Flashcards in Antiarryhthmics Deck (45):
Class IA Sodium channel blocker
-muscarinic receptor blocker
-alpha bloc (possible reflex tachycardia)
-wide clinical use in many arrhthymias; in atrial fibrillation, need initial digitalization (to slow AV conduction)
Class 1 Sodium channel blocker
**********Cinchonism (named after tree that anti malarials come from-Quinines-so seen in any antimalarials only **BUZZ WORD**) - Tinnitus, ocular dysfunction (cannot tell if miosis or mydriasis because it is both a muscarinic and alpha blocker), CNS excitation, GI disturbances (same as eyes explanation)
****Prolongation of QRS and QT interval - Torsades *********
Quinidine drug interactions
Class 1 sodium channel blocker
-Hyperkalemia enhances effects and vice versa
-Displaces digoxin from tissue binding sites
Class 1A Sodium channel blocker
-Less muscarinic receptor block than quinidine
-Metabolized through conjugation by ****N-acetyltransferase****
--therefore affected by slow/fast metabolizers
Class 1 Sodium channel blockers
*****SLE like syndrome*****
CV effects (torsades)
Torsades caused by what type of drugs?
SLE like syndrome is caused by what drugs?
Hydralazine (anti HTN)
Isoniazid (anti TB)
-seen in slow acetylators
Drug induced SLE lab results
Positive anti ANA
*****Positive anti histone******* (specific to drug induced)
Negative anti dsDNA
Class 1A sodium channel blocker
Class 1B Drugs
Sodium channel blockers
-Block fast sodium channels (decrease
-Block ***inactivated*** channels (slow conduction in hypoxic and ischemic heart) -slows cells ability to go back to resting
-Decrease APD - due to block of the slow sodium "window" currents
Lidocaine cardio uses
-Open heart surgery
CNS toxicity (seizures); least cardiotoxic of conventional anti arrhythmics
***IV only*** (due to first pass metabolism)
Mexiletine and Tocainide
Class 1B drugs
Same as lidocaine
Second choice drug (only use if nothing else worked)
-block fast sodium channels especially His-Purinje tissue
-No effect on APD
-No ANS effect
Limited use becase of its proarrhthymic effects leading to sudden cardiac death
Last ditch drug ... some will be saved but many may die too
Beta blockers (see ANS)
-decrease SA and AV nodal activity (parasymp dominance)
-decrease slope of phase 4
Class II Drugs
Non selective (propranolol) and selective (acebutolol, esmolol)
Class II Uses
- negative inotropic effect decreases O2 demand so helpful to reduce reccurence of MI or prevent MI in general
-Prophylaxis post MI, supraventricular tachyarrhythmias (SVT)
-Esmolol (IV) is used in acute SVTs
Which beta blocker is used in treatment of acute supraventricular tachycardias but not for prophylaxis?
Esmolol is indicated for use in what?
Indicated for the rapid control of supraventricular tachycardias in patients with atrial fibrillation or atrial flutter in the peri or post operative setting where rapid, short term control of ventricular rate with an ultra short acting agent is indicated
The beta blockers have what as part of their antiarrhythmic mechanism of action?
Decrease cAMP levels
A patient is diagnosed with congenital long QT syndrome. If this patient is to be treated for cardiac arrhthymias, drugs with which mechanism would most likely be contraindicated?
Block potassium channels would be contraindicated
Congenital long QT syndrome predisposes patients to torsades, therefore those individuals should avoid drugs that May also precipitate torsades. Both class 1A and Class III antiarrhythmic drugs may cause torsades because of their potassium channel blocking ability
A patient on antiarrhthymic drug therapy yexperiences syncopal episodes associated with a prolonged QT interval. The patient also suffers from diarrhea and gastrointestinal upset and complains of ringing in his ears. What drug was prescribed for this patient?
Torsades-K channel blocks
Which antiarrhythmic drug is associated with an increase in mortality when usedprophylactically in ventricular tachycardia?
Class 1C antiarrhthymics -increased sudden death post MI
What Class 1 oral drugs preferentially target ischemic areas of the heart?
Mexiletine and Tocainide
Lidocaine is only IV
Compared with procainamide, which of the following effects is unique to quinidine?
Prolongation of the action potential
Sodium channel block
Systemic lupus erythematosus
Class IA Mechanism
-Block fast sodium channels
-Preferentially in the ***open*** or activated state
-Increase APD and ERP
-Also block potassium channel (prolongs repolarization)
Quinidine, Procainamide, Dispyramide
Class III Mechanism
Potassium channel blockers
-decreased I(k), slowing phase 3
-increase APD and ERP
Amiodarone, Ibutilide, Dofetilde, Sotalol "AIDS"
Class III Potassium Blocker
Mimic classes I, II, III and IV
Increases APD and ERP in all cardiac tissues
half life - greater than 80 days
Amiodarone Side effects
High tissue and protein binding
-Pulmonary fibrosis (restrictive pulmonary disease)
-Blue pigmentation of the skin (smurf)
Decreases I(k), slowing phase III
Beta one blockade, leading to decrease heart rate, decrease AV conduction
Use-life threatening ventricular arrhythmia
If a patient is prescribed sotalol for treatment of an arrhythmia, he was most likely diagnosed with what?
A patient with recurrent supraventricular tachycardia is started on a new medication that has a risk of causing pulmonary fibrosis. What drug?
The class III antiarrhythmics primarily slow what phase?
L type Calcium channel blockers
-block slow cardiac Ca2+ channels
-decrease phase 0, decrease phase IV
-decrease SA, decrease AV nodal activity
Class IV drugs
Calcium channel blockers
Verapamil and diltiazem
Verapamil and Diltiazem Use
Verapamil and Diltiazem Side effects
Verapamil and Diltiazem Drug Interactions
-Additive AV block with beta blockers, digoxin
-Verapamil displaces digoxin from tissue binding sites
If a patient is prescribed verapamil for an arrhythmia she most likely has what?
Paroxysmal supraventricular tachycardia
Diltiazem effects what phase as an antiarrhythmic?
Decreases phase 4
Adenosine is antagonized by what?
Methylxanthines - theophylline (used in COPDs like asthma which can cause V-tach) and caffeine
Magnesium is used for what?
Drugs that cause Torsades
Potassium channel blockers
Antimuscarinics -quinidine, antihistamines