Aortic Aneurysm Prevention
In connection with aortic aneurysm and ultrasound, prevention is centered on predicting when a patient crosses over the risk stratification for rupture.
Once the aorta aneurysm diameter approaches 6 cm, the aorta loses elasticity to the point that any increases in blood pressure, e.g., exercise, could easily exceed the maximum containment of the weakened wall, causing rupture. In the abdominal aorta, the critical diameter for surgical prevention of rupture is when it exceeds 5.5 cm or when the diameter has reached an expansion rate of greater than a half-centimeter a year. This is determined via ultrasound or CT scan. Such a measurement (or less, when the aneurysm is symptomatic), calls for repair. At this diameter, the risk of the surgery becomes less than the risk of having a pre-ruptured aneurysm. In the thoracic aorta, like that of abdominal aortic aneurysms, the risk of rupture exceeds the risks in surgical repair once the diameter exceeds 5.5 cm or when the expansion rate exceeds 1 cm/year. CT or MRI are used if time and urgency allow.
Dissection is a feature associated with aortic aneurysm in which the layers of the aortic wall separate due to the extravasation of blood from a tear in the inner aortic layer (the “intima”). This will affect, diminish, or even obliterate arterial blood flow in the branching arterial supply involved at the dissecting segment. Distal organs to this development are at risk for ischemia and necrosis. Prevention of ischemia due to this compromise in perfusion is addressed via surgery.