Cardiovascular Pharmacology

Question 1

What are the indications for using vasodilators?

Answer 1

angina pectoris

heart failiure

hypertension

Question 2

What is pre-load?

Answer 2

The volume of blood in the ventricles before they contract

Question 3

What is after-load?

Answer 3

The force against which the heart has to push the blood (resistance of blood flow)

Question 4

What term describes the volume of blood in the ventricles before they contract?

Answer 4

pre-load

Question 5

What term describes the force against which the heart has to push the blood (resistance of blood flow)?

Answer 5

after-load

Question 6

Explain why blood pressure increases as you get older

Answer 6

As you age, the aorta becomes less pliable (i.e due to natural ageing, muscle thickening etc.) which result in the vessel becoming more rigid and thus unable to dissipate as much of the pressure. Ventricles will have to push harder.

Question 7

in younger people, where can the majority of the after load be found?

Answer 7

in the arterioles

Question 8

What are arterioles?

Answer 8

vessels which direct blood into capilleries

Question 9

In patients with sepsis why might the blood pressure be low?

Answer 9

the arterioles are fully dilated due to toxins in the body causing blood to leak out thus blood pressure

Question 10

Whe you have heart failiure, what is the usual state of the vessels and why?

Answer 10

vasoconstriction to compensate for low blood pressure.

Question 11

In older peopd, where is most of the after-load, likely to be found?

Answer 11

on an aortic level

Question 12

Would you need greater or less force if there is greater pre-load?

Answer 12

greater force

Question 13

Would you need greater or less force if there is less pre-load?

Answer 13

less force

Question 14

is a higher pre-load in ischaemic instances good or bad?

Answer 14

bad

Question 15

Why is it unfavorable to have a high pre-load in ischaemic instances?

Answer 15

in ischaemic situations, there is already high oxygen demand.

A higher pre-load will require more energy/force which will inturn require more oxygen.

the less oxygen being delivered can result in more infarcted tissue

Question 16

How do vasodilators affect pre-load and how?

Answer 16

vasodilators reduce pre-load by causing blood to pool in the major veins of the body

Question 17

What is the popular pre-load reducing medication/substance?

Answer 17

organic nitrates.

Question 18

How do organic nitrates affect pre-load?

Answer 18

They reduce pre-load by relaxing arterial and venous smooth muscle via liberation of nitric oxide.

Question 19

Do organic nitractes have a cardiac or vascular effect?

Answer 19

vascular effect - no cardiac effect whatsoever

Question 20

In the case of angina pectoris what are the levels between o2 supply and o2 demand

Answer 20

o2 supply< o2 demand

Question 21

how much do blood vessels need to be narrowed befor one get’s ischaemia/ ischaemic pain?

Answer 21

75%

Question 22

in ischaemic instances/ angina pectoris, what medication may be administered to the patient?

Answer 22

organic nitrates to decrease oxygen demand

Question 23

Describe the mechanism for the decrease in o2 demand when taking nitrates

Answer 23

Nitrates are convert to Nitric oxide - a substance which causes vasodilation of blood vessels

Blood pools peripherally which reduces pre-load in ventricles.

This means less force is required to pump the blood which inturn mean less O2 consumption

Question 24

What are the hemodynamic effects of nitrates?

Answer 24

venous dilation

• reduced preload
• reduced ventricular size
• reduced vent. wall stress
• reduced o2 demand

coronary vasodilation
- increased mycardial perfusion;redistributes blood flow.

Arterial vasodilation

• decreased afterload –>
• incraesed cardiac output
• decreased blood pressure

Reflex Tachycardia

No direct myocardial action

Question 25

List examples of typical nitrate vasodilators?

Answer 25

glyceryl trinitrate (nitronol)

isosorbide mononitrate (ismo)

isosorbide dinitrate (angitak)

Question 26

List some side effects of taking nitrates

Answer 26

Tachycardia

flushing

hypotension

headache

dizziness

Question 27

what type of proteins in the body convert Nitrates to nitric oxide in the body?

Answer 27

enzymes

Question 28

How can prolonged use of nitrates affect it’s efficacy?

Answer 28

Nitrates have an agonist affect on the body

body will develop tolerance to it

resulting in decreased efficacy of the drug.

Question 29

why does Nitrates induce headaches in some patients?

Answer 29

Increases inter-cranial pressure due to vasodilation in the head.

Question 30

What does the amount of tolerance towards nitrates depend on?

Answer 30

the dose

Question 31

How can you avoid/minimise patient tolerance towards nitrates?

Answer 31

intermittent administration

use lowest possible dose

intersperse a nitrate-free interval

Question 32

What is normally done for a patient whose angina pain returns during the nitrate free interval?

Answer 32

A breakthrough drug which has the same action but does not contain nitrates is usually prescribed. This ensures that effects remain within the therapeutic index

Question 33

How do calcium channel bloockers work?

Answer 33

Blocks calcium channels

prevents the entry of calcium into the cell

which in turn cause the smooth muscle to dilate

Question 34

How does calcium channels affect afterload?

Answer 34

by preventing calcium entry into smooth muscle sphincters in the arterioles causing them to dilate.

causes blood to pool peripherally in capillaries and reduces BP causing a decrease in after-load.