The Coronary Circulation Flashcards
GO OVER WITH NOTES
GO OVER WITH NOTES
What is the blood supply of the heart?
- Right and left coronary arteries (RCA) and (LCA)
- these are the only branches of the ascending aorta
- the endocardium receives blood from the chambers of heart
describe cardiac muscle?
- striated but voluntary
- bibles branch and join with each other with intercalated discs
- works as a single functional organ or syncytium
- synchronised contraction
- does not tetanize.
When do the coronary arteries fill up?
They fill up when the aortic sinuses fill up in diastole.
In systole the aortic valve cusps close the opening of the arteries
describe the the blood supply to the heart?
- supplied by coronary arteries and their branches
where do the coronary arteries energy from?
aortic sinuses
- right coronary
- left coronary
with an anastomoses between them.
where does the endocardium get blood from?
it receives oxygen and nutrients directly from the chamber of the heart.
Name the branches of the right coronary artery
- SA node branch
- AV nodal brunch
- the right (acute) marginal branch
- posterior interventricular branch.
What two arteries form the anastamosis at the apex
- The posterior interventricular branch (posterior descending artery)
- the left coronary artery.
What are the terminal branches of the left coronary artery?
Circumflex branches and anterior interventricular artery (left anterior descending artery LAD).
what are the 4 branches of the right coronary artery?
- SA nodal branch
- Right marginal branch
- Posterior inter ventricular branch
- AV nodal branch
What does the anterior interventricular branch supply?
The sternocostal surface
where does the coronary artery start?
right aortic sinus
Name the branch of the circumflex artery and what artery it forms an anastamosis with.
Left (obtuse) marginal branch. Anastamosis with RCA
What does the right coronary artery and its branches supply?
- walls of right atrium and right ventricle
- SA node and AV node
- posterior part of the inter ventricular septum
- small areas of the walls of left atrium and left ventricle
What does the left coronary artery and its branches supply?
- walls of the left atrium and left ventricle
- most of the inter ventricular septum, including the distal parts of the AV node.
where does the left coronary artery arise from?
- the left aortic sinus between the left auricle and the pulmonary trunk.
- enters into the coronary sulcus
what does the left coronary artery divide into?
- circumflex
- anterior inter ventricular branches
What is coronary dominance?
This is the artery that gives off the posterior interventricular (posterior descending) artery determines the coronary dominance. In 80% of people the RCA is dominant.
left coronary artery branches?
- anterior inter ventricular
- circumflex artery
- left marginal branch
What is coronary co-domincance?
Where both RCA and LCA supply the posterior interventricular artery.
What is the order of frequency of occlusion of arteries that cause MIs
- Left anterior descending artery(40-50%)
- right coronary artery (30-40%),
- the circumflex artery (15-20%)
what may be damaged in the conducting system by a coronary occlusion?
- LAD septal branches (supplies the AV branches)
-RCA supplies both the SA and AV node. - heart block (bradycardia)
What can you do if the artery becomes narrowed or blocked?
Coronary Artery Bypass Grafting (CABG) or Percutaneous Transluminal Coronary Angioplasty
What is a CABG?
This is where you can use another artery (often the internal thoracic artery) to bypass the portion of occluded vessel
what does a CABG do?
- vessels are grafted to bypass blockages
- autograft from internal thoracic, great saphenous
What is Percutaneous transluminal coronary angioplasty?
A catherter is passed through the femoral artery till it reaches the blocked artery, it is then opened by a ballon. A stent may be left and teh stent may be drug eluting.
Name the four coronary veins and where they drain too
- great cardiac vein (anterior interventricular) vein joins the coronary sinus
- small cardiac vein, accompanies the right marginal branch
- middle cardiac (posterior intervetricular) vein drains into the coronary sinus
- anterior cardiac veins drain independently into the RA
Where is the position of the coronary sinus?
It lies between the left atrium and the left ventricle and is surrounded by the muscle fibres of the left atrium.
Name the 2 networks the cardiac muscle forms and what separates them
The atrial and ventricular networks which are separated by the fibrous skeleton.
describe the venous drainage percentage of the coronary sinus?
drains 60% of the venous blood of the heart into the RA
- 40% is drained by the smallest cardiac veins and anterior cardiac veins.
What is the role of the ANS
Shortens or prolings the duration of a cardiac cycle, it however, does not start the heart as it acts independently.
what are the 4 cardiac veins and where do they join??
- great cardiac vein joins the coronary sinus
- small cardiac vein accompanies the right marginal branch
- middle cardiac vein drains into coronary sinus
- anterior cardiac veins drain independently into the RA
What are the compounents of the cardiac conduction system?
- Sino-atrial node,
- Atrioventricular node
- Atrioventricular bundle (Bundle of His) which splits into a left bundle branch and a right bundle branch)
- purkinjie fibres.
what is the difference in position between the SA and AV node?
SA node= anterior to the opening of the SVC, upper end of the crust terminals
AV node= posters-inferior part of the IA septum, close to the opening of the coronary sinus.
Where is the location of the SA node
Anterior to the opening of the SVC at the upper end of crista terminalis.
Where is the rough location of the AV node
At the posto-inferior part of the IA septum close to opening of coronary sinus.
Where is the rough location of the AV bundle?
It runs along the membranous part of the IV septum.
Where is the rough location of the AV bundle branches?
Along the IV septum with the right bundle branch in the septomarginal trabecula. Both bundles split into purkinjie fibres
Describe the nerve supply of the heart
-Supplied by cardioaccelartory and cardioinhibitory centres found in the medulla and the cardiac plexus.
- it supplies the conduction system, coronary blood vessels and myocardium.
What is the effect of the presynaptic sympathetic fibres? and what spinal nerves do they travel in?
They travel in T1-5 spinal nerves and they increase the heart beat, force of contraction and dilate the coronary arteries.
What is the parasympathetic effect and what nerves do they travel in?
Travel in vagus nerve (10th cranial nerve) and it decreases the heart beat and constricts coronary arteries
Where is the referred pain caused by ischaemia and damage to cardiac muscle felt?
Areas of the skin supplied by T1-5 (anterior chest and medial aspect of left arm)
obstruction of the right coronary artery can lead to what?
- anterior infarct
- mild cases will cause ischaemia.
1- obstruction of the left anterior descending causes what?
2- obstruction of the circumflex artery causes what?
3- what kind of infarct causes loss of Left ventricle function and ventricular fibrillation
1 - an anterior or lateral infarct
2- posterior infarct
3- septal infarcts
where do the cells lie that can generate electrical impulses without external stimuli? (group of specialised cells)
they lie immediately below the endocardium
what causes the heart to contract
cardiac muscle cells distribute electrical impulses through the myocardium
what part of the ns shortens or prolongs the duration of the cardiac cycle?
autonomic ns
what are the components of the conduction system?
- SA node
- AV node
- atrioventricular bundle (bundle of HIS) = there is a left and right bundle branch
- Purkinje fibres
describe bundle of HIS?
- runs along the membranous part of the IV septum
- only conductive route through the fibrous skeleton
describe the right bundle of his branch?
- depends on the right side of the membranous part of the IV septum
- enters the septomarginal trabecular to reach the base of the anterior papillary muscle
- splits into Purkinje fibres which spread out into the ventricular walls
describe the left bundle of His branch?
- depends on the left side of the membranous part of the IV septum
- splits into purkinje fibre