Int J Anat Res 2014, 2(4):740-43. ISSN 2321-4287 740
CASE REPORT
ATYPIC DRAINAGE PATTERN OF POSTERIOR INTERCOSTAL VEINS
INTO THE AZYGOS VENOUS SYSTEM
Rimpi Gupta *
1, Deepak Goyal
2, APS Batra
3, Shveta Sw ami
4.
ABSTRACT
Address for Correspondence: Dr. Rimpi Gupta, M BBS, M S Anat omy, Assistant professor, Dept . of Anatomy, BPS GM C For Women, Khanpur Kalan, Sonipat , India. E-M ail: dr.rimpigupta15@gmail.com
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* 1 Assistant professor, Dept of Anat omy, BPS GM C For Women, Khanpur Kalan, Sonipat , India. 2 M edical officer HCM S-1, PHC Dubhet a,Dist Sonepat , Haryana, India.
3 Professor & Head, Dept of Anat omy, BPS GM C For Women, Khanpur Kalan, Sonipat , India. 4 Associate professor, Dept of Anat omy, BPS GM C For Women, Khanpur Kalan, Sonipat , India.
The azygos venous syst em vary great ly in t heir m ode of origin, course,t ribut aries, anast om oses and t erm inat ion w hich resulst predom inant ly due t o it s com plex em bryological developm ent . Azygos venous syst em develops as right and left azygos venous lines. Right azygos venous line develops int o vert ical part of azygos vein w her eas t he left one develops int o accessory hem iazygos and inf er ior hem iazygos veins. These are connect ed by subcentral/ t ransvertebral veins. In t he present case, w e found an at ypic drainage pat t ern of posterior int ercost al veins int o azygos venous syst em , left being m or e var iable. Right superior int ercost al vein form ed by 2nd and 3rd
post erior int ercost al veins w her eas left superior int ercost al vein w as found t o be absent . 2nd, 3rd, 4t h & 5t h left
post erior int ercostal veins t hus drained int o accessory hem iazygos vein. Sixt h and sevent h left PICVs form ed a com m on t runk w it h accessory hem iazygous vein and drained int o t he azygous vein at T6 level. Eight h one unit ed w it h t he hem iazygos vein and form ed a com m on t runk w hich drained int o azygos vein at T8 level. Such variat ions of t he azygos venous syst em are im port ant for a clinician during m ediast inal surger ies t o pr event inadvert ent hem or rhagic com plicat ions.
KEY W ORDS: Azygos vein, accessor y hem iazygos vein, hem iazygos vein, superior int ercost al vein.
INTRODUCTION
Int ernat ional Journal of Anatomy and Research,
Int J Anat Res 2014, Vol 2(4):740-43. ISSN 2321- 4287 DOI: 10.16965/ ijar.2014.537
Received: 13 Nov 2014
Peer Review : 13 Nov 2014 Published (O):31 Dec 2014 Accept ed: 02 Dec 2014 Published (P):31 Dec 2014 Internat ional Journal of Anat omy and Research
ISSN 2321-4287 w w w.ijmhr.org/ ijar.ht m
DOI: 10.16965/ ijar.2014.537
Variat ions related t o azygos venous system are not rare [1]. They vary much in t heir mode of or igin, course, t ribut er ies, anast om osis and t erminat ion. Azygos veins are import ant caval-caval and port ocaval-caval junct ions, t hus form ing collat eral circulat ion in caval vein occlusion and in port al hypertension [2]. Several variat ions are report ed in t he lit erat ure viz agenesis of acces-sory hemiazygos vein w it h a predominant left superior int ercost al vein draining t he upper int ercost als spaces, agenesis of hemiazygos
Int J Anat Res 2014, 2(4):740-43. ISSN 2321-4287 741 Rimpi Gupt a et al.. ATYPIC DRAINAGE PATTERN OF POSTERIOR INTERCOSTAL VEINS INTO THE AZYGOS VENOUS SYSTEM .
venous syst em can easily be confused w it h pat hological condit ions such as aneur ysm s, t umors and enlarged lymph nodes [3]. Finally, it is of ut most importance for surgeons t o keep in mind t he possibilit y of a variat ion of t he azygos venous syst em during t he m ediast inal opera-t ions.
CASE REPORT
During t he rout ine undergraduat e dissect ion of t he post erior mediast inum of 55 year old male cadaver, w e encountered an unusual variat ion in t he drainage pat t ern of post erior int ercost al veins (PICVs), left being more variable in t heir mode of drainage. In t he present case, t he right second and t hird PICVs formed t he superior ICV and drained int o t he arch of t he azygos vein whereas the fourth PICV drained directly into t he azygous vein. Then five t o eleven right PICVs follow ed t he normal pat tern of drainage into the
azygous vein. Left PICVs show ed much variat ion in t heir mode of drainage. Left superior ICV w as found t o be absent . The second and t hird PICVs w hich normally joins t o form left superior ICV dr ain ed i ndepen den t ly int o t he accesso r y hemiazygous vein. Fourt h and fift h left PICVs d r ai n ed n o r m al ly i n t o t he accesso r y hemiazygous vein. Then t he sixt h and sevent h left PICVs formed a common t runk w hich joined t he accessor y h em i azy go u s v ei n an d t hi s common channel drained int o t he azygous vein at T6 level. Eight h left PICV inst ead of draining int o accessory hemiazyos vein unit ed w it h t he hemiazygos vein and formed a common t runk w hich t hen drained int o azygos vein at T8 level. Nint h, tent h and elevent h left PICVs follow ed normal pat t ern of drainage int o t he hemiazygos vein. The f irst PICVs of bot h sides drained nor m ally int o t he br achiocephalic veins of eit her side.
Fig. 1:Right azygos venous syst em in present case. Fig 2:Accessor y hem iazygos vein in t he present case.
Right SICV
Right Sympat het ic chain
Arch of Azygos vein
Azygos vein
Accessory
hem iazygos vein 2
nd
left PICV
3RD left PICV
4TH left PICV
Int J Anat Res 2014, 2(4):740-43. ISSN 2321-4287 742 Rimpi Gupt a et al.. ATYPIC DRAINAGE PATTERN OF POSTERIOR INTERCOSTAL VEINS INTO THE AZYGOS VENOUS SYSTEM .
Fig. 3:Drainage patt ern of 6t h t o 11t h left post er ior
int ercost als veins (PICVS).
Com mon t runk formed by acc hem iazygos & 6t h, 7t h
left PICVs.
Common trunk formed by 8t h PICV & hemiazygos vein.
DISCUSSION
The azygos venous syst em develops from a pair of longit udinal venous lines, called t he right and left azygos venous line (medial sympathet ic vein line), dorsolat eral t o t he aort a. On each side, t he azygos venous line lies parallel t o anot her t w o parallel primit ive venous lines called t he right and left subcardinal and post cardinal veins. The right azygos venous line develops int o t he vert ical part of t he azygos vein. The arch of t h e azygos i s cont r ib ut ed p ar t iall y b y t he persist ent cephalic part of t he right post erior cardinal vein. The caudal end of each azygos venous line joins w it h t he corresponding sub-cardinal vein close t o t he level of t he int er subcardinal anast omosis. Thus t he azygos vein begins as t he ascending lumbar vein on bot h sides. The fat e of t he left azygos venous line is different . Due t o t he development of an oblique
communicat ion bet w een t he right and t he left ant erior cardiac veins, t he dist al part of t he left ant erior cardinal vein, t he cranial part of t he left post erior cardinal vein and t he left com mon cardinal vein regress great ly. The first of t he t w o st ruct ures ment ioned above persist in t he adult life as left superior int ercost al vein. The left azy go s v eno u s l i n e gi ves r i se t o a set o f longit udinally arranged veins. The upper set , nam ed t he superior or accessory hem iazygos veins, drain t he fourt h t o t he sixt h int ercost als spaces posteriorly. The low er part of t he azygos venous line gives rise t o t he inferior hemiazygos vein t hat arises as t he left ascending lumbar vein, similar t o t he azygos vein on t he right , draining t he sevent h and low er int er cost als spaces. The accessor y hem iazygos and t he hem iazygos veins usually ar e independent systems and connect t o t he azygos vein w it h tw o t ransversely orient ed veins at t he levels of t he sevent h and eight h t horacic veret ebrae. These t ransverse channels embrylogically are derived from such connect ions bet w een t he right and t he left post erior cardinal veins [10].
In t he present case, t he dist al part of t he left ant erior cardinal vein, t he cranial part of t he left post erior cardinal vein w hich norm ally persist as left superior int ercost al vein did not persist leading t o t he non- format ion of left superior int ercostal vein. Hence, t he second and third left PICVs drained int o accessory hemiazygos vein.
CONCLUSION
Though t he anat omical variat ions in t he azygos syst em ar e p h ysi o lo gi cal l y n o r m al , i t i s import ant t o be aw are of t he unique yet normal variat ions of t he azygos venous syst em during m ediast inal surgeries t o prevent inadvert ent hemorrhagic complicat ions [11]. Confusion can be avoided in diagnosing t hese st ruct ures aft er det ect ion in scans and M RI [12,13].
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Conflicts of Interests: None
Int J Anat Res 2014, 2(4):740-43. ISSN 2321-4287 743 Rimpi Gupt a et al.. ATYPIC DRAINAGE PATTERN OF POSTERIOR INTERCOSTAL VEINS INTO THE AZYGOS VENOUS SYSTEM .
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Rimpi Gupta, Deepak Goyal, APS Bat ra, Shveta Swami. ATYPIC DRAINAGE PATTERN OF POSTERIOR INTERCOSTAL VEINS INTO THE AZYGOS VENOUS SYSTEM . Int J Anat Res 2014;2(4):740-743. DOI: 10.16965/ ijar.2014.537
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