ISchaemic heart disease

Question 1

Action of nitrates

Answer 1

Release NO
Venodilation. Leads to a decrease in preload (return of blood to the heart) which reduces cardiac work (helps manage symptoms of angina)

Question 2

Action of GTN (sprayed under tongue in angina attack)

Answer 2

GTN releases NO in body which acitvates enzymes Guanylyl cyclase which increases cGMP (which then causes vasodilatation)

Question 3

What can be used for longer term prevention of angina

Answer 3

Nitrate patches/tablets

Question 4

What must you consider when using longer term nitrates

Answer 4

Prolonged exposure can reduce effectiveness therefore

• Aim for a nitrate free period (2 doses) or leave patches off for several hours
• Or use sustained release preparations which are given once daily but do not give 24h coverage

Question 5

Main drugs for prevention of angina

Mechanism of action

Answer 5

Beta blockers (e.g. atenolol)

• It is a negative inotrope which reduces the force of contraction of the heart
• It is also a chronotrope which reduces the heart rate
• Anti-arrhythmic effects and reduce the risk of MI

Question 6

When does blood flow occur

Answer 6

Diastole

Question 7

What other drugs to use for ischaemic heart disease

Answer 7

Calcium channel blockers (esp rate limiting agents)

Question 8

Mode of action of calcium channel blockers

Other modes of action of specifically verapamil

Answer 8

Vasodilatation and improve coronary blood flow

Myocardial depressant and bradycardia actions so reduce cardiac work. Also exerts an anti-arrhythmic activity

Question 9

Why are Rate limiting calcium channel inhibitors preferred in angina to DHPs

Answer 9

As DHPs can cause reflex tachycardia

Question 10

What is the mode of action of Potassium channel activators such as nicorandil

Answer 10

Combined NO donor and activator of ATP- sensitive K+ channels.

This causes K+ to leave cell which makes cell hyper polarised and so causes vasodilatation

Question 11

Mode of action of Ivabradine

Answer 11

Inhibits If channels (pacemaker Na/K currents in the SAN)

Reduces heart rate

Question 12

What are anti platelet drugs

Answer 12

Low dose aspirin

Clopidogrel

Question 13

Mode of action of clopidogrel

Why is it used

Answer 13

ADP receptor antagonist

Used in pts who cannot receive aspirin. OR used with aspirin

Question 14

What is clopidogrel contraindicated with

Answer 14

Omeprazole

Question 15

What to do when a patient presents with angina

Answer 15

GTN for relief

Then assess CV risk. IF high, then give

• lifestyle advice
• Aspirin or clopidogrel
• Statin
• BP controlled to <140/85

Question 16

What is used as a preventative method

Answer 16

Beta blocker+/- oral nitrate

Or

calcium channel blocker +/- oral nitrate if beta blocker contraindicated

Question 17

What to use if IHD is not being managed by a beta blocker or a calcium channel blocker

Answer 17

Use a calcium channel blocker or a beta blocker. but the calcium channel blocker MUST be a DHP (not a Rate limiting as this is fatal)