Dysrythmias Flashcards
imbalance of what can lead to dysrhythmias
potassium
what do class I antiarrhythmics do?
Block Na
what do class Ia Na blockers do?
slow Phase 0 depol
What do phase IB Na do?
shortens Phase 3 repol
What do phase IC Na blockers do?
slow Phase 0 depolarization (better than phase Ia)
what is the prototype of class IA antiarrhythmic?
Quinidine
what does quinidine help with
inhibit ventircular arrhythmias
ectopic arrhytmias
prevent re-entry arrythmias
contradincations for class IA antiarrhythmic agents
Great block SA node dysfunction cardiogenic shock uncompensated heart failure SLE w/ procainamide also schizophrenia
what inhibits the metabolism of quinidine
cimetidine
what induces quinidine
rifampin
barbituates
phenytoin
what is a ADR of quinidine that results in blurred vision, tinnitus, HA, disorientation, psychosis
Cinchonism
Clas I A antiarrhythmic that is a derivative of local anesthetic.
procainamide
what is procainamide metabolized to
N-acetylprocainamide (NAPA) which prolongs duration fo AP (Class III properties)
ADRs with procainamide
HPOTN
reversible lupus like symptoms
asystole or ventricular arrhtymias at toxic concen
depression, hallucinations, psychosis
similar to quinidine. C/I with HF or peripheral vasoconstriction. Used to treat ventricular arrhythmias.
Disopyramide
ADRs with dispyramide
anticholinergic
proarrhythmic
What is the class IB prototype and DOC for cardiac arrhythmias
Lidocaine
MOA of lidocaine
shortens phase 3 reporalization and decrease the duration of the action potential. Suppresses arrhythmias caused by abnormal automaticity
indications for liocaine
administer IV (fist pass metabolism avoided) ventricular arrhythmias post MI or arising from MI
what are other class IB meds?
Mexiletine and TOcainide (PO)
what is a concert with tocainide?
pulmonary fibrosis
prototype of class IC antiarrhythmic
flecainide
MOA of flecanide
blocks sodium channels
slow phase 0 depolarization
indications for class IC anitarrhythmics
refractory ventricular arrhythmias (PVCs)
C/I with classs IC anitarrhythmics
CHF
worse proarrythmic
CLass II anitarrhythmics
propranolol
metoprolol
esmolol
what is the MOA of class II antiarrhythmic agents
diminish phase 4 depoloiarization thus depressing automaticity
Class III antiarrythmic agents
Sotolol
amiodarone
dofetilide
MOA of class III antiarrythmics
Blocks potassium channels prolonging both repolarization and duration of AP thus lengthening effective refractory period.
Indications for class III agents
ventricular and supraventricular arrhythmias.
what class II antiarrhytmic agents can result in torsades de pointes?
Sotalol
what is dofetilide restricted to for Rx capabilities
MD who have completed manufactuer’s training
what do amiodarone contain?
Iodine (can mess up a person’s thyroid)
does amiodarone only have Class III antiarrythmic effects?
No, also has class I, II, IV actions
Indications for amiodarone
refractory SVT
ventricular tachyarrhythmias
Does amiodarone reduce incidence of sudden death or prolong survival in pt. with CHF
No
Why is amiodarone challenging to dose?
Really long 1/2 life (weeks)
long term use of amiodarone can result in what?
pulmonary fibrosis (may not be reversible)
what color will patietns with amiodarone look like
blue skin discoloration
what are class IV agents?
calcium channel blockres
indications for class IV agents (CCB)
Atrial arrhythmias Reentrant supraventricular tachycardia Reducing ventricular rate in atrial flutter and fibrillation HTN Angina
contraindications for class IV agents
pts. With preexisting depressed cardiac function due to negative inotropic properties
what anitarrhytmic reduces moratlity?
beta blockers
Endogenous nucleoside that acts at tissues in the lungs, afferent nerves, and platelets.
MOA: high doses decreases conduction velocity, prolongs the refractory period and decreases automaticity in the AV node.
Adenosine
contraindications for adenosine
2nd and 3rd degree hear block
sick sinus syndrome
indications for adenosine
DOC for abolishing supraventricular tachycardia
does adenosine have a long or short duration of action
very short duration of action
ADRs with adenosine
transient facial flushing
chest pain
dyspnea
bronchospasm
Indicated for control of ventricular rate in Afib and a flutter. MOA: shortens refractory period in atrial/ventricular cells while prolonging effective refractory period and decreasing conduction velocity in Purkinje fibers.
Digoxin
ADRs with digoxin
VTACH/ VFIB (treat w/ lidocaine)
Does acute tx for afib depend on if its paroxysmal or persistent
No
is long term anitarrhythmic drug therapy needed for persistnet atrial fibrillation?
No
what is DOC if patients are hemodynamically unstable and have severe symptoms of afib?
Direct current cardioversion (DCC)
what are initial anticoagulation therapies
UF heparin
LMWH
then do bridge therapy
what meds can be used for ventricular rate control?
digoxin (24-48 hours, if underlying HF)
B-blockers, diltiazem, verapmail (better choices w/o heart failure)
amiodarone (failure of other drugs)
is there improvement in mortality with cardioversion
No
what do you give for chronic a-fib therapy for oral anticoagulation?
Warfarin or Dabigatran
