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FICM > Diagnostics > Flashcards

Diagnostics Flashcards

1
Q

What is the PR interval and what does it reflect?

A
  • It’s the time imterval from the start of the p wave to the start of the QRS complex
  • It reflects conduction through the AV node
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2
Q

What is the normal duration for the PR interval?

A

120-200ms

or 3-5 small squares

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3
Q

What ECG change is consistent with 1st degree heart block?

A

PR interval > 200ms

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4
Q

What does a PR interval or < 120ms suggest?

A

Pre-excitation (i.e. the presence of an accessory pathway between the atria and ventricles.
or AV nodal (junctional) rhythm

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5
Q

What is second degree heart block, mobitz type 1?

A

Successive prolongation of the PR interval until a QRS complex is dropped
Also called Wenckebach phenomenon

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6
Q

What are pre-excitation syndromes?

A

e.g. WPW and Lown-Ganong-Levine (LGL)
An accessory pathway connects the atria and ventricles
The accessory pathway conducts impulses faster than normal
It may also act an a re-entry circuit, predisposing the individual to re-entrant tachyarrhythmias

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7
Q

What are the characteristic ECG features of WPW syndrome?

A

Short PR interval
Widened QRS
Slurred upstroke to the QRS complex - the delta wave

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8
Q

What are the ECG features of Lown-Ganong-Levine syndrome?

A

Very short PR interval

Normal P waves and QRS waves and no delta waves

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9
Q

What are the ECG features of an AV nodal rhythm?

A

They are narrow complex regular rhythms arising from the AVN

P waves are either absent of abnormal (possibly inverted) with a short PR interval (=retrograde p waves)

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10
Q

What is a Q wave?

A

Any negative deflection that precedes an R wave

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11
Q

What does the Q wave represent?

A

The normal left to right depolarisation of the IV septum

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12
Q

Describe normal Q waves

A
  • Small Q waves are typically seen in left sided leads (I, aVL, V5, V6)
  • Small Q waves are normal in most leads
  • Deeper Q waves (>2mm) may be seen in aVR and III
  • Not normally seen in V1-3
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13
Q

When are Q waves considered pathological?

A
  • > 40ms wide (1mm)
  • > 2mm deep
  • > 25% depth of the QRS complex
  • Seen in leads V1-V3
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14
Q

What is the differential diagnosis of pathological Q waves?

A

Myocardial infarction
Cardiomyopathy
Extreme rotation of the heart
Lead placement errors

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15
Q

Is absence of Q waves in V5-6 considered normal?

A
  • No

- Normally absent in LBBB

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16
Q

What is the R wave?

A

First upward deflection after the P wave

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17
Q

What does the R wave represent?

A

Early ventricular depolarisation

18
Q

What are the 3 key R wave abnormalities?

A

Dominant R wave in V1
Dominant R wave in aVR
Poor R wave progression

19
Q

What is the differential diagnosis of a dominant R wave in V1?

A
  • Normal in children and young adults
  • RVH - PE, persistant infantile patern, L-R shunt
  • RBBB
  • Post MI
  • Incorrect lead placement (V1-3 switched)
  • Dextrocardia
  • Hypertrophic cardiomyopathy
  • Dystrophy
20
Q

What is the differential diagnosis of a dominant R wave in aVR?

A
  • Sodium-channel blocking drugs poisoning e.g. TCA overdose
  • Dextrocardia
  • Incorrect lead placement
  • VT
21
Q

What is poor R wave progression?

A

R wave < 3mm in V3

22
Q

What causes poor R waves progression?

A 
Prior anteroseptal MI
LVH
Inaccurate lead placement
May be normal
Absent R wave progression is characteristically seen in dextrocardia
23
Q

What is the normal QRS width?

A

70-100ms

24
Q

Where do narrow QRS complexes originate from?

A

Supraventricular

  • which could be sinus node (normal p wave)
  • atria (abnormal p wave e.g. AF, flutter)
  • AVN - absent or abnormal p wave with PR < 120ms
25
Q

Where do broad QRS complexes originate from?

A

Either ventricular
or
Supraventricular with abberant conduction e.g. BBB, hyperkalaemia or sodium channel blockade

26
Q

What causes aberrant conduction of QRS complexes?

A 
BBB
Hyperkalaemia
Sodium channel blockade
Ventricular pacing
Hypothermia
WPW
27
Q

How wide does the QRS complex have to be to diagnose BBB?

A

> 120ms

28
Q

What ECG changes are characteristic of RBBB?

A

RSR’ pattern in V1
Deep slurred S waves in the lateral leads
Widened QRS

29
Q

What ECG changes are characteristic of LBBB?

A

Dominant S in V1
Broad notched R waves and absent Q waves in lateral leads
Widened QRS

30
Q

What does high voltage QRS morphology mean?

A

Usually taken in infer LVH

May be normal in patients < 45 esp if slim and athletic

31
Q

Describe the voltage criteria for LVH

A

Multiple voltage criteria exist
Most common are the Skolov-Lyon criteria
S wave in V1 and tallest R wave V5/6 > 35mm
Voltage criteria must be accompanied by non-voltage criteria to be diagnostic of LVH

32
Q

What is the criteria for low-voltage QRS morphology?

A

< 5mm in all limb leads

< 10mm in all precordial leads

33
Q

What is electrical alternans?

A

Alternating height of the QRS complex

Can be due to a massive pericardial effusion

34
Q

What is Wellens syndrome?

A

Biphasic T wave changes in V2-3

Indicate reperfusion of LAD territory

35
Q

What ECG changes are consistent with severe hypokalaemia?

A

Widespread ST depression/T wave inversion
Prominent Q waves
Long QU interval (> 500ms)

36
Q

Which ECG leads does inferior ischaemia affect and which artery is implicated?

A

RCA

II, III, aVF

37
Q

Which ECG leads does lateral ischaemia affect and which artery is implicated?

A

Circumflex or diagonal

I, aVL +/-V6

38
Q

Which ECG leads does posterior ischaemia affect and which artery is implicated?

A

RCA or circumflex artery

R wave in V1-2 with ST depression

39
Q

Which ECG leads does anterior ischaemia affect and which artery is implicated?

A

I, aVL, V2-5

Left anterior descending

40
Q

Which ECG leads does anteroseptal ischaemia show up in?

A

V2-4

41
Q

Which ECG leads does anterolater ischaemia show up in?

A

V3-5

42
Q

Which ECG leads does apical ischaemia show up in and which artery is involved?

A

Left anterior descending artery

II, III, aVF, V5-6

FICM (11 decks)

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