Angina Pectoris - BM5 RCR1
- Created by: ex-Lechiayim
- Created on: 24-05-14 20:06
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- Angina Pectoris
- Epidemiology
- Affects 14% of men & 8% of women over 65
- Risk is high in those from a poor socio-economic background
- Defined as chest pain or discomfort as a result of the partial occlusion of one or more coronary arteries.
- Can be classed as stable or unstable
- Stable angina implies that the pain is precipitated by predictable factors e.g. exercise
- Unstable angina implies anginal pain that isn't predictable - can be acute
- Clinical Presentation
- Crushing central chest pain radiating to the jaw and left shoulder/arm
- Exacerbated by exercise
- Risk factors
- Smoking
- Family history of CV disease
- Hypertension
- Diabetes Mellitus
- Hyperlipidaemia
- Obesity
- Male, over 55
- Relieved by a GTN spray when tested in GP surgery
- Investigations
- Resting 12 lead ECG
- Inversion of T wave
- Pathological Q wave
- Evidence of a LBBB
- Echocrdiography to assess damage
- Troponin levels (if suggestion of infarction from ECG)
- Resting 12 lead ECG
- Pathophysiology
- Imbalance between oxygen supply and demand in relation to the heart
- Balance may be fine at rest, but during exercise heart O2 demand increases and becomes greater than the supply
- Partial occlusion of one of the coronary arteries due to atheroma
- Aortic stenosis, HOCM and anaemia can be other causes
- Imbalance between oxygen supply and demand in relation to the heart
- Treatment
- Anti-anginal drugs mainly act by decreasing the workload of the heart at the peripheries, hence reducing O2 demand
- Fast-acting relief: GTN spray
- Given sublingually/via a nasal spray to avoid first pass metabolism (100%)
- Pro-drug, forms NO. NO increases cGMP synthesis which in turn activates protein kinase G. This activates myosin light-chain phosphatase, which dephosphorylates myosin and causes vascular smooth muscle relaxation
- Acts mainly on perpheral veins to reduce preload, and hence reduce O2 demand (reducing myocardial work
- Long-acting nitrate: Isosorbide 5-mononitrate
- Long-acting version of GTN
- Can cause, headache, postural hypotension and reflex tachycardia
- Rapid develpoment of tolerance - avoid by taking in the morning only ('recovery' overnight)
- Beta blockers e.g. atenolol
- Antagonise B1 receptors on myocardium (reducing contractility) and SAN/AVN (reducing HR)
- Main benefit is reducing cardiac work and hence oxygen demand
- Antagonise B1 receptors on myocardium (reducing contractility) and SAN/AVN (reducing HR)
- Calcium Channel Blockers
- Dihydropyridine e.g. amlodipine
- Blocks voltage-gated L-type calcium channels
- Produces peripheral arterial vasodilation
- Reduces afterload --> reduces myocardial workload --> reduces O2 demand
- Produces peripheral arterial vasodilation
- Blocks voltage-gated L-type calcium channels
- Non-dihydropyridine e.g. Verapamil
- Main effect is reducing the contractility of the myocardium
- Dilates peripheral arterioles
- Slows conduction to enhance coronary perfusion during diastole
- Dihydropyridine e.g. amlodipine
- Potassium-channel activator e.g.Nicorandil
- Vasodilation through activation of vascular smooth muscle K+ channels
- Epidemiology
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