Catheter ablation is a minimally invasive procedure usually done by interventional cardiologists by which some abnormal heart rhythm is corrected.
In this procedure the area from which abnormal heart rhythm originates or the area where arrhythmia sustains are destroyed by using radio frequency ( heat ablation) or cryofreezing ( using cold), or the the path through which abnormal rhythm enters the heart is blocked by destroying the path.
Destroying this tissue helps restore the heart’s normal rhythm.
When pharmacological therapy of atrial fibrillation fails to work or when not tolerated or when there is recurrent attack of atrial fibrillation in spite of pharmacological therapy catheter ablation may be tried.
Indications of catheter ablation-
Cardiac ablation may be helpful in –
1 AVNRT ( Atrioventricular nodal reentrant tachycardia)
2 Accessory pathway
3 Atrial fibrillation and Atrial flutter
4 Ventricular tachycardia- a very fast and dangerous rhythm starts in lower chambers of heart.
Pulmonary veins play an important role in atrial fibrillation. Success rate of Pulmonary vein ablation for atrial fibrillation depends on several factors. It is more successful when there is no other cause of atrial fibrillation.
Patient may be totally cured after ablation. In some patients though not cured there is significant improvement with fewer and less intense attacks. Some patients may be responsive to previously used drugs after ablation which was ineffective before ablation. Some patients (20-30%) may need second time ablation.
Procedure of catheter ablation–
This procedure takes place in a hospital at the electrophysiology lab (EP) or catheterization lab ( cath lab).
Food or drinks to be stopped 8 hours prior to the procedure. Only medicines can be taken with sips of water if advised by doctor.
An Intravenous line is made in the forearm or hand through which drugs may be given
General anesthesia or local anesthesia may be given so that the patient cannot feel pain.
When general anesthesia or sedative takes effect a small area usually near a vein ( sometimes artery) on groin ( sometimes neck or forearm) is saved and if sedative is given then local anesthesia is given to numb that area.
A needle is inserted into the vein and a tube ( sheath) is placed through the needle. Several catheters are introduced through the sheath into the vessel to reach the specific area of the heart. such as a catheter with an electrode at the tip for radiofrequency ablation, a catheter for mapping electrical activity ( to see electrical activity in atrium and around pulmonary veins), a catheter for intracardiac USG.
Doctor may use video x-ray ( fluoroscopy) to see the heart and wires while doing the procedure or may use a special computer system to see the location of the catheters in the heart without using radiation.
The catheter with electrode is placed at the exact site from where abnormal activity originates. Then a radio frequency energy is sent to destroy the tissue. It destroys a very small area ( about1/5 inch).
When arrhythmia originates from a very small area then focal ablation is required. When it originates from a wide area then the wide area is destroyed by ablation and it is called ablation remodeling.
After catheter ablation-
After catheter ablation the patient rests in a recovery room for 4 to 6 hours. The sheath is usually kept for several hours. The patient should lie flat, hips not to be flexed. Heart rhythm, rate and blood pressure is monitored.
After removal of sheath pressure is applied on the puncture site to stop bleeding, legs are kept straight for 6 to 8 hours. As per advice from the the doctor the patient may be released on the same day or next day. Patient should not lift anything heavier than 10 Pounds at least for 10 days, should not drive or drink alcohol for 24 hours, should avoid physical activity for 3 days, and should not exercise until doctor tells him to do so.
If bleeding occurs, the patient should lie flat and ask somebody to press at the puncture site and call doctor or go to hospital if bleeding not controlled.
Patient should consult with doctor If any swelling, excessive pain or bleeding at the puncture site is noticed, if the leg becomes numb, feels cold or turns blue, if the puncture site begins to swell and fluid drains from it, if there is chest pain that radiates to neck, jaw or arm, if there is fast or irregular heart beat last for a long time, fever (100.4 degree F ) or more.
To determine the success of Procedure one should wait for 3 months because some people may still have short period of irregular heartbeat after the procedure, this is normal as tissue heels and should go away over time.
Risks of catheter ablation-
1 Bleeding or infection at the site where catheter was inserted
2 Blood vessels may be damaged by catheters during its movement through the vessels
3 Puncture of heart
4 Damage to heart valves
5 Pericarditis and pericardial effusion
6 It may worsen arrhythmia
7 Venous thromboembolism in legs and lungs
8 Stroke or heart attack
9 Pulmonary vein stenosis
10 Atrioesophageal fistula
11 Phrenic nerve injury
12 Damage to kidneys from dye if dye is used during the procedure.