Clinical Investigations Spontaneous Echocardiographic Contrast in Descending Aorta in Patients Without Aortic Dissection and Associated Clinical and Echocardiographic Characteristics

Spontaneous echo contrast (SEC) is found in the thoracic aorta in association with dissection. But SEC in the descending aorta (DA) in the absence of aortic dissection has been rarely reported, and data concerning flow dependence of SEC formation in the DA is less c lear than that in the intracardiac location. The purposes of this study are to evaluate both the frequency and elinical significance of SEC in the DA in the absence of aortic dissection, and to investigate the hemodynamic correlates of SEC in the DA. The study group comprised 1 199 consecutive pts (m ale 321, female 878, mean age 47.2±21.5) who underwent transesophageal echocardiography (TEE) at our institution. Cardiac rhythm w as atrial fibrillation in 495 ( 41. 3 %) pts. Peak flow velocities (pFV, cm/see) in the DA were measured between 90 and 130 degrees with HPRF Doppler interrogation during TEE, and maximal shear ra te (SR, s-J) in the DA w as calcu lated. Spontaneous echo contrast in the DA was detected in 54 (4.5 %) of pts. Between subgroups with and without SEC in the DA, age (60.6 ± 8 vs 40.6 ± 14.2, p=O.OOOI ), male gender (66.7 % vs 43.9 %, p=O.OOI), diameters (cm) of ascending aorta (AA, 4.2 ± 1.0 vs 3.3 ± 1.1 , p=O.OOO), and DA (0.06 ± 0.9 vs 2.1 ± 0.4, p=O.OOOI ), frequency of left ventricular dysfunction (LVD, 7.4 % vs 2. I %, p<0.05), severe aortic regurgitation (0 vs 3.5 %, p<0.05), aortic wall calcification (9.3 % vs 0.5 %, p=O.OOOO), complex plaque in the DA (13 % vs 0.7 %, p=O.OOOI), nondissecting aneurysms (3 1.5 % vs 4 %, p=0.00001), pFV (38 ± 9 cm/s vs 5 1±21 c m/s, p<0.00001) and maximal SR in the DA (51±29 s-1 vs 105 ± 47 s-1, p<0.00001) were significantly different. But SEC in the DA was not found to be associated with cardiac rhythın, mitral disease, intracardiac SEC and/or thrombus and embolic event (p>0.05). Multiple regression analysis confirmed that SR, diameter of DA, aortic wall calcification, complex plaque in the DA, severe aortic regurgitation and male gender were independent variabtes associated with SEC in the DA. We conclude that (1) presence of SEC in the DA seems to be associated with larger aortic diameters, male gender, older age, atherosclerosis . L VD, absence of aortic regurgitation, relatively lower pFV and SR in the DA, (2) results appear to confirın that formati on of SEC in the DA is a local flowdependent phenomenon as those in intracardiac chambers, (3) although our results did not confirm a relationship between SEC in the DA and embolic events, further studies are needed.