Physiological Basis For ECG & Basic ECG Flashcards
SA node causes _______________ to ____________________ from ___________ to ___________ - _____ wave
Atria Depolarize Right Left P
_______________ delays signal-________ interval
AV node
PR
Ventricles ________________ generally from ___________ to _____________ and from _____________ to _____________-____________ complex
Depolarize Right Left Apex Base QRS
Action potential phase _____ delays __________________ of __________________-_______ segment
2
Repolarization
Ventricles
ST
Ventricles _______________ generally from ______________ to ______________ and ______________ to ______________-__________ wave
Repolarize Left Right Base Apex T
The __________ wave represents phase 0 of the AP’s spreading through the atrial muscle
P
The _____________ complex represents phase 0 of the AP spreading throughout the ventricles
QRS
The _________ wave represents phase 3 or repolarization of ventricular muscle fibers spreading through the ventricles
T
PR segment
End of atrial depolarization until beginning of QRS
ST segment
End of QRS until beginning of T wave
PR interval
Beginning of P wave until beginning of QRS
QT interval
Beginning of QRS until end of T wave
Heart rate on ECG
300, 150, 100, 75, 60, 50
OR
60/(big boxes * 0.2) + (small boxes * 0.04)
Standard (bipolar) limb leads
1-right arm to left arm
2-right arm to left leg
3-left arm to left leg
Augmented limb leads
-aVF (augmented vector, foot) (RA+LA) to LL -aVR (augmented vector, right) (LL+LA) to RA -aVL (LA) (augmented vector, left) (LL+RA) to LA
Chest or precordial leads
V1-6 (vectors 1 through 6)
Einthoven’s Triangle
Standard limb leads axis
Each lead is assigned a positive and negative polarity and the voltage between them measured
Augmented limb leads directionality
One of the limb leads is assigned a positive polarity and the remaining 2 electrodes are averaged and assigned a negative polarity
Chest or precordial leads directionality
Precordial leads not assigned an axis
Instead assigned regions of the heart
Each lead acts as the positive electrode
Inferior wall leads
II, III, aVF
Septal heart leads
V1, V2
Anterior heart leads
V3, V4
Lateral heart leads
V5, V6, I, aVL
I and aVF up
Normal axis
I and aVF both down
Extreme right axis deviation
I up and aVF down
Left axis deviation
1 down and aVF up
Right axis deviation
_____ wave begins before atrial ______________
P
Contraction
___________ begins before ventricular __________________
QRS
Contraction
________ wave begins before ventricular _______________
T
Relaxation
