Electrical superior vena cava isolation using photodynamic therapy in a canine model.

With the new era of multi-tip radiofrequency or balloon ablation catheters replacing the point-to-point ablation strategy, we aimed to determine the feasibility of a ring-laser catheter ablation technology to electrically isolate the superior vena cava (SVC) by exploring the advantages of the limitless catheter tip size possibly with the photodynamic therapy (PDT)-mediated ablation. We developed a first-generation prototype of a circular-laser-mapping catheter by fitting a 7 cm plastic optical fibre onto a circular variable-loop Lasso (TM) mapping catheter. Following SVC venography, both the laser catheter and another ring catheter for monitoring the SVC potentials were placed at the SVC. After the systemic infusion of a photosensitizer (talaporfin sodium), we initiated the irradiation with an output of 1 W in three canines and 0.3 W in four. The creation of electrical isolation as well as occurrence of phrenic nerve injury, sinus node injury, and SVC stenosis were evaluated before, immediately after, and 1 month after the procedure. A PDT-mediated SVC isolation was successfully performed in all seven canines. The isolation was completed with a laser irradiation of 70.4 +/- 71.4 J/cm under 30.9 +/- 5.0 A mu g/mL of a photosensitizer without any sinus node injury, phrenic nerve palsy, or SVC stenosis in both the acute and chronic evaluations. The minimum isolation time of 270 s was not correlated with the laser input power or the photosensitizer concentration. The electrical SVC isolation was successfully and instantly achieved using the PDT laser-ring catheter without any complications.