Antiarrhythmics Flashcards
Class 1 antiarrhythmics block what channels? Result in what overall effect to the AP
Voltage gated sodium channels.
Prolongs the phase 0 upstroke and slows the cardiac AP.
Do class 1 antiarrhythmics block open, closed, or inactivated Na+ channels?
Open or Inactivated
What type of cardiac tissues do Class 1 antiarrhythmics have an effect on?
Rapidly depolarizing cells
Class 1 antiarrhythmics have what effect on an ECG?
Increased QRS duration and prolonged AP
Name the Class 1a antiarrhythmics
Quinidine
Procainamide
Disopyramide
Binding affinity of Class 1a, b, and c?
a - Intermediate
b - Low
c - High
Class 1a MOA?
Inhibit Na+ and K+ voltage gated channels. This slows down Phase 0, 2, and 3 and increases the refractory period.
Class 1a treats?
Supraventricular and ventricular arrhythmias
WPW
Class 1a adverse effects?
Cinchonism Thrombocytopenia Lupus like syndrome Exacerbate HF Precipitate torsades
Name the class 1b medications?
Lidocaine
Mexiletine
Phenytoin
Class 1b MOA?
Inhibit Na+ and moderately slow phase 0 upstroke. Decreased phase 2 and 3 leading to a decreased refractory period
Class 1b treats?
Ventricular arrhythmias
Class 1b adverse effects?
Neurological issues
Name the class 1c medications
Flecainidine
Propafenone
Class 1c MOA?
Inhibit Na+ channels strongly and prolong the phase 0 upstroke. There is NO effect on AP duration.
Class 1c treats?
Supraventricular and ventricular arrhythmias
A-fib
Class 1c contraindication?
Ischemic heart disease
Name the class 2 antiarrhythmics
Beta-blockers
Class 2 MOA?
Blocking sympathetic input to the SA and AV nodes. Decrease cAMP. Closure of Calcium channels. Overall prolongation of phase 4. Decreased AV conduction
Class 2 treats?
Supraventricular arrhythmias
A-fib, flutter
Rate control
Class 2 effects on the ECG?
Prolonged PR interval
Class 3 MOA?
Block K+ channels and prolong phase 2 and 3. Prolonged refractory period
What is special about Amiodarone?
Shares properties of class 1, 2, 3 and 4 antiarrhythmics
Name the class 3 antiarrhythmics
Amiodarone
Dofetilide
Ibutilide
Sotalol
Class 3 treats?
Supraventricular and ventricular arrhythmias
A-fib
Amiodarone side-effects
Neurologic Gray corneal deposits Thyroid issues Pulmonary fibrosis Heart block HF Hepatitis Skin discoloration Photodermatitis Inhibits CYP-450
Can class 3 antiarrhythmics induce torsades?
YES
What are class 4 antiarrhythmics?
NDHP CCBs
Name the class 4 antiarrhythmics
Verapamil
Diltiazem
Class 4 MOA
Block Calcium current in the SA and AV nodes. Prolong phase 4, decreased pacemaker, prolonged conduction and prolonged refractory period.
Prolonged PR interval
NDHP treat?
Supraventricular arrhythmias
A-fib
Rate control
NDHP adverse?
Cause heart block
Digoxin MOA
Stimulation of the vagus nerve and AV nodal inhibition
Digoxin treats?
Prevents rapid ventricular response in A-fib
Magnesium treats?
Arrhythmias such as torsades
Adenosine MOA
Activates inhibitory A1 receptors on the myocardium at the SA and AV nodes. Suppresses inward Ca++ current and increases outward current of K+. Overall decreased AV conduction and prolonged refractory period
Adenosine treatment?
Acute supraventricular arrhythmias such as PSVT
Adenosine effect on A2 receptors?
Coronary dilation
Adenosine adverse effects?
Cutaneous flushing
SOB, chest pain, feeling of impending doom
Headache
Hypotension
Adenosine effects are inhibited by?
Caffeine and Theophylline
