69. Disryhthmias Flashcards
1
Q
3 ions in action potential
A
K
Na
Ca
2
Q
artery perfusing SA node
A
55% RCA
45% LCA
3
Q
rate of AV node
A
45-60
4
Q
rate of infranodal pacer
A
30-45
5
Q
3 fascicles and their supply
A
RBB – LAD supply
LASB – LAD supply
LPIB – RCA or LCA
6
Q
3 mech of dysrythmias
A
1, enhance automaticity
- trigger actitivty
- re-entry circuits
7
Q
Class 1 ion
A
Na fast
8
Q
Class 1A medication and use
A
Procainamide
- Most common
- Ventricular and supraventricular
- Give until stop rhythm, hypoT or QRS widening
9
Q
Class 1B medication and use
A
- Less slowing than other class 1 agents
- Shorten repolarization
Lidocaine - Only one for emergency
- Suppresses AV and SA node function
10
Q
Class 1C medication and use
A
- Profoundly slow depolarization
- Can also be prodysrtyhmic
Flacainaide - Paroxysmal SVT
- Narrow therapeutic index
Propafenone - Some B and Ca action
- Caution with structural or ischemic heart disease
11
Q
Class 2 mechanism
A
- BB
- Suppress SA node automaticity and slow conduction through AV node
- Good for ventricular rate control
- Can also terminate AV nodal reentrant tachys
- More B1 are more cardio selective
12
Q
Contraindication to BB
A
o Asthma or COPD
o Advanced CHF
o 3rd trimester
o Heart block beyond first degree
13
Q
Class 3 mechanism
A
- Prolong refractory period by blocking K
- Variable QT effects
14
Q
examples of class 3
A
amio
sotalol
15
Q
short and long term SE of amio
A
Short term o Hypotension o Brady o Heart failure Long term - Irrevereisble lung and thyroid disease - photosensitivy - corneal deposits - GI intolerance
16
Q
Class 4 mechanism
A
- Slow Ca channel blockers
- Slow AV conduction and suppress SA node
- All cause peripheral vasodilation
17
Q
2 examples of class 4
A
Diltiazem - Loading IV dose then infusion PRN - Oral dose to sustain the response Verapamil - Rare to give - May cause hypotension
18
Q
SEs of digoxin
A
- GI intolerance
- fatigue
- color distubances
- HA
- psychosis
- ## heart block
19
Q
Best leads to see disrhytmias
A
V1 or inferior
20
Q
aid to unmask dysryhtmias
A
vagal maneuvers
21
Q
Vagal causes of sinus brasy
A
o Ischmia
o Hypoxia
o Cold
o Drugs
22
Q
def sinus dysrhytmia
A
- Conducted p waves with variable P-P interval
- Normal variant
- Common in kids and young adults
23
Q
Tx of sick sinus
A
- Acute
o Treat specific rhythm
o Be wary of profound brady that may need pacing - Long term
24
Q
define 1st degree block
A
- Prolonged conduction
- Long PR
- Can be normal
- No Tx other than avoid nodal blocking agents
25
2 types of 2nd degree block
```
Type 1
o Progressive impairment in AV node
o Lengthen to block
o Generally transient
Type 2
o Block below the AV node
o Sporadic and periodic conduction
o Usually narrow QRS, but can be wide
```
26
def and Tx 3rd degree block
- Complete
- No conduction of atrial impulses
- AV dissociation
- Usually due to degeneration, acute ischemia, drugs
- Any new or symptomatic should be admitted
27
def extrasystoles
- Ectopic atrial or vent focus
- May or may not have contraction
- Can occur in geminy
28
def PACs
- Common and usually no sig
- Abnormal P wave in the ECG
- Usually conducted
o Changes PP interval;
- Blocked PAC can cause non-compensatory pause
- Can lead to SVT
29
things that worsen PVCs
pain, catechoalmines, anxiety, stims
30
ECG pattern of PVCs
- Wide QRS without preceding P wave
- Compensatory pause
- LBBB appearance if from R ventricle
31
Def atrial tachy
- > 100BPM with non-sinus node site
- Abnormal P waves
Multifocal atrial tachy
o 3 or more distinct P waves tyeps
o Pulmonary disease in 60%
o Can be due to primary cardiac patho
32
Tx of atrial tachy
o Correct precipitating factors
o Lytes
o Drugs
o Hypoxemia
33
3 types of Afib
```
o Paroxysmal
o Persistent (requires conversion)
o Permanent (no longer converting)
```
34
usual afib rate
- Ventricular rate rarely above 160—170
| - > 200 usually mean another reentrant pathway
35
Causes of afib
- HTN
- cardiomyopathy
- ACS
- valves
- CHF
- pericarditis
- HyperT
- sick sinus
- contusion
- EtOH
- idiopathic
- cardiac surgery
- catechoamine excess
- PE
- accessory pathway
36
MGMT stable afib
```
Nodal blocking agent to reduce < 120
BB or CCB
Not for accessory pathway
Rhythm vs rate control
Not great evidence for rhythm, often fails
If < 48 hours or anticoag can trial cardioversion
Higher success with electrical
If chemical
• Clas 1A, 1C, and 3 best
• Procainamide and amio most common
```
37
CHADS2VASC
```
CHF
HTN
Age
DM
Stroke
Gender
Age
Valves
```
38
Def. AVNRT
- AKA paroxysmal SVT
- Regular, narrow complex tachy with vent rate of 130 or more, usually more than 160
- Reentry circuit in AV node
- Abrupt onset
o Usually during exercise or stress
39
Tx SVT
```
Tx
o Vagal
o Adenosine
o If refractory: BB or CCB
Can rarely do electrical cardioversion
```
40
Classic rentrant pathway
WPW
41
3 ECG features of WPW
o Short PR < 0.12
o QRS > 0.1
o Slurred upstroke
42
RFs for WPW
```
cardiomyopathy
transpostion of great vessels
MV prolapse
tricuspid atresia
ebsteins
```
43
2 types of re-entrant and their features
```
- Orthodromic
o AV anterograde
o Pathway retrograde
o Narrow QRS and verntricular rate constrained
- Antidromic
o AV node retrograde
o Pathway anterograde
o Wide QRS and very rapid
```
44
Tx of orthodromic
Treat like AVRNT
| Vagal and adenosine
45
Tx of antidromic
Rates can be >200
Nodal blocking agents contraindicated
Procainamide is first line
Electrocardioversion if at all unstable
46
Brugada approach to differentiate VT from SVT with abberancy
If any yes - VT, if all no SVT
1. Absence of RS in all precordial leads
2. R to S interval > 100ms in one precordial
3. AV dissociation
4. Criteria for VT in both precordial leads V1-2 and V6
47
Tx of SVT with abberancy
- If unstable, cardiovert
- If borderline, can trial procainamide or amio
- Possible to use adenosine if careful search does not reveal VT
48
Tx V tach
```
o Stable
Trial amio
Procainamide 2nd line
o Unstable
Cardiovert
```
49
3 criteria for torsades
o Vent rate> 200
o Undulating QRS
o Paroxysms < 90sec
50
Tx of torsades
o Treat underlying causes
o MgSO4
o Cardiovert
51
Acquired causes of long QT and torsades
```
Drugs
- 1A and 1C anti-arrythmics
- haldol
- TCAs
- ABx
- antihistamines
- antiseizures
- antiemetics
Lytes
Diet - starvation
Severe brady
HypoTh
Contrast
CVA
MI
```
52
ECG for brugada
o Downward coved or saddleback STE in V1-3
53
Tx brugada
implantable defib
