Repairing a thoracic aneurysm

Q. I have a thoracic aortic aneurysm that was discovered nearly five years ago. I've been getting yearly scans to monitor the size, and so far, it seems to be growing very slowly. But if it reaches a certain size, my cardiologist says I might need surgery. Are there any less invasive options to fix this problem?

A. Yes, some aortic aneurysms can be repaired with a nonsurgical procedure known as endovascular repair. However, the most appropriate treatment for an aortic aneurysm depends on not only the size but also the location of the aneurysm, as well as your age, overall health, and whether you've had any previous heart surgeries.

An aortic aneurysm is a weakened area in the wall of the aorta, the main pipeline for blood from the heart to the body. The section that curves out of the heart, the thoracic aorta, ends at the diaphragm, which separates the chest (a region known medically as the thorax) from the abdomen. Thoracic aneurysms can occur in the section closest to the heart (ascending aorta) or the straight section after the curved arch (descending aorta). Most occur in people with risk factors such as high blood pressure and high cholesterol. But some ascending aortic aneurysms occur in younger people with connective tissue disorders or a bicuspid aortic valve, in which the valve has two flaps instead of three.

Thoracic aortic aneurysms that stay small and stable are relatively harmless. But those that grow too large may bulge outward and rupture, which can lead to catastrophic bleeding. The size threshold for recommending a repair varies depending on the person.

Aneurysms in the descending aorta can sometimes be repaired with an endovascular stent graft (a tube made from a special fabric). For this procedure, the doctor inserts the folded graft through a tiny cut in a blood vessel at the top of the thigh, threads it up the aorta to the bulging section, and unfolds it. According to my colleague Dr. Eric Isselbacher, co-director of the Thoracic Aortic Center at Massachusetts General Hospital, this approach is much more technically challenging for aneurysms in the ascending aorta. As he explains, the graft needs to be snugly attached to the wall of the aorta where it arises from the heart, but this is where blood flow is most forceful. There are also other anatomical challenges, including the curve of the aorta and the coronary arteries that branch out from it. In the future, endovascular techniques may evolve to address those challenges. But for now, aneurysms in the ascending aorta need to be repaired with open heart surgery, in which the surgeon replaces the bulging part of the aorta with a graft and sews it into place.

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