Cardiology_3 Flashcards
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?
↓excretion
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?
local anesthetics
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?
hyperkalemia
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
quinidine toxicity?
cinchonism- headache, tinnitus
procainamide toxicity?
reversible SLE-like syndrome
disopyramide toxicity?
heart failure
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?
IB
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