Cardiac tamponade

Learning objectives

Cardiac tamponade is characterized by compression of the heart chambers caused by an accumulation of fluid in the pericardial space
Common causes:
- Pericarditis
- Tuberculosis
- Trauma
- Malignancy
- Iatrogenic, e.g., after cardiac surgery and invasive procedures
Intrapericardial pressure increases, causing an increase in right (RV) and left ventricular (LV) filling pressures
Increased intrapericardial pressure eventually compresses all the cardiac chambers causing a decrease in cardiac output
Tamponade leads to an exaggerated shift of the interventricular septum to the left during inspiration resulting in impairment of LV filling
Decrease in systemic arterial pressure of >10 mmHg during inspiration (pulsus paradoxus)
Crucial factors in the development of tamponade:
- Rate of fluid accumulation relative to pericardial stretch
- Presence or absence of compensatory mechanisms
Gradually developing effusions are largely asymptomatic, rapidly accumulating effusions can present with tamponade

Symptoms:
- Dyspnea (usually the first and most sensitive)
- Orthopnea
- Chest discomfort
Clinical manifestations are consistent with low cardiac output and high central venous pressure:
- Low mean arterial pressure
- Cool peripheries
- Signs of poor end-organ perfusion (e.g., low urine output)
Palpating the pulse reveals an apparent variation in pulse volume due to pulsus paradoxus
Jugular venous pressure is typically increased, with distended neck veins apparent
Sympathetic tone is increased and manifests as tachycardia, diaphoresis, anxiety and poor distal perfusion
A pericardial rub might be heard on auscultation in patients with inflammatory pericardial disease

Chest X-ray: Enlarged globular cardiac silhouette in chronic large pericardial effusions
ECG:
- QRS complexes may be lower
- Sinus tachycardia is common
- Atrial dysrhythmias may be present
- Beat-to-beat variation in both amplitude and axis of the QRS complexes may be present in patients with large effusions
Transthoracic (TTE) or transesophageal echocardiography (TEE): determine the size, location, and hemodynamic effects of the pericardial effusion:
- Effusions up to 10 mm in thickness during diastole are considered small, between 10 and 20 mm moderate, and greater than 20 mm large
- Collapse of the cardiac chambers
- Inferior vena cava dilatation
- Increased respiratory variation in the intracardiac blood flow measured with Doppler
- Excessive leftward shift of the interventricular septum during spontaneous inspiration
Differential diagnoses:
- Epicardial fat
- Pleural effusions

Cardiac tamponade is an emergency requiring relief of the pressure effect of the pericardial fluid
This is achieved by drainage procedures, which can be percutaneous or open surgical techniques