What is catheter ablation?
Catheter ablation is a procedure where the section of heart tissue triggering abnormal electrical impulses is eliminated. An ablation catheter is passed along a vein to the location on the heart wall where the arrhythmia originates. Radio frequency electrical energy is transmitted through the catheter tip to the cardiac tissue to generate a tiny, exactly defined scar which will prevent future arrhythmias.
When is catheter ablation indicated?
Catheter ablation is indicated when arrhythmia causes harmful symptoms or is likely to pose a risk to your health. The need for catheter ablation is determined by a cardiologist specialising in the treatment of arrhythmias. The types of arrhythmia which can be treated include supraventricular tachycardia, atrial flutter, atrial fibrillation and ventricular tachycardia.Catheter ablation is always preceded by electrophysiological testing.
Preparations prior to operation
In the operating theatre, a nurse will insert an IV line in the back of your hand to allow for the administration of fluids and sedatives that will help you relax, if necessary. Self-adhesive electrode patches are placed on your chest for continuous ECG monitoring. Catheters are inserted via the veins in your groin. The insertion area is cleanly shaved. You will then be covered with sterile drapes.
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A local anesthetic is injected into your right groin area to numb the skin. Plastic sheaths
are then pushed into the veins. Soft, flexible examination and treatment tubes (catheters) are inserted through the sheaths and guided towards the heart along the inferior vena cava or aorta under X-ray guidance. First, the examination catheters are used to locate the source of the arrhythmia. This is called electrophysiological testing.
Catheter ablation is performed on the section of heart tissue where abnormal electrical impulses originate. If the dual atrioventricular node is the source of abnormal electrical impulses, ablation is targeted at the accessory section of the atrioventricular node located at the bottom of the right atrium (AVNRT). If the source of abnormal electrical impulses is caused by the presence of an abnormal accessory conduction pathway between the atria and the ventricles (WPW syndrome) treatment is targeted at the correct location. Atrial fibrillation is treated by isolating the pulmonary veins connected to the left atrium. The source of ventricular arrhythmia is on the ventricular wall.
When the target is in the left atrium, the treatment catheter is passed along the femoral vein and through the interatrial septum. This procedure is called a transseptal puncture, which is also applied to treat some abnormal accessory conduction pathways on the left side of the heart.
A different approach is applied when locating the exact target requires special equipment (CARTO®, EnSite®, Stereotaxis®). If catheter ablation might disrupt normal conductive function, another option is to use freezing (cryoablation) instead of radio frequency electrical energy. In cryoablation, catheters are passed in the same way as in catheter ablation. Freezing does not cause pain.
The procedure takes two to four hours.
After the operation
The examination and treatment catheters and sheaths are removed from the veins and firm pressure is applied to the small punctures in your veins to prevent bleeding.
Monitoring and care during catheter ablation
The procedure is carried out under local anesthetic. Sedatives are administered to help you relax. Additional sedatives and relaxants can be administered during the ablation procedure, if necessary. Pain caused by ablation therapy is managed by administering potent analgesics intravenously. These drugs are likely to be sedative and you may fall into a light sleep. Most arrhythmias cannot be detected while the patient is under general anesthetic and, therefore, it is only used in certain specific situations. Heparin is administered intravenously to reduce blood clotting, if necessary.
Complications
The risk of serious complications is small. Bleeding from the puncture sites may prolong the recovery period by a couple of days. Occasionally a bleeding puncture site may require surgical treatment. Abnormal vein location, vascular calcification, obesity and anticoagulant therapy increase the risk of bleeding.
Cardiac injuries are extremely rare. Should a catheter puncture the myocardium, bleeding into the pericardium could cause a serious situation (cardiac tamponation) which can be treated by removing the blood from the pericardium. Sometimes this requires cardiac surgery.
Injuries to conductive pathways near the targeted treatment site are rare. If a conductive pathway is injured, the condition is typically transient, but it might require the installation of a permanent pacemaker.Embolism and infections are highly unlikely complications of catheter ablation.
Discharge and follow-up
Patients are usually discharged on the same day as the operation or the next day. However, some patients may need to stay in hospital for a longer time.
Some patients may need total bedrest until the next morning.
On the day following the procedure, you can walk normally.
Driving is not allowed until the day after being discharged from the hospital.
Avoid heavy physical activity and sitting in a crouched position for the first one to two weeks. You will receive instructions on medications and advice on how to monitor your condition at home before you are discharged.