2. IHD - Angina Flashcards
Define angina.
Angina is a type of IHD. It is a symptom of O2 supply/demand mismatch to the heart experienced on exertion.
What is angina pectoris?
Chest pain arising from the heart as a result of myocardial ischaemia
Name 3 types of angina
Classic/stable
Unstable/crescendo
Prinzmetal’s
What is Prinzmetal’s (variant) angina?
Angina that occurs without provocation, usually at rest - due to coronary artery spasm.
What are the differences between stable and unstable angina?
Stable angina is induced by effort + relieved by rest.
Unstable angina occurs at rest.
What is the most common cause of angina?
Narrowing of the coronary arteries due to atherosclerosis, leading to myocardial ischaemia
Give 5 possible causes of angina.
- Narrowed coronary artery = impairment of blood flow e.g. atherosclerosis.
- Increased distal resistance = LV hypertrophy.
- Reduced O2 carrying capacity e.g. anaemia.
- Coronary artery spasm.
- Thrombosis.
Give 5 modifiable risk factors for angina.
- Smoking.
- Diabetes.
- High cholesterol (LDL) / hyperlipidemia
- Obesity/sedentary lifestyle.
- Hypertension.
Give 3 non-modifiable risk factors for angina.
- Increasing age.
- Gender, male bias.
- Family history/genetics.
Give 5 risk factors for angina
Diabetes, smoking, hyperlipidaemia, hypertension, family history, lack of exercise
Briefly describe the pathophysiology of angina that results from atherosclerosis.
On exertion there is increased O2 demand. Coronary blood flow is obstructed by an atherosclerotic plaque -> myocardial ischaemia -> angina.
Briefly describe the pathophysiology of angina that results from anaemia.
On exertion there is increased O2 demand. In someone with anaemia there is reduced O2 transport -> myocardial ischaemia -> angina.
When does myocardial ischaemia occur?
Occurs when there is an imbalance between the heart’s oxygen demand and supply, usually from an increase in demand (eg exercise) accompanied by limitation of supply
What can cause a limitation in oxygen supply?
- Impairment of blood flow by proximal arterial stenosis
- Increased distal resistance E.G. left ventricular hypertrophy
- Reduced oxygen-carrying capacity of blood
E.G. Anaemia
How do blood vessels try and compensate for increased myocardial demand during exercise?
When myocardial demand increases e.g. during exercise, microvascular resistance drops and flow increases!
Why are blood vessels unable to compensate for increased myocardial demand in someone with CV disease?
In CV disease, epicardial resistance is high meaning microvascular resistance has to fall at rest to supply myocardial demand at rest. When this person exercises, the microvascular resistance can’t drop anymore and flow can’t increase to meet metabolic demand = angina!
How can angina be reversed?
Resting - reducing myocardial demand.
How would you describe the chest pain in angina?
Crushing central chest pain. Heavy and tight. The patient will often make a fist shape to describe the pain.
Give 5 symptoms of angina.
- Crushing central chest pain.
- The pain is relieved with rest or using a GTN spray.
- The pain is provoked by physical exertion.
- The pain might radiate to the arms, neck or jaw.
- Breathlessness.
Describe the presentation of angina
Central, crushing, retrosternal chest pain - comes on with exertion, relieved by rest.
May radiate to arms and neck
Give some clinical features, apart from pain, of angina
Dyspnoea, nausea, sweating, faintess
Give 3 symptoms you will NOT /rarely find in angina presentation.
- No fluid retention (unlike heart failure)
- Palpitation (not usually)
- Syncope or pre-syncope (very rare)
List some things that can exacerbate angina
Exercise, cold weather, emotional stress - anger, excitement, heavy meals
Describe the history taking of suspected angina.
- Personal details (demographics, identifiers)
- Presenting complaint
- History of PC + risk factors
- Past medical history
- Drug history, allergies
- Family history
- Social history
- Systematic enquiry
What tool can you use to determine the best investigations and treatment in someone you suspect to have angina?
Pre-test probability of CAD. It takes into account gender, age and typicality of pain.
What investigations might you do in someone you suspect to have angina?
- ECG - usually normal, there are no markers of angina.
- Echocardiography.
- CT angiography - has a high NPV and is good at excluding the disease.
- Exercise tolerance test - induces ischaemia.
- Invasive angiogram - tells you FFR (pressure gradient across stenosis).
What investigation would you carry out on a patient with angina? What would you find?
Exercise ECG test - ST depression, flat/inverted T waves
List the differential diagnoses of central chest pain.
Angina, ACS, pericarditis, myocarditis, aortic dissection, massive PE, musculoskeletal, GORD
A young, healthy, female patient presents to you with what appears to be the signs and symptoms of angina. Would it be good to do CT angiography on this patient?
Yes. CT angiography has a high NPV and so is ideal for excluding CAD in
younger, low risk individuals.
Describe the primary prevention of angina.
- Risk factor modification.
- Low dose aspirin
Name 2 drugs that might be used in someone with angina or in someone at risk of angina to improve prognosis.
- Aspirin.
- Statins
How does aspirin work as a method of secondary prevention in angina?
Inhibits COX2 and formation of thromboxane A2 (TXA2) - a platelet aggregating agent.
So: platelet aggregation is reduced!
Reduces risk of coronary events.
What is the side effect of aspirin to be cautious of?
Caution: Gastric ulcers!
Name an alternative to aspirin in secondary prevention of coronary events.
Clopidogrel
Describe the secondary prevention of angina.
- Risk factor modification.
- Pharmacological therapies for symptom relief and to reduce the risk of CV events.
- Interventional therapies e.g. PCI.
Name 3 symptom-relieving pharmacological therapies that might be used in someone with angina.
- Beta blockers.
- Nitrates e.g. GTN spray.
- Calcium channel blockers.
Describe the action of beta blockers.
Beta blockers are beta 1 specific. They antagonise sympathetic activation and so are negatively chronotropic and inotropic. Myocardial work is reduced and so is myocardial demand = symptom relief.
Describe the mechanism of action of beta blockers in improving symptoms of angina
By acting on Beta-1 receptors in the heart, they reduce the force of contraction and speed of conduction in the heart - relieves myocardial ischaemia by reducing cardiac work and oxygen demand
Give some examples of beta-blockers
Bisoprolol, atenolol, propranolol, metoprolol
Give 3 side effects of beta blockers.
- Bradycardia.
- Tiredness.
- Erectile dysfunction.
- Cold peripheries.
When might beta blockers be contraindicated?
They might be contraindicated in someone with asthma or in someone who is bradycardic.
What is the major contra-indication of beta-blockers?
Why?
Asthma - beta blockers also act on Beta-2 receptors which are found in the smooth muscles of airways - cause bronchoconstriction!
Describe the action of nitrates.
Nitrates e.g. GTN spray are venodilators. Venodilators -> reduced venous return -> reduced pre-load -> reduced myocardial work and myocardial demand.
Describe the mechanism of action of short-acting (GTN) nitrates and long-acting nitrates in acute angina
Nitrates are converted to NO, which increases cGMP and reduces intracellular calcium in vascular smooth muscle cells - vasodilation of venous capacitance vessels reduces preload and LV filling.
Reduced cardiac work and myocardial oxygen demand - relieve angina
Describe the action of Ca2+ channel blockers.
Ca2+ blockers are arterodilators -> reduced BP -> reduced afterload -> reduced myocardial demand.
Give some examples of calcium channel blockers
Diltiazem, amlodipine, nifedipine, verapamil
Describe the mechanism of action of calcium channel blockers in controlling symptoms of stable angina
Decrease calcium entry into vascular and cardiac cells. they reduce myocardial contractility and suppress cardiac conduction - reduce heart rate, contractility and afterload - reduces myocardial oxygen demand - prevents angina.
What are the major side effects of calcium channel blockers?
Postural hypotension/dizziness, headache, ankle oedema - due to systemic vasodilation
Outline the NICE guideline for Chronic stable angina.
- Antiplatelet therapy
- Aspirin
- Clopidogrel if aspirin intolerant
- Lipid-lowering therapy
- Statins (simvastatin, atorvastatin, rosuvastatin, pravastatin)
- Short acting nitrate: GTN spray for acute attack
- First line treatment: Beta blocker OR Calcium channel blocker
- If intolerant: SWITCH
- If not controlled: COMBINE
- If intolerant or uncontrolled, consider monotherapy or combinations with:
- Long acting nitrate
- Ivabradine (inhibits If current)
- Nicorandil (K channel activator)
- Ranolazine (inhibits late inward sodium current)
What is revascularisation?
Revascularisation might be used in someone with angina. It restores the patent coronary artery and increases blood flow.
What interventions may be used in when angina worsens?
Percutaneous coronary intervention (PCI) - balloon used to dilate atheromatous arteries (stents can be placed) - via catheter.
Coronary artery bypass grafting (CABG)
Name 2 types of revascularisation.
- PCI.
- CABG (cabbage)
What is involved in a coronary artery bypass graft (CABG)?
Internal mammary artery used to bypass stenosis in the LAD or RCA.
Give 2 advantages and 1 disadvantage of PCI.
- Less invasive.
- Convenient and acceptable.
- High risk of restenosis.
Give 1 advantage and 2 disadvantages of CABG.
- Good prognosis after surgery.
- Very invasive.
- Long recovery time.
