Heart - Vasculature Flashcards
What are the different coronary arteries?
1) Left coronary artery
- Left anterior descending artery
- Left marginal artery
- Left circumflex artery - in ~20-25% of individuals, the left circumflex artery contributes the posterior interventricular artery.
2) Right common artery
- Right marginal artery
- Posterior interventricular artery (this artery is formed from the RCA in 80-85% of people).
Cardiac veins?
Subendocardium -> thesbian veins -> larger veins -> coronary sinus
The coronary sinus is located on the posterior surface in the coronary sulcus, which runs between the left atrum and the left ventricle. The sinus drains into the right atrium. Within the right atrium, the opening of the coronary sinus is located between the right atrioventricular orifice and the IVC.
There are 5 tributaries that drain into the coronary sinus:
1) Great cardiac vein - main tributary - originates at the apex of the heart and follows the anterior interventricular groove into the coronary sulcus and around the left side of the heart to join the coronary sinus.
2) Small cardiac vein - is also located on the anterior surface of the heart. This passes around the right side of the heart to join the coronary sinus.
3) Middle cardiac vein - drains the right side of the heart.and is located on the posterior surface of the heart.
4) Left marginal vein - left posterior side.
5) Left posterior ventricular vein - runs along the posterior interventricular sulcus to join the coronary sinus.
DIstribution of the coronary artery?
In general, the area of the heart which an artery passes over will be the area that it perfuses.
RCA passes to the right of the pulmonary trunk and runs along the coronary sulcus before branching. The RMA artery arises form the RCA and moves along the right and inferior border of the heart towards the apex. The RCA continues to the posterior surface of the heart, still running along the coronary sulcus. The posterior interventricular artery then arises from the RCA and follows the posterior interventricular groove towards the apex of the heart.
The LCA passes between the left side of the pulmonary trunk and the left auricle. The LCA divides into the anterior interventricular branch and the circumflex branch. The anterior interventricular branch (LAD) follows the anterior interventricular groove toward the apex of the heart where it continues on the posterior surface to anastomose with the posterior interventricular branch. The circumflex branch follows the coronary sulcus to the left border and onto the posterior surface of the heart. This gives rise to the left marginal branch which follows the left border of the heart.
Clinical relevance - coronary artery disease?
Coronary artery disease or coronary heart disease is a leading cause of death, both in the UK and worldwide. It describes a reduction in blood flow to the myocardium and has several causes and consequences.
CHD can result in reduced blood flow to the heart as a result of narrowing of blockage of the coronary arteries. This may be due to atherosclerosis, thrombosis, high BP, diabetes, and smoking. All these factors lead to reduced flow of blood to the heart through physical obstruction or changes in the vessel wall.
Angina pectoris is one consequence of CHD. Angina pectoris describes the transient pain a person may feel on exercise as a result of lack of oxygen supplied to the heart. This pain is felt across the chest but is quickly resolved upon rest. Exercise is a trigger for angina as the coronary arteries fill during the diastolic period of the cardiac cycle. On exercising, the diastolic period is shortened meaning that there is less time for blood flow to overcome a blockage in one of the coronary vessels in order to supply the heart.
If left untreated, angina can soon progress to more severe consequences, such as an MI. The sudden occlusion of an artery results in infarction and necrosis of the myocardium. This means a section of the heart is unable to beat (which part of the heart depends on which artery has become occluded). The ECG leads on which an MI change appears to be used to locate the artery that had been occluded as shown in the table.
