External Cardioversion

External cardioversion is a medical procedure used to convert an abnormal heart rhythm (arrhythmia) back to a normal sinus rhythm using electrical shocks.

Indications

• Atrial fibrillation (AFib)
• Atrial flutter
• Supraventricular tachycardia (SVT)
• Ventricular tachycardia (VT)
• Other abnormal heart rhythms that are causing symptoms or putting the patient at risk

Preparation

Prior to the procedure, the patient will typically undergo:

• Electrocardiogram (ECG) to confirm the presence of an arrhythmia
• Chest X-ray to rule out any underlying lung disease
• Blood tests to check for any underlying conditions that may affect the procedure
• Anticoagulation therapy may be started to reduce the risk of blood clots
• The patient will be asked to fast for a certain period before the procedure

Procedure

The external cardioversion procedure typically involves:

• The patient lying on a bed or table in a supine position
• Electrodes (pads) being placed on the chest to deliver the electrical shock
• A defibrillator machine being used to deliver a controlled amount of electricity to the heart
• The patient being given a sedative or anesthetic to minimize discomfort and anxiety
• The procedure being performed by a trained healthcare professional, typically an electrophysiologist or cardiologist

Types of External Cardioversion

• Synchronized cardioversion: The electrical shock is delivered in sync with the patient's natural heartbeat
• Unsynchronized cardioversion (defibrillation): The electrical shock is delivered without regard to the patient's natural heartbeat, typically used in emergency situations

Risks and Complications

Possible risks and complications of external cardioversion include:

• Temporary redness or bruising at the electrode site
• Dizziness or lightheadedness
• Nausea or vomiting
• Headache
• Stroke or transient ischemic attack (TIA)
• Blood clots
• Cardiac tamponade (fluid accumulation in the sac surrounding the heart)

Success Rate

The success rate of external cardioversion varies depending on the type and duration of the arrhythmia, as well as the patient's overall health. Generally:

• Atrial fibrillation: 50-90% success rate
• Atrial flutter: 70-90% success rate
• Supraventricular tachycardia (SVT): 80-95% success rate
• Ventricular tachycardia (VT): 70-90% success rate

Post-Procedure Care

After the procedure, the patient will typically:

• Be monitored for a period of time to ensure the arrhythmia does not recur
• Undergo follow-up ECGs and blood tests to check for any complications
• Be prescribed anticoagulation therapy or anti-arrhythmic medications as needed
• Be advised to avoid strenuous activities for a certain period