Ischaemic Heart Disease and Hypoxia Flashcards
What ischaemic heart disease?
IHD is the term given to heart problems caused by narrowed heart (coronary) arteries that supply blood to the heart muscle.( Mismatch between demand and supply)
What are other names for IHD?
Coronary heart disease (CHD)/Coronary artery disease (CAD)
What are the signs and symptoms of IHD?
Angina Heart Rhythm problems Nausea Sweating Fatigue SOB Reduced exertional activity Leg swelling Diaphoresis
Describe the chest pain in IHD?
Aching, burning, fullness, heaviness, numbness, pressure, squeezing
Radiation in arms, back, jaw, neck, shoulder
High or low BP
Syncope
What are the rhythm problems in IHD?
Palpitations (irregular heartbeats or skipped beats)
Heart murmurs
Tachycardia (Acute coronary syndrome ACS, Acute myocardial infarction AMI)
Atrial fibrillation
Ventricular tachycardia or ventricular fibrillation
S4gallop: A common early finding of diastolic dysfunction
S3gallop: An indication of reduced left ventricular function and a poor prognostic sign
What is IHD often mistaken for?
Indigestion
Heartburn
What are the Non-modifiable risk factors for IHD?
Age Gender Family history of CVD Ethnicity Genetics Previous history of CVD
What are the modifiable risk factors?
High BP Total cholesterol HDL Smoking Diabetes Diet High BMI Alcohol Physical inactivity Stress Low socioeconomic state Medication
What is the percentage contribution of modifiable risk factors to IHD?
70%
When does IHD occur?
imbalance between the supply of oxygen (and other essential myocardial nutrients) and the myocardial demand for these substances
What are the two causes of IHD?
Coronary blood flow to a region may be reduces due to OBSTRUCTION
A general decrease of oxygenated blood flow to myocardium
What causes obstruction?
Atheroma Thrombosis Spasm Embolus Coronary ostial stenosis Coronary arteritis
What causes general decrease in blood flow?
Anaemia
Carboxyhaemoglobulinaemia
Hypotension causing decreased coronary perfusion pressure
What is atherosclerosis?
Complex inflammatory process
Accumulation of lipids
Macrophages
Smooth muscle cells
In the intimal plaques in the large and medium sized coronary arteries
The process is also called Atherogenesis
What triggers atherosclerosis?
Endothelial dysfunction
Mechanical sheer stresses (HTN)
Biochemical abnormalities (elevated and modified LDL, DM, elevated plasma homocysteine)
Immunological factors (free radicals from smoking)
Inflammation ( infection such as chlamydia, Helicobacter)
Genetic alteration
Summarise stages of atherosclerosis pathophysiology
Fatty streak phase
Plaque progression
Stable plaque
Vulnerable plaque
How does IHD present?
Can be asymptomatic
Chronic stable angina
Acute coronary syndromes
Heart Failure
What are acute coronary syndromes?
Unstable Angina
Non ST elevation MI
ST elevation MI
How do acute coronary occlusions occur?
Thrombus forms
Atherosclerotic plaque breaks through the endothelium
Direct contact with the flowing blood
blood platelets adhere to it
fibrin is deposited
Red blood cells entrapped to form a blood clot
The clot grows until the artery occludes the vessel
Why can you still get ACS in the presence of collaterals?
The collaterals can also get atherosclerosis or the damage become so extensive that even the collaterals can not help
Can cause weakening of the heart and hence heart failure
What is the role of collateral vessels?
After an acute episode
Collaterals that were collapsed before start opening due to hypoxic condition
Can supply normal coronary blood flow
What is myocardial infarction?
After an acute occusion the area of muscle that has either zero flow or so little flow that it cannot sustain cardiac muscle function is said to be infarcted
What is the pathogenesis of MI?
Small amount of collaterals open and blood seep into the infarcted area
Local blood vessels dilate and area becomes overfilled with stagnant blood
Muscle fibres use all the remaining oxygen, hemoglobin becomes totally deoxygenated giving bluish brown hue & blood vessels appear engorged despite lack of blood flow
What are later stages of MI?
Vessels walls permeability increases, fluid leak and local tissue oedematous
Cardiac muscle cells swell and due to no blood supply die within few hours
What are the causes of death - after MI?
Decreased cardiac output-systolic stretch and cardiac shock
Damming of blood in body’s venous system
Ventricle fibrillation— can happen during first 10 minutes or
After 1 hour or so—
Rupture of infarcted area
What happens when there is a small area of ischaemia?
little or no death of muscle. Might become non functional temporarily due to lack of nutrients
What happens when there is a large area of ischaemia?
Some in the centre die rapidly within 1 to 3 hours due to complete loss of blood supply
Immediately around is non functional area failure of contraction and impulse conduction
Surrounding non-functional still contracting but weak due to mild ischemia
What are the risk assessment tools for IHD?
QRisk 2018
What are the NICE guidelines for IHD?
5 year health check for those over 40
CVD risk assessment, an assessment of alcohol consumption, physical activity, cholesterol level, BMI
QRisk
What is involved in a clinical history for IHD?
Symptoms—chest pain type etc, any associated symptoms and signs
Age, sex, Ethnicity, Smoking, Ask about other risk factors, Socioeconomic, family history
What is involved in a clinical examination for IHD?
Heart auscultation, BP, BMI, GPE
What lab tests are done with IHD?
LDL, HDL, Triglycerides, lipoprotein a, C-reactive proteins etc
What serum markers are looked at when acute event is suspected?
Troponins(I or T)
Creatine kinasewith MB isozymes
Lactate dehydrogenase and lactate dehydrogenase isozymes
Serumaspartate aminotransferase
What biomarkers can predict death in IHD?
B-type natriuretic peptide CRP Homocysteine Renin Urinary albumin-to-creatinine ratio
What investigation can diagnose IHD?
ECG
Echocardiography
Coronary Angiography
What doe you see on an ECG in stable angina?
Pretty much normal ECG if you want to see the changes do an exercise stress test
During stress test might see ST depressions indicating IHD
What doe you see on an ECG in unstable angina/NSTEMI?
ST depressions and T wave inversion
What do you see on an ECG in acute MI/STEMI?
ST segment elevation with T wave inversion
Q waves
What does Transthoracic echocardiography help to assess?
left ventricular function
wall-motion abnormalities in the setting of ACS or AMI
mechanical complications of AMI
What is Transoesophageal echocardiography most used for?
assessing possible aortic dissection in the setting of AMI
When is stress echocardiography used?
Stress echocardiography can be used to evaluate hemodynamically significant stenoses in stable patients who are thought to have CAD
How is angiography conducted?
iodinated contrast agent is injected through a catheter placed at the ostium of the coronaries.
The contrast agent is then visualized through radiographic fluoroscopic examination of the heart
What is ultrasonography?
Ultrasonography of the common and internal carotid arteries is a noninvasive measure of arterial wall anatomy that may be performed repeatedly and reliably in asymptomatic individuals.
What are the different medications for IHD?
HMG-CoA reductase inhibitors
Bile Acid Sequestrants
Calcium channel blockers
ACE Inhibitors
Beta-blockers
Antianginal Agents
Platelet aggregate inhibitors
Nitrates
What are revascularisation therapies?
Percutaneous coronary Intervention
CABG
What happens in PCI?
Involves angiography and stent placement:
Common to treat stable CAD
Improves blood flow by placing a stent and compressing the plaque
What happens in CABG?
A vessel from another part of your body to create a graft that allows blood to flow around the blocked or narrowed coronary artery. This type of open-heart surgery is usually used only for people who have several narrowed coronary arteries.
What are the WHO recommendations for prevention?
30 mins of physical activity Avoid tobacco Healthy diet Normal body weight Reduce stress
How does typical angina present?
Precipitated by physical exertion
Constricting discomfort in the front of chest, in the neck shoulders, jaw or arms
Relieved by rest
What is prinzmetal angina?
The pain from variant angina is caused by spasm in the coronary arteries caused by exposure to cold, stress, smoking etc.
What is the most powerful independent risk factor in CVD?
Advancing age
What is diaphoresis?
Sweating
What are presenting features of hyperlipidaemia?
Xanthoma
Obesity
What investigations are done for hyperlipidaemia? `
Fasting triglycerides
(12 hour fast)
Total cholesterol
What are some examples of statins?
Simvastatin
Atorvastatin
What is the measure for obesity?
BMI > 30kg/m^2
What is the pharmacological treatment available for obesity?
Orlistat
What surgical procedure is offered for obesity?
If BMI > 40 or >35 with sig comorbidities:
Bariatric procedures e.g. sleeve gastrectomy, gastric banding, Roux-en-Y bypass
