Treatment of Aortic Dissection: Vascular Surgical and Endovascular Therapy for Type A and Type B

A blood vessel is essentially a tube through which blood flows. It is formed by the vessel wall. The wall of larger blood vessels consists of three layers of tissue stacked on top of one another:

• inner layer (intima),
• middle layer (media), and
• the outer layer (adventitia)

The hollow space inside a blood vessel is called the lumen.

A separation of the vascular wall layers occurs when the inner layer tears, but the outer layer remains intact. Blood then leaks from the lumen through the tear into the space between the two layers.

Due to the high pressure inside the aorta, more and more blood enters the space between the layers. As a result, the layers separate over long stretches and can form an abnormal gap. This can completely occlude the actual lumen.

The intima usually cannot withstand the high pressure and tears again at another location. This allows blood to flow back into the aorta.

Risk factors for the development of an aortic dissection include atherosclerosis and structural weakness of the media (media degeneration). Such structural weakness is often seen in patients with congenital heart valve abnormalities or connective tissue disorders. Examples of such conditions include Marfan syndrome and Ehlers-Danlos syndrome.

Other risk factors include advanced age and high blood pressure. In addition, traumatic events can cause an aortic dissection, such as injury to the vessel wall during a catheterization procedure.

The symptoms depend on the location and extent of the dissection. Some patients with chronic aortic dissection have no symptoms at all. In extreme cases, however, a rupture of the aorta can lead to sudden cardiac death.

Typically, an acute aortic dissection presents with a sudden-onset, severe, stabbing, or tearing pain in the chest. This pain may radiate to the shoulder blades and back.

Depending on the section of the vessel affected, additional symptoms may occur, such as

• abdominal pain,
• signs of paralysis,
• acute kidney failure, or
• neurological deficits.

Blood loss can lead to symptoms of shock, such as

• rapid pulse,
• a drop in blood pressure,
• and impaired consciousness.

Depending on the location of the tear and the extent of the bleeding, several categories can be distinguished. The DeBakey classification defines three types of aortic dissections:

• DeBakey I: A tear in the ascending aorta (aorta ascendens); the hemorrhage extends beyond the aortic arch.
• DeBakey II: The tear is also in the ascending aorta (aorta ascendens), but the re-entry of the hemorrhage occurs within the ascending aorta.
• DeBakey III: The entry and re-entry are located in the descending aorta (aorta descendens).

A further development of this classification is the Stanford classification. Based solely on the location of the entry, it distinguishes between only two types:

• Stanford A (= DeBakey I and II): Tear in the ascending aorta,
• Stanford B (= DeBakey III): A tear in the descending aorta.

The location of the tear is critical in determining the patient’s risk and, consequently, the treatment. For this reason, specialists in aortic dissection primarily use the Stanford classifications to assess the condition.

If an aortic dissection is suspected, imaging techniques can reveal bleeding into the aorta. Initial indications may include

• a chest X-ray showing the chest and its organs, as well as
• an ultrasound examination (sonography) of the abdominal cavity

. Transesophageal echocardiography (TEE, an ultrasound examination via the esophagus) allows for a precise assessment of the aorta near the heart as well as the descending aorta.

Doppler imaging also allows for differentiation between the normal and “false” lumens; entry and re-entry can usually be identified. Contrast-enhanced computed tomography (CT) provides a clear depiction of the extent of the aortic dissection and its relationship to adjacent vessels. Magnetic resonance imaging (MRI) is also a reliable method for diagnosing aortic dissection. Angiography (a method for visualizing blood vessels) can also provide important insights.

Endovascular therapy now plays a central role in the treatment of aortic dissection, particularly in Type B dissection. In this procedure, a stent graft is inserted into the affected portion of the aorta via a minimally invasive approach through the femoral artery. The goal is to occlude the false lumen and redirect blood flow back through the true lumen. This helps stop the progression of the dissection along the aortic wall and promotes thrombosis of the false lumen.

In cases of acute Type A dissection, surgery generally remains the treatment of choice to replace the ascending aorta and, if necessary, the aortic valve. In specific cases, however—such as in patients with an elevated surgical risk—endovascular therapy may also be considered. This method is particularly helpful in cases of complicated or postoperative dissections, when repeat open surgery would carry high risks.

The selection of the appropriate procedure is made through an interdisciplinary approach in close coordination between vascular surgery, radiology, and cardiology. The location of the dissection, the origin of the left subclavian artery, and the patient’s overall condition play a decisive role in this decision. Modern imaging, particularly computed tomography, enables precise planning and monitoring of the procedure.

In the long term, endovascular therapy not only stabilizes the affected segment of the vessel but also preserves the blood supply to vital organs. Regular follow-up examinations are necessary to detect progression of the dissection or aortic rupture at an early stage.

The location of the tear is critical for determining the treatment.

An acute Stanford Type A dissection must be considered an emergency and should be treated surgically as quickly as possible. During surgery, the affected section of the vessel is typically removed and replaced with a vascular prosthesis.

The implantation of vascular prostheses into the aorta carries a relatively high risk for the patient. For this reason, a Stanford Type B dissection is initially managed with a watch-and-wait approach. This means that the physician monitors the progression of the dissection. Surgery is only performed if the situation worsens—for example, in the event of

• imminent occlusion of arterial branches,
• a rapidly increasing vessel diameter, or
• imminent aortic rupture,

will the doctor initiate treatment.

Specialists treat complications such as occluded arterial branches caused by aortic dissection using catheters. Stent implantation can stabilize the vessel wall and, if necessary, create an artificial re-entry. This reduces pressure in the “false lumen” and thereby lowers the risk of rupture.

Pain management and blood pressure reduction are achieved with medication.

What are the symptoms of an aortic dissection, and when is it life-threatening?
An aortic dissection usually occurs suddenly and is accompanied by severe, tearing pain in the chest or back. It is caused by a tear in the aorta, allowing blood to enter the space between the layers of the aortic wall. An acute Type A dissection involving the ascending aorta is particularly dangerous because it can quickly lead to aortic rupture or occlusion of major arteries. A Type B dissection in the descending aorta can also become life-threatening if it spreads to other sections or causes complications.

How is an aortic dissection diagnosed?
If an aortic dissection is suspected, prompt imaging studies are crucial. Computed tomography (CT) is the standard procedure for visualizing the extent of the dissection and the false lumen. ECG, transesophageal echocardiography, and MRI also provide valuable information regarding involvement of the ascending aorta or other vessels. In vascular surgery, physicians also assess whether the tear in the aortic wall is causing impairment of the aortic valve or the blood supply to vital organs.

What classification system is used to assess an aortic dissection?
The DeBakey and Stanford classifications are used to categorize dissections. Stanford types A and B refer to the location of the tear: Type A affects the ascending aorta, while Type B affects the descending aorta. The DeBakey classification additionally distinguishes between Types I, II, and III, depending on the length and extent of the dissection. These classifications are crucial for treatment planning, as they determine whether surgery or endovascular therapy is required.

How is an aortic dissection treated?
Treatment depends on the type and severity of the dissection. For Type A, immediate surgery is usually performed to replace the affected portion of the aorta and, if necessary, the aortic valve. For Type B, the initial focus is on medical therapy with beta-blockers and blood pressure control to prevent the dissection from progressing. In many cases, endovascular therapy or a vascular prosthesis is implanted later to stabilize the vessel wall. The procedure can be performed either surgically or using minimally invasive techniques and requires close follow-up care in the vascular surgery department.

What complications can occur during the course of the disease?
Complications arise if the dissection progresses or if the false lumen becomes thrombosed. An aortic dissection can lead to bleeding, aortic rupture, a tear in the aorta, or impaired blood flow to the kidneys and other organs. In some patients, the condition becomes chronic and may recur later. An acute Type B dissection can extend along the entire length of the aorta or affect the origin of the left subclavian artery. Regular follow-up examinations using computed tomography and ultrasound help to detect such risks early on.

What should be kept in mind after surgery or endovascular treatment?
After surgery or stent implantation, patients must be monitored regularly to rule out the progression of the dissection along the vessel wall. Medication therapy with beta-blockers and antihypertensives is usually continued indefinitely. It is also important to avoid physical exertion and to closely monitor blood pressure. An interdisciplinary team comprising vascular surgeons, radiologists, and cardiologists provides follow-up care to detect complications—such as a recurrent aortic dissection or impaired blood supply—in a timely manner.