Aortic Dissection

Aortic Aneurysm and Aortic Surgery

Aortic dissection is relatively uncommon, but it is the most frequent emergency related to the human aorta. It affects approximately three people out of every 100,000 each year, most often men with high blood pressure in their 60s and 70s.

The aorta is the major blood vessel that carries blood from the heart to the rest of the body. It is made up of three layers. These layers provide the integrity essential for the aorta to withstand the pressure of the blood pumped through it.

An aortic dissection occurs when there occurs a tear in the innermost layer – blood flows consequently between the layers of the aortic wall.

Aortic dissection occurs when the innermost layer of the aorta (intima) tears and blood flows between the layers of the aorta’s wall. Due to the dissection blood flows in two channels – a true lumen and a false lumen – blood supply to the various organs variably arises from these two channels and affects/ compromises organ function and survival.

Loss of the combined integrity of the three layers leads to the aorta immediately thinning out because of the dissection – with potential for rupture as an immediate complication or aneurysm formation and risk of rupture at a later date.

Aortic dissection tens to occur for many reasons:

Uncontrolled high blood pressure, genetics, due to trauma sustained in a motor vehicle accident or fall from a height, high cholesterols, old age with atherosclerosis, illicit drug use and in chronic smokers among other causes.

Certain genetic syndromes predispose to aortic dissection either due to a weak aortic wall or due to gradual enlargement of the aorta (aneurysm). Besides some patients are born with – a Bicuspid Aortic Valve (a condition where the aortic valve has 2 leaflets in lieu of the normal 3) – these patients are more prone to having an aneurysms of the ascending aorta and the aortic root – predisposing them to aortic dissections.

The dissection may involve any part of the aorta starting from just above the aortic valve to all the way down to the abdomen where the aorta divides into the blood vessels supplying the lower limbs.

The most common symptom experienced by patients who have an aortic dissection is severe, tearing pain in the chest or upper back.

Since the aorta is the major artery from where other vessels arise from some patients may have chest pain like heart attack – when the coronary arteries supplying the heart are affected. If the blood vessels supplying the brain are involved symptoms may be like that of a stoke viz. loss of consciousness, blackout, loss of power in the arms or legs or slurred speech. Some experience symptoms due to what is describes as ‘malperfusion’ – wherein blood to certain organs like the intestines – causing nausea and vomiting, kidneys (abnormalities on laboratory tests) and the arms and legs are affected (loss of power in the arms and legs and other symptoms like tingling and numbness).

Some patients have blood supply to the spinal cord affected leading to acute paraplegia (loss of power in the limbs) or in some cases shortness of breath when the aortic valve is involved in the aortic dissection.

  • The decision to proceed with testing is made based on the clinical history and the physical findings on clinical exam.
  • An urgent CT scan of the entire aorta is performed to arrive at a diagnosis and proceed with treatment planning.
  • This is usually followed by an Echo and laboratory investigations.

The treatment of an aortic dissection depends on the part of the aorta involved.

Those involving the aortic root, ascending aorta are life-threatening, and time is of the essence to save one’s life due to the risk of complications like –rupture and bleeding, involvement of the coronary arteries and the aortic valve.

Surgery usually involves replacing the involved portion of the aorta with a tube graft and repair/ replacement of the aortic valve or re-implantation of the neck vessels in various combinations or in isolation depending on the pre-operative CT scan and intra-operative findings.

The dissection involving the aorta beyond the arch – descending thoracic aorta (where the vessels to the brain and upper limbs come from) are usually managed medically with intervention in certain situations.

Therapy would include strict blood pressure control, imaging and regular follow up to detect possible complications early.

Certain patients with descending thoracic aortic dissections may undergo Thoracic Endovascular Aortic Repair (TEVAR) wherein a stent graft made of fabric and supported by a wire framework is inserted into the true lumen od the dissection in order to seal the intimal tear.

This may be performed in emergent situations where malperfusion to the organs in the abdomen or the circulation to the lower limbs may be compromised among other indications.

Aortic aneurysm surgery is considered major surgery and it would be best to discuss the risks and the conduct of the operation in detail with the surgical team well in advance.

The post-operative course is largely guided by the pre-operative status and co-morbidities of the patient prior to surgery.

Even with surgery follow up is essential to diagnose complications and manage them early.

CT scans on follow up are essential at pre-determined intervals.

This follow up would include regular follow ups with the surgeon and cardiologist for strict control of blood pressure. Activities with severe physical exertion are to be avoided; smoking cessation is mandatory.

Aortic Aneurysms

Aortic Aneurysm and Aortic Surgery

The aorta is the main blood vessel that carries blood out of the heart to the rest of the body.. It starts from the aortic valve and goes all the way down to the abdomen where it divides into the blood vessels supplying the legs.

An aneurysm is a bulge that occurs in the vessel wall due to the wakening of the vessel wall. These can occur in any part of the aorta but are more common in the abdomen and the other common area is in the chest.

Most aortic aneurysms are detected when a patient is evaluated for other symptoms or as a workup for other disease processes – incidental detection. While some present with symptoms of a pulsating swellingin the abdomen or from symptoms due to compression of surrounding organs in the chest (breathlessness or difficulty in swallowing) or abdomen. The most catastrophic is when they present as an emergency either due to tear in the blood vessel wall (dissection) or when they rupture.

The causes are varied and can be either one or a combination of many. They are found more commonly in those with

  • Uncontrolled high blood pressure
  • Elderly people
  • Chronic smokers
  • Following injury to the aorta – sustained in motor vehicle accidents/ falls
  • Those with elevated cholesterols with widespread atherosclerosis
  • Infection and inflammation of the aorta
  • Congenital causes – Marfan or Ehlers-Danlos syndrome

Aneurysms of the aorta progress in size slowly and symptoms may be insidious in onset. They usually result from the compression of neighbouring structures in the chest and abdomen.

  • Difficulty in swallowing
  • A change in the voice/ hoarse voice
  • A pain in the back or upper abdomen
  • Palpitations

As mentioned, aortic aneurysms develop and increase in size slowly. Hence most patients are asymptomatic and may even have a normal physical examination.

These aneurysm are often detected other tests are performed like a Chest X-ray, a CT scan or an MRI for other conditions or on high suspicion of compression by a mass causing symptoms like hoarseness, difficulty in swallowing.

The aorta is an elastic vessel with three layers – made to sustain the pressures at which blood is pumped through it.

There are standard sizes for aortic dimensions.

Most aneurysms are small and are managed with control of blood pressure and advise on lifestyle modification. When the vessel size increases beyond a diameter the pressure in the vessel goes up exponentially in relation to its radius. When your blood pressure is too high, it puts more stress on the wall of the aorta where the aneurysm is located. At a diameter and with the thinning of the aorta due to the aneurysm – there is a high probability of the two most dreaded complications – dissection and rupture!

This is very significant when the aneurysm reaches 5.5-6 cm and it is advised to undergo intervention when it reaches these dimensions. Another factor that impacts early intervention is rapid growth of the aneurysm with time (0.5 to 1 cm per year).

Occasionally the ascending aorta (the part of the aorta above the aortic valve) may be found to be larger than normal. In such situations a decision may be taken to replace the aorta at the time of other surgery viz. aortic valve replacement, coronary artery bypass surgery (CABG) as the aorta tends to become bigger with time and age. This would need a second surgery later in life.

Having these factors in mind treatment of patients suffering from aortic aneurysms is individualised.

The initial evaluation after the diagnosis of an aortic aneurysm is a CT scan of the aorta.

The immediate diagnosis of an aortic aneurysm doesn’t mandate surgery.

The surgical team would need to look at the dimensions of the aorta, the co-existing pathology and arrive at a decision regarding further course of action.

In some cases, follow up is mandated at regular intervals to keep a track of the aortic aneurysm size so that intervention can be planned at the right time.

In the meantime, the patient would be optimized with medical management to modify risk factors and hence retard the rate of growth of the aneurysm – adequate blood pressure control, smoking cessation, avoiding strenuous physical activity and lipid control.

The options would either be surgery or endovascular intervention depending on the location and other features of the aneurysm

If your aneurysm is large enough, or if the aneurysm is growing quicker than usual, surgery may be recommended.

Aneurysms involving the ascending aorta (the part of the aorta just above the aortic valve) are managed by replacing the diseased aorta with a specialised tube graft.

Disease of the aortic valve and its immediate surrounding structures may need a more complex procedure aortic root repair/ replacement.

More complex are those aneurysms that involve the aortic arch (where the blood vessels to the upper limbs and brain come off.

Most surgeries are performed through an incision in the front of the chest – a few select patients may be suitable for a minimally invasive procedure.

Aneurysms in the chest cavity (close to the left lung) – Descending Thoracic Aneurysms are managed by operating through the left chest.

A good proportion o Descending thoracic aneurysms can be managed by a procedure called Thoracic EndoVascular Aortic Repair (TEVAR).

Again these procedures are best performed in centres with adequate expertise in management of these complex cases.

Aortic aneurysm surgery is considered major surgery and it would be best to discuss the risks and the conduct of the operation in detail with the surgical team well in advance.

The post-operative course is largely guided by the pre-operative status and co-morbiditiesof the patient prior to surgery.