Aortic Arch

    
Aortic aneurysms may result from a variety of predisposing conditions.

Degenerative dilation of the aortic wall is the most common cause of aneurysm formation. While the causes are not well understood, in some patients the elastic aortic tissue weakens prematurely, leading to progressive aneurysmal change. This process is sometimes referred to as cystic medial degeneration.

Atherosclerotic disease may produce calcification in the wall of the aorta, and other blood vessels, which damages cells in the media, leading to subsequent dilatation. Poorly controlled hypertension, as it subjects the aortic walls to higher pressure, may also contribute to aneurysm growth. Atherosclerosis has been found to be related to such factors as elevated cholesterol levels, cigarette smoking, diabetes, poor physical conditioning, and genetic predispositions.

Genetic diseases
, such as Marfan’s Syndrome or Ehlers-Danlos Syndrome, may lead to progressive dilatation of all segments of the aorta due to abnormalities in collagen, one of the proteins that are vital to the integrity of the aortic wall.

Aortic dissections may result in chronic dilatation of the aorta over time. An aortic dissection is caused by a tear in the inner lining of the aorta which allows blood to track within the wall of the aorta. Dissections of the ascending aorta must be repaired immediately, but dissections of the descending aorta may heal with careful blood pressure control. However, since the wall of the aorta is weakened, it may progressively dilate over time.

Inflammatory conditions, such as Takayasu’s arteritis, may produce aneurysmal changes of the aorta as one of their manifestations.

Trauma, for example from motor vehicle accidents, may damage the wall of the aorta, leading to late aneurysm formation.

Bicuspid aortic valves may produce chronic dilatation of the ascending aorta, and may require replacement of both the aortic valve as well as the ascending aorta.

The decision to operate on aortic arch aneurysms is based on a number of criteria, namely symptoms, size, growth rate, and family history.

Symptoms

 In the setting of an aortic arch aneurysm, chest pain is a concerning symptom and may prompt urgent repair. If you have an aneurysm and are experiencing chest pain, you should contact your physician or the nearest emergency room immediately.

Size

 While there is no absolute size cutoff, most surgeons will begin to recommend repair of aortic arch aneurysms when they reach ~5cm in size. For patients with Marfan’s Disease, surgery may be recommended for smaller sizes. Even patients with smaller aneurysms should be followed with CT scans at regular intervals to evaluate growth of the aneurysm, as directed by their physician.

Growth Rate

 The rate of change in size of an aortic arch aneurysm may also influence the timing of surgery. Generally, the faster the aneurysm grows, the sooner it should be repaired.

Family History

Operation may be recommended sooner based on a patient’s individual family history. Those with history of genetic diseases, such as Marfan’s, Ehler’s-Danlos or other family history of aortic diseases may be candidates for surgical treatment earlier in their course.

Trigraft Technique


For replacement of the aortic arch, we use a technique involving a Dacron graft with separate limbs for each of the arch vessels. This allows with resection of the entire aortic arch and separation of each of the arch vessels. Each of these vessels is then sewn to each limb of the trifurcated graft. The aortic arch is replaced with a separate graft, and, when complete, the trifurcated graft is connected to the arch graft. One of our faculty, Dr. David Spielvogel, was instrumental in the development of this technique and has published extensively on its use.

 

Prevention of stroke remains one of the central challenges in aortic surgery, and our practice takes numerous precautions to minimize the risk of neurologic complications. Strokes in complex aortic surgery may be the result of emboli (usually tiny particles of calcium or debris) which travel to the brain and cause damage. Some of our strategies for neurologic protection are below.

Axillary Cannulation

As many patients with aortic disease have widespread atherosclerotic disease throughout the aorta, we routinely avoid using the ascending aorta itself for access for cardiopulmonary bypass. Our standard approach for aortic surgery uses the left axillary artery for connection to the cardiopulmonary bypass circuit, which has been associated with decreased embolic associated neurologic complications.

Deep Hypothermic Circulatory Arrest (DHCA)

For many complex aortic operations, it is necessary to completely stop all blood flow within the body for a short period of time to gain safe access to certain areas of the aorta. This is accomplished by cooling the patient to very low temperatures using the cardiopulmonary bypass circuit as well as cooling blankets and packing ice around the patient’s head. With appropriate cooling and other adjunctive measures, blood flow can be stopped safely with full neurologic recovery.

Selective Cerebral Perfusion

For aortic arch replacements, as the procedure is performed, flow can be reinstituted via the trifurcation graft once completed. This allows for earlier re-establishment of blood flow to the brain, a shorter period of circulatory arrest and less chance of neurologic deficit.