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Cardiology > ECG Basics > Flashcards

ECG Basics Flashcards

1
Q

Normal QRS duration?

A

100ms

<2.5 small squares

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2
Q

Duration of small and large squares:

A

1 small square = 0.04 secs = 40 millisecs

1 large square = 0.2secs = 200 millisecs

5 large squares = 1 second

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3
Q

Normal PR interval?

A

3 to 5 small squares = 0.12 - 0.2 secs = 120 - 200 millisecs

If <3 small, preexcitation
If >3, AV block

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4
Q

Normal QT interval?

A

Men < 440 ms
Women < 460 ms

Short = < 350 ms

> 500ms = torsades risk

Corrected is when CALCULATED for a HR of 60 (allows serial comparison at different HRs).

Rule of thumb: QT should be less than half the preceding RR

  • start of Q to END of T
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5
Q

Abnormal P wave, and causes:

A

Normal = < 120 ms/ 3 small squares

If SHORT and PEAKED = P PULMONALE =
R atrial enlargement

If WIDE and BIFUD = P MITRALE =
L atrial enlargement

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6
Q

4 features of abnormal Q waves:

A

> 1mm wide
2mm deep

> 25% QRS

Seen leads V1 - V3

Current, or old, MI
(or HOCM)

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7
Q

Normal T waves:

A

Upright in all EXCEPT V1 and aVR
< 5mm tall in limb leads
<10mm tall in praecordial leads

*upright T in V1/aVR is TWI equivalent

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8
Q

Differential for TWI:

A

Ischaemia (incl. Wellens)
RBBB/ LBBB
Raised ICP
PE (S1Q3T3)
Strain patterns (RVH, LVH)
Persistent juvenile or paediatric (v1-3)

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9
Q

‘Extra’ waves, and causes:

A

U wave
- Bradycardia, HypoK
(Hypothermia, Digoxin)

J/ Osborne wave
- Hypothermia <30 deg
(HyperCa, ICP)

Delta wave
- WPW (pathognomic)

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10
Q

Differential for ST elevation:

A

Acute ischaemia
Pericarditis (saddleback)
Takotsubo
LV aneurysm

HOCM
Brugada

BER (praecordial, j point notch, <50)
LBBB
Ventricular pacing

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11
Q

Differential for ST depression:

A

Ischaemia (NSTEMI, reciprocal)
Digoxin
HypoK

RBBB
LBBB
Strain patterns: RVH/ LVH

Ventricular pacing

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12
Q

What is ‘strain’ pattern?

A

Indicates a ventricle under stress- chronically or acutely.
- ST depression
- TW inversion

Adverse prognostic factor

Usually chronic, and will see along with LVH/ RVH.

Acute RV strain in PE.

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13
Q

Calculating corrected QT:

A

Corrects to a HR of 60
Allows comparison over time/ varying HRs
Multiple formulas

BAZZETTS- easiest, but OVERcorrects in a tachy, UNDERcorrects in a brady.

FIDERICIA most accurate ++ outside of standard HR 60-100

BAZ: QTC = QT (ms) / square root of RR (sec)

FID: same but cubed root.

*QT is start of Q to END of T
** Use max slope method

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14
Q

Criteria for LVH on ECG:

A

VOLTAGE:
- S wave V1 plus R wave V5/6 = >7 large
- R in aVL > 11mm

NON VOLTAGE
- LV strain
- Prolonged R wave peak time V6

Need voltage + non voltage for diagnosis.

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15
Q

Causes of long QT:

A

HYPOeverything:
- Thermia
- K
- Ca
- Mg

Ischaemia
Post-ROSC
Post DCR

Congenital long QT

Drugs:

  • Antipsychotics
  • Antidepressants
  • Amiodarone
  • Na channel blockers
  • Antihistamines
  • Macrolides
  • Antimalarials (quinine)
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16
Q

Causes of short QT:

A

HYPERCa
Digoxin
Congenital short QT (non variable with HR)

17
Q

QRS interpretation- normal, abnormal:

A

< 2.5 small squares (100ms)

BROAD=
supraventricular with abherancy
Preexcitation
BBB
HyperK
HypoT
Na channel blockade

ventricular
Ventricular rhythm
Ventricular pacing

SPECIFIC MORPHOLOGY:

18
Q

Calculating axis:

A

‘Quadrant method’

I and aVF

If LAD possible, look at lead II.
—> NEGATIVE = pathological LAD

19
Q

LBBB morphology and causes:

A

Almost always pathological

IHD incl. ANTERIOR MI
—> Sgarbossa
Aortic stenosis
HTN
Dilated cardiomyopathy
Hyperkalaemia
Digoxin

20
Q

LAFB/ LPFB features:

A

LAFB: LAD (I and III: qR, rS)
LPFB: RAD (opposite: I and III: rS, qR)

Skinny

21
Q

Bifasicular block ECG features and significance:

A

LAFB/LPFB (ie. LAD/RAD)
plus
RBBB

Risk of 3 degree heart block (3% at base, 15% if syncope!)

Ie. BF block and syncope = PPM.

22
Q

Trifascicular block ECG features and significance:

A

Bifasicular block (ie. RBBB plus LAD for LAFB/RAD for LPFB)

Plus

Heart block.

If only 1 or 2 degree, same risk as Bifasicular (ie. 4% base, 17% if syncope)

23
Q

RBBB morphology on ECG:

A
  • Broad QRS (>120ms)
  • V1: rsR complex (taller R ear)
    —> followed by TWI (+- STD)
  • V6: Wide ‘W’ S wave

….. then go looking for bi/trifascicular features

Cardiology (14 decks)

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