INTRACARDIAC ULTRASOUND IMAGING DURING TRANSSEPTAL CATHETERIZATION

Study objective: The purpose of this study was to assess the feasibili ty of using small 12.5- or 20-MHz intracardiac ultrasound catheters to image the fossa ovalis and guide transseptal catheterization. Design: The study was performed in three phases. First, in vitro imaging of h uman autopsy hearts was performed to define the intracardiac ultrasoun d appearance of the fossa ovalis and transseptal apparatus. Subsequent ly, the optimum approach for imaging the fossa ovalis in vivo was esta blished in 30 patients. Finally, intracardiac ultrasound imaging was p erformed during transseptal catheterization of 10 patients undergoing percutaneous mitral commissurotomy. Interventions: Intracardiac ultras ound imaging was performed with a 12.5- or 20-MHz single-element mecha nical device in which a central imaging core is rotated within a 6F po lyethylene sheath. Measurements and results: In both in vitro and in v ivo studies, the fossa ovalis was easily identifiable as a thin membra nous region surrounded by the thicker muscular portion of the interatr ial septum. Initial in vivo studies established venous access by the f emoral route to be superior to the internal jugular approach for cathe ter introduction. Studies performed during transseptal catheterization established the utility of using the fluoroscopic image of the cathet er adjacent to the fossa ovalis to generate a guiding shot for positio ning the transseptal apparatus. In addition, distention of the fossa p rior to needle perforation could be demonstrated. However, since it wa s often difficult to track the tip of the needle, actual puncture of t he fossa was rarely demonstrated. Conclusions: Intravascular ultrasoun d imaging can precisely locate the fossa ovalis in virtually all subje cts. It therefore may assist transseptal catheterization.