Cardiovascular pharmacology 1

Question 1

What is inotropy?

Answer 1

Contractility of the cardiac muscle

Question 2

What is lusitropy?

Answer 2

Relaxation of the ventricles

Question 3

Affecting preload will have which affect which 2 things?

Answer 3

Circulating volume

Vascular resistance

Question 4

Affecting afterload will affect the…?

Answer 4

Vascular resistance

Question 5

What are the overall effects of the following drugs on the heart:

1. Positive inotropes
2. Lusiotropes
3. Positive chronotropes
4. Negative inotropes
5. Negative chronotropes

Answer 5

1. Increase contractility
2. Change relaxation
3. Increase heart rate
4. Decrease contractility
5. Decrease heart rate

Question 6

Which drug is used in the case of atrioventricular block?

Answer 6

Positive choronotropes

Question 7

Which drug is used in dilated cardiomyopathy cases?

Answer 7

Positive inotropes

• it is disease of the heart muscle that causes the ventricle to stretch and dilate

Question 8

Rate is determined and altered by which 2 factors?

Answer 8

• CV centre in the medulla oblongata

- Autonomic NS

Question 9

Conduction of the action potential is reliant on which 3 factors?

Answer 9

• Normal activity of Na+, K+ and Ca++ channels
• Normal intracellular and extracellular levels of these ions
• Correct function of intercalated discs

Question 10

What may cause control of heart rate and rhythm to go wrong?

Answer 10

• Ectopic pacemakers
• Damage to conducting tissue
• Depression of the CV centre

Question 11

What is a tacharrhythmia?

Answer 11

A heart rate that exceeds the normal resting rate

Question 12

What is the problem with tacharrhythmias?

Answer 12

• ↓diastolic filling time = ↓EDVV = ↓SV = ↓CO
• Can be severe and cause fainting and sudden death
• Increased cardiac work leads to myocardial hypertrophy

Question 13

What factors can we change to slow heart rate?

Answer 13

• Reduce firing rate

- Slow conduction of impulses

Question 14

Which group of drugs do we use to slow the heart down?

Answer 14

Antidysrhythmics

Question 15

What is the overall function of each of the 4 classes of antidysrhythmics?

Answer 15

I = drugs which block fast sodium channels
II = β blockers
III = drugs which prolong the AP by blocking some K channels
IV = Drugs which block calcium channels

Question 16

Out of class I A,B and C, which is a weak, moderate and strong sodium ion channel blockade?

Answer 16

B = weak
A = moderate
C = strong

Question 17

How do class I A, B and C each effect the effective refractory period?

Answer 17

A - increases the ERP
B - decreases the ERP
C - doesn’t change the ERP

Question 18

How does the type of sodium channel effect the drugs?

What is the importance of this?

Answer 18

They are more likely to act on an active sodium channel than an inactive channel.
Reduce heart rate in tachyarrhythmias while not significantly affecting normal heart rates.

Question 19

What are class I antidysrhythmics dependant on?

Answer 19

Normal extracellular potassium for function

Question 20

What is the effect of hyper- and hypo- kalaemia on class I antodysrhytmics?

Answer 20

Hyperkalemia increases their function

Hypokalemia reduces their function

Question 21

Name the Class Ia and Class Ib antidysrhythmic used in practice

Answer 21

Ia = Quinidine 
Ib = Lidocaine

Question 22

What are the adverse effects of using quinidine?

Answer 22

• Various rhythm disturbances as blockade persists
• Negative inotropy & vasodilation –> Congestive heart failure
• GI signs, Nervousness, depression
• Need 24 hour monitoring

Question 23

How are quinidine and lidocaine administered?

Answer 23

Quinidine = Oral route preferred 
Lidocaine = slow IV parental

Question 24

What are the predicted effects of Class II antidysrhythmics (Beta blockers)?

Answer 24

• Slow the pacemaker potential by slowing the calcium influx
• Slow conduction through the AV bundle as increases the refractory period
• Also negative inotropy and reduced lusitropy

Question 25

Where might beta blockers be useful?

Answer 25

- Supraventricular or ventricular tachycardias | - Hypertension

Question 26

What is the Class II antidysrhythmic used in practice?

Answer 26

Atenolol

Question 27

What are the mechanisms of action of class III antidysrhythmic?

Answer 27

- Prolong the cardiac AP - Block potassium ion channels which slows repolarisation (so cells are depolarised for longer, slowing the HR) and increases the refractory period

Question 28

What is the Class III antidysrhythmic used in practice?

Answer 28

Sotalol

Question 29

What makes up Sotalol?

Answer 29

A mixture of two isomers: I-isomer which is a non-selective beta blocker D-isomer which inhibits potassium ion channels

Question 30

What are the effects of Class IV antidysrhythmics?

Answer 30

- Block Ca channels - Shorten the plateau phase - Slows conduction in the SA and AV nodes - Cause partial AV block

Question 31

What effect do Class IV antidysrhythmics have on inotropy and lusitropy?

Answer 31

Negative inotropes | Positive lusitropes

Question 32

Describe the Class IV antidysrhythmic is used in practice?

Answer 32

Diltiazem - administered orally and parentally - coronary and systemic vasodilator

Question 33

Which class does Digoxin belong to?

Answer 33

Class V -miscellaneous

Question 34

What is digoxin used for?

Answer 34

- Negative chronotropic effects (decreases HR) - Enhances the action of the vagus nerve in the heart, mimicking the action of the parasympathetic NS - Slows conduction through the AV node by increasing the refractory period

Question 35

What do most bradyarrhythmias require if they are causing clinical signs?

Answer 35

Pacemaker implantation

Question 36

Which 2 groups of autonomic drugs can be used to treat bradyarrhythmias?

Answer 36

- Sympathomimetics | - Anticholinergics