Aortic aneurysm - Causes, symptoms and treatment. MF.
Aortic aneurysm is an extension of the aortic site due to a pathological change in the connective tissue structures of its walls due to an atherosclerotic process, inflammatory lesion, congenital inferiority or mechanical damage.
Figure 1. Schematic representation of the normal thoracic aorta and its aneurysm.
Depending on the location of the aneurysm, an aneurysm of the thoracic aorta, thoraco-abdominal( thoraco-abdominal) aorta and abdominal aorta is isolated. In turn, an aneurysm of the thoracic aorta can be divided into an aneurysm of the sinuses of the aorta, an aneurysm of the ascending aorta, an aneurysm of the aortic arch and aneurysm of the descending aorta.
In addition, the exfoliating aortic aneurysm, a pathological cavity or channel, formed in the thickness of the aortic wall due to exfoliation by blood from the aortic lumen through the intima defect( inner vessel shell), which arises from pathological process or damage, is particularly prominent. The dissection of the aortic wall takes place within its middle shell.
Causes of aortic aneurysm
The most common aortic aneurysm develops as a result of an atherosclerotic process or has a syphilitic origin. Recently, the first place among the causes of the development of an aneurysm of the aorta is its atherosclerosis, which is due to success in the treatment of syphilis and an increase in the average life expectancy. In addition, syphilis is more likely to cause aneurysm of the thoracic aorta, while atherosclerosis often leads to the formation of an aneurysm of the abdominal part.
Other causes of aortic aneurysm development are medionecrosis and nonspecific aortoarteritis. Traumatic aneurysms are also possible( for example, after closed abdominal trauma) and false aneurysms of anastomoses after operations on the aorta. Aneurysms of mycotic( fungal) origin are also described in scientific medical literature.
The most common cause of the development of exfoliating aortic aneurysm is long-term arterial hypertension in the background of atherosclerosis. In this case, on the inner membrane( intima) of the aortic wall, as a rule, pre-existent various small defects already exist. Less often, as a cause of exfoliating aortic aneurysm, hypertension may occur against coarctation of the aorta( congenital malformation manifested by segmental narrowing of the aortic lumen);arterial hypertension caused by other factors;Marfan syndrome( hereditary pathology of connective tissue), which is accompanied by severe weakness of the aortic wall. It is possible to form an acute exfoliating aneurysm of the ascending aorta due to its rupture, which is caused by a closed trauma( for example, an automobile).Sometimes exfoliating aortic aneurysm can occur as a result of iatrogenesis: as a complication of cannulation of the arteries and aorta for the purpose of perfusion with artificial blood circulation.
Symptoms of aortic aneurysm
Clinical manifestations of aortic aneurysms are determined by the compression( compression) of their surrounding organs, respectively, depending on their location and the rate of increase in their size. In the final stage of the disease, aortic aneurysms often erupt into a nearby hollow organ, pleural, abdominal cavity, or heart sac. Sometimes a breakthrough occurs in the pulmonary trunk with the formation of an aorto-pulmonary shunt.
The aortic sinus aneurysm may be accompanied by aortic valve failure or a narrowing of the luminal coronary arteries. Reaching a large size, such an aneurysm can squeeze the pulmonary trunk, right ventricle and right atrium, which leads to the formation of subacute right ventricular heart failure characterized by an increase in the liver, swelling of the cervical veins and the appearance of edema. Rapid compression of the pulmonary trunk with an aneurysm can lead to a sudden death of the patient.
The aneurysm of the ascending aorta manifests itself, as a rule, with blunt chest pains, which in some patients are accompanied by reflex attacks of dyspnea. If the aneurysm reaches a large size, it can cause atrophy of the adjacent sections of the sternum and ribs, with a pathological vascular pulsation in the second-third intercostal space to the right of the sternum. The compression of the aneurysm of the inferior vena cava or the breakthrough into it of the aneurysm leads to the development of the syndrome of the inferior vena cava, which in turn causes the joining of the edema of the neck, face, hands, swelling of the cervical veins.
An aneurysm of the aortic arch is most often manifested by dyspnoea( usually it is more difficult to inhale) due to compression of the trachea and bronchi. The compression of the left main bronchus by an aneurysm can lead to atelectasis( collapse) of the left lung. Sometimes hemoptysis appears, which may precede breakthrough aneurysm. The compression of the left lower-nerve nerve with an aneurysm is manifested by dry cough, attacks of suffocation, changes in the timbre of the voice( its hoarseness).Possible development of the syndrome of the superior vena cava. When the aneurysm of the brachiocephalic trunk, the left subclavian and the left common carotid arteries are compressed, symptoms of a gradually worsening violation of the blood supply of the upper limbs and head appear. Aortic aneurysm can be broken into the esophagus or trachea, which, as a rule, develops gradually, which is manifested initially by the appearance of scanty bloody vomiting or hemoptysis, but then massive bleeding develops.
Aneurysm of the descending aorta leads to compression of the nerve roots, vertebral bodies, esophagus and left lung. The compression of the nerve roots leads to the emergence of intense pain, resistant to the introduction of the most powerful analgesics. The pressure on the vertebral bodies and the posterior parts of the ribs leads to their deformation, up to the point that the aneurysmal sac can protrude between the inner edge of the left scapula and the vertebral column. In these patients, lower paraplegia may develop( complete loss of the possibility of voluntary movements of both lower limbs).The compression of the aneurysm of the left lung leads to its atelectasis and creates favorable conditions for the onset of pneumonia. The compression of the esophagus in some cases can lead to difficulty in passing through it food( dysphagia).When the wall of the esophagus is destroyed due to prolonged pressure on her aneurysm, small bleeding occurs from the esophagus, after which, as a rule, an aneurysm breaks into its lumen with the development of massive bleeding. With the breakthrough into the pleural cavity of the descending aortic aneurysm, rapidly growing anemia( anemia) and large hemothorax( accumulation of blood in the pleural cavity) develop.
The aneurysm of the thoracoabdominal aortic is rare, usually due to syphilis. The aneurysm compresses the esophagus and the upper part of the stomach, which leads to the appearance of pressing pains in the epigastric region, which can be associated with food intake, sometimes - belching, vomiting, disruption of food passage through the esophagus. Aneurysm of the thoracoabdominal aorta can cause narrowing or complete overlap of the lumen of the superior mesenteric artery and celiac trunk, blood supplying the abdominal cavity organs, which is manifested by attacks of painful abdominal pain( the so-called abdominal toad).Because of the above-described causes of an aneurysm of this localization leads to weight loss of the patient.
Aneurysm of the abdominal aorta over time is manifested by pain caused by aneurysm pressure on the nerve plexus and nerve roots, located immediately next to it. Pain can be in the lumbar or epigastric region. A large aneurysm, located below the site of the renal arteries, can squeeze the ureters, causing the development of hydronephrosis and anuria. If there is compression of the renal arteries, symptomatic arterial hypertension appears. When the aneurysm of the duodenum is squeezed, the food masses pass through it, which is manifested by vomiting and weight loss. Most often an aneurysm of the abdominal aorta is manifested by the presence of a pulsating tumor-like formation in the abdominal cavity at the navel level or slightly lower and slightly to the left of it. The thrombosed aneurysm does not pulsate, which is why it can be mistaken for a tumor. Sometimes there is a rise in body temperature. The breakthrough of an aneurysm into the abdominal cavity occurs quickly and, as a rule, painlessly, and into the retroperitoneal tissue - with severe pain in the abdomen and lower back, with the development of shock phenomena. After a while, the patient may die because of increasing blood loss.
The dissecting aortic aneurysm of is manifested with sudden acute pains in the chest, not removed by painkillers, and collapse. Sometimes there is a complete loss of the possibility of voluntary movements of both lower limbs, which may be temporary or permanent. Because of the peculiarities of localization and the nature of the pain that occurs, the clinical manifestations of the exfoliating aortic aneurysm can be mistaken for acute myocardial infarction. Complications of the aortic aneurysm
1. Aortic valve defects and heart failure .With an aneurysm of the ascending aorta of syphilitic origin, cardiac decompensation may develop due to the aortic valve defect or the overlap of the coronary artery mouth.
2. Aneurysm rupture with bleeding .Bleeding can occur in the respiratory system( bronchi, trachea), the pleural cavity, the heart bag, the esophagus, the large blood vessels located in the chest cavity, and sometimes even out through the skin when the sternum is destroyed. In case of bleeding, a cardiac tamponade arises in the pericardial cavity. Bleeding leads to rapidly increasing blood loss.
3. Acute and subacute thrombosis of the aortic aneurysm. Most often it develops in the abdominal aorta and leads to the closure of its branches located here.
These complications quickly led to the death of the patient, if appropriate measures are not taken in time.
Instrumental examination
X-ray examination. With aneurysms of the thoracic aorta, radiography is carried out in three projections with the necessary contrast of the lumen of the esophagus. The broadening of the shadow of the vascular bundle is characteristic. Aneurysms of the descending aorta bulge into the left pulmonary field. In most patients there is a displacement of the contrasted esophagus. Sometimes calcification( calcification) of the aneurysmal sac is determined. With aneurysms of the abdominal aorta, an overview radiograph of the abdominal cavity in two projections allows revealing the calcification of the aortic wall and the usurpation of the vertebral bodies of the lumbar region.
Figure 2. An overview radiograph of the thoracic organs of the patient with an aneurysm of the arch and a descending thoracic aorta.
Ultrasound examination( ultrasound) of the aorta and heart. The ultrasound can detect the presence and size of the ascending, descending aorta, the aortic arch, the abdominal aorta, the state of the vessels leaving the aorta, and the presence of aortic valve defect, the character of the aortic wall changes.
Computed tomography( CT) .With aortic lumen greater than 4 cm, its enlargement is considered an aneurysmal enlargement. When computed tomography is performed, it is possible to determine the involvement of large arteries in the process and to reveal signs of dissection( dissection) of the walls( with aortic dissecting aneurysm).
Angiographic examination( aortography).It is used, as a rule, before an operative intervention in planning its nature and volume.
Figure 3. Angiograms of aneurysms of the ascending and descending parts and the arch of the thoracic aorta.
Treatment of a patient with aortic aneurysm
An aneurysm of the thoracic aorta, having a diameter of more than 5 cm, is subject to prompt treatment because of the high risk of rupture and development of thromboembolic complications. Surgical intervention is performed in conditions of artificial circulation and hypothermia( low temperature) and reduces to resection( removal) of an aneurysm with a one-stage replacement of the removed site with a prosthesis.
In the asymptomatic course of the aneurysm of the abdominal aorta, the indication to the planned surgical intervention is its diameter more than 4 cm. In cases of the increase of the pain syndrome and the threat of rupture, an emergency surgical intervention is indicated. The operation is reduced to resection of an aneurysm with a direct prosthesis of the abdominal aorta or performing a bifurcational aortibular prosthesis.
Prognosis for aortic aneurysm
In the absence of timely treatment and the occurrence of severe complications of the aortic aneurysm, the forecast is unfavorable. Lethal outcome can occur as a result of decompensation of cardiac activity caused by the development of aortic valve defects in an aneurysm of the ascending aorta, cardiac tamponade due to the breakthrough of an aneurysm into the pericardial cavity, massive blood loss as a result of aneurysm breakthrough into the hollow organs and the pleural or abdominal cavity.
However, the successes achieved at the present time in the surgical treatment of aortic aneurysms make it possible to save life for the majority of patients in the case of timely and adequate surgical intervention. At the planned operation the lethality is 0-5%, and in case of rupture of an aneurysm, even with an emergency surgery is 50-80%.Five-year survival among operated patients is 80%, and among the unoperated - 5-10%.
Doctor surgeon Kletkin ME