Coronary Artery Disease Flashcards
Risk factors for atherosclerosis
Smoking, hypertension, hyperlipidaemia, diabetes, age, sex (male), genetics
Pathogenesis of atherosclerosis
Primary endothelial injury → accumulation of lipids and macrophages → migration of smooth muscle cells → increase in size
What do atheromas look like?
Pale, yellow, porridge like sludge in the artery walls
Earliest sign of accumulation of atheromatous plaques
Fatty streaks
Progression of atheromatous plaques
Fatty streaks, fibrofatty plaque, complicated plaque
When is atheromatous narrowing of an artery likely to produce critical disease? (3)
- If it is the only artery supplying an organ or tissue
- If the artery diameter is very small
- Overall blood flow is reduced
Complications of atheroma (5)
Arterial stenosis, thrombosis, aneurysm, dissection, embolism
Aneurysm definition
Abnormal and persistent dilatation of an artery due to a weakness in its wall
Most common site for aneurysm
Abdominal aorta
Types of aneurysm
Mycotic, atherosclerotic, dissecting, congenital, arteriovenous, traumatic, syphilitic
Complications of aneurysm
Rupture, thrombosis, embolism, pressure erosion of adjacent structures, infection
Dissection definition
Splitting within the media by flowing blood (artery splits in 2 with normal in the middle and another lumen all the way round)
Risk factors for and associations with dissection
Middle age +/- atheroma
Atheroma, hypertension, trauma, coarctation, marfan’s, pregnancy
Usual targets for embolism
Cerebral infarct, renal infarct and renal failure, lower limb infarction
Clinical effects of cardiac ischaemia
Reduced exercise intolerance, angina (stable and unstable), myocardial infarction, cardiac failure
What does cardiac fibrosis result from?
Loss of cardiac myocytes and replacement by fibrous tissue
Complications of arterial stenosis in the carotid artery
TIA, stroke, vascular dementia
Complications of arterial stenosis in the renal arteries
Hypertension and renal failure
Complications of arterial stenosis in the peripheral arteries
Claudication and foot/leg ischaemia
Clinical effects of thrombosis
MI, cerebral infarction, renal infarction, intestinal infarction
Chronic stable angina
Fixed stenosis within a coronary artery. There is demand led ischaemia, it is predictable and causes safe symptoms. Patients advised to stop, rest, and use GTN spray
Cardiac chest pain
Nature of heavy feeling, weight on the chest, pressure, tightness. Centre of the chest radiating into the jaw and into the left arm.
Continuum of acute coronary syndrome
Asymptomatic → stable angina → unstable angina → acute non STEMI and non-Q wave, sub-endocardial MI → STEMI and AMI Q wave MI
What is the hallmark of coronary syndromes
Going from stable to unstable
Factors affecting plaque rupture/fissure
Lipid content of plaque, thickness of fibrous cap, sudden changes in intraluminal pressure or tone, bending and twisting of an artery during each heart contraction, plaque shape, mechanical injury
3 steps in the platelet cascade
Initiation, adhesion, activation
What happens in the initiation stage of the platelet cascade?
Vascular damage causes exposed tissue elements, including subendothelial collagen
What happens in the adhesion stage of the platelet cascade?
Platelet recruitment and adhesion at the site of injury forming a monolayer
What happens in the activation stage of the platelet cascade?
There is a release of activators through degranulation (e.g. ADP), which bind to surface receptors, affecting circulating platelets. Platelet activation accelerates and results in platelet aggregation. Activation of platelets also triggers the inflammatory cascade and an organised fibrin-rich thrombus forms
ECG changes in acute STEMI
≥ 1mm ST elevation in 2 adjacent limb leads or ≥ 2mm ST elevation in at least 2 continuous precordial leads, T wave inversion sometimes, Q waves sometimes
Evolving ECG changes of acute MI
ST elevation – first few hours
Q wave formation and T wave inversion – first day
Q waves +/- inverted T waves – ‘old MI’
Protein marker used in MI
Troponin - highly specific for cardiac muscle damage
Differentiation of angina attack vs acute MI:
- Duration
- Onset
- Severity
- GTN
- Associated symptoms
- Duration - angina = 10 mins, MI = 30 mins or longer
- Onset - angina = on exertion, MI = at rest
- Severity - angina = usual pain, MI = severe
- GTN - angina = relief, MI = no effect
- Symptoms - angina = usually none, MI = sweating, nausea and vomiting
Early treatment in STEMI
M - morphine (with anti-emetic) O - oxygen if hypoxic N - nitrates A - aspirin (300mg and chewed to increase surface area) T - ticagrelor or clopidogrel
Indications for reperfusion therapy (thrombolysis or PCI)
Chest pain suggestive of MI that has been going on for > 20 mins but <12 hours, ECG changes relating to MI, no contraindications
Risks of thrombolysis therapy
Failure to reperfuse, haemorrhage, hypersensitivity
When is PCI used to treat MI
Better to treat MI but must be given within 120 minutes
Complications of acute MI
D - death A - arrhythmia R - rupture T - tamponade H - heart failure V - valve disease A - aneurysm of ventricle D - Dressler's syndrome/depression E - embolism R - mitral regurgitation
Non ST elevated myocardial infarction
Unstable coronary syndrome caused by dynamic narrowing of the artery
Pathogenic trigger for NSTEMI
Spontaneous platelet rupture
Score for identifying high risk patients suffering from NSTEMI
GRACE score
Coronary revascularisation technique
Advance a guidewire past the blockage, the balloon is passed over and is inflated which breaks up the plaques, the stent is embedded into the vessel wall and this plasters down the plaque and increases blood supply and makes stasis and clotting less likely.
Troponin-itis
A condition leading to a misdiagnosis of acute coronary syndrome based only on a troponin elevation
Conditions other than MI where troponin is elevated
Heart failure, hypertensive crisis, renal failure, PE, sepsis, stroke, pericarditis, post arrhythmia
Factors relating to type II myocardial infarction
Secondary to ischaemic imbalance, increased myocardial oxygen demand, decreased myocardial oxygen/blood flow
Type I vs type II MI:
- Chest pain
- ECG changes
- Cause
- Troponin
- Coronary artery disease
- Chest pain - Type I = sudden symptoms, Type II = less chest pain
- ECG changes - Type I = major ECG changes, Type II = minor ECG changes
- Cause - Type I = no obvious cause, Type II = tachycardia/low BP/illness
- Troponin - Type 1 = higher trop with rise then fall, Type II = smaller more static trop
- CAD - Type I = severe CAD, Type II = mild to moderate CAD
Conditions associated with non-ischaemic myocardial injury with necrosis
Cardiac contusion, ablation, pacing, AICD shocks, myocarditis, cardiotoxic chemotherapy, severe sepsis or respiratory failure, PE, pulmonary hypertension, chronic severe heart failure, chronic renal failure, severe acute neurological diseases e.g. stroke, exercise, burns, stress cardiomyopathy
Secondary prevention for MI
Healthy lifestyle, smoking cessation, good control of BP, cholesterol and diabetes
4 phases of cardiac rehab
Phase 1 = inpatient
Phase 2 = early post discharge period
Phase 3 = structured exercise programme
Phase 4 = long-term maintenance of physical activity and lifestyle change
Drugs given in the Cath lab to treat MI
Heparin intra-arterially, atropine if bradycardic, adrenaline if things not going right, nitrate, verapamil, group IIb/IIIa inhibitors
Why is heparin given in the Cath lab?
To prevent clots from forming around the equipment
Dose of heparin given in Cath lab
100mg/kg
Why are nitrates given in the Cath lab?
To vasodilate the arteries, and radially to prevent spasm of radial artery
Why is verapamil given in the Cath lab?
Causes relaxation of the radial artery to prevent spasm
Drug treatment in thrombolysis
Tenecteplase (usually used), alteplase, reteplase, aspirin and clopidogrel, exoxaparin
Absolute contraindications for thrombolysis
Previous intracranial haemorrhage or unknown stroke, ischaemic stroke <6 months, CNS damage, arteriovenous malformation, major trauma/head injury/surgery
Relative contraindications for thrombolysis
TIA <6 months, oral anticoagulant therapy, pregnancy or 1 week postpartum, refractory hypertension, advanced liver disease, infective endocarditis, active peptic ulcer, prolonged or traumatic resuscitation
Risks for hazards in thrombolysis
Female, advanced age, lower weight, previous cerebrovascular disease, systolic and diastolic hypertension
Immediate management of NSTEMI
Morphine + anti-emetic, oxygen , nitrates, aspirin
Drugs given on admission with NSTEMI
Ticagrelor/clopidogrel, beta blocker if haemodynamically unstable, fondaparinux
Medications on discharge for people suffered MI
Aspirin, clopidogrel/ticagrelor/prasugrel, bisoprolol, ramipril or ACE inhibitor, eplerenone, statin (usually atorvastatin)
Risks with prescribing aspirin
Can cause stomach ulcers, people are allergic
Side effect of ticagrelor
Dyspnoea
When is prasugrel contraindicated?
Previous stroke/TIA, not recommended in >75 years or low weight
