Co-arctation of the Aorta

Co-arctation of the Aorta (CoA) also known as Aortic Co-arctation
This page is dedicated to Louise

Definition

Aortic coarctation is a narrowing of part of the aorta (the main artery leading to the heart). It is a type of birth defect. Coarctation means narrowing.

The aorta is the main artery that sends oxygen-rich blood from the heart to the body except the lungs. Coarctation of the aorta is a constricted segment of the aorta that obstructs blood flow to the body. The left ventricle has to pump harder because the pressure is high. Because of this, the heart may enlarge. Coarctations most often occur as isolated defects, but may occur with a ventricular septal defect, subaortic stenosis, or complex congenital heart defects. Surgery may be needed to correct the defect, depending on the severity of the coarctation and the presence of other congenital defects. Another option may be a balloon angioplasty.

COA accounts for up to 8% of all congenital heart defects of all children with congenital heart disease and is more common in boys than girls..

What It Is

The aorta is the body's main artery. It distributes oxygen-rich blood to all parts of the body except the lungs. The first branches of the aorta go to the upper body (arms and head). After that, blood goes to the lower body (abdomen and legs). Coarctation of the aorta is a narrowing of the aorta between the upper-body artery branches and the branches to the lower body. This blockage can increase blood pressure in your arms and head, reduce pressure in your legs and seriously strain your heart. Aortic valve abnormalities often accompany coarctation.

Types

Preductal coarctation
The narrowing is proximal to the ductus arteriosus. If severe, blood flow to the aorta distal (to lower body) to the narrowing is dependent on a patent ductus arteriosus, and hence its closure can be life-threatening.

Ductal coarctation
The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus arteriosus closes.

Postductal coarctation
The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus blood flow to the lower body can be impaired. Newborns with this type of coarctation may be critically sick from the birth.

Causes, Incidence, and Risk Factor

The aorta carries blood from the heart to the vessels that supply the body with blood and nurtrients. If part of the aorta is narrowed, it is hard for blood to pass through the artery. People with this condition often have high blood pressure in the upper body and arms (or one arm) and low blood pressure in the lower body and legs.

Aortic coarctation is more common in persons with certain genetic disorders such as Turners syndrome. However it can also be due to birth defects of the aortic valve, such as bicuspid aortic valve.

Aortic coarctation occurs approximately 1 out of 10,000 people. It is usually diagnosed in children or adults under the age of 40.

Presentation

1. Neonatal presentation If severe, usually presents in first 3 weeks of life with poor feeding, lethargy, tachypnoea or overt congestive cardiac failure and shock. Initially the baby may be well but become ill after closure of the ductus arteriosus. Pulses may be reduced in amplitude and delayed between upper and lower limbs. BP higher in upper limbs compared to lower. Differential cyanosis can occur with flow across patent ductus from right to left side of circulation. The upper body appears pink and the legs cyanotic. A systolic murmur in the left infraclavicular area is typical but a range of murmurs may be heard depending on collateral circulation and other cardiac abnormalities.

2. Late presentation May be diagnosed incidentally due to presence of a murmur or hypertension. Can cause headache, nosebleeds and leg cramps, particularly with exercise, although claudication is unusual. Lower-limb muscle weakness, cold feet or neurological symptoms in the legs due to poor blood supply to spinal cord may be the presenting feature. BP may be higher in upper limbs, but left arm BP can be normal/low if coarctation involves the origin of the left subclavian artery. Simultaneous palpation of upper and lower limb pulses reveals radio-femoral delay with reduced pulse amplitude in lower limbs. Systolic or continuous murmur is usually heard in left infraclavicular area and under the left scapula. An ejection click may signify associated bicuspid aortic valve (present in ~85% of cases). A thrill or hum due to flow in aberrant collateral vessels may be present over the chest or abdominal wall.

Signs and Symptoms

Arterial hypertension in the right arm with normal to low blood pressure in the lower extremeties is classic. Poor peripheral pulses in the femoral arteries may be found in severe cases.

If the coarctation is situated before the left subclavian artery, asynchronous radial pulses will be detected in the right and left arms. A radial-femoral delay between the right arm and the femoral artery (groin) would be apparent, whilst no such delay would occur under left arm radial-femoral palpation.

A coarctation occurring under the left subclavian artery will produce synchronous radial pulses, but radial-femoral delay will be present under palpation in either arm.

Symptoms depend on how much blood can flow through the artery. In severe cases, symptoms are seen when the baby is very young. In milder cases, symptoms may not develop until the child has reached adolescence.

Symptoms include:

Dizziness or fainting
Shortness of breath
Pounding headache
Chest pain
Cold feet or legs
Nosebleed
Leg cramps with exercise
Hypertension (high blood pressure) with exercise
Decreased ability to exercise

NOTE: There may be NO symptoms

Tests

A health care worker will perform a physical exam and take your or the child’s blood pressure in the arms and legs. The pulse will be checked. The pulse in the femoral (groin) area is weaker than the carotid (neck) pulse. Sometimes the femoral pulse may not be felt at all.

The doctor will use a stethoscope to listen to the heart and check for murmurs. People with coarctation of the aorta have a harsh murmur that can be heard from the back.

Coarctation is often discovered during a newborn’s first examination or a well-baby exam. Taking the pulses in an infant is an important part of the examination since there may not be any other symptoms or findings until the child is older.

Tests to diagnose Coarctation of the Aorta may include:

Chest x-ray
ECG
Echocardiography
Doppler ultrasound of the aorta
Chest CT
MRI of the chest
Cardiac catheterisation and aortography

Both Doppler ultrasound and cardiac catheterisation can be used to see if there are any differences in blood pressure in different areas of the aorta.

With imaging, resorption of the lower part of the ribs may be seen, due to increased blood flow over the neurovascular bundle that runs there. Post-stenotic dilation of the aorta results in a classic ‘reverse 3 sign’ on x-ray. The characteristic bulging of the sign is caused by dilation of the aorta due to an indrawing of the aortic wall at the site of cervical rib obstruction, with consequent post stenotic dilation. This physiology results in the reversed ‘3’ image for which the sign is name.

Coarctation of the aorta can accurately be diagnosed with magnetic resonance angiography. In teenagers and adults echocardiogram may not be conclusive. In adults with untreated coarctation blood often reaches the lower body through collaterals, eg, internal thoracic arteries via the subclavian arteries. Those can be seen on MR or angiography. An untreated coarctation may also result in hypertrophy of the left ventricle.

Expectations

Coarctation of the aorta can be cured with surgery. Symptoms quickly get better after surgery. Most of the time, surgery to fix coarctation of the aorta is done during infancy.

Treatment and Surgery

Surgery is usually recommended. The narrowed part of the aorta will be removed. If the problem area was small, the two free ends of the aorta may be re-connected. This is called anastomosis. If a large part of the aorta was removed, a Dacron graft (a synthetic material) is used to fill the gap.

In some cases, balloon angioplasty may be done instead of surgery.
The narrowing can be removed by surgery or sometimes by non-surgical balloon dilation in the cardiac catheterization lab. Aortic coarctation may return even after successful surgery or balloon dilation. This isn't uncommon if your repair was done when you were a newborn. (It's uncommon if it was repaired when you were a child.) If you've reached your full adult size and have no blood pressure difference between your arms and legs, it's highly unlikely that your aorta will become obstructed again.
Recurrent coarctation is usually treated with nonsurgical balloon dilation or by implanting a stent using cardiac catheterization.

The need for surgery or catheterization depends mostly on the level of pressure in your arms and legs when you're resting and, under some circumstances, during exercise. If your arm and leg blood pressures are normal, you probably won't need more intervention.

Balloon Angioplasty:
A catheter with an inflatable balloon is introduced from an artery in the leg. The balloon is inflated to enlarge the narrow area.

Coarctation Repair:
Conventional repair involves the removal of the narrow segment with the ends being sewn together ("end to end").

Subclavian Flap:
With this type of repair the left arm artery (Subclavian Artery) is used to produce a flap to enlarge the Aorta and repair the Coarctation.

Ongoing Care

Medical
After the coarctation is repaired, you'll need your blood pressure checked every 1-2 years. The reason is that you're at higher risk of developing generalized high blood pressure or problems with your aortic valve. Both of these can be checked for during your routine cardiology visits.

Activity Restrictions
Depending on your blood pressure at rest or during exercise, you may be advised to avoid some forms of strenuous exercise. Heavy isometric exercise, such as power weightlifting, may be a particular concern if your pressure is elevated. In general, you don't need to restrict activity if your arm and leg blood pressures are normal. Ask your cardiologist if you should limit any activity.

Endocarditis Prevention
You may need antibiotics before certain dental or surgical procedures if you have an aortic obstruction or aortic valve abnormality. (See previous blog on Bacterial Endocarditis.)

Pregnancy
Most women with repaired coarctation shouldn't have any difficulties, unless there's residual aortic obstruction or generalized high blood pressure. However, if you have persistent coarctation or any associated problems that might affect you or your baby, check with your physician before considering getting pregnant.

Problems You May Have

Symptoms
Coarctation of the aorta usually doesn't have symptoms. However, if the obstruction becomes severe, you may not tolerate exercise well. You could have a headache or leg pains after exertion. You also might have chest pain or palpitations. Tell your cardiologist promptly about any activity-related symptoms.

Prevention
The condition may be suggested by prenatal ultrasound scanning but is difficult to detect. Vigilance in looking for the lesion in the children of affected parents may forewarn of potential neonatal problems.

The British Heart Foundation are doing booklets for Parents of children to help understand their childs heart and the booklets are also for health professionals.

Here is the link for Coarctation of the Aorta.
http://www.bhf.org.uk/publications/view_publication.aspx?ps=1000798

I pulled all the above information for this article from the various websites listed below:

http://www.congenitalheartdefects.com/typesofCHD.html#Coarc
http://www.patient.co.uk/showdoc/30000428
http://www.nlm.nih.gov/medlineplus/ency/article/000191.htm
http://www.heartpoint.com
http://www.en.wikipedia.org/wiki/Aortic_coarctation
http://www.rch.org.au/cardiology/defects.cfm?doc_id=5093
http://www.americanheart.org/presenter.jhtml?identifier=11069
http://www.rch.org.au/cardiology/defects.cfm?doc_id=5093

Disclaimer: The facts and opinions shown on this blog are as accurate and up to date as possible, but are provided as general "information resources", which may not be relevant to individual persons. This blog is not a substitute for individual assessment and always take advice from a doctor who is familiar with the particular person.

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Educating and Raising Awareness of Congenital Heart Defects