Radiofrequency lesions produced by handheld temperature controlled probes for use in atrial fibrillation surgery

• Published in: European journal of cardio-thoracic surgery 2001-12, Vol.20 (6), p.1188-1193
• Main Authors: Thomas, Stuart P., Nicholson, Ian A., Nunn, Graham R., Ross, David L.
• Format: Article
• Language: English
• Subjects: Ablation; Animals; Atrial fibrillation; Atrial Fibrillation - surgery; Biological and medical sciences; Catheter Ablation - instrumentation; Catheter Ablation - methods; Diseases of the cardiovascular system; Dogs; Electrodes; Medical sciences; Myocardium - pathology; Radiofrequency; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Temperature
• ISSN: 1010-7940; 1873-734X
• DOI: 10.1016/S1010-7940(01)00986-1

Objectives: Detailed analysis of the size and shape of lesions produced by handheld radiofrequency ablation devices at open heart surgery has not been reported previously. Methods: Radiofrequency lesions were made from the epicardial surface of the cardiac ventricles in open-chested dogs. The effects of electrode size, electrode temperature and duration of ablation were studied. In a second group of experiments simultaneous multielectrode ablation was performed on the ventricular epicardium after cold cardioplegia. Results: Using a single 12×2.5 mm electrode and a target temperature of 80°C the lesion depth increased from 3.8±0.9 mm at 15 s, to 6.1±0.9 mm at 120 s (P=0.01). Increasing the target temperature from 70 to 90°C (for 60 s) increased lesion depth from 5.0±1.2 to 5.6±1.7 mm (P=0.2). There was no difference in depth of lesions with the two electrode widths (4.0±0.5 mm (large) vs. 3.9±1.0 mm (small)). Lesions produced using the multielectrode probe (80°C, 60 s) were 30–35 mm long with even penetration into the tissue. The mean depth of these lesions on microscopic sections was 3.9 mm. The mean width was 7.1 mm. Conclusions: Handheld probes can be used to make deep linear lesions in the myocardium. Lesions expand rapidly and are wider than they are deep. A mulitelectrode ablation device allows rapid formation of linear lesions.