Understanding Cardioversion | Wellbeing

What are Defibrillation and Synchronized Cardioversion?

Defibrillation is a medical treatment method that uses a high-energy shock released over a very short period to restore a normal heart rhythm from an arrhythmia state. After the electric shock, the sinus node takes control, and the heart can resume functioning naturally and rhythmically. This method is often performed using external defibrillators in manual, automatic, or semi-automatic forms.

Some types of defibrillators can be used in open-heart surgery, with electrodes applied directly to the heart. Additionally, there are some types of cardioverter-defibrillators implanted into the body. The main purpose is to treat heart rhythm disorders such as atrial fibrillation, ventricular tachycardia, or ventricular fibrillation.

Synchronized cardioversion is a defibrillation method where the electric pulse strikes the R wave of the QRS complex. The QRS complex represents the depolarization process of the ventricles. The Q wave is the first negative wave of the QRS complex, the R wave is the first positive wave of the complex, and the negative wave following it is S; these are two waves formed by ventricular depolarization.

Operating Principle of Synchronized Cardioversion

Synchronized cardioversion uses a controlled electric shock with a high energy current released over a short period to simultaneously depolarize myocardial cells. This helps stop abnormal heart rhythm activity, allowing the heart's natural electrical conduction system to return to normal operation.

Synchronized cardioversion synchronizes with the QRS complex (targeting the R wave). When the Sync button is pressed on the defibrillator, the machine will automatically track the QRS complex and mark the position where electricity will be discharged.

How to Perform Synchronized Cardioversion

If the cardioversion is planned, the patient needs to fast for 6-8 hours. Short general anesthesia is required because the procedure can cause pain to the patient. There must be equipment and personnel to maintain the airway and circulation.

Defibrillator paddles can be placed in the anterior-posterior position (one paddle at the 3rd-4th intercostal space near the left sternal border, one paddle under the left shoulder blade), or the anterior-lateral position (one paddle at the 2nd intercostal space near the right sternal border, one paddle at the 5th-6th intercostal space at the apex of the heart). After the defibrillator shows signs of the shock synchronizing with the QRS complex, the performing doctor will press the discharge button.

Select the energy level suitable for the type of tachycardia. Apply conductive gel to the paddle surface, place on the patient's chest in the correct position, observe the ECG on the screen, and select the lead with the clearest R wave. When the discharge button is pressed, energy will accumulate and wait for the exact moment of the QRS complex to discharge. Subsequent shocks use equivalent or higher energy levels. In open-heart surgery, defibrillator paddles placed directly on the heart can be used; however, these cases use lower energy levels.

Indications and Some Complications with Synchronized Cardioversion

Synchronized cardioversion is mainly indicated in cases of: Atrial fibrillation, ventricular tachycardia, and types of arrhythmias causing hemodynamic instability. Some cases require consideration when performing cardioversion such as asymptomatic atrial fibrillation or atrial flutter, atrial fibrillation with slow ventricular response, sick sinus syndrome, or pathology regarding the conduction system in the heart. After synchronized cardioversion, the patient needs to be monitored closely.

Synchronized cardioversion is a method with specific indications and is relatively safe. However, there are still complications such as hypotension, respiratory failure due to sedatives, atrial or ventricular arrhythmias, pulmonary edema, myocardial injury, skin burns, etc.

Synchronized cardioversion is an effective and life-saving method in treating serious heart rhythm disorders. Understanding the procedure, indications, and potential complications will help patients and relatives have the best preparation before undergoing this procedure. If you or a relative are experiencing heart rhythm problems, consult a doctor for more information and to choose the appropriate treatment method.

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