Cardiovascular Therapeutics- Anti-Arrhythmic Drugs Flashcards by Philip Meakin

What are the four classes of anti-arrhythmic drugs?

Class 1- Sodium Channel Blocker (e.g. lidocaine, flecanide)
Class 2- Beta Blocker (e.g. metoprolol)
Class 3- Potassium Channel Blocker (e.g. amiodarone)
Class 4- Calcium Channel Blocker (e.g. verapamil)

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What is the treatment for SVT?

This is a shockable rhythm- put on defib pads
Vagal manoeuvres- aim to stimulate the vagus nerve and reduce HR
Carotid sinus massage- Interpreted as HTN and so HR is reduced
Large bore cannula- give adenosine to reduce HR
If ineffective give verapamil
Shock if no improvement or haemodynamically compromised (hypotensive, going into cardiogenic shock)

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How does adenosine work?

Acts on adenosine receptors to slow the heart rate
Causes hyperpolarisation
Transient AV block

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What is a side effect of adenosine?

Feeling of death

Chest tightness, flushing

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What is a contra-indication to adenosine?

Asthma

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What are the three types of AF?

Paroxysmal- intermittent
Persistent- up to 7 days
Permanent - over 7 days

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What is the treatment for AF?

Anticoagulation- Warfarin, dabigatran, apixabam
Rate control- Beta blockers
Rhythm control- amiodarone, flecainide
(It is either rate or rhythm control)

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What are the two types of rhythm control?

Pharmacological- amiodarone, flecanide

Non pharmacological- DC cardioversion, catheter ablation

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How does digoxin work?

Inhibits sodium potassium ATPase in cardiac myocyte enzyme
This causes intracellular sodium to increase
Causes decreased activity of sodium-calcium exchanger which normally extrudes calcium
Increases in intracellular calcium causes increase in contractility
Also enhances vagal inhibition of SAN rate and AVN conduction

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Which drug can cause digoxin toxicity?

Furosemide

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What are some side-effects of digoxin?

Arrhythmias
Nausea and vomitting
Fatigue
Confusion
Reduced colour vision- xanthopsia

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What should be given in digoxin overdose?

Atropine

Digoxin specific antibody

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What are some side effects of amiodarone?

Lung fibrosis
Hepatitis
Thyroid dysfunction
Photosensitivity
Dark grey/blue skin
Tremors 
Ataxia
Corneal microdeposits

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How does flecanide work?

Slows conduction in the atria, his-purkinje system, acccesory pathways and ventricles
Sodium channel blocker

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What is the mechanism of warfarin?

Inhibits synthesis of vitamin K dependent clotting factors

Anti-coagulant effect takes several days to develop and is initially pro-coagulant

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What is the target INR for someone with AF?

2-3 (Normal is 1)

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What is the antidote to warfarin?

Give vitamin K

What juice should be avoided with warfarin therapy?

Cranberry juice should be avoided as it inhibits cytochrome p-450 which metabolises warfarin. Therefore causes INR to increase.
So does clarithyromycin, metronidazole and ciprofloxacin

What does DOAC stand for?

Direct Oral Anti-coagulant

Give an example of a DOAC

Dobigatran

How is dobigatran reversed?

This requires a monoclonal antibody called idarucizumab which is very expensive

How do statins work?

HMG CoA reductase inhibitors

Cause up-regulation of LDL cholesterol receptors and therefore remove it from the serum

What is a side effect of statin therapy?

Myalgia
Myositis
Raised LFTs
Rhabdomyolysis (rare)

What is ezetimibe?

Drug used to treat hyperlipidaemia
Blocks NPC1L1 transport protein in the brush border of enterocytes and so prevent intestinal absorption of cholesterol
Use if satins not tolerated

What are fibrates?

Lipid lowering drugs that largely reduce circulating VLDL and so triglyceride Examples include benzafibrate, fenofibrate Not for routine use

How do PCSK9 inhibitors work?

PCSK9 binds to the receptor for LDL receptor causing it to be broken down. This causes up-regulation of LDL receptors on hepatocytes resulting in increased LDL uptake from blood Monoclonal Ab that is an SC injection Example - Alirocumab and Evolocumab Expensive and only recommended by NICE for certain high risk patients

What re the four targets to treat angina?

Reduce the HR and so cardiac work Reduce TPR and so reduce the after-load Reduced venous return and so reduce preload Vasodilation of the coronary artery to increase blood supply to myocardium

How does Ivabradine work?

Slows the heart rate through inhibition of the funny current | Ivabradine is an alternative to beta-blockers if not tolerated

What is the mechanism through which nitrates work?

Decompose to NO which causes vasodilation | Increases coronary flow and reduces preload and afterload

What is a side effect of nitrates?

Headache | Postural hypotension

What conditions are included in acute coronary syndrome?

STEMI NSTEMI Unstable Angina (No trop rise)

What is the primary management for ACS?

``` Morphine Oxygen- Maintain 94-98% O2 Sat Nitrates- GTN Aspirin (300mg) and Clopidogrel Beta-blocker ACEi/ARB Statins H- Low molecular weight Heparin Also give anti-emetic metoclopramide ```

What is the treatment for MI?

``` PCI Or Thrombolysis (Alteplase)- if PCI not available ```

What is alteplase?

Alteplase is used for thrombolysis It is a tissue plasmingoen acitvator Also used for stroke and massive PE Note- Streptokinase is no longer used as it is derived from streptococcus and antibodies develop after first use. Alteplase is not antigenic

What is fondaparinux?

Unfractionated heparin- prolongs the APTT

How is fondaparinux given?

IV bolus/infusion and so acts immediately

Give an example of a low molecular weight heparin

Enoxaparin Tinazaprin Do not prolong the APTT

Give two examples of antiplatelet therapy

Aspirin Clopidogrel Tricagrelor

What is the mechanism of action of aspirin?

Inhibits COX-1 which reduces TXA2 synthesis Effects last as long as platelet lifespan Reduces platelet activation and aggregation

What are some side effects of apirin?

Upper GI bleeding | Peptic ulcers

How does clopidogrel work?

Adenosine P2Y12 inhibitor- irreversibly inhibits ADP induced platelet aggregation

How does ticagrelor work?

Inhibits ADP induced platelet aggregation | Allosteric inhibition of P2Y12 receptor