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Atrial Septal Defect (ASD) Closure

ASD 1Overview

The heart is divided into four separate chambers. The upper chambers, or atria, are divided by a wall called the atrial septum.

Septal defect is a hole in the septum. A defect between the heart's two upper chambers (the atria) is called an atrial septal defect (ASD). Atrial septal defects are one of the most common heart defects, and are caused by incomplete growth of the septal wall during fetal development.

There are several types of atrial septal defects - they are classified by where they occur and their size. A secundum ASD is a hole in the middle of the atrial septum, which lets blood flow from the left chamber to the right chamber, or from the right chamber to the left chamber, depending on pressures in the atria.

When an atrial septal defect is present, blood flows through the hole, usually from the left atrium to the right atrium. This increases the blood volume in the right atrium, which causes more blood to be pumped to the lungs. Because it is receiving so much extra blood, the right side does more than the normal share of work. This may cause you to feel tired, have difficulty in breathing or be sick more often with respiratory infections such as cold or pneumonia. 
 

How do I know if I have an Atrial Septal Defect (ASD)?

Causes of ASDs
Congenital heart problems are caused by specific genetic defects, meaning it is a defect that exists at the time of birth. In other words, the defect is an abnormality, not a disease. The septum between the two atria of the heart did not develop normally before birth. What is known is that about 20 percent of ASDs that occur in infants close on their own in the first years of life.

Most congenital heart defects are likely due to maternal environmental factors combined with genetic predisposition and other medical conditions (Down’s syndrome, for example). These environmental factors include alcohol and street drugs, as well as diseases such as diabetes, lupus and rubella.  Sometimes a viral infection can cause heart defects to develop.

Diagnosis
Atrial Septal Defects (ASD) assessment and diagnosis may be done using:
  • ECG – an electrocardiogram, a graph of the heart’s electrical activity (heartbeat).
  • Chest x-ray – to evaluate the size of the heart and lungs.
  • Transthoracic echocardiography – an ultrasound image of the heart combined with measurements of blood flow to assess the heart’s structure and function.
  • Transesophageal echocardiography (TEE) – an ultrasound image obtained via the esophagus to provide a clearer image of the atria, more precisely define the defect’s size and shape and to evaluate the health of the heart valves. Using TEE, the physician can easily distinguish a PFO from other types of ASD.
  • Right heart catheterisation – a procedure during which a small thin tube (catheter) is inserted into the heart via the peripheral vein. Pressures are measured in each chamber as well as the oxygen saturations (how much oxygen is present in the blood). The latter measurements determine how much blood is flowing across the defect by measuring how much the oxygen level increases beyond the site of the defect.
 
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Why do I need an ASD closure procedure?

ASD 2Under normal circumstances, the right side of the heart pumps blood low in oxygen saturation to the lungs, and left side pumps blood that is high in oxygen saturation to the body. When ASDs occur, oxygenated and deoxygenated blood gets mixed together, reducing efficiency of the hearts function.

The risks associated with ASDs is greater when the size of the defect is large (greater than 2cm). These risks include:
  • Right heart enlargement (right heart failure);
  • Heart rhythm disturbances including atrial fibrillation or atrial flutter;
  • Stroke;
  • Pulmonary hypertension (high blood pressure in the arteries that supply the lungs). If pulmonary hypertension is severe, flow across the ASD (normally left to right) can reverse (become right to left). As a result, oxygen levels in the blood will decrease, leading to a condition known as Eisenmenger syndrome.
  • Leaking tricuspid and mitral valves as a result of the enlargement of the heart.
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How is an ASD treated?

Upon confirmation of an ASD, the treatment depends on the type and size of the defect, its effect on the heart, and whether any other related conditions such as pulmonary hypertension, valve disease or coronary artery disease are present. Your cardiologists is the best person to determine what type of repair is warranted.

ASDs can be treated non-surgically (preferred method of treatment for most ASDs) however surgery might be needed to repair some types of ASDs such as large atrial septal defects. Surgical repair is usually performed using a tissue patch, preferably from the patient’s own pericardium (heart tissue). Some ASDs can be surgically closed with sutures alone. Prior to the introduction of a non-surgical approach, ASDs were only treated surgically, regardless of the type of defect.

At Mercy Angiography we offer a non-surgical approach using the AMPLATZER® Septal Occluder to treat the septal defect.
 
ASD deviceThe AMPLATZER® Septal Occluder is made made from an alloy of nickel and titanium. Each occluder has a Nitinol wire mesh that is shaped into two flat discs and a middle, or "waist" to fit the defect size. The polyester fabric inserts are designed to help close the hole and provide a foundation for growth of tissue over the occluder after placement.

The procedure will be conducted in an angiography suite (“cath lab”) at Mercy Angiography, which is in the Mercy Hospital at 98 Mountain Road, Epsom in Auckland. Your interventional cardiologist will be assisted by nurses and other highly trained staff. As the ASD closure is performed using general anaesthesia, you will not be aware of anything during the procedure.
 
At the start of the procedure, your interventional cardiologist inserts a catheter (soft plastic tube) from a small incision in the groin, into the heart using fluoroscopy (x-ray) guidance. This process, known as cardiac catheterisation, is used to determine the size and location of the septal defect as well as measure pressures inside the heart chambers.

Following this, the closure device, attached to a catheter, is advanced to the heart and through the defect using x-ray guidance and echocardiography. The cardiologists then deploys the occluder to expand each disc on either side of the defect, closing off the hole.

An interventional cardiologist delivers the septal occluder into the heart via a small plastic tube called a catheter. , by an interventional cardiologist to access the heart and place the occluder using x-ray and echocardiography. The interventional cardiologists then deploys the occluder to expand each disc on either side of the defect, closing off the hole. Over time, tissue will grow over the implant and it will become part of the heart.
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How should I prepare for the procedure?

  • Fasting: You must not have anything to eat or drink six to eight hours before you procedure, unless the Anaesthetist tells you otherwise. You may continue to drink a small amount of clear fluids to take medications.
  • Medication: Please inform your cardiologist about all the medication you are taking. You cardiologist may advise you to stop taking some medication temporarily for a few days prior to your procedure e.g. blood thinners.
  • Allergies or previous reactions to contrast (x-ray dye): Please inform Mercy Angiography staff at the time of booking your procedure if you have any known history of allergies, particularly allergies to x-ray contrast and seafood.
  • Diabetes: If you are a diabetic you should inform your cardiologist and Mercy Angiography staff at the time of booking your procedure. You may need to discuss your insulin dose with your cardiologist.
Please bring with you any medication and any recent blood test results, ultrasound results or x-rays.

On the day of your procedure, please make your way to the Mercy Hospital Reception where they will be expecting you. You will be admitted to a hospital ward and transferred to Mercy Angiography for your procedure.

For directions to the Mercy Hospital, click here.
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What happens after my procedure?

  • After recovery from anesthesia and with adequate bed rest you should be able to sit up and move around.
  • You will stay in the hospital overnight and if there are no complications, you will be allowed to go home the next day. 
  • Because the procedure is less invasive than open-heart surgery, your recovery should be easier and quicker.
  • You may have an adhesive bandage where the catheter was inserted. You also may have a minor sore throat if an imaging probe (Transesophageal echo probe) was used.
  • Before you leave the hospital, your cardiologists will give you guidelines for activities and medications. They will also tell you when you can resume normal daily activities.
  • Medications will be an important part of your treatment and your doctor will prescribe drugs that you should take at home. The drugs should prevent blood clots from forming.
  • Notify your doctor if your medications cause unpleasant reactions, but do not stop taking them unless instructed to do so.
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