Ischaemia Flashcards
What are the three treatment goals of treating stable angina?
- address the pain
- reduce myocardial oxygen demand
- address modifiable CV risk factors
What is the first line therapy for acute angina?
Nitrates.
Why is GTN only available as a spray, sublingual or patch?
Too much first-pass metabolism for oral route.
Why do nitrate users need to take 10-12h breaks and not take them at night?
Because really fast tolerance is rapid in organic nitrates.
Which nitrate has the longest half life and is best suited as a prophylactic?
isorbide mononitrate.
Why is the sublingual isorbide dinitrate dose so much lower than the oral?
Because of low bioavailability the dose needs to be increased significantly.
What nitrate would you use when the angina is getting unstable and you need to get serious?
GTN.
GTN is a prodrug to what?
Nitric oxide (NO)
What does endogenous nitric oxide increase?
cGMP
What does the secondary messenger cGMP activate?
Myosin light chain kinase
What does the effector myosin light chain kinase do?
It relaxes smooth muscle.
What are the main side effects of nitrates
postural hypotension and headaches.
What beta receptor does the sympathetic act through on the heart? What’s the other location?
B1 Kidney (stimulation = renin release)
Which beta receptor is responsible for bronchodilation and arteriolar dilation?
Beta2
What’s one main reason you’d prefer B1 selectivity in coronary ischaemia?
B2 receptors are in arterioles and stimulation triggers dilation- you don’t want arteriolar dilation because vascular steal.
What is a characteristic beta blocker effect?
What’s a possible long term safety issue?
Cold extremities.
May aggravate peripheral arterial disease.
Does B1-selectivity decrease with dose?
Yes.
What are four options for stable angina?
Nitrates
Beta blockers
CCBs
Antiplatelets
Why aren’t ACEIs really in the stable angina toolkit?
Because they don’t affect heart exertion much.
Why would antiplatelet drugs be on there when there’s no thrombus?
Because we wanna prevent the thrombus from happening. The other anti-clotting drugs are much more a response to an existing clot.
Many stable angina patients are old dudes. What do you have to watch out for as contraindicated for nitrates?
viagra [in the last five days]
What are the typical choices for antiplatelets for stable angina?
aspirin or clopidogrel
What are four ways you can limit irreversible ischaemic damage?
Oxygen tube
Anti-clot
Opioids (pain relief + decrease sympathetic drive)
Beta blockers or ACEI.
