Electrophysiology Conduction Pathway

Question 1

Dominant pacemaker

Answer 1

Sinoatrial (SA) Node

Question 2

Location of SA Node

Answer 2

Right atrium, near the inlet of superior vena cava

Question 3

Function of the SA node

Answer 3

Receives blood from the right coronary artery

Question 4

Intrinsic rate of SA node

Answer 4

60-100 bpm

Question 5

Intrinsic rate if AV junction

Answer 5

40-60bpm

Question 6

Location of Atrioventricular (AV) node

Answer 6

Posterior septal wall, right atrium

Question 7

Function of the AV valve

Answer 7

• Delays impulse conduction
• Allows time for atria to empty blood into ventricles

Question 8

Location of Bundle branches- Ventricles

Answer 8

Interventricular septum

Question 9

Function of Bundle Branches- Ventricles

Answer 9

Relays impulses to purkinje fibres

Question 10

Intrinsic rate of Bundle Branches- Ventricles

Answer 10

20-40 bpm

Question 11

Location of Purkinje Fibres- Ventricles

Answer 11

Ventricular myocardium

Question 12

Functions of Purkinje Fibres- Ventricles

Answer 12

Relays impulses to myocardium

Question 13

Intrinsic rate of Purkinje Fibres- Ventricles

Answer 13

20-40 bpm

Question 14

An abnormal condition in which either cardiac cells are not normally associated with a pacemaker function, begin to depolarize spontaneously OR pacemaker site other than SA node increases its firing rate beyond that which is considered normal

Answer 14

Enhanced Automaticity

Question 15

Occur during repolarization (after depolarizations) when cells are normally quiet

Answer 15

Abnormal Electrical Impulses

Question 16

• Slowed: all impulses are conducted, but it takes longer than normal
• Intermittent- Some impulses are conducted

Answer 16

Partial Conduction block

Question 17

No impulses are. conducted through the affected area

Answer 17

Complete Conduction Block

Question 18

An impulse returns to stimulate tissue that was previously depolarized

Answer 18

Reentry

Question 19

Precordial Lead

Answer 19

12 Lead ECG

Question 20

Wave of depolarization moving across myocardium

Answer 20

Positive Lead

Question 21

Towards positive electrode at left leg

Answer 21

Positive Deflection

Question 22

Away from negative electrode at left leg

Answer 22

Negative Deflection

Question 23

What is an artifact caused by?

Answer 23

• Muscle tremors
• Patient movement
• Loose electrodes/Poor contact
• Pacemaker activity
• Ambulance moving
• 60 cycle interference

Question 24

Views the inferior surface of the left ventricle

Answer 24

Lead II and Einthoven’s Triangle

Question 25

Vertical Axis is a measurement of

Answer 25

Voltage/amplitude (strength) of impulse - 1mm = 0.1 millivolt (mV) - 1 mV = 10 mm or 2 large boxes

Question 26

Horizontal axis is measurement of

Answer 26

Time - 5 large boxes = 1 second - 15 large boxes = 3 seconds - 30 large boxes = 6 seconds

Question 27

A straight line recorded when electrical activity is not detected. Defines positive or negative deflections. measures deviations above and below.

Answer 27

Baseline (isoelectric line)

Question 28

What does ST elevation indicate?

Answer 28

Cardiac event

Question 29

Movement away from baseline in either positive or negative direction

Answer 29

Waveform

Question 30

A line between waveforms; named by waveform that follows it

Answer 30

Segment

Question 31

Several waveforms

Answer 31

Complex

Question 32

First waveform preceding QRS complex. Normally upright, rounded in lead II

Answer 32

P Wave

Question 33

What does P wave indicate?

Answer 33

Atrial depolarization

Question 34

Times for PR interval

Answer 34

0.12-0.20 seconds - 3-5 small boxes - Start of P wave to the first deflection or Q wave

Question 35

Where is the PR segmant?

Answer 35

Part of the PR interval - Horizontal line between end of P wave and beginning of QRS complex - Normally isoelectric (flat)

Question 36

What does a Long PR interval indicate?

Answer 36

Impulse was delayed as it passed through atria, AV node or AV bundle

Question 37

What does a short PR Interval indicate?

Answer 37

This may be seen when impulse originates in atria close to AV node or AV bundle

Question 38

QRS Complex

Answer 38

- Q Wave - R Wave - S Wave - J point

Question 39

First downward deflection after P wave (often not present)

Answer 39

Q Wave

Question 40

First upward deflection after Q or P wave (always positive)

Answer 40

R Wave

Question 41

First downward deflection after R wave (always negative)

Answer 41

S Wave

Question 42

Small notch at the start of ST segmant

Answer 42

J Point

Question 43

- Normally narrow <0.12 sec (3 boxes) - Measured from beginning of Q or R wave to end of S wave

Answer 43

QRS Complex

Question 44

What does the QRS complex indicate?

Answer 44

- Ventricular depolarization - Atrial repolarization

Question 45

Normal Q Waves

Answer 45

Less than 0.03 seconds

Question 46

More than 0.03 seconds in duration or more that 30% of the following R wave height in that lead or both

Answer 46

Abnormal (pathologic) Q Wave

Question 47

- Measured from end of QRS complex to beginning of T wave - Normally flat

Answer 47

ST Segmant

Question 48

What does the ST segment indicate?

Answer 48

Early part repolarization of right and left ventricles

Question 49

First waveform following QRS complex, normally upright and slightly rounded in lead II

Answer 49

T Wave

Question 50

What does the T wave indicate?

Answer 50

Ventricular repolarization

Question 51

Portion of ECG tracing from beginning of the QRS complex to the end to T wave. Represents total ventricular activity

Answer 51

QT Interval

Question 52

Used to determine ventricular rate and regularity

Answer 52

R-R interval

Question 53

Main points from cardiac cycle

Answer 53

1. Venous blood fills both atria 2. Blood is ejected from the atria to ventricles 3. Blood is ejected from ventricles to pulmonary and systemic arteries

Question 54

What does ST elevation or depression Indicate?

Answer 54

Myocardial ischemia or injury