Ultrasound
Pericardial effusion
Tamponade physiology (e.g. RV diastolic collapse)
Doppler interrogation across the mitral valve will demonstrate exaggerated respiratory variability of transvalvular flow (due to the phenomenon of ventricular interdependence)
ECG
Tachycardia (bradycardia is ominous finding)
Normal or low voltage
Electrical alternans
Low voltage QRS
CXR
Enlarged cardiac silhouette
Pulsus paradoxus
>10mmHg change in systolic BP on inspiration
Direct visualization on thoracotomy (if indicated)
Pericardial effusion
Tamponade physiology (e.g. RV diastolic collapse)
Doppler interrogation across the mitral valve will demonstrate exaggerated respiratory variability of transvalvular flow (due to the phenomenon of ventricular interdependence)
Tachycardia (bradycardia is ominous finding)
Normal or low voltage
Electrical alternans
Low voltage QRS
Enlarged cardiac silhouette
>10mmHg change in systolic BP on inspiration
Myocardial rupture
Acute coronary syndromes 
Coronary artery dissection
STEMI
Pericardial effusion and tamponade
Non-STEMI
Globe rupture
Unstable angina