January 7, 2016 - Intro to Cardiac Drugs

Question 1

Classification of Cardiac Drugs

Answer 1

Class I - Na⁺ channel blockers

Class II - Beta blockers

Class III - K⁺ channel blockers

Class IV - Ca²⁺ channel blockers

Question 2

Electrophysiology - SA Node

Answer 2

We can change the shape of the action potential by adding drugs.

Class IV (calcium channel blockers) will decrease the slope of stage 0 and slow down the heart.

Class II (beta blockers) will elongate stage 4 and slow down the heart rate.

Question 3

Electrophysiology - AV Myocytes

Answer 3

Na is stage 0

Ca is stage 2

K is stage 3

Question 4

Drugs to Speed Up SA Node

Answer 4

Epinephrine - increase sympathetic activity

Dopamine - increase sympathetic activity

Atropine - decrease parasympathetic activity

Question 5

Pacemaker

Answer 5

Used when drugs cannot sufficiently speed up a slow heart.

QRS will be wide when using an artificial pacemaker because it does not use the natural conduction system.

Question 6

Re-Entry Circuits

Answer 6

Can give a tissue the ability to be a very, very fast pacemaker.

Can be located in different locations all over the heart. Atrial tachycardia may be altered with drugs, AV node tachycardia may be altered with drugs, ventricular tachycardia is difficult and the most deadly.