الفهرس 
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Abstract
Sudden cardiac death (SCD) is defined as unexpected, non-traumatic death occurring within one hour of the onset of new or worsening symptoms (witnessed arrest) or, if unwitnessed, within 24 hours of last being seen alive. SCD may be preceded by symptoms such as chest pain, dyspnea, palpitations, presyncope, and syncope but many individuals have no symptoms prior to the event.
The most common electrophysiologic mechanisms leading to SCD are tachyarrhythmias such as ventricular fibrillation (VF) or ventricular tachycardia (VT). Interruption of tachyarrhythmias, using either an automatic external defibrillator (AED) or an implantable cardioverter defibrillator (ICD), has been shown to be an effective treatment for VF and VT. Most cases of SCD occur in patients with structural abnormalities of the heart. Myocardial infarction (MI) and post-MI remodeling of the heart is the most common structural abnormality in patients with SCD. Less commonly, SCD happens in patients who may not have apparent structural heart disease.
a) SCD in Athletes
The definition of SCD in athletes also varies; some estimates of incidence include only deaths with exertion or shortly (< 1 hour) after exertion, while others include any SCD in an athlete (exertional or outside of exertion). An increased risk has been found with male gender, black race, and basketball participation.
In the majority of U.S. studies, the most commonly identified cause for SCD in young athletes is HCM, The prevalence of HCM in the general population is up to 1 in 200 individuals, and in many the first presenting symptom may be SCD.
Congenital coronary artery anomalies, consisting of a variety of abnormalities of coronary origin and proximal course, are the second most common cause of SCD in young U.S. athletes, responsible for around 17% of SCD cases. .
The most common identified cause of SCD in the older athletes population is atherosclerotic CAD. Although regular physical activity clearly reduces the risk of acquiring CAD. There remains debate as to whether the predominant mechanism for SCD is plaque rupture or supply/demand mismatch during exercise.
Athletes evaluation is extending beyond a history, physical exam, and ECG is indicated if any of these preparticipation tests are abnormal and/or an athlete presents with symptoms during the course of practice or competition.
b) Sudden Infant Death Syndrome (SIDS).
SIDS is defined as the sudden, unexpected death of an infant less than 1 year of age that cannot be explained despite investigation, including a complete autopsy, examination of the death scene, and review of the clinical and social history.
SIDS has many cardiac causes as myocarditis, Congenital heart disease, Congenital aortic valvular stenosis, Anomalous origin of the left coronary artery and Congenital heart block.
Non cardiac risk factors of SIDS include: smoking during pregnancy, putting infants to bed on their stomachs, Apnea, very low birth weight, Black race, Alcohol and Multiple births.
Management of sudden cardiac arrest
The diagnosis of sudden cardiac arrest is a definitive one. The patient is unresponsive, and assessment of airway, breathing, and circulation shows absence of normal breathing and no signs of circulation. Assessment of the specific cardiac rhythm disturbance responsible should be immediate, whether by automated external defibrillator or other cardiac monitoring is essential for management. Possibilities include ventricular fibrillation, pulseless ventricular tachycardia, asystole and pulseless electrical activity.
Heart rhythms associated with cardiac arrest are divided into two groups: shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT)) and non-shockable rhythms (asystole and pulseless electrical activity (PEA)). The main difference in the treatment of these two groups is the need for attempted defibrillation in patients with VF/pVT. Other actions, including chest compression, airway management and ventilation, vascular access, administration of adrenaline, and the identification and correction of reversible factors, are common to both groups. The ALS algorithm provides a standardised approach to the management of adult patients in cardiac arrest. Drugs and advanced airways are still included among ALS interventions, but are of secondary importance to early defibrillation and high quality and uninterrupted chest compressions.