Med Term 3 > CVS 5 > Flashcards

CVS 5 Flashcards

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1
Q

Label the image.

A
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2
Q

What do the PR interval represent on an ECG?

What is the normal range?

A

time from start of P wave (atrial depolarisation) to the start of the QRS complex (ventricular depolarisation) = time taken for the impulse to travel from the atria through the AV node to the ventricles

0.12-0.20 seconds / 3-5 small squares

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3
Q

How much time is represented by 1 small square on an ECG?

A

0.04 seconds

(1 large square = 0.2 seconds)

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4
Q

How can you verify if an ECG is calibrated properly?

A
  • calibration box is 10 mm tall (1 mv deflection, 10 small squares)
  • standard paper speed: 25 mm/sec
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5
Q

What is the rhythm originating from the sinus node called?

What are key features of this rhythm?

A

sinus rhythm

key features:
- P waves present
- narrow QRS
- regular R-R intervals

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6
Q

What is the arrow pointing to?

A

SA node

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7
Q

What does the P-wave represent?

What is the normal duration of the P-wave?

A

atrial depolarisation

<120 ms (<3 small squares)

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8
Q

What is AF?

What are its key features on ECGs?

A

abnormal electrical activity in the atria - atria does not contract properly, fibrillates instead = atria bombard AV node with 300-600 impulses per minute, AV node cant conduct them all but it lets some through in an irregular pattern = tachycardia

key features:
- no P-waves (may have “wavy” baseline)
- narrow QRS
- irregular R-R intervals

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9
Q

What does the rhythm strip show?

A

AF

  • no p-waves (wavy baseline)
  • irregular R-R intervals
  • narrow QRS
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10
Q

What is a normal PR interval?

Give an example of a condition which would show a shortened PR interval.

A

0.12-0.2 seconds (3-5 small squares)

wolff-parkinson-white
- impulse bypasses AV node via bundle of kent
- ventricles get “pre-excited” = short PR

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11
Q

What does the PR interval cover?

Where does the pause happen?

A

atrial depolarisation -> AV node -> His-Purkinje -> ventricles

AV node

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12
Q

What is the name of the pathway linked to Wolff-Parkinson-White syndrome?

What wave is shown on WPW syndrome ECGs?

A

accessory pathway - Bundle of Kent that connects atria to the ventricles - bypass normal AV node delay

‘delta wave’ due to early conduction through accessory pathway = represents slow initial ventricular depolarisation

(short PR interval, wide QRS)

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13
Q

What condition is this seen in?

A

WPW syndrome

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14
Q

What are the two main types of 2nd-degree AV block?

Which one is more dangerous?

A

mobitz I
- PR interval gets progressively longer with each beat until one P wave is not followed by QRS complex

mobitz II - MORE DANGEROUS
- PR interval is constant/normal but then suddenly a QRS is dropped

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15
Q

What are the ECG key features of 1st degree heart block?

A
  • prolonged PR interval >200ms
  • R wave after every P wave
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16
Q

What does this rhythm strip show?

A

1st degree heart block

  • prolonged PR interval >200ms
  • R wave after P wave
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17
Q

What does this rhythm strip show?

A

2nd degree heart block - mobitz type I (aka wenchebach)

  • PR interval >200ms + successive prolongation with each beat
  • R wave after every P wave
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18
Q

What does this rhythm strip show?

A

(higher risk of progression to 3rd degree heart block)

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19
Q

What does this rhythm strip show?

A

3rd degree heart block (aka complete heart block) = atria and ventricle act independent of each other

  • no relation between P waves and QRS complex
  • atrial rate constant (60-100)
  • ventricular rate constant (20-40)
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20
Q

What are the ECG key features of a 3rd degree heart block?

A
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21
Q

What does the QRS complex represent?

What is its normal duration?

A

ventricular depolarisation

<120ms (<3 small squares)

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22
Q

What are the ECG key features of LBBB?

A
  • QRS >120ms (3 small squares)
  • dominant S wave in V1 (looks like a W)
  • notched “M” shaped R wave in V6

WiLLiaM = LBBB V1 + V6

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23
Q

What do the rhythm strips show?

A

LBBB

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24
Q

What occurs in LBBBs?

Why does the overall electrical impulse shift away from lead V1?

A

blockage of the left bundle branch causes left ventricle to depolarise late via slow muscle-to-muscle spread from the right ventricle

left bundle fails - right bundle activates first = causes right side of the septum to depolarise before the left = causes overall electrical impulse to shift away from lead V1

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25
In LBBB, in which lead would you see the following: - more negative QRS complex - small initial R wave followed by deep S wave
lead V1
26
What is the difference between left and right BBB?
27
What does the rhythm strip show?
monomorphic ventricular tachycardia rate >100 (all QRS complexes look the same, "mono" = one form)
28
What does the rhythm strip show?
polymorphic ventricular tachycardia e.g torsardes de pointes (QRS complexes vary in shape and size, "poly" = many forms)
29
What do the rhythm strips show?
ventricular fibrillation no identifiable p-wave, QRS complexes or t-waves
30
What is a premature ventricular complex? What are its key features?
premature ventricular complex - extra heartbeat that starts in the ventricles rather than following the normal sinus node -> AV node -> ventricles pathway key features - QRS >120ms (3 small squares) - abnormal QRS morphology - premature: no preceding P-wave, happens before next QRS is expected
31
What is shown on the ECG?
ventricular ectopics
32
What is the Sokolow-Lyon voltage criterion for LVH?
S wave in V1 + tallest R wave in V5 or V6 >35mm
33
What does a tall S in V1 + tall R in V5/V6 represent?
increased left ventricular muscle mass generating higher voltages
34
Why is R wave peak time prolonged in LVH?
because thicker myocardium takes longer to depolarise
35
Name 2 common causes of LVH.
hypertension aortic stenosis
36
What is the difference between LVH Voltage Criteria and Non-Voltage Criteria?
VOLTAGE - looks at how tall/deep the QRS complexes are - logic: bigger, thicker LV generates larger electrical voltages = taller R waves and deeper S waves BIG MUSCLE = BIG VOLTAGE NON-VOLTAGE - looks at timing and shape of depolarisation/repolarisation - logic: thick LV also SLOWS CONDUCTION and STRESSES REPOLARISATION
37
What does the ECG show?
LVH
38
What type of axis deviation is LVH? Explain what this means.
left axis deviation
39
What is the ECG criteria for RVH?
40
What does the ECG show?
right ventricular hypertrophy - R wave dominant in V1 - deep S wave in V5 or V6 - QRS <120ms
41
What do these criteria indicate?
right ventricular hypertrophy
42
What do these criteria indicate?
left ventricular hypertrophy
43
What are the key features of a PE?
44
What is the most common ECG finding for PEs?
sinus tachycardia
45
What does the ECG show?
PE
46
What are the normal features of a T-wave?
47
In regards to hyperkalemia, what would ECGs show at different blood levels?
5.5-6.5 = MILD = tall tented T waves 6.5-7.5 = MODERATE = loss of P waves + wide QRS 7.5++= SEVERE = sine wave pattern (QRS and T wave merge) -> VF
48
What would the following K+ levels show on an ECG?: 1. 5.5-6.5 2. 6.5-7.5 3. 7.5++
1. tall tended T waves 2. loss of P waves / wide QRS 3. sine wave pattern -> VF
49
What would cause this on an ECG?
hyperkalemia, >7.5
50
What does extracellular K+ affect? What is the difference between hyperkalemia and hypokalemia?
resting membrane potential hyper: RMP less negative (more depolarised) hypo: RMP more negative (hyperpolarised)
51
What would cause this ECG?
hypokalaemia
52
What are the ECG components of hypokalaemia?
53
What part of the myocardium is most vulnerable to ischaemic damage? What causes myocardial ischaemia?
subendocardium reduced perfusion to myocardium - often due to atherosclerosis in coronary arteries
54
What do ischaemic myocytes leak and what can this cause?
55
What is the difference between the two images? What occurs?
56
During local hyperkalaemia, what happens to the RMP and the cells?
RMP: less negative cells: permanently depolarised
57
What time of ischaemia does ST depression cause? (NSTEMI) What time of ischaemia does ST elevation cause? (STEMI)
subendocardial ischaemia transmural ischaemia
58
What is the difference in the images?
59
What does the ECG show?
STEMI - transmural infarction
60
What do the colours represent? What is each area supplied by?
purple - INFERIOR LEADS: II, III, aVF = INFERIOR SURFACE (mainly left ventricle) - RCA blue - LATERAL LEADS: I, aVL, V5, V6 - lateral wall of left ventricle - circumflex artery (branch of LCA) red (V1, V2) - SEPTAL LEADS - interventricular septum (anterior aspect) - LAD red (V3, V4) - ANTERIOR LEADS - anterior wall of left ventricle - LAD
61
What are the STEMI criteria?
62
What are the lines pointing to? What part of the heart does each supply?
63
What are the lines pointing to? What part of the heart does each supply?
64
Which ECG leads look at the inferior surface of the heart? Which ventricle surface do the inferior leads represent? Which coronary artery is usually involved in inferior MI?
leads II, III, aVF inferior surface of left ventricle RCA
65
Which ECG leads look at the lateral wall of the heart? The lateral leads represent which part of the left ventricle? Which artery supplies the lateral wall of the LV?
66
Which ECG leads look at the interventricular septum? Which artery supplies the septal region?
V1, V2 LAD
67
Which ECG leads look at the anterior wall of the heart? Which part of the heart does this represent? Which coronary artery supplies this region?
V3, V4 anterior wall LAD
68
Each QRS complex is preceded by a P wave, and the rhythm is regular at 70 bpm. What does this indicate?
69
If the PR interval measures 0.24 seconds, how should this be interpreted?
PR interval >0.20 indicates delayed AV nodal conduction = first degree heart block
70
If the QRS is positive in lead I, and aVF, what is the QRS axis?
normal axis
71
The ST segment is elevated in leads II, III, and aVF. What is the most likely diagnosis?
72
A 72-year-old woman presents with palpitations and mild breathlessness. An ECG is recorded. What does the QRS complex represent?
ventricular depolarisation
73
irregular
74
What arrhythmia is this? Why is the PR interval not measurable in this case?
AF with fast ventricular response no distinct P waves in AF - atrial activity is chaotic
75
The QRS complexes are narrow (<120 ms). What does this indicate?
76
Why might AF predispose to stroke?
77
Which structures normally prevents chaotic atrial activity from conducting directly to the ventricles?
78
What scoring system is commonly used to determine stroke risk in Atrial Fibrillation?
79
If this patient had a history of mitral stenosis and developed Atrial Fibrillation, why is anticoagulation especially important?
80
120 bpm - tachy
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What does left axis deviation suggest?
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89
What mechanical complications are patients at risk of within the first week post-MI?
Med Term 3
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