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Cardiovascular > Bradyarrhythmia and inotropy pharmacology > Flashcards

Bradyarrhythmia and inotropy pharmacology Flashcards

1
Q

What is AV block?

A

Interruption of impulse from atria to ventricles

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2
Q

What is sick synus syndrome?

A

Dysfunctional SAN

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3
Q

What is atrial standstill?

A

Failure of atrial depolarisation - temporary/permanent lack of atrial activity

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4
Q

What is a problem with all CV pharmacology?

A

Combination of problems and side effects - patients rarely have one condition

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5
Q

Are bradyarrhythmias more or less common than tachyarrhythmias? What may bradyarrhythmias require?

A

Less common

Pacemaker

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6
Q

How does the body physiologically increase heart rate? Why is this a problem for bradyarrhythmic pharmacology?

A 
Increased sympathetic nervous system activity
Pathway broken (unlike in tachycardia)
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7
Q

What are the 4 categories of positive chronotropes used to treat bradyarrhythmias?

A

Sympathomimetics
Anticholinergics
Methylxanthine
PDE III inhibitors

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8
Q

How do methylxanthines work?

A

Reduce hyperpolarisation of cell through potassium channels

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9
Q

Give an example of a methylxanthine?

A

Theophylline

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10
Q

What does PDE do? What is PDE III?

A

Degrade intracellular cAMP

Heart specific PDE

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11
Q

What happens if PDE is inhibited?

A

Increased intracellular cAMP
Activates protein kinase
Phosphorylates calcium
Stronger contractions

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12
Q

Give an example of a PDE III inhibitor

A

Pimobendan

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13
Q

What are the 2 types of sympathomimetics? Give an example of each

A

B1 agonists - dobutamine

B2 agonists - terbutaline

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14
Q

What effects do B1 agonists have?

A

Positive chronotropy

Positive inotropy

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15
Q

What effects do B2 agonists have?

A

Positive chronotropy

Positive dromotropy

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16
Q

What effect do anticholinergics have? What can they be used for?

A

Positive chronotrope
Positive dromotrope
Short term anaesthesia

17
Q

Give an example of an anitcholinergic

A

Atropine

18
Q

What are the 3 categories of positive inotropes?

A

Sympathomimetics
PDE III inhibitors
Cardiac glycosides
(Anticholinergics, glucagon)

19
Q

How do positive inotropes generally cause increased contractility?

A

Mimic/enhance sympathetic activity
Increase intracellular Ca2+
Increases EDVV

20
Q

PDE III inhibitors are positive chronotropes and inotropes. What other effects do they cause?

A

Vasodilation

Faster depolarisation

21
Q

How do PDE III inhibitors cause vasodilation?

A

Increased intracellular cAMP
Dephosphorylates MLCK
Smooth muscle relaxation

22
Q

What effects does pimobendan have?

A

Positive inotrope

Vasodilator

23
Q

How is pimobendan administered? Where is it metabolised/activated and excreted?

A

Oral or parenteral
Activated in liver
Excreted in faeces

24
Q

What are the side effects of pimobendan?

A

Inappetance
Lethargy
Dyspnoea
Azotaemia

25
Q

What is the effect of cardiac glycosides? What is the only one in use?

A

Positive isotropy

Digoxin (also negative chronotrope)

26
Q

How does digoxin (cardiac glycoside) work to cause positive isotropy?

A

Inhibits Na/K pump in cardiomyocytes
Increases intracellular Na, decreases Ca
Causes calcium to move to smooth reticulum

27
Q

What type of sympathomimetics are used for as positive inotropes? What other effect do they have?

A

B1 agonists e.g. dobutamine

Also positive chronotrope

28
Q

What are the adverse effects of sympathomimetics? When may dobuatmine be used?

A

Tachycardia

Anaesthesia

29
Q

What 3 dress are used as negative inotropes?

A 
Sympathetic antagonists (Beta blockers)
Cholinergic 
Calcium channel blockers
30
Q

How do cholinergics cause negative inotropy? What receptor is involved?

A

Antagonise sympathetic action on cardiomyocytes

M2 receptor

31
Q

How do calcium channel blockers cause negative chronotropy?

A

Reduce calcium influx into cell

Reduced contractility

Cardiovascular (13 decks)

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