Angina Pectoris - BM5 RCR1

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  • Created by: 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)
    • 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
    • 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
      • 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
        • 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
      • Potassium-channel activator e.g.Nicorandil
        • Vasodilation through activation of vascular smooth muscle K+ channels

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