Flashcards in Cardiology_3 Deck (66):
Truncus arteriosus gives rise to what?
ascending aorta and pulmonary trunk
what are the major types of side effects seen in digoxin toxicity?
cholinergic • ECG • hyperkalemia- poor prognostic indicator
what are the cholinergic side effects associated with digoxin toxicity?
nausea • vomiting • diarrhea • blurry yellow vision (VanGogh)
ECG side effects seen in digoxin toxicity?
↑ PR • ↓QT • ST scooping • T wave inversion • arrhythmia • AV block
factors predisposing to digoxin toxicity?
renal failure • hypokalemia • quinidine
how does renal failure predispose digoxin toxicity?
how does hypokalemia predispose digoxin toxicity?
permissive for digoxin binding at K+ binding site on Na/K ATPase
how does quinidine predispose digoxin toxicity?
↓ digoxin clearance; displaces digoxin from tissue binding sites
what is the antidote for digoxin toxicity?
slowly normalize K+ • lidocaine • cardiac pacer • anti-digoxin Fab fragments • Mg++
what type of drug are all the type I Na channel blocker antiarrhythmics?
MOA of class I antiarrhythmics?
↓ conduction (especially in depolarized cells) • ↓ slope of phase 0 depolarization and ↑ threshold for firing in abnormal pacemaker cells
what does it mean that class I antiarrhythmics are state dependent?
selectively depress tissue that is frequently depolarized (tachycardia)
what causes ↑ toxicity for all class I antiarrhythmic drugs?
which drugs are the Class IA antiarrhythmics?
Quinidine • Procainamide • Disopyramide • The Queen Proclaims Diso's Pyramid
MOA of Class IA antiarrhythmics?
↑ AP duration • ↑ ERP • ↑ QT interval
Class IA antiarrhythmias affect what kind of arrhythmias?
atrial and ventricular arrhythmias, especially reentrant and ectopic supraventricular and ventricular tachycardia
cinchonism- headache, tinnitus
reversible SLE-like syndrome
toxicities common to all Class IA antiarrhythmics?
thrombocytopenia, • torsades de pointes due to ↑ QT interval
which drugs are the class IB antiarrhythmics?
Lidocaine • Mexilitine • Tocainide • I'd Buy Lidy's Mexican Tacos • (phenytoin)
which type of antiarrhythmic is best post MI?
MOA of class IB antiarrhythmics?
↓AP duration • Preferentially affect ischemic or depolarized Purkinje and ventricular tissue
Class IB antiarrhythmics are useful in what?
acute ventricular arrhythmias (especially post MI) and in digitalis induced arrhythmias
toxicity of Class IB antiarrhythmics?
local anesthetic • CNS stimulation/depression • cardiovascular depression
which drugs are class IC antiarrhythmics?
flecainide • propafenone
mnemonic for IC antiarrhythmics?
IC is CI in structural heart disease and post MI
MOA of class IC antiarrhythmics?
no effect on AP duration
clinical use of class IC antiarrhytmics?
useful in ventricular tachycardias that progress to VF and in intractable SVT • usually used only as last resort in refractory tachyarrhythmias • for patients without structural abnormalities
toxicity of class IC antiarrhythmics?
proarrhythmic, especially post MI • significantly prolongs refractory period in AV node
effects of class I antiarrhythmics on ventricular AP graph?
all class I- clockwise decrease in slope of phase 0 • IA- prolong AP- rightward stretch of phase 3 • IB- shorten AP- leftward shrink of phase 3 • IC- no effect- barely to the left of normal AP
the class II antiarrhythmics are what type of drugs?
which drugs are used as class II antiarrhythmics?
metoprolol • propanolol • esmolol • atenolol • timolol
MOA of class II antiarrhythmics drugs?
↓ SA and AV nodal activity by ↓ cAMP, ↓ Ca++ currents • suppress abnormal pacemakers by ↓ slope of phase 4
which class II antiarrhythmic is very short acting?
what part of the heart is particularly sensitive to class II antiarrhythmics?
ECG changes seen with class II antiarrhythmics?
↑ PR interval
clinical use of class II antiarrhythmics?
ventricular tachycardia, SVT, slowing ventricular rate during atrial fibrillation and atrial flutter
toxicity of class II antiarrhythmics?
impotence • exacerbation of asthma • CV effects • CNS effects • may mask the signs of hypoglycemia
CV AE of class II antiarrhythmics?
bradycardia • AV block • CHF
CNS effects of class II antiarrhythmics?
sedation • sleep alterations
AE specific to metoprolol?
treat overdose of metoprolol with what?
cardiac AE specific to propanolol?
can exacerbate vasospasm in Prinzmental's angina
which are the class III antiarrhythmics?
Amiodarone • Ibutilide • Dofetilide • Sotalol • AIDS
all class III antiarrhythmics are what type of drug?
K+ channel blockers
MOA of class III antiarrhythmics?
↑AP duration, ↑ ERP
when are class III antiarrhythmics used?
when others fail
ECG changes caused by class III antiarrhythmics?
AE of sotalol?
torsades de pointes • excessive β block
AE of ibutilide?
torsades de pointes
AE of amiodarone?
pulmonary fibrosis • hepatotoxicity • thyroid dysfunction (40% I by weight) • corneal deposits • skin deposits (blue/grey) resulting in photodermatitis • neurologic effects • constipation • CV effects (bradycardia, heart block, CHF)
what are the antiarrhythmic effects of amiodarone?
has class I , II, III, and IV effects because it alters the lipid membrane
what do you need to check when using amiodarone?
PFTs • LFTs • TFTs
effect of all class III antiarrhythmics on ventricular AP curve?
wide rightward stretch in phase 3 prolongs AP and ERP
which drugs are class IV antiarrhythmics?
verapamil • diltiazem
all class IV antiarrhythmics are what type of drug?
Ca channel blockers
MOA of class IV antiarrhythmics?
↓ conduction velocity, ↑ ERP, ↑ PR interval
clinical use of class IV antiarrhythmics?
prevention of nodal arrhythmias (SVT)
toxicity of class IV antiarrhythmics?
constipation • flushing • edema • CV effects (CHF, heart block, sinus node depression)
MOA of adenosine as antiarrhythmic?
↑ K+ out of cells →hyperpolarizing the cell + ↓Ica
adenosine is the drug of choice for what?
diagnosing/abolishing supraventricular tachycardia
duration of action of adenosine?
toxicity of adenosine?
flushing • hypotension • chest pain
effects of adenosine blocked by what?
theophylline and caffeine