Aortic Dissection

 

The aorta is the biggest artery in our body. It originates from the heart, makes a U-turn in the upper chest and ends around the umbilical area, with branches of artery supplying the whole body with oxygenated blood. Therefore, conditions that affect the aorta may affect the blood supply to certain organs, depending on which part of the aorta is involved. 

The wall of the aorta comprises an inner, middle and outer layer. It is typically thick and elastic enough to withstand the pressure of oxygenated blood flowing from the heart to the different parts of the body.

Disease in the aorta can cause narrowing or, more commonly, abnormal dilatation of the artery. However, the most dreaded disease which affects the aorta is aortic dissection, a rare but is potentially life threatening condition. 

Aortic dissection is caused by disruption of the aorta wall, which allows blood to flow between the layers of the blood vessel wall. The origins of major branches from the aorta at the site of the dissection may be affected, thus compromising blood flow to the respective major organs. Death, heart attack or stroke may ensue if arteries to the heart or brain are affected.

Aortic dissection is usually associated with high blood pressure or conditions that weaken the wall of the blood vessel, such as Marfan’s syndrome. Rarely, it can also happen during pregnancy in normal women.

The symptoms of acute aortic dissection are usually dramatic with sudden, severe ripping chest or back pain. The pain may travel if there is extension of the dissection.

Related symptoms may occur as a consequence of reduced blood flow to various parts of the body, or due to the pressure exerted on vital organs by an enlarging blood clot, such as:

Other symptoms, depending on whether the origins of major arteries are involved, include heart attack, stroke, heart failure or shock.

Aortic dissection is a dreaded diagnosis. One should ensure adequate control of high blood pressure and seek help early when symptoms arise.

Aortic dissection is due to the splitting of the layers of the wall (dissection) of the aorta, the main artery in the body and is usually related to very high blood pressure. The pain is usually described as a tearing pain in the chest, radiating to the back. The dissection may extend into the origin of the aorta and block off one or more of the coronary arteries, leading to a heart attack. Aortic dissection is a medical emergency.

Aortic dissection has the following risk factors:

Patients with severe chest or back pain, especially those suffering from high blood pressure, may be suspected of having aortic dissection. 

Chest X-ray showing widening of the tissue in the middle of the chest is suggestive of aortic dissection. However, a Computed Tomography (CT) scan, Magnetic Resonance Imaging (MRI) or ultrasound (or echocardiogram) is usually needed to confirm the diagnosis.

The most important treatment of aortic dissection is to reduce the blood pressure to prevent further extension of the dissection. The location of the tear in the aortic wall (or type of aortic dissection) and risk of aortic rupture will determine whether doctors will treat aortic dissection with surgery or medications.

Emergency surgery is required when the tear occurs in the ascending aorta or the portion of the aorta closest to the heart (type A aortic dissection), as arteries to the heart and brain are usually involved. Surgery is required only if there is persistent pain or worsening dissection. 

The risk of death increases by one per cent for each hour that passes after the aorta has torn and has not been treated. Within 48 hours, 50 per cent of the patients will die. The goal of surgery is to prevent death from exsanguination from the rupture of the aorta, stroke, heart attack and severely leaking heart valve.

In open heart surgery, surgeons will replace the damaged portion of the aorta with a synthetic tube graft. The adjacent structures of the heart may also need to be treated if the condition affected the:

The former can be preserved by repair or replaced with prosthetic valves, whilst the latter can be preserved by reimplanting them onto the graft or through additional coronary bypass surgery.

Endovascular stent grafting, a minimally invasive surgery, may be recommended for suitable patients.

Usually, oral or intravenous medications will be recommended instead of surgery, in case of tears involving the descending aorta (type B aortic dissection). The goal is to aggressively reduce and control high blood pressure.

Dissection of other parts of the aorta are usually stabilised medically first. Medications for aortic dissection may be through oral medications, or intravenous medications, if the initial blood pressure is high or not controlled with oral medications. 

Even after surgery, aortic dissection patients will need to continue taking oral medications to control their heart rate and reduce their high blood pressure.