Ischaemic Heart Disease Flashcards
Ischaemic Heart Disease
a group of clinical syndromes usually due to atherosclerosis of the coronary arteries: angina, MI, heart failure
Less common ischaemic heart diseases:
- arrhythmias
- mitral valve dysfunction
Angina symptoms and exacerbating figures:
- exertional
- settles within 2-10min
- tight/dull/squeezing/heavy
- poorly localised, L>R, commonly across the chest
- radiation to arms L>R and throat/teeth
- sometimes can be worse on inspiration but very few
- worse: in the cold, after a large meal
Demand Ischaemia:
- is (2)
- causes
- when
- stable angina
- fixed obstruction
- inadequate blood flow when demand increases:
- exertion
- other demands for blood (post-meal)
- tachyarrhthmia (increases metabolic demand,
chest pain) - will present as chest pain (angina)
Incidence of coronary artery disease by age
over 70s increased risk
Cardiac Pain:
- referred pain = pain of visceral origin, perceived in
somatic regions innervated from the spinal segments
as the heart - carried via cardiac sympathetic afferent nerves:
- to spinothalamic tract
- to the thalamus
- to the cerebral cortex
Cardiac pain referred to which areas?
- T1-T5 (chest pain)
- C5-C6 (shoulder)
- tends to SPARE C7-C8 (distal arm)
Cardiac referred pain diagram
insert
Myocardial Infarction: symptom of chest pain: key features:
- severe and persistent
- tight/dull/squeezing, heavy
- poorly localised, L>R, commonly across chest
- radiation to arms L>R and throat/teeth
Myocardial Infarction associated symptoms:
- malaise
- nausea
- breathlessness
- sweating
Myocardial Infarction is acute or chronic
acute
Supply Ischaemia:
- is (2)
- caused by
- results in
- acute coronary artery occlusion (full occlusion)
- inadequate blood flow even to cover basal
requirements - atheromatous plaque that has ruptured, exposing
collagen and proteins, activating clotting cascade,
thrombus formation, looming occlusion - results in an acute MI
Ischaemic Cascade:
insert diagram
Heart Failure:
- causes and symptoms
- Due to low cardiac output:
- fatigue - Due to fluid retention:
- leg swelling
- breathlessness (cough)
- orthopnoea
- Paroxysmal nocturnal dyspnea (waking in the
night gasping for breath) - 50-70% cases due to IHD:
- previous MIs
- chronic ischaemia
Paroxysmal nocturnal dyspnea indicates
LV systolic dysfunction
Silent Ischaemia:
- first sign of IHD may be sudden death:
- acute occlusion of non-obstructive plaques or
- obstructive disease with silent ischaemia - strong evidence of benefit from preventive
medication/therapies and lifestyle changes
Silent Ischaemia: Screening?:
- no ideal screening test
- Exercise ECG: low sensitivity and specificity, labour
intensive - Cardiac CT: expensive, radiation risk
Principles of Management for all IHD patients:
- lifestyle changes
- risk factor management
- anti-thrombotic therapy
may work:
- medication for symptoms
- revascularisation for chronic, severe disease
- acute reperfusion Rx for STE-MI
- rehabilitation
Principles of Management for IHD: Lifestyle changes:
- stop smoking
- optimise weight: MBI 18.5-25 kg/m^2
- low saturated fat diet
- regular aerobic exercises
Principles of Management for IHD: Risk Factor Management: State the three risk factors:
- hypertension
- hyperlipidaemia
- diabetes
- become younger and more female
Principles of Management for IHD: Risk Factor Management: Hypertension:
- lose weight
- reduce salt intake
- drugs (ACE inhibitors = Ramipril)
Principles of Management for IHD: Risk Factor Management: Hyperlipidaemia:
- diet: reduce saturated fat intake
- Drugs: (statins = atorvastatin)
Principles of Management for IHD: Risk Factor Management: Diabetes:
- optimise glycaemic control: reduce intake of refined
sugars - drugs (metformin, insulin)
Anti-platelet drugs:
- cyclo-oxygenase: aspirin
- ADP receptor anatagonist: Clopidogrel
- GP 2b/3a antagonists: Abciximab, Tirofiban,
eptifibatide
Anti-platelet drugs diagram
insert
Acute MI anticoagulants:
- heparin derivatives
- intravenous heparin
- low molecular weight heparin
- fondaparinux
Anti-anginals:
- beta blockers (beta 1 selective (bisoprolol))
- calcium channel antagonists (cause vasodilation)
(amlodipine, diltiazem)
-
Anti-anginals:
- beta blockers (beta 1 selective (bisoprolol))
- calcium channel antagonists (cause vasodilation)
(amlodipine, diltiazem) - Nitrates (GTN, isosorbide)
Medical Rx - Anti-anginals: beta-blockers:
- block cardiac beta-1 receptors: reduce the force of
contraction, reduce heart rate response to exercise - biosprolol (beta 1 selective)
Medical Rx - Antianginals: Calcium Channel Blockers:
- calcium channel antagonists
- reduce calcium entry to myocyte and vsacular smooth
muscle - reduce force of heart contraction
- dilate arteries: coronary arteries, lowers BP (reduced
afterload) - amlodipine, diltiazem
Medical Rx - anti-anginal drugs: Nitrates:
- nitrates mimic actions of nitric oxide (EDRF)
- dilate coronary arteries
- dilate veins > arteries, reducing venous return
(preload) - short-acting: GTN spray
- Long acting: Isosorbide mononitrate
Left anterior descending artery:%:
45%
Circumflex artery: %:
20-30%
Left mainstem and Proximal Left anterior descending:
high risk
Revascularisation: Coronary Artery Bypass Grafting:
- open heart surgery via sternotomy
- uses conduits to bypass coronary stenoses: internal
mammary arteries, radial arteries, saphenous veins - heart stopped
- bypass machine
- 1 week in hospital
- 2-4 months recovery
Revascularisation: PCI:
- percutaneous coronary intervention
- stenting, angioplasty
- percutaneous procedure:
- catheter to the coronary artery
- wire through the narrowing
- dilated with a balloon
- stent deployed - local anaesthetic
- rapid recovery
- home same day
- back to normal in 1 week
Acute MI: minutes = myocardium:
- necrosis detectable after 15min, but
- not uniform within an ischaemic territory: sub-
endocardial myocardium is more sensitive, collateral
blood vessels provide partial protection - myocardium can be salvaged upto 12 hours after
coronary occlusion
Acute reperfusion Rx for ST-elevation MI- thrombolysis vs primary PCI:
Typical STEMI mortality rates:
Pre-intervention 10-15%
Thrombolysis/aspirin 6-8%
Balloon only PCI 2-3%
Balloon + stenting PCI <1%
Why is it harder to use a saphenous vein in a CABG?
harder to make a vein behave as an artery
7% occlusion chance
