Antidysrhythmics Flashcards
Dysrhythmia
abnormal rate or rhythm of heart
The electrical conduction of the heart
SA node –> AV node —> Bundle of HIS —> Purkinje Fibers
SA Node
Gate keeper of heart
AV node
gateway for impulse to reach the ventricles; delays impulse travel
Automaticity
heart’s ability to generate an electrical impulse
Conductivity
ability of heart to transmit electrical impulses
How are action potentials generated?
by movement of ions into and out of the cell
Slow action potentials
SA and AV nodes
Fast Action Potentials
Myocardium and His-Purkinje system
Conducts electricity quickly through the heart
depolorization
contraction
P wave
depolarization of the atria
QRS complex
depolarization of the ventricles
T wave
repolarization of the ventricles
PR interval
time between onset of P and onset of QRS complex
QT interval
time between onset of QRS complex and end of T wave
ST segment
between end of QRS complex and start of t wave
ectopic
impulses starting in cells other than SA node
Causes of dysrhythmia
Disturbances of automaticity
Disturbances of conduction
Supraventricular Tachy
Intervention: vasalva maneuvers/Cardioversion
Drug Therapy: Adenosine/Class II or IV Drugs
Atrial Fibrillation
Interventions: Cardioversion
Drug Therapy: Class II or IV drugs/ Anticoagulation
Atrial Flutter
Intervention: Cardioversion
Drug Therapy: Class II or IV drugs/ Anticoagulation
Sustained Ventricular Tachycardia
Intervention: Cardioversion
Drug Therapy: Procainamide, Lidocaine, Amiodarone
Ventricular Filbrillation
Life threatening
Intervention: Cardioversion/CPR
Drug Therapy: Amiodarone/Lidocaine
Torsades de Pointes
Life threatening
Intervention: Cardioversion/ Stop QTc prolonging drugs
Drug Therapy: Magnesium
Class I
Sodium Channel Blockers
Class II
Beta-Blockers
Class III
Potassium Channel Blockers
Class IV
Calcium Channel Blockers
Sodium Channel Blockers
Double Quarter Pounder Lettuce Mayo Fries Please
Sodium Channel Blockers
Class 1A
Disopyramide
Quinidine
Procainamide
Sodium Channel Blockers
Class 1B
Lidocaine
Mexiletine
Sodium Channel Blockers
Class 1C
Flecainide
Propafenone
Adverse Effects Quinidine
Diarrhea 1/3 patients (33%)
Cinchonism
Cinchonism
hearing loss, tinnitus, dizziness, flushing, and blurry vision
Adverse Effects for Procainamide
SLE (Lupus) reaction : rash
Blood dycrasias : blood abnormalities
Arterial embolism : clot traveling in artery
Adverse Effects for Lidocaine
CNS effects
Toxic Doses: seizure, respiratory arrest
Monitoring Considerations for Lidocaine
Narrow therapeutic index
Monitor: drug levels
Monitoring Considerations for Flecainide
Increase mortality in post MI patients with asymptomatic Vtach
4 Approved drugs for Class II: Beta-blockers
Propranolol
Acebutolol
Esmolol
Sotolol
Adverse Effects of Propranolol
Av Block
Sinus Arrest
Hypotension
Bradycardia
Monitoring of Propranolol
Give IV SLOWLY to avoid hypotension
Monitor: HR, BP, ECG
Monitoring of Esmolol
Very fast acting
Short half-life
Monitor: HR, BP, ECG
Monitoring of Sotalol
also causes blockage of K channels; can be considered Class II
Monitor: HR, BP, ECG
Adverse Effects of Amiodarone
Toxicity: lungs, liver, eyes, thyroid
Photosensitivity
Monitoring of Amiodarone
Hypotension
give through 0.22 micron filter
Adverse Effects of Dronedarone
Photosensitivity
Hepatotoxicity
Monitoring of Dronedaron
Contraindicated in pregnancy
Monitoring of Dofetilide
initiated therapy in the hospital
Monitoring of Sotalol
Class II and III agent - do NOT use like a typical beta-blocker
Adenosine Mechanism of Action
Decreased automaticity of SA node
Decreased Conduction through the AV node
Prolonged PR interval
Adenosine Indications
Termination of SVT ONLY
NOT for treatment of afib or aflutter
Adenosine Pharmokinetics
EXTREMELY short half-life (2-10 seconds)
Must be given IV push
Adenosine Adverse Effects
momentary asystole
Chest discomfort
Flushing (at least 20mL)
Adenosine Drug Interactions
Methylxanthines (ex. theophylline) block adenosine receptors, do not give drug if patient is on this
Digoxin Physiologic effects
decreased conduction through AV node
increases vagal tone
high drug level usually needed
Digoxin Indications
atrial fibrillation
atrial flutter
What do Sodium Channel Blockers do?
Decrease conduction velocity in the atria, ventricles and His-Purkinje system
What do Beta-Blockers do?
Decrease automaticity in SA node
Decrease conduction velocity through AV node
Decrease myocardial contractility
Class III: Potassium Channel Blocker Drugs
Amiodaron Ibutilide Dofetilide Dronedarone Sotalol
What do Potassium Channel Blockers do?
delay repolarization of fast action potentials
Prolong the QT interval
What is a common Adverse Drug Effect (ADE) with IV administration
Hypotension
What is something to consider relating to Class III drugs?
All of the medications here can cause QT elongations leading to Torsades de Pointes
What do Calcium Channel Blockers Do?
Decrease SA node automaticity
Decrease AV node conduction velocity
Decrease myocardial contraction
Calcium Channel Blocker Drugs
Diltiazem
Verapamil