Flashcards in Arrhythmias II Deck (86):
What phase of AP = Automaticity?
What phase of AP = conduction velocity
What phase of AP = refractory period
phase 2 & 3
what phase of AP's do BB's effect?
Phase 4 (slows automaticity)
- also slows SAN & AVN
which node do CCB's slow more?
Mech of Class I antiarrhythmics
Class Ia anti arrhythmic and mech
Procainamide (Quinidine, Disopyramide)
Class Ib anti arrhythmic and mech
Lidocaine (IV) and Mexilitine (PO)
Class IC anti arrhythmic and mech
Flecainide and Propafenone
Mech of Class III antiarrhythmics
Class III antiarrhythmics
(Ibutilide, Dofetilide, Dronedarone)
What phase do class I antiarrhythmics effect mainly?
Phase 0 (and 2 & 3)
What to watch out for w/ class Ia drugs (procainamide, disopyramide, quinidine)
Most common use for class Ia drugs
are class Ib (lido/mex) use dependent? What does that mean?
Yes, better effect at faster HR
Do lido/mex effect QT?
Can use for afterdepolarizations (dig-induced VT)
Can use for torsades
2 cautions for lido/mex
Which antiarrhythmics are the most potent Na+ blockers?
Class Ic (flecainide, Propafenone)
Because they are the most potent Na+ blockers, what widens on ECG with Propafenone/flec?
QRS (not QT)
Used for a fib or refractory SVTs (refused ablation, other meds didn't work)?
Class Ic (flec/propafenone)
When is mortality increased with Class Ic (flec/propafenone)
structural heart dz (LV dysfxn, LVH, MI, ischemia)
what is a common/serious pro arrhythmic effect of class Ic? what is the Rx for it?
Can slow Aflutter and cause 1:1 AV conduction.
Use with AVN blockers
which trial showed that class Ic meds (flecainide, propafenone) had increased mortality with structural heart dz?
Even thoughts it a Class III (phase 3), what phases of AP does Amio effect?
Phase 0, 3, 4.
can you get sinus brady with amio?
What is mech of class III? What are its 2 clinical uses?
K+ channel blockers
**Side effects of Class III drugs? Why?
Long QT/Torsades;, exacerbated by hypo Mg/K. Reverse-use dependence (works at slower HR---> torsades)
What to monitor with Class III meds?
Renal dysfxn (contraindicated)
most effective drug for preventing recurrent AF and for VT/VF?
Cardiac and Neuro side effects of Amio
Pulm/Thyroid/GI Side effects of Amio
Ocular/Derm side effects of Amio
*Important Drug interactions w/ Amio
warfarin, Dig (have to decrease their dosing)
Dronedarone indications and contraindications
Indication: PAF w/ 1 assoc. risk factor (age, HTN, LA>5cm, EF<40%)
Contraindication: Chronic AF- inc. mortality/CVA/HF!
Class IV agents, mech
L-type CCB's (phase 0 and 4)
what do Class IV CCB's do to AVN?
prolong conduction and refractoriness
1) BLOCKS Na-K ATPase -> increases intracellular Ca-->inotropy
2) increases vagal tone in central CNS
3) decreases AVN conduction/increases refractoriness
Best use for Dig
AF w/ RVR in CHF
what arrhythmia can dig overdose cause?
PAT w/ variable AVB
-binds to Adenosine (A1) receptor
-causes compete AVB transiently (dec. cAMP--> dec Ca/Na into cells)
- reduces automaticity (hyperpolarizes cell men by inc. K+ outward)
*what is adenosine's action in the atria? What is Rx?
shortens atrial refractoriness--> propensity for AF (b/c of inc'd outward K+ flow).
asthma/diagnose and treat SVT
*adenosine response for:
AVNRT/AVRT - terminates
Focal AT- AV block can inc./doesnt usu. terminate
AF/Flutter- unmasks AF/FL/AVB can inc.
which patients cannot get adenosine due to hypersensitivity?
Dig tox Rx?
Do NOT check dig levels after (they will be very high)
ocular side effect of atropine
which gender is more likely to get a fib?
A/C protocol for AF DCCV
TEE-guided or 3 weeks w/ INR>2.
at CHADS=2, what is annual stroke rate?
4% (start A/C)
CHADSVASC score = CHADS of 2?
what age gets a point in CHADSVASC?
Dabigatran (Pradaxa) mech/trial/dose/M&M
-direct thrombin inhibitor
- 150 BID
- superior to warfarin (dec mortality, ICH) but more GIB
which NOAG is potentially dialyzable? does it have a reversal agent?
Rivaroxaban (Xarelto) mech/trial/dose/M&M
-Factor Xa Inhibitor
- 20 BID
- Noninf. to warfarin/dec. ICH
how are the NOAGs mainly excreted?
renal and feces
Apixaban (Eliquis) mech/trial/dose/M&M
-superioir to warfarin/marked dec. in major bleeding/dec. ICH
what type of bleeding do all the NOAGs decrease c/t warfarin?
who do you rhythm control in a fib?
CHF from AF
if no cardiac dz, what antiarrhytmics do you use for a fib?
Class III (all but ibutilide: dronedarone/sotalol/amio for refractory AF/dofetilide
Class Ic (flecainide/propfenone)
if pt. has CAD, best rhythm control strategy for AF?
Class III or ablation
If pt. has HTN, best rhythm control strategy for AF?
Class III/Ic drugs
**if bad LVH (>1.5cm thick): have to use AMIO or ablation
*if pt. has CHF, rhythm control strategy for AF?
Dofetilife (not if on HD)
contraindicated meds in AF w/ bypass tracts
Treatment for AF w/ bypass tracts
why ablate AF?
which patients do you never send for AVN ablation?
AF ablation success rates after 1st and 2nd procesure?
1 procedure: 60-80%
2nd procedure: >80%
major complication rate s/p AF ablation?
which pts do best after AF ablation?
LA < 5cm,
no pulm dz/OSA.
ibutilide use and monitoring protocol?
-acute conversion of afib (better for AFl)
- >4hrs of monitoring QT.
at what QTc is dofetilide (Tikosyn) contraindicated?
what is the dosing algorithm for dofetilide accoridng to CrCl?
60ml/min: 500 BID
what happens if, after 2nd dose of dofetilide, QTc>500ms
after checking QTc 2h after dofetilide, what is protocol?
if QTc inc'd >15% or is >500ms, decrease dose
Name 3 factors that can make a prolonged QT turn into torsades
Do you treat torsades with IV mag even if Mag level is normal?
Antiarrhythmic to Rx torsades
When is no anticoagulatuon or ASA OK in afib?
No heart dz
Abnormal liver or kidneys (Cr>2.6)
drugs or alcohol
What HAS-BLED score indicates high risk?
Which NOAG can actually reduce mortality c/t warfarin?
When is Amio a first line agent as an antiarrhythmic in afib?
In CHF or Severe LVH (>1.5cm)
If a pt with multiple comorbidities (76y, HTN, DM, etc) comes in to clinic with afib and sxs but stable, what is your initial recommendation ?