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Year 1: Drug Revision > Cardio: Drugs affecting HR + Force > Flashcards

Cardio: Drugs affecting HR + Force Flashcards

1
Q

HCN channels mediate the funny current. Which drug acts on these channels?

A

Ivabradine

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2
Q

What affect does blocking HCN channels have on the slope of the pacemaker potential and thus the HR?

A

Decreases slope of the pacemaker potential and so decreases HR

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3
Q

What are the clinical uses for Ivabradine?

A

Angina

Heart failure

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4
Q

Which drugs are examples of Beta adrenoreceptor agonists?

A

Adrenaline

Dobutamine

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5
Q

What affects do beta adrenorecptor agonists have on the heart?

A

Increase HR + force of contrition (Positive inotropic + chronotropic effect)
Increase cardiac output
Redistribute blood flow to the heart

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6
Q

When is adrenaline used clinically?

A

IM in anaphylactic shock

IV in cardiac arrest

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7
Q

When is dobutamine used clinically?

A

In acute but potentially reversible heart failure (e.g. due to shock/after surgery)

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8
Q

Which beta adrenoreceptor antagonists are selective for B1 receptors?

A

Atenolol
Bisoprolol
Metoprolol

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9
Q

What effects do B1 adrenoreceptor antagonists have on the heart?

A

Slow HR by delaying conduction through AV node
Increase duration of diastole
Decrease sympathetic activity

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10
Q

Which drug is non-selective for B1 and B2 adrenoreceptors?

A

Propanolol

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11
Q

What are the clinical uses of beta-blockers?

A

1) Angina - slows HR + reduces demand on the heart
2) AF + SVT’s - decrease excess sympathetic drive + help restore normal sinus rhythm
3) Heart failure
4) Hypertension

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12
Q

List the 6 main side effects of beta-blockers

A

1) Bronchospasm
2) Cold peripheries
3) Hypoglycaemia
4) Fatigue
5) Aggravation of HF
6) Bradycardia

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13
Q

Which drug is a non selective antagonist of muscarinic receptors?

A

Atropine

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14
Q

What effect does atropine have on the heart?

A

Increases HR, has no affect on BP

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15
Q

What is atropine used to treat?

A

Bradycardia

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16
Q

What dose of atropine must be given in order to prevent HR decreasing further?

A

No less than 300 micrograms

17
Q

What type of drug is digoxin?

A

A positive inotrope (Increases contractility)

A negative chronotrope (Decreases HR)

18
Q

Where does digoxin bind?

A

The alpha subunit of Na+/K+ ATPase in competition with K+

19
Q

How does digoxin affect vagal activity?

A

Increases it - slows SA node discharge, slows AVN conduction + increases refractory period

20
Q

What are the clinical uses of digoxin?

A

Used to slow rapid AF

Used in HF where all other treatments are ineffective

21
Q

Which body state can dangerously enhance the effects of digoxin?

A

Hypokalaemia

22
Q

What are the adverse effects of digoxin?

A

Arrhythmia

Toxicity - yellow vision + nausea

23
Q

Which drug reverses digoxin toxicity?

A

Digiband

24
Q

What affect to calcium channel antagonists have on the heart?

A

Prevent opening of L-type calcium channels in the heart + smooth muscle to decrease Ca entry
This slows HR

25
Q

Which calcium channel antagonist is selective for smooth muscle?

A

Amlodipine (dihydropiridine)

26
Q

Which calcium channel antagonist is selective for cardiac smooth muscle?

A

Verapamil (rate limiting)

27
Q

Which calcium channel antagonist has selectivity for both cardiac and smooth muscle L-type channels?

A

Diltiazem (rate limiting)

28
Q

What are the clinical uses of calcium channel antagonists?

A

Hypertension - amlodipine reduces MAPB
Angina- diltiazem reduces after load + myocardial demand
Arrhythmia- verapamil slows AVN conduction, useful in AF

29
Q

Which drug must not be used in combination with a calcium channel antagonist?

A

Beta-blockers

30
Q

What are the main side effects of calcium channel blockers?

A

Ankle oedema, hypotension, flushing (dihydropiridines)

Headache, risk of heart block(verapamil)

31
Q

How does the action of levosimendan cause a positive inotropic effect?

A

It binds to troponin in cardiac muscle and increases its sensitivity to calcium

32
Q

What condition can levosimendan be used to treat?

A

Acute heart failure (given IV)

33
Q

Which inotropic drugs inhibit PDE?

A

Amrinone

Milrinone

Year 1: Drug Revision (15 decks)

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