Drugs for IHD Flashcards
What is O2 supply dependent on?
- Whether coroanry blood flow is adequate
- O2 carrying capacity of blood
- Anatomy of coronary arteries (lumen size-affected by atherosclerosis)
What is O2 demand affected by?
- Preload & afterload
- Wall thickness
- Contractility and heart rate
- Left ventricular volume and diameter
What causes ischaemia?
Inadequate coronary blood flow
What are the IHD categories?
-
Chronic coronary artery disease (CAD)
- Stable Angina
-
Acute coronary syndromes
- Unstable angina
- NSTEMI (Non-ST elevation MI; subendocardial)
- STEMI (ST-elevation MI; transmural)
What is a myocardial infarction?
A damaged area of heart muscle resulting from a sustained block of coronary blood supply by a thrombus
Which serum proteins are used to indentify MI?
- 1-2 hours post MI: Elevated myoglobin
- 2-4 hours: elevated Troponins, CK-MB
- 3-6 hours: CK-MB
CK-MB levels peak after 24 hours, whereas troponin keeps building up then decreases just before 48 hours post MI
How does a transmural MI cause sudden death?
- Transmural MI results in patches of necrotic/ apoptotic tissue failing to conduct wave of depolarisation.
- this produces Q wave (ST) changes
Whatare the symtpoms of MI?
- Central chest pain radiating to neck and arms
- not relieved by sublingual GTN
- Shortness of breath, nausea
- High pulse rate
What should you first aim to do after an MI like presentaion?
- Aim to re-establish O2 supply. We can do this by increase the duration of diastole (using a beta blocker), and by decreasing coronary resistance.
- And we need to decrease myocardial O2 demand (MVO2) to prevent more ischaemia and necrosis.
When we used drugs that wil reduce preload, what physiological effects does this have?
We reduce preload by Increasing peripheral venodilaton, decreasing venous return allowing a reduction in end diastolic volume and improved coronary perfusion.
When we use drugs to reduce afterload, what physiological effects does this have?
By reducing BP or decreasing peripheral arteriolar resistance
When treating acute coronary syndrome we do MONA what does this mean?
MONA
- Morphine - reduce pain & anxiety
- May need to give antiemetic (metoclopramide)
- Oxygen - only use if O2 sats below 90
- Nitroglycerin - S/L or spray, if pain unresolved use morphine to relieve pain if no asthma/COPD (can get respiratory depression)
- Aspirin
- high dose initially, then low dose daily
After how long does irreversible loss of myocardial tissue occur?
After 45 mins of ischaemia
Death common within first 2 hours following symptoms
What 3 classes of drugs should be give to improve symtpoms in MI patients quickly and to reduce their pain?
- Morphine
- Nitrates
- Low dose aspirin
Why are nitrates (GTN) given for IHD?
Nitrates decrease myocardial demand
they release NO causing vasodilation and venodilation, which decreases preload and afterload. (It’s primarily venous dilation but also does arterial dilation).
- The venodilation decreases venous return/preload (improves diastolic duration and subendocardial perfusion.
- The vasodilation on the arterial system decreases afterload.
Summary of management of acute MI
What is does tenecteplase do for patients with MI?
Its purpose is to acutely destroy (lyse) or prevent thrombus formation that occurs within the coronary artery at the time of myocardial infarction.
(Facilitates the coversion of plasminogen to plasmin)
Should be used acutely within 12 hours from onset of ischaemia if no prior contraindications
Effects of statins?
What are the effects of ACE inhibitors?
How is stable angina managed?
Which drugs are used for the management of stable angina?
What is the pharmacological management of untable angina and NSTEMI?
