Cardiac arrest

Cardiac arrest is the cessation of purposeful blood pumping by the heart, which is invariably fatal if not reversed by cardio-pulmonary resuscitation (CPR), usually requiring [[Advanced Cardiac Life Support]. Electrical activity of the heart does not necessarily cease; it may simply not stimulate the cardiac musclature, as in electromechanical dissociation (EMD), or ineffectively stimulate it, as in ventricular fibrillation (VF). VF, indeed, is the most common rhythm seen in emergency medicine.

Basic CPR, with closed-chest compressions and possibly rescue breathing, rarely reverses adult arrest, but is a potentially life-saving intervention that buys time for more advanced interventions, such as electrical defibrillation to reverse VF. ACLS is most likely to be effective, although with a much lower success rate than popular perception, with metabolically related arrests. Arrests caused by trauma have a much more dismal prognosis, although heroic, highly-skilled interventions such as opening the chest and manually compressing the heart can work in some cases, usually with massive fluid replacement. Cardiac arrest caused by blunt chest trauma is considered irreversible by most trauma physicians.

Terminology in this area can be confusing. Heart failure does not mean the heart has literally stopped, but is a spectrum of degradations in pumping function. Terminal heart failure can lead to cardiac arrest. A subset of arrests are of the form of sudden cardiac death, which, despite the name, has one of the better chances of resuscitation; it is often due to VF.