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
What is reperfusion therapy? What are indications for reperfusion therapy? What do contraindications for reperfusion therapy include? (3)
- Includes thrombolysis and PCI
Indications
- Chest pain suggestive of acute MI (more than 30 mins, less than 12 hours)
- ECG changes - acute ST elevation, new bundle branch block (BBB)
- No contraindications
Contraindications
- bleeding ulcer
- haemorrhagic stroke
- surgery
Is thrombolysis only given in hospital?
No, paramedics can administer pre-hospital
Risks of thrombolytic therapy? (3)
- Failure to re-perfuse
- Haemorrhage - Intracranial haemorrhage (2%)
- Hypersensitivity
Probability of an open artery after thrombolysis e.g. SK? What happens to patient with failed thrombolysis or acute reocclusion?
- 50%
* Doubled long term mortality risk
Benefit of PCI over being thrombolysed? What is PCI? Process? (2)
- Decreased risk of CVD events
- PCI - percutaneous coronary intervention i.e. primary angioplasty (GOLD STANDARD)
- Artery opened with wire, ruptured plaque fixed to wall of artery with stent
What is optimal re-perfusion therapy?
- If <2 hrs, PCI (angioplasty) in hospital
* If >2 hrs, thrombolysis in community and taken to PCI clinic
Early treatment of STEMI? (7)
- Analgesia - diamorphine iv
- Anti-emetic - iv (as morphine can induce vomiting)
- Aspirin - 300 mg and clopidogrel 300 mg (now ticagrelor 180 mg)
- GTN - if BP > 90 mmHg
- Oxygen - ONLY if hypoxic (SaO2 <92%)
- Primary angioplasty
- Thrombolysis – if angioplasty not available within 90 minutes
Complications of acute MI? (4)
- Death
- Arrhythmic complications
- Structural complications
- Functional complications
What do arryhmic complications of acute MI include? Treatment?
- Ventricular fibrillation
* Defibrillation (easily treatable)
What do structural complications of acute MI include? (8)
- Cardiac rupture – usually fatal
- Ventricular septal defect
- Mitral valve regurgitation
- Left ventricular aneurysm formation
- Mural thrombus + systemic emboli (can cause stroke)
- Inflammation
- Pericarditis
- Dressler’s syndrome
How is ventricular septal defect treated? Mitral regurgitation?
- Occluding devices inserted to prevent fluid travelling across septum
- Offload the heart with diuretics and then emergency valve replacement surgery
Functional complications of acute MI? (3)
- Acute ventricular failure (left, right, biventricular failure)
- Chronic cardiac failure
- Cardiogenic shock
What is KILLIP classification used for? Explain? (4)
- To predict in-hopsital mortality of heart disease
KILLIP
- I - No signs of heart failure 6%
- II - Crepitations < 50% of lung fields 17%
- III- Crepitations > 50% of lung fields 38%
- IV- Cardiogenic shock 81%
Routine observation of cardiac patients includes? (6)
- Cardiac monitor
- Pulse and blood pressure
- Heart sounds (esp added sounds)
- Murmurs
- Pulmonary crepitations
- Fluid balance (urine output)
What is key trigger for NSTEMI? Why would there be a plaque rupture but no STEMI? Treatment for NSTEMI? (3)
- Atherosclerotic plaque rupture
- Endothelium can produce t-PA – so potential for body to prevent build up of thrombus and occlusion of vessel
- Aspirin, clopigrogrel/ticagrelol, GP IIb, IIIa and PCI
Features of NSTEMI on ECG? STEMI?
- ST depression - sign of cardiac ischaemia
* ST elevation - sign of cardiac injury or infarction
Complications of ACS treatments?
- Minor bleed
- Major bleed
- Allergic reactions
- Acute MI
- Death – bleed out
What is important to remeber about ECG in acute NSTEMI?
ECG MAY BE NORMAL (unlike STEMI, ECG may not tell you there is a problem)
What is used instead of ECG to diagnose NSTEMI? Preferred biomarkers?
- Troponin marker
* TnT or TnI
What does troponin maker tell us in NSTEMI? (2) When is condition labelled as MI?
- Presence of myocardial ischaemia
- Microscopic zones of myocyte necrosis
- Any amount of myocardial ischaemia
What are troponin levels actually measuring? (3)
- Embolisation
- Microvascular circulation
- Myonecrosis
Treatment for all ACS patients (unstable angina, STEMI, NSTEMI)? (3)
- LMWH, Fondaparinux (inhibit coagulation cascade by blocking activation of X)
- B - blockers
- ACEI
What other conditions is TnT elevated in? (8)
- CCF
- Hypertensive crisis
- Renal failure
- Pulmonary embolism
- Sepsis
- Stroke/TIA
- Pericaditis / Myocarditis
- Post arrhythmia
What are classifications of MI? (3)
- 1 - spontaneous MI due to ischaemia from primary coronary event e.g. plaque rupture, dissection
- 2 - MI due to ischaemia from imbalance of O2 supply and demand e.g. coronary embolism, anaemia, arrhythmia, hyper/hypotension
- 3 - sudden unexpected cardiac death with symptoms suggesting ischaemia e.g. ST-segment elevation, new loeft bundle branch block, fresh coronary thrombus
What does type 2 MI occur due to? Is it classed as an MI? What causes ischaemic imbalance?
- Ischaemic imbalance
- Not ACS but MI as troponin is released
- Increased O2 demand due to tachycardia (arrythmia), hyper/hypotension, embolism
Difference beween type 1 and type 2 MI? (3)
- Type 1 - sudden symptoms, major ECG changes, no other obvious cause
- Type 2 - more gradual symptoms, minor ECG changes, secondary causes
What is non-ischaemic myocardial injury with necrosis (NIMI)? MINOCA?
- Not technically type 2 MI but classed as such
* Myocardial infarction with non-obstructive coronary arteries
Conditions associated with NIMI? (3)
- Arrhythmia
- Myocarditis
- Chemotherapy
Benefits of adding clopidogrel/ticagrelor to standard treatment? What is ticagrelor?
- Fewer patients on clopidrogrel/ticagrelor have ischaemia, recurent angina or pulmonary oedema
- ADP antagonist (liek clopidogrel)
What is used to estimate the risk of death from MI in hospital?
GRACE score
What is another drug other than clopidogrel/ticagrelor that blocks platelet aggregation in NSTEMI?
Glycoprotein IIb, IIIa inhibitors e.g. tirofiban
What patients should have angiography (not angioplasty) and revascularisation? (2)
What are 2 revascularisation techniques?
- Patients with NSTEMI at mod/high risk of recurrent cardiovascular events
- Patients with STEMI treated with thrombolytic therapy
- PCI
- Coronary bypass
Types of PCI? (2)
- Percutaneous balloon angioplasty
* Stent placement
Types of stenting? (2)
- Drug-eluting stent
* Bare metal stent
What is troponin-itis? When can you diagnose MI? (4)
- Misdiagnosis of NSTEMI due to raised troponin - other conditions lead to raised troponin
- Only when troponin levels are raised AND one of the following:
- Ischaemia symptoms
- ST changes
- Imaging showing ischaemic changes to heart
- Identification of intracoronary thrombus by angiography
Secondary prevention of MI? (9)
- Smoking cessation
- Control of BP
- Control diabetes
- Control cholesterol (statins)
- Aspirin + clopidogrel
- B-blockers (atenolol/bisoprolol)
- ACEI (ramipril/perinopril)
- Simvastatin/atervastatin
- GTN spray
Cardiac rehabilitation post-MI?
- Cardiac rehabilitation nurses
- Physiotherapy exercise classes
- Smoking cessation specialists
- Pharmacists, nutritionists, clinical psychologists
- Cardiologists
Targets for cholesterol in secondary prevention? BP? (2)
- Cholesterol <4 mmol/l
- BP <140/85 mmHg
- Diabetes, renal disease, target organ damage <130/80 mmHg