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Flashcards in Week 7 Deck (63)
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1

Which direction is Q wave deflection?

downwards

2

What does the Q wave represent?

septal depolarisation (left to right)

3

Which leads are septal Q waves seen in?

Leads looking at the left side of the heart (I, II, aVL, V5 and V6)

4

What are the 3 characteristics of pathological Q waves

More than 2mV amplitude or 0.04 seconds long

5

What should you consider if you see pathological Q waves?

(1) myocardial infarction, (2) LV hypertrophy, (3) bundle branch block (4) pulmonary embolism (if Q wave in lead III).

6

In many cases do pathological Q waves become permanent following MI?

90%

7

Can myocardial infarctions be asymptomatic?

yes - 20% are silent

8

What are the symptoms of a MI?

chest pain, pain in left arm and jaw, sweating, nausea

9

Is ST segment elevation an ECG characteristic of MI?

Yes

10

Explain how MI leads to pathological Q waves

MI causes necrosis of myocardium which can no longer conduct electrical activity. Leads 'look through' necrotic tissue and since electrical activity moves from the inside to the outside of the heart, a negative deflection is detected.

11

A MI that produces a pathological Q wave is what type of MI?

Transmural

12

Is a subendocardial or transmural MI more serious?

Transmural - damage to all layers of the heart

13

What 4 questions should you ask about QRS complex?

1. are R/S wave too tall? 2. are QRS complex too small? 3. are QRS complex too wide? 4. are QRS abnormal shape?

14

The deepest R and S wave should exceed how many mm?

25mm (2.5 large squares)

15

The R wave increases in height between V1 and V6?

True

16

Is the R wave smaller than the S wave in V1 and V2

True

17

Is the R wave smaller than the S wave in V5 and V6?

False

18

What waves are high/deep in LVH?

Leads that look at the heart from the left (I, II, aVL, V5 and V6) have high R waves and the reciprocal (leads that look at the heart from the right) V1 and V2 have deep S waves

19

What criteria must be met for LVH?

V5/6 R wave > 25mm, V1/2 S wave > 25mm or V5/6 + V1/2 = > 35mm

20

Can young, thin people exceed LVH ECG criteria? Does it mean they have LVH?

Yes - doesn't diagnose LVH - echocardiogram necessary

21

What might cause pathological LVH?

hypertension

22

In what ways is LVH detrimental?

Chamber narrows inwards as well as outwards and reduces chamber size - reducing CO

23

What has to be present for LVH/RVH to be associated with 'strain'?

ST segment depression and T-wave inversion

24

What ECG change does RVH cause?

dominant R wave in V1

25

What is RVH associated with?

(1) right axis deviation, (2) RBBB

26

How is a dominate R wave in V1-V3 associated with WPW?

In a left-sided WPW you typically see right axis deviation and so a dominant R wave as electrical activity flows towards the right side of the heart

27

How is a dominant S wave in V1-V3 associated with WPW?

In right-sided WPW you typically see left axis deviation and so a dominant R wave as electrical activity flows away from the right side of the heart

28

Are dominant R waves seen in posterior wall MI?

Yes - reciprocal appearance in anterior chest leads of typical MI changes - so pathological Q wave is seen as R wave.

29

Reasons for small QRS?

Reduced electrical activity recording: (1) obesity, (2) emphysema, (3) pericardial effusion (excess fluid in pericardial cavity)

30

Minimum length of ventricular depolarisation?

0.12 seconds (3 small boxes)