On the day of your procedure you will wait on the ward and be made ready for the ablation. There are usually two to three cases on any given day; the order is determined by the consultant, based on many factors.
You may be prescribed a sedative (pre-medication) to be taken before you go to the catheter (cath) lab. Pre-medication, or "pre-med", is given to you to help you to relax ahead of a procedure and will usually be in tablet form.
Once the staff in the cath lab have called for you, you will be taken to the cardiology department and will wait outside the doors to cath lab, which is the room where the procedure takes place. You will be accompanied by a nurse from your ward, who will stay with you until you are taken into the cath lab.
You will be greeted at the cath lab doors by one of the multidisciplinary team (MDT), and you will be asked to confirm your name and some details; this is to make sure you are the right person.
The cath lab at Harefield Hospital
In the cath lab
In the lab you will meet all the members of the MDT. It is important that you talk to the member of the cath lab team. They understand that you may be anxious about the procedure and are happy to answer any questions to help reassure you.
Please be prepared to answer several very important questions, such as name, date of birth and if you have any allergies, multiple times. Female patients will be asked if there is any chance they could be pregnant to avoid X-rays harming the fetus.
As with any ablation procedure that involves access to the heart's left atrium, it is routine practice to administer a blood-thinning medicine, known as heparin, at the beginning of the procedure to reduce the risk of blood clot formation during the ablation procedure.
The anaesthetic assistant will check your details, and you will be transferred onto the on the cath lab bed. The bed is surrounded by large TV screens, X-ray tubes and all the technology and equipment needed for the procedure. You will be at the centre of attention as multiple items for monitoring are attached to you. The cardiac physiologist will stick some cold sticky patches on your back before helping you to lie down and make yourself comfortable.
The anaesthetist will then put a drip into a vein in your hand or arm, if you don't already have one, through which the anaesthetic can be given to send you to sleep. You may also be aware of them injecting some local anaesthetic into your wrist in order to place a small tube into an artery to allow close monitoring of your blood pressure. After this, you will receive some oxygen from a mask and the anaesthetist will start to give you the anaesthetic medication. Once you are asleep, a tube will be placed in your windpipe so that the anaesthetist can support your breathing during the procedure and further intravenous infusion lines (drips) will be inserted.
Under the anaesthetic
The next part of what is described happens while you are 'asleep' under a general anaesthetic.
Once you are asleep, a transoesphageal echocardiogram(TOE) will be performed to exclude a blood clot (thrombus) in the heart. The TOE uses an ultrasound probe (a long thin tube) that is placed into your oesophagus (food pipe) and helps us perform the procedure safely.
Using ultrasound we will make a detailed scan of your heart. If we see a thrombus (a blood clot), we will stop your procedure and reschedule it after you may had some more blood-thinning medication. The ultrasound probe will also monitor how well you heart is working during the procedure.
If you have any problems swallowing, please make sure that you tell your doctor this before the procedure as it may affect whether we use the probe or not. The TOE may also give you a sore throat and, in very rare cases, may damage the oesophagus.
We make small cuts (incisions) at the top of both legs and place three to five small tubes (less than 3mm) into the veins near the groin area. These tubes allow us to pass thin, flexible, specially shaped catheters (electrodes) and other slightly longer sheaths up to the heart.
We cross the electrical catheters from the right atrium into the left atrium through a small punctured hole (a transseptal puncture) made by a special needle. The catheters allow us to take pictures of the pulmonary veins and deliver the radiofrequency energy to the area around the veins. An advanced computer system, is used to create a 3D picture of the top of the heart. X-rays, ultrasound images and the electrical information, which comes from the electrodes being in contact with the chambers of the heart, are used to assess the electrical activity of each vein before and after ablation.
Ablation describes the process where we use the thin electrical catheter to "burn" the heart tissue to prevent short circuits occurring. This is like creating "fire breaks" around a forest fire to prevent it from spreading. We continue to ablate until we are sure we have created intact lines of ablated tissue. Just like in the forest, if the lines are not complete, the fire can spread.
When the consultant is satisfied that the pre-planned ablation strategy has been achieved, we will ensure you are in a normal rhythm or reset your heart to sinus rhythm using cardioversion.
Once in sinus rhythm, the catheters and sheaths are removed and manual pressure is applied to the entry site at the groin until any bleeding has stopped.
The length of your procedure will vary depending on factors such as how large your heart chambers are and whether you have paroxysmal or persistent AF. We usually find an ablation for paroxysmal AF takes two to four hours, whereas a procedure for persistent AF takes three to six hours.