Chronic coronary syndromes/ stable angina Flashcards
What is angina?
- Angina is a symptom which occurs as a consequence of restricted coronary blood flow and is
almost exclusively secondary to atherosclerosis
What is the physiology of angina?
- O2 supply demand mismatch + limitation of supply:
1. Impairment of blood flow by proximal arterial stenosis
2. Increased distal resistance e.g. left ventricular hypertrophy
3. Reduced oxygen-carrying capacity of blood e.g. anaemia
Describe what occurs in Electro-hydraulic analogy: healthy rest
- In the healthy system, the resistance of the epicardial artery is negligible and so the flow
through the system is determined by the resistance of the microvascular vessels - Total flow is around 3ml/s
Describe what occurs in Electro-hydraulic analogy: healthy exercise
- Under exercise conditions more flow is needed to meet metabolic demand
- The microvascular resistance falls so that flow can increase
- Total flow can increase up to around fivefold (15ml/s)
Describe what occurs in Electro-hydraulic analogy: diseased rest
- Epicardial disease causes the resistance of the epicardial vessel to increase
- To compensate, the microvascular resistance reduces in order to maintain flow at 3ml/s
Describe what occurs in Electro-hydraulic analogy: diseased exercise
- Epicardial resistance is high due to the stenosis
- During exercise the microvascular
resistance falls and increase flow - However, there comes a point where minimising microvascular resistance is maxed out and can fall no more – flow cannot meet metabolic demand
- The myocardium becomes ischaemic and pain is typically experienced
- The only way to reverse this is to rest, thus reducing the demand for flow
What are the non-modifiable risk factors of angina?
- Age
- Gender
- Family history
- Personal history
What are the modifiable risk factors of angina?
- Smoking
- Diabetes
- Hypertension
- Hypercholesterolaemia
- Sedentary lifestyle
- Stress
What are exacerbating factors that decrease the supply for angina?
- Anemia
- Hypoxemia
- Polycythemia
- Hypothermia
- Hypovolaemia
- Hypervolaemia
What are exacerbating factors that increase the demand for angina?
- Hypertension
- Tachyarrhythmia
- Valvular heart disease
- Hyperthyroidism
- Hypertrophic cardiomyopathy
- Cold weather
What are other anginas?
- Prinzmetal’s angina (coronary spasm)
- Microvascular angina (Syndrome X)
- Crescendo angina
- Unstable angina
What is seen in the presentation history for angina?
- Chest pain/discomfort
1. Heavy, central, tight, radiation to arms, jaw, neck
2. Precipitated by exertion
3. Relieved by rest/ GTN spray
What is the scoring system for diagnosing angina?
- All worth one mark each in the scoring system:
3/3 = typical angina
2/3 = atypical angina
≤1/3 = non-anginal pain
What are cardiac symptoms of angina?
- Chest pain (tightness/ discomfort)***
- Breathlessness **
- Fluid retention
- Palpitation
- Syncope or pre-syncope
What is the differential diagnosis for chest pain?
- Myocardial ischemia*
- Pericarditis/ myocarditis
- Pulmonary embolism/ pleurisy
- Chest infection/ pleurisy
- Dissection of the aorta
- Gastro-oesophageal (reflux, spasm, ulceration)
- Musculo-skeletal
- Psychological
What is the presentation in examination for angina?
- Often normal/ near normal
- Signs of risk factors:
o Smoking
o Hypercholesterolaemia
o Diabetes
o Hypertension - Signs of complications e.g. scars (pacemakers etc.)
What are investigations for angina?
- 12 lead ECG
- Echocardiogram
- Anatomical investigations
- Physiological investigations
What does an ECG show for angina?
- Often normal – no direct markers of angina
- Signs of IHD: Q waves, T-wave inversion, BBB
What does an echocardiogram show for angina?
- Normal – no direct markers of angina
- Signs of previous infarcts/ alternative diagnoses
- To check LV function
What are anatomical investigations for angina?
- CT angiography
- High NPV
- Low PPV
- Ideal for excluding CAD in
younger, low risk individuals
- Invasive angiography
What are physiological investigations for angina?
- Exercise stress treadmill
- Stress echo
- Perfusion (stress) MRI
What is the treadmill test?
- Induce ischaemia while walking uphill, incrementally fast
- Look for ST segment depression
- Detects a ‘large stage’ of ischaemia
- Many patients unsuitable
- Can’t walk
- Very unfit
- Young females
- No longer on the UK NICE guidelines
What is primary prevention for angina?
- Reducing the risk of CAD and complications
- Risk factor modification
What is secondary prevention for angina?
- Risk factor modification
- Symptomatic therapy vs prognostic therapy
What is the order of intervention for angina?
- Lifestyle changes
- Risk factor and behaviour modification
- Akin to primary prevention - Pharmacological
- To reduce cardiovascular events
- To reduce symptoms - Interventional (PCI and sometimes surgery)
- To reduce events
- To reduce symptoms
What are the 1st line antianginals?
- Betablockers
- Nitrates
- Calcium channel antagonists
What do betablockers act on for angina?
Beta 1 specific
What are the effects of betablockers on the heart?
- Antagonise sympathetic nervous activation
- (Decreases HR, decreases contractility)
- Therefore reduce work of heart (CO) and O2 demand
What are the contraindications of beta blockers?
- Don’t give to someone with severe asthma
- Cause bronchospasm
What do nitrates act on?
- Primary venodilators
- Dilate systemic veins
- Reduce preload on the heart
- Therefore (Frank-S mechanism) reduce work of heart and O2 demand
What do calcium channel antagonists act on?
- Primary arterodilators
- Dilate systemic arteries
- Reduce afterload on the heart
- Reduce energy required to produce same cardiac output – reduce work of heart and oxygen demand
What’s an antiplatelet agent that can be used to treat angina?
Aspirin
What are other drugs that can be used to treat angina?
Statins
ACE inhibitors
What do statins do?
- Reduce events
- Reduce LDL-cholesterol
- Anti-atherosclerotic but other mechanisms of action proposed
Which treatments would be given at the GP?
- Aspirin
- GTN
- β Blocker
- Statin
Which treatments would be given in hospital?
- CTCA/ functional test of ischaemia
- ACE inhibitor
- Long acting nitrate
- Revascularisation: PCI / CABG: MDT meeting
- Ca++ channel blocker
- Potassium channel opener
- Ivabradine
What is revascularisation?
- To restore patent coronary artery and increase flow reserve
- Either when medication fails or when high risk disease identified
What is PCI?
- Percutaneous coronary intervention (PCI- stenting)
What is CABG?
Coronary artery bypass graft
(CABG) surgery
What are the pros of PCI?
Less invasive
Convenient
Repeatable
Acceptable
What are the cons of PCI?
Risk stent thrombosis
Risk restenosis
Can’t deal with complex disease
Dual antiplatelet therapy
What are the pros of CABG?
Better prognosis
Deals with complex disease
What are the cons of CABG?
Invasive
Risk of stroke, bleeding
Can’t do if frail, comorbid
One time treatment
Length of stay
Time for recovery
What are the complications of angina?
- ACS (acute coronary syndrome) – stable becoming unstable
- CCF – coronary-cameral fistula
- Conduction disease
- Arrhythmia
