aortic dissection Aortic dissection (AD), also known as dissecting aortic aneurysm, is a severe cardiovascular emergency caused by a tear in the intimal layer of the aortic wall, allowing blood to enter the media layer and form a dissection hematoma. This condition gradually leads to the separation and dissection of the intima and media of the aorta. The aortic lumen at the site of the lesion is divided by the intimal flap into true and false lumens, which may or may not communicate, potentially leading to thrombus formation as blood flows between them.

Aortic dissection (AD), also known as dissecting aneurysm of the aorta, is a severe cardiovascular emergency characterized by a tear in the intimal layer of the aortic wall, allowing blood to enter the middle layer of the artery, forming a dissecting hematoma, and gradually causing separation and dissection of the intimal and medial layers of the aorta. The affected area of the aorta is divided into true and false lumens by the intimal flap, with or without communication between the two lumens, potentially leading to thrombus formation.

Clinical Staging

Based on the duration of the disease, aortic dissection can be classified into acute phase (≤14 days), subacute phase (15 to 90 days), and chronic phase (>90 days).

Anatomical Classification

DeBakey Classification

Type I: Primary tear located in the ascending aorta or aortic arch, involving most or all of the thoracic ascending aorta, aortic arch, descending thoracic aorta, and abdominal aorta.

Type II: Primary tear located in the ascending aorta, involving the ascending aorta, and occasionally the aortic arch.

Type III: Primary tear located distal to the left subclavian artery, with the dissection limited to the descending thoracic aorta categorized as type IIIa, and involving the abdominal aorta as type IIIb.

Stanford Classification

Dissection involving the ascending aorta is classified as Stanford type A, while involvement limited to the descending thoracic aorta and its distal portion is classified as Stanford type B.

Sun's Refined Classification

An elaboration of the Stanford classification, providing a more detailed classification of aortic dissection to reflect the degree of pathology and prognosis, guiding clinicians in developing personalized treatment plans based on the patient's condition. This classification is widely used in China.

Atypical Variants

Intramural hematoma (IMH)

Distinguished from typical aortic dissection, IMH lacks an intimal tear but can progress to form aortic dissection. The course of the two conditions is similar, and the treatment principles are largely the same.

Penetrating atherosclerotic ulcer

A focal lesion located on the luminal surface of the aortic wall. Its natural course varies, and it can easily lead to aortic dissection or perforation.

Due to various factors such as aging, the compliance of the aortic vessel wall may decrease, leading to reduced vascular elasticity. This, in turn, increases the pressure on the vessel wall from the blood flow, further damaging the vessel wall and causing a tear in the intimal layer, resulting in aortic dissection.

Most patients experience the abrupt onset of severe chest pain. The nature of the pain is often described as cutting, stabbing, or tearing and is typically sustained and difficult to tolerate, with poor response to opioid analgesics such as morphine.

The location of the pain is related to the site of the dissection:

When the dissection affects the proximal ascending aorta, it mainly presents as anterior chest pain, while involvement of the ascending aorta and aortic arch can lead to pain in the neck, throat, and jaw.

Dissection in the descending thoracic aorta often manifests as pain in the scapular region, and dissection of the abdominal aorta can cause back, abdominal, and lower limb pain.

If the pain migrates, it indicates disease progression, and the appearance of lower limb pain suggests possible involvement of the lower limb arteries.

In patients with suspected symptoms or a high suspicion of aortic dissection, prompt admission to the cardiac intensive care unit is necessary, ensuring absolute bed rest and avoiding exertion, while ensuring regular bowel movements.

Close monitoring of the patient's vital signs and provision of oxygen support.

For patients with unstable hemodynamic parameters, preparedness for tracheal intubation should be maintained at all times.

In the case of acute Stanford type A AD, emergency surgical treatment should be performed.

For acute Stanford type B AD, after treatment with analgesics, blood pressure reduction, and reduction of ventricular contractility and heart rate, patients can generally be discharged.

Stanford type A dissection often involves the heart, and the dissection lesion easily leads to severe aortic valve insufficiency, resulting in acute left heart failure.

When the dissection lesion affects the coronary artery ostium, it can lead to myocardial infarction.

Involvement of the innominate artery or left carotid artery may lead to cerebrovascular events, with symptoms such as syncope, aphasia, drowsiness, consciousness disorders, impaired orientation, and contralateral hemiplegia.

When the dissection lesion affects the abdominal aorta or mesenteric arteries, patients may experience symptoms such as nausea, vomiting, abdominal pain, melena, or hematochezia.

Involvement of the renal artery may cause symptoms such as back pain, hematuria, oliguria, anuria, severe hypertension, or even acute renal failure.

Involvement of the lower limb arteries may lead to symptoms of pain, absence of pulses, or even acute ischemia with necrosis.

Common postoperative complications include acute respiratory failure, stroke, cerebral hemorrhage, renal failure, bleeding, infection, endoleak, and neurological complications such as paralysis or paraplegia, which should be actively managed according to the severity of the complications.

After the condition is effectively controlled, patients should continue lifelong antihypertensive treatment, with a target systolic blood pressure of <130 mmHg, with beta-blockers remaining the preferred medication, and should avoid strenuous physical activity, while undergoing regular follow-up examinations.

Some patients may experience complications such as anastomotic leaks or pseudoaneurysms after surgery, necessitating further surgical intervention. According to literature, controlling systolic blood pressure to <120 mmHg with antihypertensive treatment can significantly reduce the probability of repeat surgery in the long term.

Patients with hypertension, especially those with a long history of hypertension, familial risk factors, and concomitant immune vascular disease, should be vigilant for the occurrence of aortic dissection and undergo regular physical examinations to detect it early. The most fundamental way to prevent aortic dissection is to continuously and stably control blood pressure levels.