Pathologic Characteristics and Surgical Indications of Superacute Type A Intramural Hematoma

Background The treatment policy for acute intramural hematoma involving the ascending aorta remains controversial. Methods This study compared the pathologic characteristics of intramural hematoma with those of acute aortic dissection with a false lumen. The study group comprised 69 patients with intramural hematoma and 156 with acute aortic dissection who underwent emergency operation between 1995 and 2003. Results Patients were significantly older in the intramural hematoma group than in the dissection group (67.7 ± 7.2 years compared with 59.8 ± 11.6 years; p< 0.0001). Pericardial hemorrhage was present in a higher proportion of patients in the intramural hematoma group than in the dissection group (66.7% compared with 50.6%; p = 0.0257). Three patients (4.3%) died in the intramural hematoma group, whereas 26 patients (16.7%) died in the dissection group (p = 0.011). Histopathologic examination showed no difference in the severity of medial changes, but the site of dissection differed. The thickness of the residual media of the adventitia side was 0.21 ± 0.12 mm in the intramural hematoma group compared with 0.32 ± 0.22 mm in the acute aortic dissection group. Dissection was significantly nearer the adventitia in the intramural hematoma group (p = 0.0016). Conclusions Dissection is nearer the adventitia in intramural hematoma than in dissection, leading to a greater probability of rupture. These results suggest that operation as soon as possible after the onset of intramural hematoma will contribute to improved survival.