Heart attack and cardiac arrest are often used interchangeably, yet they represent distinct medical emergencies affecting the heart. Understanding the differences between these two conditions is important for recognizing symptoms and initiating timely responses. Both are serious and require immediate medical attention, but their underlying causes and immediate dangers vary significantly.
Understanding a Heart Attack
A heart attack, medically known as a myocardial infarction, occurs when blood flow to a section of the heart muscle is blocked. This blockage results from plaque buildup in the coronary arteries, which supply oxygen-rich blood to the heart. When plaque ruptures, a blood clot can form, completely obstructing blood flow. If the blocked artery is not reopened quickly, the affected heart muscle begins to die from lack of oxygen.
Symptoms of a heart attack include chest pain or discomfort, which can feel like pressure, squeezing, or fullness. This pain might radiate to areas such as the jaw, neck, back, or arms. Other symptoms include shortness of breath, nausea, lightheadedness, and cold sweats. Symptoms can start slowly and be mild, or they can be sudden and intense. During a heart attack, the heart continues to beat.
Understanding Cardiac Arrest
Cardiac arrest is primarily an electrical problem within the heart, causing it to suddenly stop beating effectively. This cessation of pumping action leads to immediate loss of consciousness and collapse. While a heart attack is a circulation issue, it can sometimes trigger electrical disturbances that lead to cardiac arrest. Cardiac arrest can also occur independently due to other underlying heart conditions or electrical abnormalities.
The most common cause of cardiac arrest is an irregular heart rhythm called ventricular fibrillation, where the heart’s lower chambers quiver uselessly instead of pumping blood. This condition can be caused by coronary artery disease, heart attack, heart failure, or other arrhythmias. Symptoms are immediate, including sudden collapse, no pulse, and no breathing. Unlike a heart attack, cardiac arrest often occurs without warning, though some may experience chest discomfort or shortness of breath beforehand.
Distinguishing Between the Two
The fundamental difference between a heart attack and cardiac arrest lies in their underlying mechanisms. A heart attack is a “circulation problem” caused by a blockage in blood flow to the heart muscle. Cardiac arrest is an “electrical problem” where the heart’s electrical activity becomes chaotic, causing it to stop pumping. During a heart attack, the heart continues to beat and the person remains conscious. In contrast, during cardiac arrest, the heart ceases to beat, leading to immediate loss of consciousness and collapse.
Cardiac arrest presents a more immediate and severe threat because lack of blood flow to the brain and other organs can cause death or permanent brain damage within minutes. Survival rates for cardiac arrest are lower without immediate intervention, though prompt CPR and defibrillation improve outcomes. While a heart attack can be life-threatening and cause lasting heart damage, it is less immediately fatal than cardiac arrest. The time window for effective intervention is narrower for cardiac arrest, making it the more urgent emergency.
Emergency Response and Prognosis
Immediate action is necessary for both a heart attack and cardiac arrest. For a suspected heart attack, the primary response is to call 911 immediately. Prompt medical attention can maximize survival chances and minimize heart muscle damage. While waiting for emergency responders, keep the person calm and have them sit or lie down.
For cardiac arrest, the response must be even more rapid and direct. Calling 911 is the first step, followed by immediately initiating cardiopulmonary resuscitation (CPR). CPR helps maintain blood flow to the brain and other organs until professional medical help arrives. If an automated external defibrillator (AED) is available, it should be used quickly, as defibrillation can correct the erratic electrical activity that causes cardiac arrest. The prognosis for survivors of both events varies; however, the immediate and long-term consequences of cardiac arrest without prompt intervention are more severe due to rapid organ damage from lack of blood flow.