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Aortic Coarctation
INTRODUCTION
The aorta is the largest and most important artery in the body. It carries blood pumped by the heart to the organs, muscles, and bones. Coarctation of the Aorta (CoA) is a narrowing of the aorta which usually occurs just after the arteries that supply the head, neck and upper limbs have branched off.
The major consequence of having a coarctation of the aorta is hypertension (high blood pressure) that exposes the heart and brain to extra stress starting at birth. Untreated significant coarctation of the aorta predisposes to stroke, heart attack, and “heart failure” in extreme cases.
Coarctation is really a spectrum of disease, ranging from mild to very severe, in extreme cases the aorta can be occluded (completely blocked). In most cases, the first line treatment of coarctation is to relieve the obstruction with surgery or with the use of a balloon and a large stent. In about 20 percent of patients there is also an associated narrowing of the aortic arch; we call this arch hypoplasia. Arch hypoplasia is a more difficult condition to treat and may require surgery as opposed to an interventional procedure. In other cases, imaging studies may suggest an irregularity of the aorta, but it may have no obstruction (blockage), this is called pseudocoarctation.
Right: Normal Aorta Left: Coarctation (narrowing)
Source: Cleveland Clinic
It is certainly possible to have re-coarctation. Sometimes when someone has had surgery to repair a coarctation as a child, or a stent has been used, a re-coarctation can occur. This means, the aorta can re-narrow at one of the suture lines as the patient grows or the size of a previously placed stent has to be enlarged with a balloon to accommodate growth. No matter the cause, re coarctation can usually be managed with balloons and stents and does not require another open procedure.
What does this mean for me?
Picture a garden hose lying flat on the ground with water flowing out of it. If you were to step on it, the section of the hose before your foot would develop a very high pressure, and the section of the hose after your foot would be very low pressure. Just like this, in CoA, there is high pressure before the narrowing, and very low pressure afterward. The narrowing usually separates the parts of the aorta delivering blood to the upper and lower parts of the body. As such, important parts of your upper body, such as the heart and brain, are continuously facing high blood pressure, while the lower extremities have low blood pressure.
Over time, this increases the risk for strokes, heart attacks, congestive heart failure, and aneurysms. An important thing to consider is that the high blood pressure from coarctation starts at birth which is why we feel it is important to treat it as early in life as possible.
The reason CoA can go unnoticed is that symptoms such as headaches, blood pressure elevation, mild breathlessness, and aching in the legs during exercise are common, non-unique symptoms.
Children
High blood pressure in a child associated with weak leg pulses is usually the tip off that there is a problem, but unfortunately coarctation is often missed until adulthood. For anyone diagnosed with high blood pressure we recommend taking the blood pressure in both arms and legs; a lower blood pressure in the the legs can be a sign of significant coarctation.
Pregnant Patients
Significant coarctation is usually dealt with before pregnancy. CoA may be associated with miscarriages. In mild cases no treatment may be required. Usually whether your coarctation has been treated or not, we recommend seeing a specialist in congenital heart disease and pregnancy.
Symptoms: How would I know if I have CoA?
Causes: Why do I have CoA?
Most patients with CoA don’t display specific symptoms. The classic symptoms are headaches and claudication (aching in the lower legs with walking or running). High blood pressure in the right arm is a classic sign. There may be a blood pressure difference between the arms. The blood pressure is usually 20 mm/hg in the left arm than right arms depending on the type and severity of the coarctation. Your doctor can make a diagnosis of coarctation by comparing the blood pressure in the arms and the blood pressure in the legs. If the systolic blood pressure (e.g. if the blood pressure is 120/70, 120 is the systolic blood pressure and 70 is the diastolic blood pressure) in the legs is 20 mmhg less than the right arm pressure, coarctation is implied as a possibility (there can be other explanations but this is usually the first piece of the puzzle that prompts further investigation). In severe cases, symptoms such as headaches, shortness of breath, claudication (muscles aching in calves, thighs, etc, while walking) and heart failure may also appear.
Next Steps: Investigation Plan
Mild cases of CoA may fly under the radar, as symptoms overlap with many other illnesses. As such, patients may only be diagnosed with CoA when they are under investigation for a different condition,it may also reveal this defect. For example, if a CT scan or MRI is conducted as a result of another condition. We have seen patients followed in a hypertension clinic for 20 years where the diagnosis has been missed. Usually in a young patient who has severe hypertension, a few tests will be conducted to determine the underlying cause.
The initial tests in a patient with coarctation usually include:
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An echocardiogram: an echocardiogram is an ultrasound of the heart. The echocardiogram is very helpful in identifying whether or not there is a bicuspid aortic valve and its functionality, whether the heart muscle is thickened, as well as the status of the ascending aorta (first part of the aorta). Although the echo may suggest there is a coarctation, it is not the best test for this problem and can be deceiving.
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MRI (magnetic resonance imaging): MRI is a test that uses strong magnets to create images. MRI is a great imaging test for young people because it provides outstanding images of the aorta with no radiation at all. By adding a special contrast agent called Gadolinium we enhance the quality of the study even more. MRI cannot be done in patients with certain medical implants (e.g. metal clips in brain, pacemakers etc). Also, the machine itself is built around a long tube that slides in and out of the machine where the images are acquired. Some people cannot deal with being inside the machine for the one hour or so it takes to get the images. Sometimes taking something to relax can help make it bearable, and make an MRI possible. Ask your doctor’s office about this.
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CT Scan (computed tomography): CT scan is a type of X ray which uses computers to reconstruct data. The scan these days are extremely fast and very high resolution. CT gives outstanding pictures of the aorta. The downside is that CT uses radiation to acquire the pictures. The dose is very low but still, we prefer to use CT only when that is the only way to get the information, especially in younger patients.
Treatment Options for CoA
Treatment options vary depending on the size, shape and location of the coarctation of your aorta. In addition, your medical history in terms of if you had prior surgery or a non-surgical procedure for the coarctation of your aorta can affect your treatment options.
Some treatments include:
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Have a nonsurgical, percutaneous (through the skin) procedure to put in a stent in your aorta to open up the narrow part. A stent is like a scaffolding; it is a very thin metallic tube that is used to hold open the aorta after the balloon it is mounted on, opens up the narrowing.
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Have an open chest surgery (usually by thoracotomy - incision on the left side between the ribs or sternotomy through the midline) to repair the narrow part of your aorta. Surgery is usually reserved for people with large aneurysms or with significant narrowing of the aortic arch (arch hypoplasia). Currently, instead of reparing the arch, surgeons will sew a large graft from the ascending to the descending aorta.
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Medications (for example, medication for high blood pressure)
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Continue to monitor your coarctation of your aorta, usually if it is mild and you do not have high blood pressure
Balloon Angioplasty and Stenting
Percutaneous (though-the-skin) balloon angioplasty and stenting is a non-surgical repair of coarctation of the aorta. It is the preferred and first line treatment for most coarctation of the aorta. Patients usually have the procedure, stay overnight, and are discharged home the next day. Like most things in medicine, some coarcations are clear cut and easily treatable with stents. For more complex coarctations, a multidisciplinary team will review all of the clinical data and imaging details. They will then come up with a treatment plan together.
Doctors are unsure of the causes of CoA. In some cases, it has been noted that genetic defects may be involved. For example, it has been noted that 80% people with CoA often have an aortic valve defect (bicuspid aortic valve) as well. The converse is not true.
CoA is a congneital heart defect, meaning people are born with it. However patients who are born with CoA may only become aware of it later in life.
Long Term Health Implications
Coarctation of the aorta is not a focal disease that can be fixed with a stent or surgery. The aorta itself is often abnormal; there is reduced elastic tissue and more fibrous tissue leading to increased aortic stiffness. This stiffness will persist after the narrowing has been dealt with through either surgery or a stent procedure. About 30 percent of patients who have coarctation that is repaired will continue to be on medication for high blood pressure.
The heart muscle is similar to other muscles in the body - the harder it is forced to work, the thicker it will become. The increased aortic stiffness and the narrowing of the aorta at the site of the coarctation means the the heart has to continuously work harder to push blood to the body. As a result there may be an enlargement of the aorta or walls of the heart. When we follow patients with coarctation we will usually perform an imaging study every few years for “surveillance”, to keep an eye on the aorta.
Untreated or inadequately controlled high blood pressure is a problem. Uncontrolled high blood pressure over time can lead to severe conditions such as stroke, coronary artery disease (a narrowing of the arteries that supply the heart with blood), heart attacks, brain aneurysms or brain hemorrhages. When we see patients with coarctation we focus on blood pressure control as part of the visit. Getting control of the blood pressure is helped by maintaining a healthy weight and diet, moderating alcohol, and sometimes will require medication for life.
The goal of treatment is to reduce the burden on brain and heart. With treatment the prognosis is usually very positive, and patients can be expected to have a very long and healthy life. Roughly 30% people will still have residual hypertension, but they may require less mediation.
Open Heart Surgery
Your coarctation may be relieved in an open chest surgery. Open chest surgery usually involves a left lateral thoracotomy (an incision between the ribs on the left side) or sternotomy (mid-line incision). Through this incision the surgeon can reach your aorta. Presently, the most common operation that is done involves removing the area of the coarctation and sewing the ends together (end to end repair). For more complex coarctations, an ascending aorta to descending aorta bypass may be used.
For example, surgery may be done on patients who have aneurysm of their coarctation site or for patients who have coarctations that are not amenable to stenting. If you have arch hypoplasia and require surgery, the surgical approach will vary depending on multiple factors.
At present, the Canadian, American, and European practice guidelines suggest coarctation stenting as the first line treatment in centres with expertise.
Primary Intervention:
The Transcatheter Approach
When undergoing this procedure, you will be awake and sedated with anesthesia, so that you have a reduced sense of pain, and remain comfortable. Usually we will insert a tube in the artery in your wrist and a tube in the artery in your leg. Using x-rays, a catheter (long, thin tube) will be advanced to the area of the narrowing from above and below. We will measure the pressure across the narrowing and take a few angiograms (pictures) using X ray dye. You will feel a warm feeling during the angiograms. We will then make some measurements. Based on the results, we will choose an appropriate balloon and stent. We will then advance a larger tube up from below to deliver the stent. The stent (small mesh tube) will serve to reinforce the aorta at the area of the narrowing to prevent it from recoiling. A few more angiograms will be taken to make sure that all is well and we are happy with the stent placement. After this, we will end the procedure and remove all the catheters. A suture will be placed in the leg incision to control bleeding.
After the procedure, you will be observed in holding area and spend one night in the hospital for observation. You will be discharged early the next morning.
The risks of the procedure include: heart attack, stroke, death, need for emergency surgery, major bleeding, requiring a blood transfusion, and the need for a surgical repair of the artery in the leg. There may be other risks that are specific to your situation that your doctor will discuss with you.
Frequently Asked Questions
Are there any lifestyle restrictions following coarctation stenting?
If you have a stent put in, take antibiotics in contaminated procedures for life. E.g. dental cleaning. Take baby Aspirin for first six months at a minimum.
Will I need any further treatments following treatment?
You will be called for a follow up visit in 2 months time with a CT scan to check your progress. After an year, a follow-up study will be done to verify that no fractures or obstructions are present across your stent. We will follow up with you yearly and conduct a focused CT scan every few years.
Can I play sports?
Fitness is encouraged but it is recommended that you avoid contact sports.
Will OHIP (public insurance) cover my procedure?
Yes.
How urgent is the treatment?
The urgency of treatment is highly dependent on your situation.
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Socorro (Sue) Jimeno
Clinical Coordinator, Structural Heart Disease Program
Phone: 416 340 4800, extension 6258
Fax: 416 340 4741
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Structural Heart Disease Program (Patients)
Socorro (Sue) Jimeno, Clinical Coordinator
Phone: 416-340-4800, extension 6258
Fax: 416-340-4741
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