Why is cardioversion important?
Cardioversion is an important medical procedure for restoring the sinus rhythm in the case of serious arrhythmias which may be life-threatening or which, in the case of atrial fibrillation, increase the risk of blood clots and strokes if untreated.
Electrical cardioversion has a much higher success rate than treatment with antiarrhythmic drugs. According to the Deutsches Ärzteblatt journal, pharmacological cardioversion produces a sinus rhythm in around 70% of patients while the figure is more than 85%2 with electrical cardioversion.
Other studies come to similar conclusions and also demonstrate that the treatment duration in cases such as acute atrial fibrillation is much shorter with electrical cardioversion than with pharmacological cardioversion3.
How do you perform a cardioversion?
If a cardioversion is performed electively, anticoagulant medication is administered beforehand both with pharmacological and electrical cardioversion. This is important as thrombi (blood clots) often form in the atria particularly with patients with atrial fibrillation. These thrombi can lead to an embolism through to a stroke.
A transesophageal echocardiogram (TEE) is also performed before a cardioversion to rule out intraatrial thrombi.
A pharmacological cardioversion is only used with hemodynamic stable patients and usually only electively. The antiarrhythmic drug is administered orally or intravenously. Depending on the drug’s mechanism of action, the active ingredient blocks certain receptors relevant for nerve conduction or blocks ion channels so that the heart activity is normalized and the sinus rhythm restored.
An electrical cardioversion is used on an outpatient basis as an elective procedure or as an emergency treatment with antiarrhythmic drug-resistant ventricular tachycardia. In both cases, the treatment is performed under short anesthesia using a defibrillator and is monitored via an ECG. The defibrillator delivers an electrical shock of 125 to 200 joules synchronously with an R wave – depending on the indication. If delivery of a single shock is not sufficient to restore the sinus rhythm, a second shock with higher energy is delivered.
The recommendation for patients at particular risk of stroke or recurrence is to keep taking anticoagulants for several weeks after the electrical cardioversion.
Cardioversion is a safe procedure with few side-effects. These include:
- Arrhythmias (e.g., asystole or ventricular tachycardia)
- Embolisms due to released blood clots through to a stroke