Cardiovascular disorders

I./1.2.: Right coronary artery (a. coronaria dextra)

I./1.2.1.: Right coronary artery – in general

The right coronary artery (RCA) passes through the wall of the aortic rootand emerges from the outer aspect of the wall of the right aortic sinus. The mean inner diameter of the right main stem at its origin, measured on arterial casts, is 3.39 mm. At first, the initial segment courses distally, anteriorly and to the right, between the right auricle and the infundibulum of the right ventricle. Descending into the atrioventricular groove (coronary sulcus), it becomes embedded in the subepicardial fatty areolar connective tissue. Upon reaching the right acute margin, the artery curves in the coronary groove and courses between the diaphragmatic surface and the base of the heart to the crux (area of the junction of the walls of the four chambers of the heart i.e. the junction of interatrial, interventricular and coronary grooves).

Photo 3.: A szív jobb kamrája és jobb pitvara a jobb koronáriával - Molnár Attila és Balogh Attila. (1) Atrium dextrum ( auricula dextra ); (2) Crista terminalis; (3) truncus pulmonalis; (4) Arteria coronaria dextra; (5) Arteria interventricularis anterior ( LAD ); (6) Ventriculus dexter; (7) Trabecula septomarginalis

In approximately two thirds of the general Hungarian population, the RCA continues its course from the crux in two directions. A larger caliber artery descends in the posterior atrioventricular sulcus towards the apex of the heart. According to the anatomical nomenclature and the name used by clinicians, this is known as the posterior interventricular artery or posterior descending artery. Usually, the posterior interventricular artery ends roughly halfway between the crux and the apex. In cases of dominant RCA, beyond the posterior descending artery, the RCA continues as a smaller caliber artery coursing further within the atrioventricular groove, to the left from the crux giving off left ventricular branches. This lateral extension of the RCA has been described as the right ventricular postero-lateral branch (RVPL) of the RCA, or right postero-lateral branch (RPL) of RCA.

I./1.2.2.: Segments of the RCA

For the precise description of coronary pathology, clinicians divide the main stem of the RCA into two segments. The portion from the origin of RCA to the right margin of the heart is considered the first or anterior segment, while the second or intermediate segment consists of the portion extending from the right margin to the crux.

Some clinicians postulate three segments. The first or proximal segment extends from the ostium of the RCA to its first main ventricular branch; the second or middle segment includes the part from the first main ventricular branch to the right margin (acute margin) of the heart; and the third or distal segment includes the section from the acute margin to the crux of the heart.

I./1.2.3.: Branches of the RCA

Rami of the right coronary tree will be described in the order of branching from its origin to its distal extension and the supplied myocardial regions will be specified. The number of branches is variable and it is worth mentioning that the ventricular branches tend to take off at right angles.

I./1.2.3.1.: Main stem of the RCA - Branches from the first segment of the RCA

1.: Right conus branch (r. [dexter] coni arteriosi)

In approximately half of the population, more than one ostium opens from the right aortic sinus. Frequently the supplementary ostium gives rise to the conus branch that alternatively arises from the proximal segment of the RCA (“third coronary artery”). Usually, the conus branch terminates near the proximal portion of the anterior interventricular sulcus and it supplies the conal myocardium. It is of clinical importance that in normal and pathologic conditions, the right conus branch may establish an inter-coronary anastomosis with the left conus branch from the left anterior descending from the LCA (Vieussens’ arterial ring). Sometimes, an especially strong right conus branch occurs that provides nutrition for a larger area of the right ventricle.

2.: Right superior descending artery - right superior septal - descending septal artery (a. descendens superior dextra)

This vessel arises from the first 10 mm of the proximal RCA, rarely from the right conal artery. It displays variations in its course and according to its different terminations the supplied regions differ including the atrioventricular node, the vasa vasorum of the aortic root, and it may form the anterior portion of the so called Kugel’s anastomotic artery (arteria anastomotica auricularis magna) between the proximal RCA and the circumflex artery.

3.: Right anterior ventricular branches (rr. anteriores ventriculi dextri)

These branches are inconsistent in incidence and number (one or two); they supply the anterior wall of the right ventricular myocardium along with the right marginal branch and the right conal branch.

4.: Right marginal branch – acute marginal branch (r. marginalis dexter)

Near the right acute margin of the heart, the right marginal branch originates from the anterior segment of the RCA and travels along the margin toward the apex of the heart. When no anterior ventricular branches are present, the right marginal and conal branches supply the sternocostal aspect of the right ventricle.

5.: Atrial branches – Right anterior atrial branches (rr. atriales dextri anteriores)

These are small vessels supplying blood to the anterior surface of the right atrium, originating from the proximal segment of the RCA.

6.: Atrial branches – Right sinuatrial nodal artery (a. nodi sinuatrialis [dextra])

Usually this branch is the largest among the atrial vessels, the mean inner diameter was found to be 1.19 mm on average (0.5 mm - 2.3 mm). The right sinuatrial nodal artery arises in most cases in the proximal 30 mm from the right coronary ostium, and then it usually ascends under the right auricle, behind and to the right from the aorta. It terminates by partially or completely encircling the atrio-caval junction (retrocaval, precaval, pericaval termination) forming the central artery of the sinus node. Along its course, it gives off small branches to the antero-medial wall of the right atrium and to the interatrial septum.

I./1.2.3.2.: Branches from the second segment of the RCA

1.: Right posterior ventricular branches (rr. posteriores ventriculi dextri)

These perpendicularly arising posterior ventricular branches are usually shorter than the anterior ones. They supply the proximal portion of the inferior aspect of the right ventricle and the distal portion is supplied by the twigs from the acute marginal branch and the posterior interventricular branch of the RCA.

2.: Right atrioventricular nodal artery (a. nodi atrioventricularis [dextra])

The right atrioventricular artery originates in the crux region from the most distal part of the second RCA segment or from the continuation of the RCA beyond the crux or from the proximal part of the posterior interventricular artery. In left dominant hearts, the atrioventricular artery is derived from the circumflex artery in the crux region.

3.: Right posterior atrial branch (r. atrialis dexter posterior)

The posterior atrial branches supply the corresponding surfaces of the right atrium and form a rich vascular ring around the terminal portion of the inferior vena cava.

I./1.2.3.3.: In right dominant coronary systems:

1.: Posterior interventricular artery – right posterior descending artery (a. interventricularis posterior)

The inferior (posterior) one third of the interventricular septum is supplied by the short branches of the posterior descending artery travelling in the posterior interventricular sulcus toward the apex. However, in most cases it terminates before reaching the apex. The distal part of the interventricular septum is entirely supplied by the back and upward curving terminal portion of the left anterior descending artery (LAD). The adjacent portion of the right ventricular wall receives branches from the posterior interventricular artery.

2.: Right posterior branches of the left ventricle

To the left from the crux, the artery coursing in, then leaving the left posterior part of the coronary sulcus toward the left margin of the heart gives off some branches to supply the proximal part of the inferior aspect of the left ventricle.

3.: Right ventricular posterolateral branch (r. posterolateralis ventriculi sinistri)

The left ventricular branch of the RCA is known as the posterolateral branch. It represents a continuation of the distal RCA beyond the posterior descending artery. This branch traverses the crux to the left (it may reach the left margin of the heart) and gives off varying number of branches to supply the proximal part of the inferior aspect of the left ventricle.