Aortic Arch Replacement
Aortic arch replacement or repair can be done for aneurysmal disease of the aortic arch in asymptomatic patients when the size of the aortic arch exceeds 5.5 cm.
Some facts about Aortic Arch Replacement:
- The entire aortic arch needs to be repaired in patients with acute aortic dissection when the arch is aneurysmal or else there is extensive aortic arch destruction and leakage
- Repair is also needed when there is an infected aneurysm or when there is significant plaque present in the arch that has resulted in strokes.
- Repair is also required if the a growth rate of more than 0.5 cm/year in the absence of symptoms
- Hoarseness, difficulty in breathing, difficulty in swallowing, and chest or back pain are symptoms associated with aortic arch aneurysms which are indications for operative intervention.
- Reimage using computed tomographic imaging (CT scan) or cardiac magnetic resonance imaging (Cardiac MRI) is advisable for patients with isolated aortic arch aneurysms less than 4.0 cm in diameter, at 12 month intervals to detect enlargement of the aneurysm.
- Reimage using computed tomographic imaging or cardiac magnetic resonance imaging (Cardiac MRI) is advisable for patients with isolated aortic arch aneurysms 4.0 cm or greater in diameter, at six month intervals to detect enlargement of the aneurysm.
Procedure for Aortic Arch Replacement:
- Excision of the ascending aorta as well as underside of the aortic arch, and placement of a thoracic aortic stent graft into the descending aorta at the time of arch repair is involved in this procedure..
- Temporary interruption of the blood flow to the blood vessels that supply the brain is required Aortic arch procedures.
- The core temperature of the body needs to be progressively reduced to 18 to 20 degrees Celsius for safe interruption of the blood flow to the brain.
- The metabolism is reduced significantly in that cold body temperature, which allows cessation of the blood flow to the body for 30 to 40 minutes without side effects.
- The aortic arch is replaced with a synthetic tube under these conditions which is attached to normal segments of the ascending and descending thoracic aorta.
- A separate synthetic tube with three branches (trifurcation graft) is used to reconnect the arch blood vessels (brachiocephalic, left carotid, and left subclavian arteries) that supply the brain amongst other organs to the synthetic graft
- Insertion of catheters in the individual arch blood vessels is allowed by this technique for perfusion of the brain with blood (selective cerebral perfusion), while all these connections are being created.
- Only the undersurface of the aortic arch can also be removed in certain circumstances, leaving intact a narrow strip of the upper part of the aortic arch containing the arch vessels (hemiarch technique).
- Invariably a shorter period of hypothermia is required for this simplified method.
- The complexity of the operation can be significantly reduced by using this techinique.
- The electroencephalogram (EEG) and the somatosensory evoked potentials (SSEP) techinique can be utilized to monitor the brain function during these operations, irrespective of the technique of aortic arch replacement.
- The electrical activity of the brain can be accessed during different phases of the operation and help the surgeon determine the safety of the protection techniques that are used.
