Two dimensional arrays for real time intracardiac volumetric imaging
We describe the design, fabrication, and evaluation of catheter mounted two dimensional array transducers for real time intracardiac volumetric scanning as a guide for cardiac interventional procedures including electrophysiological mapping and radiofrequency ablation. The matrix arrays are built on multilayer polyimide flex circuits in catheters 2.6 mm in diameter. They include 10×10 = 100 elements operating at 5 MHz and 7 MHz in both side scanning and forward viewing designs with integrated EKG ring electrodes for myocardial mapping. The Duke University real time 3D system produced 65 degree pyramidal scans with selectable image planes at any desired angle and depth. Images in tissue phantoms showed axial resolution of 1 mm and lateral resolution of 1 mm at a depth of 1 cm. In studies of in vivo sheep, catheter transducers within the cardiac chambers imaged tricuspid and mitral valves, septum and ventricular walls with good penetration to depths of 6 cm. EKG electrodes in the catheter produced simultaneous electrograms from the ventricular wall.