Cardiovascular disease Flashcards
Outline the stages in the process of atheroma formation
1) LDL cholesterol attaches to damaged endothelium
2) Monocytes (WBC) engulfs lipoproteins and develop into foam cells - white cells engulf more and more lipoproteins forming a fatty plaque
3) Foam cells die and release lipid causing smooth muscle cells to divide and begin to produce a matrix of protein and collagen enlarging the size of the plaque
4) Fibrous plaque forms helping contain atherosclerotic plaque
What are the 5 typical ways in which the endothelium can become damaged
- Shear stress - Force exerted by blood flow
- Nicotine
- Elevated blood glucose
- Oxidized LDL cholesterol
- Chronic inflammatory conditions (rheumatoid arthritis)
What are the signs and symtoms of angina?
- Tightness in the chest
- Pain/Heavy feeling in left arm but can be right
- Pain in abdomen/back/throat
- Breathlessness on exertion which may occur independently of other symptoms
- Fatigue
What are the 4 common triggers to angina and why?
- Exercise: Increase HR, Increase in BP (afterload)
- Emotional stress: Increase HR, Increase in BP
- Extremely cold environment: Vasoconstriction of peripheral system (afterload), Vasoconstriction of coronary arteries themselves
- Eating a meal: Increase in HR/Stroke volume (Cardiac output) of about 1 litre per minute
What are the characteristics of stable angina?
It is predictable in terms of:
- Severity
- How it is relieved e.g resting with or without GTN
- Onset - Is it brought on by similar situations
It is reproducible - brought on at similar workloads
How is a patient’s coronary artery disease risk calculated?
Rapid access chest pain clinic (RAPC)
- Nature of any chest discomfort
- What triggers the attack
- How long the pain lasts
- How it is relieved
- Patients risk factors for coronary heart disease
What information does an ECG provide?
- Rhythm (regular/irregular)
- Heart rate
- Whether the electrical activity of the atria is normal
- Presence of teamwork between atria and ventricles
- Whether electrical activity of ventricles is normal
- Adequacy of blood flow to the heart muscle - presence of ischemia seen as ST depression
- Diagnose an acute infarction (ST Elevation MI) or previous infarcts
- The site of infarction
- Arrhythmias
What does a Computerised tomography scan involve and who is it commonly used for?
- Patients with an estimated CAD risk of 10-29% (low)
CT scan: - Special dye is injected into a vein
- X-ray machine rotates around the body
- Different types of tissue show up with different colors/Pictures showing images of the area scanned
What does a myocardial perfusion scan involve and who is it commonly used for?
- Patients with an estimated risk of having CAD is 30-60%
MPS: - Patient will exercise to elevate heart rate
- Radio isotope will injected and the patient placed in a scanner
- Ischaemic/Necrotic cells will not take up radio isotope
- Test is repeated with the patient at rest, scans are compared to determine whether ischemia is reversible (only during exercise)
When is myocardial perfusion scanning used?
- To diagnose CHD
- To determine whether an individual would benefit from a revascularization procedure
- Alternative to ECG ETT in patients that can only manage a minimum amount of exercise
- Can be used in those who cannot perform exercise using drugs that mimic effect
Who is a coronary angiography used for and what does it involve?
Patients with a 61-90% risk of CHD (high)
- Small tube is passed into femoral or brachial artery into the ascending aorta where openings to coronary arteries are located
- Radio-opaque dye is injected directly into coronary arteries
- Passage of the radio-opaque medium through coronary arteres during the cardiac cycle is visible on X-Ray
What are the main uses for coronary angiography?
- High likelihood CHD
- Reversible ischaemia proven on myocardial perfusion scan
- Pre-requisite for percustanous coronary intervention or coronary artery bypass graft surgery
- Angina after myocardial infarction (residual)
- Angina diagnosis is uncertain
- Prior to valve replacement surgery to determine whether patient also has CHD
What information does a coronary angiography provide and what treatment options might typically be used?
- Site and severity of stenoses (blockages)
- Percutaneous coronary intervention
- Coronary artery bypass graft
- Medical management: Aspirin, nitrates, beta blockers, statins
What is the recommended procedure for the use of GTN (Glyceryl trinitrate)
- Stop activity sit down and rest
- If no immediate relief from chest pain, taken GTN spray/tablets
- Take a second dose after 5 mins
- Dial 999 if no relief after 2nd dose
- If symptoms relieved, rest for 5 mins then rewarm before resuming exercise
What durgs are typically used to prevent heart attack/stroke?
Aspirin - Antiplatelet drug reduced risk of blood clots forming
Statins - Lower cholesterol levels and slow down further atheroma formation
What 4 drugs are typically used to reduce symptoms of angina and how do they work?
1) Beta blockers:
- Lowers heart rate, lengthening diastole so coronary perfusion is improve
- Reduced workload by reducing HR, BP and contractility of heart
2) Calcium channel blockers:
- Increase blood supply by vasodilating coronary arteries and inhibiting smooth-muscle contraction and resulting coronary artery spasm
3) Potassium channel activators:
- Increase perfusion by dilating coronary arteries
- Dilate veins to reduce preload and dilate arteries reducing afterload
4) Ivabradine
- Increases blood supply to the heart by reducing HR therefore lengthening diastole and increasing coronary perfusion
Outline the revascularisation treatments for angina
Percutaneous coronary interventions - Restore blood flow by widerning lumen of narrowed artery with a stent
Coronary artery bypass graft - Bypasses blocked artery by taking artery/vein somewhere else in the body
How does acute coronary syndrome occur and what are the different types?
Fibrous plaque ruptures with sticky platelets adhering to the ruptured area forming a clot or thrombus - Unstable angina - Myocardial infarction NSTEMI (no ST Elevation on ECG) STEMI (ST Elevation on ECG)
Outline the guidelines for diagnosing acute coronary syndrome
- Resting ECG
- Blood tests
Troponins should be tested 6-12 hours after initial assessment to indicate cardiac injury - Unstable angina will also test for history
How does unstable angina occur and how does it present itself?
- Occurs when platelets stick but dissolve on their own
- New-onset angina - no pattern is yet established
- Angina at rest
- Increased, frequency and severity
- Occurs at lower levels than normal