Pharmacology - Antiarrhythmics Flashcards
P wave corresponds to:
Atrial activation
Q wave corresponds to:
His, BB, and septum activation
R wave corresponds to:
LV activation
S wave corresponds to:
late RV activation
T wave corresponds to:
ventricular repolarization (direction is opposite of activation
On EKG, Atrial Phase 0 corresponds to:
P wave
On EKG, Ventricular Phase 0 corresponds to:
QRS complex
On EKG, Ventricular Phase 2 corresponds to:
ST segment
On EKG, ventricular phase 3 corresponds to:
T wave
On EKG, the duration of the ventricular action potential corresponds to:
QT interval (start of QRS to end of T)
AVN conduction is measure on EKG by:
PR interval (start of P to start of QRS)
When are U waves (Purkinje repolarization) seen on EKG?
Prolonged QT interval;
Hypokalemia
What is the effect of hypercalcemia on the QT interval?
Increases it
Hypocalcemia decreases it
Wenckebach phenomenon is what kind of arrhythmia?
2nd degree AV block - not every P wave is followed by QRS complex
PR interval gets progressively longer until a beat is dropped
aka Mobitz Type I AVN Block
What is one notable cause of 1st degree AVN block?
Lyme disease
Prolonged PR interval, but 1:1 P:QRS complex
What is the recommended treatment for 2nd and 3rd degree AVN block?
Ventricular pacemaker installation
2/3 of all SVTs are what kind?
AV node re-entry tachycardia
dual AVN conduction pathways
Next most common is bypass tract re-entry - AVN and bypass tract reentry (1/5)
T/F: Adenosine will stop any kind of AVN reentry tachycardia.
Fuck yea it will (so will vagal tone - carotid massage)
What pharmacotherapy is indicated for treatment of WPW syndrome?
Amiodarone (class III anti-arrhythmic - K channel blocker) Procainamide (class IA anti-arrhythmic)
NO AVN blockers - CONTRAINDICATED so NO amlodipine, nifedipine, verapimil, diltiazem)
What is Torsades de Pointes syndrome (TdP)?
A kind of Polymorphic ventricular tachycardia;
associated with long QT interval;
can be genetic
Class IA, IB, IC anti-arrhythmic drugs all have actions where?
Direct membrane action - Na channel blockade
Antiarrhythmics that: Are involved in Na channel blockade; Depress Phase 0; Slow conduction; Prolong repolarization belong to what class?
Class IA
ie Quinidine
Procainamide
Disopyramide
Antiarrhythmics that: Are involved in Na channel blockade; Depress Phase 0 ONLY in abnormal (ie ischemic tissue); Shortern repolarization belong to what class?
Class IB
ie Lidocaine
Mexiletine (oral lidocaine)
Antiarrhythmics that: Are involved in Na channel blockade; Markedly depress Phase 0; Markedly slow conduction; Have a slight effect on repolarization belong to what class?
Class IC ie Flecainide; Propafenone; Moricizine