Cardiac arrest is a condition in which the heart suddenly stops beating. It is different from a heart attack, which occurs when the blood supply to the heart is blocked. Whereas, in cardiac arrest, the heart stops functioning abruptly and the electrical function of the heart malfunctions. As a result, it does not pump the blood forward to the brain, lungs, and other organs. Without treatment, a patient may die within minutes.

The heartbeat may become irregular or stop entirely during cardiac arrest, a condition known as arrhythmia. The most common form of arrhythmia that occurs in cardiac arrest is ventricular fibrillation (VF). This condition needs immediate attention since the brain needs oxygenated blood to function. Under such circumstances, it cannot survive more than a few minutes without it, resulting either in permanent damage to part(s) of the brain or death. Cardiac arrest can occur at any time, but individuals with underlying pre-existing heart disorders are at risk of such incidences.

Causes of cardiac arrest

Cardiac arrest has numerous causes, and knowledge of these causes is very essential in both prevention and treatment.

• CAD: This is a condition where the heart's arteries get narrowed or blocked, which in most cases leads the victim to suffer a heart attack, has been found to be a very common cause of cardiac arrest.

• Myocardial infarction or heart attack: When the heart muscle is severely destroyed, cardiac arrest is caused by a severe heart attack. The critical interruption of blood flow will result in arrhythmia and could eventually become cardiac arrest.

• Arrhythmias: Rhythm disorders of the heart, ventricular fibrillation, and ventricular tachycardia are typically a direct trigger for the cause of cardiac arrest. In such disorders, the electrical system of the heart fails to work properly, including rapid and abnormal rhythms.

• Cardiomyopathy: This disease involves the thickening and enlargement of the heart's muscles, which leads to obstructions in the functioning of the pumping of the heart. Cardiomyopathy predisposes to arrhythmias and cardiac arrest.

• Congenital heart disease: Individuals born with heart disease are at risk of experiencing cardiac arrest due to the structural and electrical anomalies that cause disturbance in the heart.

• Electrolyte imbalance: Critical levels of important electrolytes, for example, potassium and magnesium, affect the electrical functioning of the heart, often causing arrhythmias and culminating in cardiac arrest.

• Drug overdose or poisoning: Drugs such as opioids and stimulants can also cause disastrous arrhythmias that eventually result in cardiac arrest.

• Extreme physical injury or gross bleeding: At times, extreme trauma or gross haemorrhage could cause the heart to stop and not pump blood within the normal rhythm, thereby causing cardiac arrest.

Cardiac arrest symptoms

Cardiac arrest usually arises without warning. Though often unremarkable, sometimes some symptoms may occur beforehand:

• Sudden collapse
• There is no pulse
• Chest pain
• Dizziness or lightheadedness
• Palpitations

Diagnosis of cardiac arrest

The diagnosis of cardiac arrest is fundamentally clinical. Thus, it's upon physical symptoms and lack of a heartbeat with breathing. However, the following tools can confirm the diagnosis:

• Electrocardiogram (ECG)
• Echocardiogram
• Coronary angiography

Treatment of cardiac arrest

Cardiac arrest treatment should start immediately. For every passing minute, the chances of survival continue to dwindle. The following are important components in the management of cardiac arrest:

• CPR: CPR is the first procedure and also the foremost one. Compressions on the chest are what keep the blood circulating into the brain and other parts as further medical attention is administered.

• Defibrillation: Defibrillation uses an AED, for instance, to shock the heart back to normal rhythm using electricity. Early defibrillation has greatly increased the chances of survival.

• ACLS: Emergency doctors can facilitate administering drugs, by intubating the patient to secure their airway and by appropriately re-initiating defibrillation when they arrive.

• Post-cardiac arrest care: If circulation is restored, the patient may be placed on ICU-level care, including cooling therapy, or therapeutic hypothermia to protect the brain and any interventions he/she may require to address the cause of the event.