Keywords
Epigastric arteries - Regional anatomy - Koreans - Breast reconstruction
INTRODUCTION
The use of lower abdomen tissue for breast reconstruction was first described by Holmstrom
in 1979 as a free flap, and was made popular by Hartrampf in 1982, who envisioned
its utility as an abdominal island flap [1]
[2]. Upon advances in the microsurgical skills of surgeons, the abdomen tissue flap
eventually evolved to the deep inferior epigastric perforator (DIEP) flap, which consists
of skin and subcutaneous fat, and which has been demonstrated to decrease donor morbidity
in terms of abdominal muscle impairment. Although the DIEP flap offers many advantages,
intramuscular pedicle dissection is tedious, and it still requires excision of the
abdominal fascia, which may cause prolonged hospital stays or donor site complications
such as hernia [3]
[4].
After the anatomy of the superficial inferior epigastric vessels was first studied
in detail by Taylor and Daniel [5] in 1975, the utility of the superficial inferior epigastric artery (SIEA) flap for
autologous tissue breast reconstruction started being reported in western literature
in the early 1990s [6]. The minimal donor site morbidity in terms of abdominal wall weakness is owing to
the fact that the abdominal wall muscle is intact during the SIEA flap procedure.
However, there are also major disadvantages of the SIEA flap, including the inconsistent
vascular pedicle anatomy and small diameter of the vascular pedicle for the free flap
transfer of the whole abdominal tissue [7].
Previous studies about the SIEA anatomy have been mainly focused on Caucasian patients
or human cadavers, and data on Asian patients are still lacking [8]
[9]. Thus, the purpose of the present study was to assess the anatomy of the superficial
inferior epigastric vessels and to investigate the possibility and reliability of
the SIEA free flap applied for reconstructive breast surgery in Korean female patients.
METHODS
Thirty-two Korean female patients who had undergone autologous tissue breast reconstructive
surgery with free transverse rectus abdominis musculocutaneous (TRAM) flap immediately
after mastectomy between April 2013 and October 2013 were enrolled in the present
study.
Patients with underlying disease or general conditions that may have affected the
vascular state, including hypertension, diabetes mellitus, atherosclerosis, obesity
with severe risk of co-morbidities (body mass index [BMI]>30 kg/m2, according to World Health Organization guidelines for Asian populations [10]), history of smoking, or bleeding tendency, were excluded from the study. Moreover,
patients with a history of Cesarean section, laparoscopic surgery, or liposuction
were also excluded from this study to preclude the effect of these treatments on the
vascular system of the lower abdomen. All patients were fully informed of the study
and provided informed consent to participate. All procedures were performed under
the approval of the institutional review board of our hospital (IRB number, 1303-021-471)
and in accordance with the Declaration of Helsinki.
All dissecting procedures were performed by one experienced plastic surgeon under
2.5× magnifications using a surgical telescope (Looks Corporation, Seoul, Korea).
The patients were laid in the supine position, and the midline of the symphysis pubis
(SP) and bilateral anterior superior iliac spine (ASIS) was marked on the surface
of the patients' bodies. A conventional TRAM flap design was performed, independent
of the location of the anatomical landmarks. The flap was a transversely elliptical
shape superior to the inguinal ligament, including the umbilicus on midline at the
upper incision line and the bilateral ASIS area. The vertical width was determined
based on the possibility of primary closure of the donor tissue and requirements of
the breast volume to be reconstructed. A Doppler probe was utilized to identify the
major perforators of the DIEA, and its course. The lower abdominal incision was first
made without infiltration of lidocaine or epinephrine in order to minimize any vasoactive
effects. At the level of the lower abdominal incision of the TRAM flap, meticulous
dissection was performed to discover the SIEA and superficial inferior epigastric
vein (SIEV). An electrocoagulator was limitedly used to ensure hemostasis, and 4%
lidocaine (Huons Corporation, Seoul, Korea) was applied around the vessels to avoid
vessel spasm ([Fig. 1]).
Fig. 1
The superficial inferior epigastric vesselsThe superficial inferior epigastric artery
(lateral) and superficial inferior epigastric artery vein (medial) revealed at the
lower abdominal incision level.
At first, the existence of the SIEA and SIEV was documented along with the pulsation
status of the SIEA. Next, the relative locations of the SIEA and SIEV were measured,
and compared with the midpoint (M point) connecting the SP and ASIS. The measurements
were defined as positive when located lateral to the M point, and negative when located
medially. Finally, the external diameters and depth from the skin of the SIEA and
SIEV were calculated using a Castroviejo caliper (Storz, Bausch & Lomb Corporation,
New York, NY, USA) ([Fig. 2]). The vessels were ligated after the measurements on the anatomy of SIEA and SIEV
were completed, and followed by TRAM free flap elevation as per standard protocol.
During the operation, the patients' systolic blood pressures were set to 100 mm Hg
on average, and no intraoperative anesthetic event was reported.
Fig. 2
Gross anatomical landmarks for measurementThe anterior superior iliac spine (ASIS),
symphysis pubis (SP), and midpoint (M) are marked. From the midpoint, the locations
of the vessels were identified. When the vessel is located lateral to the M point,
+ is expressed. When the vessel is located medial to the M point, - is expressed.
SIEA, superficial inferior epigastric artery; SIEV, superficial inferior epigastric
vein.
The distances of the SIEA and SIEV from each other and from the M point were investigated.
Unpaired t-test and Mann-Whitney test were used to determine the differences in how
far the vessels were located from the midpoint, laterally or medially. A P-value <0.05
was considered statistically significant. Statistical analysis was performed using
SPSS software ver. 20.0 (IBM Co., Armonk, NY, USA).
RESULTS
At the time of surgery, the mean age of the study patients was 43.46 years (range,
30-70 years), and the mean BMI was 22.45 kg/m2 (range, 17.97-28.93 kg/m2).
The measurements obtained from 64 hemi-abdomen dissections revealed the presence of
the SIEA and SIEV in 48 (75.00%) and 63 cases (98.44%), respectively. Of the total
48 SIEAs, pulsation was observed in 44 cases (91.67%). At least one SIEA was absent
in 12/32 patients (37.50%), and 4/32 patients showed bilateral absence of the SIEA
(12.50%). In 4 cases, the absence of pulsation was observed when the external diameter
of the SIEA was less than 1 mm. On the right side, SIEAs were present in 21/32 cases
(65.63%), while 27 cases of SIEAs were found on the left side (84.38%). However, the
difference in the presence of the SIEA between the two sides was not statistically
significant (P=0.086). The SIEV was found in 31 cases out of 32 on the right side
(96.88%), and present in all cases on the left side (100%).
On average, the SIEA was located 5.79 (±12.87) mm lateral to the M point, whereas
SIEV was located 8.14 (±15.24) mm medial to the M point. Based on the M point, the
tendency of lateral existence of the SIEA and tendency of medial existence of the
SIEV were statistically significant (P<0.001). On the right side, the SIEA was relatively
adjacent to the M point (3.78±10.96 mm) compared with that on the left side (7.35±14.18
mm).
The average distance between the SIEA and SIEV was 17.64 (±12.81) mm; 23/48 cases
showed a distance of less than 15 mm, 18 cases showed a distance between 15 mm and
30 mm, and 7 cases showed a distance of more than 30 mm.
The external diameters of the SIEA and SIEV were 1.20 (±0.39) mm and 1.37 (±0.33)
mm, respectively, and showed no statistical differences between the right and left
sides. The mean caliber of the SIEA on the right side was 1.20 (±0.34), and that of
the left side was 1.20 (±0.44) (P=0.967), while the SIEV on the right and left sides
were 1.36 (±0.35) and 1.38 (±0.32) (P=0.872), respectively. Fifteen hemiabdomens (31.25%)
showed a relatively large caliber of the SIEA (larger than 1.5 mm), while 18 (37.5%)
and 15 (31.25%) hemiabdomens showed an SIEA caliber between 1.0 mm and 1.5 mm, and
less than 1.0 mm, respectively.
The SIEA and SIEV were found above the Scarpa's fascia in all cases. Whether they
were present or not, the SIEA and its two vena comitantes were more commonly identified
in the deep subcutaneous tissue compared with the SIEV. The average depth of the SIEA
from the skin was 9.75 (±2.67) mm, and that of SIEV was 8.33 (±2.65) mm. On the right
and left sides, the SIEA was located at a mean depth of 9 (±2.36) mm and 10.32 (±2.79)
mm, respectively, whereas the SIEV was found at a depth of 8.28 (±2.62) mm on the
right side, and 8.38 (±2.72) mm on the left side. The depths of the SIEA showed no
statistical differences between the right and left sides (P=0.123), and those of the
SIEV revealed same results (P=0.901) ([Tables 1], [2]).
Table 1.
Location, diameter, and depth of the superficial inferior epigastric vessels
|
Variable
|
SIEA
|
SIEV
|
|
Rt. SIEA (SD)
|
Lt. SIEA (SD)
|
Total (SD)
|
Rt. SIEV (SD)
|
Lt. SIEV (SD)
|
Total (SD)
|
|
All units are given in millimeters. When the vessel is located lateral to the M point,
+ is expressed. When the vessel is located medial to the M point, – is expressed.
Rt., right; SIEA, superficial inferior epigastric artery; SD, standard deviation;
Lt., left; SIEV, superficial inferior epigastric vein.
|
|
Location
|
+3.78 (10.96)
|
+7.35 (14.18)
|
+5.79 (12.87)
|
–8.42 (16.37)
|
–7.88 (14.33)
|
–8.14 (15.24)
|
|
Diameter
|
1.20 (0.34)
|
1.20 (0.44)
|
1.20 (0.39)
|
1.36 (0.35)
|
1.39 (0.32)
|
1.37 (0.33)
|
|
Depth
|
9.00 (2.36)
|
10.32 (2.79)
|
9.75 (2.67)
|
8.28 (2.62)
|
8.38 (2.72)
|
8.33 (2.65)
|
Table 2.
Anatomical value of the SIEA and representative parameters that support the merit
of SIEA flaps for breast reconstruction in 64 hemi-abdomens
|
Parameters
|
Number
|
Percentage (%)
|
|
Overall presence of SIEA was 75% (48/64).
SIEA, superficial inferior epigastric artery; SIEV, superficial inferior epigastric
vein.
|
|
SIEA presence
|
48/64
|
-
|
|
Diameter > 1.5 mm (mean: 1.2 mm)
|
15/48
|
31.25
|
|
Pulsation
|
44/48
|
91.67
|
|
SIEA lateral to M point (mean: 5.79 mm)
|
|
|
|
< 5 mm
|
26/48
|
54.17
|
|
5–10 mm
|
7/48
|
14.58
|
|
> 10 mm
|
15/48
|
31.25
|
|
SIEA-SIEV distance (mean: 17.64 mm)
|
|
|
|
< 15 mm
|
23/48
|
47.92
|
|
15–30 mm
|
18/48
|
37.50
|
|
> 30 mm
|
7/48
|
14.58
|
|
Diameter > 1.5 mm with pulsation, < 10 mm lateral to the M point, and SIEA-SIEV <
30 mm
|
7/48
|
14.58
|
DISCUSSION
The SIEA originates from the femoral artery inferior to the level of the inguinal
ligament, and runs toward the superolateral side of the lower abdomen. It is located
in the subcutaneous tissue above Scarpa's fascia as it ascends beyond the inguinal
ligament. The branches of the SIEA communicate with the intercostal arteries and circumflex
iliac arteries laterally, and with the deep inferior epigastric system medially [2]
[11]
[12]. The dominant blood circulation to the lower abdomen originates from the musculocutaneous
perforators supplied by the deep inferior epigastric system, and the superficial inferior
epigastric system based on the subdermal vascular network has a mutual relationship
with the deep inferior epigastric system [12].
To reduce donor site morbidities, the lower abdominal flaps used for reconstructive
breast surgery have been evolved from muscle sparing TRAM or DIEP to SIEA flaps [7]. The SIEA flap does not sacrifice the fascia of the rectus abdominis muscle, and
allows the operation time to be reduced due to its relatively easy pedicle dissection.
Since 1991, when Grotting [13] first introduced the free SIEA flap for reconstructive breast surgery, it has been
the first choice for breast reconstruction by many surgeons [14]
[15].
Despite of the definite advantages of the SIEA flap, its clinical use is somewhat
limited because of the anatomical variability of the SIEA. Taylor and Daniel [5] first evaluated the anatomy of the SIEA in cadavers, and since then, numerous studies
have been conducted on the anatomy of the SIEA and the clinical usability of the SIEA
flap. These studies, which consisted of clinical operative dissection, clinical operative
imaging or perfusion, cadaveric dissection, and cadaveric imaging studies, reported
the presence of SIEA in between 30%-100% of cases; and the average diameter of the
SIEA was found to differ according to the study type and level of measurement, ranging
between 0.6 to 2.9 mm ([16]
[17]
[18]
[19].
Table 3.
Literature review
|
Reference (year)
|
Country
|
N
|
Type
|
Site
|
P of A (%)
|
P of V (%)
|
Pulsation (%)
|
D of A (mm)
|
D of V (mm)
|
L of A (mm)
|
L of V (mm)
|
|
When the vessel is located lateral to the M point, + is expressed. When the vessel
is located medial to the M point, – is expressed.
N, the number of hemi-abdominal specimens; Type, the study modality type, and site
indicates the level of measurement; P of A, presence of the SIEA; P of V, presence
of the SIEV; D of A, diameter of the SIEA; D of V, diameter of the SIEV; L of A, location
of the SIEA away from the M point; L of V, location of the SIEV away from the M point;
COD, clinical operative dissection; LAI, lower abdominal incision; NR, not recorded;
IL, inguinal ligament; Or, origin; CIP, clinical imaging or perfusion study; CD, cadaveric
dissection; SIEA, superficial inferior epigastric artery; SIEV, superficial inferior
epigastric vein.
|
|
Present study (2014)
|
Korea
|
64
|
COD
|
LAI
|
48/64 (75)
|
63/64 (98)
|
44/48 (91.67)
|
1.2
|
1.37
|
+5.79
|
–8.14
|
|
Herrera et al. (2010)
|
USA
|
64
|
COD
|
LAI
|
51/64 (80)
|
64/64 (100)
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Gusenoff et al. (2008) [21]
|
USA
|
64
|
COD
|
LAI
|
52/64 (81)
|
63/64 (98)
|
NR
|
1.7
|
2.9
|
NR
|
NR
|
|
Spiegel et al. (2007) [1]
|
USA
|
278
|
COD
|
LAI
|
160/278 (58)
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Selber et al. (2008) [3]
|
USA
|
638
|
COD
|
LAI
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Vega et al. (2006) [24]
|
USA
|
62
|
COD
|
LAI
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Chevray et al. (2004) [14]
|
USA
|
47
|
COD
|
LAI
|
23/47 (49)
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Dorafshar et al. (2010) [6]
|
USA
|
143
|
COD
|
IL
|
NR
|
NR
|
NR
|
0.96
|
2.27
|
NR
|
NR
|
|
Ulusal et al. (2006) [8]
|
Taiwan
|
44
|
COD
|
Or
|
23/44 (52)
|
NR
|
NR
|
2
|
2.7
|
NR
|
NR
|
|
Arnez et al. (1999)[15]
|
Slovenia
|
20
|
COD
|
Or
|
12/20 (60)
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Stern et al. (1992) [16]
|
USA
|
31
|
COD
|
Or
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Holm et al. (2007) [25]
|
Germany
|
84
|
CIP
|
LAI
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
|
Rozen et al. (2009) [20]
|
Australia
|
500
|
CIP
|
NR
|
468/500 (94)
|
500/500 (100)
|
NR
|
0.6
|
NR
|
NR
|
NR
|
|
Fathi et al. (2008) [22]
|
Iran
|
40
|
CD
|
IL
|
38/40 (95)
|
40/40 (100)
|
NR
|
1.45
|
2.14
|
Within ± 10 (33/38, 87%)
|
Within ± 10 (35/40, 88%)
|
|
Rizzuto et al. (2004) [19]
|
USA
|
100
|
CD
|
IL
|
72/100 (72)
|
NR
|
NR
|
1.6
|
NR
|
NR
|
NR
|
|
Reardon et al. (2004) [2]
|
Ireland
|
22
|
CD
|
Or
|
20/22 (91)
|
21/22 (95)
|
NR
|
1.9
|
2.1
|
Within ± 10 (15/20, 75%)
|
NR
|
|
Taylor et al. (1975) [5]
|
Australia
|
100
|
CD
|
Or
|
65/100 (65)
|
NR
|
NR
|
1.4
|
NR
|
NR
|
NR
|
|
Schaverien et al. (2008) [23]
|
USA
|
24
|
CD
|
NR
|
8/24 (33)
|
NR
|
NR
|
NR
|
NR
|
NR
|
NR
|
According to Rozen et al. [20], cadaver studies are limited due to the post-mortem changes in vascular anatomy,
and the fact that the physiologic features of vessel cannot be assessed, although
complete exposure and meticulous dissection is possible. Imaging studies have several
advantages, such as non-invasiveness, large cohorts, and being able to evaluate the
dynamic perfusion to the lower abdominal tissue [17]. However, accurate measurements of the vessel diameter or the presence of SIEA pulsation
is difficult, and the complicated vasculature of the lower abdomen can interfere with
these studies. On the other hand, clinical dissection studies have revealed substantial
physiologic vascular anatomy, and have provided direct information when determining
the optimal type of abdominal flap. These studies also have limitations in terms of
incomplete exposure of the vascular anatomy, which is confined to the surgical field,
owing to ethical problems associated with the prolonged operation time [1]
[6]. Furthermore, the intraoperative decision of a pedicle between the SIEA and DIEA
should be made according to the status of the SIEA at lower abdominal incision level,
not according to the external diameter of the SIEA at the level of origin [19]
[21]
[22].
Spiegel and Khan [1] created an intraoperative algorithm for breast reconstruction, and recommended using
the SIEA flap only if the diameter of the SIEA was >1.5 mm at the lower abdominal
incision level, as SIEAs with a diameter of <1.5 mm showed higher rates of fat necrosis
and partial flap loss due to arterial thrombosis. They also found higher incidences
of arterial thrombosis at the point of kinking as the SIEA entered the flap during
re-exploration. Of note, the pedicle enters into the subcutaneous border of SIEA flaps,
whereas it enters into the inferior surface of TRAM and DIEP flaps [23]. The kinking can result in narrowing of the pedicle, and increase the risk of vascular
compromise; therefore, the diameter at the entry point into the flap is more important
than the diameter at the origin ([Fig. 3]).
Fig. 3
Anatomy of vascular pedicles entering the flapsComparison of the vascular pedicles
between the transverse rectus abdominis musculocutaneous flap (A) and superficial
inferior epigastric artery flap (B). In the superficial inferior epigastric artery
flap, vascular pedicles which enter the flap can be kinked (graphically described
as *on the Fig. B), therefore the blood flow at the kinking point becomes slow, and the
risk of vascular compromise increases.
We believe that the present study is of substantial clinical importance, as, to our
knowledge, this is the first clinical study about the anatomy of the SIEA in Asian
females. In Taiwan, Ulusal et al. [8] reported that the mean diameters of the SIEA and SIEV were 2.0 mm and 2.7 mm, respectively.
While their study was also a clinical study, the values were selectively obtained
when the SIEA flaps were chosen for breast reconstruction at the level of origin.
In the present study, we examined the diameters of the SIEA and SIEV at the level
of the lower abdominal incision, which may provide more helpful information in deciding
the optimal flap type [8].
There are four major factors to take into account when the SIEA flap is favored for
reconstructive breast surgery. First, the external caliber of the SIEA should exceed
1.5 mm at the level of the lower margin of the flap [3]
[6]
[15]
[17]
[20]
[22]
[24]. Second, the pulsation of the SIEA should be visible to the naked eye [1]
[6]
[14]. Third, a more medial position of the SIEA from the midline should be guaranteed,
because the SIEA supplies a lesser territory of the flap across the midline [2]
[17]
[20]
[25]. Forth, proximity of the SIEA with the SIEV is an essential factor to allow the
use of both vessels as the same recipient vascular pedicle for microanastomosis [2]
[17]
[25]. The data of the present study were analyzed according to these criteria. We found
that only 14.58% (7/48) of the hemiabdomens met all criteria, including a SIEA larger
than 1.5 mm in diameter with pulsation, a relatively medial position away from the
M point, and an approximate distance to the SIEV of less than 30 mm ([Table 2]).
The relatively low BMI and small volume of abdominal tissue of Korean women may reduce
the pressure burden of the flap on the vascular pedicle. Moreover, Korean women also
have relatively small breasts; and therefore, a SIEA flap may represent a good option
when whole abdominal tissue is not required. The relative small caliber of the SIEA
is compatible with the perforator of the internal mammary artery [12], and preoperative imaging and Doppler sonographic tracing on the inferior epigastric
vessels of both the deep and superficial systems will provide additional clues in
determining the optimal type of flap.
Based on the literature review, we considered that a SIEA larger than 1.5 mm in diameter
is reliable as a vascular pedicle. However, most of studies represent the value of
western populations, and the value may differ from that of Asian populations. Therefore,
further studies are needed to set new safety criteria for the Asian patients.
In conclusion, the vascular anatomy favoring SIEA flaps for breast reconstruction
was found in only 14.58% of cases (7/48). Therefore, careful preoperative assessment
on the lower abdominal vasculature and strict indication for SIEA flaps are required
to achieve successful breast reconstruction using SIEA flaps in Asian patients. Large-scale
data of the SIEA and clinical results of breast reconstruction using SIEA flaps are
warranted in future studies.
