SAN artery

It is commonly a single branch arising from the proximal RCA (right SAN artery) or LCx  (left SAN artery). In a few cases, it may originate from both the RCA and LCx (10–13).  Regardless of its artery of origin, the SAN artery usually courses along the anterior interatrial groove toward the superior cavoatrial junction.

Mode of termination of the SAN artery

At the cavoatrial junction, the course of the SAN artery becomes variable and may extend either anteriorly (precaval) or posteriorly (retrocaval), or uncommonly both anteriorly and posteriorly, around the cavoatrial junction (pericaval) to enter the node (12–14).

S-shaped posterior SAN artery

This is an anatomic variant of the SAN artery originating from the posterolateral part of the LCx below or behind the left auricle (8). Having a long S-shaped course,  it supplies the SAN and surrounding area, the left atrium, a large part of the interatrial septum, the right atrium, and sometimes part of the AVN area (15,16).

AVN artery

It is a single artery arising from distal RCA at the level of the crux of the heart in most patients. In the rest, it originates from the distal LCx, or uncommonly from both the RCA and LCx. The artery provides branches to the posterior interventricular septum, interatrial septum, AVN, and penetrating bundle (17–19). 

Left Kugel anastomotic artery

Arising from the proximal LCx, it is part of the large atrial periaortic anastomotic branches between the right and left coronary trunks, described by Kugel (20). This artery is uncommon but sometimes an important collateral between the proximal LCx and whatever artery supplies the crux of the heart (distal RCA or distal LCx). Passing in the interatrial septum, it has several perforating branches, some of which lead directly to the AVN (21,22).

Right Kugel anastomotic (superior descending) artery.

This also is part of large atrial periaortic anastomotic branches between right and left coronary trunks.  The vessel penetrates the right atrial septum anterior to the fossa ovalis and supplies the bundle of His and the AVN and may anastomose with distal branches of the RCA or LCx to complete an intercoronary connection (23–26).    

First septal perforating artery

This is a branch of the left anterior descending artery and supplies the basal septum, with branches to the conduction system, including the bundle of His and proximal bundle branches (27–29). It is not a primary source to the AVN. 

Single SAN artery from RCA

67 

66% (56.8%, 75%)

Single SAN artery from LCx

28 

28% (19%, 36.7%)

Dual SAN supply

6 

6% (1.4%, 10.6%)

Right SAN artery takeoff

0–40 mm 

16 mm ± 7 (14.3 mm, 17.7 mm) 

Left SAN artery takeoff

2–35 mm 

12 mm ± 6 (10.2 mm, 14.4 mm) 

Precaval SAN artery termination

43 

42.5% (33%, 52%)

Retrocaval SAN artery termination

48 

47.5% (37.8%, 57%)

Pericaval SAN artery termination

10

10% (4%, 15%)

 S-shaped posterior SAN artery

6

6% (1.4%, 10.6%)

Right AVN artery

89

87% (80.4%, 93%)

Left AVN artery

11

11% (4.9%, 17%)

Dual AVN arteries

2

2% (0.7%, 4.7%)

Left Kugel anastomotic artery

2

2% (0.7%, 4.7%)

 Right Kugel anastomotic artery

6

6% (1.4%, 10.6%)

Sow et al (13,17)

65

24

11.

84

13

3

Futami et al (30)

73

3

23

80

10

10

Vieweg et al(31)

53

35

11

84

8

8

DiDio LJ et al (32)

58

42

0

NA

NA

NA

Hadziselimovic (33)

60

40

0

85

13

2

Busquet et al(14)

66

30

4

NA

NA

NA

Present study

66

28

6

87

11

2