How deep is the abdominal aorta
- Supra-coronary replacement of the ascending aorta (ascending aorta)
- Aortic arch replacement
- Composite replacement
- David operation
The aorta is the largest arterial blood vessel in the human body.
Separated by the valve-like aortic valve, it arises from the left ventricle. Its course begins with an upward movement towards the neck, then makes an arc, from which several vessels branch off to the arms and head, and then runs downwards into the pelvis. On the way through the chest and abdomen, the intercostal arteries and other large arterial vessels supply the intestines.
The aorta consists of three layers, an inner vascular cell layer, a middle muscle layer and an outer layer of connective tissue. The aorta has an average diameter of 2.5-3.5 cm. During the normal aging process, it increases by an average of 35% between the ages of 20 and 70. An abnormal enlargement or localized bulge beyond this 35% that affects all three wall layers is called an aortic aneurysm. This can occur in all sections of the aorta (ascending part, aortic arch, and descending part).
An aortic dissection is a disease in which the inner vascular layer tears and the muscle layer is lifted from the inner vascular layer of the aorta by the blood flow into the defect. This creates a second cavity (lumen) inside the aorta in which the blood flows.
Causes and origins
The causes of aortic aneurysms and aortic dissections are diverse. In 90-95% of cases arteriosclerosis and high blood pressure are the cause. Plaques (calcium deposits) embedded in the vessel wall damage the wall structure. The elasticity of the vessel decreases significantly and hardening occurs. If the already damaged vascular wall is also exposed to chronically high blood pressure, plaque rupture (tearing off of the calcium deposit) can occur, as a result of which the remaining vascular wall can no longer withstand the pressure and expands (similar to a balloon, the wall of which expands and diluted when inflated or watered in). Isolated tearing of the inner vascular layer (intima) is also possible, resulting in an aortic dissection. In the worst case, the entire vessel wall can rupture (tear), causing large amounts of blood to flow into the chest or abdomen (depending on the location of the defect). In the case of large tears, this leads to cardiovascular shock. Less than 10% of all patients who experience an aortic rupture survive. Only 10-15% reach the clinic alive and only about half of them can be saved through an emergency operation. The risk of rupture in the aoric aneurysm is particularly high if the aorta diameter is> 5 cm.
Another, less common cause of aortic aneurysms and aortic dissections are connective tissue diseases (e.g. Marfan syndrome, Ehlers-Danlos syndrome, cystic median necrosis Erdheim-Gsell), which are associated with a defective structure of the vascular connective tissue and subsequent instability of the entire vascular wall. Also to be mentioned are inflammatory diseases, such as in the late stage of syphilis, Takayasu arteritis (both nodules in the vessel wall with tissue damage) or congenital malformations, which are possible causes of the development of an aortic aneurysm. Hormonal changes (e.g. during pregnancy), injuries to the chest or contact with harmful substances (e.g. use of cocaine) can also play a role in the development of aortic dissection.
The aortic aneurysm is a common incidental finding in x-ray exams. In addition, complaints such as hoarseness (due to irritation of the recurrent laryngeal nerve - larynx nerve), shortness of breath due to compression of the trachea, pain in the shoulder and back due to the displacement of neighboring structures, and coughing up blood can also occur.
Aortic dissection can occur suddenly (acutely). In these cases the patients describe a so-called annihilation pain that is almost unbearable and is accompanied by fear of death. Symptoms of a myocardial infarction (chest pain, shortness of breath, etc. -> see CHD) due to accompanying reduced blood flow to the heart muscle, as well as those of a stroke with paralysis, double vision and loss of sensitivity due to reduced blood flow to the brain and spinal cord can occur. Furthermore, severe abdominal pain due to the interruption of the blood flow to the intestine and a lack of urine due to the interruption of the blood flow to the kidney are possible.
Chronic aortic dissections, on the other hand, often cause back pain with wandering localization and character. The symptoms of "shop window disease" with pain in the legs when moving can also occur in the context of an aortic dissection. Furthermore, the above-mentioned complaints of the aortic aneurysm also apply to chronic aortic dissection.
Changes to the aorta can be visualized on transesophageal echocardiography (ultrasound using an ultrasound probe that is placed over the esophagus near the aorta). Computed tomography of the chest is best suited for the precise localization and determination of the extent of a dissection or aneurysm.
The aorta is always accessed via a median sternotomy. To do this, the entire length of the breastbone (sternum) is opened up. The two halves of the sternum are held apart with a ratchet so that the surgeon can work on the chest organs.
The use of the heart-lung machine is a prerequisite for almost all operations on the ascending aorta and the aortic arch. Since the blood is normally transported from the heart via the aorta into the entire body circulation, particularly into the brain, the blood must now be diverted via the heart-lung machine. The blood that is otherwise drawn into the heart is sucked out through a cannula from the right atrium or through two cannulas that are inserted into the upper and lower vena cava. Once in the heart-lung machine, oxygen is added. In most cases, the oxygen-enriched blood is returned to the head via a cannula in the right axillary artery (in both axillary arteries for aortic arch replacement). If necessary, blood can be supplied through a cannula in the inguinal artery or in a part of the aorta remote from the aneurysm. The rest of the body remains in cardiac arrest. In order to cause the body tissues to consume a minimum of oxygen, the body is cooled down.
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