What is an electrophysiological examination?
An electrophysiological examination (EPU for short) is always performed in a cardiac catheterization laboratory (then also called EPU laboratory). For the examination itself, special heart catheters are used, with the help of which an electrocardiological examination can be performed directly on the heart. If several of these cardiac catheters are positioned at specific points in the heart, the physician can precisely trace the conduction of the excitation and clarify cardiac arrhythmias in detail. In a sense, the examiner derives an ECG directly from the heart. In addition, during the EPU, stimuli can be set that cause hidden cardiac arrhythmias and thus make them detectable.
Cardiac arrhythmias
Subsequently, at the junction between the atria and ventricles, the impulse travels via the AV node and the His bundle to the ventricular legs (in the ventricular septum) and finally to the Purkinje fibers (in the ventricular muscles). They excite the myocardium from the apex, causing ventricular contraction. If the electrical signals are misdirected or additional impulses are generated in the heart wall, the heart rhythm is disturbed. The heart works in an uncoordinated way, so that the blood is pumped less effectively or, in the worst case, not at all into the body.
When is an electrophysiological examination performed?
The electrophysiological examination is primarily used for the precise clarification of a cardiac arrhythmia, which has usually been detected in a previous ECG or has caused symptoms such as palpitations. Today, EPU is used specifically for syncope diagnosis, particularly in patients with underlying cardiac disease. Electrophysiological examination is usually not an emergency examination, but is performed only after careful planning.
EPU is performed for the following types of cardiac arrhythmia:
- In individual cases, an EPU is also performed in the case of a bradycardia-tachycardia syndrome in order to clarify the underlying mechanism – but then only in connection with the possibility of curative catheter ablation.
- If there is a reasonable suspicion of sick-sinus syndrome – bradycardias originating in the sinus node – an EPU is occasionally performed.
- Tachycardic arrhythmias – the heart beats too fast: Causes include additional impulses in the walls of the atria (supraventricular tachycardia) or the ventricle (ventricular tachycardia). For tachyarrhythmias, EPU is indicated only in combination with catheter ablation.
- Seizure-like palpitations when symptomatology is suggestive of supraventricular tachycardia to identify the mechanism. These include, for example, atrioventricular reentry tachycardia (AVRT, including WPW syndrome) and AV nodal reentry tachycardia. Immediate treatment by catheter ablation usually follows.
- Cardiac arrhythmias in individuals without underlying cardiac disease who have survived sudden cardiac arrest.
What is done during an electrophysiological examination?
Before the electrophysiological examination, the doctor explains the benefits and risks to the patient in detail. You should not eat anything for about six hours before the examination begins, and you should not drink anything for four hours beforehand. Shortly before the EPU, a venous line is inserted through which medication and fluids can be administered (usually on the back of the hand). An ECG is used to monitor the heart rhythm throughout the EPU, and a finger sensor registers blood oxygen. Blood pressure is also measured regularly.
Patients are usually awake, but are given a sedative. The examiner numbs only the site where he wants to insert the catheters of the electrophysiological examination with a local anesthetic. Under this local anesthetic, the physician usually punctures the inguinal veins and places a so-called “lock” there. Like a valve, it prevents blood from escaping from the vessel and allows the catheters to be inserted.
If this is not successful, the catheters of the electrophysiological examination are inserted via the arterial system (arteries).
Once in the heart, the electrical signals that trigger the arrhythmias can now be registered at various points in the heart. This involves writing and interpreting an ECG directly from the heart (intracardiac). In some cases, the arrhythmias must first be triggered by electrical impulses from the catheters in order for the physician to determine their nature and origin.
Depending on how much is known about the patient’s arrhythmia prior to the electrophysiological study, the EPU will take different amounts of time. If multiple tests are needed, the EPU can be lengthy (about an hour).
What are the risks of an electrophysiological examination?
The electrophysiological examination is a safe procedure with few complications. Nevertheless, EPU irritates the heart and excitation system, which can cause atrial fibrillation, for example. Other possible complications are:
- Allergies to the local anesthetic or to other drugs
- @ Injury to vessels, nerves, skin and soft tissues
- Bleeding @
- Infections
- Blood clots (thromboses and embolisms) and stroke
- Bruises
- Wound healing disorder
Dangerous cardiac arrhythmias are rarely triggered unintentionally. Moreover, most of them can be corrected immediately during the electrophysiological examination. Nevertheless, to be on the safe side, an EPU lab has all the tools doctors need to perform cardiopulmonary resuscitation, if necessary.
What do I need to keep in mind after an electrophysiological examination?
You can usually go home just a few hours after the electrophysiological examination. However, you should avoid sports or other major exertion in the first few days after the EPU.
