MI 1 + 2 Flashcards
Risk factors for MI? (10)
- Smoking
- Alcohol
- Drug abuse
- Age
- Gender - male
- Stress
- Hypertension
- High cholesterol
- Obesity
- Family history
Features of chronic stable angina? (4) Treatment? (3)
- fixed stenosis
- demand led ischaemia
- predictable
- safe
Treatment
- Stop
- Sit
- Spray - GTN
Common descriptions of cardiac chest pain? What is acute coronary syndrome? What conditions does acute coronary syndrome include?
- Heavy feeling, weight on chest, pressure, tightness
- Any acute presentation of coronary artery disease - only a provisional diagnosis that covers a spectrum of conditions
- Unstable angina, acute NSTEMI, STEMI
Types of acute MI? (2)
- STEMI and NSTEMI
Pathogenesis of acute coronary syndromes?
Key pathogenic process that leads to ACS is spontaneous plaque rupture
Features of acute coronary syndrome? Examples?
* dynamic stenosis (subtotal or complete occlusion) * supply led ischaemia * unpredictable * dangerous
- e.g. unstable angina, MI
Process of ACS development? (8)
- Vascular damage (e.g. by percutaneous coronary interventions) exposing collagen and VWF
- Platelet adhesion and activation
- Release of ADP (degranulation) and TXA2 via cycloxygenase
- ADP and TXA2 bind to receptors resulting in further aggregation
- Leukocyte recruitment
- Collagen and smooth muscle deposition
- Spontaneous plaque rupture
- Fibrin-rich thrombus
Factors affecting plaque rupture/fissure? (6)
- 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
Does heart have collaterals? What does this mean? What does ST elevation indicate?
- No, end arteries
- If artery blocked, territory starved of oxygen causing MI
- Tells us coronary artery has been blocked and downstream heart muscle is dying
Will patient completely recover from infarct? Symptoms of LVF? (5)
- If survive, dead tissue is replaced with scar tissue which will not contract properly leading to left ventricular failure
Symptoms
- Fatigue
- Breathlessness
- Orthopnoea
- Paroxysmal nocturnal dyspnoea
- Ankle oedema
5 year survival rate of heart failure? Prognosis compared to carcinoma in males/females and lung cancer? (3)
- 25% 5 year survival rate
- HF poorer outcome than large bowel, prostate and bladder cancer in men
- HF poorer outcome than breast, large bowel and ovary cancer in women
- Only lung cancer has worse prognosis than HF
History of MI includes? (4)
- Severe crushing central chest pain
- Radiating to jaw and arms, especially the left
- Similar to angina but more severe, prolonged and not relieved by GTN
- Associated with sweating nausea and often vomiting
Differentiation of attack of angina from acute MI? (5)
- Duration: angina - 10 mins, MI - >30 mins
- Onset: angina - on exertion, MI - at rest
- Severity: angina - usual pain, MI - more severe
- GTN: angina - relief, MI - no relief
- Associated symptoms: angina - none, MI - sweating, nausea, vomiting
Other causes of chest pain other than MI? (4)
- Pneumothroax (sudden onset pain, SOB)
- Bronchopneumonia (pleuritic pain to one side)
- Musculoskeletal pain (worse on movement)
- Heartburn (important mimic of heart pain – often central)
ECG changes in acute STEMI? (4)
- ST elevation (>1mm in 2 adjacent limb leads and >2mm in at least 2 contiguous precordial leads)
- T wave inversion
- Q waves
- New onset bundle branch block
Evolving ECG changes of acute MI? (3)
- ST elevation - first few hours
- Q wave formation and T wave inversion – first day
- “Old MI” – Q waves +/-
inverted T waves
How can you tell anatomical site of myocardial infarction? Examples? (4)
- Inferior - II, III, AVF
- Anterior - V1 - V6
- Anteroseptal - V1-V4
- Anterolateral - I, AvL, V1-V6
Features of left bundle branch block on ECG? What causes left bundle branch block?
- QRS much broader
- Loss of Q waves
- Critical part of heart conducting system has been affected by the infarct
What can also be used in diagnosis of MI other than ECG and history? Examples? (2)
Why are cardiac enzymes and protein markers not as useful as ECG in MI?
- Cardiac enzymes and protein markers
- Enzyme - creatine kinase
- Protein marker - troponin
- Levels may be normal at presentation
- May not have time to wait for results in STEMI
Features of creatine kinase? (2)
Features of troponin? (2)
CK
- peaks in 24 hrs
- also in skeletal muscle and brain (non-specific)
Troponin
- Troponin I and T (not C) highly specific for cardiac muscle damage
- can detect tiny amounts of myocardial necrosis
What does early treatment of STEMI include? Modes of action? (2)
- Antiplatelet drugs like aspirin and clopidogrel
- Aspirin - switches off production of TXA2 by blocking COX1
- Clopidogrel - blocks ADP receptors on platelets so prevents activation
Treatment for patients with acute coronary syndrome? Treatment for patients with cute coronary syndrome with ischaemic ECG changes or elevation of cardiac markers?
- 300 mg aspirin
* 300 mg aspirin and 300 mg clopidogrel (nowadays 180 mg ticagrelor)
Will treatment with aspirin and clopidogrel/ticagrelor alone unblock artery in STEMI? What agents are used for this? Examples? (2)
- Very unlikely
* Thrombolytic agents e.g. streptokinase, t-PA
When does thrombolysis have a greater outcome?
When administered early
