Overview of Defibrillation

Cardiac defibrillation is a treatment given to a person who is experiencing a life-threatening heart rhythm problem called either ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). These issues involve fast and uncontrolled heartbeats. The Advanced Cardiac Life Support (ACLS) guidelines treat these two conditions in the same way.

According to the Centers for Disease Control and Prevention (CDC), 610,000 people die every year in the United States due to heart disease. This makes it the leading cause of death for both men and women. About half of these sudden heart attacks happen outside of a hospital setting and three out of four times, these events occur at home without any witnesses. VF is the most common reason for these sudden heart attacks in adults.

The best way to treat VF is by using a defibrillator which administers an electric shock to the heart. This treatment works best when it is used as soon after the onset of the VF as possible. For every minute that defibrillation is delayed, it becomes nearly 10% less effective.

The survival rate of adults who have a non-trauma related cardiac arrest and receive treatment from emergency medical services has been found to be 10.8%. However, if the cardiac arrest occurs when they are already in a hospital, this survival rate increases to 25.5%. This is likely because the defibrillation treatment can be administered sooner in a hospital setting.

Anatomy and Physiology of Defibrillation

Ventricular fibrillation is a serious heart condition that happens when the normal electrical signals that control your heartbeat become chaotic. It usually happens during a heart attack or when there’s a sudden disruption to those heart signals. It can also be caused by conditions like abnormal heart rhythms or medical syndromes that extend the time between heartbeats.

When these chaotic electric signals fire from multiple points in the lower chambers of your heart, known as ventricles, it causes their rapid, irregular shaking, or “fibrillation”. This prevents your heart from pumping blood properly, leading to a sudden cardiac arrest, which is a medical emergency.

Defibrillation, using an electric shock, can be an effective treatment, but time plays a critical role. This is because if left untreated, VF can quickly worsen into a condition called asystole, where the heart stops beating and chances of survival drop significantly. For every minute VF or VT remains untreated, the chances of successful resuscitation decrease by about 10% per minute. However, performing Cardiopulmonary Resuscitation (CPR), which is a lifesaving technique involving chest compressions and rescue breathing, can help provide temporary oxygen and blood flow until defibrillation becomes available. Properly executed, CPR could provide almost a third of the normal blood flow and oxygen levels for the body, potentially tripling the survival rate from sudden cardiac arrest.

The best treatment for VF or similar conditions is electrical defibrillation. Contrary to popular belief, defibrillation doesn’t “jump-start” the heart. Instead, it causes almost all of the heart muscle to activate at the same time, momentarily stopping all heart activity. Ideally, a healthy part of the heart’s built-in electrical system will then start a new electrical pulse that can restore a normal heartbeat, which means blood can be pumped around the body again. Though defibrillation is usually done by healthcare professionals, Automated External Defibrillators (AEDs) now allow even non-medical persons to provide early defibrillation to victims of sudden cardiac arrest. These devices can automatically read the heart rhythm, decide if a shock is necessary, and guide the person to successfully defibrillate.

Why do People Need Defibrillation

If your heart is beating in an abnormal pattern called ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT), and it causes you to lose your pulse, the best treatment is a procedure called early electrical defibrillation. This procedure uses an electric shock to help your heart return to its normal rhythm.

When a Person Should Avoid Defibrillation

Defibrillation, a procedure used to help the heart beat normally, can be used on anyone. It doesn’t matter if a person has a special device like a pacemaker or an implanted cardiac defibrillator, which are used to regulate heart rhythms. These devices don’t affect the need or ability to perform defibrillation if the heart is beating abnormally and needs to be corrected.

Equipment used for Defibrillation

In order to perform a procedure called defibrillation, which restores a normal heartbeat, a machine called a cardiac monitor with the ability to do defibrillation or an automated external defibrillator (AED), is needed. AEDs are portable devices that can automatically check the heart rhythm and, if needed, send an electric shock to the heart to restore a normal rhythm.

Who is needed to perform Defibrillation?

Defibrillation is usually done by medical professionals who have gone beyond their basic training. They have taken extra classes in how to revive someone’s heart. These classes might include programs like ACLS (Advanced Cardiac Life Support) or PALS (Pediatric Advanced Life Support), which are specifically designed to teach life-saving procedures for adults or children respectively.

Preparing for Defibrillation

While the defibrillator is being readied, resuscitation efforts, including CPR (Cardiopulmonary Resuscitation), are carried out. CPR is a procedure that uses chest compressions and artificial breathing to help a person whose heartbeat or breathing has stopped.

When a defibrillator becomes available, it’s crucial to use it as soon as possible. This machine is essential and takes priority over other lifesaving measures if the patient’s heart is beating too fast (VT or Ventricular Tachycardia) or irregularly (VF or Ventricular Fibrillation). These are dangerous conditions which can cause the heart to stop.

Using a defibrillator involves delivering an electric shock across the patient’s chest. This can be done by placing a pair of manual paddles on the chest, or by applying sticky pads that don’t require hands to hold them in place. The electric shock can help the heart return to its normal rhythm.

Most modern defibrillators use a ‘biphasic waveform’. This technology requires less power to work effectively and is a better choice for stopping irregular heartbeats. This makes devices that use a biphasic waveform more desirable than those using the older, ‘monophasic waveform’ version.

How is Defibrillation performed

The defibrillator is a machine used during medical emergencies to send an electric shock to the heart, helping it get back to its normal rhythm. These electric shocks are administered using paddles or ‘hands-free’ adhesive pads, which can be placed in two spots – one along the upper right side of your chest and the other on the tip of your heart or your cardiac apex.

The defibrillator gets ready to send the shock by charging up, all while being in a mode specifically meant for sending these electric shocks. The energy level for the shock differs depending on the defibrillator with most requiring between 120 and 200 joules, and some needing 360 joules. If the defibrillator’s usual energy level isn’t available for some reason, the highest energy level possible should be used.

Just before the shock is sent, the people around the patient need to make sure they are not touching the patient or anything that’s touching the patient. Then, the defibrillator will send the electric charge from one paddle or pad to the other through the patient’s chest. After the shock has been given, the resuscitation (CPR) should begin again for two minutes. After these two minutes, the medical team will check the patient’s pulse and the heart’s electrical rhythm on the monitor to see if the first defibrillation was successful or not.

If the original condition (VF or pulseless VT) persists, the doctors will continue the resuscitation and might give the patient an additional shock. This process might continue, and with each electric shock, the energy level might get increased. Alongside, certain medications might be given as well, like a dose of epinephrine (an adrenaline hormone) after the first unsuccessful shock, and amiodarone or lidocaine if needed, to help the heart regain its normal rhythm.

The procedure for children is slightly different. The energy used for the shocks is usually smaller- initially 2 joules/kg and then 4 joules/kg or more, and not more than 10 joules/kg. If the patient is a baby younger than 1 year or weighs less than 10 kg, smaller-sized pads are used. But, if these aren’t available, adult pads can be used carefully so as not to touch each other. Also, the defibrillator used for babies should ideally be a manual one. If there is none available, a pediatric attenuator, which adjusts the electric shocks according to a child’s size, can be used.

Internal defibrillation might be necessary during certain surgeries like emergency room thoracotomy or heart surgeries. This is similar to external defibrillation, but the energy used is less (20 joules and then up to 40 joules) to prevent burn-like injuries to the heart. During this, special care is taken to avoid damaging the vessels of the heart. Sterile internal pads are used for this and are always kept ready during any surgery involving opening the chest.

Possible Complications of Defibrillation

When a person is given an electric shock to restart their heart, also known as defibrillation, the energy is released instantly. The shock is given no matter where the heart is in its cycle of beat. If a person who doesn’t need defibrillation gets it, the shock might hit at a fragile time during the heart’s cycle and cause a dangerous heart rhythm, known as Ventricular Fibrillation (VF) or pulseless Ventricular Tachycardia (VT), putting the heart into cardiac arrest. So, defibrillation is used only when VF or pulseless VT are present.

If a patient’s heart is beating irregularly but they are not in cardiac arrest, a different procedure called synchronized cardioversion is done to avoid complications. In simpler terms, this means the shock is timed to a specific part of the heart’s cycle, reducing the risk of triggering cardiac arrest.

For a patient with a certain type of irregular heart rhythm called ventricular tachycardia who has symptoms of low blood flow and unstable heartbeat, synchronized cardioversion using an energy dose of 100 joules is recommended.

What Else Should I Know About Defibrillation?

Ventricular Fibrillation (VF) is a serious heart condition where the heart’s lower chambers quiver, and the heart can’t pump any blood, causing a cardiac arrest. The best way to treat VF is to use a process called defibrillation as soon as possible after the condition starts. Defibrillation is a treatment that involves delivering an electrical shock to the heart, which helps to restore its normal rhythm.

It’s important to note that, if more than 10 minutes pass from the start of VF without defibrillation, the chances of bringing the patient back drop significantly, almost to zero. Therefore, in many neighborhoods, programs have been set up to teach certain community members how to use an Automated External Defibrillator (AED) to provide defibrillation. An AED is a portable device that checks the heart rhythm and can send an electric shock to the heart to restore a normal rhythm.

Frequently asked questions

1. How soon after the onset of ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) should defibrillation be administered for the best chance of success? 2. What is the survival rate for adults who receive defibrillation treatment from emergency medical services versus those who receive treatment in a hospital setting? 3. Can defibrillation be performed on anyone, regardless of whether they have a pacemaker or implanted cardiac defibrillator? 4. What is the difference between a biphasic waveform and a monophasic waveform in defibrillators, and why is the biphasic waveform considered more desirable? 5. What is the procedure for defibrillation, including the placement of paddles or adhesive pads and the energy level used for the shock?

Defibrillation can be an effective treatment for ventricular fibrillation (VF) or similar conditions. It causes almost all of the heart muscle to activate at the same time, momentarily stopping all heart activity. This can potentially restore a normal heartbeat and allow blood to be pumped around the body again.

You would need defibrillation if your heart is beating abnormally and needs to be corrected. It doesn't matter if you have a special device like a pacemaker or an implanted cardiac defibrillator, defibrillation can still be used to help your heart beat normally.

You should not get defibrillation if your heart is beating normally and does not require correction, regardless of whether you have a pacemaker or implanted cardiac defibrillator. These devices do not affect the need or ability to perform defibrillation.

To prepare for defibrillation, the patient should ensure that they are not touching the patient or anything that's touching the patient just before the shock is sent. The defibrillator will then send the electric charge from one paddle or pad to the other through the patient's chest. After the shock has been given, resuscitation (CPR) should begin again for two minutes.

The complications of defibrillation include the risk of causing a dangerous heart rhythm, known as Ventricular Fibrillation (VF) or pulseless Ventricular Tachycardia (VT), if the shock is given to a person who doesn't need it. This can put the heart into cardiac arrest. Therefore, defibrillation is only used when VF or pulseless VT are present. To avoid complications, if a patient's heart is beating irregularly but they are not in cardiac arrest, a different procedure called synchronized cardioversion is done. This procedure times the shock to a specific part of the heart's cycle, reducing the risk of triggering cardiac arrest.

The symptoms that require defibrillation are an abnormal heart rhythm called ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT), which causes the person to lose their pulse. In these cases, early electrical defibrillation is the best treatment to help the heart return to its normal rhythm.

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