Ischaemic heart disease Flashcards
Define ischaemic heart disease
Characterised by decreased blood supply to the heart muscle resulting in chest pain (angina pectoris)
May present as stable angina or acute coronary syndrome
Acute coronary syndrome subdivisions
3
Unstable angina - chest pain at rest due to ischaemia but without cardiac injury
NSTEMI
STEMI - ST elevation w/ transural infarction
Define myocardial infarction
cardiac muscle necrosis resulting from ischaemia
Aetiology of ischaemic heart disease
3
Angina pectoris occurs when myocardial oxygen demand exceeds oxygen supply
Usually due to atherosclerosis
Rare causes: coronary artery spasm (e.g. induced by cocaine), arteritis, emboli
Pathophysiology of atherosclerosis
3
Endothelial injury —> migration of monocytes to sub endothelial space
Monocytes differentiate into macrophages which accumulate LDLs & become foam cells
Foam cells release growth factors that stimulate smooth muscle proliferation, production of collagen & proteoglycans —> formation of atherosclerotic plaque
Risk factors for ischaemic heart disease
6
Male Diabetes mellitus FH Hypertension Hyperlipidaemia Smoking
Epidemiology of ischaemic heart disease
prevalence x2, gender, incidence
COMMON
Prevalence >2%
More common in males
Annual incidence of MI un UK 5/1000
Presenting symptoms of ischaemic heart disease - ACS
9
Acute onset chest pain
Central, heavy, tight, crushing pain
Radiates to arms, neck, jaw or epigastrium
Occurs at rest
More severe & frequent pain than previously occurring stable angina
Associated symptoms: breathlessness sweating N&V SILENT INFARCTS (elderly & diabetics)
Presenting symptoms of ischaemic heart disease - stable angina
Chest pain brought on by exertion & relieved by rest
Signs of ischaemic heart disease on physical examination - ACS
(10)
May be NO CLINICAL SIGNS Pale Sweating Restless Low grade pyrexia Check both radial pulses to rule out aortic dissection Arrhythmias Disturbances of BP New heart murmurs Signs of complications (e.g. acute heart failure, cardiogenic shock)
Signs of ischaemic heart disease on physical examination - stable angina
Check for signs of risk factors
Investigations for ischaemic heart disease
9 groups
Bloods ECG CXR Exercise ECG Radionuclide myocardial perfusion imaging (rMPI) Echocardiogram Pharmacological stress testing Cardiac catheterisation/angiography Coronary calcium scoring
Investigations for ischaemic heart disease - bloods
9
FBC U&Es CRP Glucose Lipid profile Cardiac enzymes (troponin & CK-MB) Amylase (pancreatitis can mimic MI) TFTs AST & LDH (raised 24 & 48 hrs post MI respectively)
Investigations for ischaemic heart disease - ECG
1 unstable angina/NSTEMI + 4 STEMI
Unstable angina or STEMI
May show ST depression or T wave inversion
STEMI Hyperacute T waves ST elevation (> 1mm in limb leads, > 2mm in chest leads) New onset LBBB Later changes: T wave inversion pathological Q waves
ECG leads & sides of the heart
4
Inferior - II, III, aVF
Anterior - V1-5/6
Lateral - I, aVF, V5/6
Posterior - tall R wave & ST depression in V1-3
Investigations for ischaemic heart disease - CXR
Check for signs of heart failure
Investigations for ischaemic heart disease - exercise ECG
3 indications + 3 results
Indications
Patients w/ troponin negative ACS or stable angina w/ high pretest probability of coronary heart disease
Pretest probability based on characteristics:
chest pain, cardiac risk factors, age, gender
Digoxin associated w/ false positive result
(& β-blockers reduce HR so should be stopped before test)
Results
Positive test: > 1mm horizontal or downsloping ST depression measured 80ms after end of QR complex
Failed test: failure to achieve at least 85% of predicted maximal heart rate (220-age) & otherwise negative findings (no chest pain or ECG changes)
Resting ECG abnormalities: e.g. pre excitation syndrome, >1mm ST depression, LBBB or pacemaker ventricular rhythm
Investigations for ischaemic heart disease - radionuclide myocardial perfusion imaging
(3)
Uses technetium-99m sestamibi or tetrofosmin
Can be performed under stress or at rest
Stress testing shows low uptake in ischaemic myocardium
Investigations for ischaemic heart disease - echocardiogram
2
Measured left ventricular ejection fraction
Exercise or dobutamine stress echo may detect regional wall motion abnormalities
Investigations for ischaemic heart disease - pharmacological stress testing
(3)
Used in patients unable to exercise
Pharmacological agents used to induce tachycardia - e.g. dipyridamole, adenosine, dobutamine
Used in conjunction w/ various imaging modalities (e.g. rMPI, echocardiography) to detect ischaemic myocardium
Dipyridamole & adenosine contraindicated in AV block & reactive airway disease
Investigations for ischaemic heart disease - cardiac catheterisation/angiography
Performed if ACS w/ positive troponin or high risk on stress testing
Investigations for ischaemic heart disease - coronary calcium scoring
(2)
Uses specialised CT scan
May useful in outpatients w/ atypical chest pain or in acute chest pain that isn’t clearly due to ischaemia
Management of stable angina
5
Minimise cardiac risk factors
e.g. BP, hyperlipidaemia, diabetes
All patients should receive aspirin 75mg/day unless contraindicated
Immediate symptom relief
e.g. GTN spray
Long term management
β-blockers
Calcium channel blockers
Nitrates
Percutaneous coronary intervention (PCI)
Performed in patients w/ stable angina despite maximal tolerable medical therapy
Coronary artery bypass graft (CABG)
Occurs in more severe cases (e.g. three-vessel disease)
Β blockers contraindicated in…
5
acute heart failure cardiogenic shock bradycardia heart block asthma
Management of unstable angina/NSTEMI
12
Admit to coronary care unit
Oxygen, IV access, monitor vital signs & serial ECG
GTN
Morphine
Metoclopramide (to counteract morphine nausea)
Aspirin (300mg initially, 75mg indefinitely)
Clopidogrel (300mg initially, 75mg for at least 1 yr if troponin positive or high risk)
LMWH (e.g. enoxaparin)
β-blocker (e.g. metoprolol)
Glucose-insulin infusion if blood glucose >11 mmol/L
GIpIIb/IIIa inhibitors may also be considered (e.g. tirofiban) in patients:
undergoing PCI
at risk of further cardiac events
If little improvement, consider urgent angiography with/without revascularisation
MONABASH pneumonic for…
Management of unstable angina/NSTEMI
Morphine Oxygen Nitrates Anticoagulants (aspirin + clopidogrel) β-blockers ACE inhibitors Statins Heparin
Management of STEMI
7 groups
Same as UAP/NSTEMI management except:
Clopidogrel
Primary PCI
Thrombolysis
Secondary prevention
Advice
CABG
Management of STEMI - clopidogrel
4
600mg if patient is going to PCI
300mg if undergoing thrombolysis & <75 yrs
75mg if undergoing thrombolysis & >75 yrs
Maintenance 75mg daily for at least 1 yr
Management of STEMI - primary PCI
3
IV heparin (plus GIpIIb/IIIa inhibitor)
Bivalirudin (antithrombin)
Goal <90 mins if available
Management of STEMI - thrombolysis
3
Uses fibrinolytics such as streptokinase & tissue plasminogen activator (e.g. alteplase)
Only considered within 12 hrs of chest pain & ECG changes & not contraindicated
Rescue PCI may be performed if continued chest pain or ST elevation after thrombolysis
Management of STEMI - secondary prevention
5
Dual antiplatelet therapy (aspirin + clopidogrel) β-blockers ACE inhibitors Statins Control risk factors
Management of STEMI - advice
No driving for 1 month after MI
Management of STEMI - CABG
Consider in patients w/ left main stem or three-vessel disease
Complications of ischaemic heart disease - general
2
Increased risk of MI & other vascular disease (e.g. stroke, PVD)
Cardiac injury from an MI can lead to heart failure & arrhythmias
Complications of ischaemic heart disease - early
8
Death Cardiogenic shock Heart failure Ventricular arrhythmias Heart block Pericarditis Myocardial rupture Thromboembolism
Complications of ischaemic heart disease - late
6
Ventricular wall rupture Valvular regurgitations Ventricular aneurysms Tamponade Dressler’s syndrome Thromboembolism
DARTH VADE pneumonic for…
Complications of ischaemic heart disease
Death Arrhythmias Rupture Tamponade Heart failure Valve disease Aneurysm Dressler’s syndrome Embolism
Prognosis of ischaemic heart disease
2
TIMI score (0-7) can be used for risk stratification TIMI = thrombolysis in myocardial infarction High TIMI score associated w/ high risk of cardiac events within 30 days of MI
Killip classification Class I: no evidence of heart failure Class II mild to moderate heart failure Class III: over pulmonary oedema Class IV: cardiogenic shock
