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Anesthesia & Coexisting Disease > Ex2 Abnormalities of Cardiac Conduction > Flashcards

Ex2 Abnormalities of Cardiac Conduction Flashcards

1
Q

Who should have a baseline ECG?

A

Moderate to High risk surgery in all pts with periop cardiovascular risk:

  • > 65y/o
  • CAD, known
  • HL
  • h/o significant dysrhythmia
  • PAD
  • CVD
  • Significant structural heart dx
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2
Q

Intrinsic pacemaker of heart

A

SA node

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3
Q

Blood supply of SA Node

A

60% - RCA

40% - LCircumflex CA

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4
Q

p wave represents

A

SA node impulse spreading rapidly thru atria causing contraction

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5
Q

Blood supply of AV Node

A

90% RCA

10% L circumflex

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6
Q

High risk Surgery (MI)

A

Major vascular, peripheral vascular surgery (>5%)

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7
Q

Intermediate risk surgery (MI)

A

Intraperitoneal, intrathoracic, head/neck, prostate, CEA

1-5%

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8
Q

Low risk surgery (MI)

A

cataract, breast, endoscopic: < 1%

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9
Q

AV Node - main fxn

A

slows down electrical impulse, prevents overstimulation of ventricles
*long refractory period

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10
Q

PR interval represents

A

Conduction thru bundle of His

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11
Q

R vs. LBB

A

RBB > LBB
higher risk of damage if MI
(LBB branches earlier, LPF=blood supply from PDA)

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12
Q

conduction terminates in

A

His-Purkinje System

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13
Q

PR interval

A

120-200 ms

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14
Q

QRS complex

A

< 110 ms

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15
Q

QT Interval

A

< 440 ms in men

< 460 ms in women

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16
Q

ERP

A

Effective refractory period: QRS/Phase I

no matter how strong stimulus, no cardiac impulse will result

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17
Q

RRP

A

Relative Refractory period: a strong stimulus can initiate an action potential (another beat, R on T)

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18
Q

Prolonged QTc - concern?

A

QTc > 500 ms

Increased risk of TdP

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19
Q

Causes of cardiac conduction disturbances

A

Acute MI, myocarditis, rheumatic fever, mononucleosis**, Lyme disease, infiltrative disease (amyloidosis, sarcoidosis)

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20
Q

1st degree HB

A

delayed impulse thru AV node
PR interval > 200 ms
Each p wave has corresponding QRS

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21
Q

Causes of 1st degree HB

A

normal aging, myocardial ischemia, inferior wall MI, drugs

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22
Q

Tx 1st degree HB

A

Avoid increases in vagal tone
Tx: Atropine 0.5 mg
DO NOT give 0.2 mg (will slow down HR more)
*weigh pros/cons in ischemic heart dx – but if symptomatic: give atropine

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23
Q

2nd Degree HB Type I

A

Wenckebach

progressive prolongation of PR until QRS drops

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24
Q

2nd Degree HB Type I Management

A

Maintain CO

  • usually asymptomatic/does not progress to complete HB
  • if unstable (s/s): 1st tx = atropine, 2nd tx = pace
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25
Q

2nd degree HB Type II

A

Progressive prolongation of PRI until QRS drops

  • higher risk to progress to complete HB
  • s/s syncope/palpitations
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26
Q

2nd degree HB Type II Management

A

Cardiac Pacing

  • trancutaneous/transvenous pacing until permanent pacemaker
  • NO atropine
  • isoproterenol gtt (chemical pacemaker) until pacemaker placed
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27
Q

Complete Heart Block

A

Significant dysrhythmia

No conduction from atria to ventricles

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28
Q

most common cause of complete heart block

A

Lenegre’s Dx: fibrotic degeneration of distal conduction system assoc’d w/ aging

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29
Q

Complete Heart Block: rhythm seen

A

activity of ventricles d/t ectopic pacemaker distal to block

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30
Q

Complete heart block: 45-55 bpm

A

conduction block is near AV node

QRS narrow

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31
Q

Complete heart block: 30-40 bpm

A

conduction block is below AV node (infranodal)

QRS wide

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32
Q

s/s complete heart block

A

vertigo, syncope (“Stokes-Adams attack”)

CHF (weakness+dyspnea)

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33
Q

3rd degree heart block in anesthesia is d/t

A

cardiac ischemia, metabolic/electrolyte abnormalities, infection/inflammation near conduction system, reperfusion injury, stunned myocardium after cardiac surgery

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34
Q

Tx: complete heart block

A

transQ/venous pacing or “chemical” pacing (isoproterenol gtt)

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35
Q

Pt has complete heart block + arrives for PPM, what must be done before anesthesia?

A

Transcutaneous/transvenous pacing

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36
Q

Pt arrives with complete heart block. Surgeon would like to move forward.

A

Do NOT operate on this patient - even if found pre-op

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37
Q

bundle branch blocks are due to

A

conduction disturbance at any level of His-Purkinje System

-blood supply LAD

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38
Q

RBBB - seen on ECG

A

bunny ears V1, V3

QRS > 120ms

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39
Q

LBBB on ECG

A

QRS > 120 mS
leads 1, V5, V6 - absence of q waves, monomorphic R wave
S and T waves opposite direction of QRS

40
Q

Which is worse: L or R bbb?

A

LBBB = sicker patient (“redundant blood supply”)

*often an indication of serious heart dx

41
Q

LBBB while under anesthesia

A

may be sign of MI

42
Q

Sinus Dysrhythmia

A

Normal, asymptomatic
Normal PR, QRS, ST, rate 60-100
Irregular R-R interval
d/t Bainbridge reflex

43
Q

Bainbridge reflex

A

accelerates HR when intrathoracic pressure is increased during inspiration
slows HR when intrathoracic pressure decreases during expiration

44
Q

Mechanisms of tachydysrhythmias

A
  1. automaticity
  2. reentry pathway dysrhythmias
  3. Afterdepolarization
45
Q

Automaticity is affected by ____ in tachydysrhythmias

A

slope of phase 4 depolarization +/- resting membrane potential

  • SNS = increases HR (increased slope phase 4 depol., decreased resting potential)
  • PNS = decreased HR (decreased slope phase 4 depol., increased resting potential)
46
Q

sinus tachycardia tx

A

treat underlying cause (pain, fever, hypotension, hypoxemia)

47
Q

PAC tx

A

avoid excessive stimulation

*IF symptomatic/excessive: CCB or BB

48
Q

PSVT

A

HR 160-220
Most common reason: AVNRT
Common - pediatrics

49
Q

PSVT Tx

A
  1. Vagal maneuvers
  2. Adenosine (6mg/12mg), BB, CCB
  3. if unresponsive/unstable: cardioversion
    * if hx SVT: avoid precipitating events - increased SNS, electrolyte imbalance, acid/base disturbance
50
Q

Inherited disorder r/t PSVT

A

Wolf-Parkinson White Syndrome

51
Q

WPW: Trigger for SVT

A

PAC

52
Q

Tx: WPW SVT

A

Narrow (orthodromic)
-vagal, adenosine, verapamil, BB, amio
Wide complex (antidromic)
-procanamide

53
Q

Most common sustained dysrhythmia

A

Afib

54
Q

Risk factors for AFib

A

valv heart dx, long standing lung dx (copd), hyperthyroidism, HTN, OSA
*rx induced: cocaine, ephedra, methamphet, albuterol, ETOH, theophylline

55
Q

Pre-op new onset AFib, continue?

A

in resolved + in NSR =continue
if < 48h, cardiovert then proceed
-control ventricular rate

56
Q

Rx helpful in new-onset Afib

A

Beta Blockers

57
Q

Paroxysmal Afib

A

returns to NSR within 24-48h spontaneously

58
Q

intra-op new onset Afib, what to do?

A

HD unstable: synchronized cardioversion 100-200J (biphasic)
HD stable: BB or CCB
Amio or procainamide

59
Q

Chronic AFib - tx

A

anticoagulants

coumadin, pradaxa, xarelto, eliquis, plavix

60
Q

Afib - Chronic - increased risk for

A

LA - stasis of blood =
5x risk of embolic stroke
3x risk HF
2x risk dementia/death

61
Q

Chronic Afib - preop tx

A
  • Coumadin to Heparin IV or LMWH 3-7d preop

- TEE to determine if thrombus present in LAA

62
Q

Pradaxa reversal

A

Idarucizumab

63
Q

Prevalence of AFib

A

1/3 pts with AF are >80y/o

10% of pts > 80 y/o have AF

64
Q

Chronic Afib - cardioversion, risks?

A

Clot

*make sure to perform echo to make sure no clot

65
Q

Emergent case on Chronic Afib + Coumadin

A

Vitamin K + FFP

66
Q

Chronic Afib - resistant to cardioversion

A

Catheter Ablation

67
Q

Catheter ablation for Afib - anesthetic considerations

A

GETA - higher success rate than MAC

68
Q

Risk of catheter ablation for AFib

A

Damage to phrenic nerve

69
Q

Supraventricular tachycardia most commonly occurs due to a reentry circuit consisting of

A

anterograde conduction over the slower AV nodal pathway and retrograde conduction over a faster accessory pathway

70
Q

Which of the following precautions should be taken in the patient with Wolff-Parkinson-White syndrome about to undergo anesthesia?

A

Instruct the patient to continue taking antidysrhythmics up to the day of surgery
Avoid hypovolemia
avoid situations that could result in sympathetic outflow such as pain or hypovolemia, avoid verapamil or digoxin (which could enhance anterograde conduction through an accessory pathway) in the treatment of any arising dysrhythmia, and have adenosine, and/or amiodarone available for treatment of tachydysrhythmias.

71
Q

A premature beat on the electrocardiogram that exhibits an abnormally wide QRS complex is known as a

A

premature ventricular contraction

72
Q

The QRS complex of the electrocardiogram indicates that ________________ has occurred.

A

RV and LV depolarization has occurred.

73
Q

associated with supraventricular tachycardia?

A

syncope

polyuria

74
Q

Testing for ablation success- Rx involved

A

Adenosine: stops conduction thru AV

isuprel-beta1/2: increases contractility - favors dysrhythmias

75
Q

Removal of catheter during ablation therapy

A

hold pressure at insertion site

76
Q

LA appendage closure devices

A

occlusive: Watchman/amulet - require GA, post op anticoag forever
suture: Lariat - require MAC, no anticoags

77
Q

Atrial Flutter characterized by

A

organized atrial rhythm, atrial rate: 250-350 bpm
Varying degree of AV block (most often 2:1)
p wave “sawtooth”

78
Q

atrial flutter is associated with

A

ETOH intox, Pulm dx, acute MI

79
Q

hemodynamically unstable a-flutter

A

cardioversion 50J monophasic

80
Q

A-flutter: ventricular rate control

A

Amiodarone, cardizem, verapamil

81
Q

Surgery for A-flutter - postpone, proceed, cancel?

A

Postpone if possible

Proceed if needed

82
Q

An ECG exhibits an irregular ventricle rhythm with narrow QRS complexes and P waves that are unpredictable in both rhythm and shape. These findings are consistent with

A

Afib

83
Q

Vtach

A

3+ PVCs in a row

84
Q

Most common cause of sudden cardiac death

A

VFib

85
Q

grossly irregular ventricular rhythm, variable QRS, incompatible with life

A

Vfib

86
Q

Long term tx - Vfib

A

implantable AICD +/- adjuvant Rx therapy

87
Q

Most important factor in tx of Vfib

A

early defibrillation

*w/in 3-5min of cardiac arrest

88
Q

SA node not working, HR?

A

AV junction: 40-60 bpm

89
Q

SA + AV node not working, HR?

A

cells below AV node fire at 30-45 bpm

90
Q

Sinus bradycardia - tx

A 
only if symptomatic -- 
Transcutaneous/transvenous pacing
Atropine (> 0.5 mg)
Treat etiology
AVOID vagal stimulation
91
Q

junctional rhythm

A

40-60bpm

No p waves, or upside down p waves

92
Q

junctional rhythm is often

A

an escape rhythm d/t depressed SA node fxn, SA node block, delayed conduction in AV node

93
Q

junctional rhythm tx

A

Only if symptomatic (MI, HF, HoTN)

-atropine .5mg q3-5min, max 3g

94
Q

Pacer: Letter 1

A 
Chamber paced (A, V, D)
D=dual
95
Q

Pacer: Letter 2

A

Chamber being sensed/detected

0, A, V, D

96
Q

Pacer Letter 3

A 
Response to sensed signals
(0, I, T, D)
I - Inhibition
T- Triggering
D both
97
Q

three most common pacemaker codes

A

AAI, VVI, DDD

Anesthesia & Coexisting Disease (23 decks)

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