Introduction

Atrial septal defect (ASD) is a defect between the two upper heart chambers (the atria). This defect allows mixing of oxygenated and deoxygenated blood, eventually causing right heart enlargement and high pressure in the lungs (pulmonary hypertension).

Moderate to large size ASD causing right heart dilatation and raised pressure in the lungs should be closed and closure can be performed either percutaneously using devices (through the femoral vein) or through open heart surgery.

Small ASD with no chamber enlargement, raised lung pressure or other complications needs only to be followed up at the clinic.

Percutaneous Closure of ASD

This procedure is performed to close the ASD by inserting a device through the blood vessels in the groin (percutaneous transcatheter approach) which will occlude the ASD.

How is the procedure performed

This procedure is performed in the cardiac catheterisation lab. You will be given an anaesthetic which may be general (GA) or local (LA) depending on the technique used. In most cases, this procedure is performed under general anaesthetic (GA) which is given by a qualified anaesthetist. Once anaesthetised, an imaging probe (TEE) will be passed into your gullet (oesophagus) for accurate sizing of the ASD and to assist during deployment of the device. You will lie on an X-ray table and an X-ray camera will move over your chest during the procedure. A plastic catheter (a long tube) will be inserted via a vein in the groin and navigated until it reaches the heart.

Sometimes (depending on individual case), the catheter is positioned at different chambers of your heart to measure the pressure and oxygen content prior to device closure. In certain circumstances, balloon sizing of the ASD may be required. Once your doctor is satisfied with all the measurements, the appropriate size device is connected onto a cable, put into a special delivery tube, advanced through your ASD and carefully deployed. Your doctor will study the device’s position and stability before releasing the device. The catheter and imaging probe are removed and the procedure is completed.

Is the procedure safe

The procedure usually takes between 1 to 2 hours and the success rate is about 95%. However, there are known risks involved. The risks and their estimated incidence of occurrence are:
· Device dislodgement (embolization) and the need for emergency heart surgery – 1%
· Device erosion (device eroding through the heart walls) – 0.3%
· Death – <1% (usually from perforation of the heart chamber).
· Dislodgement of clot or air bubbles to the brain (causing stroke) and other organs <1%
· Rhythm disturbance (arrhythmia) are usually transient 1% -2%
· Other potential risks – Allergic dye reaction, anesthetic reaction, bleeding and bruising around the sheaths in the groin, injury to the artery/vein/nerves in the groin, perforation of the oesophagus (from the TEE probe), headache or migraine, infection, allergic reaction to the nickel component of the device

Some of these complications if they occur, are of a serious nature and may require further treatment including surgery and prolonged hospitalisation. In the event of device dislodgement, you may require surgery for removal of the device and closure of the hole at the same time. As ASD device is relatively new (i.e. Amplatzer ASD Device first used in 1995), long term follow-up data are not available and there may be other risks which are not known at this time.

Who is it for

Not all types of ASD are suitable for device closure. You will need to have a detailed echocardiogram scan including both transthoracic echocardiogram as well as a transoesophageal echocardiogram to assess if your defect is suitable for closure. Defects which do not have sufficient rims for the device to sit safely, defects which are too near to other heart structures such as veins, valves and very large defects (> 3.6cm) may not be suitable for device closure and may be better treated with surgery.