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