27. SIDH (stable ischaemic heart disease) and Angina therapy Flashcards
What are 2 main types of ischaemic heart disease?
- Acute Coronary Syndrome
2. Chronic or Stable Ischaemia
What are 2 main acute coronary syndromes?
- Myocardial infarction (STEMI or NSTEMI)
2. Unstable angina pectoris
What are 2 main chronic or stable ischaemia conditions?
- angina pectoris (stable)
2. silent ischaemia
What are main risk factors for ischaemic heart disease? (6)
- hypertension
- smoking
- hyperlipidaemia
- hyperglycaemia
- male
- post-menopasusal females
What is the difference between stable and unstable angina?
- Stable angina is much more chronic, mainly on exertion or after doing a particular activity, much more controlled
- Unstable angina often occurs unexpectedly, worsening of symptoms occur, becoming more frequent and less exertion required (sometimes at rest), should be immediately treated as it’s emergency
What is the purpose of drug treatment for stable ischaemic heart disease? (5)
- to relieve symptoms
- to halt the disease process
- regression of the disease process
- to prevent MI
- to prevent death
What is hyperlipidaemia?
- disease of MUSCULAR arteries (not veins)
- mainly disease of coronary and cerebral vessels
- progressive deposition of cholesterol esters
What does hyperlipidaemia present itself at the start as?
as atherosclerosis
What does:
- ischaemic heart disease
- cerebrovascular disease
cause which can cause death?
-ischaemic heart disease causes MI
- cerebrovascular disease causes stroke
(which can both be fatal)
What are the 2 main stages of plaque formation in atherosclerosis and when do they appear?
- lesions appearing as fatty streaks (aged approx. 20 years)
- fibrous plaque (more advanced stage of disease)
What are the features of fatty streak lesions? (1)
- subendothelial accumulation of large foam cells which are derived from macrophages and SM cells filled with lipid
What are the features of fibrous plaques?(4)
- more advanced and main cause of disease
- develop from fatty streaks
- projects into arterial lumen
- cause reduction in blood flow
In which layers of the artery do most changes occur which lead to plaque deposition?
in the intimal layer
Accumulation of what cells occurs in the intimal layer of arteries that lead to plaque formation? (4)
accumulation of monocytes, lymphocytes, foam cells and connective tissue
What is the origin of most foam cells?
most are of smooth muscle origin
What are 2 “part” of an atherosclerotic plaque?
- necrotic core
2. fibrous cap
What results in stable ischaemic heart disease?
Arises as a result of MISMATCH between myocardial blood/ oxygen supply and demand
What induces and stimulates attacks of angina (chest pain) in stable ischaemic heart disease?
- Any stress or exertion which increases cardiac work and myocardial oxygen demand
- Any activity that increases heart rate, stroke volume and blood pressure
What is the relationship between O2 supply and O2 demand and myocardial ischaemia?
decrease ratio of O2 supply: O2 demand leads to myocardial ischaemia
What can cause demand ischaemia?
-ischaemia during stress (physical or emotional)
What can cause supply ischaemia?
ischaemia at REST
What are the determinants of demand ischaemia? (4)
- heart rate
- systolic BP
- myocardial wall stress
- myocardial contractility
What are the determinants of supply ischaemia? (4)
- coronary artery diameter and tone
- collateral blood flow
- perfusion pressure
- heart rate (duration of diastole)
How many types of atherosclerotic lesions are there?
6 main types
What is Type 1 atherosclerotic lesion?
- coronary artery is at lesion-prone location
- adaptive thickening of smooth muscle in the intima layer
What is Type 2 atherosclerotic lesion?
- macrophage foam cells begin to accumulate
What is Type 3 atherosclerotic lesion?
- preatheroma formed (fatty streak)
- small pods of extracellular lipid
What is Type 4 atherosclerotic lesion?
- atheorma established
- core of extracellular lipid
What is Type 5 atherosclerotic lesion?
- fibroatheroma
- fibrous thickening of atheroma
What is Type 6 atheroscletotic lesion?
- complicated lesion
- thrombus likely
- fissure and haematoma into plaque common
How do drugs helps with ischaemic heart disease? (2)
- Drugs DECREASE myocardial oxygen demand by reducing cardiac workload;
- reduce heart rate
- reduce myocardial contractility
- reduce afterload
AND - increase supply of O2 to ischaemic myocardium
What are the main RATE LIMITING drugs for ischaemic heart disease which reduce heart rate? (3)
- Beta adrenoceptor antagonists
- Ivabradine
- Ca channel blocker
What are the main vasodilator drugs used for ischaemic heart disease? (2)
- Ca channel blockers
2. Nitrates (oral or sublingual)
What are other medication which are not necessarily rate limiting or vasodilators but are also used to treat ischaemia? (3)
- K channel blockers
- Aspirin/ Clopidogrel/ Ticagrelor (first is aspirin and others used if patient allergic or intolerant)
- Cholesterol lowering agents (HMG CoA reductase inhibitors, fibrates)
What 2 Beta Blockers are used to treat ischaemic heart disease? (2)
- Bisoprolol
- Atenolol
What are beta blockers?
Reversible antagonists of the Beta 1 and Beta 2 receptors
What do newer beta blockers do? (how to they act?)
- they are cardioselective acting primarily on Beta 1 receptors
- these agents block the physiological responses to adrenaline and noradrenaline (sympathetic nervous system)
What are 3 major determinants of myocardial oxygen demand?
- heart rate
- contractility
- systolic wall tension
Why do Beta blockers allow improved perfusion of the subendocardium?
By increasing diastolic perfusion time (if heart relaxed for longer then more blood flows into myocardium)
What is the function of beta blockers in terms of cardiac function? (6)
- decrease heart rate
- decrease force of myocardial contraction
- decrease cardiac output
- decrease velocity of contraction
- decrease blood pressure
- protect cardiomyoctes from oxygen free radicals formed during ischaemic episodes
How do beta blockers act?
- reduce heart rate, reduce force of contraction and reduce blood pressure
- increase exercise threshold at which angina occurs and so move balance point at which demand for O2 outstrips the supply of oxygenated blood
- threshold reset at which angina starts
What are the main drugs used as SECONDARY prevention of cardiovascular disease? (4)
- aspirin (75mg daily)
- ACE inhibitor (for stable angina and diabetic patients)
- Statin treatment
- High BP treatment
What is meant by a rebound phenomena?
- sudden cessation/ stopping of beta blocker therapy may cause MI
- never stop beta blockers immediately (unless emergency), but instead gradually
Who is at risk for a rebound phenomena? (2)
- men over 50 receiving beta blocker treatment for other reasons
- patients with angina
What are contraindications for the use of beta blockers? (When would we NOT use Beta Blockers as a treatment option) (5)
- asthma
- peripheral vascular disease (relative contraindication)
- Raynauds Syndrome
- Heart failure (dependent on sympathetic drive)
- Bradycardia or Heart block patients (if Beta blockers over done)
What is Raynauds Syndrome?
- medical condition which causes spasm of arteries
- leads to reduced blood flow
- occurs typically in fingers (but can also happen in toes)