Arrhythmias Tutorial

What is the primary pacemaker site within the heart? click here
What are the names of the different phases of action potentials in nodal and non-nodal cardiac tissue? click here
How do nodal and non-nodal tissue differ with respect to the role of different ions in the generation of action potentials? click here
What effects do blocking sodium, potassium and calcium ion conductances have on action potentials in nodal and non-nodal cardiac tissue? click here
What is the effective refractory period (ERP) for cardiac action potentials and what can cause it to lengthen or shorten? click here
How do changes in sympathetic and vagal nerve activity alter ion conductances and action potentials in the sinoatrial node? click here
What are the pathways by which action potentials are normally conducted within the heart? click here
How do autonomic nerves, circulating catecholamines and cellular hypoxia affect conduction velocity within the heart? click here

Arrhythmias and their Pathogenesis

Define each of the following types of arrhythmias:   click here
a.    sinus rhythm
b.    sinus bradycardia
c.    sinus tachycardia
d.    sick sinus syndrome
e.    atrial tachycardia
f.     atrial flutter
g.    atrial fibrillation
h.    junctional escape rhythm
i.     AV nodal blocks - first, second and third degree
j.     supraventricular tachycardia
k.    ventricular premature beat
l.     ventricular tachycardia
m.   ventricular flutter
n.    ventricular fibrillation
How can altered automaticity and conduction cause arrhythmias? click here
What are early- and delayed-afterdepolarizations and what can cause them? click here
What are ectopic foci? click here
Under what conditions and by what mechanisms can a non-pacemaker cell to become a pacemaker cell? click here
What are reentry currents, how can they lead to tachyarrhythmias, and how can changes in conduction velocity and the effective refractory period precipitate reentry currents? click here

Antiarrhythmic Drugs

How does changing the slope of phase 4 of pacemaker action potentials affect the rate? click here
How does changing the slope of phase 0 of action potentials affect conduction velocity? click here
How does changing the duration of phase 3 affect the effective refractory period? click here
How can changing conduction velocity and the effective refractory period abolish reentry tachyarrhythmias? click here
What is the Vaughan-Williams classification scheme? click here
What are the primary and secondary antiarrhythmic mechanisms for each of the following classes of antiarrhythmic drugs?
    Class I
    Class II
    Class III
    Class IV
How do Class IA, IB, and IC drugs differ in their direct and indirect effects on non-nodal action potentials? click here
How do Class IA, IB, and IC drugs affect conduction velocity within the heart? click here
Class IA, IB and IC drugs are used for which types of arrhythmias? click here
What are some side-effects and contraindications for Class IA, IB, and IC drugs? click here
What is the primary mechanism by which Class II drugs suppress arrhythmias? click here
Class II drugs are used to treat which types of arrhythmias? click here
Which Class II drugs are selective and which are non-selective beta-blockers? click here
What is intrinsic sympathomimetic activity and membrane stabilizing activity, and how do these properties affect the antiarrhythmic properties of Class II drugs? click here
What are some side-effects and contraindications for Class II drugs? click here
What is the primary mechanism by which Class III drugs suppress arrhythmias? click here
Class III drugs are used to treat which types of arrhythmias? click here
What are some side-effects and contraindications of Class III drugs? click here
What is the primary mechanism by which Class IV drugs suppress arrhythmias? click here
How do verapamil and diltiazem differ from dihydropyridine calcium-channel blockers in terms of cardiac selectivity? click here
Class IV drugs are used to treat which types of arrhythmias? click here
What are some side-effects and contraindications of Class IV drugs? click here
Describe the pharmacology for each of the following drugs and how they are used in the treatment of arrhythmias:
   adenosine
   magnesium and potassium salts
   digitalis compounds (cardiac glycosides)
   atropine (muscarinic receptor antagonist)
Which drugs are used to treat the following arrhythmias? click here

Sinus tachycardia

Atrial fibrillation/flutter

Paroxysmal supraventricular tachycardia

AV block

Ventricular tachycardia

Premature ventricular complexes

Digitalis toxicity

Revised 08/29/06

DISCLAIMER: These materials are for educational purposes only, and are not a source of medical decision-making advice.