Implantable cardioverter defibrillator
An implantable cardioverter defibrillator (ICD) is a battery-powered device that monitors electrical activity in the heart and when an arrhythmia is detected is able to deliver an electrical shock to terminate the abnormal rhythm. ICDs are used to prevent sudden cardiac death (SCD) in those that have survived a prior episode of sudden cardiac arrest (SCA) due to ventricular fibrillation or ventricular tachycardia (secondary prevention). ICDs are also used prophylactically to prevent sudden cardiac death in certain high risk patient populations (primary prevention).Numerous studies have been conducted on the use of ICDs for the secondary prevention of SCD. These studies have shown improved survival with ICDs compared to the use of anti-arrhythmic drugs. ICD therapy is associated with a 50% relative risk reduction in death caused by an arrhythmia and a 25% relative risk reduction in all cause mortality.Primary prevention of SCD with ICD therapy for high-risk patient populations has similarly shown improved survival rates in a number of large studies. The high-risk patient populations in these studies were defined as those with severe ischemic cardiomyopathy (determined by a reduced left ventricular ejection fraction (LVEF)). The LVEF criteria used in these trials ranged from less than or equal to 30% in MADIT-II to less than or equal to 40% in MUSTT. Management
Sudden cardiac arrest may be treated via attempts at resuscitation. This is usually carried out based upon basic life support, advanced cardiac life support (ACLS), pediatric advanced life support (PALS), or neonatal resuscitation program (NRP) guidelines.
: 833  Additionally, individuals with LQTS should avoid certain medications that carry the risk of increasing the severity of this conduction abnormality such as certain anti-arrhythmic, anti-depressant, and quinolone or macrolide antibiotics. Non-cardiac causes
Non-cardiac causes accounts for 15 to 25% of cardiac arrests. The most common non-cardiac causes are trauma, major bleeding (gastrointestinal bleeding, aortic rupture, or intracranial hemorrhage), hypovolemic shock, overdose, drowning, and pulmonary embolism. Cardiac arrest can also be caused by poisoning like the stings of certain jellyfish, or through electrocution, like lightning. Reversible causes
Other non-cardiac causes of cardiac arrest may result from temporary disturbances in the bodies homeostasis. This may be the result from changes in electrolyte ratios, oxygen saturation, or alterations of other ions influencing the bodys pH. Mnemonic for reversible causes
"Hs and Ts" is the name for a mnemonic used to remember the treatable or reversible causes of cardiac arrest. Note: This mnemonic includes causes of cardiac and non-cardiac origin, but all are reversible with appropriate and time-sensitive treatment.