Cardiac Function and Markers Flashcards
How does ischaemia lead to CVD?
Muscle pain and damage leads to angina and MI
Describe how the atherosclerotic process leads to MI?
Plaque formation
Plaque destabilises
Ruptures with lipid core exposed
Leads to platelet activation/aggregation (White thrombus)
Progression to thrombotic occlusion (red thrombus)
What are the properties of an ideal marker?
High [tissue]
Released quickly and cytoplasmic
Tissue specific
Average half life
What percentage denotes high risk of a cardiac event in the next ten years?
> 20%
What is hsCRP?
Phase protein made by liver or adipose tissue
Assists complement binding and phagocytosis aiding the atherosclerotic process
1-3mg/L = ~ risk
> 3mg/L = high risk
What are the issues with aspartate aminotransferase (AST)?
Not cardiac specific
Slow to rise so no value in late presenting MI
What are the problems with LDH/BDH?
Present in most tissues
No value in late presenting MI
What are the problems with creatinine kinase as a marker?
Present in skeletal muscle as well
Why is CK-MB a good marker?
Relatively heart specific
But not good for late presenting MI! (Rises very high very early)
What is troponin?
Thin filament component in striated muscle
Has 3 subunits
T - tropomyosin binding
I - inhibitory
C - calcium binding
How is troponin used as a bio marker?
Heart specific
High assay sensitivity has led to more people diagnose
Indicates heart failure, disease, inflammation
Problem: can also indicated renal failure
What is heart failure?
Heart damage - over stretching
Weaker heart muscle
LV baggy and large
Fluid is in the wrong places
Why is BNP or nt-BNP a good bio marker?
Released upon cardiac stretching
Opposes vasoconstriction and decreases salt and water retention
Helps rule out or confirm POSSIBILITY of heart failure
Can be done as a point of care test (quick, cheap in GP practice)
What are the two types of MI?
Type I - rupture with thrombus formation
Type II - impaired blood supply to muscle
