Full-color direct visualization of the atrial septum to guide transseptal puncture.

INTRODUCTION: Transseptal puncture is required for many interventional procedures but has a serious complication rate of approximately 1%-primarily related to misidentification of the fossa ovalis resulting in inadvertent puncture of other cardiac structures. We investigated the utility of a full color visualization catheter to correctly position and guide transseptal puncture of the fossa ovalis. METHODS AND RESULTS: Transseptal puncture and left atrial cannulation were performed after visualization of the atrial septum and fossa ovalis with the visualization catheter (IRIS, Voyage Medical Inc.) on six swine. For each animal, the transseptal puncture was performed twice and the catheter was examined for clot after each puncture. The 12 transseptal punctures required 6.8 +/- 3.6 minutes procedural time and 300 +/- 94 mL of fluid administered per procedure (i.e., two punctures). IRIS visualization of the atrial septum correlated well with postmortem examination of the atrial septum. In the three animals in which a patent foramen ovale was present (as confirmed by pathological examination), it was also correctly identified by in vivo visualization using the IRIS catheter. CONCLUSION: The IRIS catheter allows direct in vivo visualization of the interatrial septum to guide transseptal puncture of previous punctures.

Temporary occlusion of the great cardiac vein and coronary sinus to facilitate radiofrequency catheter ablation of the mitral isthmus.

INTRODUCTION: Ablation of the mitral isthmus to achieve bidirectional conduction block is technically challenging, and incomplete block slows isthmus conduction and is often proarrhythmic. The presence of the blood pool in the coronary venous system may act as a heat-sink, thereby attenuating transmural RF lesion formation. This porcine study tested the hypothesis that elimination of this heat-sink effect by complete air occlusion of the coronary sinus (CS) would facilitate transmural endocardial ablation at the mitral isthmus. METHODS: This study was performed in nine pigs using a 30 mm-long prototype linear CS balloon catheter able to occlude and displace the blood within the CS (the balloon was inflated with approximately 5 cc of air). Using a 3.5 mm irrigated catheter (35 W, 30 cc/min, 1 minute lesions), two sets of mitral isthmus ablation lines were placed per animal: one with the balloon deflated (CS open) and one inflated (CS Occluded). After ablation, gross pathological analysis of the linear lesions was performed. RESULTS: A total of 17 ablation lines were placed: 7 with CS Occlusion, and 10 without occlusion. Despite similar biophysical characteristics of the individual lesions, lesion transmurality was consistently noted only when using the air-filled CS balloon. CONCLUSIONS: Temporary displacement of the venous blood pool using an air-filled CS balloon permits transmurality of mitral isthmus ablation; this may obviate the need for ablation within the CS to achieve bidirectional mitral isthmus conduction.