arrhytmias Flashcards
cardiac conduction pathway
1.impulse begins in the SA node
2. travels from SA to right and left atria
3. electrical conduction slows down in the AV node
4. passes through the bundle of HIS and divides into two lsides
5. passes throught the purkinje fibers
how does the action potential work
Phase 0- rapid ventricular depolarization due to influx of Na causes Ventricular contraction QRS
phase 1- early rapid repolarization Na channel closes
Phase 2- influx of Ca and efflux of K
phase 3- rapid ventricular repolarization efflux of K causes ventricular relaxation
Phase 4 - resting membrane potential
what causes arrythmias
electrolyte imbalances
elevated sympathetic states- hyperthyroidism or infection
drugs that cause QT prolongation
what are the two types of arrythmia
supraventricular - Afib sinus tachy etc, causes hypotension and clot
ventricular arrythmias- premature ventricular contraction, ventricular tachy and VFIB, skipped heart beat
what drugs can cause QT prolongation
antiarrythmatics
abx- quinolones and macrolides
azoles except isavu
antidepressants- tricyclics, SSRIs, SNRIs mirtazapine and trazodone
antiemetic- 5HT3
antipsych - clozapine, chlorpromazine, haloperidol, quetiapine , risperidone
other- donepezil, fingolimod, methadone, tacrolimus
risk factors for QT prolongation
Female
electrolyte imbalance- Hypokal/ Hypomg
high dose of QT drugs
multiple QTC drugs
renal liver disease
can cause torsades and death
what class is Na channel blocker
class1
what class does BB fall under
class II
what are class III drugs
K channel blockers
amiodarone, dronedarone
dofetilide
sotalol
ibutilide
class IV drugs
ca channel blockers non DHPs
diltiazem and verapamil
what are the class I or na channel blockers
lidocaine,
flecainide
propafenone
mexiletine
disopyramide
quinidine
procainamide
rate control drugs
BB(II) or non DHp CCB (IV)
goal is <80 <110 also
non dhp not preffered in HFREF
rhythm control
class III K channel blockers
started 3 weeks before cardiofversions and continued for 4 weeks after
amiodarone
pacerone
hepatoxic
can cause hyper/hypothyroidism, SJS TENS
teratogenic
half life 40-60 days
CYP2C9 2D6 and 3A4 and PGP inhibitor
** decrease digoxin by 50% and warfarin 30-50%
** do not exceed 20mg simva or 40mg lova
digoxin
DIGITEK, DIGOX
Therapeutic range is 0.8-2ng/ml
CRCL<50
decrease dose by 20-25% when converting oral to IV
Antidote DIGIFAB
PGP substrate
