months after energy application. Angio graphy failed to demonstrate coronary pathology in any of the three animals . Conclusion: The risk of late coronary artery lesions must be considered whe n catheter ablation at the RA wall is planned in children with free-wall ac cessory AV pathways.