Acute Aortic Syndromes

Abstract

physician to King George II, first described on necropsy an acute aortic dissection.Over the course of more than 200 years, we have developed a growing awareness and understanding of acute and chronic aortic syndromes.Recent advances in imaging and therapeutic techniques have further emphasized the importance of early diagnosis of acute aortic syndromes, which continues to be crucial to survival.However, we continue to be uncomfortable in the diagnosis and management of this highly lethal disorder.In the present report, we review the etiology, pathophysiology, clinical presentation, outcomes, and therapeutic approaches to acute aortic syndromes.In each section, we summarize the most clinically relevant issues as "take home points" (THPs) to affirm their importance in the diagnosis and management of this disorder. PathophysiologyAcute aortic syndrome is the modern term that includes aortic dissection, intramural hematoma (IMH), and symptomatic aortic ulcer.In the classic sense, acute aortic dissection requires a tear in the aortic intima that commonly is preceded by medial wall degeneration or cystic media necrosis.1 Blood passes through the tear separating the intima from the media or adventitia, creating a false lumen.Propagation of the dissection can proceed in anterograde or retrograde fashion from the initial tear involving side branches and causing complications such as malperfusion syndromes, tamponade, or aortic valve insufficiency.[2][3][4][5] Both acquired and genetic conditions share a common pathway leading to the breakdown in the integrity of the intima.All mechanisms that weaken the media layers of the aorta will eventually lead to higher wall stress, which can induce aortic dilatation and aneurysm formation, eventually resulting in intramural hemorrhage, aortic dissection, or rupture.The factors culminating in a clinical dissection are quite diverse.The most common risk condition for aortic dissection is hypertension, with chronic exposure of the aorta to high pressures leading to intimal thickening, fibrosis, calcification, and extracellular fatty acid deposition.Furthermore, the extracellular matrix may undergo accelerated degradation, apoptosis, and elastolysis with eventual intimal disruption, most often at the edges of plaques.1,6 -8 Marfan's syndrome, vascular Ehlers-Danlos syndrome, annuloaortic ectasia, bicuspid aortic valve, and familial aortic dissection are genetic conditions that often cause acute aortic syndromes.A common denominator to these different genetic disorders is a similar pathophysiology that includes a dedifferentiation of vascular smooth muscle cells and enhanced elastolysis of aortic wall components, leading to a compromised intima and aortic dissection.9 Given this genetic predisposition, a detailed family history in patients diagnosed with acute aortic syndromes or sudden death is particularly important in assessing the need for family screening.