Optimal timing of type A intramural hematoma repair

Acute type A aortic intramural hematomas (IMHs) are often included under the spectrum of acute aortic syndromes. The classical definition is the presence of hematoma in the media without identifiable intimal tear. Dissection occurring within two weeks of presentation is defined as acute. Acute type A IMH remains a subject of debate, especially regarding its definition and management. The classical theory of pathogenesis of IMHs is ruptured vasa vasorum in the aortic media. However, the majority of IMHs are now detected with an intimal defect using high-resolution computed tomography and intravascular ultrasound, which implies that IMHs may be a subset of aortic dissections (ADs), with very limited flow in the false lumen. Much controversy remains regarding IMH differences in presentation, diagnosis, and risk for progression. Geographic location and ethnicity, especially Asian vs. Western, possibly affect the natural history and outcomes of acute type A IMH. In this review, we describe the pathophysiology and management strategies for acute type A IMHs.