Pathophysiology of ischaemia and infraction (part 1) Flashcards
Define ischaemia?
relative lack of blood supply to tissue/organ leading to inadequate O2 supply to meet needs of tissue/organ: hypoxia
What is hypoxic?
a) low inspired O2 level
b) normal inspired O2 but low PaO2
What is anaemic?
normal inspired O2 but blood abnormal
not enough haemoglobin to carry oxygen
What are the 4 types of hypoxia?
hypoxic
anaemic
stagnant
cytotoxic
What is stagnant hypoxia?
normal inspired O2 but abnormal delivery
What are 2 types of stagnant hypoxia?
local e.g. occlusion of vessel
systemic e.g. shock
What is cytotoxic hypoxia?
normal inspired O2 but abnormal at tissue level
tissue cannot use oxygen that is being delivered to it
What factors effect oxygen supply?
inspired O2
pulmonary function
blood constituents
blood flow
integrity of vasculature
tissue mechanisms
What are 2 factors affecting oxygen demand?
- tissue itself - different tissues have different requirements
- activity of tissue above baseline value
What are examples of supply issues in ischaemic HD?
coronary artery atheroma
cardiac failure (flow)
pulmonary function - other disease or pulmonary oedema (LVF)
Anaemia
previous MI
What does it mean that the heart has a high intrinsic demand?
the control of the hearts output/ contraction force
increase cardiac output
What is atheroma/ atherosclerosis?
localized accumulation of lipid and fibrous tissue in intima of arteries
What is the clinical correlation of established atheroma in a cornionary artery?
stable angina
What is the clinical correlation of complicated atheroma in coronary artery?
unstable angina
What is angina?
when the coronary arteries receive not a sufficient blood supply
What are the clinical manifestations of stable angina?
pain on exertion but not at rest