9. Cardiovascular System Drugs

Question 1

Class 1/ sodium channel blockers are used to prevent which condition?

Answer 1

After depolarisations as sodium channels in the open and inactivated state are blocked

Question 2

Give an example of a class 1 drug

Answer 2

Lidocaine

Question 3

What do class 2 drugs do and how do they work?

Answer 3

Beta blockers (block beta 1 adrenoreceptors)
Decreases slope of pacemaker potential in SAN
Inhibits adenyl cyclase so negative inotropy

Question 4

What are class 3 drugs and why are they not used?

Answer 4

They prolong the action potential by blocking K+ channels
(In theory stop after depolarisations by increasing absolute refractory period)
Actually can be pro-arrhythmic so not used

Question 5

How do ACE inhibitors work?

Answer 5

Prevent formation of angiotensin II therefore causing dilation of arterioles and veins - decreases preload and after load

Angiotensin II also promotes aldosterone release - ACE inhibitors therefore reduce water retention hence decreased blood volume and preload on the heart

Question 6

What is the primary function of organic nitrates in the treatment of angina?

Answer 6

Venodilation to decrease venous pressure hence decreasing preload on the heart

Question 7

What is the secondary function of organic nitrates in the treatment of angina?

Answer 7

Acts on coronary arteries improving O2 delivery

Question 8

The atria being stretched can lead to what condition?

Answer 8

Atrial fibrillation due to re entry loops being generated due to damaged myocardium