Ex2 Abnormalities of Cardiac Conduction Flashcards
(97 cards)
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
2
Q
Intrinsic pacemaker of heart
A
SA node
3
Q
Blood supply of SA Node
A
60% - RCA
40% - LCircumflex CA
4
Q
p wave represents
A
SA node impulse spreading rapidly thru atria causing contraction
5
Q
Blood supply of AV Node
A
90% RCA
10% L circumflex
6
Q
High risk Surgery (MI)
A
Major vascular, peripheral vascular surgery (>5%)
7
Q
Intermediate risk surgery (MI)
A
Intraperitoneal, intrathoracic, head/neck, prostate, CEA
1-5%
8
Q
Low risk surgery (MI)
A
cataract, breast, endoscopic: < 1%
9
Q
AV Node - main fxn
A
slows down electrical impulse, prevents overstimulation of ventricles
*long refractory period
10
Q
PR interval represents
A
Conduction thru bundle of His
11
Q
R vs. LBB
A
RBB > LBB
higher risk of damage if MI
(LBB branches earlier, LPF=blood supply from PDA)
12
Q
conduction terminates in
A
His-Purkinje System
13
Q
PR interval
A
120-200 ms
14
Q
QRS complex
A
< 110 ms
15
Q
QT Interval
A
< 440 ms in men
< 460 ms in women
16
Q
ERP
A
Effective refractory period: QRS/Phase I
no matter how strong stimulus, no cardiac impulse will result
17
Q
RRP
A
Relative Refractory period: a strong stimulus can initiate an action potential (another beat, R on T)
18
Q
Prolonged QTc - concern?
A
QTc > 500 ms
Increased risk of TdP
19
Q
Causes of cardiac conduction disturbances
A
Acute MI, myocarditis, rheumatic fever, mononucleosis**, Lyme disease, infiltrative disease (amyloidosis, sarcoidosis)
20
Q
1st degree HB
A
delayed impulse thru AV node
PR interval > 200 ms
Each p wave has corresponding QRS
21
Q
Causes of 1st degree HB
A
normal aging, myocardial ischemia, inferior wall MI, drugs
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
23
Q
2nd Degree HB Type I
A
Wenckebach
progressive prolongation of PR until QRS drops
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
25
2nd degree HB Type II
Progressive prolongation of PRI until QRS drops
- higher risk to progress to complete HB
- s/s syncope/palpitations
26
2nd degree HB Type II Management
Cardiac Pacing
- trancutaneous/transvenous pacing until permanent pacemaker
- NO atropine
- isoproterenol gtt (chemical pacemaker) until pacemaker placed
27
Complete Heart Block
Significant dysrhythmia
| No conduction from atria to ventricles
28
most common cause of complete heart block
Lenegre's Dx: fibrotic degeneration of distal conduction system assoc'd w/ aging
29
Complete Heart Block: rhythm seen
activity of ventricles d/t ectopic pacemaker distal to block
30
Complete heart block: 45-55 bpm
conduction block is near AV node
| QRS narrow
31
Complete heart block: 30-40 bpm
conduction block is below AV node (infranodal)
| QRS wide
32
s/s complete heart block
vertigo, syncope ("Stokes-Adams attack")
| CHF (weakness+dyspnea)
33
3rd degree heart block in anesthesia is d/t
cardiac ischemia, metabolic/electrolyte abnormalities, infection/inflammation near conduction system, reperfusion injury, stunned myocardium after cardiac surgery
34
Tx: complete heart block
transQ/venous pacing or "chemical" pacing (isoproterenol gtt)
35
Pt has complete heart block + arrives for PPM, what must be done before anesthesia?
Transcutaneous/transvenous pacing
36
Pt arrives with complete heart block. Surgeon would like to move forward.
Do NOT operate on this patient - even if found pre-op
37
bundle branch blocks are due to
conduction disturbance at any level of His-Purkinje System
| -blood supply LAD
38
RBBB - seen on ECG
bunny ears V1, V3
| QRS > 120ms
39
LBBB on ECG
QRS > 120 mS
leads 1, V5, V6 - absence of q waves, monomorphic R wave
S and T waves opposite direction of QRS
40
Which is worse: L or R bbb?
LBBB = sicker patient ("redundant blood supply")
| *often an indication of serious heart dx
41
LBBB while under anesthesia
may be sign of MI
42
Sinus Dysrhythmia
Normal, asymptomatic
Normal PR, QRS, ST, rate 60-100
*Irregular R-R interval*
d/t Bainbridge reflex
43
Bainbridge reflex
accelerates HR when intrathoracic pressure is increased during inspiration
slows HR when intrathoracic pressure decreases during expiration
44
Mechanisms of tachydysrhythmias
1. automaticity
2. reentry pathway dysrhythmias
3. Afterdepolarization
45
Automaticity is affected by ____ in tachydysrhythmias
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
sinus tachycardia tx
treat underlying cause (pain, fever, hypotension, hypoxemia)
47
PAC tx
avoid excessive stimulation
| *IF symptomatic/excessive: CCB or BB
48
PSVT
HR 160-220
Most common reason: AVNRT
Common - pediatrics
49
PSVT Tx
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
Inherited disorder r/t PSVT
Wolf-Parkinson White Syndrome
51
WPW: Trigger for SVT
PAC
52
Tx: WPW SVT
Narrow (orthodromic)
-vagal, adenosine, verapamil, BB, amio
Wide complex (antidromic)
-procanamide
53
Most common sustained dysrhythmia
Afib
54
Risk factors for AFib
valv heart dx, long standing lung dx (copd), hyperthyroidism, HTN, OSA
*rx induced: cocaine, ephedra, methamphet, albuterol, ETOH, theophylline
55
Pre-op new onset AFib, continue?
in resolved + in NSR =continue
if < 48h, cardiovert then proceed
-control ventricular rate
56
Rx helpful in new-onset Afib
Beta Blockers
57
Paroxysmal Afib
returns to NSR within 24-48h spontaneously
58
intra-op new onset Afib, what to do?
HD unstable: synchronized cardioversion 100-200J (biphasic)
HD stable: BB or CCB
Amio or procainamide
59
Chronic AFib - tx
anticoagulants
| coumadin, pradaxa, xarelto, eliquis, plavix
60
Afib - Chronic - increased risk for
LA - stasis of blood =
5x risk of embolic stroke
3x risk HF
2x risk dementia/death
61
Chronic Afib - preop tx
- Coumadin to Heparin IV or LMWH 3-7d preop
| - TEE to determine if thrombus present in LAA
62
Pradaxa reversal
Idarucizumab
63
Prevalence of AFib
1/3 pts with AF are >80y/o
| 10% of pts > 80 y/o have AF
64
Chronic Afib - cardioversion, risks?
Clot
| *make sure to perform echo to make sure no clot
65
Emergent case on Chronic Afib + Coumadin
Vitamin K + FFP
66
Chronic Afib - resistant to cardioversion
Catheter Ablation
67
Catheter ablation for Afib - anesthetic considerations
GETA - higher success rate than MAC
68
Risk of catheter ablation for AFib
Damage to phrenic nerve
69
Supraventricular tachycardia most commonly occurs due to a reentry circuit consisting of
anterograde conduction over the slower AV nodal pathway and retrograde conduction over a faster accessory pathway
70
Which of the following precautions should be taken in the patient with Wolff-Parkinson-White syndrome about to undergo anesthesia?
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
A premature beat on the electrocardiogram that exhibits an abnormally wide QRS complex is known as a
premature ventricular contraction
72
The QRS complex of the electrocardiogram indicates that ________________ has occurred.
RV and LV depolarization has occurred.
73
associated with supraventricular tachycardia?
syncope
| polyuria
74
Testing for ablation success- Rx involved
Adenosine: stops conduction thru AV
| isuprel-beta1/2: increases contractility - favors dysrhythmias
75
Removal of catheter during ablation therapy
hold pressure at insertion site
76
LA appendage closure devices
occlusive: Watchman/amulet - require GA, post op anticoag forever
suture: Lariat - require MAC, no anticoags
77
Atrial Flutter characterized by
organized atrial rhythm, atrial rate: 250-350 bpm
Varying degree of AV block (most often 2:1)
p wave "sawtooth"
78
atrial flutter is associated with
ETOH intox, Pulm dx, acute MI
79
hemodynamically unstable a-flutter
cardioversion 50J monophasic
80
A-flutter: ventricular rate control
Amiodarone, cardizem, verapamil
81
Surgery for A-flutter - postpone, proceed, cancel?
Postpone if possible
| Proceed if needed
82
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
Afib
83
Vtach
3+ PVCs in a row
84
Most common cause of sudden cardiac death
VFib
85
grossly irregular ventricular rhythm, variable QRS, incompatible with life
Vfib
86
Long term tx - Vfib
implantable AICD +/- adjuvant Rx therapy
87
Most important factor in tx of Vfib
early defibrillation
| *w/in 3-5min of cardiac arrest
88
SA node not working, HR?
AV junction: 40-60 bpm
89
SA + AV node not working, HR?
cells below AV node fire at 30-45 bpm
90
Sinus bradycardia - tx
```
only if symptomatic --
Transcutaneous/transvenous pacing
Atropine (> 0.5 mg)
Treat etiology
AVOID vagal stimulation
```
91
junctional rhythm
40-60bpm
| No p waves, or upside down p waves
92
junctional rhythm is often
an escape rhythm d/t depressed SA node fxn, SA node block, delayed conduction in AV node
93
junctional rhythm tx
Only if symptomatic (MI, HF, HoTN)
| -atropine .5mg q3-5min, max 3g
94
Pacer: Letter 1
```
Chamber paced (A, V, D)
D=dual
```
95
Pacer: Letter 2
Chamber being sensed/detected
| 0, A, V, D
96
Pacer Letter 3
```
Response to sensed signals
(0, I, T, D)
I - Inhibition
T- Triggering
D both
```
97
three most common pacemaker codes
AAI, VVI, DDD
