stable angina Flashcards
(54 cards)
what is the biggest cause of stable angina?
atherosclerosis of the coronary arteries - in stable angina it is a stable plaque that causes a reduction in blood flow –> ischaemia (not infarction)
why is angina a symptom of ischaemic heart disease?
atherosclerosis causes a mismatch between the oxygen demand and oxygen supply
what are the different reasons for oxygen and supply mismatch?
- impairment of blood flow due to stenosis
- increased distal resistance to blood flow due to left ventricular hypertrophy
- reduced oxygen carrying capacity of the blood due to anaemia
what does Poiseuille’s law state?
the flow of blood is proportional to the fourth power of the radius
what diameter do the coronary arteries have to reduce by before sb gets symptoms?
75%
what is the name given to the body’s control of flow despite varying BP?
myogenic control
explain the physiology and pathophysiology behind stable angina
normally:
- the resistance of the epicardial vessels is low
- the resistance of the microvasculature is moderate, so blood flow is determined by the resistance (tone) of the microvascular vessels
- under exercise, more flow is needed so the microvascular resistance falls so that flow can increase
in disease:
- the atherosclerosis in the epicardial arteries causes the resistance in the epicardial arteries to increase, so at rest a diseased person will have to dilate their microvascular vessels
- during exercise the microvasculature has to dilate even more and it cannot do this enough so flow cannot meet metabolic demand –> ischaemia
what is prinzmental’s angina caused by?
pain due to coronary artery spasm, leading to reduce blood flow
what is syndrome X (microvascular angina) due to?
the microvessels are narrowed and this leads to an increase in resistance of these vessels
what are the non-modifiable risk factors for stable angina?
Gender
Family history
Personal history
Age
what are the modifiable risk factors for stable angina?
Smoking Diabetes Hypertension Hypercholesterolaemia Sedentary lifestyle ‘Stress’
what factors may precipitate an decreased supply of oxygen?
Anemia Hypoxemia Polycythemia Hypothermia Hypovolaemia Hypervolaemia
what factors increase the demand for oxygen?
Hypertension Tachyarrhythmia Valvular heart disease Hyperthyroidism Hypertrophic cardiomyopathy cold weather heavy meals emotional stress
how does angina present?
chest pain
heavy central tight radiation to arms, jaw, neck
precipitated by exertion
relieved by GTN
what do the letters stand for in socrates?
Site Onset Character Radiation Associated symptoms Time/duration Exacerbating/relieving factors Severity
what are the differential diagnoses of chest pain?
Pericarditis/ myocarditis Pulmonary embolism/ pleurisy Chest infection/ pleurisy Dissection of the aorta Gastro-esophageal (reflux, spasm, ulceration) Musculo-skeletal Psychological
what can be found on medical examination of the pt?
often normal
signs of risk factors
signs of complications (midline sternotomy, legs, pacemaker)
what is Levine’s sign?
when the pt clenches their fist against their chest to describe their angina
what investigations are done for stable angina and what are found?
- ECG - often normal or could be signs of previous MI, eg Q waves, T wave inversion, BBB
- echo - normal or again signs of previous infarcts, done to check LV function
what factors does pre-test probability for CAD take into account?
gender
age
typicality of pain
what should be done with the group who have low pre-test probability?
- investigate other causes
- consider other types of coronary disease
what should be done with the intermediate risk group after pre-test probability?
non-invasive testing for diagnostic purposes
What should be done for pts with a high pre-test probability?
proceed to risk stratification, offer invasive coronary angiography in pts with severe symptoms
what do anatomical tests tell you?
whether there are any anatomical narrowings
