Intracardiac echocardiography. Experimental observations on intracavitary imaging of cardiac structures with 20-MHz ultrasound catheters.

Recently catheter-based ultrasound devices have become available for obtaining high-resolution images of blood vessels. In this study we evaluated the feasibility of imaging cardiac structures using 20-MHz ultrasound catheters. In 25 dogs, the ultrasound catheter was advanced into the right and left heart chambers percutaneously. The intravascular devices yielded images of the right atrial wall, right and left ventricular myocardia, tricuspid, pulmonic, and aortic valves, and the great vessels. Although the small depth of field inherent to the frequency range of 20 MHz limited the visualization to only portions of the cardiac chambers, the images obtained were of high resolution and allowed easy identification of the various cardiac structures. Intracardiac echocardiography was easy to perform and did not result in damage to the cardiac structures. We conclude that intracardiac echocardiography using ultrasound catheters provides a new approach to cardiac imaging and that the development of lower frequency catheters could aid in extending the potential utility of intracardiac echocardiography.