Stable angina Flashcards
What is angina?
Pain in the chest and/or adjacent areas associated with myocardial ischaemia but without myocardial necrosis
What is the defining symptom/factor of STABLE angina?
Pain occurs almost exclusively on exertion
What is the reason people get angina?
Myocardial ischaemia
Mismatch between myocardial demand for O2 and nutrients and it’s supply of them
Myoc. Ischaemia is characterised by mismatch in supply/demand of O2 & metabolites
What would cause a decrease in supply of O2 & metabolites?
Obstructive coronary atheroma (very common)
Coronary artery spasm (uncommon)
Coronary arteritis/inflammation (very rare)
Anaemia (uncommon)
What pathology would cause an increased myocardial demand for O2?
Left ventricular hypertrophy (LVH) -
Thyrotoxicosis
What would cause Left ventricular hypertrophy?
Hypertrophy caused by need for increased systolic force
- Persistant hypertension
- Aortic stenosis / coarctation
- Hypertrophic cardiomyopathy
^ all of the above increase O2 demand and can lead to M. Ischaemia
What is thyrotoxicosis?
Excess of thyroid hormone in the body
What is the most common cause of angina?
Coronary atheroma
Describe how exertion would cause pain, in someone with stable angina
On activity, heart rate increases ∴ higher myocardial oxygen demand
Obstructed coronary flow leads to myocardial ischaemia and ∴ symptoms of angina
What can be causes of ‘exertion’?
Anything that causes a rise in HR &/or BP
Exercise
Anxiety
Emotional stress
After a large meal
Cold weather exacerbates^
Describe the pain felt in angina
Heavy pain/pressure felt in centre of upper chest
Possible radiation of pain down the inside of the (left) arm, neck and jaw
Roughly how big does an atheromatous plaque need to be before symptomatic stable angina would show?
> 70% obstruction of lumen
If an atheromatous plaque is much larger than 70% obstructive, what is likely to happen?
Spontaneous plaque rupture & local thrombosis
Larger degrees of occlusion/blockage
= Acute coronary syndromes
What is the most useful tool in diagnosis of angina?
History
Site
Character
Radiation
Exacerbating factors
Sometimes, myocardial ischaemia can present with no chest pain but other symptoms
What are these symptoms?
Breathlessness on exertion
Excessive fatigue on exertion
Near syncope on exertion
What group of people are most likely to present with painless angina?
The elderly
Those with diabetes mellitus
(these groups have reduced pain sensation)
How is the severity of angina classed?
Canadian classification of angina severity (CCS)
Basically these are classed based on how much exertion is needed before symptoms show
What are the classes of severity of angina?
CCS
1 - Ordinary physical activity does not cause angina, symptoms only on significant exertion
2 - Slight limitation of ordinary activity, symptoms on walking 2 blocks or > 1 flight of stairs.
3 - Marked limitation, symptoms on walking only 1-2 blocks or 1 flight of stairs.
4 - Symptoms on any activity, getting washed/dressed causes symptoms.
With most CV diseases, angina happens most often in those with high cardiovascular risk
What are risk factors?
Age - elderly
Gender - male
Creed
Family/genetics
Smoking Lifestyle/exercise Diabetes mellitus Hypertension Hyperlipedaemia
What are signs on examination of angina?
Tar stains on fingers
Obesity (centripedal)
Xanthalasma and corneal arcus (hypercholesterolaemia)
Abdominal aortic aneurysm arterial bruits, absent or reduced peripheral pulses.
Diabetic retinopathy, hypertensive retinopathy on fundoscopy.
What are signs of exacerbating or associated conditions for angina?
Pallor of anaemia
Tachycardia, tremor, hyper-reflexia of
hyperthyroidism
Ejection systolic murmur, plateau pulse of aortic stenosis
Pansystolic murmur of mitral regurgitation, and
Signs of heart failure such as basal crackles, elevated JVP, peripheral oedema.
What are the investigations for angina?
Bloods:
- Full B count
- Lipid profile
- Fasting glucose
- Electrolytes
- Liver & thyroid tests
CXR
ECG
Exercise tolerance test
Myocardial perfusion imaging
CT coronary angiogram or Invasive angiography
Why would you use a CXR to investigate angina?
Can show other causes of chest pain and can help show pulmonary oedema
Why would you use an ECG to investigate angina?
May be evidence of prior myocardial infarction i.e. pathological Q-waves.
May be evidence of left ventricular hypertrophy i.e. high voltages, lateral ST-segment depression or “strain pattern”.
However, it is normal in 50% of cases
Why is an exercise test commonly used to test for angina?
Useful tool for diagnosing stable angina in those who are able to take the test
Typical symptoms and ST-segment depression for positive test.
A Negative ETT doesn’t exclude significant coronary atheroma, but, if negative at high workload; overall prognosis is good
What would show on an ECG of someone with angina doing an ETT?
Normal at rest
On exertion (with pain): - ST segment depression (it goes way further down than normal)
Why would you use Myocardial perfusion imaging to investigate angina?
Superior to ETT in detection of CAD, localisation of ischaemia and assessing size of area affected.
However it is expensive and involves radiation
How does myocardial perfusion imaging work?
Either exercise or pharmacological stress: adenosine, dipyridamole or dobutamine
IV trace & imaging:
- Normal myocardium takes up stress
- If not seen on exertion = ischaemia
- If not seen at all = infarction
Invasive angiography is only used for investigations in specific circumstances
What are these?
Early or strongly positive ETT (suggests multi-vessel ds).
Angina refractory to medical therapy.
Diagnosis not clear after non-invasive tests.
Young cardiac patients due to work/life effects.
Occupation or lifestyle with risk e.g. drivers etc
What are the benefits of CT coronary angiograms to investigate angina?
Provide a detailed model of the heart
Problems etc are easily seen
What are the benefits of cardiac catheterisation/coronary angiography?
(invasive angiography)
Definition of coronary anatomy with sites, distribution and nature of atheromatous disease enables decision over what treatment options are possible.
Informs decision over whether medication alone or percutaneous coronary intervention (PCI)- most often angioplasty and stenting or coronary artery bypass graft (CABG) surgery
Describe the coronary angiography is carried out
Almost always done under local anaesthetic
Arterial cannula inserted into femoral or radial artery.
Coronary catheters passed to aortic root and introduced into the ostium of coronary arteries.
Radio-opaque contrast injected down coronary arteries and visualised on X-ray.
Imaging/viewing is done in different planes as atheromas are often eccentric in nature
What are the general measures taken, in the treatment of angina?
Reduce the existing risk factors
Management of illness etc:
- Diabetes Mellitus
- Hypertension
- High cholesterol
Lifestyle factors:
- Smoking, exercise etc
What are the 2 basic aims of medical treatment of angina?
1) Relieve symptoms
2) Reduce progression/stabilise the disease
What drugs are available to use to reduce the progression of myocardial ischaemia?
Statins
ACE inhibitors
Aspirin
Why would you use Statins?
Blood cholesterol >3.5 mmol / L
Reduces LDL-cholesterol deposits in atheroma, reducing the growth of plaques
Also stabilises the atheroma, reducing the chance of plaque rupture and Acute coronary syndrome (ACS)
(reduce progression)
Why would you use ACE inhibitors?
Patients with increased CV risk and atheroma
ACE inhibitors stabilise the endothelium, and also reduce the risk of plaque ruptures and ACS
(reduce progression)
Why would you use Aspirin?
Protects the endothelium
Reduces platelet activation/aggregation
Does not actually affect the plaque itself
(reduce progression)
What dosage of Aspirin is normal to give?
What is the alternative if the patient is intolerant?
75mg
Use Clopidogrel if intolerant (Aspirin often causes GI upset)
What classes of agents can be used to relieve symptoms of angina?
ß-blockers
Ca2+ channel blockers
Ik channel blockers
Nitrates
K+ channel blockers
What classes of agents aim to reduce Heart rate and thus relieve symptoms of angina?
What is the target resting HR?
ß-blockers
Ca2+ channel blockers
Ik channel blockers
<60 bpm
Why are ß-blockers used to relieve symptoms?
Lower heart rate:
Reduced cardiac work & anti-arrhythmic effects
Why are Ca2+ channel blockers used?
Lower heart rate & Vasodilation
Heart rate:
Central acting agents - Diltiazem or Verapimil
Alternative to ß-blockers if C-I
Vasodilation:
Peripheral acting agents - dihydropyridines such as:
Amlodipine or Felodipine
Why are Ik channel blockers used to relieve symptoms?
Lower heart rate:
Reduce Sinus node rate
Ivabridine can be used an alternative to ß-blockers
Why are Nitrates used to relieve symptoms?
Vasodilation
Used as short or prolonged acting tablets, patches or as rapidly acting sublingual GTN spray for immediate use
Why are K+ channel blockers used to relieve symptoms?
Used alongside Nitrates for ‘pre-conditioning’
eg Nicorandil
If medical treatment is ineffective, and symptoms are not controlled, what is the treatment route?
Revascularisation - if prognostically beneficial
- Percutaneous coronary intervention (PCI)
- Coronary artery bypass grafting (CABG) - done most
Describe the process of Percutaneous coronary intervention (PCI)
PCI consists of:
Percutaneous transluminal coronary angioplasty (PTCA)
Stenting (now in ~95% procedures)
Similar beginnings to coronary angiography but cross stenotic lesion with guidewire and squash atheromatous plaque into walls with balloon and stent.
What is given in the PCI procedure, if a stent is implanted, and why?
Aspirin & Clopidogrel given together
These agents protect the endothelium & reduce platelet activation
This allows the endothelium to safely cover the stent, and reduces risk of thrombosis
What is the effect of PCI?
Relieves symptoms
No evidence that it improves prognosis
Patient still needs to take disease modifying modification
What are the risks of PCI?
Small risk of procedural complication: death=0.1%, MI=0.2%, emergency CABG=0.05%
Risk of restenosis: varying from 10-15% with bare metal stents and <10% with drug eluting stents
What are the advantages and disadvanages of Coronary artery bypass grafting (CABG)?
Advantages:
- Good symptom reduction (80% symp free at 5 years)
- May confer prognostic benefit in some groups
Disadvantages:
- More risky surgery (1.3% death rate, 3.9% Q-wave MI)
- Vein graft deteriorates after 10 years
- Patients still need to take disease modifying medication
What patients derive prognostic benefit from the CABG procedure?
- > 70% stenosis of left main stem artery
- Significant proximal three-vessel coronary artery disease
- Two vessel coronary artery disease that includes significant stenosis of proximal left anterior descending coronary artery and who have ejection fraction < 50%.
In basic words, what does the CABG do?
Vein conduit removed from arm or leg (eg saphenous)
It is then used to link the left subclavian artery to the coronary artery
Blood from the subclavian goes to the coronary artery
