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.

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Hepatic blood flow substantially reduces the size of the lesion produced by laser coagulation. Portal flow should therefore be occluded during laser treatment to produce lesions of clinically relevant dimensions.

Hepatic blood flow substantially reduces the size of the lesion produced by laser coagulation. Portal flow should therefore be occluded during laser treatment to produce lesions of clinically relevant dimensions.

Central venous catheters (CVC) are widely used in the United States and are associated with 250,000 to 500,000 CVC-related infections in hospitals annually. We used a catheter made from ultraviolet-C (UVC) transmissive material to test whether delivery of UVC from the lumen would allow inactivation of microorganisms on the outer surface of CVC. When the catheter was exposed to UVC irradiation from a cold cathode fluorescent lamp (CCFL) inside the catheter lumen at a radiant exposure of 3.6 mJ/cm 2 , more than 6-log 10 of drug-resistant Gram-positive bacteria adhered to the outer surface of the catheter were inactivated. Three to 7-log 10 of drugresistant Gram-negative bacteria and 2.8 log 10 of fungi were inactivated at a radiant exposure of 11 mJ/cm 2 . UVC irradiation also offered a highly selective inactivation of bacteria over keratinocytes under exactly comparable conditions. After 11 mJ/cm 2 UVC light had been delivered, over 6 log 10 of bacteria were inactivated while the viability loss of the keratinocytes was only about 57%.