760-6 Initial In-Vivo and In-Vitro Testing of an Ultrasound-Guided Directional Coronary Atherectomy Catheter

Abstract

We report the results of initial in-vitro and in-vivo testing of a new, ultrasoundguided directional coronary atherectomy (GDCA) catheter (DVI, Redwood City, CA) which is being developed as a potential first-generation clinical product. A 30 MHz, focused transducer is incorporated in the body of the rotating cutter. Because of the relatively large aperture of the transducer (0.040”). resolution and penetration are superior to stand-alone IVUS catheters. In order to provide maximum rotational stability for imaging, a fixed-wire catheter configuration has been selected for initial production. The GTOTM shaft design has been adopted for torque control. 11 GDCA catheters, 8 with standard (3.25 mm) balloons and 3 with graft (4.5 mm) balloons, were tested in 4 normal farm pigs and 3 pigs with injury models of coronary stenosis. All catheters were able to be selectively directed into the target vesseil/lesion with good torque control. High resolution of the images allowed the clear demonstration of intima, venous structures, pericardium and myocardium. With balloon inflations the adequacy of engagement of the arterial wall by the cutter was directly visualized. In vitro testing using fresh porcine aorta compared the cutting ability of the combined device to the standard GTO. The weights of single cuts were not significantly different at 10 psi (5.8 mg vs 6.2 mg). and 30 psi (7.9 mg vs 8.1 mg). To fill the nose cone of the GDCA 6.4 cuts were required compared to 5.8 for the GTO (p =p ns). The weights of tissue from the filled nose cones were not significantly different (26.5 gm vs 20.5 gm). High resolution ultrasound imaging has been combined with a directional atherectomy catheter in a configuration suitable for clinical trials.