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Aneurysm of the thoracic aorta
Last reviewed: 23.04.2024
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Aneurysms of the thoracic aorta account for a quarter of the aortic aneurysm. Men and women suffer equally often.
Approximately 40% of the thoracic aortic aneurysms develops in the ascending thoracic aorta (between the aortic valve and the brachiocephalic trunk), 10% in the aortic arch (including the brachiocephalic trunk, carotid and subclavian arteries), 35% in the descending thoracic aorta (distal to the left subclavian artery), 15% - in the upper abdominal cavity (like thoracoabdominal aneurysms).
Causes of aneurysms of the thoracic aorta
Most aneurysms of the thoracic aorta result from atherosclerosis. Risk factors for both conditions include prolonged arterial hypertension, dyslipidemia and smoking. Additional risk factors for aneurysms of the thoracic aorta include the presence of aneurysms of other localization and older age (the maximum incidence is 65-70 years).
Congenital connective tissue diseases (eg Marfan syndrome, Ehlers-Danlo syndrome) cause cystic necrosis of the middle shell - a degenerative change that leads to aneurysm of the thoracic aorta complicated by aortic dissection and an extension of the proximal aortic and aortic valve causing aortic re-hydration . Marfan syndrome causes 50% of cases of such extensions, but cystic necrosis of the middle shell and its complications can develop in young people even in the absence of congenital anomalies of connective tissue.
Infected (mycotic) aneurysms of the thoracic aorta arise as a result of hematogenous spread of the pathogen in systemic or local infections (eg, sepsis, pneumonia), lymphogenous penetration (eg, tuberculosis), as well as direct spread from a nearby foci (eg, osteomyelitis or pericarditis). Infectious endocarditis and tertiary syphilis are rare causes. Aneurysms of the thoracic aorta develop with certain connective tissue diseases (eg giant cell arteritis, Takayasu arteritis, Wegener's granulomatosis).
A dull chest trauma causes pseudoaneurysms (extramural hematomas that form due to rupture of the aortic wall).
Aneurysms of the thoracic aorta can exfoliate, decay, destroy adjacent structures, lead to thromboembolism or rupture.
Symptoms of an aneurysm of the thoracic aorta
Most aneurysms of the thoracic aorta remain asymptomatic until complications develop (for example, aortic regurgitation, delamination). Compression of adjacent structures can cause chest or loin pain, coughing, wheezing, dysphagia, hoarseness (due to compression of the left recurrent laryngeal or vagus nerve), chest pain (due to compression of the coronary artery), and upper vena cava syndrome. Erosive breakthrough of an aneurysm in the lungs causes hemoptysis or pneumonia. Thromboembolism can lead to a stroke, abdominal pain (due to mesenteric embolism), or limb. If the aneurysm of the thoracic aorta ruptures, if there is no instantaneous death, intense pain in the chest or lower back, arterial hypotension or shock occurs. Bleeding usually occurs in the pleural or pericardial cavity. If there is aorto-esophageal fistula before the rupture, massive vomiting is possible with blood.
Additional symptoms include Horner's syndrome due to compression of sympathetic ganglia, palpable stress of the trachea with each heartbeat (tracheal spurt) and deviation of the trachea. The visible or palpable pulsation of the chest wall, sometimes more noticeable than the apical push of the left ventricle, is unusual, but possible.
Syphilitic aneurysms of the root of the aorta classically lead to aortic regurgitation and inflammatory stenosis of the coronary arteries, which can manifest as pain in the chest due to myocardial ischemia. Syphilitic aneurysms do not exfoliate.
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Diagnosis of aneurysms of the thoracic aorta
Usually a suspicion of an aneurysm of the thoracic aorta arises when chest radiography reveals an enlarged mediastinum or an extension of the aortic shadow. These data or clinical manifestations that raise suspicion of an aneurysm are confirmed by three-dimensional imaging studies. KTA allows to determine the size of an aneurysm, the proximal and distal levels of its distribution, to detect blood leakage and to identify another pathology. MRA provides similar data. Transesophageal echocardiography (TEE) helps to determine the size and prevalence and to detect leakage of blood in the ascending (but not descending) part of the aorta.
TSE is especially important for the detection of aortic dissection. Contrast angiography provides a better image of the arterial lumen, but does not provide information on structures located outside the aortic lumen, is invasive, creates a significant risk of renal embolism with atheromatous plaque, embolism in the lower extremities, and nephropathy due to contrast. The choice of a visualization study is based on the availability and experience of the physician, however, if suspicion of a rupture is indicated, immediate TEE or KTA (depending on availability) is indicated.
Dilation of the root of the aorta or unexplained aneurysms of the ascending part of the aorta is an indication for a serological study of syphilis. If there is a suspicion of a mycotic aneurysm, bacterial and fungal blood cultures are obtained.
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Treatment of aneurysms of the thoracic aorta
Treatment includes surgical prosthetics and control of hypertension, if any.
Ruptured aneurysms of the thoracic aorta without treatment are always fatal. They require immediate surgical intervention, as well as an aneurysm with leakage of blood and are in a state of acute exfoliation or acute valvular regurgitation. Surgical intervention involves median sternotomy (for an aneurysm of the ascending part and aortic arch) or left-sided thoracotomy (for aneurysms of the descending section and thoracoabdominal aneurysms), subsequent excision of the aneurysm and installation of a synthetic prosthesis. Catheter endovascular stenting (endoprosthesis) in the descending aorta is in the process of being studied as a less invasive alternative to open surgical intervention. In emergency surgical treatment, 1-month mortality is approximately 40-50%. The survivors have a high incidence of serious complications (eg, kidney failure, respiratory failure, severe pathology of the nervous system).
Surgical treatment is preferable at large (diameter> 5-6 cm in the ascending part,> 6-7 cm in the descending part of the aorta, and for patients with Marfan syndrome> 5 cm for any location), and also rapidly increasing (> 1 cm / year) aneurysms. Surgical treatment is also prescribed for aneurysms, accompanied by clinical symptoms, post-traumatic or syphilitic aneurysms. With syphilitic aneurysms after surgery, intramuscularly prescribed benzylpenicillin for 2.4 million units per week for 3 weeks. If a patient has an allergy to penicillin, use tetracycline or erythromycin 500 mg 4 times a day for 30 days.
Although surgical treatment of intact aneurysms of the thoracic aorta provides good results, mortality may still exceed 5-10% within 30 days and 40-50% in the next 10 years. The risk of death increases with complicated aneurysms (for example, localized in the arch of the aorta or thoraco-abdominal section), and also if patients have IHD, advanced age, aneurysms with clinical symptoms or a history of renal insufficiency. Perioperative complications (such as stroke, spinal injury, renal failure) occur in approximately 10-20% of cases.
With asymptomatic aneurysms and absence of indications for surgical treatment, the patient is monitored, carefully controlled by blood pressure, prescribed b-blockers and other antihypertensives as needed. Requires CT scan every 6-12 months and frequent medical examinations to identify symptoms. Quitting is mandatory.
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Prognosis for aneurysm of the thoracic aorta
Aneurysms of the thoracic aorta increase by an average of 5 mm per year. Rapid expansion risk factors include a large aneurysm size, its location in the descending part of the aorta and the presence of clots in the organ. On average, with aneurysm rupture, its diameter is 6 cm for an aneurysm of the ascending department and 7 cm for an aneurysm of the descending department, but in patients with Marfan's syndrome the rupture can occur at smaller sizes. Survival of patients with large aneurysms of the thoracic aorta without treatment is 65% within 1 year and 20% within 5 years.