Cardio: Class IV Antiarrhythmics Flashcards
What is the basic function of class IV antiarrhythmics?
They, like the class II drugs, slow heart rate. Class IV drugs do so by blocking nodal calcium channels.
What type of calcium channels do the class IV drugs block?
L-type, also called non-dihydropyridine (think of the L-shaped handle of the Non-Dairy soft-serve dispenser)
What are the classic class IV drugs?
Verapamil (Very Vanilla ice cream)Diltiazem (Delicious Dark chocolate)
What do calcium-channel blockers do to the cardiac action potential?
It slows the phase 0 upslope, thereby decreasing sinus activity, prolonging conduction velocity, and lengthening refractory period –all nodal effects.
True or false: class IV drugs can cause increased QT interval.
False. They cause increased PR interval, because they slow conduction between the atria and ventricles.
Which part of the heart can class IV drugs treat?
The atria (think of the broken bottom half of the heart sign), because class IV drugs block nodal rhythms
What kind of arrhythmias can class IV drugs treat?
Atrial fibrillation and atrial flutter (think of the TV with static in the shop) because they prolong conduction time and can prevent the atria from inducing ventricular tachycardias