Ischaemic heart disease Flashcards
What are the non-modifiable risk factors for IHD?
- age
- sex (males>females)
- family history of CVD
- ethnicity
- genetics e.g. hypercholesterolaemia
- previous history
What are the modifiable risk factors for IHD?
- high blood pressure
- total cholesterol
- smoking
- diabetes
- BMI
- smoking
- diet
- exercise
- stress
- low socioeconomic state
- alcohol
- medications
What is ischaemic heart disease/coronary heart disease?
- heart problem caused by narrowed coronary arteries that supply blood to the heart muscle (demand>supply)
- manifests as myocardial infarction and ischemic cardiomyopathy
- some deaths are sudden due to acute coronary occlusion
What is angina?
- chest pain
- sometimes mistaken for indigestion or heart burn
- aching, burning, fullness, heaviness, numbness, pressure, squeezing
- radiation to arms, back, jaw, neck, shoulder
- occur w/ high or low bp
- sometimes syncope
What can cause obstruction to coronary blood flow?
- atheroma
- thrombosis
- spasm
- embolus
- coronary ostial stenosis
- coronary arteritis
What can cause a general decrease of oxygenated blood flow to myocardium?
- anaemia
- carboxyhaemoglobulinaemia
- hypotension causing decreased coronary perfusion pressure
What is a stable atherosclerotic plaque?
- fibrous cap surrounding lipid-rich necrotic core
- fibrous cap provides effective barrier preventing plaque rupture
- T-reg cells and macrophages produce TGF-beta, which maintains fibrous cap quality by stimulating collagen production in SMCs
How does a plaque become vulnerable?
- due to unresolved inflammation, which causes thinning of the fibrous cap
- thin areas of fibrous cap are prone to rupture, exposing prothrombotic components to platelets and coagulation factors–> thrombus formation
How do patients present with CHD/IHD?
- asymptomatic plaque
- chronic stable angina= stable fixed atherosclerotic plaque (narrowing)
- acute coronary syndromes: unstable angina (plaque disruption and platelet aggregation), non-ST elevation MI (thrombus) , STEMI (thrombus blocking vessel)
What is a coronary embolus?
when a blood clot breaks away and blocks a more distal artery
How does acute coronary occlusion occur?
- in people w/ underlying atherosclerotic disease
- local blood clot/thrombus formation–> grows until occludes vessel (can also become embolus)
- N.B. local muscular spasm of a coronary artery can also add to occlusion
What is the role of collateral vessels in acute hypoxia?
- dilate within seconds of an acute episode
- double by the 2nd or 3rd day and reach normal or almost normal coronary flow within about 1 month
What is the role of collateral vessels in chronic atherosclerotic plaque patients?
slow occlusion occurs, so collaterals can develop at same time while atherosclerosis becomes more and more severe
What causes death after a MI?
- decreased cardiac output
- systolic stretch (dead tissue)
- ventricular fibrillation
- rupture of infarcted area
What risk assessment tools are used for IHD?
- JBS3
- q-risk
What serum markers are used in patients with suspected acute cardiac events?
- troponin (I or T)
- creatine kinase w/ MB isozymes
- lactate dehydrogenase and isozymes
- serum aspartate aminotransferase
What biomarkers can predict death following a MI?
- B-type natriuretic peptide
- CRP
- homocysteine
- renin
- urinary ACR
What are the ECG findings in IHD?
- stable angina: normal ECG but during stress test, might see ST depressions (indicates IHD)
- unstable angina/NSTEMI: ST depressions and T wave inversion
- acute MI/STMI: ST elevation w/ T wave inversion
When is echocardiography used?
to see which area of the heart is damaged following an MI
What is the gold standard investigation for detecting stenosis?
coronary CT angiography
What are HMG-CoA reductase inhibitors?
- they lower LDL levels, raise HDL levels and lower triglyceride levels
- e.g. atorvastatin
What are bile acid sequestrants?
- block enterohepatic circulation of bile acids and inc. decal loss of cholesterol
- e.g. cholestyramine
What are calcium channel blockers?
- relax coronary smooth muscle and produce coronary vasodilation, improving myocardial oxygen delivery
- e.g. amlodipine
What are beta-blockers?
- block symapathetic stimulation of heart
- reducing HR and contractility
- decreasing myocardial oxygen demand–> relieving angina
What are antianginal agents?
- ronalazine
- new
- relieve ischaemia by reducing myocardial cellular sodium and calcium overload
- works on ion channels
- relaxes heart
What is percutaneous coronary intervention?
- angiography and stent placement
- common to treat stable CAD
- improves blood flow by placing stent and compressing plaque
What is coronary artery bypass grafting?
- vessel from another part of body create a graft that allows blood to flow around blocked/narrowed coronary artery
- open heart surgery for people w/ severely narrowed coronary arteries
