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Hypertension in the Patient with Aortic Dissection
Questions
1
What are the acute aortic syndromes?
Acute aortic syndromes (AAS) are a group of emergent aortic pathologies with similar clinical characteristics. AAS occur when blood penetrates the medial layer of the aorta either from a tear or ulceration of the intima or rupture of the vessels within the media. These syndromes include aortic dissection (AoD), penetrating atherosclerotic ulcer (PAU), and intramural hematoma (IMH). AoD is a tear within the ascending or descending aorta that allows blood to separate the medial layer from either the intima or external layers, creating a false lumen within the aortic wall. PAU is the erosion of the wall of the intima causing bleeding into the media and aneurysm formation. IMH occurs when there is bleeding in the aortic wall due to rupture of the vessels within the media (vasa vasorum) or via an undetectable intimal tear. In contrast to AoD, a false lumen is not created in PAU and IMH. In both PAU and IMH, bleeding can extend within the media and lead to AoD or aortic free-wall rupture.
2
What are the risk factors for AAS?
Risk factors for AAS include aortic abnormalities (e.g., aneurysm) and increased aortic wall stress, most commonly secondary to trauma or hypertension. Other acquired causes of AAS are pregnancy, inflammatory aortitis, and cocaine or other stimulant use. Aortic and valvular pathology related to congenital abnormalities and genetic diseases (syndromic and nonsyndromic) are more commonly seen in younger patients under 40 years old and are associated with increased risk of AoD or rupture ( Table 26.1 ). Patients of 40 years or older are more likely to have hypertension as the primary risk factor for AAS. Atherosclerosis does not appear to be an independent risk factor for AoD.
Table 26.1
Risk Factors for Developing Acute Aortic Syndromes
Modified from Hiratzka LF, Bakris GL, Beckman JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation. 2010;121(13):e266-369.
| Acquired |
| Hypertension |
| Trauma |
| Pregnancy |
| Inflammatory aortitis |
| Cocaine or methamphetamine use |
| Genetic Diseases |
| Bicuspid aortic valve |
| Marfan syndrome |
| Turner syndrome |
| Ehlers-Danlos syndrome |
| Loeys-Dietz syndrome |
| Familial thoracic aortic aneurysm and dissection syndrome |
| Other mutations in genes (e.g., fibrillin, tumor growth factor-beta receptor, SMAD3, myosin heavy chain) |
3
What are typical presenting symptoms for the patient with an acute AoD?
AAS typically cause acute, severe chest and/or back pain generally localized to the location of aortic injury. Radiating or changing pain may indicate progression to other areas of the aorta. AAS are potentially fatal and should be considered in the initial evaluation of chest pain in addition to acute coronary syndrome, pulmonary embolism, pneumothorax, and esophageal perforation.
4
How should blood pressure be assessed in the patient with an AAS?
A thorough vascular examination may detect absent or diminished pulses, which can indicate a severely affected artery. Blood pressure (BP) should be measured in all extremities to determine highest central BP, which should then be used to target therapy. Pulse pressure on presentation has prognostic value. In patients with Type A AoD, a narrow pulse pressure (<40 mm Hg) indicates increased risk of intrathoracic complications, such as periaortic hematoma and cardiac tamponade, whereas elevated pulse pressure (>75 mm Hg) is associated with extension into the abdominal aorta.
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