Device Closure Of Atrial Septal Defect

Transcatheter Device Closure Of Atrial Septal Defect (ASD)

An alternative to surgical closure of atrial septal defect (ASD) is the use of specially made devices to close the ASD. These devices are implanted using special delivery system through a catheter during cardiac catheterization. This is considered a less invasive method than open heart surgery.

The advantages of transcatheter device closure are:

1. No need for cardiopulmonary bypass (use of the heart-lung machine) or cardioplegia (temporarily stopping the heart).


2. No large surgical scar on the chest. At the end of the procedure, there are only small needle puncture marks at the groin region; stitches are also not necessary.


3. Minimal pain compared to surgery.


4. Shorter hospital stay - the child can be discharged the day after the procedure.

Not all atrial septal defects are suitable for transcatheter device closure, and patients need to be carefully assessed prior to recommending this method of closure. Different devices are available for transcatheter closure of ASD. The commonest device used in our institution is the Amplatzer Septal Occluder (Figure 27.1) by AGA Medical Corporation.

Fig 27.1
The Amplatzer Septal Occluder

How The Amplatzer Septal Occluder Is Implanted

1. The whole procedure is carried out in the Angiography Suite while the child is under general anaesthesia.
   
2. The ASD is reassessed using transesophageal echocardiography. This will enable the cardiologist to visualize the ASD more clearly and to define its margins better.
   
3. Vascular access is via the femoral vessels (figure 27.2). Once the sheaths are in place, cardiac catheters can be used to assess the various chambers of the heart and to approach the ASD. Shunt calculation and angiography are performed.
   
   Fig 27.2
   Vascular access during cardiac catheterization. The inset shows sheath inserted at the groin. The black line shows the path of the catheter to the ASD.


4. The ASD is then sized before selecting the device of appropriate size. One way to accomplish this is to use the Amplatzer Sizing Balloon (figure 27.3). A catheter containing a balloon is introduced into the heart where the balloon is inflated to measure the stretched diameter of the ASD.
   
   Fig 27.3
   The Amplatzer® sizing balloons. Picture from AGA Medical Corp.


5. The Amplatzer Septal Occluder of the appropriate size is then screwed securely onto the delivering system and then carefully delivered across the ASD to close it (figure 27.4). Once positioning and stability are confirmed, the device is unscrewed to detach it, and the catheter removed.
   
   Fig 27.4
   Animation demonstrating how the Amplatzer Septal Occluder is delivered to close an atrial septal defect.


6. Chest X-ray, echocardiogram, electrocardiogram and urine dipstix test are performed the next day, after which the child can be discharged. The child is put on low dose oral aspirin for 6 months.