Different remodeling of descending thoracic aorta after acute event in aortic intramural hemorrhage versus aortic dissection

The natural healing process of medically treated aortic dissection (AD) and aortic intramural hemorrhage (AIH) developed in the descending thoracic aorta was compared to test the hypothesis that absence of intimal tear and flow communication in AIH may have different impact on the remodeling of the affected aorta after the acute event. In 25 patients with AD and 20 with AIH involving distal descending thoracic aorta stabilized with medical treatment, follow-up (mean 9 months) transesophageal echocardiography was performed to measure the maximal dimensions of aorta, true lumen, false lumen in AD, and abnormal wall thickening in AIH. The sex ratio, prevalence of hypertension, baseline maximal dimension, and longitudinal extent of the affected aorta did not show any significant difference in both groups. Patients with AIH were older than those with AD (63 ±10 vs 50 ± 9, p <0.01). Disappearance of abnormal wall thickening with complete restoration of the aorta occurred in 70% (14 of 20) patients with AIH, which was significantly more frequent than in AD (8%, p <0.01). In AD, progressive dilatation of the aorta with continuous flow communication in the false lumen resulted in larger dimension of the aorta than in AIH (44 ±13 vs 35 ± 7 mm, p <0.01). Absence of persistent flow communication resulted in a favorable remodeling process in AIH affecting distal descending aorta. This finding, along with different mean age in AIH and AD, may suggest that AIH is not just a precursor of overt AD but a distinct disease entity with different pathophysiology.