Chapter 2

Pathophysiology and Risk Factors of Type A Acute Aortic Dissection

Yi-Heng Li and Chwan-Yau Luo

Abstract

Acute aortic dissection is life-threatening. The pathophysiology of aortic dissection usually starts from an intimal tear with subsequent penetration of blood through the aortic media layer. Sometimes, a spontaneous hemorrhage of the vasa vasorum within the aortic wall will cause an aortic intramural hematoma to form, which will initiate aortic dissection. Blood in the aortic wall results in a dissection plane within the media and creates a false lumen, which may propagate antegradely or retrogradely along the aorta. Aortic media degeneration and cystic medial necrosis are common findings in aortic dissection. In addition to aortic medial abnormalities, there are several risk factors that are associated with acute aortic dissection. Hypertension is the most common prevalent risk factor. Recent studies have found that several mutations involving genes encoding for components of extracellular matrix and smooth muscle cell proteins are responsible for aortic dissection in Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, and familial thoracic aortic aneurysm and dissection. Congenital aortic diseases, such as coarctation of the aorta or bicuspid aortic valve are important risk factors for aortic dissection. Other acquired conditions, such as aortitis, pregnancy, drug abuse, trauma, and some medical and surgical procedures are also related to aortic dissection. This chapter makes an extensive review of the current knowledge about the pathophysiology of acute aortic dissection. The known risk factors that contribute to the occurrence of aortic dissection will be discussed.

Total Pages: 31-50 (20)

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