Cardiology_3 Flashcards by B -

Truncus arteriosus gives rise to what?

ascending aorta and pulmonary trunk

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what are the major types of side effects seen in digoxin toxicity?

cholinergic • ECG • hyperkalemia- poor prognostic indicator

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what are the cholinergic side effects associated with digoxin toxicity?

nausea • vomiting • diarrhea • blurry yellow vision (VanGogh)

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ECG side effects seen in digoxin toxicity?

↑ PR • ↓QT • ST scooping • T wave inversion • arrhythmia • AV block

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factors predisposing to digoxin toxicity?

renal failure • hypokalemia • quinidine

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how does renal failure predispose digoxin toxicity?

↓excretion

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how does hypokalemia predispose digoxin toxicity?

permissive for digoxin binding at K+ binding site on Na/K ATPase

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how does quinidine predispose digoxin toxicity?

↓ digoxin clearance; displaces digoxin from tissue binding sites

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what is the antidote for digoxin toxicity?

slowly normalize K+ • lidocaine • cardiac pacer • anti-digoxin Fab fragments • Mg++

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what type of drug are all the type I Na channel blocker antiarrhythmics?

local anesthetics

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MOA of class I antiarrhythmics?

↓ conduction (especially in depolarized cells) • ↓ slope of phase 0 depolarization and ↑ threshold for firing in abnormal pacemaker cells

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what does it mean that class I antiarrhythmics are state dependent?

selectively depress tissue that is frequently depolarized (tachycardia)

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what causes ↑ toxicity for all class I antiarrhythmic drugs?

hyperkalemia

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which drugs are the Class IA antiarrhythmics?

Quinidine • Procainamide • Disopyramide • The Queen Proclaims Diso’s Pyramid

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MOA of Class IA antiarrhythmics?

↑ AP duration • ↑ ERP • ↑ QT interval

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Class IA antiarrhythmias affect what kind of arrhythmias?

atrial and ventricular arrhythmias, especially reentrant and ectopic supraventricular and ventricular tachycardia

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quinidine toxicity?

cinchonism- headache, tinnitus

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procainamide toxicity?

reversible SLE-like syndrome

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disopyramide toxicity?

heart failure

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toxicities common to all Class IA antiarrhythmics?

thrombocytopenia, • torsades de pointes due to ↑ QT interval

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which drugs are the class IB antiarrhythmics?

Lidocaine • Mexilitine • Tocainide • I’d Buy Lidy’s Mexican Tacos • (phenytoin)

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which type of antiarrhythmic is best post MI?

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MOA of class IB antiarrhythmics?

↓AP duration • Preferentially affect ischemic or depolarized Purkinje and ventricular tissue

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Class IB antiarrhythmics are useful in what?

acute ventricular arrhythmias (especially post MI) and in digitalis induced arrhythmias

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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?

β blockers

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?

esmolol

what part of the heart is particularly sensitive to class II antiarrhythmics?

AV node

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?

dyslipidemia

treat overdose of metoprolol with what?

glucagon

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?

↑QT interval

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?

~15s

toxicity of adenosine?

flushing • hypotension • chest pain

effects of adenosine blocked by what?

theophylline and caffeine

clinical use of Mg++ as antiarrhythmic?

effective in torsades de pointes and digoxin toxicity