Cardiovascular · Topic 26 of 48

Cardiac Tamponade

Cardiovascular · obstructive shock

Cardiac Tamponade

Pericardial pressure stops the heart filling: hypotension, distended neck veins, pulsus paradoxus over 10 mmHg — drain it now, unless dissection or rupture needs surgery.

Key numbers

Pulsus paradoxus over 10 mmHgpulsus > 10 mmHg

Small saline bolus as a bridge250–500 mL

01 · Look forBeck's triad: hypotension, muffled sounds, JVD

Beck's triad — hypotension, muffled heart sounds and distended neck veins — is classic but often incomplete (neck veins may be flat with hypovolemia); tachycardia and dyspnea are usual.

02 · Look forPulsus paradoxus over 10 mmHg

Pulsus paradoxus — an inspiratory fall in systolic BP of more than 10 mmHg — accompanies nearly all severe tamponade; it also occurs in COPD, asthma, pulmonary embolism and RV infarction.

03 · DoEmergency pericardiocentesis for unstable tamponade

Unstable tamponade needs immediate drainage, ideally echo-guided pericardiocentesis (subxiphoid, apical or parasternal approach); removing even a small volume can restore blood pressure.

Causes & risk factors

Why it happens

Speed of accumulation matters more than volumeAs little as 150 mL of rapidly accumulating blood can cause tamponade, whereas a slowly accumulating effusion may reach 1.5–2 L before cardiac output falls.

Causes: cancer, pericarditis, trauma, procedures, dissectionCauses include malignancy, pericarditis of any cause, uremia, penetrating chest trauma, iatrogenic perforation (catheterization, pacemaker or central line), post-MI free-wall rupture and aortic dissection; anticoagulation raises risk.

Presentation

What you'll see

Echo: effusion with right heart collapse must knowBedside echo supports tamponade: effusion with right atrial systolic and right ventricular diastolic collapse, a plethoric IVC (under 50% inspiratory collapse) and exaggerated respiratory variation of inflow; tamponade stays a clinical diagnosis.

Low voltage and electrical alternansThe ECG may show low QRS voltage and electrical alternans from the swinging heart, but neither is sensitive or specific for tamponade.

Equal diastolic pressures, absent y descentRight heart catheterization shows elevated, equal diastolic pressures (about 10–30 mmHg) in all chambers and the pulmonary artery, a preserved x descent and a lost y descent.

Do right now

In this order

First moves

Echo: effusion with right heart collapse

→

Small saline bolus as a bridge250–500 mL

→

Avoid intubation and positive pressure before drainage

→

Emergency pericardiocentesis for unstable tamponade

Why each step

Echo: effusion with right heart collapseBedside echo supports tamponade: effusion with right atrial systolic and right ventricular diastolic collapse, a plethoric IVC (under 50% inspiratory collapse) and exaggerated respiratory variation of inflow; tamponade stays a clinical diagnosis.

Small saline bolus as a bridgeWhile awaiting drainage, a small saline bolus (250–500 mL) can help hypotensive, hypovolemic patients; larger volumes can raise intrapericardial pressure, IV diuretics are contraindicated, and inotropes add little.

Avoid intubation and positive pressure before drainagePositive-pressure ventilation raises intrathoracic pressure and can cut cardiac output by up to 25% in tamponade, and induction can precipitate arrest; avoid both before drainage unless absolutely necessary.

Emergency pericardiocentesis for unstable tamponadeUnstable tamponade needs immediate drainage, ideally echo-guided pericardiocentesis (subxiphoid, apical or parasternal approach); removing even a small volume can restore blood pressure.

Management

Orders

Trauma tamponade: window or thoracotomyIn trauma, subxiphoid pericardiocentesis only temporizes and can be falsely negative because blood clots; definitive care is a pericardial window or thoracotomy/sternotomy.

Red flags & don'ts

Avoid harm

Dissection or free-wall rupture: surgery, not needle avoidTamponade from type A aortic dissection or post-MI free-wall rupture is surgical; needle pericardiocentesis is contraindicated because rapid decompression can worsen bleeding. If the patient cannot survive to surgery, drain only small amounts.

The rules

Know these

Echo collapse alone does not mandate drainageSignificant tamponade is a clinical diagnosis: chamber collapse on echo without clinical compromise is not by itself an indication for pericardiocentesis.

Tamponade or constrictive pericarditis?

Commonly confused

Pulsus paradoxus	Nearly always in severe tamponade (> 10 mmHg)
Kussmaul sign	Absent
Atrial pressure tracing	x descent kept, y descent lost
Heart sounds	Muffled

More detail

Reference

Show 5 reference facts

Loculated effusions or localized hematoma (for example after cardiac surgery) can compress selected chambers and cause regional tamponade without the classic physical or echo signs.

Under positive-pressure ventilation, pulsus paradoxus and respiratory inflow variation are blunted or absent and IVC plethora becomes nonspecific; chamber collapse may be intermittent.

Relative contraindications to nonemergent pericardiocentesis: uncorrected coagulopathy, anticoagulant therapy and platelets below 50,000/mm³; none are absolute when tamponade causes shock.

After drainage, aspirate the pericardial catheter every 4–6 hours and remove it once output is below 25–30 mL/24 h; obtain a chest radiograph to exclude pneumothorax.

Recurrent or persistent symptomatic effusions, often malignant, may need a balloon pericardiotomy or surgical pericardial window; send fluid for cytology and culture.

Pearl

Beck's triad is the textbook picture but is often incomplete — pulsus paradoxus and the bedside echo find the rest.

Sources · Merck Manual Professional — Pericarditis (pericardial effusion and cardiac tamponade) · Merck Manual Professional — Cardiac Tamponade (thoracic trauma) · ESC e-Journal of Cardiology Practice Vol 15 — Pericardiocentesis in cardiac tamponade: indications and practical aspects (2017) · ESC e-Journal of Cardiology Practice Vol 15 — Cardiac tamponade due to aortic dissection: clinical picture and treatment (2017) · Cardiac Tamponade Under Positive-Pressure Ventilation (review). Rev Cardiovasc Med 2026 — PMC13339243 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).