Nonfluoroscopic transseptal catheterization: safety and efficacy of intracardiac echocardiographic guidance.

INTRODUCTION: Recently, there has been a revival in the use of transseptal catheterization due to the development of balloon mitral valvuloplasty and radiofrequency catheter ablation. Complications of transseptal puncture, although rare, can be serious and life-threatening. In the present study, we evaluated the use of intracardiac echocardiography (ICE) as the sole imaging modality to guide transseptal puncture and catheterization. METHODS AND RESULTS: In each animal, 10 transseptal punctures were performed guided solely by ICE. The standard approach to transseptal catheterization using a Brockenbrough needle and long vascular sheath was used except for the use of ICE instead of fluoroscopy. A 6.2-French/12.5-MHz and 9-French/9-MHz ICE catheter was used for imaging. At the end of each study, pathologic evaluation was performed. Transseptal puncture was performed safely, guided solely by ICE, in each of 100 attempts (five attempts guided by each ICE catheter in 10 dogs). While the fossa ovalis was easily visualized with both ICE catheters, the 9-French/9-MHz catheter offered an enhanced field of view. On pathologic evaluation, there was no evidence of perforation of either the right or left atrium outside of the fossa ovalis. CONCLUSION: Both ICE catheters used in this trial allowed for excellent visualization of the fossa ovalis and safe transseptal puncture. Intracardiac echocardiography may be a better imaging modality than fluoroscopy for guiding transseptal catheterization, especially in less experienced hands.

Technical aspects of ultrasound imaging guidewires.

In many interventional catheterization laboratories around the world the use of intravascular ultrasound (IVUS) has become a routine addition to the catheter-based interventional procedures. IVUS catheters, for coronary use, typically of a size around 3 French, provide images that assist in diagnosing the coronary obstructive disease, choosing the most appropriate recanalization method, monitoring the recanalization process and evaluating the end result. The downside of the use of IVUS, apart from additional cost to the procedure, is the additional exchange of catheters during the procedure. Several designs of hybrid catheters have been proposed, combining IVUS imaging with a therapeutic de-obstruction method in one catheter. A more modular approach is to equip the guidewire with imaging capability. Such a guidewire would provide an image of the stenotic region as well as guide the recanalization catheter to its location. It will, however, require further miniaturization of the ultrasound imaging technology, which already is scaled down considerably to enable coronary imaging. In addition, the ultrasound imaging guidewire (UIG) would have to possess specific qualities in bending and torque to act as a true guidewire. A first step to modularity is the separately used 'imaging core', which is advanced into the guidewire lumen of a therapeutic catheter, but cannot guide this catheter to the desired location. The combination of both imaging and mechanical requirements would yield a true UIG, but constitutes major technical challenges.