Aortic aneurysm is a pathological local expansion of a section of the main artery due to the weakness of its walls. Depending on the location of the aortic aneurysm, it can manifest pain in the chest or abdomen, the presence of a pulsating tumor-like formation, symptoms of compression of neighboring organs: shortness of breath, cough, dysphonia, dysphagia, swelling and cyanosis of the face and neck. The basis for the diagnosis of aortic aneurysm is X-ray (chest and abdominal cavity radiography, aortography) and ultrasound methods. Surgical treatment of an aneurysm involves performing its resection with aortic prosthetics or closed endoluminal prosthetics of the aneurysm with a special endoprosthesis.
I71 Aneurysm and aortic dissection
An aortic aneurysm is characterized by irreversible expansion of the lumen of the arterial trunk in a limited area. The ratio of aortic aneurysms of different localization is approximately as follows: abdominal aortic aneurysms account for 37% of cases, ascending aorta – 23%, aortic arch – 19%, descending thoracic aorta – 19.5%. Thus, thoracic aortic aneurysms account for almost 2/3 of all pathology in cardiology. Thoracic aortic aneurysms are often combined with other aortic malformations – aortic insufficiency and aortic coarctation.
According to the etiology, all aortic aneurysms can be divided into congenital and acquired. The formation of congenital aneurysms is associated with hereditary diseases of the aortic wall:
- Marfan syndrome
- fibrous dysplasia
- syndrome Erdheim syndrome
- hereditary elastin deficiency, etc.
Acquired aortic aneurysms may have inflammatory and non-inflammatory etiology:
- Post-inflammatory occur due to specific and nonspecific aortitis in fungal aortic lesions, syphilis, postoperative infections.
- Non-inflammatory degenerative are caused by atherosclerosis, defects in suture material and aortic prostheses.
- Hemodynamic-poststenotic and traumatic are associated with mechanical damage to the aorta
- Idiopathic develop with medionecrosis of the aorta.
Risk factors for the formation of aortic aneurysms are considered to be old age, male gender, hypertension, smoking and alcohol abuse, hereditary burden.
In addition to the aortic wall defects, mechanical and hemodynamic factors take part in the formation of an aneurysm. Aneurysms are more likely to occur in functionally stressed areas experiencing increased stress due to high blood flow velocity, the steepness of the pulse wave and its shape. Chronic traumatization of the aorta, as well as increased activity of proteolytic enzymes, cause destruction of the elastic framework and nonspecific degenerative changes in the vessel wall.
The formed aortic aneurysm progressively increases in size, since the stress on its walls increases in proportion to the expansion of the diameter. The blood flow in the aneurysmal sac slows down and becomes turbulent. Only about 45% of the volume of blood in the aneurysm enters the distal arterial bed. This is due to the fact that, getting into the aneurysmal cavity, blood rushes along the walls, and the central flow is restrained by the mechanism of turbulence and the presence of thrombotic masses in the aneurysm. The presence of blood clots in the aneurysm cavity is a risk factor for thromboembolism of distal aortic branches.
In vascular surgery, several classifications of aortic aneurysms have been proposed, taking into account their localization by segments, shape, wall structure, and etiology. In accordance with the segmental classification
- aneurysm of the sinus of Valsalva is isolated
- ascending aortic aneurysm
- aortic arch aneurysm
- aneurysm of the descending aorta
- abdominal aortic aneurysm
- of combined localization – thoracoabdominal part of the aorta.
Assessment of the morphological structure of aortic aneurysms allows us to divide them into true and false (pseudo-aneurysms):
- True aneurysm is characterized by thinning and protruding outward of all layers of the aorta. By etiology, true aortic aneurysms are usually atherosclerotic or syphilitic.
- Pseudoaneurysms. The wall of a false aneurysm is represented by connective tissue formed as a result of the organization of a pulsating hematoma; the own walls of the aorta are not involved in the formation of a false aneurysm. By origin, they are more often traumatic and postoperative.
In shape, there are baggy and fusiform aortic aneurysms: the former are characterized by local protrusion of the wall, the latter by diffuse expansion of the entire diameter of the aorta. Normally, in adults, the diameter of the ascending aorta is about 3 cm, the descending thoracic aorta is 2.5 cm, the abdominal aorta is 2 cm. An aortic aneurysm is said to increase the diameter of the vessel in a limited area by 2 or more times.
Taking into account the clinical course, uncomplicated, complicated, delaminating aortic aneurysms are distinguished. Specific complications of aortic aneurysms include ruptures of the aneurysmal sac, accompanied by massive internal bleeding and the formation of hematomas; aneurysm thrombosis and arterial thromboembolism; phlegmons of surrounding tissues due to infection of the aneurysm.
A special type is a delaminating aortic aneurysm, when blood penetrates through the rupture of the inner shell between the layers of the artery wall and spreads under pressure along the vessel, gradually delaminating it.
Symptoms of aortic aneurysm
Clinical manifestations of aortic aneurysms are variable and are determined by the localization, size of the aneurysmal sac, its extent, and etiology of the disease. Aneurysms may be asymptomatic or accompanied by scant symptoms and be detected during preventive examinations. The leading manifestation is pain caused by a lesion of the aortic wall, its stretching or compression syndrome.
Abdominal aortic aneurysm
The clinic of abdominal aortic aneurysm is manifested by transient or permanent diffuse pains, abdominal discomfort, belching, heaviness in the epigastrium, a feeling of stomach overflow, nausea, vomiting, intestinal dysfunction, weight loss. Symptoms may be associated with compression of the cardiac part of the stomach, the duodenum, involvement of visceral arteries. Often patients independently determine the presence of increased pulsation in the abdomen. During palpation, a tense, dense, painful pulsating formation is determined.
Thoracic aortic aneurysm
For an aneurysm of the ascending aorta, pain in the heart or behind the sternum is typical, due to compression or stenosis of the coronary arteries. Patients with aortic insufficiency are concerned about shortness of breath, tachycardia, dizziness. Large aneurysms cause the development of the superior vena cava syndrome with headaches, swelling of the face and upper half of the trunk.
Aneurysm of the aortic arch leads to compression of the esophagus with dysphagia; in the case of compression of the recurrent nerve, hoarseness of voice (dysphonia), dry cough occurs; vagus nerve involvement is accompanied by bradycardia and salivation. With compression of the trachea and bronchi, shortness of breath and stridorous breathing develop; with compression of the lung root, congestion and frequent pneumonia occur.
When irritated by an aneurysm of the descending aorta of the periaortic sympathetic plexus, pain occurs in the left arm and shoulder blade. In the case of intercostal artery involvement, spinal cord ischemia, paraparesis and paraplegia may develop. Compression of the vertebrae is accompanied by their usuration, degeneration and displacement with the formation of kyphosis. Compression of vessels and nerves is clinically manifested by radicular and intercostal neuralgia.
Aortic aneurysms can be complicated by rupture with the development of massive bleeding, collapse, shock and acute heart failure. Aneurysm breakthrough can occur in the superior vena cava system, pericardial and pleural cavity, esophagus, abdominal cavity. At the same time, severe, sometimes fatal conditions develop – superior vena cava syndrome, hemopericardium, cardiac tamponade, hemothorax, pulmonary, gastrointestinal or intra-abdominal bleeding.
With the separation of thrombotic masses from the aneurysmal cavity, a picture of acute occlusion of the vessels of the extremities develops: cyanosis and soreness of the toes, livedo on the skin of the extremities, intermittent lameness. With thrombosis of the renal arteries, renovascular arterial hypertension and renal insufficiency occur; with damage to the cerebral arteries, stroke occurs.
Diagnostic search for aortic aneurysm includes the assessment of subjective and objective data, X-ray, ultrasound and tomographic studies. An auscultative sign of an aneurysm is the presence of systolic noise in the projection of aortic dilation. Abdominal aortic aneurysms are detected by palpation of the abdomen in the form of a tumor-like pulsating formation. Instrumental diagnostics:
- Radiography. The X-ray examination plan for patients with thoracic or abdominal aortic aneurysm includes chest X-ray, abdominal cavity, esophageal and stomach.At the final stage of the examination, aortography is performed, according to which the localization, size, length of the aortic aneurysm and its relation to neighboring anatomical structures are specified.
- Ultrasound. When recognizing aneurysms of the ascending aorta, echocardiography is used; in other cases, the ultrasound of the thoracic/ abdominal aorta is performed.
- Computed tomography. CT of the thoracic / abdominal aorta allows you to accurately and visually represent aneurysmal expansion, identify the presence of dissection and thrombotic masses, paraaortic hematoma, foci of calcification.
Based on the results of a comprehensive instrumental examination, a decision is made on the indications for surgical treatment. Thoracic aortic aneurysm should be differentiated from tumors of the lungs and mediastinum; abdominal aortic aneurysm – from volumetric formations of the abdominal cavity, lesions of mesentery lymph nodes, retroperitoneal tumors.
Treatment of aortic aneurysm
With an asymptomatic non-progressive course, aortic aneurysms are limited to dynamic observation by a vascular surgeon and X-ray control. To reduce the risk of possible complications, hypotensive and anticoagulant therapy, lowering cholesterol levels are carried out.
Surgical intervention is indicated for abdominal aortic aneurysms with a diameter of more than 4 cm; thoracic aortic aneurysms with a diameter of 5.5-6.0 cm or with an increase in smaller aneurysms by more than 0.5 cm in six months. In case of rupture of an aortic aneurysm, the indications for emergency surgery are absolute.
Surgical treatment of an aortic aneurysm consists in excision of an aneurysmally altered portion of the vessel, suturing of the defect or its replacement with a vascular prosthesis. Taking into account the anatomical localization, resection of the abdominal aortic aneurysm, thoracic aorta, aortic arch, thoracoabdominal part of the aorta, and the subrenal aorta is performed.
In hemodynamically significant aortic insufficiency, resection of the ascending thoracic aorta is combined with prosthetics of the aortic valve. An alternative to open vascular intervention is endovascular prosthetics of an aortic aneurysm with the installation of a stent.
Prognosis and prevention
The prognosis of an aortic aneurysm is mainly determined by its size and concomitant atherosclerotic lesion of the cardiovascular system. In general, the natural course of an aneurysm is unfavorable and is associated with a high risk of death from aortic rupture or thromboembolic complications. The probability of rupture of an aortic aneurysm with a diameter of 6 cm or more is 50% per year, smaller diameter – 20% per year. Early detection and planned surgical treatment of aortic aneurysms is justified by low intraoperative (5%) mortality and good long-term results.
Preventive recommendations include blood pressure monitoring, organization of a proper lifestyle, regular follow-up by a cardiologist and angiosurgeon, drug therapy of concomitant pathology. Persons from risk groups for the development of aortic aneurysm should undergo screening ultrasound examination.