Intracavitary ultrasound was first applied for viewing the results of coronary and other vessel angioplasty. The device is a 20-MHz rotational array mounted on a catheter and introduced into a vascular segment to determine the morphology of the artery wall. It is also useful to assess stent apposition and extravascular pathology.
Intracardiac ultrasound uses a miniaturized phased-array 8-10 MHz probe mounted on a catheter. During transseptal ASD closure, it verifies adequate deployment and closure of the closure device. In electrophysiologic procedures, it is used to identify intracardiac anatomic landmarks, verify catheter position, and monitor lesion progression and thrombus formation. In this figure, the catheter tip can be angled over 90 degrees from normal, giving orthogonal views of the interatrial septum during procedures.
New Windows from Inside the Heart
The ultrasound catheter is easy to maneuver and gives unique view planes inside the heart that are not possible with surface echo or TEE due to depth of field or inaccessibility. Procedures in the ostia of the pulmonary veins or atrial appendages can now be performed under direct US observation in (local) sagittal or transverse views. This diagram shows the idealized view from the posterior RA/SVC junction into the right superior pulmonary vein.
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