Pseudoaneurysm refers to the destruction of the whole structure of the arterial wall or the destruction of the middle layer of the intima, only the outer membrane of the aorta remains, and the blood spills out of the lumen and is wrapped by the surrounding tissues, and its aneurysm wall no longer has the three layers of the intact arterial wall, which is the periarterial tissue or only the outer membrane of the aorta remains.
I. Etiology and pathogenesis
All factors that can cause structural destruction of the aortic wall may be the cause of aortic pseudoaneurysm, including trauma, infection, previous cardiac aortic surgery or intervention, genetic factors, degenerative changes, immune factors, etc.
Pathophysiology
Pseudoaneurysm may compress surrounding organs, such as trachea, bronchus, lung, esophagus, superior vena cava, innominate vein, recurrent laryngeal nerve, and cervical sympathetic ganglion, resulting in corresponding clinical symptoms. Pseudoaneurysms have a slow intraluminal blood flow and are prone to the formation of appendage thrombus. If the appendage thrombus is dislodged, it may block the distal aortic branch vessels under the impact of blood flow, resulting in ischemia of organs or limbs and even necrosis. According to Laplace’s law, the pressure on the aneurysm wall is proportional to the blood pressure and the radius of the aneurysm, the higher the blood pressure and the larger the aneurysm, the greater the pressure on the aneurysm wall, and the greater the possibility of rupture of the pseudoaneurysm. Once a pseudoaneurysm ruptures, most patients die rapidly from hemorrhagic shock.
Clinical manifestations
Most patients have no specific symptoms in the early stage, and the clinical symptoms are closely related to the cause of the disease, which may be discovered accidentally during physical examination or imaging examination for other diseases. As the pseudoaneurysm increases in size, symptoms and signs of pain and compression of surrounding organs will gradually appear.
1. Pain: It is mostly dull, sometimes persistent, and may increase with breathing or physical activity. The site of pain may vary with the location of the aneurysm. Aneurysm of the ascending aorta or aortic arch may cause pain behind the sternum or in the neck. Aneurysms of the descending aorta may present with pain in the interscapular region or left chest pain. Pseudoaneurysms of the thoracoabdominal aorta and abdominal aorta may present with back pain and abdominal pain.
2. Compression symptoms: Pseudoaneurysm of the aortic arch can compress the trachea and bronchus and cause irritating cough and dyspnea, and in severe cases, it can cause pulmonary atelectasis, bronchial dilatation, bronchial and pulmonary infections, etc. Compression of superior vena cava can cause symptoms of superior vena cava obstruction syndrome: progressive head, facial and upper limb edema, which can spread to the neck and chest and back in severe cases, with purplish-red skin and varicose veins in the chest wall. Aneurysms in the arch and isthmus may compress the recurrent laryngeal nerve and cause hoarseness and choking. Compression of the cervical sympathetic ganglion may cause unilateral pupil narrowing, eyelid ptosis, eye entropion and facial anhidrosis, which are symptoms of Horner syndrome. Descending aortic aneurysm may compress the esophagus and cause difficulty in swallowing. In advanced stage, it may break into the esophagus, trachea or bronchus and cause massive vomiting of blood and blood clots, resulting in death by hemorrhagic shock or asphyxia. Abdominal aortic aneurysm can break into the duodenum and cause massive bleeding in the upper gastrointestinal tract, resulting in death.
3.Embolism: Embolism can occur in different parts of the brain, kidney, abdominal organs, limbs, etc., with corresponding symptoms of ischemia and necrosis.
IV. Diagnosis
Early signs are not obvious, and signs of compression of surrounding organs gradually appear, such as Horner syndrome, superior vena cava obstruction syndrome, signs of laryngeal return nerve compression, etc. Pseudoaneurysm of the abdominal aorta can be detected as a pulsating abdominal mass on physical examination. In case of arterial embolism in different parts of the brain, kidney, abdominal organs, limbs, etc., physical examination can find corresponding signs.
1.X-ray plain film can reveal the widening of mediastinum and the displacement of trachea and esophagus by pushing. Many asymptomatic patients find the disease by chance through X-ray plain film. For example, pseudoaneurysm rupture and bleeding can show pleural or pericardial effusion, and traumatic can also find rib or spine fracture.
CT examination can also be used for the differential diagnosis of true aneurysm, pseudoaneurysm, aortic coarctation, aortic wall hematoma, aortic ulcer and other periaortic organ tumors. The differential diagnosis of tumors in the aorta. For patients with contrast allergy or renal insufficiency, CT-enhanced examination is not suitable.
MRI can provide imaging results similar to CT, without contrast agents and avoiding ionizing radiation. MRI can evaluate aortic blood flow direction, velocity and myocardial function.
In addition to determining the size, location, scope and growth rate of pseudoaneurysm, it is very important to clarify the etiology of pseudoaneurysm. Detailed medical history and physical examination should be taken, and perfect laboratory tests should be performed to make a correct etiological diagnosis.
V. Treatment
1.Aortic root
Surgical treatment of pseudoaneurysm of the ascending aorta and aortic arch. Pseudoaneurysms in this area of the aorta can be seen in patients who have undergone previous heart and aortic surgery. Pseudoaneurysm ruptures can occur at the aortic incision, aortic cannulation site, cardiac arrest fluid perfusion needle puncture site, proximal anastomosis of coronary artery bypass graft, aorta, artificial vessel anastomosis, and other sites. Due to the mediastinal adhesions caused by the last surgery and the local anatomical changes of pseudoaneurysm formation, the open-chest procedure is likely to cause rupture of the heart, aorta or pseudoaneurysm, resulting in hemorrhage and thus threatening the patient’s life. It is safer to perform open-chest surgery under the protection of extracorporeal circulation by establishing extracorporeal circulation through femoral artery and vein before opening the chest. In patients undergoing first-time surgery, extracorporeal circulation can be established through the femoral artery-right atrium or right axillary artery-right atrium. The ascending aorta is blocked and the pseudoaneurysm is removed under cardiac infusion of stopping fluid or deep hypothermic (18°C) stopping circulation, followed by simple rupture repair or aortic root, ascending aorta, aortic arch replacement surgery and coronary artery bypass surgery, depending on the circumstances.
In case of deep hypothermia, the procedure should be performed under low-flow cerebral perfusion through the right unnamed artery or combined with left common carotid artery cannulation, which can avoid brain cell damage. Surgical procedures such as aortic root, ascending aorta, aortic arch replacement, and coronary artery bypass surgery are described in the relevant sections. Pseudoaneurysms of the aortic arch can also be treated with hybridization surgery, but the treatment is more expensive. Depending on the location of the pseudoaneurysm, the right common carotid artery or right axillary artery → left common carotid artery and left subclavian artery (pseudoaneurysm is limited to the left half of the arch) or the ascending aorta → right common carotid artery, ascending aorta → left common carotid artery “Y” type diversion is performed in the open chest. In the second stage, endoluminal repair of the aorta with a membrane stent is performed to seal the breach of the pseudoaneurysm in the aortic arch. For the few hospitals that have established hybridization operating rooms, the hybridization procedure can be completed in one stage. Femoral → cephalobrachial artery crossover should be avoided as much as possible because it is easily affected by changes in body position affecting cephalobrachial artery blood flow.
2.Pseudoaneurysm of thoracic descending aorta
There are four surgical options available.
(1) Thoracic descending aortic replacement.
(2) thoracic descending aorta with membrane stenting for endoluminal repair of the aorta.
(3) Intraoperative stenting of the thoracic descending aorta.
(4) Hybridization procedures.
Both coronary atherosclerotic heart disease and heart valve disease are common heart diseases in China. At present, there are about more than 200,000 valve surgeries each year in China, accounting for the first place in adult cardiac surgery. Although the incidence of rheumatic heart valve disease has declined significantly in recent years, the development of an aging population has caused degenerative heart valve disease in the elderly to seriously affect people’s health and quality of life, and with the aging population, changes in nutritional structure and increased awareness of the disease, the number of patients with heart valve disease combined with coronary atherosclerotic heart disease has increased year by year. Especially for men over 50 years of age and women over 55 years of age with valvular disease, the risk of combined coronary heart disease is higher, therefore, they all need to routinely undergo coronary angiography before undergoing cardiac surgery. However, performing coronary artery bypass grafting and heart valve surgery at the same time has many steps, complicated operation, long operation time, and still has high morbidity and mortality rate in the early stage of surgery.