The aorta is the mahin supplier of fresh blood in the human body. The enlargement of an aorta by 1.5 times the normal size is referred to as aortic aneurysm. This is a serious condition because the aorta may rupture causing severe internal bleeding and death. As the size of aneurysm increases, the risk of aorta rupture increases. Aortic ruptures are one of the most common causes of death in the western world. When there is a bulge in aorta near the heart, the condition is called as ascending aortic aneurysm. Aneurysms of the ascending aorta form a major percentage of all thoracic aneurysms.
The average annual growth rates of ascending aortic aneurysm vary from 1-4 millimeters. But patients with Marfan’s syndrome or bicuspid valves experience much higher growth rates. Moreover, if a person has a large aneurysm then the growth rate is likely to be higher. Surgical treatment is dependent on two variables: progression of the aortic diameter and the causes of aneurism. For instance: surgery in the ascending aorta is performed for smaller size aneurysms than in the descending aorta.
For most patients, the first symptom is likely to be death. This lack of symptoms in aortic aneurysm coupled with little or no success in drug therapy makes size the most important criterion for surgical intervention. However, symptomatic patients should be operated irrespective of size because failure to do so can prove fatal.
A major challenge in determining the Ascending Aortic Aneurysm Size Criteria is measuring the aortic diameter. The growth of aneursymal aorta is very slow, as low as 1mm per year. Moreover, there is no consensus on whether the aortic wall must be included in the aortic diameter. Hence, comparisons with the original or previous images can be difficult. The incidence of rupture, dissection or death increases proportionately as the aorta grows, culminating at an aortic size of 6 centimeters.
Most medical associations have issued guidelines regarding when surgery should be performed for aortic aneurysm. One golden rule is that if aneurysm increases by 0.4 centimeters in any one year then surgery must be performed. For patients with Marfan syndrome, SFC of France recommends surgery when aneurysm is more than 5 centimeters, while the ACC of America and ESC of Europe suggest surgery when aortic aneurysm is more than 4.5 centimeters. For normal patients, surgery is advised only when the aortic enlargement is more than 5 centimeters. According to SFC of France, this measurement has to be indexed to Body Mass Index (BMI) of the patient. A large number of patients have been operated successfully despite their aortic diameter being lesser than 5.5 centimeters.
A pertinent question to ask would be: Can one set of criteria for surgical intervention apply to all individuals, irrespective of BMI. The answer is that for very large or very small individuals it is important to make body size corrections. The availability of rich data has helped doctors to understand the right set of parameters for interventions based on aortic size index, which encompasses both aneurysm size and the patient’s BMI.
Source:
http://www.ncbi.nlm.nih.gov/
http://aneurysm-signs.com/