Cardiac Tamponade
Cardiology
Illness script · Cardiology
Cardiac Tamponade
Life-threatening compression of the heart by pericardial fluid accumulation, impairing diastolic filling and causing obstructive shock.
This illness script for Cardiac Tamponade covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.
01
Predisposing factors
- Malignancy (most common cause of large effusions — lung, breast, lymphoma)
- Viral/idiopathic pericarditis
- Post-MI free wall rupture (Dressler syndrome)
- Uremia (pericardial effusion in ESRD)
- Penetrating chest trauma, aortic dissection type A
- Iatrogenic: post-cardiac catheterization, pacemaker lead perforation
02
Presentation
- Classic Beck's Triad: hypotension + JVD + muffled heart sounds
- Pulsus paradoxus >10 mmHg drop in SBP with inspiration (pathognomonic)
- Tachycardia is universal and early; narrow pulse pressure
- Dyspnea, tachypnea, orthopnea without crackles
- Equalization of diastolic pressures on right heart catheterization
- Kussmaul sign is ABSENT (distinguishes from constrictive pericarditis)
03
Pathophysiology
- Fluid accumulates in pericardial sac → intrapericardial pressure rises
- Elevated pressure exceeds RV then LV diastolic pressure → impaired filling
- Reduced stroke volume → compensatory tachycardia → obstructive shock
- Rate of accumulation matters more than volume: acute 150–200 mL can be fatal
04
Diagnostics
- Echocardiography: first-line and gold standard — shows effusion + RV diastolic collapse
- ECG: sinus tachycardia, low-voltage QRS, electrical alternans (classic but late finding)
- CXR: enlarged 'water-bottle' cardiac silhouette (only if >250 mL accumulates slowly)
- Right heart cath: equalization of diastolic pressures (RA = RV diastolic = PCWP)
- Pearl: electrical alternans + tachycardia on ECG → high suspicion, get echo immediately
05
Management
- Immediate pericardiocentesis: definitive and life-saving (subxiphoid approach, echo-guided)
- IV fluid bolus as temporizing bridge to increase preload while preparing for drainage
- Avoid vasodilators, diuretics, and negative inotropes — all worsen hemodynamics
- Avoid positive-pressure ventilation if possible — reduces venous return and precipitates arrest
- Surgical pericardiotomy for traumatic/recurrent/purulent tamponade or failed pericardiocentesis
06
Clinical pivots
How to separate this script from the look-alikes that show up on exams and on the wards.
Tension Pneumothorax
Tension PTX shows tracheal deviation, absent breath sounds, and no pericardial effusion on echo; JVD and hypotension overlap but lung exam differs.
Constrictive Pericarditis
Constrictive pericarditis shows Kussmaul sign (absent in tamponade) and pericardial knock; no acute fluid on echo.
Distributive (Septic) Shock
Septic shock has warm extremities, wide pulse pressure, and no pulsus paradoxus or pericardial effusion.
Right Ventricular Myocardial Infarction
RV MI shows ST elevation in V1/right-sided leads and responds to fluids without pericardial effusion on echo.
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Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.