ECG Flashcards
(70 cards)
1
Q
Which node initiates a current of depolarization?
A
- SA node
2
Q
What occurs during P wave?
A
- Atrial muscle depolarization
3
Q
What occurs during PR interval?
A
- Conduction from SA through AV node
4
Q
What happens during QRS wave?
A
- Ventricular muscle depolarization
5
Q
What happens during QT interval?
A
- Time it takes for ventricular muscle to depolarize and repolarize
6
Q
What happens during T wave?
A
- Ventricular muscle repolarization
7
Q
What is a lead?
A
- Evaluation of the electrical field from different aspects of the body
- Different from a lead wire or electrode on the body
8
Q
How many leads are there?
A
- 6!
- All 6 leads calculate your mean axis
9
Q
Which lead is most commonly used for measurements?
A
- Lead II
- Moving from base to apex, right to left
10
Q
Positive deflection vs negative deflection on an ECG
A
- Toward the positive electrode, a positive deflection is observed in that lead
- Away from the positive electrode, a negative deflection occurs
11
Q
Polarity of QRS
A
- Normally a large positive on lead II, due to large muscle mass of the left heart
- If QRS is negative and leads are in correct position, means that there is right ventricular enlargement
12
Q
Mean electrical axis
A
- QRS in all six leads is used to calculate actual # degree of axis
- Also gives information about ventricular enlargement
13
Q
Is lead II QRS normally positive or negative in dogs and cats?
A
- POSITIVE
14
Q
What is ECG BEST for evaluating (2 main things)
A
- Heart rate
2. Heart RHYTHM and conduction
15
Q
What can ECG tell you about cardiac chamber enlargement?
A
- It can tell you about cardiac enlargement
- Specific but NOT VERY SENSITIVE
- If you see a change, it exists; if you don’t see changes, doesn’t mean that they don’t exist
16
Q
ECG and CHF or quality of cardiac muscle contraction
A
- CAN NOT tell you about presence of CHF or quality of cardiac muscle contraction
17
Q
What are two primary reasons to obtain an ECG in practice?
A
- Diagnose an arrhythmia detected on physical examination
- Search for an arrhythmic cause of syncope/collapse
18
Q
Other reasons to obtain an ECG?
A
- Assess cardiac size (knowing that a normal ECG does not exclude cardiac enlargement)
- Assess/monitor a critical patient post-HBC or GDV
- Individualize therapy for heart failure patients (monitor HR, rhythm)
- Monitor effectiveness of anti-arrhythmic therapy
- Evaluate patients with suspected drug toxicity (digoxin, etc.)
- Screen for electrolyte abnormalities (hyperkalemia, etc.)
- Look for supportive evidence of other disease processes
19
Q
What might you see with pericardial effusion on ECG?
A
- Low-voltage complexes, electrical alternans
20
Q
What might you see with hypothyroidism on ECG?
A
- Low-voltage complexes
21
Q
What might you see with hypoadrenocorticism on ECG?
A
- Bradycardia, spiked T wave, flat P wave
22
Q
Types of ECG equipment
A
- Standard vs rhythm monitoring
23
Q
Which type of ECG can you measure complexes with?
A
- Standard/in hospital/diagnostic
24
Q
Rhythm monitoring (surgical) ECG use
A
- Not diagnostic
- Rhythm and heart rate machine
- SHOULD NOT USE FOR CARDIAC CHAMBER ENLARGEMENT
25
Ambulatory monitor definition
- Portable device that records ECG while the animal is in home surroundings (AKA Holter monitor)
26
Ambulatory monitor indication
- Evaluating collapsing patients for intermittent arrhythmia or monitor response to anti-arrhythmic therapy
27
What are the four steps of ECG interpretation?
1. Evaluate ECG for artifacts, quality and calibrations
2. Determine heart rate
3. Name the cardiac rhythm
4. Evaluate the P-QRS-T complex configurations and morphologies
28
Standard calibration for ECG complex height
- 1 cm (10mm) = 1 mV
29
ECG complex width
- Duration can indicate cardiac chamber enlargement
| - Complex duration - horizontal axis or paper speed
30
What speed are P-QRS-T measurements typically made at?
- 50mm/sec
| - 1 small box = 0.02 sec
31
Why quality and calibrations?
- Values are measured for duration and amplitude of P wave and R wave
- Measurements indicate heart enlargement or electrical conduction abnormalities
32
Dogs normal HR on ECG
- 60-160 BPM
| - Can be as low as 120 in the home environment
33
Cats normal HR on ECG
- 140-220 BPM
| - Can be as low as mid 20s to 30s for sleeping dogs
34
Other reference ranges for ECG
- P wave (max)
- PQ interval
- QRS (width)
- R wave (max)
- ST segment
- T wave (max)
- QT interval
SEE SLIDES and also ask if this is important?
35
What can happen with artifacts?
- Affect ability to interpret the electrocardiogram by basking the real ECG or appearing similar to an arrhythmia
- Common examples: Purring, respiration movement, motion, muscle twitches
36
How many boxes to count for HR at 50 mm/sec?
- 30 boxes for 3 sec, then multiply by 20
| - Bic pen is exactly 3 seconds on 50 mm/sec speed
37
How many boxes to count for HR at 25 mm/sec?
- 15 boxes is 3 seconds
38
Normal horse heart rate
- 28-40 BPM
39
Normal cow heart rate
- 70-90 BPM
40
2 normal rhythms in dogs
- Sinus rhythm
| - Sinus arrhythmia
41
Sinus rhythm characteristics
- Normal P wave
- Normal heart rate
- Normal, similar shaped P wave for every QRS
- Normal, similar shaped QRS for every P wave
- Regular, very little variation in P-P interval (<10%)
42
Sinus arrhythmia characteristics
- Irregular rhythm originating from the SA node, but normal in many species
- Defined by normal heart rate
- Normal shaped P wave (some variation in height okay; "wandering" pacemaker of vagal tone)
- Normal QRS for every P wave
- Pattern of increasing and decreasing heart rate that is regularly irregular
43
What is the cause of a sinus arrhythmia?
- Pronounced vagal tone
| - SOMETIMES associated with respiration
44
What are the normal rhythms in cats?
- JUST ONE
| - Sinus rhythm or sinus tachycardia
45
Normal rhythms in bovines
- Sinus rhythm
| - Sinus bradycardia may be associated with a lack of food intake
46
Normal rhythms in equines
- Normal sinus rhythm
- Sinus arrhythmia
- Second degree atrioventricular block (vagal tone species)
47
Morphology of complex assessment
- Are complex measures within normal range for amplitude and duration?
- Do P waves look different?
- Do QRS waves look different?
48
Normal variations in ECG
- In some animals, Q wave may not be present or S wave may not be visible
- T wave can be small, positive, negative, or biphasic
49
Normal P wave, deep S wave rule out
- Right ventricular enlargement
| - HIS bundle branch block
50
Big T wave meaning
- Hyperkalemia
| - Maybe if you have ventricular depolarization abnormalities and expect to see repolarization abnormalities
51
Meaning of Tall P wave
- Right atrial enlargement in dogs
- Right or left atrial enlargement in cats
- Sinus tachycardia in dogs
52
Meaning of Tall R wave***
- Left ventricular enlargement
53
Meaning of Wide P wave
- Left atrial enlargement in dogs and cats
| - Pseudo abnormality
54
Absent p wave meaning
- Hyperkalemia
- Atrial standstill
- SIlent atrium or atrial fibrillation
55
P height variation
- Wandering pacemaker (normal finding with sinus arrhythmia), atrial or junctional premature beats
56
Meaning of shortened PR interval
- High sympathetic tone
57
Meaning of prolonged PR interval
- First degree AV block
58
Meaning of deep Q wave
- normal variation in deep-chested dogs; biventricular enlargement potentially
59
Meaning of wide QRS
- Ventricular enlargement; intraventricular conduction disturbance
60
Meaning of small QRS
- Normal variation; pericardial or pleural effusion; pneumothorax, hypothyroidism, obesity
61
Meaning of large T wave
- Myocardial hypoxia, interventricular conduction disturbance, bradycardia, ventricular enlargement, hyperkalemia
62
Meaning of small T wave
- Same as for small QRS, normal for cats
63
Meaning of dep S wave
- Normal variation; right ventricular enlargement; left ventricular hypertrophy (in leads II, III, and aVE? ONLY)
64
Ectopic beat definition
- Complex with abnormal shape may come from a different location of the heart (not from sinus node)
65
Where can ectopic beats come from?
- Atria or ventricle
66
Premature vs escape beats
- Premature is earlier than expected
| - Escape is later than expected
67
Supraventricular complex appearance
- QRS looks similar, but P wave looks different (or in junctional, are absent)
- Timing will usually be early
- QRS is the same!
68
Ventricular complex appearance
- Wide and bizarre
- Nothing like a sinus rhythm
- Look to sinus beats to see if there is chamber enlargement
69
How do you differentiate escape beats and premature beats?
- Escape and premature beats can look morphologically the same
- Differentiated by timing (early or late) compared to preceding complexes
70
What four things to assess with morphology of complexes that appear different from the rest?
- Which beat is it?
- Is it ventricular or supraventricular?
- Is it premature or delayed?
- What would you call it?
