Intramural hemorrhage of the thoracic aorta. Diagnostic and therapeutic implications

Abstract

Background: Intramural hemorrhage (IMH) was recently identified at necropsy and anecdotally in vivo as a unique aortic syndrome (without entry and with no flap-like intraluminal component, such as overt aortic dissection). However, little is known about diagnosis, prognosis, and outcome of IMH.

Methods and results: Between 1983 and 1993, 360 patients from two medical centers with clinical indications of aortic dissection were prospectively evaluated; they presented to the emergency department a median of 3.5 hours after onset of back or chest pain or other suggestive symptoms. Among 195 patients with aortic syndromes, 25 patients (12.8%) were diagnosed to have IMH of the thoracic aorta with no evidence of a primary intimal tear, flap, or overt dissection by multiple noninvasive imaging modalities, including magnetic resonance imaging (n = 12), contrast-enhanced computed tomography (n = 14), and transesophageal echocardiography (n = 3) in random order. There were 16 men and 9 women with a median age of 56 +/- 13 years (range, 15 to 80 years). Arterial hypertension was present in the majority (84%), and Marfan's syndrome was present in 3 patients (12%). IMH was diagnosed within 4 days of hospital admission (median, 2.5 hours). IMH involved the ascending aorta (type A) in 12 cases (48%), the aortic arch in 2 (8%), and the descending aorta (type B) in 11 cases (44%); imaging results were validated by crossmatching with intraoperative, pathomorphological, and/or angiographic findings. IMH was 8.5 +/- 5 cm in length and 2.0 +/- 1.2 cm in aortic wall thickness. Aortic regurgitation and pericardial and mediastinal effusion were present in 5 of 12 patients (42%) with type A IMH and 2 of 11 patients (18%) with type B IMH. IMH progression to overt dissection, rupture, and/or acute tamponade occurred in 8 of 25 patients (32%) within 24 to 72 hours, indicating the need for urgent intervention. The 30-day mortality rate of IMH afflicting the ascending aorta was 80% (4 of 5 cases) with medical treatment (sedation and blood pressure control) versus no mortality in 7 cases with early surgical repair (P < .01); after 1 year, 71.4% of surgically treated patients were alive versus 20% in the medical group (P < .05). IMH of the aortic arch resulted in an early mortality of 50% (1 of 2 patients) with medical treatment. In IMH confined to the descending thoracic aorta, survival with medical treatment was not different from surgical therapy; there was 1 early death among 6 patients with medical therapy and none out of 5 patients with surgery (P = NS). At 1-year follow-up, medical and surgical therapy groups had survival rates of 80% and 83%, respectively (P = NS).

Conclusions: IMH is associated with a clinical profile and prognosis similar to classic dissection and may be considered an ominous precursor of overt aortic dissection. Tomographic noninvasive imaging ensures rapid, nontraumatic diagnosis of IMH. The outcome of IMH of the ascending aorta appears favorable only with immediate surgical repair.