Electrocardiography

Question 1

Electrophysiology

Answer 1

Branch of physiology concerned with the recording and analysis of the electrical activity of the heart

Question 2

Electrocardiogram

Answer 2

Recording of electrical potentials produced by cardiac tissues as recorded from the surface of the body

Question 3

Electrogram

Answer 3

Graphic recording of electrical activity of heart from surface of heart

Question 4

Instantaneous vector

Answer 4

Net voltage measured on the body surface

The algebraic sum of all the myocardial action potentials moving in many directions

Question 5

Voltage of instantaneous vector

Answer 5

Number of cells being depolarized or repolarized at any instant

Question 6

Direction of instantaneous vector

Answer 6

Depends on which anatomic regions of the heart is dominant at that instant

Question 7

Series of instantaneous vectors representing the depolarization of the atria

Answer 7

P vector

Question 8

Series of instantaneous vectors representing the depolarization of the ventricles

Answer 8

QRS Vector

Question 9

Series of instantaneous vectors representing the repolarization of the ventricles

Answer 9

T vector

Question 10

Instantaneous vectors are summarized as

Answer 10

Initial, Mean, and Terminal vectors

Question 11

Average or mean vector

Answer 11

Mean magnitude, direction, and polarity for that time period

Question 12

P vector initial

Answer 12

(AIR) anteriorly, inferiorly, rigtward

Question 13

P vector mean

Answer 13

(AIL)Anteriorly, inferiorly, leftward

Question 14

P vector terminal

Answer 14

Posteriorly, inferiorly, leftward

Question 15

QRS vector initial

Answer 15

Anteriorly, inferiorly, rightward

Question 16

QRS vector

Answer 16

Posteriorly, inferiorly, leftward

Question 17

QRS vector terminal

Answer 17

Posteriorly or anteriorly, inferiorly or superiorly, leftward or rightward

Question 18

T vector

Answer 18

Posteriorly, inferiorly, leftward

Question 19

Cancellation effects

Answer 19

90% of the vectors during cardiac depolarization and repolarization are directed in opposite directions

Question 20

Plane of view by limb leads

Answer 20

Frontal plane

Question 21

Plane of view for chest leads

Answer 21

Horizontal or transverse plane

Question 22

Bipolar limb leads

Answer 22

Diff of electrical potential between two sites, Leads I-III

Question 23

Lead I

Answer 23

+ left arm, - right arm

Question 24

Lead II

Answer 24

+left leg, - right arm

Question 25

Lead III

Answer 25

+left leg, - right arm

Question 26

Einthoven triangle

Answer 26

Apices: shoulders and pubic region Central battery: heart Triaxial reference figure of Bayley

Question 27

Unipolar limb leads

Answer 27

Potentials are compared to 0 and not to another potential

Question 28

Lead aVR

Answer 28

Right arm

Question 29

Lead aVL

Answer 29

Left arm

Question 30

Lead aVF

Answer 30

Left foot

Question 31

Hexaxial reference figure

Answer 31

Incorporation of axes of all limb leads

Question 32

V1 and V2

Answer 32

Anterior; facing epicardial surface of right ventricle

Question 33

V3 and V4

Answer 33

Septal; transition zone

Question 34

V5 and V6

Answer 34

Faces the epicardial surface of left ventricle; lateral

Question 35

Electrographic paper horizontal lines

Answer 35

Time; 1mm = 0.04 sec

Question 36

Electrographic paper vertical lines

Answer 36

Voltage; 10mm = 1mV

Question 37

Recording speed of electrocardiograph

Answer 37

25mm per second

Question 38

P wave

Answer 38

<0.10 sec; amp = 2-3mm

Question 39

T wave

Answer 39

<5mm for limb leads <10mm for chest leads 0.10-0.25 sec

Question 40

U wave occurence

Answer 40

Sinus bradycardia, hypokalemia, quinidine therapy

Question 41

PR interval

Answer 41

0.12-0.2 sec; prolonged in AV block

Question 42

QRS interval

Answer 42

<0.10 sec for limb leads | <0.11 sec for chest leads

Question 43

QT interval

Answer 43

Ventriclular electric systole; 0.28-0.45seconds

Question 44

ECG provides insights on

Answer 44

Anatomic orientation of the heart Relative sizes of cardiac chambere Variety of disturbances of rhythm and conduction Extent, location, and progress of ischemic changes to myocardium Effects of altered electrolyte concentrations and influence of certain drugs

Question 45

The ff should be examined in an ECG

Answer 45

Rhythm, Rate,P wave, QRS complex, T wave, PR interval, QRS interval, ST segment, Mean elctrical axis

Question 46

Left axis deviation

Answer 46

If axis < -30 degrees | Occurs in short stocky people and in left ventricular hypertrophy

Question 47

Right axis deviation

Answer 47

>+90 degrees | Occurs in tall and thin people and in Right ventricular hypertrophy