Deep inferior epigastric perforator flap: An anatomical study of the perforators – Nguyen Van Phung

Journal of military pharmaco-medicine no5-2018 143 DEEP INFERIOR EPIGASTRIC PERFORATOR FLAP: AN ANATOMICAL STUDY OF THE PERFORATORS Nguyen Van Phung*; Tran Van Anh**; Vu Quang Vinh** SUMMARY Objectives: Deep inferior epigastric artery perforator flaps have become popular worldwide in breast reconstruction to reduce done site morbidity. Isolating perforator vessels challenges most surgeons. The purpose of study was to investigate anatomical vascular of the deep inferior epigastric perforator flap. Subjects and methods: 40 flaps were harvested from 20 fresh adult cadavers. The deep inferior epigastric artery and its perforators were dissected and canularized. Barium sulfate 30% v/w diluted and mixed with blue methylen was injected. Determine details such as perforator size, location and measurements in relation to the umbilicus. Results: 177 perforator vessels dissected from 40 flaps, average 4.4/1 flap. 106 perforators (59,9%) in a medial row with 84 perforators (79,3%) were oblique course. 71 perforators (40,1%) in a lateral row with 51 perforators (71,8%) were rectilinear course. 111 perforators (63,7%) located in a distance of 10 - 40 mm from the umbilicus. The average length and diameter of the dominant perforators was 44.3 ± 13.8 mm and 1 ± 0.1 mm. Conclusion: Understanding the morphological characteristics of the perforator can aid the surgeon in more harvesting safety the deep inferior epigastric artery perforator flap. Two vertical rows of perforator vessels were observed along the anterior rectus abdominal sheath: medial row and lateral row. The perforator presents a rectilinear course usually was in lateral row and easy to dissect than the perforator presents an oblique course. The dominant perforators usually located in a distance of 15 - 40 mm from the umbilicus. * Keywords: Deep inferior epigastric perforator flap; Breast reconstruction. INTRODUCTION The deep inferior epigastric perforator (DIEP) flap is one of the most commonly flaps that was used for reconstruction in plastic surgery due to excellent quality, adequate tissue and soft texture. Especially, middle-aged breast cancer patients usually have excess skin and belly fat that will be suitable materials for breast reconstrucition. In recent decades, the development of DIEP flap has brought new modifications to the conventional abdominal flaps due to less donor-site morbidity and total muscular preservation. The DIEP flap could decrease abdominal bulging or muscular weakness. In addition, the DIEP flap dissected from the rectus abdominis, can increase in pedicle length, which allows better freedom of design. However, identifying the deep inferior epigastric artery (DIEA) and vein is still challenging the surgeons because of variable anatomy of blood vessels in human bodies. Our research aims to: Study on the anatomical characteristics of the inferior arteries that give blood supply for DIEP flat in adult Vietnamese cadavers, that could give useful informations for plastic surgeons in clinical practice. * Hochiminh University of Medicine and Pharmacy Corresponding author: Nguyen Van Phung (ngvaph@cyd.edu.vn) Date received: 10/03/2018 Date accepted: 21/05/2018 Journal of military pharmaco-medicine no5-2018 144 SUBJECTS AND METHODS 1. Subjects. This research was carried out on 20 adult Vietnamese cadavers in Department of Anatomy, Hochiminh University from November 2011 to Juanuary 2016. 2. Methods. The descriptive cross-sectional study. - A 4 cm inguinal incision was made to explore deep epigastric artery. The catheter was inserted to artery to inject contrast agent (barium sulfate 30%) and blue methylen. 24 hours later, we performed surgery to dissect rhombus flap in abdominal wall from umbilicus to anterior superior iliac spine. These flaps were dissected to superficial fascia membranous layer (Scarpa’s fascia) to explore perforator arteries under medical loupes (x3 - 5). After that, we opened the anterior wall of rectus sheath and muscle to identify DIEA. - We determined orginin, branches, diameter, length of deep epigastric inferior arteries and deep epigastric perforator arteries. We also recorded the course of these arteries. - Gross photo and X-ray were taken in all cases. - We analyzed data by statistical software. RESULTS 1. Deep inferior epigastric artery perforator. The DIEA was recognized on both sides of 20 human cadavers and the orgin was a single branch from the external iliac artery. It curved forward in the subperitoneal tissue, and then ascended obliquely along the medial margin of the abdominal inguinal ring; continuing its course upward, it pierced the transversalis fascia and passed in front of the linea semicircularis, ascended between the rectus abdominis and the posterior lamella of its sheath (31/40). The other ateries entered in rectus abdominis muscle (9/40). We found the DIEA divided into 2 main branches in 17 cases, 3 main branches in 2 cases. The other cases had only 1 main branch. The average diameter of DIEA at the orgin was 2.2 ± 0.2 mm and at the lateral boder of the rectus abdominis was 1.9 ± 0.2 mm. The average length of DIEA from the orgin and the lateral boder of the rectus abdominis to the perforator arteries was 14.9 ± 3.5 cm and 10.9 ± 1.1 cm, respectively. 39 cases had 2 veins that went along with DIEA and 1 case had 1 vein. All these veins drained to the external iliac vein. 2. The perforators. In this research, we studied the perforator that ≥ 0.5 mm of diameter in rhombus flap. * Number: There were 177 perforators which divived from 40 orversed DIEA (4.4 perforators per DIEA). The average number of perforators of DIEA that had 1 main branch and 2 main branches were 4.33 and 4.18, respectively. In the DIEA that had 2 main branches, the average number of perforators of lateral branch and medial branch were 2.0 and 2.12, respectively. In 2 cases of the DIEA that had 3 main branches, they had 3 and 4 perforators. Journal of military pharmaco-medicine no5-2018 145 * Location and distribution: In front of retus sheath, the perforators were distributed in 2 lines: the lateral line in lateral one-third of restus abdominis muscle and the medial line in the medial one-third of restus abdominis muscle. There were 106 perforators (59.9%) in the medial line and 71 perforators (40.1%) in the lateral line, of which the number of dominant perforators in each line were 24 (60%) and 16 (40%). If the umbilicus was the O-axis of the XY axis, the average distance from the perforators to the X-axis was 23.8 ± 15.8 mm, the Y axis was 22.5 ± 12 mm. The average distance from the most dominant perforator to the X axis was 16.2 ± 7.1 mm, while the Y axis was 23.4 ± 13.1 mm. Within the circle of the center of the umbilicus, the distribution of the perforators and dominant perforators as shown in table 1: Table 1: Distribution of perforators in scope the bottom half of circle, of which the center was umbilicus. 0 - 2 cm < 2 - 4 cm < 4 - 6 cm < 6 - 8 cm Number of perforators (n = 177) 55 (31.1) 56 (31.6%) 52 (29.4%) 14 (7.9%) Number of dominant perforators (n = 40) 16 (40%) 13 (32.5%) 11 (27.5%) 0 (0%) The average distance from perforators to umbilicus was 34.4 ± 17.2. Most of the perforators were within 10 - 40 mm from the umbilicus. Figure 1: The perforators of DIEA - cadaver number 476. * Length and diameter: In the study, we measured the diameters of the perforators at the origin and the length of the perforators from the point of origin to the point of entry into the superficial fascia. Journal of military pharmaco-medicine no5-2018 146 Table 2: The size of the perforators. Perforators with diameters ≥ 0.5 mm (n = 177) Dominant perforators (n = 40) Average diameter 0.7 ± 0.2 1 ± 0.1 Average length 45.8 ± 11.8 44.3 ± 13.8 Most perforators had relatively short length, including the dominant perforators. The diameter of the perforators was quite small, with most of the perforators less than 1 mm in diameter. Therefore, it was difficult to directly use these perforators for the flap’s blood supply in supermicrosurgery. It could be required to use DIEA together. * The course of perforators: The course of perforators before entering the superficial fascia was recored in two different forms. The first form, a direction of perforator was perpendicular to the distance from the origin to skin flap. For this form, when dissecting to isolate the perforator, we only need to seperate along them without removing muscle, and distance from the flap to DIEA is shorter. The second form, from the origin of perforators with cross direction through muscle to skin flap, it could be outward, inward, downward, or upward. Muscle could be removed when dissecting the cross croner perforator because the distance is longer. The perforators in a medial line with 21 (19.8%) was rectilinear course and with 84 (79.3%) was oblique course. The perforators in a lateral line with 51 (71.8%) was rectilinear course and with 20 (28.2%) was oblique course. The dominant perforators with 23 (57.5%) was rectilinear course and with 17 (42.5%) was oblique course. * The characteristics of perforator in X- ray: The skin flaps were X-rayed and the results showed that the blood supply to the flap was plentiful, with connections between the perforators. The blood supply area of each perforator was dependent on its diameter at the enter point of muscle fascia. Figure 2: The perforators on X-ray - Cadaver 482. DISCUSSION Breast reconstruction following breast cancer surgery is a necessity for patients to improve the quality of life. The suitable breast reconstruction material is always a challenge in clinical study that requires to find a material that adequately meets the regenerative volume, closely relates to the opposite breast and the least affects tissue supply. The DIEP flap is the skin flap that fully filled the above criteria. It was applied clinically by Koshima and Seoda in 1989 firstly. After that, Allen used this flap for breast reconstruction in 1994. Nowadays, DIEP has been used more and more commonly in breast reconstruction [1, 2, 7].. Journal of military pharmaco-medicine no5-2018 147 Despite of many advantages of breast reconstruction, the application of DIEP flap in clinical remains difficult for surgeons due to abnormalities and differences in anatomy such as the course of the DIEA and its perforators, causes obstacles to lift safely. Thus, studying the DIEA and its perforators has always been interesting [5, 8, 9]. There were many studies on this issue, but the results were not consistent. According to Itoh, Boyd, Tansatit, El- Mrakby... the DIEA was divided into 2 branches in most of cases [3, 4, 6, 11]. Meanwhile, according to Nguyen Tran Quynh, the DIEA was not divided into 2 branches but ran straight up in the form of a main body in most of cases. In our study, 52.5% of the cases of DIEA were main body type, which ran up, 47.5% of the cases of DIEA divided into 2 - 3 branches. The number of perforators per DIEA was also reported differently by many authors, depending on how large or short perforators were determined by the diameter of the perforators included in the study, the number of perforators of DIEA for abdominal intervals from 0.8 to 6.8. In our study, examined perforators with diameter of ≥ 0.5 mm were found with an average of 4.4 peforator per DIEA. Itoh and Boyd also examined perforators with diameter of ≥ 0.5 mm but within the umbilicus region with an average of 6.5 and 6.8 perforators per DIEA. In agreement with the other authors, we found that the perforators were distributed in two lines at the entry point of the rectus abdominis: medial and lateral, with 106 (59.9%) and 71 (40.1%), respectively. When osbserving the direction of perforators, we found that perforators in the medial rows were often oblique course in the muscle (79.3%), while in the lateral rows were often rectilinear course (71.8 %), which was consistent with other authors' reports. This was a feature that should be noted for the selection of perforators when lifting the flaps. For the perpendicular perforator, we only need to seperate along them without removing muscle. Muscle could be removed when dissecting the cross croner peforator because the distance was longer. When studying the distance betwwen the entry point of the perforators at the superficial fascia and the umbilicus, we found that the most perforators (62.7%) were located within a radius of 0 - 40 mm with the center of umbilicus, which was consistent with the other authors. The dominant perforator was also concentrated in a radius of 0 - 40 mm with the center of umbilicus (72.5%). The most dominant perforator in our study had an average diameter of 1 ± 0.1 mm (0.8 - 1.2 mm), with an average length of 44.3 ± 13.8 mm. The length from the starting position of the most dominant perforator to the DIEA at the lateral rectus abdominis was 10.9 ± 1.1. CONCLUSION The perforators were in 2 lines along the anterior rectus abdominal sheath: medial and lateral. The perforator presents a rectilinear course usually was in lateral row and easy to dissect than the perforator presents an oblique course. The dominant Journal of military pharmaco-medicine no5-2018 148 perforators usually located in 0 - 40 mm from the umbilicus. Understanding the morphological characteristics of the perforator can help the surgeon in more harvesting safety the deep inferior epigastric artery perforator flap. REFERENCES 1. Nguyen Tran Quynh. Nghiên cứu giải phẫu vạt cơ thẳng bụng trên người Việt Nam, Luận án Tiến sỹ Y học, Trường Đại học Y Hà Nội. 2006, tr.50-77. 2. Allen R.J, Treece P. 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