Lecture 5 Flashcards
Myocardial perfusion in health and disease
What are the three large coronary arteries?
Right coronary artery, left anterior descending artery, left coronary artery
Does the epicardium or the endocardium get less blood?
Then endocardium gets less blood, as the perfusion happens during the heart contraction
Where does an infarction start?
In the endocardium
What is the cardiac flow at rest and how much does that differ with skeletal muscles?
1 ml/min/g, this is about 10 times lower in the skeletal muscles
What is different about the capillary density and oxygen extraction in cardiac vs skeletal muscles?
The cardiac muscles have a higher capillary density and more oxygen extraction than the skeletal muscles
How much higher can the flow get in the heart during exercise?
Can get up to 5 times higher
What is the formula for flow?
(Pa-Pv)/ R arterioles
What does R arterioles include?
Pre-arterioles and arterioles
Which vessels dilate during exercise?
All of them
What are the small arterioles sensitive to?
They are metabolite sensitive
What are the intermediate arterioles sensitive to?
They are pressure sensitive
What are the large arterioles/ small arteries sensitive to?
They are flow sensitive
What is the myogenic response?
Dilation or constriction of the vessels in response to pressure changes
Which factors can influence the vessels?
Neurohumoral (Ach, NE)
Metabolic (PCO2,PO2,H,K,adenosine)
Extravascular (compression)
Endo-/paracrine (ANG II, histamine, brodykinin)
Endothelial (dilator: eNOS, COXI, CYP450, constrictor: ECE)
Which pressures can be compensated with autoregulation?
120-40
What is the coronary flow reserve?
How much the blood flow to the coronary arteries can increase
Is there more flow in the endothelium or in the epothelium?
In the endothelium
Does the epothelium or the endothelium have lower reserves?
The endothelium has lower reserves
What is the consequence of having lower reserves?
There is a lower range for autoregulation
Which factors lead to atherosclerosis?
Genetics, diabetes, hypertension, smoking, diet
What is stenosis?
An obstruction of the blood vessels
What does a lower perfusion pressure lead to?
A higher flow, thus lower reserves to increase the flow during exercise (thus get chest pains when exercise)
What can ischaemia lead to?
To anaerobic metabolism, loss of function or cell damage
Within which time do you have to remove the stenosis?
Within 1h, as the infarction affects 80% of the heart within that time
