About the origin of the sinus node artery.

Dear Editor, The interesting comment of the authors [1] raises some remarkable questions concerning our work about the common origin of SN and LCX arteries [2]. Trying to resolve any unclear issues we have to underline the following: First of all we did not describe a combined anatomical abnormality as the authors [1] implied (an underdeveloped LCX with common origin with SN artery). It is obvious in post mortem coronary angiography [2] that the LCX is smaller than the RCA and not in comparison with SN artery. Furthermore our point is not to compare the size between the LCX and SN artery as the authors of ref. [1] incorrectly reported. This is a traditional knowledge and it is not questioned in our report [3,4]. On the contrary, our intention was to stress out the unique finding of the abnormal origin of the SN and LCX with a common trunk from the (LM) coronary artery. In post mortem coronary angiography [2] there are impressive information concerning the course of SNand LCXarteries, but details about their origin are insufficient. In Fig. 1 of the anatomical specimen provided [2] it is clearly shown the LMand the opening of the very short common artery. The 3.1mm is the length of the common trunk which was subjected to several histopathological procedures (cannulation, resection) and not the proximal segment of the SN artery. As it is shown in this anatomical photo the only possiblemistake that someone could have done,was to believe that the LCX originated from the SN but not the opposite. In that case it would be logical to support that 3.1mmwas the length of segment of LCX artery proximal to SNartery and not a common trunk. Finally the growing progress in non-invasive imaging modalities like coronary CT angiography has established their use in pre mortem detection of anomalies involving asymptomatic abnormal origin but normal course of the coronary arteries which are probably less common than anomalies involving abnormal course [5,6]. However pathology and post mortem coronary angiography allows the precise characterization and accurate identification and description of origin and course of the coronary arteries [7].