Physiological Basis of the ECG Flashcards
What is the acceptable voltage for the P wave?
.1 to .3 mv
What two leads are considered septal/RV?
V1 and V2
What artery is associated with the anterior and septal leads(V1, V2, V3, V4)?
Left anterior descending
What artery is associated with the inferior leads(Leads II, III, aVF)?
Right coronary artery
What leads are considered anterior?
V3, V4
What artery is associated with the lateral leads(Lead I, aVL, V5, V6) ?
Circumflex Artery
What is the outside acceptable voltage for the QRS complex from peak of the R to bottom of the S?
1.0 - 1.5 mV
2 - 3 boxes.
What is the acceptable voltage for the T wave?
.2 to .3
How long is the outer limit of the PR interval?
.2 seconds
What leads are considered lateral?
V5, V6, I, aVL
(The leftmost ones)
What leads are considered “inferior?”
II, III, and aVF
What is the mean electrical axis deviation?
The average direction of spreading AP in ventricles, usually right to left
- helps determine heart condition
- uses average amplitude of QRS in leads I and aVF
- if it spreads to upper left-left axis deviation
- if it spreads to right-right axis deviation
- shifted by hypertrophy, MI, heart replacement, BBB, etc.
What are chest/precordial leads?
no axis
assigned regions of the heart
each lead acts as a positive electrode (says one slide, other slide says V1-2 is mainly negative?)
(V1, 2, 3, 4, 5, 6)
When will a positive deflection in the EKG be seen?
If AP is spreadin towards a positive lead of the electrode, a positive deflection will be observed.
What are the augmented limb leads?
aVF=augmented vector (foot) including Right Arm and Left Arm to left leg
aVR=augmented vector, right from Left leg and Left Arm to Right Arm
aVL=augmented vector, left from left leg and right arm to left arm
What are the standard bipolar limb leads?
1=right arm to left arm
2=right arm to left leg
3=left arm to left leg
Know how to calculate heart rate from an ECG
Time between dark lines-0.2sec
Time between light lines-0.04sec
What is the PR segment?
What is the ST segment?
end of atrial depolarization until beginning of QRS
end of QRS until beginning of T wave
What is the PR interval?
What is the QT interval?
beginning of P wave until beginning of QR. This is often referred to sa the PQ interval, but since the Q wave is absent and the QR interval is very small (0.16ms)
beginning of QR until end of T wave (0.35ms)
What do the segments represent on an EKG?
What do the intervals represent on an EKG?
represents the duration of a single event on the ECG
represents the duration of two or more events
horizontally-5 large boxes=1s
vertically-2 large boxes=1.0mv
What is the U wave?
not typically seen
delayed repolarization of purkinje fibers maybe? no one really knows what it does
What is the T wave?
represents phase 3 (repol.) of AP in ventricular muscle
What is the QRS complex?
represents phase 0 of AP in ventricular muscle
Na conduction increases in ventricles
What is the P wave
represents phase 0 of AP in atrial muscle
K permeability is high between P-Q
