AV Blocks Flashcards

1
Q

Types of AVN heart blocks

A

First degree
Second degree type 1
Second degree type 2
Third degree - complete

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2
Q

Rhythm of first degree heart block

A

Regular

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3
Q

PR interval of first degree heart block

A

Prolonged

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4
Q

P wave and QRS complex in first degree heart block

A

Normal

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5
Q

History of patient with first degree heart block

A

Asymptomatic and unremarkable exam

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6
Q

Management of first degree heart block

A

Leave or stop AVN blocking drugs

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7
Q

What is the difference between type 1 and type 2 second degree heart block

A

Type 1 has PR interval which gradually lengthen but type 2 has consistently normal PR interval.

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8
Q

Rhythm of Mobitz type 1

A

Irregular

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9
Q

Rhythm of Mobitz type 2

A

Irregular in 3:1 or 4:1 pattern

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10
Q

P wave and QRS complex in Mobitz type 1

A

QRS complexes are occasionally dropped, not all P waves followed by QRS

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11
Q

P wave and QRS complex in Mobitz type 2

A

More P waves than QRS complexes, intermittently dropped QRS

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12
Q

What does a broad QRS complex tell you in Mobitz type 2

A

Broad rather than normal if conduction abnormality is located distal to bundle of His

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13
Q

History of Mobitz type 1

A

Some can develop symptomatic bradycardia and present with pre-syncope and syncopal episodes

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14
Q

History of Mobitz type 2

A

May have palpitations, pre-syncope and syncope

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15
Q

Examination findings in Mobitz type 2

A

Regularly irregular pulse where there is a pattern of how many atrial depolarisations P waves lead to ventricular depolarisation QRS waves

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16
Q

Examination findings in Mobitz type 1

A

Bradycardia

17
Q

Management of Mobitz type 1

A

AV blocking drugs stopped, pacemaker if symptomatic

18
Q

Management of Mobitz type 2

A

Cardiac monitor, underlying cause investigated, temporary pacing or isoprenaline may be required if the patient is haemodynamically compromised due to bradycardia

19
Q

P wave and PR interval in complete heart block

A

P waves present but not associated with QRS, PR interval absent as no AV dissociation

20
Q

QRS complex in complete heart block

A

Narrow or broad, depending on site of escape rhythm

21
Q

History of patient with complete heart block

A

Palpitations, pre-syncope, syncope, confusion, SOB, chest pain, sudden cardiac death

22
Q

Examination findings of patient with complete heart block

A

Irregular pulse, bradycardia, haemodynamic compronmise

23
Q

Management of complete heart block

A

Cardiac monitor.
Transcutaneous pacing/temp pacing wire or isoprenaline infusion may be required. Some rhythms may respond to atropine.
Permanent pacemaker may be required.

24
Q

Causes of right bundle branch block

A

Atrial septal defect, Brugada syndrome, RV hypertrophy, PE, rheumatic heart disease, myocarditis, cardiomyopathy, HTN

25
Q

Causes of left bundle branch block

A

Aortic stenosis, dilated cardiomyopathy, acute MI, extensive coronary heart disease, primary disease of cardiac electrical conduction system, aortic root dilatation/regurg, lyme disease, side effects of some surgeries

26
Q

ECG changes in right bundle branch block

A

QRS duration <120m/s, RSR pattern (‘M’ shape) in V1-3, wide slurred S wave in I, aVL and V5-V6

27
Q

ECG changes in left bundle branch block

A

QRS duration of <120m/s, dominant S wave in V1, broad monophasic R wave in I, aVL, V5-6, absense of Q waves in I, aVL, V5-6, R wave >60 in V5-6

28
Q

Complications of second degree type 2 heart block

A

Risk of progressing to symptomatic complete AV block and asystole

29
Q

Complications of third degree heart block

A

Sudden cardiac death from ventricular arrhythmias

30
Q

Causes of third degree heart block

A

Structural heart disease, Lev’s and Lenegre’s disease, MI, ischaemic CM, calcific aortic stenosis, dilated CM, amyloidosis, sarcoidosis, surgery, drugs, endocarditis, lyme disease, chagas disease, SLE, RA, thyroid dysfunction

31
Q

Causes of second degree heart block type 2

A

MI, fibrosis of conducting system, surgery, SLE, sclerosis, inflammatory conditions, infiltrative myocardial disease, hyperkalaemia, drugs, thyroid dysfunction,

32
Q

Causes of second degree heart block type 1

A

Increased vagal tone in athletes, drugs, inferior MI, myocarditis, surgery

33
Q

Complications of second degree type 1 heart block

A

May be haemodynamically compromised but this is rare

34
Q

Causes of first degree heart block

A

Enhanced vagal tone in athletes, post-MI, lyme disease, SLE, congenital, myocarditis, electrolyte derrangements, drugs and thyroid dysfunction

35
Q

Complication of first degree heart block

A

Does not usually progress to higher grade, may increase risk of AF