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Cardio 4 > Arrhythmai therapies and drugs > Flashcards

Arrhythmai therapies and drugs Flashcards

1
Q

What is the Vaughan-Willians classifications of anti-arrhythmic drugs?

A

C;lasses antiarrythmic drups 1-5 in relation to the receptor they work on

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2
Q

Why are anticoagulants important in cardiac arrythmias?

A
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3
Q

What is sinus arrythmia?

A

It is the natural increase and decrease ib heart rate, especially in younger people when they breathe in and out (increased HR on inhalation, and decreased HR on exhalation)

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4
Q

Supraventricular arrhythmias eg and ecg

A

AF, SVT (junctional)

Narrow QRS complex, genararlly more irregular (esp tchycardias)

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5
Q

ventricular arrythmias eg and ecg

A

Ventricular tachycardia, Ventricular fibrillation

ecg = broad complex, more radid regular (esp tachycardias)

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6
Q

What is bradycardia (pathologies)

A

30-40bpm

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7
Q

resting pot. of heart?

A

-90mV

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8
Q

What do class 1 anytiarrythmias work on?

A

Sodium channels (blockers), therefore reducing the size of action potential (amplitude), also reduces the velocity of conduction and excitability.

Split into
Ia moderate
Ib weak
Ic - strong eg flecainide

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9
Q

Class 2 are? Act on?

A

Betablockers, act on B1 receptors on the heart, blocking sypathetic stimulisation:

  • prolongs depolarisation (reduces SA node and AV conduction, reduces excitability in non nodal cardiac tissue)
  • weaker contractions as shortens phase 2
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10
Q

Class 3?

A

Potassium channel blockers
Blocks K+ channels so delays repolarisation, increasing AP duration

Used fro hard to treat dysrhythmias

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11
Q

Class 4?

A

Ca+ (L type) channel blockers

depresses depolarisation and so slows heart rate in all heart, reduces contractility.

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12
Q

Class 5?

A

Other

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13
Q

What type of drug s Flecainide?

A

A strong Na+ channel blocker, class 1

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14
Q

What type of drug is Atenolol?

A

Beta blocker - used more for bp, class 2

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15
Q

What type of drug is Bisoprolol?

A

Beta blocker - used more for rate control class 2

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16
Q

What type of drug is Amiodarone?

A

K+ channel blockers, class 3

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17
Q

What type of drug is Diltiazem?

A

Ca2+ L type channel blockers, class 4

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18
Q

What type of drug is Verapamil?

A

Ca2+ L type channel blockers, class 4

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19
Q

What type of drug is Digoxin?

A

“Other” class 5

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20
Q

How do class I drug works?

A

Block Na+ channels and therefore decrease the rate and strength of action potential. Repolarising remains unaffected and occurs at the same time and rate as normal.

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21
Q

How does Flecainide affect the depolarisation and repolarisation of cardiac cycle?

A

Flecainide is a class Ic, so a strong Na+ channel blocker, therefore depolarisation is much slower and not as strong. The repolarising phase is pretty much unaffected.

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22
Q

How do class II work?

A

Beta blockers, block B1 receptors on heart so block the affects of the sympathetic stimulation of the heart.

Leads to longer depolarisation and shorter contraction

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23
Q

What is first line control of AF?

A

Bisoprolol

24
Q

How do class III work?

A

Block K+ channels and so prolong repolarisation and increase AP duration. Alos prolongs ERP.

25
Q

Class III used for what?

A

Hard to treat dysrhythmias.

Ventricular tachycardia or fibrilation, AF or atrial flutter

26
Q

WHat do you do to verapamil/digoxin if startingf Amioadrone?

A

Half the dose as they compete with Amiodrone for albumin binding

27
Q

What abnormalities can Amidraonone toxcitiy cause?

A

Iodine - thyroid issues
Lung fibrosis
Sun damage leads to permanent slate grey pigmentation
Eye deposits

28
Q

How do class 4 work?

A

Block type L Calcium channels, so slows th edepolarisation meaning reduced heart rate and also strength of contraction.

Used for paroxysmal supraventricular tachycardia, rate control of AF and atrial flutter

29
Q

What type is adenosine?

A

An “other” drug, type 5

30
Q

What does Digoxin do?

A

Inhibits sodium-potassium ATPase pump.

Slows HR (decreases vagal tone)
Reduces refractory period
Increases intracellular Ca
31
Q

Digoxin indications

A

Atrial dysrhythmias eg AF, Atrial Flutter, (SVT)

Heart failure

32
Q

Digoxin half life and factors affecting, and symptoms

A

Long! 36-48h!

Kidney function affects half live and also digoxin affects kidney life!

Monitor for toxicity

Nausea and vommiting, yellow haze around everything (Xanthopsia), brady and tachycardia, VT and VF arrhythmias

33
Q

How to reduce digoxin levels if become toxic?

A

Digibind, forms an immune complex , that is more easily secreted.

34
Q

How does Adenosine work and use?

A

Blocks/slows conduction through AV node. Converts paroxysmal supraventricular tachycardia to sinus rhythm.

35
Q

Adenosine short/long half life? Symptoms?

A

Short half life, minimal side effects- can cause arrhythmias.

36
Q

AF has what significant srisks?

A

Stroke

37
Q

Why AF cause thrombosis?

A

The disarray of atrial contraction can lead to stasis, particularly in the left atrial appendage.

Also due to increase in size of the atrium.

38
Q

Prevelance of AF?

A

Increases with age, 10-20% 8th decade have some af

39
Q

2 other important risk factors

A

Other medical contitions, BP and diabetes

40
Q

CHADSVascS score means what ?

A 
C - congestive heart failure (1)
H - Hypertension (1)
A - Age (65-74 =1, 75+ = 2)
D - Diabetes
S - Stroke/Tia/thromboembolism (prev) - (2)
Vasc - Vascular disease (1)
Sex - femaie (1)

Increase in score means higher risk of stroke.

2+ = moderate -high risk, consider anticoagulant. 
1= think about
41
Q

What makes an anticoagulant good?

A 
Minimal interactions with other drugs/food
No need for monitoring
As effective and safer than warfrin
Oral 
Given once or twice a day, fixed dose
42
Q

What 3 groups of anticoagulants ?

A

Vit K antagonists (warfrin)

Direct Thrombin Inhibitor (prevents fibrinogen to fibrin) eg Dabigatran

Direct Xa inhibitors , prevents prothrombin to thrombin) (Rivaraxaban,Apixaban, Edoxaban)

All work on the cascade of events leading to thrombin production, just at different sages.

43
Q

What type of anticoagulant is Warfrin?

A

Vitamin K inhibitor, Vit K is important in the production in clotting factors 2,7,9,10.

44
Q

What type of anticoagulant is Dabigatran?

A

Direct thrombin inhibitor

45
Q

What kind of anticoagulants are Rivaroxaban,Apixaban,Edoxaban?

A

Direct Xa inhibitors (prevents prothrombin to thrombin)

46
Q

What are the issues of warfrin?

A

Narrow therapeutic index.
No standard dose, depends on no. factros of patient so needs lots of monitoring.

Bleeding, and interacts cytochrome P450

47
Q

What is INR? What is it used to monitor?

A

International normalised ratio:

Actual PROTHROMBIN time/Standard PROTHROMBIN time

Normal is 1, therapeutic range for INR is 2.5-4 depending on clinical indication

48
Q

What anticoagulant used in pregnancy?

A

Heparin (sub cutaneous or IV)

49
Q

What is used to calculate risk of bleeding?

A

HAS-BLED Score

Hypertension (1)
Abnormal kidney(1), liver(1)
Stroke (1)
Bleeding(1)
Labile (easily changed) INRs(1)
Elderly (65+ = 1)
Drugs/Alcohol (1)
50
Q

Are falls in the elderly a contraindication for anticoafulanet?

A

Not usually , studies have shown that you’d have to be falling several times/day to sustain a major complication

51
Q

What drugs can increase warfrin activity?

A

Any drug displacing it from albumin binding site (Asprin (300mg+), sulfonamides)

Drugs inhibiting degradation - Cytochrome P450 inhibitors (cimetidine,erthyromycin)

Drugs decreasing synthesis of clotting factors (antibiotics - oral)

52
Q

What other drugs would also promote bleeding?

A

Asprin (inhibits platelets), Heparin/antimetabolites (inhibits clotting factors)

53
Q

What other drugs decrease warfrin activity?

A

Any cytochrome P450 induces (increases the removal of and excretion of warfrin)
eg barbiturates,phenytoin

Drugs promoting clotting factor synthesis (eg Vit K)

Drugs with reduced absorption (eg Cholestyramine)

54
Q

Cytochrome P450 Inhibitors

A

Decrease the metabolism of warfrin therefore increasing its effects.

Omeprazole
Disulfiram
Erythromycin, clairithromycin
Valproate
Isoniazid
Ciprofloxacin and Cimetidine
Ethanol (acutely)
Sulphonamides
55
Q

Cytochrome P450 inducers

A

ABC PRS

Alcohol (chronic use)
Barbiturates
Carbamazepine
Phenytoin
Rifampicin
Sulphonylureas
56
Q

Metallic heart valves, what anticoagulant?

A

Warfrin

57
Q

DVT/PE put on anticoagulant?

A

yes

Cardio 4 (6 decks)

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