Surgical Treatment of Aortic Aneurysms and Dissections
Aortic aneurysm is the ballooning out of the wall of the aorta, the biggest blood vessel of the body. This blood vessel comes directly from the heart, from where it carries blood to other parts of the body. The balloon-like configuration is a result of the weakening of all the layers of its wall. Treatment is either medical (taking of medications to possibly slow down increase in size) or surgical (involves repair of the walls of the blood vessel).
Aneurysm may occur at any part:
- Along where the aorta has just come out from the heart (called the ascending aorta),
- Along the part where it forms an arch (aortic arch)
- Along the part that goes downward (descending aorta). The descending aorta has two parts, that which is still within the chest is called descending thoracic aorta and that which has entered the abdomen is called abdominal aorta
Possible causes are:
- Atherosclerosis: Plaques get deposited along the inner wall of the blood vessels (in this case the aorta). Initially they are waxy, but later harden and cause deterioration of the tissues of the aortic wall that leads to weakening. This is the most common cause
- Syphilis: This is a sexually transmitted infection that causes multiple organ destruction but no longer seen nowadays
- Congenital (existing since birth): The abnormality is related to faulty development of the foetus (as in Marfan's syndrome)
- Genetic: More than one member of the family may get the same condition
- Blunt trauma to the chest or abdomen
Signs and symptoms
In its early stages an aneurysm doesn't have symptoms. Later, when it has grown bigger and has started to put pressure on neighbouring organs symptoms start to manifest.
- Chest pain (for thoracic aortic aneurysm) which is often described as deep and throbbing
- Cough or shortness of breath
- Pain upon swallowing, or difficulty of swallowing
- Back pain
- Abdominal discomfort or pain (for abdominal aortic aneurysm)
Test are taken to help determine size, location, and possibility of rupture (which is fatal), and therefore the decision whether the patient is a candidate for immediate surgery or surgery in the near future.
- CT scan
- Magnetic resonance angiogram
- Transthoracic echocardiogram
- Transoesophageal echocardiogram
Surgery is recommended for patients with:
- Presence of symptoms (any combination mentioned above)
- Aneurysms 5.5 cm or larger in diameter for males; smaller diameter for females
- Aneurysms that are increasing in diameter fast (diameter has increased more than 0.5cm in 6 months)
- An aneurysm that is evaluated as about to rupture
Surgical procedures for aortic aneurysm
- Open surgery under general anaesthesia using the heart-lung machine where the aneurysm is removed and the wall repaired with a man-made graft. This is the traditional method and has a proven high success rate
- Endovascular aortic repair. This is a newer technique where the patient is just sedated. Under local anaesthesia a tube (catheter) is inserted through a cut in the artery of the groin which is navigated upwards to where the defect is located. Then, a stent graft (a tube-like device made of fabric and mesh wire) is inserted through the catheter towards the defect, and thus mechanically reinforcing it. It has been highly successful but its long term effect is still not known yet. This procedure is usually performed by vascular surgeons sometimes working with cardiac surgeons depending on the location of the aneurysm
Aortic dissection is the tearing of the innermost layer of the wall of the aorta that results in the leakage of blood in between the inner layer and the middle layers of the aorta. As in aneurysm this could occur along any part of the aorta. Again, its most common causes are high blood pressure and atherosclerosis. Other possible causes are weakening of the aortic wall from inherited connective tissue disease, inflammation of the aortic wall and blunt trauma. Treatment may be medical and/or surgical.
Signs and symptoms
- A very severe ripping kind of pain in the chest or the abdomen (depending on its location but often radiating), onset is usually sudden
- Dizziness or fainting
- Excessive sweating
- Mental haziness or confusion
Test to confirm the diagnosis
- CT scan
- Transoesophageal echocardiogram
These tests help determine the location and the extent of the condition and therefore help in the decision to make the surgical procedure and how the surgery is best approached.
Types of aortic dissection and their treatment
- Type A: This involves the ascending aorta. This condition is immediately life threatening with a very high risk of death if not treated emergently (within 24 hr). Other complications can occur including a high risk of brain injury, stroke and injury to other organs due to impaired blood flow. The treatment for this condition is emergent surgery
- Type B: This involves the descending aorta distal to the subclavian artery. The management of choice is medical and is geared towards lowering and maintaining blood pressure and preventing the spread or increase of the extent of the dissection. This type of dissection is not immediately life threatening
Surgical treatment of type A aortic dissection
Under general anaesthesia the chest is opened, the heart and circulation are supported with the heart lung machine and the extent of damage to the ascending aorta is assessed. The damaged area is removed and replaced with a graft. If there is damage to the aortic valve this is repaired or replaced as well.
If you have undergone surgery for either aortic aneurysm or aortic dissection, you may have to stay in the hospital for 5-14 days. During this time your cardiac and overall circulatory functions will be closely monitored. Medications in the form of antibiotics, pain relievers and antihypertensive drugs (to lower blood pressure) are given. The surgery is high risk but essential if the patient is to survive.
Upon discharge your nurse or Dr Orr will give you detailed instructions regarding wound care, possible complications, medications to maintain and schedules for follow ups. Make sure to list down all necessary contact numbers. Don’t hesitate to make Dr Orr if something unexpected occurs.