The Coronary Circulation Flashcards
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 but the endocardium receives blood from the chambers of heart
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
Name the branches of the right coronary artery
SA node branch, Atrial branches which supply the right atrium, the right (acute) marginal branch and usually the posterior interventricular branch.
What two arteries form the anastamosis at the apex
The posterior interventricular branch (posterior descending artery) and 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 does the anterior interventricular branch supply?
The sternocostal surface
What artery does the anterior interventricular branch form anastamosis with?
The right coronary artery at the apex.
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 the right atrium and right ventricle, SA and AV nodes, posterior part of IV septum and small areas of walls of left ventricle and left atrium
What does the left coronary artery and its branches supply?
The walls of the left atrium and left ventricle and most of the IV septum including the AV bundle.
What is coronary dominance?
This is the artery that gives off the posterior interventricular (posterior descending) artery. In 80% of people the RCA is dominant.
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%), and finally the circumflex artery (15-20%)
What part of the conducting system is damaged by the left anterior descending artery and the RCA?
LAD - AV bundles and RCA - SA and AV nodes
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 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, Small cardiac (accompanic right margin branch) and Middle cardiac vein all drain into coronary sinus. The anterior cardiac veins drain independently to 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.
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 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) and finally purkinjie fibres.
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.
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)
