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"Syncope" is a medical term used to refer to complete loss of consciousness that is sudden and that might not present with obvious signs and symptoms that serve as a warning to seek immediate medical attention. Most people simply call syncope fainting. "Cardiac" refers to the heart muscle, so cardiac syncope is a sudden loss of consciousness that is brought on by an insufficient supply of oxygenated blood circulating in the blood vessels of the brain. The heart pumps blood throughout the entire body, and if it fails in its function, blood will not be supplied to all tissues in adequate amounts, including the brain. A number of medical problems and conditions can cause syncope, but when syncope is linked directly to a problem with the heart, it is cardiac syncope.
There are many disorders of the heart that can lead to inadequate pumping action or to the complete cessation of normal heartbeats, which in turn can result in cardiac syncope. Problems can occur with the electrical activity of the heart and with the mechanical pumping action of the muscle itself. Unlike other forms of syncope or fainting, losing consciousness because of a heart problem can and often does result in cardiac arrest, followed by respiratory arrest. This is clinical death, after which biological death will quickly occur if the patient is not resuscitated. Someone suffering cardiac syncope is unresponsive and might not have a pulse, depending on the exact condition or disorder that caused the incident.
Obstructive cardiac lesions and arrhythmias are the types of health problems that put an individual at risk for suffering cardiac syncope. It is obvious that any kind of obstruction can partially or completely interfere with oxygenated blood reaching the brain. The term "arrhythmias" refers to a group of various types of abnormal heart rhythms. Some of them are cause for immediate and great concern, among which is ventricular tachycardia, also known as V-tach. Other arrhythmias that lead to cardiac syncope are ventricular fibrillation (VF) and asystole.
Aortic stenosis and a myocardial infarction, commonly known as a heart attack, are among the mechanical causes of the left ventricle of the heart failing to perform adequately, leading to an interruption of blood flow to the brain. There are various medical interventions that can be taken to avoid cardiac syncope and to attempt to save the patient's life after it has occurred. For example, automated external defibrillators (AEDs) were designed and developed to analyze various arrhythmias such as VF, V-tach, pulseless electrical activity (PEA) and asystole. The AED, after analysis, will shock or advise the delivery of a shock if the arrhythmia is shockable. Cardiac syncope brought on by asystole and PEA, however, are not shockable.