Physiological Basis of the ECG

Question 1

What is the acceptable voltage for the P wave?

Answer 1

.1 to .3 mv

Question 2

What two leads are considered septal/RV?

Answer 2

V1 and V2

Question 3

What artery is associated with the anterior and septal leads(V1, V2, V3, V4)?

Answer 3

Left anterior descending

Question 4

What artery is associated with the inferior leads(Leads II, III, aVF)?

Answer 4

Right coronary artery

Question 5

What leads are considered anterior?

Answer 5

V3, V4

Question 6

What artery is associated with the lateral leads(Lead I, aVL, V5, V6) ?

Answer 6

Circumflex Artery

Question 7

What is the outside acceptable voltage for the QRS complex from peak of the R to bottom of the S?

Answer 7

1.0 - 1.5 mV

2 - 3 boxes.

Question 8

What is the acceptable voltage for the T wave?

Answer 8

.2 to .3

Question 9

How long is the outer limit of the PR interval?

Answer 9

.2 seconds

Question 10

What leads are considered lateral?

Answer 10

V5, V6, I, aVL

(The leftmost ones)

Question 11

What leads are considered “inferior?”

Answer 11

II, III, and aVF

Question 12

What is the mean electrical axis deviation?

Answer 12

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.

Question 13

What are chest/precordial leads?

Answer 13

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)

Question 14

When will a positive deflection in the EKG be seen?

Answer 14

If AP is spreadin towards a positive lead of the electrode, a positive deflection will be observed.

Question 15

What are the augmented limb leads?

Answer 15

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

Question 16

What are the standard bipolar limb leads?

Answer 16

1=right arm to left arm

2=right arm to left leg

3=left arm to left leg

Question 17

Know how to calculate heart rate from an ECG

Answer 17

Time between dark lines-0.2sec

Time between light lines-0.04sec

Question 18

What is the PR segment?

What is the ST segment?

Answer 18

end of atrial depolarization until beginning of QRS

end of QRS until beginning of T wave

Question 19

What is the PR interval?

What is the QT interval?

Answer 19

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)

Question 20

What do the segments represent on an EKG?

What do the intervals represent on an EKG?

Answer 20

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

Question 21

What is the U wave?

Answer 21

not typically seen

delayed repolarization of purkinje fibers maybe? no one really knows what it does

Question 22

What is the T wave?

Answer 22

represents phase 3 (repol.) of AP in ventricular muscle

Question 23

What is the QRS complex?

Answer 23

represents phase 0 of AP in ventricular muscle

Na conduction increases in ventricles

Question 24

What is the P wave

Answer 24

represents phase 0 of AP in atrial muscle

K permeability is high between P-Q

Question 25

What is the ECG tracing deflection?

Answer 25

negative towards base an positive towards apex

Question 26

EKGs do not report differences between the atria and ventricles because

Answer 26

they are electrically insulated