The terms heart attack and cardiac arrest are often used interchangeably, but they describe two distinct, life-threatening medical emergencies. A heart attack is best described as a circulation problem within the heart’s muscular tissue, while cardiac arrest is an electrical failure of the heart’s rhythm. This distinction is crucial for a rapid and effective response, which can be the difference between survival and death.
Defining the Heart Attack
A heart attack, medically known as a Myocardial Infarction (MI), is primarily a plumbing problem, or a blockage that cuts off blood flow to a section of the heart muscle. This event occurs when a coronary artery, responsible for supplying oxygen-rich blood to the heart, becomes blocked, usually by a blood clot forming on ruptured plaque. The occlusion prevents oxygen and nutrients from reaching the downstream tissue, causing that part of the heart muscle to begin dying, a process called infarction.
Because the heart muscle is damaged but the heart’s electrical system is often still functional, the heart usually continues to beat during a heart attack. The primary symptoms reflect this circulatory distress and often develop gradually over minutes or hours, rather than occurring instantly. The most common sign is uncomfortable pressure, squeezing, or pain in the center of the chest that may last for more than a few minutes or disappear and return. This discomfort frequently radiates to the jaw, neck, back, or one or both arms, particularly the left. Other physical symptoms include shortness of breath, nausea, lightheadedness, or a cold sweat.
Defining Cardiac Arrest
Cardiac arrest, or Sudden Cardiac Arrest (SCA), is an electrical malfunction that causes the heart to abruptly stop beating effectively. The most common mechanism is ventricular fibrillation (VF), where the heart’s lower chambers quiver uselessly instead of contracting in a coordinated pump. When the heart enters this chaotic state, it cannot pump blood to the brain and other vital organs. The symptoms are instantaneous: the person suddenly collapses, becomes unresponsive, and shows no signs of normal breathing or a pulse. Consciousness is lost within seconds, and death can occur within minutes if the normal rhythm is not restored, as the lack of oxygen reaching the brain leads to irreversible damage quickly.
Immediate Emergency Response Differences
For a person experiencing a heart attack, the immediate action is to call emergency services. While waiting for help, the person should be kept calm and still, and if conscious and directed by emergency medical services (EMS), an aspirin may be administered to help inhibit blood clotting. The goal of this response is rapid transport to a hospital, where medical professionals can open the blocked artery using specialized interventions like a stent placement or clot-dissolving medications.
A person suffering cardiac arrest requires immediate, hands-on intervention to survive. The first action is to call EMS, but the next step must be to begin high-quality cardiopulmonary resuscitation (CPR). CPR provides manual chest compressions to circulate oxygenated blood to the brain and other organs until the heart’s electrical rhythm can be reset. The use of an Automated External Defibrillator (AED) is a time-sensitive necessity, as delivering an electrical shock is the only way to stop the chaotic ventricular fibrillation and allow the heart’s natural pacemaker to restart a normal rhythm.
When One Event Leads to the Other
A heart attack and cardiac arrest are often related, with the former frequently causing the latter. A heart attack damages the heart muscle tissue, and this injured area can lead to electrical instability. This instability can interfere with the heart’s normal signal pathways, triggering dangerous arrhythmias like ventricular fibrillation, which results in sudden cardiac arrest. However, cardiac arrest is not always preceded by a heart attack; it can be caused by other underlying conditions like heart failure, severe trauma, or electrocution.