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Angina Pectoris

Definition

  • Chest pain on exertion caused by a lack of blood flow/oxygen to the myocardium

 

Risk Factors

  • Hypertension
  • Diabetes
  • Family history
  • Hypercholesterolaemia
  • Smoking
  • Obesity
  • LV hypertrophy
  • Metabolic syndrome
  • Precipitating factors that increase O2 demand/reduce O2 availability:
    • Anaemia
    • Hyperthyroidism
    • Catecholamines
    • Stress

 

Differential diagnoses

  • Acute coronary syndrome
  • Aortic dissection
  • Acute pericarditis
  • PE
  • Anaemia
  • Biliary colic
  • Cholecystitis
  • Reflux
  • Peptic ulcer
  • Gastritis

 

Epidemiology

  • About 2 million people with Angina in UK
  • 96,000 new cases per year
  • Affects about 14% of men, 8% of women
  • More common with increasing age
  • More common in black people than non-black people
  • 18% coronary attacks preceded by angina

 

Aetiology

  • Insufficient oxygen supply to myocardium, can be a number of causes
  • Increased resistance in coronary vessels, eg from atherosclerosis
  • Increased extravascular forces such as hypertension, LV hypertrophy, aortic stenosis, raised LV diastolic pressure
  • Reduced O2 carrying capacity, eg anaemia, CO poisoning, haemoglobinopathies
  • Congenital abnormalities of the heart or major vessels

 

Clinical features

  • Retrosternal chest pain
    • Dull/pressing/squeezing/burning rather than frank pain
    • NOT sharp
    • Radiation to arms, shoulders and neck
  • May be primarily located in epigastrium, back, shoulders, neck or jaw (but most commonly retrosternal)
  • Generally precipitated by exertion, also by cold, eating or stress
  • Lasts for 1-5 minutes
  • Relieved by rest and NO/GTN
  • Pain intensity doesn’t change with cough, repositioning or breathing
  • Number of classification/staging scales available, based on disability and escalation of pain

 

Pathophysiology

  • Myocardial ischemia causes a change from aerobic to anaerobic respiration
  • During anaerobic respiration, ATP degrades to adenosine, which causes arteriolar dilation and pain
  • Myocardial function is impaired during anaerobic respiration, which reduces the heart’s contraction and conduction abilities
  • Increased metabolic demand on the heart lowers the threshold at which anaerobic respiration is used
    • Raised heart rate and contractility increase metabolic demand
    • Raised afterload and preload increase LV wall tension, which increases metabolic demand
  • Atherosclerosis is main cause of coronary vessel stenosis, which leads to myocardial ischemia

 

Investigations

  • NO trial generally sufficient
  • CXR not normally necessary – usually normal, although can show other cardiac pathology, including calcification of coronary vessels
  • ECG – 50% have normal ECG at rest, of these, 50% will have normal ECG during an attack
    • Most common finding is 1mm or more ST depression
    • Can pick up other (related) cardiac problems including prior MI, conduction block, arrhythmias
    • Exercise ECG useful for those who have normal resting ECG
  • Exercise stress test (to elicit symptoms), can be combined with exercise echocardiogram
  • CT scanning of coronary arteries, assess for calcification
  • Myocardial perfusion scintigraphy
    • Nuclear imaging to assess for hypoperfusion
  • Coronary angiography is definitive test for coronary vascular disease

 

Management

  • Most management options focus on reducing O2 demand rather than increasing O2 supply
  • GTN spray is first line treatment – pain abortive
    • Vasodilation mainly of periphery: decreases afterload and preload à decreased O2 demand
    • Can develop tolerance, and headaches
    • Oral NO options available – isosobide mono/dinitrate
  • Cardioselective beta blockers eg bisoprolol
    • Reduce heart rate and contractility à decreased O2 demand
    • Also increase diastolic filling tie à increased O2 supply
  • Calcium channel blockers
    • Rate limiting/non-dihydropyridines: reduce HR (reduced O2 demand and increased O2 supply), reduce contractility (reduce O2 demand) and vasodilation (reduce preload + afterload à reduced O2 demand), eg verapamil, diltiazem
    • Non-rate limiting/dihydropyridines: vasodilation of arteriolar smooth muscle (reduces afterload à reduced O2 demand), eg amlodipine, nifedipine
  • Manage and modify cardiac risk factors, eg smoking, weight, diabetes, hypertension, hypercholesterolaemia
  • Gentle exercise
  • Healthy diet

 

Prognosis

  • Increased risk of coronary events, which have high mortality
  • LV function is best predictor of long-term survival
  • Angina in itself is not life threatening

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