Intro to EKG Flashcards
P wave
atrial depolarization
QRS
ventricular depolarization
T wave
ventricular repolarization
U waves
inconsistent
PR interval
From onset of P wave to onset of QRS is measure of AV node conduction time. Normal is 0.12-0.20 seconds
QT interval
From onset of Q to end of T, represents total duration of depolarization and repolarization
How to calculate HR from EKG
HR= 300/ # heavy lines btw QRS’s OR HR= 1500/ #mm btw QRS’s
What are EKG leads
Electrodes that measure the difference in electrical potential btw: two different points (bipolary leads) on the body or one point on th body and a virtual reference point with zero electrical potential located in center of heart (unipolar leads)
Describe polarity on EKG. Which direction will QRS be in left, lateral and right sided leads?
Depolarization moving toward a positive electrode produces a positive deflection. QRS is + in left and lateral, and - in right leads
Describe placement of bipolar limb leads
lead I (+ on one handt, - on other hand), lead II (- on hand, + on foot), lead III (+ on foot and - on hand)
Describe placement of augmented limb leads
Unipolar leads. aVL (+ on left wrist), aVR (+ on right wrist), aVF (+ on ankle)
What are lateral leads
lead I and aVL : reflect lateral wall changes
What are inferior leads:
lead II, III and aVF: reflect inferior wall changes
What do the right chest and left chest leads measure
Right chest leads (V1 and V2) moniter RV. Left chest leads (V5 and V6) monitor LV
EKG of ventricular hypertrophy
more muscle= more volts= greater amplitude. Left ventricle hypertrophy shows big R waves in left sided leads (I, aVL, V5, V6). Right ventricle hypertrophy shows big R waves in right sided leads (V1, V2)
