What is electrophysiological testing?
Electrophysiological testing refers to an examination where cardiac arrhythmias are studied from the inside of the heart. It is used to determine if your symptoms are caused by arrhythmia, and if yes, their type, location of origin and severity. The best possible treatment is determined based on the test results. Possible alternatives include drug therapy, catheter ablation and pacemaker therapy. Sometimes knowing the characteristics of arrhythmia is sufficient and no treatment is required.
When is electrophysiological testing indicated?
Electrophysiological testing is indicated when arrhythmia causes serious symptoms or is considered a risk to the patient's health. Serious symptoms include recurring sudden attacks of tachycardia, sudden loss of consciousness and chest pain during cardiac palpitations.The need for electrophysiological testing is determined by a cardiologist specialising in the treatment of arrhythmias.
Examinations preceding EP testing
Before electrophysiological testing, your heart's condition will be examined using other methods, including resting ECG, exercise ECG and 24-hour ECG recording (Holter monitoring). An echocardiogram may also be taken. Sometimes, coronary angiography is performed in connection with EP testing.
Preparations prior to examination
In the operating theatre, a nurse will insert an IV line into 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.
What happens during EP testing?
Your heart is accessed through the great veins (usually the femoral vein, sometimes the femoral artery). A local anesthetic is injected into your groin area to numb the skin and sheaths are pushed into the femoral vein. Soft, flexible tubes (catheters) are inserted through the sheaths and guided towards the heart along the inferior vena cava under X-ray guidance. You do not feel any pain when the catheters move along the vein and are positioned in the heart. At the other end, the catheters are connected to a computer to examine arrhythmias.
Electrophysiological testing is performed to study how electrical impulses travel in your heart during sinus rhythm, pacing and arrhythmia. Your heart is paced for a few seconds using variable speeds to generate extra beats. A short pause is held between each pacing sequence. Your overall condition, blood pressure, heart rate and electrical signals transmitted from the heart are continuously monitored to detect the location of any accessory electrical impulses and any accessory conduction pathways (e.g. accessory congenital conduction pathway).
The purpose of testing is to generate arrhythmia to be able to reliably determine the origin and type of arrhythmia. Arrhythmia can be quickly stopped by pacing the heart
with the electrodes located at the tips of the catheters. Atrial fibrillation may sometimes require electrical cardioversion which is performed under general anesthetic.
Electrical cardioversion is also used to stop dangerous ventricular arrhythmia in patients with existing heart disease.
After the test, the results and any findings are communicated to the patient. The best possible treatment can be determined immediately after the examination.
Some arrhythmias can be treated during EP testing using catheter ablation. However, if special equipment is required or there are risks involved, catheter ablation is performed later. If required, a pacemaker can also be installed later.
Monitoring and care during EP testing
The procedure is carried out under local anesthetic. Sedatives are administered to help you relax. Additional sedatives and relaxants can be administered during the test, if necessary. When catheter ablation is performed during EP testing, 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.
After EP testing
The catheters and sheaths are removed and firm pressure is applied to the small punctures in your veins to prevent bleeding.
Complications
The risk of dangerous complications is very 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 tamponade) which can be treated by removing the blood from the pericardium. Sometimes this requires cardiac surgery. Embolism and infections are highly unlikely complications of EP testing.
Discharge and follow-up
Patients are usually discharged on the same day as the operation. However, some patients need to be monitored in hospital overnight. On the day following the procedure, you can walk normally. Driving is not allowed until the day after being discharged. Avoid heavy physical activity and sitting in a crouched position for the first one to two weeks. No other follow-up care is required. You will receive instructions on medications and advice on how to monitor your condition at home before you are discharged.