Winter is the high season for various cardiovascular diseases, and sudden cardiac death makes people talk about it because of its sudden and unpredictable onset. Is sudden cardiac death preventable and treatable? How should we avoid and prevent this disease in our daily life? I. Definition of sudden cardiac death Sudden cardiac arrest (SCA) refers to the sudden stopping of the heart, resulting in the interruption of blood supply to the brain and other important organs, which can lead to death if not treated in time. Mechanisms of sudden cardiac death Ventricular fibrillation is an arrhythmia, essentially a dysfunction of the electrical conduction system of the heart, which can lead to death within minutes and is the most common cause of SCAs. In ventricular fibrillation, the ventricles fibrillate at a very fast rate, failing to contract properly, and the pumping function of the heart is lost, interrupting the blood supply to all parts of the body and eventually leading to death. Other disorders of the electrical conduction system can also cause SCA, for example, various causes that cause the heart’s electrical signals to become very slow or even stop. If the heart has an electrical signal, but the heart muscle cannot respond to the signal, it will also lead to SCA. Causes of sudden cardiac death There are many diseases that can disrupt the electrical conduction system of the heart and lead to sudden cardiac death, such as coronary heart disease, structural heart disease, stress, etc. 1, coronary heart disease Coronary artery disease is referred to as coronary heart disease. The coronary arteries are responsible for providing adequate blood flow and oxygen to the heart muscle. And abnormal lipid metabolism will make the lipid in the blood deposited on the original smooth arterial lining, lipid material accumulation to form atherosclerosis-like white plaque, so coronary heart disease is also known as coronary atherosclerotic heart disease. The gradual increase of these plaques causes narrowing of the arterial lumen, blocking or interrupting blood flow, leading to myocardial ischemia and hypoxia, resulting in angina pectoris and, in severe cases, even myocardial infarction. Once myocardial infarction occurs, some of the myocardial cells become necrotic and are replaced by scar tissue, which disrupts the original electrical signaling system of the heart, with abnormal electrical signal conduction and increased incidence of lethal arrhythmias and sudden cardiac death. Coronary heart disease is the most important cause of sudden cardiac death in adults, but many people do not have symptoms and history of coronary heart disease before sudden cardiac death occurs. 2, abnormal working state of the body Changes in certain functional states of the human body can also lead to disorders in the working of the electrical signal system of the heart. For example: (1) strenuous physical activity. Strenuous physical activity can release large amounts of adrenaline. This hormone can trigger sudden cardiac death in people who already have heart disease. (2) Too low levels of potassium or magnesium in the blood. Potassium and magnesium play an important role in the electrical signaling system of the heart. (3) A large loss of blood. (4) the body is seriously lack of oxygen. 3, hereditary diseases Some families are particularly prone to sudden cardiac death cases, which may be related to genetics, that is, parents inherit abnormal genes to their offspring, some of the genes that determine the heart ion channel switch abnormalities, resulting in its regulation of the ion channel protein abnormalities, is a common feature of such diseases. Examples include longQTsyndrome (LQTS) and Brugada syndrome, which can cause sudden, uncontrollable and dangerous changes in heart rhythm. Other hereditary cardiovascular diseases that can lead to sudden cardiac death include hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy, left ventricular densification insufficiency, arrhythmogenic right ventricular dysplasia, etc. 4. Structural heart diseases Changes in the size or structure of the heart can also affect the electrical signal system of the heart. For example, the enlarged heart caused by long-term hypertension or myocarditis. The risk of sudden cardiac death increases significantly with age. SCA is three times more likely to occur in men than in women, and is more likely to occur in people with underlying heart disease. Other risk factors include: (1) history of coronary heart disease; (2) sudden death in the family; (3) history of arrhythmia; (4) heart failure (5) drug abuse, drug and alcohol abuse. The first symptom of sudden cardiac death is usually loss of consciousness (syncope) with no heartbeat (or pulse). Before SCA occurs, some people may feel an extremely fast heartbeat or vague dizziness, while others may have chest pain, shortness of breath, nausea, or vomiting. VI. Diagnosis of sudden cardiac death Sudden cardiac death usually occurs without warning, is very sudden and requires emergency treatment, so SCA is more of an afterthought. If you are at high risk for SCA, you should seek the help of a cardiologist. A cardiologist will work with you to determine if you need to take steps to prevent sudden cardiac death. Your doctor will usually recommend that you have the following tests: (1) An electrocardiogram. This is a simple, quick, and painless test to detect and record the electrical activity of the heart. It can clarify the frequency of the heart’s current contractions, the rhythm of the heartbeat (steady or irregular), the presence of myocardial ischemia or myocardial damage, and of course, in the eyes of an experienced doctor, some spider traces of hereditary cardiovascular disease, which can often be detected by the initial screening of an EKG. (2) Cardiac ultrasound. Ultrasound of the heart shows the structure and size of the heart and helps to understand the working status of the various chambers (chambers) and valves (valves) of the heart. (3) Cardiac nuclear scan and magnetic resonance imaging (MRI). A cardiac nuclear scan involves injecting a small amount of radioactive material into a vein that travels with the bloodstream to the heart, and then using a special machine to examine the area of distribution of the radioactive material to see how the heart is working. Cardiac MRI is a relatively new testing technique that provides a comprehensive analysis of the structure and function of the heart and is the most desirable and valuable diagnostic technique available. (4) Cardiac catheterization. This is a minimally invasive test that is performed in a special operating room. A catheter is inserted into a blood vessel in the upper arm or thigh, and the catheter enters the heart chambers or coronary arteries, where the doctor injects some “contrast” through the catheter. Under X-ray light and a television screen, the doctor can look into the heart chambers, valves or coronary arteries to diagnose any heart disease. (5) Electrophysiological examination. This is also a minimally invasive test in which the doctor uses a special catheter to record the electrical activity of the heart to figure out the type of arrhythmia, the point of origin of the arrhythmia and the specific pathogenesis. Once these problems are determined, targeted treatment can be administered. (6) Hematological tests. Your doctor may suggest you to check the level of potassium and magnesium in your blood; if someone in your family has sudden death, your doctor may further suggest you to test some indicators related to genetics. Treatment of sudden cardiac death (1) Out-of-hospital emergency. patients with SCA usually require immediate electrical resuscitation, a device that delivers electrical current to the heart to help restore the heart to a normal rhythm. performing electrical resuscitation within minutes of the onset of SCA can significantly improve the patient’s survival rate, and as time passes, the patient’s chances of survival decline rapidly. If someone has an SCA, the sooner those around him or her call for help and the sooner life-saving treatment begins, the hope of survival is greatly increased. (2) In-hospital treatment. If a patient survives sudden cardiac death, he or she should be taken to a hospital for further treatment. The doctor will look for the cause of the sudden cardiac death and if coronary artery disease is considered, the patient will be advised to undergo further cardiac catheterization to identify the coronary artery lesion and depending on the severity of the coronary artery lesion, either a stent will be placed to restore blood flow or the patient will be referred to cardiothoracic surgery for coronary artery bypass surgery. Often survivors of sudden cardiac death are treated with an ICD (implantable cardioverter-defibrillator), a small pacemaker-like device that is placed under the skin of the patient’s chest through a minor procedure. This small device determines the electrical activity of the heart and delivers electrical impulses when needed to help control the dangerous electrical activity of the heart. Prevention of sudden cardiac death 1. Patients who have had sudden cardiac death but survived are at high risk of having another SCA, and studies have shown that ICD therapy reduces the probability that a patient will die from a second SCA event. 2.Have not had sudden cardiac death but have high risk factors If you have severe coronary artery disease, then the risk of SCA is increased. Doctors usually prescribe beta-blockers to reduce the occurrence of SCA. Of course all treatments that restore coronary blood flow can reduce the occurrence of SCA, such as intracoronary artery stenting or coronary artery bypass surgery. ICD implantation is also a very important treatment measure. 3. No history of sudden cardiac death and no known risk factors A healthy lifestyle will help us reduce the risk of developing sudden cardiac death, coronary artery disease or other heart diseases. This includes a healthy diet, moderate physical activity, quitting smoking, weight loss, etc.