Anti-rhythmic Drugs Flashcards
What is a common problem associated with digitalis pharmacologic treatment?
Cardiac arrhythmias
Should you treat asymptomatic or minimally symptomatic arrhythmias?
In general, treatment should be avoided
What is depolarization?
When the cells of the heart are activated
What is repolarization?
When the cells of the heart are at rest
What is occuring at the P-wave?
Atrial depolarization
What is occuring at the QRS complex?
Ventricular contraction
What is occurring at the T-wave?
Ventricular repolarization
What is occurring during the ventricular filling phase?
Cardiac muscles are completely repolarized
What is the mechanisms of arrhythmias?
Disturbances in impulse formation and conduction
What regulates the pacemaking activity?
Sympathetic and parasympathetic activity
What are the pacemaking cells in the heart?
Purkinje cells
What phase does disturbed early afterdepolarization (EADs) occur?
Phase 3
What phase does disturbed delayed afterdepolarization (DADs) occur?
Phase 4
EADs are usually triggered by factors that prolong action potential duration in the ventricle which leads to QT prolongation which leads to what adverse effects?
Torsades de pointes (specific V Tach), tachycardia, and other arrhythmias
QT prolongation is caused by a
Blockage of rapidly activating delayed rectifier potassium channels
What is an example of an intrinsic cause of QT prolongation?
Congenital long QT syndrome
What are examples of extrinsic causes of QT prolongation?
Medications (SSRI’s, SNRI’s and others)
DADs can occur when there is an excess of what?
Excess accumulation of intracellular calcium
What are some triggers of DADs?
Digitalis toxicity, excess catecholamines, myocardial ischemia
In complete heart block what cells can dictate ventricular rate?
Latent Purkinje Cells
What is Wolff-Parkinson-White Syndrome?
re-entry circuit of atrial tissue, AV node, ventricular tissue, accessory AV connection (blockage of SA node)
What is the classic pattern seen on EKG in atrial flutter?
Sawtooth Pattern
What are the types of arrhythmias?
Atrial Fibrillation
Atrial Flutter
AV Nodal Re-Entry (SVT)
Ventricular Fibrillation
Ventricular Tachycardia
What are Class 1 anti-arrhythmic agents action?
Sodium channel blockade; these drugs have effects on the action potential duration
Reduce phase 0 slope and peak of action potential