show me ur knowledge...

A 35 years old male, presents with intermittent, sharpe, misternal chest pain. the pain is somewhat worse with inspiration and associated with mild dyspnea. several weeks prior, he and his children had "cold" symptoms. what is the most likely diagnosis?

the pain is worse with inspiration and exertion following chest infection .. i think pericarditis

ur thinking is right...it is acute viral pericarditis...

now, what finding u may find when u examine this patient, and what r the ECG changes that may occur in acute pericarditis?

on examination there is pericardial friction rub.
ECG finding is st elevation in all the leads with carachteristic downward concavity

it's right...also there may be PR segment depression (not mentioned in davidson)....

NOW, if the patient developed dyspnea and the percardial friction rub disappeared? what do u suspect? and what investigation u may do to confirm ur suspecsion?

If the friction rub disappear & the dyspnea remain we think of Pericardial effusion that progress to cardiac tamponade ..... so to make sure about it , send the patient for Echo ..... CT or MRI scan can be usefull.

It is viral pericarditis and as mohmed said it became pericardial effusion
and the ECG FINDING in pericardial effusion would be (as i think) is a low voltage in all leads

ur answer is right dear mohammed....