Aortic Aneurysm and Aortic Dissection
Disease Description
An aortic aneurysm is an abnormal dilation of the main artery of the body, in which the diameter of the aorta increases more than twofold. According to its anatomical location, aortic aneurysms are classified into aneurysms of the ascending aorta, the aortic arch and descending aorta, and abdominal aortic aneurysms.
Aortic dissection is a life-threatening condition that occurs after damage and rupture of the inner layer of the aortic wall, allowing blood to penetrate between the layers of the vessel wall. Aortic dissections are also classified by the site of onset into dissections of the ascending aorta and dissections of the descending thoracic aorta. Dissections of the descending thoracic aorta often extend into the abdominal aorta.
Causes of the Disease
The causes of aortic aneurysm formation include systemic atherosclerosis, genetically determined connective tissue disorders associated with weakness of the aortic wall (such as Marfan syndrome, Ehlers–Danlos syndrome, and others), arterial hypertension, and infectious diseases.
Blood pressure exerts continuous force on the weakened aortic wall, leading to progressive enlargement of the aneurysm and eventually to rupture. Rupture of an aortic aneurysm results in massive arterial bleeding outside the vessel, hemorrhagic shock, and death.
The most common causes of aortic dissection are genetically determined weakness of the vessel wall and traumatic injury (e.g., motor vehicle accidents). After rupture of the inner layer of the aorta, blood under pressure separates the layers of the vessel wall over a significant length, which may lead to rupture of the aorta and impaired blood supply to organs at and below the level of dissection.
Symptoms
Patients with an uncomplicated aortic aneurysm usually have no specific complaints. In the vast majority of cases, aortic aneurysms are detected incidentally during routine medical examinations or during evaluation for other conditions. Some patients with abdominal aortic aneurysms may notice a pronounced pulsation in the abdomen.
When complications such as aneurysm rupture develop, patients experience characteristic symptoms including severe pain in the back, abdomen, or lower back, accompanied by extremely low blood pressure, pale skin, profuse sweating, confusion, and possible loss of consciousness.
In aortic dissection, pain occurs suddenly, often after a triggering factor (though sometimes without one). The pain is localized to the chest, back, or between the shoulder blades, is severe and sharp, and is accompanied by low blood pressure, intense fear of death, and loss of consciousness.
Diagnosis
Aortic aneurysms are most commonly detected during abdominal ultrasound examinations, echocardiography (cardiac ultrasound), chest X-ray, or multislice computed tomography performed for other medical indications.
For suspected aortic dissection, contrast-enhanced multislice computed tomography is considered the diagnostic gold standard.
Treatment
The main indication for surgical treatment of an aortic aneurysm is its size. When the diameter of a thoracic or abdominal aortic aneurysm reaches 50 mm, consultation with a specialist is recommended to determine surgical indications and select the optimal treatment method. For aneurysms of the ascending aorta, surgical intervention is indicated at 55 mm (or 50 mm in patients with genetically determined aortic wall weakness). For aneurysms of the aortic arch and descending thoracic aorta, the threshold is 55 mm.
Indications for surgical treatment of aortic dissection depend on multiple factors, including the duration of the dissection, its extent, and the presence of impaired blood supply to organs and tissues at or below the level of dissection.
Two main treatment approaches are used for aortic pathology:
1. Endovascular Treatment
This is a minimally invasive approach used to treat aneurysms of the aortic arch, descending thoracic aorta, or abdominal aorta (this method is currently not applicable for aneurysms or dissections of the ascending aorta). The aneurysm itself is not removed; instead, a special device called a stent graft is placed inside the aorta. The stent graft expands and is fixed within the aneurysm, reinforcing the aortic wall and excluding the aneurysm from the bloodstream.
In cases of aortic dissection, the stent graft is placed at the site of the initial tear, sealing the entry point of the dissection. The procedure is performed through a small (approximately 2 cm) incision in the groin, avoiding major surgery such as opening the chest or abdominal cavity. These procedures are typically performed without general anesthesia; the patient remains conscious and breathes independently.
However, not all patients are suitable candidates for endovascular treatment. The method requires specific anatomical characteristics of the aorta, which limits its applicability.
2. Open Surgery
Open aortic replacement allows treatment of aneurysms or dissections of the aorta at any location. The procedure is performed under general anesthesia. During surgery, the affected segment of the aorta is removed and replaced with a special synthetic graft.
The main limitation of this approach is its invasiveness, as not all patients can tolerate such major surgery.
Treatment Prognosis
With the natural course of the disease and no surgical intervention, the risk of aortic aneurysm rupture and patient survival depend on aneurysm size. Once an aneurysm reaches 5 cm, the annual rupture risk is approximately 1%, increasing to 10–30% with further enlargement.
In the event of aneurysm rupture, mortality exceeds 50% within the first 24 hours. With planned surgical treatment, the prognosis is relatively favorable. Mortality following elective open abdominal aortic replacement is approximately 5.5%, and repeat open surgery is rarely required. After elective endovascular repair of an abdominal aortic aneurysm, mortality is about 1.5%, although repeat endovascular interventions are more common than after open surgery. Long-term follow-up by a cardiovascular surgeon is mandatory.
In aortic dissection, prognosis depends on the location of the dissection. For dissections of the ascending aorta, non-operative mortality is 1–2% per hour during the first hours (up to 50% within the first 48 hours), whereas emergency surgery reduces one-month mortality from 90% to approximately 30%.
For dissections of the descending aorta without impaired blood supply to organs and tissues, the prognosis is favorable. Conservative therapy, patient stabilization, and preparation for planned surgical treatment are possible. Mortality for planned treatment of descending aortic dissection is approximately 8% with endovascular repair and ~37% with open thoracic aortic replacement. Postoperative outcomes are generally favorable, with mandatory long-term follow-up by a cardiovascular surgeon.