The transponder system: a new method of precise catheter placement in the right atrium under echocardiographic guidance.

The ability to localize catheters within the heart has gained importance with the use of percutaneous catheter ablation and the transseptal approach for valvuloplasty. A prototype interactive transponder catheter system, specifically designed to mark the catheter tip for echocardiographic visualization, was used to place catheters at the tricuspid anulus and the fossa ovalis in anesthetized dogs. Catheter tip location was marked by lesions produced by radiofrequency energy delivered at the distal catheter electrode. At autopsy, the center of the radiofrequency-induced lesion was located 2.8 +/- 0.7 mm from the edge of the lateral tricuspid anulus and 3.5 +/- 3.1 mm from the center of the fossa ovalis. The transponder catheter system offers the ability to precisely position catheters in the right atrium under echocardiographic guidance.