What are the symptoms of cardiac tamponade?

Symptoms of Cardiac Tamponade

Cardiac tamponade presents with a constellation of symptoms including tachycardia, hypotension, pulsus paradoxus, raised jugular venous pressure, muffled heart sounds, decreased electrocardiographic voltage with electrical alternans, and an enlarged cardiac silhouette on chest X-ray. 1

Clinical Presentation

Cardinal Signs and Symptoms

• Tachycardia - compensatory mechanism to maintain cardiac output 1
• Hypotension - results from decreased cardiac output due to impaired ventricular filling 1
• Pulsus paradoxus - a key diagnostic finding defined as an inspiratory decrease in systolic arterial pressure of >10 mmHg during normal breathing 1, 2
• Raised jugular venous pressure - due to impaired right heart filling 1
• Muffled heart sounds - caused by fluid dampening cardiac sounds 1
• Dyspnea - can progress to orthopnea without rales on lung auscultation 3
• Weakness and fatigue - from reduced cardiac output 3
• Oliguria - secondary to decreased renal perfusion 3

Electrocardiographic Findings

• Decreased QRS voltage - due to dampening effect of pericardial fluid 1
• Electrical alternans - alternating QRS amplitude caused by swinging heart motion 1

Imaging Findings

• Enlarged cardiac silhouette on chest X-ray - particularly with slow-accumulating effusions 1

Pathophysiological Mechanism

Hemodynamic Changes

• Cardiac tamponade occurs due to compression of the heart from accumulation of fluid, blood, pus, clots, or gas in the pericardial space 1
• The stiffness of the pericardium creates a characteristic pressure-volume curve with initial slow ascent followed by a steep rise 1
• This makes tamponade a "last-drop" phenomenon where the final increment of fluid produces critical cardiac compression 1, 2

Mechanism of Pulsus Paradoxus

• During tamponade, the heart chambers become fixed in volume and compete for space 2
• Inspiration increases venous return to the right heart, causing the right ventricle to expand 2
• This creates a rightward septal shift that reduces left ventricular filling 2
• The result is decreased left ventricular stroke volume and systolic blood pressure during inspiration 2
• Pulsus paradoxus can be measured using sphygmomanometry by noting the difference between when Korotkoff sounds first appear during expiration versus throughout the respiratory cycle 2

Echocardiographic Signs

Key Findings

• Swinging heart motion - visible oscillation of the heart within the pericardial fluid 1
• Early diastolic collapse of the right ventricle - a specific sign of tamponade 1
• Late diastolic collapse of the right atrium - a sensitive but less specific sign 1
• Abnormal ventricular septal motion - due to ventricular interdependence 1
• Exaggerated respiratory variability (>25%) in mitral inflow velocity 1, 2
• Inspiratory decrease and expiratory increase in pulmonary vein diastolic forward flow 1
• Respiratory variation in ventricular chamber size 1, 2
• Inferior vena cava plethora without respiratory variation 1

Clinical Pitfalls and Caveats

• The magnitude of clinical and hemodynamic abnormalities depends on the rate of fluid accumulation, amount of pericardial contents, distensibility of the pericardium, and filling pressures of cardiac chambers 1
• Rapid accumulation of even small amounts of fluid can cause severe tamponade, while slow accumulation may allow compensation despite large volumes 1, 4
• Tamponade can be precipitated in patients with existing pericardial effusion by dehydration or exposure to vasodilators or intravenous diuretics 3
• In patients who have undergone cardiac surgery or have central venous catheters, tamponade should be suspected with unexplained hemodynamic deterioration 5
• Patients with liver disease and tense ascites may present with tamponade physiology due to extrinsic compression, mimicking classic tamponade symptoms 6

Diagnostic Approach

• Cardiac tamponade is primarily a clinical diagnosis that should be confirmed with echocardiography 1, 3
• Echocardiography is the single most useful diagnostic tool to identify pericardial effusion and assess its hemodynamic impact 1
• A structured echocardiographic approach should assess: quantity and quality of pericardial fluid, collapse of cardiac chambers, respiratory variation of ventricular diameters, inferior vena cava collapsibility, and flow patterns in atrioventricular valves 4
• Immediate echocardiographic evaluation and consideration of pericardiocentesis is required for unstable patients with suspected tamponade 2, 7