Week 7

Question 1

Which direction is Q wave deflection?

Answer 1

downwards

Question 2

What does the Q wave represent?

Answer 2

septal depolarisation (left to right)

Question 3

Which leads are septal Q waves seen in?

Answer 3

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

Question 4

What are the 3 characteristics of pathological Q waves

Answer 4

More than 2mV amplitude or 0.04 seconds long

Question 5

What should you consider if you see pathological Q waves?

Answer 5

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

Question 6

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

Answer 6

90%

Question 7

Can myocardial infarctions be asymptomatic?

Answer 7

yes - 20% are silent

Question 8

What are the symptoms of a MI?

Answer 8

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

Question 9

Is ST segment elevation an ECG characteristic of MI?

Answer 9

Yes

Question 10

Explain how MI leads to pathological Q waves

Answer 10

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.

Question 11

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

Answer 11

Transmural

Question 12

Is a subendocardial or transmural MI more serious?

Answer 12

Transmural - damage to all layers of the heart

Question 13

What 4 questions should you ask about QRS complex?

Answer 13

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

Question 14

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

Answer 14

25mm (2.5 large squares)

Question 15

The R wave increases in height between V1 and V6?

Answer 15

True

Question 16

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

Answer 16

True

Question 17

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

Answer 17

False

Question 18

What waves are high/deep in LVH?

Answer 18

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

Question 19

What criteria must be met for LVH?

Answer 19

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

Question 20

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

Answer 20

Yes - doesn’t diagnose LVH - echocardiogram necessary

Question 21

What might cause pathological LVH?

Answer 21

hypertension

Question 22

In what ways is LVH detrimental?

Answer 22

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

Question 23

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

Answer 23

ST segment depression and T-wave inversion

Question 24

What ECG change does RVH cause?

Answer 24

dominant R wave in V1

Question 25

What is RVH associated with?

Answer 25

(1) right axis deviation, (2) RBBB

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

Are dominant R waves seen in posterior wall MI?

Answer 28

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

Question 29

Reasons for small QRS?

Answer 29

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

Question 30

Minimum length of ventricular depolarisation?

Answer 30

0.12 seconds (3 small boxes)

Question 31

What does a wide QRS typically mean?

Answer 31

Conduction through the ventricles was slower than normal

Question 32

What are three causes of wide QRS?

Answer 32

(1) bundle branch block, (2) ventricular ectopic, (3) hyperkalaemia

Question 33

Does a bundle branch block lead to indirect depolarisation by other bundle branches?

Answer 33

Yes

Question 34

What is a hemi-block?

Answer 34

Block of the left anterior fascicle or left posterior fascicle

Question 35

What happens during v. depolarisation with bundle branch block

Answer 35

Ventricles are depolarisation by myocyte-myocyte conduction

Question 36

What leads are used to determine a LBBB or RBBB?

Answer 36

V1 and V6

Question 37

What is the acronym used?

Answer 37

WILLIAM MORROW

Question 38

What is seen in V1 in RBBB?

Answer 38

(1) positive septal R wave, (2) S wave (LV dep), (3) R prime (late RV dep).

Question 39

What is seen in V6 in RBBB?

Answer 39

(1) negative septal Q wave, (2) R wave (LV dep), (3) wide S wave (late RV dep).

Question 40

Is LBBB an EECG contra-indication?

Answer 40

Yes

Question 41

What is LBBB an EECG a contra-indication?

Answer 41

The ECG beyond QRS complex cannot be read

Question 42

What is PVC?

Answer 42

Ectopic beat originating outside the conduction system

Question 43

What is bigemy?

Answer 43

PVC after every 2nd normal QRS

Question 44

What is trigemy?

Answer 44

PVC after every 3rd normal QRS

Question 45

What may cause PVC's?

Answer 45

Anything that disrupts electrolyte balance

Question 46

Why are PVC's important?

Answer 46

(1) they can lead to more serious arrhythmias (2) they decrease CO (particularly if they frequent - reduced ventricular filling)

Question 47

Which direction is the T-wave deflected in premature beat (PVC)?

Answer 47

opposite of QRS complex

Question 48

Are P-wave present in PVC?

Answer 48

Usually absent but retrograde conduction may depolarise the atrial and distort the ST segment

Question 49

Can you measure the PR and QT intervals on premature beat?

Answer 49

No

Question 50

What is the R-on-T phenomena

Answer 50

When a PVC strikes on the downstroke of previous T wave and can trigger more serious rhythm disturbances

Question 51

What is seen after a PVC?

Answer 51

Compensatory pause - time between two normal QRS is doubled

Question 52

A PVC that is not followed by a compensatory pause is referred to as what?

Answer 52

Interpolated

Question 53

Why is a compensatory pause seen?

Answer 53

the ventricular myocardium is in refractory and cannot be depolarised

Question 54

PVC that look alike are what?

Answer 54

Uniform

Question 55

If PVC's are uniform they likely originate from the same ectopic focus? T/F?

Answer 55

True

Question 56

What are two PVC's in a row called?

Answer 56

Couplet

Question 57

Why can two PVC's in a row cause ventricular tachycardia?

Answer 57

Because they meet refractory tissue

Question 58

What is multiform PVC

Answer 58

PVC that look different as they originate from different foci or same sight with different conduction

Question 59

What are dangerous PVC's?

Answer 59

(1) R-on-T PVC, (2) paired, (3) trigemy, (4) bigamy, (5) multiform

Question 60

is the pulse after a PVC stronger or weaker?

Answer 60

Weaker

Question 61

What should you consider if you see a slurred or notched QRS?

Answer 61

(1) WPW, (2) hemi-block (3) incomplete bundle branch block

Question 62

LBBB V1 characteristics

Answer 62

(1) Q wave (septal depolarisation from right to left), (2) R-wave from normal RV dep (3) S wave from late LV dep

Question 63

LBBB V6 characteristics

Answer 63

(1) R wave (septeal depolarisation from right to left) (2) S-wave from normal RV dep (3) R-wave from late LV dep