Transvenous intracardiac echocardiography.

A specially designed ultrasonic transducer, 0.2 mm in length and 0.75 mm in diameter, operating at 7.5 megahertz and mounted on a thin flexible coaxial cable was advanced to the distal tip of a right heart or transseptal catheter in 20 patients during cardiac catheterization. Left atrial, aortic root and right atrial cavity size, pulmonary arterial diameter at various sites, right ventricular wall thickness and the width of a pericardial effusion were demonstrated. Tricuspid, pulmonary, and aortic valves were seen and their motion displayed. With the transducer positioned at the tip of a transseptal needle it could be recognized when it made contact with the interatrial septum. Puncture into the left atrium, avoiding such structures as the aorta, was facilitated in this fashion. No complications were encountered in any patient. Intracardiac echocardiography appears to be a safe, valuable adjunct to both conventional echocardiography and cardiac catheterization. Furthermore, recordings of structures that may be difficult or impossible to obtain with routine external echocardiography may be made possible.