Rhythm Analysis for Cardiac Arrest

Introduction:

Cardiac arrests are heart emergencies in which the heart starts beating irregularly (irregular heart rhythms) and eventually stops beating. This abrupt heart function loss affects breathing and consciousness. It can also lead to death if emergency care is not provided. Prompt heart rhythm analysis, defibrillators, and cardiopulmonary resuscitation (CPR) can help restore normal heart rhythm and function.

What Happens in a Cardiac Arrest?

Various underlying heart conditions, heart tissue scars or damage, electrical abnormalities, thickened heart tissues, medications, drugs, and blood vessel abnormalities can result in sudden cardiac arrests. The electrical signal system of the heart begins to malfunction. This causes irregular heartbeats, also known as arrhythmias, which trigger cardiac arrest, and the heart unexpectedly stops beating. This is a medical emergency. The heart fails to pump blood to the body tissues and organs, including the brain and the lungs. Within seconds, the patient becomes unconscious and unresponsive and starts gasping for breath. Cardiac arrests lead to death within minutes if treatment is not initiated immediately.

What to Do if Someone Has a Cardiac Arrest?

Fluttering heart, weakness, shortness of breath, or chest discomfort may be seen before the patient collapses due to cardiac arrest. Sometimes cardiac arrest has no warning signs. We must suspect cardiac arrest if a person experiences the following:

• Becomes unconscious or does not react, move, blink or speak (loss of responsiveness).

• Gasps for breath or is not breathing.

• Collapses unexpectedly.

• Has no pulse.

In case of cardiac arrest, we must follow the following steps immediately till emergency service arrives to save the person:

1. Check for the patient's response after ensuring scene safety.

2. Call for help immediately (emergency medical services).

3. Arrange for an automated external defibrillator (AED).

4. Check the patient's breathing. If the person is not breathing or gasping, begin cardiopulmonary resuscitation (CPR) with compression.

5. Compress or push in the center of the patient’s chest (100 to 120 pushes per minute, around two inches deep). After every push, we must allow the chest to come back to its normal position.

6. Check the patient’s airway and deliver rescue breaths every 30 compressions (if trained in cardiopulmonary resuscitation). Just continue chest compressions if not trained.

7. Use the automated external defibrillator for rhythm check and shock delivery and continue cardiopulmonary resuscitation until help arrives.

What Are the Heart Rhythms Seen in Cardiac Arrest?

The heart rhythms must be monitored in cardiac arrest to manage the patient accordingly. There are some types of heart rhythms that require shock (defibrillation) and some rhythms that do not require shock administration. Quick, immediate action based on the heart rhythm is necessary to manage cardiac arrests. There are four basic types of heart rhythm seen in cardiac arrests:

1. Ventricular Fibrillation (VF): This type of rhythm, also known as V-Fib, is the most serious in cardiac arrests. There are disorganized electrical impulses in the heart muscles. The muscles of the heart’s lower chambers or ventricles begin to flutter or fibrillate instead of beating normally. The heart beats with a rapid and erratic rhythm. As a result, the heart finds it difficult to pump blood, causing cardiac arrest.

2. Pulseless Ventricular Tachycardia (VT): The lower chambers of the heart (ventricles) start to beat fast or with rapid rhythmic contractions. As a result, the heart beats too fast to pump blood.

3. Pulseless Electrical Activity (PEA): The heart is not able to beat sufficiently to produce a detectable pulse.

4. Asystole: This rhythm indicates the absence of electrical activity in the heart.

How Is Cardiac Arrest Managed Based on Heart Rhythm Analysis?

Cardiac rhythm analysis helps guide the management of cardiac arrest emergencies. The interruptions during cardiopulmonary resuscitation should be kept as short as possible. The key is to stop only for heart rhythm analysis and pulse check and to administer a shock if needed between the chest compressions. The four rhythms seen in cardiac arrest are divided into two groups - shockable and non-shockable rhythms. The electrocardiogram (ECG) helps distinguish between these rhythms. Ventricular fibrillation and pulseless ventricular tachycardia are cardiac rhythms that can be reversed by defibrillation or shock. Pulseless electrical activity and asystole (when the heart stops completely, no electrical activity) do not require shock during cardiopulmonary resuscitation. During cardiopulmonary resuscitation, the heart rhythm changes frequently. The management must be modified based on the rhythm immediately.

How Are the Non-shockable Rhythms Managed in Cardiac Arrest?

The heart rhythms such as asystole and pulseless electrical activity do not require defibrillation or shock. In such a case, cardiopulmonary resuscitation must be performed immediately with rhythm analysis every two minutes. This is continued till we attain an organized heart rhythm. The pulse is then checked every two minutes of chest compressions. Quality cardiopulmonary resuscitation must be continued till we attain a pulse. Drugs such as Vasopressors to increase blood flow to the heart and brain are administered, and airway management interventions are initiated to improve the chance of the return to spontaneous circulation (normal blood flow).

What Are Defibrillators?

Defibrillators are devices that are used to deliver electric shocks (defibrillation) through the chest to the heart of a person with shockable rhythms, such as ventricular fibrillation and pulseless ventricular tachycardia. The electrical shock or defibrillation helps to stop the irregular rhythm of the heart and restarts the heart with a regular organized rhythm or normal heartbeat. Defibrillation, along with immediate chest compression, must be initiated quickly within the first three to ten minutes of cardiac arrest. The person’s chance of surviving drops by seven to ten percent for every minute a normal heartbeat is not restored. There are two basic types of defibrillators used during an emergency. These are:

1. Automated External Defibrillators (AED): These are portable, small, and lightweight devices that are used to deliver an electric shock to the heart through the chest. These can be used by anyone with little training. These devices can be used at home and are found in schools and public places so that the resuscitation process can be initiated immediately following a cardiac arrest. These devices automatically perform the heart rhythm analysis, so the operators do not need to read or interpret the patient’s heart rhythm. They are automated and detect irregular heart rhythms. They deliver controlled shock to the patients with shockable rhythms. In the case of non-shockable rhythms, no shock is delivered by the device.

2. Manual Defibrillators: These are used by medical professionals trained in advanced cardiac life support. They offer greater control and customization (of the shock delivered). In addition, they can be connected to other medical devices to monitor blood oxygen levels, blood pressure, and carbon dioxide exhaled. They can also provide pulses of current that help the heart contract and restore normal heart rhythm.

How to Use Automated External Defibrillators?

Immediate cardiopulmonary resuscitation has to be performed in case of cardiac arrest. The automated external defibrillators automatically analyze the heart rhythm, and it has to be performed every two minutes of cardiopulmonary resuscitation. In case the device detects shockable rhythms, it will charge spontaneously and prompt the operator to clear when it delivers the shock. After defibrillation, the chest compressions for cardiopulmonary resuscitation have to be resumed for another two minutes, and the process has to be continued until the heartbeat is back to normal or emergency help arrives.

Conclusion:

Cardiac arrests are life-threatening emergencies that require immediate medical attention. Heart rhythm-based management of cardiac arrest helps restore the normal regular heartbeat and pulse. Cardiopulmonary resuscitation can be initiated by lay rescuers with the help of automated external defibrillators. These automated devices perform rhythm analysis and initiate shock delivery for shockable rhythms. Electrical shocks with chest compressions have to be initiated as soon as possible and must be continued until emergency help arrives.