Haemopericardium

Haemopericardium is blood in the pericardial sac. When it accumulates faster than the pericardium can stretch it causes cardiac tamponade, which is obstructive shock.

Epidemiology. Traumatic causes dominate in young adults. In older adults, causes are iatrogenic injury, anticoagulation, aortic dissection and myocardial rupture.

Causes and associations.

• Trauma: penetrating chest wounds and blunt cardiac rupture.
• Iatrogenic: percutaneous coronary intervention, pacemaker or defibrillator lead insertion, catheter ablation, valve procedures, central venous catheter and cardiac surgery.
• Type A aortic dissection with rupture into the pericardium, free wall rupture after myocardial infarction.
• Anticoagulation, thrombolysis, uraemia, malignancy and tuberculosis.

Pathophysiology. The pericardium is stiff, so as little as 100 to 200 mL of blood acutely can raise intrapericardial pressure over right atrial pressure, which limits diastolic filling, lowers stroke volume and causes shock. Chronic effusions of over 1 litre may be tolerated.

Presentation is dyspnoea, chest pain, tachycardia, hypotension, raised jugular venous pressure, muffled heart sounds (Beck triad) and pulsus paradoxus (inspiratory fall in systolic pressure over 10 mmHg). Cardiac arrest with pulseless electrical activity can occur. In hypovolaemia the venous pressure may be normal.

Red flags.

• Hypotension with chest trauma or after a cardiac procedure.
• Tearing chest or back pain with a pericardial effusion (aortic dissection).
• Pulseless electrical activity with low voltage ECG.

Point-of-care or formal echocardiography shows the effusion with right atrial or ventricular diastolic collapse, plethoric inferior vena cava and respiratory variation in mitral and tricuspid inflow. ECG may show low voltage or electrical alternans. Chest radiograph may show an enlarged globular heart. CT is used when stable and aortic dissection is possible. Check full blood count, coagulation tests, group and crossmatch.

Differential diagnosis. Tension pneumothorax, massive pulmonary embolism, haemorrhagic shock, constrictive pericarditis and acute myocardial infarction.

Resuscitation while preparing drainage. Give 500 mL crystalloid or blood to raise preload, maintain heart rate, and use noradrenaline 0.05 to 0.5 microgram/kg/min if hypotensive. Avoid diuretics, vasodilators and positive pressure ventilation where possible, since a rise in intrathoracic pressure can cause arrest.

Drainage.

• Pericardiocentesis directed by ultrasound (subxiphoid or apical, with the shortest path), with an 18 gauge needle then a catheter left in place for continuous drainage. Removal of 50 to 100 mL can restore haemodynamics.
• Surgical drainage (subxiphoid window, thoracotomy or sternotomy) for trauma, clotted blood, recurrent tamponade and ongoing bleeding. Emergency resuscitative thoracotomy for arrest after penetrating injury.
• Aortic dissection with tamponade: treat with urgent surgery. If drainage is needed to stabilise, remove only the smallest volume that maintains systolic pressure of about 90 mmHg.

Reverse coagulopathy.

• Heparin: protamine 1 mg for each 100 units of heparin given in the last 2 to 3 hours (maximum 50 mg as a single dose), infused slowly.
• Warfarin: prothrombin complex concentrate 25 to 50 units/kg and vitamin K 5 to 10 mg IV.
• Direct oral anticoagulant: idarucizumab 5 g IV for dabigatran, or prothrombin complex concentrate 50 units/kg (maximum 5000 units) for factor Xa inhibitors, or the specific reversal agent where available.
• Transfuse red cells for blood loss. Correct platelets and fibrinogen.

After drainage. Leave the catheter in until output is under 25 mL in 24 hours, with echocardiography before removal. Tranexamic acid 1 g IV over 10 minutes in trauma.

Monitoring. Continuous arterial pressure, ECG, drain output, haemoglobin every 4 to 6 hours and repeat echocardiography at 6 and 24 hours.

Referral and escalation. Cardiology, cardiothoracic surgery and intensive care at once.

Special groups. In uraemia, dialyse after drainage. In malignancy, discuss pericardial window and systemic therapy.