Intramural haematoma should be referred to as thrombosed-type aortic dissection

OBJECTIVES: Intramural haematoma is defined pathologically as aortic dissection without an intimal tear. We therefore believe that this term is inappropriate as an acute clinical diagnosis, and instead, use the term 'thrombosed-type acute aortic dissection'. We compared the features of thrombosed-type acute aortic dissection with those of classic dissection. METHODS: Thrombosed type was defined as aortic dissection without flow in the false lumen of the aorta on contrast-enhanced computed tomography. Surgery was indicated for all cases of type A acute aortic dissection, and central repair operations were performed in 509 patients. We retrospectively studied these patients' surgical records. RESULTS: Three hundred and forty-four patients (68%) had classic dissection, and 165 (32%) had thrombosed type. Thrombosed type was associated with a significantly higher mean age (69 vs 60 years, P < 0.01), a higher incidence of cardiac tamponade (45 vs 28%, P < 0.01) and a lower incidence of malperfusion (6 vs 35%, P < 0.01) than classic dissection. Entry tears were located in the ascending aorta and the arch in 74 patients (45%) with thrombosed type. Since 2007, an intimal tear has been confirmed intraoperatively or on computed tomography in 39 (78%) of 50 patients with thrombosed-type aortic dissection. Mortality was significantly lower in patients with thrombosed-type dissection (6%) than in those with classic dissection (13%, P = 0.02). CONCLUSIONS: Most cases of intramural haematoma are acute aortic dissections with an intimal tear without re-entry. Intramural haematoma should be referred to as thrombosed-type acute aortic dissection. Thrombosed type can be easily diagnosed on contrast-enhanced computed tomography and has features distinct from those of classic dissection. Our classification may be useful for the diagnosis of these types of aortic dissection.