OP
Surgery is an absolute must in type A aortic dissection, as the mortality rate with conservative therapy is 50%. In addition, it is an absolute emergency indication, as the mortality rate increases by 1% with every passing hour. The operation is performed under general anaesthesia.
An aortic stent can be inserted to bridge the area of dissection. This is pushed over a large blood vessel on the thigh to the front part of the aorta, where it lines the aorta. A different procedure is used to implant a plastic prosthesis in the place of the ascending aorta.
For this, the thorax has to be opened. The patient is connected to the heart–lung machine, which takes over the pumping function of the heart for a certain period of time. The heart is then immobilised with medication, as a prosthesis implantation cannot be performed on the beating heart.
Since aortic dissection type A is the more dangerous of the two dissection types, implantation of the plastic prosthesis on the open thorax is favoured. The aortic stent is only used if the surgical risk is too high due to, for example, previous lung diseases. Since aortic dissection type A is a dangerous disease, consistent aftercare is absolutely necessary.
After the operation, this initially consists of monitoring in the intensive care unit and later on a normal ward. This is followed by a rehabilitation programme which treats the physical and psychological aspects of the disease. In the long term, a good blood pressure setting is essential.
CT examinations are also carried out regularly. This allows a renewed dilatation in the area of the ascending aorta to be detected and treated early on. In the prognosis of survival one speaks of various critical points in time.
The so-called “first hit” is the immediate time of dissection before the person reaches the hospital. Often, type A dissection is accompanied by a large loss of blood, where a volumetric dose and emergency surgery must be performed within minutes. The “second hit” is the surgery itself.
About 80% of the operated persons survive. The “Third Hit” summarizes possible complications that may occur within the next month and depends largely on how much other organ systems have been damaged by the blood loss. The brain and kidneys are particularly sensitive.
Causes
The causes of type A aortic dissection are manifold. Particular risk factors are high blood pressure (arterial hypertension) and arteriosclerosis (calcification of the blood vessels). Due to the increased blood pressure, more forces build up on the vessel wall.
In addition, the structure of the wall can be weakened by the calcifications. In combination the two diseases can lead to a splitting of the aortic wall. Connective tissue diseases can also be a reason for aortic dissection.
As a result of the disease, the vessel wall is structured differently than in healthy people. As a result, it is often unable to counteract the forces that exist in the aorta for a lifetime. The best-known connective tissue diseases that are particularly frequently associated with aortic dissections are Marfan and Ehlers-Danlos syndrome.
Other vasodilating diseases originate from the autoimmune group of forms. These are diseases in which the body attacks itself. This can, for example, lead to inflammation and thus weakening of the vessel walls.
Specific causes of aortic dissection type A are causes such as trauma in the region of the thorax. This often occurs in car accidents where large forces are exerted on the thorax by the seat belt or steering wheel. Surgery on the aorta, such as bypass surgery, can also weaken the vessel wall and thus cause a dissection in the region of the ascending aorta.
