Editing Cardiac tamponade (section)

== Diagnosis ==
[[File:Uotw78.webm|thumb|left|upright=1.3|An ultrasound of the heart showing cardiac tamponade.<ref name=UOTW78>{{cite web|last1=Smith|first1=Ben|title=UOTW#78 - Ultrasound of the Week|url=https://www.ultrasoundoftheweek.com/uotw-78/|website=Ultrasound of the Week|access-date=13 March 2017|date=27 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170313124516/https://www.ultrasoundoftheweek.com/uotw-78/|archive-date=13 March 2017}}</ref>]]

The three classic signs, known as [[Beck's triad (cardiology)|Beck's triad]], are [[Hypotension|low blood pressure]], jugular-venous distension, and muffled [[heart sounds]].<ref name="Dolan">{{cite book|title=Accident and emergency: theory into practice|vauthors=Holt L, Dolan B|publisher=Baillière Tindall|year=2000|isbn=978-0-7020-2239-5|location=London}}</ref> Other signs may include [[pulsus paradoxus]] (a drop of at least 10 mmHg in arterial blood pressure with inspiration),<ref name="Mattson" /> and [[ST segment]] changes on the [[electrocardiogram]],<ref name="Dolan" /> which may also show low voltage [[QRS complex]]es.<ref name="Longmore" />

===Medical imaging===
Tamponade can often be diagnosed radiographically. [[Echocardiography]], which is the diagnostic test of choice, often demonstrates an enlarged pericardium or collapsed ventricles. A large cardiac tamponade will show as an enlarged globular-shaped heart on chest x-ray. During inspiration, the negative pressure in the [[thoracic cavity]] will cause increased pressure into the right ventricle.  This increased pressure in the right ventricle will cause the interventricular septum to bulge towards the left ventricle, leading to decreased filling of the left ventricle. At the same time, right ventricle volume is markedly diminished and sometimes it can collapse.<ref name=Longmore/>

{{gallery
|width=220
|File:Uotw78b (convert-video-online.com).webm|Apical ultrasound image of the heart in a person with cardiac tamponade. Note how the right atrial collapses during systole.<ref name=UOTW78/>
|File:UltrasoundCardiacTamponade.webm|Ultrasound image of the [[inferior vena cava]] (IVC) in a person with cardiac tamponade. Note that the IVC is large and changes minimally with breathing.<ref name=UOTW78/>
}}

===Differential diagnosis===
Initial diagnosis of cardiac tamponade can be challenging, as there is a broad [[differential diagnosis]].<ref name=":0" /> The differential includes possible diagnoses based on symptoms, time course, mechanism of injury, patient history. Rapid onset cardiac tamponade may also appear similar to pleural effusions, [[obstructive shock]], shock, pulmonary embolism, and [[tension pneumothorax]].<ref name=Gwinnutt/><ref name=":0" />

If symptoms appeared more gradually, the differential diagnosis includes acute [[Heart failure with preserved ejection fraction|heart failure]].<ref>{{Citation|last1=Chahine|first1=Johnny|title=Left Ventricular Failure|date=2019|url=http://www.ncbi.nlm.nih.gov/books/NBK537098/|work=StatPearls|publisher=StatPearls Publishing|pmid=30725783|access-date=2019-08-02|last2=Alvey|first2=Heidi}}</ref>

In a person with trauma presenting with [[pulseless electrical activity]] in the absence of hypovolemia and tension pneumothorax, the most likely diagnosis is cardiac tamponade.<ref name="ACS">American College of Surgeons Committee on Trauma (2007). ''Advanced Trauma Life Support for Doctors, 7th Edition''. Chicago: American College of Surgeons</ref>

In addition to the diagnostic complications afforded by the wide-ranging differential diagnosis for chest pain, diagnosis can be additionally complicated by the fact that people will often be weak or faint at presentation. For instance, a fast rate of breathing and difficulty breathing on exertion that progresses to air hunger at rest can be a key diagnostic symptom, but it may not be possible to obtain such information from people who are unconscious or who have convulsions at presentation.<ref name=Spod2003 />