Heart Defect ASD
An Atrial Septal Defect (ASD) is a common congenital cardiac defect that consists of a hole in the septum between the two filling chambers of the heart, the atriums. As the blood pressure in the left side of the heart is much higher than the blood pressure in the right side of the heart, blood flows continuously to the right side between this hole. Therefore the right heart side enlarges and has to do much more work than usual.
Many children diagnosed with an ASD do not have any symptoms and appear to be in good condition. If you have a large ASD however, the right side of the heart will be distended, the right ventricle will have to do additional work and the lungs will be overstrained and finally the following symptoms can occur:
- Heart murmur
- Heart palpitations or skipped beats
- Shortness of breath, especially when exercising
- Rapid breathing
- Frequent lung infections
- Poor growth
- Impaired exercise capacity
Even if you do not have any symptoms, it is important to close the defect. If not corrected, there is a high risk the right ventricle will fail over time. ASD symptoms may not occur until adolescence or adulthood. An adult who has had an undetected ASD for decades will suffer from heart failure symptoms earlier in life such as arrhythmias, shortness of breath, water accumulation in the legs (edema) and impaired exercise capacity. These people will have a shortened lifespan from heart failure or high blood pressure in the lungs. To prevent these types of complications an ASD closure should be carried out when the defect is diagnosed.
Closure of ASD and PFO
Once the diagnosis of an ASD suitable for interventional closure, or a PFO responsible for paradoxical embolism is made, it is time to close it. Today, in most cases of patients with an ASD and in nearly all patients with a PFO, closure can be achieved without open-heart surgery but by using interventional catheterization.
Interventional closure: The closure is performed in a cardiac catheterization laboratory, a so-called cath lab. Techniques vary between clinics and physicians active in catheter intervention. The procedure can be done under local anesthesia, with the support of sleeping medication (sedation) or by general anesthesia and will be performed by a (pediatric) cardiologist. A thin tube – a catheter – is inserted into a blood vessel in the groin and guided to the heart. The exact size of the PFO or ASD is measured by ultrasound transesophageal echography(TEE), intracardiac echography(ICE) and the surrounding tissue is assessed. In many cases of PFO and in most patients with an ASD, the size of the defect is measured exactly by inserting a soft balloon, known as balloon sizing. Everything is constantly controlled by X-ray. Then the catheter is exchanged for a larger catheter, the delivery sheath.
The appropriate device, an ASD occluder or a PFO occluder is pushed through to be placed across the hole, through the delivery sheath. The occluders consist of a left-sided disk and a right-sided disk. The left-sided disk is deployed first and then retracted directly to the septum. Then the right-sided disk is deployed and thus the occluder will seal the defect between the two disks. Once the device is in the correct position, the physician will release the device and withdraw the delivery sheath. The defect is now closed and the tissue will grow around the device and be a permanent part of the septum. Typically the procedure takes approximately 60 minutes.
Occluder and MRI
This device contains no magnetic parts. An MRI or any other conventional X-ray can be carried out immediately after the procedure.
Occluder and airport
Illustrations of ASD
ASD area shown on a normal, healthy heart
A heart with a ASD defect
An atrial septal defect (ASD) is a hole in the septum between the right and left atrium. As the blood pressure on the left side is higher than the blood pressure on the right side, this leads to a continuous blood flow across the ASD from the left to right side and consequently to an enlargement of the right side of the heart.
Closing the defect
The closure is performed in a cardiac catheterization laboratory, a cath lab. A thin tube – a catheter – is inserted into a blood vessel in the groin and guided to the heart. The size of the ASD is measured by ultrasound (TEE,ICE) or with a balloon catheter. The catheter is then exchanged for a larger catheter, the delivery sheath. The appropriate device, an ASD occluder, is pushed through to be placed across the hole through the delivery sheath. Once the device is in the correct position and firmly attached on both sides, the physician will release the device and withdraw the delivery sheath.
Occlutech ASD device in position
The Occlutech device used to close an ASD defect is called the Occlutech Figulla Flex II ASD. The device is made of braided Nitinol threads. Nitinol is a very elastic metal with wide-ranging memory properties. The device consists of two discs with a larger intermediate waist. Inside each of the discs there is a Polyethylene (PET) patch, to support the immediate closure. This helps stop the blood going through the meshwork of the device. Occlutech’s unique patented braiding technology allows the device to be manufactured without a left sided hub, minimizing both the risk of thrombus formation and damaging the distal wall of the left atrium during implantation. The device will be pushed through the delivery catheter across the defect, then both discs will fix the device at the septum wall and the device will then be released when placed in the correct position to close the defect.