Dilations of the aorta, or aortic aneurysms, are treated surgically with vascular stents and vascular prostheses. Depending on the position and size of the aneurysm, open repair is performed or the stent can be inserted into the aorta over an artery in an endovascular procedure.
The aorta or main artery is the largest artery in the human body. It originates from the left ventricle of the heart and extends downwards as the thoracic aorta and the abdominal aorta into the pelvis. From there it branches out into the pelvic arteries. Arteriosclerosis can develop in the aorta over time, as in all arteries. In contrast to the smaller arteries, this does not necessarily lead to constrictions in the large main arteries but rather to a weakness in the artery wall with formation of dilations (aneurysms). Arteriosclerosis is the most common cause of aortic aneurysms. Marfan syndrome is a rarer, genetic disorder that affects the connective tissue.
There is a high risk that an aortic aneurysm will rupture from a particular size and lead to fatal haemorrhaging. Therefore, aortic aneurysms must be treated surgically from a size of around 5 cm and the affected section replaced with a vascular prosthesis.
Aortic aneurysm operation
Up to approx. 15 years ago, it was only possible to use a vascular prosthesis in a highly risky operation on an open aorta. Nowadays, an aortic replacement can take place with substantially less risk without opening the aorta. This is done with an endovascular procedure using self-expanding stent grafts. The position and size of the aneurysm determine whether such a procedure is even possible.
What preparations are carried out before the procedure?
Prior to the procedure, the exact location and extent of the aneurysm is determined by CT, MRI, ultrasound and aortography examinations. A vascular prosthesis can only be securely affixed when there is a sufficiently long piece of undilated aortic wall without larger aortic branches above and below the aneurysm. As the cardiac or cerebral arteries are also often affected by arteriosclerosis of the aorta, they too are closely examined before an operation. Any narrowing in the coronary or the cerebral arteries may still have to be addressed before the aorta operation. Otherwise, the patient runs the risk of suffering a heart attack or a cerebral infarction during the operation.
All the usual pre-operative assessments, such as a blood test, blood pressure measurement and an ECG are required. The patient must stop taking blood-thinning medication, and is usually admitted to hospital on the day before the surgery. They should be sober for the operation.
How is the operation performed?
An operation on an open artery is necessary on the one hand when the aneurysm is situated in the ascending part of the aorta or in the aortic arch, and on the other when the dilation is too large for a self-expanding stent. An operation on the ascending branch of the aorta or on the aortic arch is always done over a frontal access point with separation of the breastbone (sterniotomy). The patient must be attached to a life support machine for the operation, which generally takes three to four hours. More often than not, it can take considerably longer and a hospital stay of eight to fourteen days cannot be avoided. If the aneurysm is in the chest or abdominal aorta, the incision is made over the opening of the chest or the abdomen.
Endovascular procedures with stent grafts
Endovascular procedures are much smaller, less strenuous on the patient and can generally be performed under local anaesthetic and light sedation. The life-support machine does not need to be used in this case. Access is granted by opening the arteries in the groin. Vascular prostheses are inserted through this opening, positioned and anchored on the dilated aortic section with the help of fluoroscopic imaging. During endovascular procedures, preparations are also made for an open-heart procedure so the medical team can immediately switch to this in the event of an emergency. The procedure takes one to two hours and the patient must remain in hospital for three to six days.
What is the success rate of this procedure?
The rate of recovery after successful aortic replacement is good. The main risks are complications which can occur during and immediately after the operation.
What are the possible complications and risks of this procedure?
An open-heart aortic replacement operation is an extremely risky procedure; however, the level of risk depends greatly on the general condition of the patient and comborbidities such as heart, pulmonary or renal disease. After the operation, the patient needs to be monitored for several days.
In comparison to the open-heart operation, the endovascular procedure is considerably less risky.
What happens after the operation?
After undergoing an open-heart operation, patients may carry no more than five kg for two months. The section of the aorta replaced with Dacron can no longer change. For this reason, the implants do not need to be specifically checked. On the other hand, the rest of the aorta should be sporadically examined to check that a new aneurysm has not formed.
Regular check-ups are required after endovascular procedures, primarily in the early days. Stent grafts can sometimes shift slightly and cause leakages to occur. Check-ups usually take place after six months, one year and then every two years post-operative.