What is Synchronized Cardioversion?
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Article at a Glance
- Synchronized cardioversion is used during an unstable tachycardia with a pulse.
- To perform, the provider changes the monitor to the defibrillation mode, then presses the SYNC button.
- Synchronization avoids cardioversion during the refractory period.
- Energy is selected based on local protocols.
We use synchronized cardioversion for hemodynamically unstable tachycardias with a pulse still present. As providers, it’s our responsibility to know the equipment, so make sure you review your monitor and know how to perform synchronized cardioversions.Synchronized Cardioversion
Related Video – Tachycardia: Assessing the Clinical Condition
Related Video – Tachycardia: The Unstable Patient
Monitor Setup
Most monitors generally operate the same. First, select defibrillation, so the monitor readies itself to deliver a shock. Next, find the “sync” button. That puts the monitor into a synchronized state, so you can administer a synchronized shock.
On this cardiac monitor, the finger is pressing the sync button.
Synchronization means the defibrillator will administer an electrical shock, but not during the relative refractory period. Remember, during the QRS, the heart is depolarizing. During the T wave, the heart is repolarizing.
Related Video – ECG and the Cardiac Cycle Basics
Within the T wave are the absolute and relative refractory periods. The absolute refractory period is in the front half of the T-wave. During this state, there’s no way the heart can fire. It’s not chemically ready to discharge.
The relative refractory period occurs in the back half of the T wave. During this state, it may fire, but you don’t want it to because it can cause ventricular tachycardia.
The T wave consists of the absolute and relative refractory periods. Do not administer the shock during the relative refractory period during synchronized cardioversion.
During synchronized cardioversion, the monitor marks the R waves, so the machine does not deliver the shock during the relative refractory period. You’ll have to find and select the synchronize button, which should display hash marks above the QRS complexes to inform you the machine is in sync. The monitor should also say sync.
The hash marks above the QRS complexes are circled.
Next, select your energy level. The energy level varies anywhere from 50–100 joules depending on the patient’s rhythm. Look at the algorithm and follow your local protocols.
Read: Assessing Appropriateness for Clinical Condition
On most monitors, when you press the button to administer the shock, the monitor will time it out and administer the shock. In older units, you have to press and hold the button so the machine has time to sync up with the heartbeat and doesn’t administer the shock during the relative refractory period. Again, make sure you clear that patient, as you are administering an electrical current. Make sure the area is clear and no one is touching the patient before pressing the button and waiting for the shock. Clear the patient prior to administering the shock.Shock Administration
If a patient has a pulse and a hemodynamically unstable tachycardia, providers use synchronized cardioversion. On your monitor, select defibrillation and set it to sync mode. When it’s in synchronized mode, it won’t shock during the relative refractory period. Newer monitors will automatically fire. Alternatively, you have to hold down the button in older units, so the machine syncs up with the patient’s heartbeat. Summary
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