Editing Cardiac arrest (section)

==Signs and symptoms==
Cardiac arrest is not preceded by any warning symptoms in approximately 50 percent of people.<ref name="Lilly-2015">{{cite book|title=Braunwald's heart disease: a textbook of cardiovascular medicine | publisher=Saunders| vauthors = Lilly LS, Braunwald E, Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E |year=2015 |isbn=9781455751341 | veditors = Myerburg RJ |edition=Tenth|location=Philadelphia, PA|pages=821–860|chapter=Cardiac Arrest and Sudden Cardiac Death|oclc=890409638}}</ref> For individuals who do experience symptoms, the symptoms are usually nonspecific to the cardiac arrest.<ref name="National Heart, Lung and Blood Institute-2011">{{cite web |date=1 April 2011 |title=What Are the Signs and Symptoms of Sudden Cardiac Arrest? |url=https://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs |url-status=live |archive-url=https://web.archive.org/web/20150621171145/https://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs |archive-date=21 June 2015 |access-date=2015-06-21 |publisher=National Heart, Lung and Blood Institute}}</ref> For example, new or worsening [[chest pain]], [[fatigue (medical)|fatigue]], [[syncope (medicine)|blackout]]s, [[dizziness]], [[shortness of breath]], [[weakness]], or [[vomiting]].<ref name="National Heart, Lung and Blood Institute-2011" /><ref name="NIH2022Def" />

When cardiac arrest is suspected by a layperson (due to signs of unconsciousness, abnormal breathing or no pulse) it should be assumed that the victim is in cardiac arrest. Bystanders should call [[emergency medical services]] (such as 911, 999 or 112) and initiate [[Cardiopulmonary resuscitation|CPR]].