Wednesday, August 11, 2010

Cleveland Clinic Formula For Aneurysm Surgery

Photo: One of the lovely roses in our garden.

This summer has been quiet on the medical front. Other than the fact that I get easily winded and I do not have any reserves to call upon in a situation that calls for extra physical effort or exertion, I feel fine. As my aortic stenosis progresses and the valve opening gets smaller and smaller, my heart just can't pump enough blood through my aortic valve to support increased levels of exertion. I am disappointed that I can't do all that I want to do or used to do physically. For example, I'm afraid to go out actually swimming in the ocean in water any deeper than about waist high, because if I were to get caught in a current, I simply no longer have the strength to fight my way back in. I used to be able to handle this sort of situation, but I can't anymore.

When you have an aortic aneurysm, it's like having a defective tire on your car. It could blow at any time. However, to get it fixed surgically, it has to be a certain size. I've been trying to find this formula for a while now.

An aorta that is enlarged and forming an aneurysm can be repaired, but at Cleveland Clinic we more often replace the damaged section with a section of plastic tubing that is sewn into position. The timing for repair of an aortic aneurysm is critical. When the valve is faulty and the aorta has enlarged to greater than 4.5 cm, we repair the aorta at the same time we repair or replace the valve. If the aorta has enlarged but the valve is still good, the optimal time to repair the aorta varies. At Cleveland Clinic, we have developed a special mathematical formula we use to determine this, based on the patient’s height and weight and the size of the aorta - surgery is usually recommended when the aortic cross sectional area in square centimeters, divided by the patient's height in meters is more than 10.


If I understand this correctly and my calculations are correct, here are two examples:

I am 6'5" tall, which is 1.96 meters. Currently my ascending aorta is at 4.5 cm diameter, which calculates to a cross sectional area of 15.9 cm2. 15.9 divided by 1.96 = 8.1 which is less than 10, not time yet for surgery.

If and when my ascending aorta reaches 5.0 cm in diameter it will then have a cross sectional area of 19.6 cm2. 19.6 divided by 1.96 = 10, which is the recommended trip point for surgery on my aorta.

I'm a taller than average person. Based on a person that is, say 5'10 inches tall, the calculations are different. A person that height will have a calculated formula factor of 8.9 when her aneurysm is at 4.5, still not yet time for surgery. However, when her aneurysm reaches 4.7 cm, her formula factor rises to 9.8, and when the aneurysm is 4.8 cm across, her formula factor is then 10.2, and surgery would be recommended according to the Cleveland Clinic formula.