Stable Angina Flashcards
How is angina pectoris caused?
Caused by reduced blood flow to the heart causing Ischaemia
What is the most common cause (type) of angina?
Coronary atheroma
- On activity with the increased myocardial oxygen demand obstructed coronary blood flow leads to myocardial ischaemia and then the symptoms of angina.
In what situations does myorcardial oxygen demand increase?
It increases in situations where HR and BP rise for example: exercise, anxiety/emotional stress and after a large meal.
At what stenosis does angina occur?
Occurs when >70% stenosis (>70% of the the artery is blocked by plaque build)
- This stenosis occurs the heart to work a lot harder.
How can the heart muscle wall affect angina?
If the heart muscle wall thickens, it can cause angina.
This is caused by:
- Hypertrophic cardiomyopathy (genetic)
- Pumping against high pressures e.g. Aortic stenosis, hypertension.
What are features of angina pectoris?
1, Constricting/ heavy discomfort to the chest, jaw, neck, shoulders or arms.
- Symptoms brought on by exertion!
- Symptoms relieved within 5 min by rest or GTN.
Symptoms of angina pectoris
- Pressure or squeezing in left arm, chest, shoulders, back.
- Shortness of breath
- Diaphoresis (sweating)
- Symptoms relieved after stress.
What are features making angina less likely?
- Sharp/’stabbing’ pain: pleuritic or pericardial
- Associated with body movements or respiration.
- Very localised: pinpoint site.
- Superficial with/or without tenderness.
- No pattern to pain, particularly if often occurring at rest.
- Begins some time after exercise
- Lasting for hours
What are other symptoms on exertion for stable angina?
- Breathlessness on exertion
- Excessive fatigue on exertion for activity undertaken
- Near syncope on exertion
Features of the Canadian classification of angina severity (CCS)
- Ordinary physical activity does not cause angina, symptoms only on significant exertion.
- Slight limitation of ordinary activity, symptoms on walking 2 blocks or >1 flight of stairs.
- Marked limitation, symptoms on walking only 1-2 blocks or 1 flight of stairs.
- Symptoms on any activity, getting washed/dressed causes symptoms.
What are modifiable risk factors coronary artery disease/angina?
know this!
- Smoking
- Lifestyle: exercise and diet
- Diabetes mellitus (glycaemic control reduced CV risk)
- Hypertension (BP control reduced CV risk)
- Hyperlipidaemia (lowering reduces CV risk)
What are non-modifiable risk factors coronary artery disease/angina?
know this!
- Age
- Gender
- Creed
- Family history
- Genetic factors
Examination features for stable angina?
- Tar stains on fingers
- Obesity (centripedal)
- Xanthalasma and corneal arcus (hypercholesterolaemia)
- Hypertension
- Abdominal aortic aneurysm arterial bruits, absent or reduced peripheral pulses.
- Diabetic retinopathy, hypertensive retinopathy on fundoscopy.
Signs of exacerbating or associated conditions for stable 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 methods would you use to investigate stable angina?
- Bloods
- Chest X-ray
- Electrocardiogram
- Exercise tolerance test/ETT
- Myocardial perfusion imaging
- Computed tomography (CT) coronary angiography
- Invasive angiography
- Cardiac catherisation/coronary angiography
What would an X-ray be useful to show?
Often helps show other causes of chest pain and can help show pulmonary oedema
Features of electrocardiogram in stable angina?
- Normal in over 50% of cases
- 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”.
Features of exercise tolerance test/ETT
- Often can confirm diagnosis of angina.
- Relies on ability to walk for long enough to produce sufficient CV stress.
- Typical symptoms and ST-segment depression for positive test.
- -ve ETT doesn’t exclude significant coronary atheroma but if negative at high workload overall prognosis is good.
Features of myocardial perfusion imaging in stable angina
- Superior to ETT in detection of CAD, localisation of ischaemia and assessing size of area affected.
- Expensive, involves radioactivity; depending on availability used where ETT not possible/equivocal.
- Either exercise or pharmacological stress: adenosine, dipyridamole or dobutamine.
When would invasive angiography be used?
If:
- 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.
Features of cardiac catherisation/ coronary angiography
- 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.
What are the different treatment strategies for stable angina?
- General measures: adress risk factors.
- Medical treatment
- Revascularisation (if treatment not controlled)
Medical treatments for influencing disease progression of stable angina
- Statins: consider if total cholesterol >3.5mmol
- ACE inhibitors: if increased Cv risk and atheroma
- Aspirin, 75mg or clopidogrel if intolerant of aspirin
What do statins do?
They reduce LDL-cholsterol deposition in atheroma and also stabilise atheroma reducing plaque rupture and ACS.
What do ACE inhibitors do?
Stabilise endothelium and also reduce plaque rupture
What does aspirin do in stable angina?
May or may not affect plaque but does protect endothelium and reduces platelet activation/aggregation.
Medical treatments for relief of symptoms
- Beta blockers : achieve resting hr <60bpm.
- Ca2+ channel blockers: achieve resting hr< 60 bpm
- Ik channel blockers: achieve resting hr <60bpm
- Nitrates: produce vasidilation
- K+ channel blockers:: nicorandil
What do beta blockers do?
Reduced myocardial work and have anti-arrythmic effects
What do Ca2+ channel blockers do?
Central acting e.g. diltiazem/verapamil if B-blockers C-I
What do Ik channel blockers do?
Ivabridine is a new medication which reduces sinus node rate
What do nitrates do?
Used as short or prolonged acting tablets, patches or as rapidly acting sublingual GTN spray for immediate use.
- Produce vasodilation
What do K+ channel blockers do?
Nitrate molecule and K+ channel helpful in ‘pre-conditioning’
Examples of percutaneous coronary intervention (PCI)
Percutaneous transluminal coronary angioplasty (PTCA) and stenting!!
- Similar beginnings to coronary angiography but cross stenotic lesion with guidewire and squash atheromatous plaque into walls with balloon and stent.
What are risks with percutaneous coronary intervention?
PCI is effective for symptoms, but
- No evidence it improves prognosis in stable disease.
- Small risk of procedural complication: death = 0.1%, MI = 0.2%, emergency CABG = 0.05%
- Risk of restenosis
Features of coronary artery bypass surgery (CABG)
- In diffuse multi-vessel CABG often best option for stable angina
- ‘Up front’ risks are much greater than PCI, death 1.3%, Q-wave MI = 3.9% - these increase in presence of co-morbidity.
- But good lasting benefit, 80% symptom free 5 years later.
Which patients derive prognostic benefit from CABG (coronary artery bypass surgery)?
- With >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%.
