Cardiac arrest is a sudden loss of blood flow resulting from the failure of the heart to effectively pump. Symptoms include loss of consciousness and abnormal or absent breathing. Some individuals may experience chest pain, shortness of breath, or nausea before cardiac arrest. If not treated within minutes, it usually leads to death.The most common cause of cardiac arrest is coronary artery disease. Less common causes include major blood loss, lack of oxygen, very low potassium, heart failure, and intense physical exercise. A number of inherited disorders may also increase the risk including long QT syndrome. The initial heart rhythm is most often ventricular fibrillation. The diagnosis is confirmed by finding no pulse. While a cardiac arrest may be caused by heart attack or heart failure, these are not the same.
Prevention includes not smoking, physical activity, and maintaining a healthy weight. Treatment for cardiac arrest include immediate cardiopulmonary resuscitation (CPR) and, if a shockable rhythm is present, defibrillation. Among those who survive, targeted temperature management may improve outcomes. An implantable cardiac defibrillator may be placed to reduce the chance of death from recurrence.
Cardiac arrest is preceded by no warning symptoms in approximately 50 percent of people. For those who do experience symptoms, they will be non-specific, such as new or worsening chest pain, fatigue, blackouts, dizziness, shortness of breath, weakness and vomiting. When cardiac arrest occurs, the most obvious sign of its occurrence will be the lack of a palpable pulse in the victim. Also, as a result of loss of cerebral perfusion (blood flow to the brain), the victim will rapidly lose consciousness and will stop breathing.
The main criterion for diagnosing a cardiac arrest, as opposed to respiratory arrest, which shares many of the same features, is lack of circulation; however, there are a number of ways of determining this. Near-death experiences are reported by 10 to –20 percent of people who survived cardiac arrest.