Vasculature of the Heart

Original Author: Sophie Stanley
Last Updated: March 10, 2018
Revisions: 50
Print this page

The entire body must be supplied with nutrients and oxygen via the circulatory system and the heart is no exception. The coronary circulation refers to the vessels that supply and drain the heart. Coronary arteries are named as such due to the way they encircle the heart, much like a crown.

This article will outline the naming, distribution, and clinical relevance of vessels in the coronary circulation.


Naming

Coronary Arteries

Fig 1.0 - Anterior view of the arterial supply to the heart.

Fig 1.0 – Anterior view of the arterial supply to the heart.

There are two main coronary arteries which branch to supply the entire heart. They are named the left and right coronary arteries, and arise from the left and right aortic sinuses within the aorta.

The aortic sinuses are small openings found within the aorta behind the left and right flaps of the aortic valve. When the heart is relaxed, the back-flow of blood fills these valve pockets, therefore allowing blood to enter the coronary arteries.

The left coronary artery (LCA) initially branches to yield the left anterior descending (LAD), also called the anterior interventricular artery. The LCA also gives off the left marginal artery (LMA) and the left circumflex artery (Cx). In ~20-25% of individuals, the left circumflex artery contributes to the posterior interventricular artery (PIv).

The right coronary artery (RCA) branches to form the right marginal artery (RMA) anteriorly. In 80-85% of individuals, it also branches into the posterior interventricular artery (PIv) posteriorly.

Fig 1.2 - Overview of the branching structure of the coronary arteries.

Fig 1.2 – Overview of the branching structure of the coronary arteries.


Cardiac Veins

Blood travels from the subendocardium into the thebesian veins, which are small tributaries running throughout the myocardium. These in turn drain into larger veins that empty into the coronary sinus. The coronary sinus is the main vein of the heart, located on the posterior surface in the coronary sulcus, which runs between the left atrium and 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 inferior vena cava orifice.

Fig 1.4 - Anterior view of the venous drainage of the heart. Supplied by the great and small cardiac veins

Fig 1.4 – Anterior view of the venous drainage of the heart. Supplied by the great and small cardiac veins

There are five tributaries which drain into the coronary sinus:

  • The great cardiac vein is the main tributary. It 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.
  • The 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.
  • Another vein which drains the right side of the heart is the middle cardiac vein. It is located on the posterior surface of the heart.

The final 2 cardiac veins are also on the posterior surface of the heart:

  • On the left posterior side is the left marginal vein.
  • In the centre is the left posterior ventricular vein which runs along the posterior interventricular sulcus to join the coronary sinus.
Fig 1.5 - Posterior view of the heart, showing the venous drainage.

Fig 1.5 – Posterior view of the heart, showing the venous drainage.


Distribution of the Coronary Arteries

In general, the area of the heart which an artery passes over will be the area that it perfuses. The following describes the anatomical course of the coronary arteries. See Appendix A for a tabular overview of the arterial distribution.

The RCA passes to the right of the pulmonary trunk and runs along the coronary sulcus before branching. The right marginal artery arises from 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 towards 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.

Blood Supply to the Heart - Anterior View

Blood Supply to the Heart - Posterior

Clinical Relevance: Coronary Artery Disease

Coronary artery disease or coronary heart disease (CHD) 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 or blockage of the coronary arteries. This may be due to atherosclerosis, thrombosis, high blood pressure, diabetes or smoking. All these factors lead to a 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 a myocardial infarction. 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 can be used to locate the artery that had been occluded as shown in the table.

DescriptionECG leads with changesArtery occluded
InferiorII, III, aVFRCA
AnteroapicalV3 and V4Distal LAD
AnteroseptalV1 and V2LAD
AnterolateralI, aVL, V5 and V6Circumflex artery
Extensive anteriorI, aVL, V2-V6Proximal LCA
True posteriorTall R in V1RCA

Diagnosis and Treatment of Coronary Artery Disease

Fig 1.6 - A coronary angiogram. Two critical narrowings have been labelled.

Fig 1.6 – A coronary angiogram. Two critical narrowings have been labelled.

A blockage in a coronary artery can be rapidly identified by performing a coronary angiogram. The imaging modality involves the insertion of a catheter into the aorta via the femoral artery. A contrast dye is injected into the coronary arteries and x-ray based imaging is then used to visualise the coronary arteries and any blockage that may be present.

Immediate treatment of a blockage can be performed by way of a coronary angioplasty, which involves the inflation of a balloon within the affected artery. The balloon pushes aside the atherosclerotic plaque and restores the blood flow to the myocardium. The artery may then be supported by the addition of an intravascular stent to maintain its volume.

Appendix A – Tabular Overview of the Vasculature of the Heart

ArteryRegion suppliedVein draining region
Right coronaryRight atrium

SA and AV nodes

Posterior part of interventricular septum (IVS)

Small cardiac vein

Middle cardiac vein

Right marginalRight ventricle

Apex

Small cardiac vein

Middle cardiac vein

Posterior interventricularRight ventricle

Left ventricle

Posterior 1/3 of IVS

Left posterior ventricular vein
Left coronaryLeft atrium

Left ventricle

IVS

AV bundles

Great cardiac vein
Left anterior descendingRight ventricle

Left ventricle

Anterior 2/3 IVS

Great cardiac vein
Left marginalLeft ventricleLeft marginal vein

Great cardiac vein

CircumflexLeft atrium

Left ventricle

Great cardiac vein
Edit This Article
126

Average Rating:

Load 3d model