eLFH - The Electrocardiogram Part 2 Flashcards

1
Q

Types of Heart Block

A

1st Degree Heart Block

2nd Degree Heart Block - Mobitz Type 1 (Wenckebach)

2nd Degree Heart Block - Mobitz Type 2

3rd Degree Heart Block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

1st degree heart block definition

A

Prolongation of PR interval

Delay at the AV node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

2nd degree heart block - Mobitz type 1 definition

A

Progressive prolongation of PR interval until P wave is not conducted to ventricles and process restarts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

2nd degree heart block - Mobitz type 2 definition

A

Intermittent failed conduction via AV node from atria to ventricles

Commonly 2:1 or 3:1 block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3rd degree heart block definition

A

Complete dissociation of atrial and ventricular activity

Aka complete heart block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Components of Left Bundle branch

A

Anterior fascicle

Posterior fascicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Causes of LBBB

A

IHD

LVH - HTN, AS

Cardiomyopathy

Pacing of right ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Causes of RBBB

A

IHD

HTN

Cardiomyopathy

RV strain - PE, COPD, ASD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

ECG changes in LBBB

A

Broadened QRS

V1 negative at end of QRS

V6 positive at end of QRS

‘WiLLiaM’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Reason for ECG changes in LBBB

A

Normal left bundle branch conduction is blocked

Septum and left ventricle reliant on depolarisation spreading from right ventricle

Septum still depolarises first but now from right to left - initial V1 small downstroke, V6 small upstroke

Then right ventricle depolarises which may be hidden by ongoing septal depolarisation - V1 small upstroke, V6 small downstroke

Lastly left ventricle depolarises making biggest contribution to QRS as it is largest - V1 large upstroke, V6 large downstroke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

ECG changes in RBBB

A

Broadened QRS

V1 positive and end of QRS

V6 negative at end of QRS

‘MaRRoW’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Reason for ECG changes in RBBB

A

No longer conduction down right bundle branch

Septum depolarises left to right - initial V1 small upstroke, V6 small downstroke

Then left ventricle depolarises normally - V1 large downstroke, V6 large upstroke

Right ventricle conduction delayed and spreads from LV - V1 large upstroke, V6 large downstroke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Left anterior hemiblock definition

A

Block of anterior fascicle of left bundle branch

More common than left posterior hemiblock as coronary blood supply more vulnerable to anterior fascicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

ECG changes with left anterior hemiblock

A

Left axis deviation in otherwise normal ECG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Left posterior hemiblock definition

A

Block of posterior fascicle of left bundle branch

Uncommon and less clinically significant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Bifasicular block definition

A

RBBB + Left fascicular hemiblock (usually anterior)

17
Q

Bifasicular block ECG changes

A

RBBB
Left axis deviation

18
Q

Trifasicular block definition

A

Bifasicular block + 1st degree heart block

19
Q

Trifasicular block ECG changes

A

RBBB
Left axis deviation
Prolonged PR interval

20
Q

Trifasicular block importance

A

Risk of developing complete heart block

21
Q

Indications for pacemaker insertion

A

3rd degree heart block

2nd degree HB Mobitz Type 2

2nd degree HB with symptoms

Bifasicular or Trifasicular block with intermittent 3rd degree or 2nd degree Mobitz type II

Sinus node dysfunction with symptomatic bradycardia and significant pauses

22
Q

Pacemaker categories

A

External or Transvenous

Temporary or Permanent

23
Q

Pacing lead placement

A

Usually either RA and/or RV

Biventricular pacemakers inserted for cardiac resynchronisation therapy - LV paced via coronary sinus

24
Q

ECG findings in Atrial pacing vs Ventricular pacing vs Dual chamber pacing

A

Atrial pacing - pacing spike directly precedes P waves

Ventricular pacing - pacing spike directly precedes QRS (QRS similar to RBBB appearance as RV is being paced)

Dual pacing - pacing spike directly precedes both P wave and QRS

25
Coronary blood supply to AV node
Right coronary artery Therefore inferior MI can cause complete heart block
26
Drug to avoid in SVT with WPW
Digoxin as it acts to block AV node, therefore faster atrial rate would be transmitted directly to ventricles via accessory pathway Results in VT