# Synchronised Cardioversion

## Overview

This module describes cardioversion, a lower energy shock which aims to cause a synchronised depolarisation throughout the heart tissue, enabling physiological conversion to sinus rhythm. It is delivered synchronous with the patient’s QRS complex to prevent R-on-T phenomenon, which could trigger ventricular fibrillation.

## Indications

1. Patients with tachycardia who are haemodynamically unstable

2. Patients with stable tachycardia—elective cardioversion

## Contraindications

1. None. Patients with pacemakers or other cardiac devices may also be cardioverted

## Patient information & consent

In emergency cardioversion, obtaining informed consent may not be possible. However, patients undergoing elective cardioversion need to give informed consent, and receive premedication for pain.

### How do I explain this procedure?

“Your heart is beating too fast and it’s affecting your blood pressure and circulation, making you ill. I need to give you a shock called cardioversion that will reset your heart rate and get it back to its normal speed. We may have to give you medications afterwards to keep it steady. The amount of electricity we use is very low, and will not cause any damage to your body. Because this is not an emergency procedure, you have to sign consent for it.”

### What can my patient expect?

“I’m going to give you an injection for pain and to make you drowsy, and then I’ll give you the mild shock. It might make your muscles jerk, but it will not be painful. We will be with you all the time and monitor you continuously.”

### What is my patient’s role?

“Tell me if you are allergic to any medications. Stay as calm as possible and cooperate with me.”

## Preparation

Follow the Tachycardia Management algorithm to this point. The patient should have:

1. An IV line

2. Continuous monitoring attached

3. Oxygen if indicated

4. Procedural sedation or analgesia only if haemodynamically safe

Synchronised cardioversion may be an emergency procedure. Always:

1. Know where defibrillators, transcutaneous pads, and red trolleys are kept. Know the relevant staff and keep your seniors’ contact details close at hand.

2. Familiarise yourself with the defibrillators in your work area. Check that they are maintained regularly and have pads and the correct connections.

3. Keep unstable patients in resuscitation bays with continuous monitoring.

## Site & Positioning

To perform synchronised cardioversion, a patient should be lying flat or reclining on a firm surface with their chest exposed. All clothes, including undergarments, should be removed from the chest.

## Procedure

Follow medical asepsis with non-sterile gloves.

1. Switch On the defibrillator to the manual defibrillation mode. Unless absolutely urgent, the patient will already have 3-lead monitoring attached, and you do not need to switch the Lead Select mode to Paddles.

2. Press the SYNC button. Check that you can see an indicator such an “S” or dot above complexes on the ECG tracing to ensure that the monitor is synchronised.

3. Face the machine. Lift the paddles and ask an assistant to apply conductive gel to the paddles.

4. Place the paddles on the chest, the paddle in your left hand at the right second intercostal space, and the paddle in your right hand on the left midaxillary line near the apex of the heart.

5. Ask an assistant to dial the energy up to 100 J.

6. Using your thumb, press the Charge button and call out, “Charging!”

7. Once charged, call out, “I’m clear, you’re clear, oxygen clear!”, ensuring that nobody is touching the patient and that all oxygen delivery devices are well away from the patient.

8. Call out, “Shocking!” and press-and-hold both index fingers on the Shock buttons on the paddles. Wait until a shock is delivered—there might be a short delay.

9. Call out, “Shock delivered!”

10. Analyse the ECG to determine if cardioversion was successful. If not, immediately repeat the procedure at 200 J, following the tachycardia algorithm.

11. If repeating shocks, note that some monitors default to defib mode, so you may have to press SYNC again. Alway check that you see an “S” or dot indicator above the QRS complexes on the monitor.

12. If repeated attempts fail to convert to or maintain sinus rhythm, switch to pharmacological options.

## Troubleshooting

The patient has a lot of breast tissue.

Always try to place paddles under or lateral to breasts. Large breasts can compromise the effectiveness of the shock delivered.

My patient is soaking wet.

Wipe the patient down quickly before applying paddles.

My patient is so hairy I can’t get contact with the skin.

Use a razor to shave the contact areas, or use any kind of adhesive dressing or pads to “wax” off the worst of the body hair.

My patient is wearing an underwire bra.

Cut it off. The current can run through the underwires, rendering it ineffective, and can cause burns.

My patient has a medication patch on their chest.

Remove it and wipe the area quickly.

My patient has an implanted pacemaker or defibrillator.

Don’t be deterred, but avoid placing your paddles on the device.

My patient is a small child.

Place one paddle on the right second intercostal space, and the other on the back, near the apex of the heart. Check the algorithm for paediatric joules and dosages.

The S or dot indicators are not appearing.

In most emergency settings, the monitor is programmed to default to defib mode. Check that you have activated SYNC mode.

The shock doesn’t deliver/the S or dot indicators are erratic.

The patient’s electrical activity may be too erratic due to ventricular extra-systoles or polymorphic ventricular tachycardia. Call a senior, or if the patient is very unstable with a barely palpable pulse, proceed with unsynchronised defibrillation.

The machine only has pads, not paddles.

Peel off the adhesive sections and stick them in place just like paddles. Keep them on throughout the cardioversion procedure.

Where do I place the three leads?

“Red on the right, green on the spleen, and what’s left on the left.” Place the red electrode on the right shoulder, yellow electrode on the left shoulder, and green electrode on the lower left torso.

I’ve charged, but I decided I don’t want to shock.

Ask an assistant to turn the defibrillator to Monitor instead of Defibrillation. This safely dumps the charge. Do not move charged paddles from the patient’s chest while this is being done.

How do I keep myself and my colleagues safe from electrical accidents?

- Always shout “Clear!” before shocking.
- Always keep oxygen sources at least an arm’s length away (oxygen + electricity can cause explosions).
- Paddles should always be firmly on the patient’s chest, or placed in their rests on the machine. Don’t put paddles down anywhere else.
- Never hold both paddles in one hand.

## Risks

1. Rhythm conversion to a pulseless rhythm

2. Burns & electrical injuries to patient

3. Burns & electrical injuries to healthcare providers

4. Explosions and medical fires due to oxygen exposure

## References

1. Resuscitation Council of Southern Africa. Tachycardia Management Algorithm. 2021.

2. Goyal A, Sciammarella JC, Chhabra L, et al. Synchronized Electrical Cardioversion. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482173/