Overview of Synchronized Electrical Cardioversion
Synchronized cardioversion is a procedure that is somewhat like a defibrillation. This process involves using an electric shock through the front part of your chest to stop a fast, irregular, and possibly life-threatening heart rhythm. Unlike defibrillation, which is used for patients who have a cardiac arrest (their heart has stopped), synchronized cardioversion is used for patients whose heart is still beating but is not pumping blood effectively. It is used to treat irregular heart rhythms that are coming from both lower and upper chambers of the heart.
Every year, nearly 350,000 Americans pass away due to heart disease. Half of these deaths happen suddenly, outside of a hospital, because of a sudden stop in regular heart activity. The most common reason for a sudden stop of the heart in adults is a heart rhythm disorder called ventricular tachycardia (VT) or ventricular fibrillation (VF), where the heart is not pumping effectively. VT can also occur when there is still a pulse; it often transitions into VF. VT shows up in heartbeat tracings as rapid, wide-waved signals.
Supraventricular Tachycardia (SVT) refers to a heart rhythm disorder where the heart beats faster than 100 beats per minute. This fast pacing comes from a part of the heart that is above an area called the ‘bundle of His’. SVT shows up as rapid, narrow signals in heartbeat tracings. Any rapid heart rhythm that isn’t coming from the lower chambers of the heart (ventricles) is referred to as SVT. This includes several heart rhythm disorders like sinus tachycardia, junctional tachycardia, reentrant tachycardias, multiple atrial tachycardia (MAT), and also the more known ones – atrial fibrillation, and atrial flutter. Even though there are various types of SVTs and they can be caused by different things, in practice, the approach to treatment is often the same.
Why do People Need Synchronized Electrical Cardioversion
Ventricular tachycardia (VT), a type of heart rhythm disorder, can occur due to various conditions. This includes coronary artery disease (which is a blockage in the heart’s blood vessels), hypertension (or high blood pressure), valvular heart disease (which is a condition involving the heart’s valves), and cardiomyopathy (a disease of the heart muscle). A strong hit to the chest, known as commotio cordis, can also trigger VT.
On the other hand, supraventricular tachycardia (SVT), another kind of heart rhythm disorder, is typically caused by a repeating circular movement of the heart’s electrical signal. Instead of moving down the usual path in the heart’s electrical system, the signal might go around in circles because of blocks in the system. Other causes of SVT are premature beats that start from the upper or lower chambers of the heart, stimulants that speed up the heart, thyroid conditions, heart valve and coronary artery diseases. Overdose of a heart medicine called digoxin can also lead to SVT.
When a Person Should Avoid Synchronized Electrical Cardioversion
No conditions would actually prevent someone from undergoing a process called synchronized cardioversion. Even if someone has a pacemaker or an automatic heart defibrillator – devices placed in the body to help control abnormal heart rhythms – these don’t interfere with or stop the procedure from being done.
Equipment used for Synchronized Electrical Cardioversion
A screen and a device used to restore normal heartbeat that can work in coordination with each other.
How is Synchronized Electrical Cardioversion performed
The American Heart Association has created guidelines to help healthcare professionals quickly identify and treat heart rhythms that are too fast, known as tachycardia. The first step is to recognize that the heart rhythm is faster than normal.
Afterward, the healthcare provider needs to figure out whether the heart rhythm is a narrow-complex tachycardia or wide-complex tachycardia. This is determined by the width of the QRS complex, which is a part of the heart rhythm that can be seen on a heart monitoring machine. If the QRS complex is less than 0.12 seconds, it’s considered narrow-complex tachycardia. This type generally originates from above the heart’s lower chambers and is often referred to as supraventricular tachycardias or SVTs. On the other hand, if the QRS complex is more than 0.12 seconds, it’s wide-complex tachycardia. These rhythms can originate from many places, but in emergency situations, they’re most often treated as if they originated from the ventricles (the heart’s lower chambers), as this condition can be life-threatening.
The next step is to figure out whether the patient has a pulse. If the patient doesn’t have a pulse, the healthcare provider will follow ACLS (Advanced Cardiovascular Life Support) protocols depending on whether the heart rhythm is narrow or wide complex. A wide-complex tachycardia without a pulse is treated as pulseless ventricular tachycardia, like a form of cardiac arrest called ventricular fibrillation (VF). A pulseless SVT, a narrow-complex tachycardia, is treated like pulseless electrical activity (PEA), another kind of cardiac arrest.
If the patient has a pulse, the healthcare provider has to determine if the patient is stable or unstable. In stable patients, medications are usually used to treat the irregular heart rhythm. If the patient is considered unstable and has symptoms like chest pain, difficulty breathing, confusion, low blood pressure, fluid in the lungs, or changes in their heart tracing, immediate treatment is required. This treatment is synchronized cardioversion, which delivers an electric shock to the heart to try to restore a normal rhythm.
Synchronized cardioversion is performed using a device called a defibrillator, which can deliver a shock through paddles placed on the chest or adhesive pads. Synchronized cardioversion differs from simple defibrillation in that it delivers the shock at a specific point in the heart’s electrical cycle to avoid causing another type of serious heart rhythm problem. It also typically requires less energy than defibrillation.
The healthcare provider sets the defibrillator to “synchronize” mode, which makes it track each heartbeat. When the shock is ready to be delivered, the defibrillator waits for the right moment in the heartbeat to deliver it.
The specific amount of energy used varies, but it’s often recommended to start at a low level (around 50 joules). If the initial shock doesn’t restore a normal heartbeat, the amount of energy is typically doubled until it’s successful, up to a maximum of 200 joules.
Possible Complications of Synchronized Electrical Cardioversion
Suppose you’re a patient with a type of abnormal heart rhythm called unstable SVT, and your heart suddenly stops (loses pulse). In that case, your treatment will follow the ACLS (Advanced Cardiovascular Life Support) guidelines for a condition known as PEA.
Similarly, if you’re a patient with another type of irregular heartbeat called unstable VT and your heart stops, the treatment would also change, following the ACLS guidelines, but this time for a condition known as VF.
In case your heart rhythm goes into VF, the medical device called a heart monitor/defibrillator, which tracks and regulates your heart rhythm, needs a quick change of settings. The device needs to be switched off from the “synchronise” mode, which looks for regular heartbeats (QRS complex). This change is necessary because the device won’t work properly to normalize the rhythm while still searching for regular heartbeats during VF — a situation where those regular beats don’t exist.
What Else Should I Know About Synchronized Electrical Cardioversion?
In layman’s terms, there are times when your heart can get out of sync, beating irregularly, which is called an arrhythmia. To fix this, doctors often use a procedure called synchronized electrical cardioversion. It’s like a reset button for your heart, helping it go back to its normal rhythm. This particular procedure is considered the most effective way to get many forms of irregular heartbeats back on track.
