Cardiac Tamponade occurs when the pericardial pressure exceeds the pressure of the right atrium or right ventricle leading to decreased preload of the left ventricle and eventually a drop in cardiac output/blood pressure. It is considered an obstructive type of shock.
Recall that cardiac tamponade is more dependent on the rate of pericardial fluid accumulation versus the actual size.
On physical exam you may see Beck’s Triad defined as hypotension, jugular venous distension, and muffled heart sounds. You can also detect pulsus paradoxus as well. However, other diagnoses can cause false positives for these findings including severe COPD, tension pneumothorax, or other causes of obstructive shock.
Point of Care Ultrasound can offer a more definitive diagnoses of pericardial effusion and cardiac tamponade.
Ultrasound Findings of Cardiac Tamponade:
Using transthoracic echocardiography (TTE) you can see if the pericardial pressure exceed the right atrial or right ventricular pressures.
Since the lowest pressures in the heart is the right atrium, the first echo sign you will see of cardiac tamponade is right atrial systolic collapse.
The second echo sign you will see in cardiac tamponade is right ventricular diastolic collapse.
Either of these signs are considered positive echocardiographic signs of cardiac tamponade.
Note: Keep in mind that there is a difference between echocardiographic and clinical cardiac tamponade. Echocardiographic cardiac tamponade just exams to see if the right heart (RA or RV) are affected, the echo can’t tell if your patient is actually hypotensive. Clinical cardiac tamponade requires the patient to be hypotensive and in shock. Even though the echocardiographic signs of cardiac tamponade will usually correlate clinically with a hypotensive patient, it is not always the case.