Tamponade or PE?

Today we discussed a tricky case of a patient with both a pericardial effusion and a pulmonary emobolism. When they developed shock, the question became is this tamponade or a massive PE?

On physical exam, both groups of patients will have:

- sinus tachycardia

- hypotension

- high JVP

In tamponade: muffled heart sounds, pericardial friction rub, pulsus paradoxus

In massive PE: signs of DVT

Note that an increased pulsus (ie>10 mmHg) can also be seen in other conditions: profound hemorrhagic shock, obstructive lung disease... and massive pulmonary embolism!

In an unstable patient, bedside investigations would include an ECG...

ECG findings of tamponade: 

- sinus tachycardia

- low voltages (ie less than 5 in limb leads, less than 10 in precordial leads)

- pericarditis findings: ST elevation, PR depression

- electrical alternans (beat-to-beat variation in QRS amplitude, caused by swinging of the heart in the pericardial fluid) - rare but very specific.

ECG findings of pulmonary embolism:

- sinus tachycardia

- atrial arrhythmias

- S1Q3T3-rare but specific ECG pattern

- iRBBB/RBBB

- RAD

- non-specific ST/T wave changes

- precordial T-wave inversion (Rt heart strain pattern)

To definitively sort these two out, an echocardiogram is needed. 

Echocardiogram findings of massive PE:

- Increased RV size

- Decreased RV function

-Tricuspid regurgitation

Echocardiogram findings of tamponade:

- RA/RV diastolic collapse

- ventricular interdependence: reciprocal respiratory variation in volume in right and left heart, as well as flows across AV valves (as in figure above).

- IVC full, collapses by less than 50% on inspiration

Check out this NEJM review on Acute Cardiac Tamponade