ABSTRACT
Electrical isolation of the pulmonary veins (PVs) can be curative in certain patients with atrial fibrillation. The ability of a diode laser balloon ablation catheter to isolate PVs was assessed in an open-thoracotomy caprine model system. After a median sternotomy, the left atrial appendage was cannulated in 19 goats. A laser balloon catheter was placed at the PV ostia and used to deliver photonic energy to the periostial tissue. The applications were delivered at 3.7, 4.5, or 5.4 W/cm for 90-150 seconds. Electrical continuity of the PV with the left atrium was assessed using a multielectrode mapping catheter. After a single application of photonic energy, electrical isolation of the PVs was achieved in (70%) 19/27 PVs. However, the success of electrical PV isolation did not correlate with the dose or duration of the applications. When reflectance spectroscopy was utilized to ensure adequate orientation and contact of the laser balloon catheter with the left atrial myocardium, complete PV isolation was achieved in 5/5 veins at 3.5 W/cm for 120 seconds. Pathological examination revealed no PV stenosis, no pericardial damage, minor lung lesions without pleural perforation, minimal endothelial disruption, and, in the presence of adequate heparinization, no endocardial charring or overlying thrombus. Effective isolation of the PVs can be achieved by delivery of a continuous circular beam of photonic energy to ablate the left atrial - pulmonary venous junction. The use of reflectance spectroscopy to provide real-time monitoring of the blanching effect of balloon-tissue contact optimizes lesion delivery.
