Cardiovascular

Cardiac Tamponade

Fluid, blood, pus or gas in the pericardial sac raises the pressure around the heart until the ventricles cannot fill, so cardiac output falls despite normal contractility.

In a nutshell

Cardiac tamponade is obstructive shock: pericardial fluid raises the pressure around the heart until the ventricles cannot fill. Suspect it from shock with a raised JVP, confirm with urgent bedside echocardiography and arrange immediate pericardiocentesis.

Classic presentation

A breathless, tachycardic patient two days after pacemaker insertion, now hypotensive with a raised JVP, quiet heart sounds and a systolic pressure that drops on inspiration.

Key points

There is no NICE guideline, Clinical Knowledge Summaries topic or Royal College of Emergency Medicine guidance on tamponade. The governing document is the 2025 European Society of Cardiology (ESC) guideline.
Pulsus paradoxus is an inspiratory fall in systolic pressure above 10 mmHg. That figure is the 2015 ESC guideline's stated convention, not a threshold the 2025 guideline sets.
Mitral inflow variation above 25% is the only echocardiographic percentage an ESC guideline publishes. Tricuspid percentages and inferior vena cava cut-offs are textbook convention.
The 2025 guideline calls an effusion above 20 mm at end-diastole large, and 10 to 20 mm moderate to large. Size grades risk, not tamponade.
No guideline states a fluid volume, a voltage definition of low voltage, or how long a drain stays in. Say the gap exists rather than quoting a number.
The 2025 guideline lists causes in order: malignancy, then iatrogenic or traumatic, then pericarditis, then tuberculosis. Iatrogenic tamponade after cardiac procedures is the one you will meet.
Electrical alternans happens because the heart swings in the fluid, changing its axis relative to the electrodes, so QRS amplitude alternates beat to beat.
Beck's triad is hypotension, a raised JVP and muffled heart sounds. It is late, often incomplete, and its absence never excludes tamponade.
Pericardiocentesis is for skilled physicians only. The 2014 ESC position statement asks for at least five procedures in a cardiology or emergency medicine curriculum.

First-line investigation

Urgent bedside transthoracic echocardiography, the guideline's first imaging technique (Class I, Level C). In peri-arrest, do not let it delay drainage.

Management

Recognise it and call

Treat suspected tamponade as obstructive shock. Call cardiology and critical care, alert cardiothoracic surgery, and get bedside echocardiography now.^1,3
Beck's triad is hypotension, a raised JVP and muffled heart sounds. Do not wait for all three: it is late and often incomplete.^2,3
Measure pulsus paradoxus: the gap between the pressure where Korotkoff sounds appear in expiration only and where they appear throughout the cycle.³

Confirm it on echocardiography

Look for early diastolic right ventricular collapse, late diastolic right atrial collapse, a swinging heart, a plethoric inferior vena cava and respiratory flow variation.^2,1
Mitral inflow variation above 25% is the only published guideline percentage. No ESC guideline gives a tricuspid figure or an inferior vena cava measurement.²
Effusion size grades risk, not tamponade: above 20 mm at end-diastole is large, and 10 to 20 mm moderate to large.¹

Hold the preload up, and do no harm

Cautious fluid boluses can bridge a hypotensive, hypovolaemic patient, reassessing after each. Give oxygen if hypoxaemic. Fluid must never delay drainage.^2,3
No guideline states a fluid volume. One UK trust protocol suggests 250 to 500 mL of 0.9% sodium chloride; larger volumes worsen the physiology.³
Vasodilators and diuretics are not recommended (Class III, Level C). Avoid positive-pressure ventilation where possible. Inotropes add little.^2,3

Drain it

Urgent pericardiocentesis or cardiac surgery is recommended (Class I, Level C). Echocardiographic guidance is mandatory and the approach is usually subxiphoid or apical.^2,5
Unstable or peri-arrest: drain without delay. Stable: the 2014 ESC position statement asks for drainage within 12 to 24 hours of diagnosis.⁵
Do not evacuate more than 1 L rapidly. Pericardial decompression syndrome causes pulmonary oedema and shock hours to days afterwards.^5,3

Surgery, trauma and arrest

Straight to theatre: type A aortic dissection, post-infarction free-wall rupture, severe chest trauma, uncontrollable iatrogenic bleeding, purulent effusion with sepsis, loculated effusions.^5,2
Contraindications to needle drainage: uncorrected coagulopathy, INR above 1.5, platelets below 50,000 per cubic millimetre, and small, posterior or loculated effusions.⁵
In traumatic cardiac arrest, treat reversible causes before chest compressions. Resuscitative thoracotomy needs expertise, equipment, environment and under 15 minutes elapsed.^6,7

Cause and sequel

Send fluid for cell count, biochemistry, microbiology including tuberculosis, and cytology, then treat the cause and make a plan for recurrence.^1,3
Leave the catheter in, aspirating every four to six hours, until the daily return falls below about 25 to 30 mL.⁵
Repeat echocardiography for reaccumulation and for effusive-constrictive physiology, where constriction is only uncovered once the fluid has gone.¹

Exam traps

A normal chest radiograph does not exclude tamponade. An effusion needs roughly 250 mL before it shows, and acute tamponade needs far less than that.
Blood pressure can be normal, or even high, in a previously hypertensive patient. Do not wait for hypotension before acting.
Diuretics and vasodilators are the classic wrong answer: they drop the filling pressure the patient is surviving on. Class III, Level C.
Positive-pressure ventilation can arrest a tamponading patient. Intubation is a critical care decision, not a reflex.
Type A aortic dissection and post-infarction free-wall rupture go to theatre. Decompressing with a needle can worsen the tear or the rupture.
Size does not make tamponade. A small rapid bleed after a cardiac procedure can kill while a large chronic effusion is walking about.
The triage points score is expert consensus, not a validated rule. Both the 2015 and 2025 guidelines say so in print.
Pulsus paradoxus is cardinal in tamponade, but the national asthma guideline (SIGN 158) says it should not be used to grade acute asthma severity.

Illustrations

Globular cardiac silhouette in tamponadeFrontal chest radiograph showing a smooth enlarged cardiac silhouette from a large effusion, with a caption warning that acute tamponade can have a normal-sized silhouette.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.