January 2, 2023 Author : José Ferreira Santos A cardiac arrest and a myocardial infarction are not the same thing. In cardiac arrest , the heart has stopped working and pumping blood. Myocardial infarction is related to a problem in the blood supply to the heart, which leads to the death of the heart muscle. Cardiac arrest What happens in cardiac arrest? A cardiac arrest is a sudden event, which can occur without warning signs. The heart is no longer able to pump blood to the brain, lungs and other organs and tissues in the body. A person in cardiac arrest loses consciousness (faints), stops breathing, and has no pulse because the heart stops beating. If not helped quickly, death is a certainty! Why does cardiac arrest happen? For the heart to contract and pump blood, it needs constant electrical stimuli and functioning muscle. Cardiac arrest can arise for two main reasons : The heart stops producing adequate electrical stimuli for its functioning. In this case, the electrical activity becomes unpredictable and chaotic, and an arrhythmia called ventricular fibrillation develops, in which the heart stops working automatically; The heart can also stop working because the muscle has stopped working and the heartbeat is no longer effective. This can happen when there is an extensive myocardial infarction, a sudden pericardial effusion (fluid around the heart) or a massive pulmonary embolism, among others. In these cases, and in a first phase, the electrical activity of the heart may be maintained, but inevitably, if nothing is done, the heart will also end up having no electrical activity. There are several causes of cardiac arrest , the most common are: Acute myocardial infarction; Hypertrophic cardiomyopathy (and other cardiomyopathies); Cardiac insufficiency; Congenital heart diseases; Electrical heart diseases (like brugada syndrome, long QT syndrome, among others); Severe trauma, drowning or electrocution; Consumption of recreational drugs, such as cocaine, methamphetamines, among others. What to do in case of cardiac arrest? When cardiac arrest occurs, it is necessary to intervene immediately, namely : Confirm that the victim is unconscious and call 112 for help; Start basic life support , with chest compressions (cardiac massage) that allow the blood to continue circulating, even when the heart is stopped. If you have equipment and know how to do it, ventilations for blood oxygenation should also be performed; As soon as possible, a defibrillator should be used, which allows administering an electric shock to treat ventricular fibrillation and restore the heart normal electrical activity. Many public spaces already have automated external defibrillators, but in Portugal it is necessary to have training for their use by non-medical professionals. When there is cardiac arrest and if nothing is done, after 10 minutes most people will be unrecoverable. If cardiac massage is performed and the use of the defibrillator is timely, it is possible to extend the 10-minute window and save many lives! Sadly, it is estimated that over 90% of victims of a cardiac arrest that occur outside of a hospital will die. For this reason, it is important to extend life support training and access to automated external defibrillators to as many people as possible, as every help counts! In the case of cardiac arrest survivors, it is mandatory to carry out an adequate and exhaustive clinical investigation to understand the cause and treat it appropriately. Myocardial infarction or heart attack What happens in a myocardial infarction? A myocardial infarction, also known as a heart attack, can be a sudden event with intense symptoms or be preceded by warning and progressive worsening symptoms ; In a myocardial infarction, heart cells suffer from ischemia and at that time the first symptoms appear! The most common symptoms are: Pain or discomfort in the chest, described as a feeling of pressure or tightness, which can radiate to other regions, such as the shoulders, arms, neck, among others; There may also be difficulty breathing, nausea, vomiting, sweating, dizziness, palpitations and eventually fainting. In many cases, the first manifestation of an acute myocardial infarction can be cardiac arrest , which occurs as a result of the sudden interruption of blood circulation and leads to ventricular fibrillation. It is estimated that in 50% of cases of myocardial infarction, cardiac arrest may be the first manifestation of the disease. It is for this reason that the two diseases are often confused . Why does a myocardial infarction happen? In a myocardial infarction, blood stops circulating in a certain area of the heart , irrigated by a coronary artery, or by a branch of it, which is partially or totally blocked by a clot . When an area of the heart muscle stops receiving blood, it is called ischemia. And if this ischemia persists , it can result in the death of myocardial cells. Blockage of the coronary arteries is most often due to atherosclerosis, that is to say, fat deposits that progressively grow on their walls. Under certain conditions and suddenly, these fat deposits can lead to the formation of clots and the consequent interruption of blood flow. What to do in the face of a myocardial infarction? Like cardiac arrest, acute myocardial infarction is also a medical emergency, and requires prompt intervention . For this reason, when there is chest pain or another symptom that is suspicious of a heart attack, help should be sought immediately, ideally by calling 112 . Meet the carrdiology clinical team from Hospital da Luz network The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
