Arrhythmias 1 Flashcards
3 mechanisms of arrhythmia
Abnormal Automaticity
Triggered Activity
Reentry
3 reasons for abnormal automaticity
scar, ischemia, age
examples of abnormal automaticity
SSS, afib, PVCs, PACs
? + Torsades = Long QT
Bradycardia
Bradycardia + Early after depolarizations = ?
Torsades
Bidirectional VT + Dig = ?
Delayed after depolarizations
whereas Long QT is exacerbated by bradycardia, what exacerbate delayed afterdepolarizations?
catecholamines
3 things needed for reentry arrhythmia
2 pathways
slow/fast
unidirectional block in 1 of the pathways
In terms of Sn/Sp, what do NTG and Isoproterenol do in a tilt table test?
Increase Sn
Decrease Sp
HV Interval
normal = 35-55 msec
Autonomic factors little influence
if HV>100ms–> PPM needed (even if asymptomatic)
Is infrahissian block serious?
yes! Can lead to asystole.
Long A-H interval makes you think of?
slow/fast AVNRT
Late potentials on Signal Averaged ECG
Infarct, scar (slow conduction)
Most common reason to get PPM in US?
Sinus node dysfunction
Class I indications for PPM in sinus node Dz
1) SND w/ symptomatic brady
2) SND w/ chronotropic incomp.
3) SND w/ symptomatic brady and required meds
Class III PPM for SND?
1) SND due to nonessential meds
2) asymptomatic
Class I for PPM w/ AVB
1) sxs brady
2) >3s pauses (>5s if a fib)
3) required meds that cause AVB
4) 2nd degree AVB w/ sxs brady
5) neuromuscular dz (muscular dystrophy, Kearns-Sayre)
6) AVB w/ exercise but no ischemia
7) awake, no sxs , escape rate 40 w/ either LV dysfxn or known to be infranodal block
Class III for PPM w/ AVB
reversible AVB (lyme, drug tox, OSA)
Class I for PPM w/ bi/trifascicular block
1) intermittent 3rd degree AVB
2) 2nd degree type II AVB
3) alternating BBB
Class I PPM for AVB post MI
1) persistent and symptomatic 2nd or 3rd deg AVB
2) persistent infrahissian block (R/LBBB)
3) transient blocks (incld. BBB)
Class III PPM post MI
1) new BBB w/o AVB
2) transient AVB w/o BBB
Class I for CRT
- EF < 35%
- QRS > 150ms
- LBBB (not RBBB!)
- Class II (NEW!), III, or ambulatory IV CHF
what type of syncope is “ominous”
syncope w/ exertion
what tests are low yield for syncope?
neuro
Which phase of AP is If?
4
What is phase 0 (upstroke) of SAN AP due to?
Ca
Which AP phase and current does beta adrenergic stimulation affect?
Phase 4
If
In what phase do early after depolarizations occur?
3
What clinical scenario is associated with early after depolarizations?
Long QT
What phase of AP are delayed after depolarizations seen in?
4
Name 2 clinical scenarios associated with delayed after depolarizations
Calcium overload
Dig tox
What mech of arrhythmia causes DAD’s?
Triggered activity
If you see a wide complex tachycardia with beat to beat variation of axis, what is most likely diagnosis?
Bidirectional VT from dig toxicity
What mech of arrhythmia is scar related VT (monomorphic)
Reentry
Who usu gets primary vasodepressor response on tilt table test? Rx? (Not orthistatic b/c takes time)
LOL with BP drop in church
- hydration, salt, MIDODRINE
What happens in cardio inhibitory response on tilt table test? Who gets it?
Pro drone of nausea then Asystole then BP drop then syncope
Young
What to think of if HV< 35ms?
Pre-excitation
What part of conduction system is most common area of irreversible AV block?
His bundle
What is rate related BBB called?
Ashman phenomenon
How do you program a ppm if there is AVB, you desire AV synchrony but atrial sensing only?
Dual chamber
VDD
Why does high impedance (>3000) of a lead occur?
Lead fracture
Why does low impedance (< 200) of a lead occur?
Insulation compromise
Rx for Pacemaker Mediated Tachycardia
Inc PVARP to blind PPM to retrograde beat
Pacemaker syndrome pt’s have vague complaints; what is Rx?
Programming changes
What class indication is it to put PPM for infra-hissian block or HV > 100ms?
Class II (do it!)
Where is the LV lead placed for CRT?
Lateral LV epicardium or CS if endocardial
According to new guidelines, what class is PPM for QRS 120-149?
IIa
What does beta adrenergic stimulation do to If channel?
Increases the current and makes threshold more negative
