Bradycardia Flashcards

1
Q

Bradycardia - Narrow Complex - Regular Rhythm - 4 types

A
  1. Sinus Brady
  2. A flutter with AV Block
  3. Atrial Tach with AV Block
  4. Junctional Escape Rhythm
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2
Q

Bradycardia - Narrow Complex - Irregular Rhythm - 7 Types

A
  1. Sinus Arrhythmia
  2. Sinus Arrest
  3. A fib with Slow Ventricular Rate
  4. A Flutter with Variable AV Block and Slow Ventricular Rate
  5. Atrial Tach with variable AV Block and Slow Ventricular Rate
  6. Mobitz Type I (Wenckebach)
  7. Mobitz Type II, Second Degree AVB
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3
Q

Bradycardia - Wide Complex - Regular Rhythm - 2 types

A
  1. Regular Supraventricular Rhythm with Wide QRS

2. Ventricular Escape Rhythm

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4
Q

Bradycardia - Wide Complex - Irregular Rhythm - 2 Types

A
  1. Irregular Supraventricular Rhythm with wide QRS

2. Mobitz Type II, Second degree AVB

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5
Q

What artery supplies SA node?

A
  • Proximal RCA in 65%
  • Circumflex in 25%
  • Both in 10%
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6
Q

What artery supplies AV node?

A
  • Proximal RCA in 80%
  • Circumflex in 10%
  • Both in 10%
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7
Q

What is the average drop in heart rate during sleep in young & elderly patients?

A
  • 24 beats in young

- 14 beats in elderly

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8
Q

What are the two categories of Bradycardia?

A

Narrow-complex and Wide-complex (>120msec)

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9
Q

How many msec are each small box at 25 mm/s?

A

40ms

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10
Q

What are the two electrocardiographic subcategories of narrow-complex bradycardia?

A

Regular rhythm and Irregular rhythm

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11
Q

What rhythm: atrial rhythm, HR>100, p-wave before every QRS, inverted t waves in inferior leads (Lead II)?

A

Atrial Tachycardia

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12
Q

Causes of Sinus Bradycardia: Intrinsic SA node dysfunction

A
  1. Idiopathic degeneration (aging)
    1. Ischemia
    2. Infiltrative disorder (amyloidosis)
    3. Infections (Chagas disease)
    4. Collagen Vascular Disease (SLE)
    5. Myotonic dystrophy
    6. Surgical trauma (Valve replacement)
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13
Q

Causes of Sinus Bradycardia: Conditions extrinsic to SA node:

A
  1. Medications (BB)
    1. Electrolyte disturbance (hypokalemia)
    2. Neurally-mediated reflexes (carotid sinus hypersensitivity)
    3. Hypothyroidism
    4. Hypothermia
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14
Q

Medications causing Sinus Bradycardia:

A
  • BB
  • CCB
  • Digoxin
  • Clonidine
  • Antiarrhythymics (amiodarone)
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15
Q

What infections cause pulse-temperature dissociation?

-normally for each degree F, there’s 10 bpm HR increase

A
  1. Legionella
  2. Psitaccosis
  3. Q fever
  4. Typhoid fever
  5. typhus
  6. Babesiosis
  7. Malaria
  8. Leptospirosis
  9. Yellow Fever
  10. Dengue Fever
  11. Viral hemorrhagic fevers
  12. Rocky Mountain Spotted Fever
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16
Q

In A Flutter (assuming 300bpm), what block leads to bradycardia (<60bpm)?

A

300/5=60, therefore < 5:1 block.

17
Q

What is Atrial Tachycardia?

A

Atrial rhythm, > 100bpm, not originating in sinus node (Sinus rhythm has identical morphology p wave, upright in I, aVF).

18
Q

What’s the rate for junctional escape rhythm?

A

40-60 bpm.
-Note: if junctional escape rhythms originate more distally in conduction system (fascicles for distal Purkinjie fibers) then they can have wide QRS morphology and slower rates.

19
Q

Sinus node intermittently stops firing:

A

sinus arrest (a type of sinus pause, impulse generation failure in SA node)

20
Q

Sinus node fires, but are intermittently blocked from depolarizing the atria:

A

Sinoatrial (SA) node exit block

21
Q

No p waves, bradycardia.

A

A Fib with slow ventricular rate

22
Q

Commonly from right atrium, sawtooth pattern.

A

A Flutter

23
Q
Narrow-complex bradycardia, Irregular rhythm.
P wave rate 120 bpm.
Every QRS preceded by a p wave.
Not every p wave followed by a QRS.
P waves inverted in II, III, aVF.
A

Atrial tachycardia with variable AV block and slow ventricular rate.

24
Q

Intermittently dropped QRS complexes:

A

2nd Degree AV blocks: both Mobitz I (Wenckebach) and Mobitz II.

25
Q

What is sinus arrhythmia?

A

The normal reflex-mediated variability in HR during respiratory cycle where HR faster during inspiration and slower during expiration. Enhances gas exchange and VQ matching.

26
Q

What is sinus arrest?

A

The intermittent failure of sinus node to generate an impulse (generator failure). The duration of the pause is unrelated to the basic underlying rate, which differentiates it from 2nd-degree SA exit block (where the rate is a multiple of the basic underlying sinus rate). Longer than 3 seconds requires assessment for sis and may require pacemaker.

27
Q

What is Sinoatrial exit block?

A

The delay or failure of sinus node impulses to propagate through SA node to neighboring atrial tissue (transmission failure).
-1st degree: can’t be detected on EKG.
-2nd degrees: periodically drop the p wave
Type I (Wenckebach): dropped p wave, followed by progressively shortening P-P intervals
Type II: the duration of the pauses is a multiple of the P-P interval, basic underlying rhythm.
-3rd degree: Complete failure of SA node to have impulses leaving nodal region.

Regardless of subtype, if sis, then pacemaker.

28
Q

What causes slow ventricular rate in a fib?

A
  • medications (BB, CCB, dig, amio)
  • conduction system dz (AV block)
  • increased vagal tone (athletes)
29
Q

In a flutter (assuming atrial rate 300 bpm), what’s the ventricular rates with the following blocks: 2:1, 3:1, 4:1, 5:1

A

-300, 150, 100, 75, 60.

30
Q

What’s the prognosis with atrial tachycardia?

A

Usually benign course. Most common in patients without heart disease.

31
Q

How often is second-degree AV block, Mobitz II associated with wide QRS complex?

A

80% have wide QRS

20% have narrow QRS

32
Q

What are the two types of EKG subcategories of wide-complex bradycardia?

A

Regular and Irregular rhythm

33
Q

What are the types of Bradycardia - Wide-complex - Regular rhythms?

A
  1. Regular supraventricular rhythm with wide QRS and slow ventricular rate
  2. Ventricular escape rhythm
34
Q

How do you distinguish on EKG between sinus bradycardia with BBB from a ventricular escape rhythm?

A
  • If AV association: (all QRS complexes preceded by p waves, and all p waves followed by QRS complexes in regular intervals) then sinus brady with BBB.
  • If AV dissociations, then ventricular escape rhythm.
35
Q

What is the rate for ventricular escape rhythm?

A

20-40 bpm.

36
Q

What causes bradycardia - wide complex - irregular rhythm?

A
  1. Irregular supraventricular rhythm with wide QRS complex and slow ventricular rate
  2. Second-degree AV Block, Mobitz type II
37
Q

Why is Mobitz II second-degree AV Block associated with wide QRS complex?

A

Mobitz II, second-degree AV block usually have preexisting BBB (causing baseline wide QRS complex), and the nonconductor beats occur with intermittent failure of the remaining bundle branch.

38
Q

What are some clinical scenarios that results in relative bradycardia in pacemaker-dependent patients?

A

To keep up with metabolic demand, the heart rate on the pacemaker may need to be increased from it’s programmed “lower rate limit” during:

  • sepsis
  • anemia
  • hypoxemia
  • low cardiac output