THIRD CORONARY ARTERY

The human hart is in most cases vascularized by two coronary arteries, the right and the left one. Supernumerary or added coronary arteries are also present sometimes. The aim of this paper is to ascertain presence of supernumerary coronary arteries that arise directly from aorta, their frequency, flow, way of branching, and possibly their anastomoses with other coronary arteries. Out of 25 hearts, examined by dissection, 8 of them (32%) had conal artery. According to our opinion, the most suitable term for this artery, in order to differ it clearly from the conal branch of the right coronary artery, is third coronary artery. One heart (4%) had four coronary arteries. Both supernumerary coronary arteries arose from the right aortic sinus. The third coronary artery represents a significant way of collateral coronary circulation, as it frequently anastomoses with anterior interventricular branch.


Introduction
Th e human hart is in most cases vascularised by two coronary arteries, the right and the left one (a.coronaria dextra et a. coronaria sinistra).Supernumerary or added coronary arteries are also present sometimes (,).Supernumerary coronary artery which arises independently from the right aortic sinus (sinus Valsvae) and passes through subepicardial adipose tissue of pulmonary conus and anterior side of the right ventricule, is called third coronary artery, preinfundibular artery or gentle Vieussens' artery (,,).Edwards () and Miyazaki () state that the third coronary artery is more frequently found in adult hearts than in fetal hearts, concluding thereof that it develops only after birth.The third coronary artery often anastomoses with the branch of the anterior interventricular branch and forms Vieussens' arterial ring.This ring represents a significant path of collateral bloodstream under conditions of coronary insufficiency (,,).There have been described cases of anastomosis of conal artery with diagonal branch of the left conal artery (), also with branches of the right conal artery ().In patients with occlusive illness of coronary arteries, it is also necessary to perform selective angiography of the third coronary artery.This represents the way of detecting anastomoses of this artery with branches of other arteries that remained unnoticed in usual angiographies of the left or right coronary artery (,).Awareness of the presence and distribution of supernumerary coronary arteries is significant for proper interpretation of coronary angiograms, evaluation of seriousness and result of coro-nary insufficiency, and adequate planning and performing surgical myocardium revascularisation ().Th e objective of this paper is to establish presence of supernumerary coronary arteries which arise directly from aorta, their frequency, fl ow, way of branching and possibly their anastomoses with other coronary arteries.

Material and Methods
 adult human hearts were used as material.Th e dissection enabled us to show heart arteries, place of their arising, fl ow, way of branching and present anastomoses.Th e hearts were preserved - days in  formalin solution.Adipose tissue was eliminated and coronary arteries and their branches prepared by careful dissection.In cases where presence of the third coronary arteries was established, the aorta was opened by its length at the level of rear sinus in order to get insight into the left and right aortic sinus and presence of corresponding coronary orifi ces.Radius of these orifi ces was measured and also their distance from the orifi ce of the right coronary artery.

Results
Eight out of  examined hearts () had conal artery (Figure ).It arouse from the right aortic sinus, and its orifi ce, in all cases, was in front of and left from the orifi ce of the right coronary artery.Radius of the orifi ce of the third coronary artery was - mm, and its distance from the orifice of the right coronary artery  to  mm.One heart () had four coronary arteries.Both supernumerary coronary arteries arouse from the right aortic sinus with orifi ce radius from , to , mm (Figure ).Th e third coronary artery passed through the adipose tissue of the coronary groove and reached the pulmonary cone where it most frequently divided in two ending branches.In one case, the third coronary artery was divided in two branches, one of which went to pulmonary cone, while the other was very long and descended along the front side of the right ventricle (Figure ).
In cases with two hearts, the third coronary artery anastomosed with the anterior intraventricular branch and formed the Vienssens arterial ring (Figure ).Conal branch which started from the proximal part of the right coronary artery had a similar fl ow, number of branches and way of branching as the third coronary artery (Figure ).We did not ascertain any anastomoses of the conal branch of the right coronary artery with other arteries.

Discussion
Many authors have studied the blood vessels, their variations and abnormalities.Number of coronary artery variations is relatively frequent and these variations may have related clinical consequences.Here have been described cases of decreased number of coronary arteries, i.e. presence of a single coronary artery arising from the left (, ) or the right (, ) aortic sinus.Presence of single coronary artery may be related with creation of congestive heart failure or myocardial infarction ().Supernumerary coronary artery arises mostly from the right aortic sinus.Literature uses different terms for identifying this artery: conal artery, preinfundiblar or supernumerary right coronary artery (, , ).According to our opinion, the most suitable term for this artery in order to separate it clearly from the conal branch of the right coronary artery, is the third coronary artery.Data about frequency of the third coronary artery are rather diverse, from , and  as stated by Lo () and Kurija () even to  as stated by Hadžiselimović ().In this study, the third coronary artery was found in  of tested cases what is consistent with the results received by Villanoga () and Yamagishi ().Hadžiselimović () points out that even three coronary arteries may arise independently from the right aortic sinus what was confi rmed by this study too.Four coronary arteries were found in one case, where both supernumerary arteries arose from the right aortic sinus.Literature describes cases with anastomosis of the coronary artery with the front interventricular branch, diagonal, circumfl ex one, as well as with the branches of the right coronary artery (,,,).However, this study ascertained solely anastomosis of the third coronary artery with the anterior interventricular branch with formation of Vieussens' arterial ring.Th is arterial ring may be formed by the conal branch of the right coronary artery, but it is less significant, as it is more often enfolded with atherosclerotic process ().In our material we did not found Vieussens' ring with conal branch in its formation.

Conclusion
Th e most suitable term to identify supernumerary heart artery which arises independently from the right aortic sinus is the third coronary artery.Frequency of the third coronary artery is  of examined cases.Th e third coronary artery represents a signifi cant path of collateral coronary circulation as it often anastomoses with the anterior interventricular branch.