ANTIARRHYTHMICS Flashcards
arrhythmia
- what is it
- types
- path of normal heart beat
abnormal origin, rhythm, or rate of heartbeats
- supraventricular, ventricular, tachyarrythmias, bradyarrhythmias
- some are benign and do not need tx
- SA node in R atrium—> AV node–>bundle of His–> L and R bundle branches—> punkinje fibers
abnormal impulse formation vs conduction
formation- inc automaticity and afterdepolarizations (cause spontaneous early or late beats)
conduction- arrhythmia reentry (reexcitation of specific part of cardiac tissue)
- commonly seen reentry in AV node
drug induced arrythmias
- sympathomimetics
- digitalis glycosides (digoxin)
- torsades de pointe (v tach)
- symp: inc automaticity in SA node, AV node, or His-Purkinje fibers
- digoxin: cause afterdepol by inc calcium influx into cardiac cells, also impair AV node conduction, can cause AV block
- torsades: slow ventricular repol and QT prolongation, caused by cerrtain antiarrhyth drugs, psychotropic, abx, cisapride (misc drug)
non pharm tx for arrhythmias
- cardiac ablation (interrupt reentry circuit)
- ICD (prevent primary and secondary sudden cardiac death)
Type/Class I drugs
- largest group
- Na channel blockers
type 1A, B, C
Class I
type 1A
- MOA
- names
- MOA: block Na/K channel–> SLOW conduction, PROLONG repol
- types: quinidine, procainamide, disopyramide
class 1, type 1A
Quinidine (PO, INJ)
- formulations
- indications
- ADRs
- DDIs
- formulations: avail as gluconate or sulfate salt
- indications: supraventricular and ventricular arrhythmias
- ADRs: CINCHONISM (ASA tox- tinninuts, blurred vision, dizzy), hypotension, GI, thrombocytopenia
- DDI: CYP450 substrate and inhibitor
class 1, type 1A
disopyramide (PO)
- indications
- caution
- ADRs
- DDI
- indications: afib or ventricular arrhyth
- caution: pts w CHF and elderly
- ADRs: **anticholingic effects **(blurry vision, urinary retention), hypotension
- DDIs: CYP3A4 substrate
bad for elderly with alzheimers or dementia, anticholinergic effects can worsen symptoms
class 1, type 1A
procainamide (PO, INJ)
- derivative of?
- indications
- ADRs
- DDIs
- derived from local anesthetic procaine
- Indications: supraventricular, ventricular, produces LESS HYPOTENSION than quinidine IV
- ADRs: lupus like syndrome, hypoten, GI, thrombocytopenia, liver tox
- DDI: CYP2D6 substrate
class 1, type 1B
type 1B
- MOA
- names
- MOA: strong affinity for Na channels in depol ischemic tissue—> SLOW conduction, SHORTEN repol
- good for ventricular arrhythmias
- types: lidocaine, mexilitine and tocainide
class 1, type 1B
lidocaine (INJ, topical)
- other uses
- first pass
- indications
- ADRs
- used as local anesthetic
- first pass effect w PO (inactivated), must be given IV
- Indications: v tach, NOT supraventricular arryth
- ADRs: CVS (bradycardia, hypoten, heart block), CNS (disorient, muscle twitch, paresthesia), PSYCHOSIS, resp depression
class 1, type 1B
mexilitine and tocainide
- first pass?
indications
- ADRs
derivatives of lidocaine
- does NOT undergo first pass, give PO
- indications: long term suppression ventricular arrhyth
- ADRs: GI and CNS, agranulocytosis w tocainide
class 1, type 1C
type 1C
- MOA
- names
- MOA: block Na+ channels—>SLOW conduction (His-Purkinje), NO EFFECT on repol
- types: flecainide, propafenone
class 1, type 1C
flecainide (PO)
- indication
- ADRs
- DDI
- indications: supraventricular arrhythmias, svt
- ADRs: reentry vtach, CHF, GI, CNS
- DDI- CYP450 substrate, CYP2DR inhibitor
class 1, type 1C
propafenone (PO)
- similar effects as flecainide, LESS effect on QT
- indications- same as flec
- ADRs- same as flec, also hematoogical SEs
- DDI: cyp450 substrate, CYP1A2, 2D6 inhibitor
OTHER type 1 drugs (closest to 1C)
- name, MOA, indication
moricizine
- phenothiazine analogue
- similar MOA to flecainide
- indications: life threatening ventricular arrhythmias
type 2- beta blockers
- MOA
- indications
- names
- MOA: inhibit SNS activation (cardiac automaticity and conduction)
- indications: prevent and tx supraventricular arrhythmias
- esmolol, metoprolol, acebutolol
SLOW conduction, dec CO
class 2
esmolol
acebutolol
- route and indication
ESMOLOL
- IV, rapid metabolized, short half life
- indication: acute SVT
ACEBUTOLOL
-PO
- indication: ventricular arrhythmias
class 2
metoprolol and propanolol
PO or INJ
- indication: tx and suppress supraventricular and ventrciular arrhythmias
- metoprolol–> IV in early phase of MI, followed by PO
class 3
- MOA
- names
- MOA: block K+ channels, PROLONG ventricular depol and refractory period
- types: amiodoraone, dronedarone, ibutilide, sotalol, dofetilide, bretylium
class 3
amiodarone
- properties
- MOA
- properties: organic iodone compound, similar to thyroid hormones, LONG half life
- MOA: blocks K, Na, Ca channels, and B adrenergic receptors
class 3
amiodarone
- indications
- ADRs
- DDIs
indications:
- PO for Supraventricular and ventricular arrhyth, a flutter, SVT, vtach
- IV for acute life threatening VF or sustained VT
ADRs- thyroid dysfunc, pulm fibrosis, blue-grey skin
DDIs- CYP450 substrate, inc levels of digoxin, phenytoin, warfarin
class 3
dronedarone
- properties
- MOA
- indications
- properties: shorter half life than amiodarone, less risk thyroid,pulm, neuro side effects
- MOA: like amiodarone
- indicatons: reduce CV hosp. in Afib or Aflutter pts
class 3
dronedarone
- ADRs
- DDIs
- ADRs: like amiodarone, but LESS thyroid, pulm, neuro issues
- DDIs: CYP450, esp digoxin, CCBs, warfarin
class 3
ilbutilide (IV)
- MOA
- indications
- ADRs
- MOA: influx Na+, prolong repol (diff from other class 3)
- indications: rapid conversion of Afib or flutter
- ADRs: TORSADES DE POINTE
class 3
sotalol
- MOA
- indications
- ADRs
- MOA: nonselec BB, block K+ during ventricular AP
- indications: ventricular arrhyth, AFib (AVOID in HF)
- ADRs: dose dependent torsades de pointe, bronchospasm/bradycardia
class 3
dofetilide
- MOA
- indications
- ADRs
- MOA: class 3 moa
- indications: chronic afib, a flutter
- ADRs: dose dependent torsades de pointes
class 3
bretylium
- MOA
- indications
- ADRs
- MOA: prolong ventricular AP
- indications: vfib
- ADRs: orthostat hypotension
class 4
- CCBs (non DHP)
- MOA, indications, names
- MOA: dec AV node conduction velocity
- indications: IV for acute PSVT, PO for Afib (avoid w HF)
- diltiazem and verapamil
misc drugs
- adenosine
- digoxin
- magnesium sulfate
MOA, indication, ADRs
adenosine
- indication: SVT, PSVT (preferred)
- ADRs: flushing, dizzy, bradycard, syncope
digoxin
- MOA: inc vagal tone, slow AV
- indications: AF, PSVT
- ADRs: GI, CNS, arrhythmias (tx w lidocaine)
magnesium
- MOA: slow SA impulse
- indications: VTach, Vfib and torsades de pointe
- ADRs: GI, CNS depression, flushing (dose dep)
managing A FIB
step 1-
- rate v. rhythm control
<48 hrs
FIRST CONTROL RATE
- BB, CCBs, or digoxin
SECONDLY CONTROL RHYTHM (if needed)
- synchronized cardioversion
- cardiac ablation
- pharm cardioversion w CLASS 1 or CLASS 3 (depend on pt PMHx)
- combo therapy
A FIB management- risks
risk of stroke w cardioversion
- ensure adequate anticoag for 3 week prior to cardioversion
- TEE to check for thrombi
A FIB management
step 2
- anticoag
>48 hrs
CHADS2 score
- CHF (1), HTN (1), age>75 (1), DM (1), Hx of stroke (2)
- score 1-2–> ASA QD or warfarin, or N/DOAC (pt preference)
- score 3-6 –> warfarin or NOAC unless CI
DOACs- dabigatran, rivaroxaban, apixaban
