ECG Flashcards
how can you tell the P wave is from the SA node?
its the one that looks normal
how can you tell that conduction was initiated at the AV node?
will be negative deflections where there should be positive
narrow QRS complex?
indicates junctional rhythm
rhythm initiated at AV node
negative deflected P wave?
initiated at the AV node
-going in the opposite direction of normal
what if all P wave have different morphology?
if all positive - from atrium
what if P wave is absent or upside down and irregular?
junctional escape complex
how do you know if the P wave is too large?
height less than 2.5mm lead II
width less than 0.12s lead II
often biphasic lead V1
what is the significance of large P waves?
atrial hypertophy
what is the PR interval?
AV nodal delay
what is a clinically important aspect of PR interval?
need atria to empty before beating
average length of PR interval?
up to 0.2s
what is the QRS?
ventricular depolarization
must it always have a Q wave to be a QRS complex?
no
what is the significance of a Q wave?
depolarization left to right across IV septum
first negative deflection (if there is one)
are Q waves abnormal?
no
