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CVS > Drugs > Flashcards

Drugs Flashcards

0
Q

What can CVS drugs alter?

A

Rate and rhythm of the heart
Force of myocardial contraction
Peripheral resistance and blood flow
Blood volume

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1
Q

What can cardiovascular drugs be used to treat?

A 
Arrhythmias
Hypertension
Heart failure
Angina
Risk of thrombus formation
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2
Q

What is atrial flutter?

A

An abnormal heart rhythm that occurs in the atria. Associated with tachycardia (100bpm)

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3
Q

What does atrial flutter look like on an ECG?

A

P waves give a ‘sawtooth’ appearance
4 P waves per QRS complex
Ventricular activation is regular

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4
Q

What is atrial fibrillation?

A

When the atrial muscle fibres contract independently.

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5
Q

What does atrial fibrillation look like on an ECG?

A

No P waves and irregular baseline

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6
Q

What is ventricular fibrillation?

A

When the ventricular muscle fibres contract independently.

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7
Q

Ventricular fibrillation on an ECG?

A

No QRS complex

Completely disorganised

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8
Q

Causes of arrhythmias?

A

Ectopic pacemaker activity
Afterdepolarisations
Re-entry loop

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9
Q

4 classes of drugs to treat arrhythmias?

A

Drugs that block voltage-sensitive sodium channels
Antagonists of β-adrenoceptors
Potassium channel blockers
Calcium channel blockers

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10
Q

What does lidocaine do?

A

A local anaesthetic
Blocks VG Na channel in open or inactive state
Dissociates rapidly in time for next AP
Use-dependent block

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11
Q

Why is lidocaine used following an MI if a patient has ventricular tachycardia?

A

Myocardium damaged so may be depolarised and fire automatically
More Na channels are open in depolarised tissue and lidocaine blocks these channels. Prevents automatic.

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12
Q

Name a β-blocker

A

Propanolol or atenolol

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13
Q

How do β-blockers work?

A

Block sympathetic action by blocking β-1 adrenoreceptors in the heart.
Decrease the slope of pacemaker potential in the SA node.

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14
Q

When are β blockers used?

A

Following an MI to

  • decrease sympathetic activity and therefore prevent ventricular arrhythmias
  • reduce oxygen demand and reduce myocardial ischaemia

Prevent supraventricular tachycardias by slowing conduction in AV node

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15
Q

What do K+ channel blockers do?

A

Lengthen the absolute refractory period

In theory it would prevent another AP from happening too soon, however can be pro-arrhythmic

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16
Q

What does amiodarone do?

A

K+ channel blocker.
Anti-arrhythmic
Also used to treat tachycardia associated with Wolff-Parkinson-White syndrome

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17
Q

What is Wolff-Parkinson-White syndrome?

A

Where there is a re-entry loop due to an extra conduction pathway.

18
Q

Example of a calcium blocker drug?

A

Verapamil

19
Q

How do calcium channel blockers work?

A

Decrease slope of pacemaker action potential in SA node
Decreases AV nodal conduction
Decreases force of contraction
Cause some coronary and peripheral vasodilation

20
Q

What does adenosine do?

A

Acts on α1 receptors at AV node
Enhances K conductance, hyperpolarising cells of conducting tissue
Decreases cAMP levels
Anti-arrhythmic

21
Q

What is heart failure?

A

Chronic failure of the heart to provide sufficient output to meet the body’s requirements.

22
Q

Features of heart failure?

A

Reduced force of contraction
Reduced cardiac output
Reduced tissue perfusion
Oedema

23
Q

What types of drugs are used in heart failure?

A

Positive inotropes to increase cardiac output

Drugs which reduce work load of heart by reducing afterload and preload.

24
Q

What are cardiac glycosides and how do they work?

A

Drugs which increase inotropy.

Block NaKATPase

25
Q

Describe action of cardiac glycosides for increasing contractility?

A

Calcium is extruded by NaCa exchanger, driven by Na moving down conc gradient set up by NaKATPase.
NaKATPase is blocked so there is a rise in intracellular Na.
Decreased activity of Na-Ca exchanger
Increase in intracellular calcium so more calcium in SR.
Increased force of contraction

26
Q

How do cardiac glycosides decrease heart rate?

A

Increase vagal activity. Slows AV conduction. Slows heart rate.

27
Q

How do ACE-inhibitors work?

A

Inhibit action of angiotensin converting enzyme

Prevent angiotensin I ➡️ angiotensin II

28
Q

What does angiotensin II do?

A

Acts on the kidneys to increase Na+ and water reabsorption

Vasoconstrictor

29
Q

Overall effects of ACE-inhibitors?

A

Decrease vasomotor tone
Reduce afterload of the heart

Decrease fluid retention
Reduce preload of the heart

Reduce workload of the heart

30
Q

What is angina due to?

A

Narrowing of the coronary arteries

31
Q

How is angina treated?

A

β-adrenoreceptor blockers
Ca channel antagonists
Organic nitrates

32
Q

How does nitric oxide cause vasodilation?

A

NO activates guanylate cyclase
Increases cGMP
Lowers intracellular calcium concentration
Causes relaxation of vascular smooth muscle

33
Q

How does vasodilation alleviate symptoms of angina?

A

Venodilation lowers preload
Reduces work load on the heart
Heart fills less therefore contraction is reduced (Starling’s Law)
Lowers oxygen demand

34
Q

Which heart conditions can increase the risk of thrombosis?

A

Atrial fibrillation
Acute MI
Mechanical prosthetic heart valves

35
Q

List the antithrombotic drugs

A

Heparin
Warfarin
Antiplatelet drugs (aspirin)

36
Q

What does heparin do?

A

Inhibits thrombin

Used acutely for short term action

37
Q

What does warfarin do?

A

Antagonises action of vitamin K

Used long term

38
Q

What drugs are used to treat hypertension?

A

ACE-inhibitors
β-blockers
Ca channel blockers selective for vascular smooth muscle
Diuretics
α1-adrenoreceptor antagonists for vasodilation

39
Q

What do class I drugs do?

A

Block voltage-sensitive sodium channels

40
Q

Action of class II drugs?

A

Antagonists if β-adrenoreceptors

41
Q

Class III drugs?

A

Block potassium channels

42
Q

Action of class IV drugs?

A

Block calcium channels

CVS (19 decks)

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