Arrhythmias Flashcards
cardiac conduction pathway
- begins in the SA nodes
- travels from SA nodes to right and left atria causing the atria to contract
- singel reaches atrioventricular (AV) node
- bindle of His
- the bindle of His divides into the right bundle branch for the right ventricle, and
- left bundle branch
- Purkinje fibers
Phase 0 what class of antiarrhythmics
Class Ia, Ib, Ic
phase 0: heartbeat is initiated, when rapid ventricular depolarization occurs in response to an influx of Na, this causes ventricular contractions (QRS complex on ECG)
select drugs increase or prolong QT interval
- antiarrhythmics: Class Ia, Ic, and III
- Anti-infectives: Antimalarials (e.g., hydroxychloroquine), azole (except isavuconazonium), macrolides, quinolones, lefamulin
- Antidepressants: SSRIs (highest citalopram and escitalopram), tricyclic antidepressants, mirtazapine, trazodone, venlafaxine
- Antiemetics: 5-HT3 receptors antagonists, Droperiodol, metoclopramide, promethazine
- Antipsychotics: first gen, second gen (highest with ziprasidone)
- oncology meds: androgen deprivation therapy (e.g., leuprolide), tyrosine kinase inhibitors (e.g., nilotinib), oxaliplatin
other: cilostazol, donepezil, fingolimod, hydroxyzine, loperamide, methadone, ranolazine, solifenacin, tacrolimus
Class I
Ia: Disopyramide, Quinidine, Procainamide
Ib: Lidocaine, Mexiletine
Ic: Flecainide, Propafenone
Class II
beta-blockers
Class III
Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone
Class IV
Verapamil, Diltiazem
Double Quarter Pounder, Lettuce, Mayo, Fries Please!
Because Dieting During Stress Is Always Very Difficult
Class I info
Na-channel blocker
proarrhythmic but negative inotropic, use caution in pt with underlying cardiac disease
Class II info
beta-blockers
blocks sympathetic activity that triggers arrhythmia, indirectly blocks Ca channels, which decreases conduction speed. primarily slows ventricular rate in AF
Class III info
K-channel blockers
Amiodarone and dronedarone block K channels primarily, CA channels, Na channels…
Amiodarone and dofetilide are preferentially used for AF in pt with HF
Sotalol blocks K channel and is a beta-blocker
Class IV info
non-DHP CCBs
slow ventricular rate in AF. negative inotropic effect, don not use in HF pts and HFrEF
Digoxin
Na-K-ATPase blocker
Suppresses AV node conduction (decreases HR), by enhancing vagal tone and increase force of contraction
Adenosine
used for paroxysmal supraventricular tachyarrhythmia
goal resting HR in symptomatic AF
<80
<110 asymptomatic
Rate control
beta-blockers or non-DHP CCBs and sometimes digoxin
rhythm control
- the goal is to restore and maintain NSY
—> Class Ia, Ic or III or electrical cardioversion - if AF is permanent, avoid rhythm-control strategy (risk outweighs the benefit)
stroke prophylaxis
clots can form with pt is in AF- which can embolize and cause stroke when pt returns to NSR
for many pt it is safer to remain in AF w/ rate control than try to restore NSR
rate control strategy may require anticoagulation for stroke prevention
- NOACs (apixaban, rivaroxaban) preferred over warfarin for stroke prevention in non-valvular AF
- warfarin is indicated for AF and a mechanical heart valv
amiodarone
Nexterone, pacerone
t1/2= 40-60 days
pulmonary toxicity, hepatoxic
non-PVC
avoid in pt with iodine sensitivity
Diltiazem
Cardizem, Tiazac
contra in HFrEF, hypo (SBP<90)
HF may worsen symptoms
SE: gingival hyperplasia
Verapamil
Calan SR
Digoxin dose info
Digitek
therapeutic range .8-2ng/ml for AF lower range for HF
CrCL <50 ml/min decrease dose or frequency
decrease dose by 20-25% when converting for oral to IV
antidote: digifab
Disopyramide
norpace
- reserved for life-threatening ventricular arrhythmias
- proarrhythmic, hypotension, myasthenia graves due to anticholinergic
-Class Ia
Quinidine
take with food
may increase moratility
conta: 2/3rd degree heart block, use of other QT prolonging drugs
hemolysis, avoid in G6PD deficiency.
- Class Ia
