8. Myocardial ischaemia

Question 1

What is stable angina

Answer 1

Caused by lack of oxygen supply, typically triggered by exertion or emotional stress.

During times of exertion or emotional supply, the oxygen demand increases, however this cannot be met due to atherosclerosis inhibiting normal movement of blood cells through arteries

Question 2

Stable angina symptoms

Answer 2

• chest pain - tight, dull, heavy
• Pain radiating to left arm, neck, jaw

Question 3

Drugs to manage angina

Answer 3

Short-acting nitrate
* glyceryl trinitrate - sublingual, expired 8 weeks after opening
* isosorbide dinitrate

Long-acting nitrate
* Glyceryl trinitrate - transdermal
* Isosorbide dinitrate MR - lasts 12 hours; BD
* Isosorbide mononitrate - MR OM

Beta-blocker

Calcium-channel blocker

Vasodilator
* ivabradine
* ranolazine
* nicorandil

Question 4

Treating angina - acute attack

Answer 4

Treatment is split into acute attacks and prevention

Acute attacks:
Sublingual glyceryl trinitrate - lasts 20-30 minutes
Should be taken during acute attack or before activities that are known to cause symptoms

Sit down place 1 dose under the tongue. Repeat every 5 minutes.

If symptoms do not resolve after 3 doses, DIAL 999 = MEDICAL EMERGENCY as it may be unstable angina or a heart attack

In practice ambulance usually called after 2nd dose, 3rd dose is taken

Question 5

Angina treatment prevention

Answer 5

1st line: Beta-blocker
Reduces heart’s workload and therefore oxygen demand, through reducing the heart rate

Alternative: rate-limiting calcium-channel blocker (verapamil, diltiazem)

2nd line: Beta-blocker + calcium-channel blocker (rate-limting or dihydropyridines licensed)

AVOID beta blocker + verapamil = heart failure BIG INTERACTION

• If beta-blocker OR calcium-channel blocker cannot be given:
  vasodilator can be added as dual therapy such as a long-acting nitrate
• If both beta-blocker AND calcium-channel blocker cannot be given:
  vasodilator can be used as monotherapy such as long-acting nitrate ivabradine, ranolazine, nicorandil

Question 6

Nitrates are a

Answer 6

Potent coronary vasodilator

Question 7

Nitrate-free periods

Answer 7

Patients on long-acting or transdermal nitrates quickly develop tolerance. To maintain effectiveness, must have nitrate free periods

• Patches should be left off for 8-12 hours (glyceryl trinitrate)
• If the nitrate is BD, take the second dose after 8 hours, not 12 hours
  Isosorbide dinitrate MR (BD), Isosorbide mononitrate BD
• Take modified-release isosorbide mononitrate OD

Question 8

Nitrates side effects

Answer 8

• Flushing
• Throbbing headache
• Postural hypotension -> leads to dizziness, fainting in elderly patients

Question 9

Nitrates interactions

Answer 9

• Interacts with drugs that ALSO cause hypotension
  e.g Phosphodiesterase-type 5 inhibitor - sildenafil

ACE inhibitors, alpha-blockers beta-blockers, CCB’s, antidepressants, anti-parkinsonian drugs, anti-psychotics, diuretics, SGLT2 inhibitors

Question 10

Acute-coronary syndrome

Answer 10

Medical emergency

Unstable angina - atherosclerotic plaque ruptures in the coronary artery

STEMI - atherosclerotic plaque ruptures and blood clot forms over rupture - can lead to long-term complications

N-STEMI - atherosclerotic plaque ruptures in the coronary artery

Question 11

Acute coronary syndrome treatment - long term

Answer 11

Unstable angina, Non-STEMI
* Low-dose aspirin + high-intensity statin
* Clopidogrel (12 months)
* Anti-angina drug

STEMI
* Low-dose aspirin + high-intensity statin
* Clopidogrel
* ACE-inhibitor
* Beta-blocker

Question 12

Acute coronary syndrome treatment - short term

Answer 12

Unstable angina, Non-STEMI
* Aspirin 300mg chew or disperse in water
* Glyceryl trinitrate S/L prn

STEMI
* Aspirin 300mg chew or disperse in water
* Glyceryl trinitrate S/L prn
* IV diamorphine/Morphine + metoclopramide
* Oxygen

M - morphine
O oxygen
N - nitrate
A - aspirin

STEMI

Question 13

Percutaneous coronary intervention

Answer 13

A stent is inserted into the coronary artery to open it up and allow blood to flow more freely

Dual antiplatelet therapy should be offered to prevent a blood-clot forming on the stent:
* Aspirin (indefinitely)
* Clopidogrel (stable angina)

-Bare-metal stent: 1 month
-Drug-eluting stent: 6 months (greater risk of thrombosis with these stents)

Question 14

Cardiac arrest

Answer 14

Cardiac arrest occurs when the heart suddenly stops beating and stops pumping blood around the body = SERIOUS MEDICAL EMERGENCY

Question 15

Cardiac arrest signs

Answer 15

• Loss of consciousness
• Not breathing

Question 16

Cardiac arrest management

Answer 16

• CPR (30 chest compressions followed by 2 rescue breaths, compressions should be repeated at a rate of 100-120x/minute)

Usually given in ambulance:

• IV adrenaline - sympathomimetic, increases heart rate and force of contraction
• IV amiodarone- for pulseless ventricular tachycardia, for ventricular fibrillation

Question 17

How long should the GTN tablets be discarded after use?

Answer 17

After 8 weeks