Module 3: C7: ECG 1

Question 1

Basis of ECG:
Action potentials are happening in the _______________ level

Answer 1

Cellular

Question 2

Basis of ECG:
Phase 0 ->

Answer 2

P wave | QRS complex

Question 3

Basis of ECG:
Phase 3 ->

Answer 3

ST segment and T wave

Question 4

What is the type of ECG that we use in large animal species?

Answer 4

Base-Apex Lead

Question 5

Base-Apex Lead in Large Animals:
- (-) electrode or white electrode goes on the =>
- (+) electrode or Black electrode goes on the =>

Answer 5

• RIGHT jugular furrow or scapular spine (“right arm”)
• LEFT apex (“left arm”)

Question 6

Frontal Leads: Einthoven’s Triangle
Right arm to (-) –> Left arm (+)

Which lead is this?

Answer 6

Lead I

Question 7

Frontal Leads: Einthoven’s Triangle
Right arm (-) –> Left leg (+)

Which lead is this?

Answer 7

Lead II

Question 8

Frontal Leads: Einthoven’s Triangle
Left arm (-) –> Left leg (+)

Which lead is this?

Answer 8

Lead III

Question 9

Frontal Leads: Einthoven’s Triangle
Summed left arm and left leg (-) –> Right arm (+)

Answer 9

aVR

Question 10

Frontal Leads: Einthoven’s Triangle
Summed right arm and left leg (-) –> Left arm (+)

Answer 10

aVL

Question 11

Frontal Leads: Einthoven’s Triangle
Summed right and left arm (-) –> Left leg (+)

Answer 11

aVF

Question 12

Genesis of the ECG:
1. Impulse starts in the _____ node

Answer 12

SA

Question 13

Genesis of the ECG:
2. The signal travels through atria and _____ node

Answer 13

AV

Question 14

Genesis of the ECG:
3. Signal travels through ___________ system

Answer 14

His-Purkinje

Question 15

Genesis of the ECG:
4. Ventricular ____________

Answer 15

depolarization = Increases the membrane potential

Question 16

Genesis of the ECG:
5. Ventricular ____________ (T-Wave)

Answer 16

repolarization = Decreases the membrane potential, restoring the resting membrane potential

Question 17

ECG Paper:
When using 50 mm/sec paper speed, how many seconds is each little box?

Answer 17

0.02 secs (20 msec)

Question 18

ECG Paper:
What is the baseline of an ECG?

Answer 18

Horizontal line preceding P wave

Question 19

ECG Paper:
What are deflections?

Answer 19

Waves (positive or negative)

Question 20

ECG Paper:
The paper speed is represented by which axis?

Answer 20

X-axis
- 25 mm/sec
- 50 mm/sec
(the higher the heart rate, the higher the speed we use)

Question 21

ECG Paper:
The sensitivity is represented by which axis?

Answer 21

Y-axis
- also called Amplitude
- 10 mm/mV
- 5 mm/mV
- 20 mm/mV

Question 22

Determining Heart Rate:
Describe the Instantaneous HR Method
- Count: ____________
- Paper speed? _____
- Divide: ____________

Answer 22

• 42 little boxes between complexes
• 25 mm/sec
• 1500/42 = 36 bpm
  If paper speed is 50 mm/sec then take 3000/# little boxes

Question 23

Determining Heart Rate:
Describe the Average HR Method
- Paper speed? 25 mm/sec
- Count amount of time: 3 or 6 seconds (the more seconds you count, the more representative is going to be)
- Count number of complexes in that time: 2
- Extrapolate to 1 minute: _____________

Answer 23

2 complexes in 3 seconds, 3 seconds x 20 = 60 seconds; 2 x 20 = 40 bpm

Question 24

(T/F) When referring to a regular vs irregular rhythm, it means that normal vs abnormal

Answer 24

False
- perfectly spaced R to R intervals
- Premature beats? Pauses? are there any repetitive patterns?

Question 25

Sinus rhythms: Normal sinus rhythm Fill in the blanks of the Normal Ranges for the following species: 1. Dogs: _____ - _____ bpm 2. Cats: _____ - _____ bpm 3. Equine: _____ - _____ bpm (must know this)

Answer 25

1. 60 - 160 2. 140 - 240 3. 35 - 50

Question 26

Sinus rhythms: Definition - Very common and normal in large animals and dogs (abnormal in Cats -> high sympathetic tone in hospital) - Associated with variable vagal tone - Often associated with respirations (i.e. respiratory sinus arrhythmia) - Inspiration: faster - Expiration: slower

Answer 26

Sinus arrhythmia

Question 27

Sinus rhythms: In combination with Sinus arrhythmias, we can have a "Wandering pacemaker" which is ...

Answer 27

- Gradual change in the morphology of the P waves - Often associated with RSA (respiratory sinus arrhythmia) and high vagal tone - Shifts in the pacemaker from within the sinus node

Question 28

(T/F) Sinus arrhythmia is normal in cats

Answer 28

False, NEVER normal in cats, look for cause of high vagal tone

Question 29

Sinus rhythms: Sinus tachycardia - "warm up" and "cool down" - Sometimes the P waves are buried in the T waves What would be considered tachycardia for the following species? 1. Dogs: > ________ bpm 2. Cats: > ________ bpm 3. Equine: > ________ bpm

Answer 29

1. 150/160 2. 220 3. 70

Question 30

Sinus rhythms: Sinus bradycardia What would be considered bradycardia for the following species? 1. Dogs: < _______ bpm 2. Cats: < _______ bpm 3. Equine: < _______ bpm

Answer 30

1. 60 2. 140 3. 35

Question 31

Definition: Average direction of electrical potential generated by the heart during the cardiac cycle

Answer 31

Mean electrical Axis (MEA)

Question 32

Mean Electrical Axis: What is the normal range in a cat?

Answer 32

0-160 degrees

Question 33

Mean Electrical Axis: What is the normal range in a dog?

Answer 33

45-100 degrees

Question 34

What is the most common lead we would be looking at?

Answer 34

Lead II

Question 35

Determining MEA: Describe the Simplified approach.

Answer 35

- Look at your ECG leads (Ideally 6 leads) - Look at the direction the QRS in each lead - Starting with the most positive and most negative - Envision these against Einthoven's triangle - Determine the general direction of electrical activity

Question 36

Determining MEA: Simplified approach For normal axis: - QRS is usually _______ (neg/pos) - II, III, avF - QRS is either isoelectric or positive in lead ___ - QRS should be _______ (neg/pos) - avR - QRS is either isoelectric or negative in _____

Answer 36

- Positive - Lead I - Negative - aVL

Question 37

What can it mean when you have axis deviation?

Answer 37

- Conduction abnormality - Cardiac remodeling

Question 38

- Deep S waves in leads I, II, aVF (negative complexes) - Positive QRS in aVR (may be positive in III) - Possible causes: right ventricular enlargement, right bundle branch block What axis deviation is this?

Answer 38

Right axis deviation

Question 39

- Lead I & aVL are tallest (usually lead II & aVF are tallest) - Possible causes: Left bundle block, Left ventricular enlargement What axis deviation is this?

Answer 39

Left axis deviation

Question 40

Atrial Enlargement: What are we seeing with Right atrial enlargement?

Answer 40

Tall P waves (P-pulmonale)

Question 41

Atrial Enlargement: What are we seeing with Left Arial enlargement?

Answer 41

Wide P waves (P-mitrale)

Question 42

Right atrial enlargement on ECG: In the following species, what would be considered a tall P-wave in lead II? - Dogs: > ______ - Cats: > ______

Answer 42

- 0.4 mV - 0.2 mV

Question 43

Left atrial enlargement on ECG: In the following species, what would be considered a wide P-wave in lead II? - Dogs: >_____ - Cats: >_____ - Horses: >_____

Answer 43

- 40 ms (> 50 ms in large/giant breeds) - 35 ms - 160 ms

Question 44

In what species is seeing a "double hump" P-wave normal?

Answer 44

Horse

Question 45

What would it mean if the P-waves were tall and wide?

Answer 45

Biatrial enlargement

Question 46

- Deep S waves in Lead II - Negative QRS in I & II - Positive QRS in avR - Right axis deviation - Can indicate RV hypertrophy and/or dilation This is describing ...

Answer 46

Right ventricular enlargement

Question 47

(T/F) RV enlargement is a cause of a right axis deviation, but not all right axis deviations indicate RV enlargement

Answer 47

True

Question 48

- Tall R-waves in Lead II - QRS duration prolonged - +/- Left axis deviation - Doesn't work for large animals This is describing ...

Answer 48

Left ventricular enlargement