Aortic arch aneurysm is a diffuse or local expansion of the aortic lumen in the segment between its ascending and descending parts, exceeding the normal diameter of the vessel. Disease can manifest itself by shortness of breath, cough, dysphagia, hoarseness of voice, swelling and cyanosis of the face, swelling of the cervical veins, which is associated with compression of nearby organs. Diagnostic tactics include chest radiography, EchoCG and ultrasound of the thoracic aorta, aortography, CT and MRI. The treatment consists in resection aortic arch aneurysm in IR conditions with the installation of an allograft or endoluminal prosthetics of the aneurysm with a special endoprosthesis.
I71.2 Thoracic aortic aneurysm without mention of rupture
Depending on the level of localization, aneurysms of the aortic root and sinuses of the Valsalva, ascending aorta, aortic arch, descending aorta, abdominal aorta are distinguished. Quite often in cardiology and cardiac surgery there are combined lesions of adjacent segments of the aorta. Thus, aortic arch aneurysm are rarely found in isolation; in most cases they are a continuation of an aneurysmal expansion of the root or ascending aorta.
The aortic arch is usually called the part of the aorta located between its ascending and descending sections. The aortic arch passes between the pulmonary arteries and wraps around the left main bronchus. Three large vascular branches depart from the aortic arch – the brachiocephalic trunk, the left common carotid artery and the left subclavian artery.
According to autopsies, thoracic aortic aneurysms occur in 0.9-1.1% of cases, 3-7 times more often in men. Of these, aortic arch aneurysm account for about 18.9% of cases. The mortality rate within 3 years after the detection of an aneurysm is 35%, and after 5 years reaches 54-65%.
The causes and mechanisms of development of aortic arch aneurysm do not differ from those of aneurysms of other localizations. Innate risk factors include:
- hereditary connective tissue diseases that contribute to aortic wall weakness – Marfan disease, fibrous dysplasia, Ehlers—Danlos syndrome
- cystic media
- necrosis congenital tortuosity of the aortic arch
- coarctation , etc .
Among the acquired states , the leading role belongs to:
- inflammatory aortic lesions – specific and nonspecific aortitis in rheumatism, syphilis, tuberculosis, mycoses, bacterial infection, Takayasu disease
- non-inflammatory degenerative processes (atherosclerosis of the thoracic aorta, etc.)
- chest injuries. As a result of chest injuries, post-traumatic aortic arch aneurysm may form. From the moment of injury to the development of an aortic arch aneurysm can take a long time (from several months to 20 years).
- iatrogenic factors. With the development of vascular surgery, aortic arch aneurysm caused by defects in grafts and suture material, including poststenotic aneurysms, are increasingly common.
Persistent arterial hypertension contributes to the weakening of the tone of the aortic walls and the formation of an aneurysmal sac. The age over 60 years, male sex, and the presence of an aneurysm in family members are considered to be independent mechanisms of the development of an aortic arch aneurysm.
Hemodynamic and mechanical factors play a role in the pathogenesis of aortic arch aneurysm, in addition to inflammatory and degenerative processes. The features of hemodynamics in the thoracic aorta are the high blood flow rate, the steepness of the pulse wave and its shape. In addition, the thoracic aorta has the most functionally stressed segments – the root, isthmus and diaphragm. Therefore, an increase in blood pressure or mechanical injury easily leads to tearing of the inner lining of the aortic wall with the formation of a subintimal hematoma, and subsequently an aneurysm.
Aneurysms of inflammatory origin are characterized by the phenomena of periaortitis, thickening of the outer shell and the intimate layer of the aorta, productive inflammation with destruction of the elastic and muscular framework of the aortic wall.
Symptoms of aortic arch aneurysm
Aortic arch aneurysm of medium and large size leads to compression of adjacent anatomical structures, which determines the features of the clinical course of pathology. The pressure of the aneurysmal sac on the surrounding tissues and stretching of the aortic nerve plexuses is accompanied by pulsation in the chest, pain behind the sternum with irradiation into the neck, shoulder, back. As a rule, the pain has a persistent, burning character and is not stopped by taking nitrates.
Dry, painful cough, shortness of breath and stenotic breathing appear with compression of the bronchi and trachea. When an aneurysm squeezes the aortic arch of the recurrent nerve, laryngeal paresis occurs (dysphonia and hoarseness of the voice); compression of the esophagus is accompanied by dysphagia. The development of the syndrome of the superior vena cava is characterized by headaches, swelling of the face and upper half of the trunk, suffocation, cyanosis, swelling of the veins of the neck, hyperemia of the sclera. When the sympathetic pathways are squeezed, Gorner’s syndrome develops, which is expressed in constriction of the pupils, partial ptosis of the eyelids, anhidrosis, etc.
In some cases, this disease is recognized only in connection with its rupture. This complication may be accompanied by mediastinal hemorrhage, hemothorax, bleeding into the esophagus, hemoptysis and pulmonary bleeding. Massive bleeding is accompanied by sharp pain, pallor, loss of consciousness, threadlike pulse and, as a rule, quickly leads to death. In addition to rupture, aortic arch aneurysm may be complicated by thromboembolism of the arteries of the large circulatory circle, including cerebral ones, leading to the development of stroke.
Diagnosis of aortic arch aneurysm
Diagnosis of aortic arch aneurysm is based on clinical data, results of radiography, aortography, ultrasound angioscanning, CT and MRI.
During external examination, one may pay attention to the increased pulsation of the aortic arch in the jugular notch, as well as the visible protrusion of the aneurysmal sac in the sternum area. It is important to have a history of syphilis, chest injury, nonspecific aortoarteritis, etc. In some cases, the appearance of patients with Marfan syndrome allows to suspect an aortic arch aneurysm: tall stature, thinness, long arms, arachnodactyly, funnel-shaped chest, kyphoscoliosis, increased weakness of the ligamentous apparatus of the joints.
- X-ray diagnostics. Polypositional chest X-ray reveals the shadow of the expanded aortic arch and the expansion of the vascular bundle. Calcification of the aneurysm walls is often determined. Radiography of the esophagus and stomach allows you to detect the displacement of the esophagus and stomach cardia. Invasive radiopaque aortography is mainly used to assess blood flow in the branches of the aorta.
- Sonography. The leading role in the recognition of aortic arch aneurysms belongs to ultrasound: echocardiography (transthoracic, transesophageal EchoCG), ultrasound and duplex scanning of the thoracic aorta. This method is indispensable for determining the diameter of the aorta, the presence of dissection, blood clots in the aneurysmal sac.
- Tomography. CT of the thoracic aorta with contrast makes it possible to visually identify a baggy or fusiform expansion of the aortic lumen, the presence of thrombotic masses, dissection, paraaortic hematoma, foci of calcification. Differential diagnosis of aortic arch aneurysm should be performed with lung and mediastinal tumors.
Treatment of aortic arch aneurysm
Conservative wait-and-see tactics can be used for isolated aneurysms of small size that do not cause clinical symptoms. In this case, patients are prescribed antihypertensive drugs, adrenoblockers, statins. At the same time, every six months, patients are shown dynamic observation, including a cardiologist’s examination, EchoCG, CT or MRI. Surgical treatment is subject to aortic arch aneurysm over 5 cm in diameter, occurring with pain or compression syndrome, as well as aneurysms complicated by dissection, rupture and thrombosis.
- Open operation. Radical treatment consists in resection of an aortic arch aneurysm. The essence of the operation is the excision of an aneurysm with the replacement of the aortic defect with an allograft, the imposition of anastomoses of the brachycephalic trunk, the left common carotid and left subclavian arteries with a vascular prosthesis. The operation is performed in conditions of artificial blood circulation with the protection of the myocardium and brain from ischemia by hypothermia. Surgical mortality in this type of surgery is about 5-15%. Long-term results after resection of an aortic arch aneurysm are good.
- Endovascular intervention. In addition to open surgery for aortic arch aneurysm, closed endovascular prosthetics of the aneurysm is used. In this case, a special endoprosthesis is inserted into the aneurysm lumen with the help of a guide and fixed above and below the aneurysmal sac. In some cases, if there are absolute contraindications to performing radical surgery, palliative intervention is performed, which consists in wrapping the aneurysm with synthetic tissue in case of a threatening rupture.
In case of refusal of treatment, the prognosis is unfavorable: about 60% of patients die within 3-5 years from aneurysm rupture, coronary artery disease, stroke. The prognosis is aggravated with an aneurysm size of more than 6 cm, concomitant hypertension, post-traumatic genesis of an aortic arch aneurysm.