Overview of Catheter Management of Atrial Septal Defect
Atrial Septal Defect (ASD), a type of birth defect that affects the heart, is quite common. Roughly 6 to 10 out of every 10,000 babies born live have this condition. There are four types of ASD: primum, secundum, sinus venosus, and coronary sinus defects.
The symptoms of ASD can differ from individual to individual, and sometimes, there might not be any noticeable symptoms. If the defect is large, symptoms can appear early in a person’s life. Conversely, smaller defects might not cause symptoms until later. The signs of ASD include lack of growth, difficulty breathing, heartbeat that feels like it’s fluttering, swelling in the legs, feet, or abdomen, bluish-colored skin, and episodes of increased shortness of breath and feeling lightheaded when standing up (orthodeoxia-platypnea).
If someone has the secundum type of ASD, it’s possible to close the defect using a non-surgical method called a transcatheter closure. In the United States, there are two devices approved by the FDA to close ASD. Check out the image of how an ASD closure looks below.
Anatomy and Physiology of Catheter Management of Atrial Septal Defect
The heart is made up of four chambers: two upper chambers called atria and two lower chambers called ventricles. A wall called the inter-atrial septum divides the right and left atria, while another wall, the inter-ventricular septum, separates the right and left ventricles. These walls develop from two structures when the heart is forming in an embryo – the septum primum and the septum secundum.
Atrial Septal Defects (ASDs) are a group of defects that can occur in the hearts of some people. These defects are categorized based on where they are located in the heart. The most common type, secundum, is positioned at a spot called the ostium secundum. The second type, primum, involves a location called the ostium primum and is often associated with issues in the heart valves. The sinus venosus defects occur at the junction of the large veins (superior or inferior vena cava) and the right atrium. Lastly, the coronary sinus defect is when the roof of the coronary sinus is lost, causing a connection between the left atrium and the coronary sinus.
ASDs can also be classified based on size. Trivial cases are less than 3 mm in diameter. Small cases range from 3 to less than 6 mm, moderate cases are 6 to 8 mm, and large defects are greater than 8 mm in diameter.
Why do People Need Catheter Management of Atrial Septal Defect
When a person has an atrial septal defect (ASD), which is a hole between the two upper chambers of the heart, it might need to be closed to prevent serious health problems. The closure can be done through catheterization, which is when a small tube (catheter) is threaded through blood vessels to reach the heart. However, this only works for one specific type of ASD, called a secundum ASD. For other types of ASD, like the ones that are situated near the valves that control blood flow in and out of the heart (primum type) or those that affect how the veins connecting to the lungs work (sinus venosus type), open surgery is needed.
A catheter approach might be used if the person has:
* An ASD that’s causing symptoms bad enough to affect the person’s everyday life
* An ASD that’s causing the right side of the heart to get bigger, even if the person doesn’t have any symptoms
* An ASD that’s causing more blood to flow to the lungs than to the rest of the body, even if the person doesn’t have any symptoms
* A clot or other unwanted material that got into the bloodstream through the ASD, then got stuck somewhere else in the body, causing damage or symptoms. This is referred to as a paradoxical embolism.
When a Person Should Avoid Catheter Management of Atrial Septal Defect
There are certain conditions where closing an Atrial Septal Defect (ASD), a hole in the wall between the heart’s upper chambers, with a non-surgical approach (transcatheter approach) is not advised. These may include:
ASD types other than the secundum type. This could be the primum type, the sinus venosus type, or defects in the coronary sinus.
Severe pulmonary hypertension – This is a condition where the blood pressure in the lungs is too high. If it’s severe enough to be higher than about two-thirds of the blood pressure or resistance in the other parts of the body, it may not be safe to close the ASD.
Eisenmenger syndrome or net right to left shunt – These are medical conditions that affect the way blood flows through the heart and lungs. As a result, it may not be possible to safely close the ASD.
Defects larger than 38 mm (about 1,5 inches) in diameter – If the hole in your heart is this large, your doctor may advise another approach.
Insufficient rim of tissue around the defect – If there isn’t enough tissue to close off the hole properly, this approach isn’t advisable.
Equipment used for Catheter Management of Atrial Septal Defect
The process of addressing a hole in the heart, or an atrial septal defect (ASD), requires several key elements, all of which are managed inside a specialized room called a cardiac catheterization laboratory.
Firstly, it calls for a special type of ultrasound test called a Transesophageal echocardiography (TEE) or intracardiac echocardiogram (ICE). This test allows the doctor to visualize the inside of the heart and guide their work.
Then, an ASD closure device is required. This is a device specifically designed to plug the hole in the heart.
The ASD closure device is inserted via a catheter delivery system, which is a thin, flexible tube that can be navigated through blood vessels to reach the heart.
To ensure everything is happening as it should, a technique called fluoroscopy is used. This is like an X-ray movie that allows the doctor to see real-time moving images of your heart and the catheter.
Of course, all of this is performed under anesthesia to ensure you don’t feel pain or discomfort during the procedure. To avoid infections, antibiotics are also administered.
Who is needed to perform Catheter Management of Atrial Septal Defect?
A specially trained heart doctor, or interventional cardiologist, will be the one to guide your heart procedure. These doctors have particular expertise in dealing with problems of the heart’s structure. With them in the room will be a nurse who specializes in the cardiac catheterization lab, a supportive assistant, and a technician who is also skilled in working in the heart cath lab.
Altogether, this professional healthcare team will take care of you during your heart procedure. The heart doctor is in charge and uses specialized equipment to look inside your heart and arteries, diagnose what’s wrong, and fix problems they find. The nurse, assistant, and technician all have important tasks that help the procedure go smoothly. They help ensure that you are safe and comfortable throughout your procedure.
Preparing for Catheter Management of Atrial Septal Defect
Before undergoing a procedure for an atrial septal defect (ASD, a hole in the heart), patients need to be thoroughly examined. This includes asking about their medical history, especially any known allergies – for instance, to materials such as nickel. An ultrasound test of the heart that is done through the esophagus (a tube running from the mouth to the stomach) known as a transesophageal echocardiogram, is also carried out to look at the ASD and to determine if it can be repaired. The size of the ASD is measured so the correct size device can be chosen for the procedure.
In addition, a procedure called right heart catheterization is usually performed. This test helps check the pressure in the lung’s blood vessels and how much blood is passing through the ASD. If the ultrasound test doesn’t provide enough information about the ASD or any abnormal connections of the lung’s blood vessels, an MRI or CT scan of the heart can also be done.
Once it’s determined that a patient is a good match for repair of an ASD, the doctor will explain the potential risks and benefits of the procedure. The patient will then give consent if they agree to undergo the surgery. Finally, on the day of the procedure, doctors will make sure the patient does not have any active infections and is healthy enough for anesthesia.
How is Catheter Management of Atrial Septal Defect performed
The procedure of closing an ASD (a hole in the wall between the two upper chambers of your heart) through a method called ‘transcatheter closure’ is typically performed with the patient under mild sedation or under general anesthesia. This depends on how complex the hole in the heart is and whether TEE imaging (a type of ultrasound imaging to get more detailed pictures of your heart) is necessary. For most people with ASD, mild sedation is sufficient.
Before the procedure starts, an antibiotic is given to the patient to prevent any infections. Once the patient is sedated, the doctor then gains access to the patient’s blood vessels through a vein in the leg. Some doctors prefer to use the patient’s right femoral vein in the leg, or some doctors might opt to use both veins in both legs. This all depends on the doctor’s preference.
Next, a specialized catheter (a thin tube) with an ICE (intracardiac echo) imaging device is guided under X-ray control into the right side of the heart to check the size of the hole. Based on the measurements, a suitable closure device is chosen for the procedure. The device is then carefully positioned across the hole in the heart under the guidance of both X-ray and ICE imaging.
Once the doctor has ensured that the device is well positioned and the heart’s hole is sealed, the catheter and sheaths (thin tubes used to deliver the device into the heart) are carefully withdrawn. The doctor then double-checks the stability of the device and confirms the complete closure of the hole using color doppler imaging, a type of ultrasound that allows to see and measure the blood flow.
If no leaks are detected around the device, the device is left permanently in the heart and the sheaths and catheters are withdrawn from the body through the vein in the leg. Protamine, a medication that helps to limit the effect of the anticoagulant (a medication that prevents the blood from clotting) used during the procedure, may be given depending on the doctor’s choice.
Post-procedure, the patient is prescribed to take clopidogrel (a medication to prevent blood clots) and aspirin for six months. The patient is then monitored overnight, followed by a check-up echocardiogram (ultrasound of the heart) the next day to review the position of the device in the heart and to ensure that there are no complications.
If everything feels and looks fine, the patient is discharged and scheduled for a follow-up check-up in six months. The patient is also advised to have preventative medication for infections prior to undergoing dental procedure for six months post-operation.
Possible Complications of Catheter Management of Atrial Septal Defect
Closing the hole in the heart known as atrial septal defect (ASD) with a procedure called transcatheter ASD closure can sometimes lead to serious complications. These include:
* Device embolization: This happens when the device used to close the hole moves from its original location.
* Erosion of the cardiac structures from the device: This is where the device causes wearing away in the parts of the heart.
* Atrial arrhythmias: These are abnormal heart rhythms originating from the upper chambers of the heart, known as the atria.
* Atrioventricular block (AV block): A condition where the electrical signals between the upper and lower chambers of the heart are blocked.
* Persistent atrial aneurysm: This is when a an abnormal, weak area in the wall of the upper chambers of the heart continues to exist.
* Thromboembolism: This is a condition where a blood clot forms and then breaks off, travelling through the bloodstream and potentially causing blockages.
* Pericardial effusion and tamponade: This is when excess fluid accumulates around the heart, sometimes leading to a dangerous condition where the fluid compresses the heart (tamponade).
What Else Should I Know About Catheter Management of Atrial Septal Defect?
Medical experts suggest two main treatment options for secundum ASD (a hole in the wall between the two upper chambers of the heart): surgery or a procedure called transcatheter closure. Transcatheter closure is a method where a device is inserted into a blood vessel and guided to the heart to close the hole. Although both options are recommended, transcatheter closure has been considered a safer and more effective procedure for correcting the defect in the heart in suitable patients. It also has a low risk of complications. As a result, transcatheter closure has become the preferred treatment for closing secundum ASD defects.