Direct in vivo visualization of right cardiac anatomy by fibreoptic endoscopy: observation of radiofrequency-induced acute lesions around the ostium of the coronary sinus.

Current mapping techniques used during electrophysiological study involve catheter placement under fluoroscopic guidance and are associated with prolonged radiation exposure. We considered that direct visualization of right heart anatomy by means of fibreoptic endoscopy could be useful in accurately localizing and guiding the ablation of arrhythmogenic substrates. Our goal was to evaluate the ability of this device to safely and accurately visualize the ostium of the coronary sinus and its vicinity as well as radiofrequency-induced acute lesions. Anaesthetized dogs (n = 4) were studied. Multipolar electrode catheters and a 3.6 mm diameter fibreoptic endoscope with a latex balloon covering the distal tip were inserted into the right atrium. The blood pressure, and surface and intracardiac electrocardiograms were recorded simultaneously. Radiofrequency energy was delivered just inside the coronary sinus ostium or in its vicinity. The acute lesions were carefully observed by endoscopy. Postmortem examination was then performed. With a balloon volume of 7-10 ml, the visual field was 15-20 mm in diameter. The blood pressure was generally stable. The ostium of the coronary sinus and its vicinity were clearly and accurately identified, and catheter placement in the coronary sinus and its vicinity could be achieved under direct vision in all four dogs. Additionally, the process by which acute lesions were created by radiofrequency was also directly visualized in great detail. There was a good concordance between endoscopically observed images and postmortem findings, and there was a strong correlation between delivered energy and the volume of the radiofrequency-induced lesions (r = 0.895).(ABSTRACT TRUNCATED AT 250 WORDS)