Arrhythmias II Flashcards
What phase of AP = Automaticity?
phase 4
What phase of AP = conduction velocity
phase 0
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?
AVN> SAN
Mech of Class I antiarrhythmics
Na+ blockers
Class Ia anti arrhythmic and mech
Procainamide (Quinidine, Disopyramide)
Na+ blocker
Class Ib anti arrhythmic and mech
Lidocaine (IV) and Mexilitine (PO)
Na+ blockers
Class IC anti arrhythmic and mech
Flecainide and Propafenone
Na+ blockers
Mech of Class III antiarrhythmics
K+ blockers
Class III antiarrhythmics
Amio
Sotalol
(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)
QT prolonging
Renal dysfunction
Most common use for class Ia drugs
VT (monomorphic)
[also SVT]
are class Ib (lido/mex) use dependent? What does that mean?
Yes, better effect at faster HR
Do lido/mex effect QT?
No!
Can use for afterdepolarizations (dig-induced VT)
Can use for torsades
2 cautions for lido/mex
CHF
Hepatic dysfunction
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?
CAST
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?
yes!
What is mech of class III? What are its 2 clinical uses?
K+ channel blockers
Afib
VT
**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) QT
most effective drug for preventing recurrent AF and for VT/VF?
Amio
Cardiac and Neuro side effects of Amio
bradycardia Long QT/Torsades Hypotension ATAXIA (falling) TREMOR NEUROPATHY
Pulm/Thyroid/GI Side effects of Amio
pneumonitis/fibrosis
hyper/hypothyroidism
increased LFTs/nausea
Ocular/Derm side effects of Amio
corneal deposits
retinopathy
photosensitivity/blue skin
*Important Drug interactions w/ Amio
warfarin, Dig (have to decrease their dosing)
statins
Dronedarone indications and contraindications
Indication: PAF w/ 1 assoc. risk factor (age, HTN, LA>5cm, EF<40%)
Contraindication: Chronic AF- inc. mortality/CVA/HF!
Acute/severe CHF
cirrhosis