Background: The application of intracardiac echocardiography (ICE) in atrial fibrillation (AF) ablation may increase the success rate and decrease the complication rate of the procedure. We present our preliminary observations concerning the utility of ICE in AF ablation.
Methods: In February and July 2004 we performed 6 radiofrequency (RF) ablations guided by ICE (EP Med Systems) in patients with atrial tachyarrhythmia. All patients had undergone at least three months of oral anticoagulation therapy before the procedure. For three days before ablation enoxaparin was administered. During each procedure the ICE catheter was placed in the right atrium. Transseptal puncture was guided by fluoroscopy and ICE imaging. After placement of the introducer in the left atrium a bolus of heparin (100 IU/kg) was administered followed by additional boluses (1000 IU/h). Electroanatomical isolation of the pulmonary vein ostia was performed with a 4 mm ablation catheter (RF energy was set at 50–55^oC and 25–35 W). RF energy was titrated if microbubble formation was observed and delivery was immediately terminated when a brisk shower of bubbles was detected.
Results: Transseptal puncture was performed at a typical location in all patients (atypical anatomy was not revealed by ICE). The microbubble effect was observed in all patients. In 1 patient the effect was observed despite a power reduction and the RF application had to be terminated. The following short (15-20 s) applications were performed with low RF energy. During the same procedure ICE imaging revealed 2 thrombi (2 and 5 mm) on the Lasso electrode. None of the patients experienced thromboembolic complications.
Conclusions: Intracardiac echocardiography is a useful imaging method in RF ablation. Low RF-energy and standard anticoagulation treatment do not prevent the microbubble effect and the formation of small thrombi.