Although hypertension, hyperlipidemia, and smoking are considered risk factors for the expansion of aneurysms, only smoking has been identified as a consistent risk factor; smoking increases the growth rate by 20–25%. Data from a study by Brady et al. including 1743 patients followed prospectively indicated that blood pressure and cholesterol levels did not predict the rate of expansion; aneurysms expanded significantly faster in current smokers than in former smokers. In addition, other studies indicated that the risk of rupture and the risk of death due to rupture are higher among current smokers than among former smokers and patients who never smoked by as much as a factor of 14 for smokers.
Weakening of arteries may occur because of loss of elasticity of the aortic wall due to aging. Another disease that affects the aortic wall is cystic medial necrosis, and this appears histologically as smooth muscle cell necrosis and degeneration of elastic layers within the media. The cause of the disease is unknown and mostly affects the thoracic aorta. Virtually all patients with Marfan syndrome develop cystic medial necrosis disease and many, at a young age, develop aneurysms that occur mainly in the ascending aorta, where the aorta originates from the heart.

Страницы: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9