Cardiac Tamponade

Haemodynamic compromise from pericardial fluid (or blood, pus, gas, tumour) compressing the heart, so intrapericardial pressure exceeds cardiac filling pressures, diastolic filling falls and stroke volume drops. It is a clinical diagnosis and a medical emergency.

• Causes: malignancy, pericarditis (viral, tuberculous, bacterial, uraemic), iatrogenic perforation (percutaneous coronary intervention, ablation, pacemaker or defibrillator leads, central lines, cardiac surgery), penetrating or blunt trauma, aortic dissection, free wall rupture after infarction, anticoagulant related haemopericardium, and connective tissue disease.
• Mechanism: rising pericardial pressure equalises diastolic pressures, ventricles compete for volume (ventricular interdependence), and respiratory variation increases. Rapid accumulation of 100 to 200 mL can be enough.
• Variants: low pressure tamponade (volume depleted, with small rises in filling pressure), regional tamponade (clot compressing one chamber after cardiac surgery), and tamponade with pre-existing pulmonary hypertension or left ventricular hypertrophy in which classic echo signs are masked.
• With prompt drainage, survival from the acute event is about 85 to 90%; prognosis depends on the cause (poor in malignancy, haemopericardium from dissection and ventricular rupture).

• Dyspnoea, chest discomfort, anxiety, presyncope, collapse.
• Signs: tachycardia (usually greater than 100 beats/min), hypotension, raised jugular venous pressure with preserved x descent and absent y descent, muffled heart sounds (Beck triad of hypotension, raised jugular venous pressure and muffled heart sounds is present in only a minority), pulsus paradoxus (inspiratory fall in systolic pressure greater than 10 mmHg), tachypnoea with clear lungs, cool peripheries, oliguria. Kussmaul sign is usually absent.
• Differential diagnosis: tension pneumothorax, massive pulmonary embolism, right ventricular infarction, constrictive pericarditis, acute severe asthma or COPD (pulsus paradoxus), cardiogenic shock, hypovolaemic and septic shock.
• Complications: obstructive shock, cardiac arrest with pulseless electrical activity, acute kidney injury, hepatic congestion, and pericardial decompression syndrome (pulmonary oedema or right ventricular failure after drainage).

• Bedside echocardiography is the diagnostic test. Do not delay drainage for laboratory results. Findings: effusion with right atrial systolic collapse, right ventricular diastolic collapse, plethoric inferior vena cava (greater than 2.1 cm with less than 50% collapse), exaggerated respiratory variation of mitral (greater than 25%) and tricuspid (greater than 40%) inflow, swinging heart.
• ECG: tachycardia, low voltage, electrical alternans. Chest X-ray: enlarged globular cardiac silhouette (normal in acute small haemopericardium).
• CT when the patient is stable and the cause is unclear (aortic dissection, loculated clot, mass).
• After drainage: send fluid for haematocrit, cell count, protein, LDH, Gram stain, culture, acid fast tests and cytology; send full blood count, coagulation, urea, creatinine, troponin, thyroid stimulating hormone, HIV test.

• Immediate actions while preparing drainage:
  • Give oxygen, obtain IV access, and monitor ECG, blood pressure and oxygen saturation.
  • Give a 250 to 500 mL bolus of 0.9% saline if the patient is hypovolaemic or hypotensive (transiently raises filling pressure). Avoid large volumes in a patient already volume overloaded.
  • Avoid diuretics, nitrates, vasodilators and beta blockers, and avoid intubation and positive pressure ventilation where possible, because they reduce venous return and may precipitate arrest.
  • Vasopressors and inotropes only as a bridge: noradrenaline 0.05 to 0.5 micrograms/kg/min or dobutamine 2.5 to 10 micrograms/kg/min (evidence limited).
• Definitive drainage:
  • Urgent echo guided pericardiocentesis by subxiphoid or apical (or parasternal) approach with a 16 to 18 gauge needle and a 6 to 8 French pigtail catheter, aspirating until haemodynamics recover (often 100 to 500 mL; a small volume removal can restore pressure). Leave the catheter until drainage is less than 25 mL/24 hours.
  • Blind subxiphoid needle drainage only in peri arrest situations when echo guidance is unavailable.
  • Emergency surgical drainage (subxiphoid window or sternotomy) for traumatic tamponade, post-cardiac surgery tamponade, clotted haemopericardium, ventricular rupture, aortic dissection, and failed needle drainage; resuscitative thoracotomy in traumatic arrest.
  • In aortic dissection with tamponade, drain only the minimum to restore perfusion and proceed to surgery, since over drainage raises aortic pressure and promotes rupture.
• Reverse anticoagulation:
  • Heparin: protamine 1 mg per 100 units of heparin given in the previous 2 to 3 hours (maximum 50 mg).
  • Warfarin: vitamin K 5 to 10 mg IV with prothrombin complex concentrate 25 to 50 units/kg.
  • Direct oral anticoagulants: specific reversal agent or prothrombin complex concentrate 25 to 50 units/kg where available.
• After drainage:
  • Monitor continuously for 24 hours; repeat echocardiography at 24 hours.
  • Pericardial decompression syndrome (acute pulmonary oedema, hypotension, new right ventricular failure after drainage): furosemide 20 to 40 mg IV, noradrenaline or dobutamine as needed, and cautious fluid use.
  • Recurrence: pericardial window or balloon pericardiotomy.
  • Treat the cause: cancer directed therapy; anti-tuberculosis therapy with rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg (maximum 2 g) and ethambutol 15 mg/kg (maximum 1.2 g) daily for 2 months then rifampicin and isoniazid for 4 months; intensive dialysis for uraemia; ibuprofen 600 mg 8-hourly with colchicine 0.5 mg twice daily for viral pericarditis.
• Special groups:
  • Children: 10 to 20 mL/kg saline bolus; drain with age appropriate catheters under echo guidance.
  • Pregnancy: left lateral tilt, drain when haemodynamically significant, fetal monitoring when viable.
  • Renal failure: intensive dialysis with minimal heparin, with drainage for instability.
  • Anticoagulated and thrombocytopenic patients: correct coagulopathy but do not delay drainage in unstable patients.
• Red flags: hypotension, shock, cardiac arrest, altered mental state, oliguria.
• Follow up: echocardiography at 24 hours, 1 week and 1 month; remove the catheter when drainage is less than 25 mL/24 hours; review for constriction at 3 to 6 months.