[Two-dimensional echo-Doppler technic for evaluating dissecting aneurysms using the paravertebral approach].

Abstract

Cross-sectional echocardiography facilitates recognizing dissecting aortic aneurysms, but the diagnosis of abnormalities of the descending aorta in the retrocardiac portion is difficult. We prospectively designed to assess the usefulness of a new echocardiographic technique in defining the retrocardiac descending thoracic aorta in its long and short axes. Two patients with dissecting aneurysms involving the retrocardiac descending aorta were studied in the 90 degrees right lateral position using a Toshiba SSH-11A or SSH-40A cross-sectional echocardiographic apparatus. The transducer was positioned in the third or fourth intercostal space closely to the left of the thoracic vertebrae, and the ultrasonic beam was directed toward the retrocardiac descending aorta from the patient's back. The descending thoracic aorta was identified in its long axis as a straight tubular structure with parallel walls. The transducer was then rotated approximately 90 degrees, to visualize the descending aorta in its short axis as a circular structure. This "paravertebral approach" has not previously been reported. In both patients, the retrocardiac descending thoracic aorta was clearly visualized in its long and short axes, and the oscillating intimal flap was visualized within the descending aorta in the paravertebral approach. Pulsed Doppler echocardiography (PDE) using the long-axis paravertebral approach identified the flow in the false and true lumens of the descending thoracic aorta. Flow patterns including the peak flow velocity and the velocity profile obviously varied between the true and false lumens. The peak flow velocities in the former were extremely high compared to those in the latter. The former exhibited laminar profiles, but the latter showed some spectral broadening. By the same approach, the entrance tear was explored and the jet flow through the tear was detected in Case 1 by PDE, which had high flow velocity with wide spectral broadening and aliasing in systole and also had relatively low flow velocity with some spectral broadening in diastole. To our knowledge, there has been no previous report of detecting flow at the entrance tear by PDE. These cross-sectional echocardiographic studies suggest that the paravertebral approach may prove helpful in initially evaluating patients with symptoms or signs suggestive of acute dissecting aneurysms. However, comprehensive studies are necessary to define the sensitivity and specificity of these echocardiographic techniques in recognizing all types of dissecting aneurysms.