HAND SURGERY
AND
MICROSURGERY
Perfusion Dynamics of Free DIEP and SIEA Flaps During the First Postoperative Week Monitored With Dynamic Infrared Thermography Louis de Weerd, MD,* A˚shild O. Miland, MSc,†‡ and James B. Mercer, PhD†‡
Abstract: Perfusion dynamics of 16 free DIEP flaps and 4 free SIEA flaps were studied during the first, third, and sixth postoperative day using dynamic infrared thermography (DIRT). For both flap types the zone positioned over the perforator is perfused first, followed by the adjacent ipsilateral zone, and finally the contralateral zones. Perfusion of the subdermal plexus of all zones preceded the perfusion of the subcutaneous layer of all zones. While the initial hyperemia subsided with time, the total number of hot spots increased with time. Perfusion of free DIEP and SIEA flaps during the first postoperative week is a dynamic process. The perfusion shows a stepwise progression at the level of the subdermal plexus and at the level of the subcutaneous layer each with its own time sequence and with the midline as an area of resistance for circulation. Key Words: perfusion, free flap, DIEP, SIEA, infrared thermography (Ann Plast Surg 2009;62: 42– 47)
T
he lower abdomen has become the preferred donor site for microvascular autologous breast reconstruction. This donor site remains unmatched in tissue quality, texture, and quantity for breast reconstruction.1–3 Current methods of microvascular breast reconstruction using this donor site include the free transverse rectus abdominis myocutaneous (TRAM) flap, the deep inferior epigastric perforator (DIEP) flap and the superficial inferior epigastric artery (SIEA) flap. These techniques have evolved in an attempt to reduce morbidity at the donor site.1– 4 Arnezˇ et al4 proposed an algorithm for selection of flaps from the lower abdomen for breast reconstruction to reduce donor site morbidity.4,5 The SIEA flap is associated with the lowest donor site morbidity because muscle and fascia are not injured. With the DIEP flap, muscle and fascia are incised but not harvested, and although donor site complications are possible, these are less frequent than with use of the free TRAM flap. Much has been written about the importance of limiting donor site morbidity.5– 8 However, the attempt to limit donor site morbidity may have consequences for the circulation of the flap and the volume of tissue that safely can be harvested. Current flap design is based on the angiosome concept of Taylor and Palmer.9 Based on anatomic studies they defined an angiosome as a 3-dimensional block of skin and underlying tissue supplied by a single source artery. Angiosomes are interconnected in each layer, whether it be skin, fat, muscle, nerve, or bone, usually by reduced-caliber vessels called “choke vessels.” Taylor and associReceived November 22, 2007 and accepted for publication March 24, 2008. From the *Department of Plastic Surgery and Hand Surgery, †Department of Radiology, University Hospital North Norway, and ‡Department of Medical Physiology, Faculty of Medicine, University of Tromsø, Tromsø, Norway. Reprints: Louis de Weerd, MD, Department of Plastic Surgery and Hand Surgery, University Hospital North Norway, Sykehusveien 38, N-9038 Tromsø, Norway. E-mail:
[email protected]. Copyright © 2008 by Lippincott Williams & Wilkins ISSN: 0148-7043/09/6201-0042 DOI: 10.1097/SAP.0b013e3181776374
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ates9 found that choke vessels in skin flaps behaved like highresistance zones of circulation.9,10 A viable flap can safely incorporate the angiosome supplied by the source artery and often an adjacent angiosome. Necrosis tends to occur in the next or subsequent angiosome. The free TRAM and DIEP flaps are based on the same source artery, the deep inferior epigastric artery. In theory, the TRAM flap as well as the DIEP flap may be composed of the angiosome of the deep inferior epigastric artery (DIEA), the adjacent ipsilateral angiosome, and the adjacent contralateral angiosome. However, the free TRAM flap receives its blood supply from a large number of direct as well as indirect perforators arising from the source artery, while the DIEP flap is supplied by only 1 or 2 direct perforators.11 Studies have indeed shown a more robust blood supply of the free TRAM flap compared with the free DIEP flap, which could be the reason for the increased incidence of fat necrosis reported for DIEP flaps.12,13 It has been recommended to use the DIEP flap for the reconstruction of small breasts or for those breasts that do not require more than 70% of the abdominal flap to achieve adequate volume and shape.13,14 The laterally located angiosome of the SIEA allows, in theory, the safe inclusion of the adjacent and medially located angiosome of the deep inferior epigastric artery but not the angiosome over the midline. According to Granzow et al15 any tissue taken more than 1–2 cm past the midline will often demarcate and necrotize within hours or days after the initial reconstruction. However, others, including Arnezˇ, have reported on the successful use of nearly the entire transverse abdominal flap as a SIEA or DIEP flap for breast reconstruction.16 –18 The anatomic and hemodynamic changes that follow flap elevation ultimately determine the perfusion of the flap and therefore the outcome of free flap surgery. The vascular anatomy of free TRAM, DIEP, and SIEA flaps has been well studied.11,19,20 Hemodynamic studies on free TRAM flaps have been performed, but such studies are limited in free DIEP and SIEA flaps.14,17,21,22 Sheflan and Dinner23 divided the TRAM flap into 4 equal parts and numbered them according to their clinical impression of perfusion. Zoning of the abdominal flap is commonly used in hemodynamic studies.14,17,21 The quality of perfusion decreases from zone I to zone IV. The 4 zones are actually an adaptation of the angiosomes of the superficial and deep epigastric arterial systems as described by Taylor and Palmer.24 A further understanding of the perfusion dynamics of the DIEP and SIEA flaps could permit harvesting of larger flaps and reduction of postoperative complications such as partial flap loss and fat necrosis. In this prospective clinical study, perfusion of free DIEP and free SIEA flaps was monitored during the first postoperative week using dynamic infrared thermography (DIRT). Infrared (IR) thermography is widely used in clinical medicine as a noninvasive technique to measure skin surface temperatures. Salmi et al22 reported on the use of IR thermography for intra- and postoperative monitoring of free TRAM flaps. DIRT is based on the relationship between dermal perfusion and the rate of change in skin surface temperature following transient thermal challenges.25,26 Studies Annals of Plastic Surgery • Volume 62, Number 1, January 2009
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show a good correlation between thermographic and laser Doppler velocimetric results.26,27 DIRT is a noninvasive technique that is used to locate perforators and to assist in flap design.28,29 Wolff et al30 used the technique to examine the perfusion of venous flaps. The aim of our study was to describe the qualitative changes in perfusion of free DIEP flaps and free SIEA flaps during the first postoperative week using dynamic infrared thermography.
MATERIALS AND METHODS Twenty patients, mean age 51 years (range 34 – 65 years) and a mean body mass index of 27.0 kg/m2 (range 20.2–30.5 kg/m2), participated in this study. All patients were scheduled for secondary autologous breast reconstruction with either a free DIEP or free SIEA flap. On the preoperative day, arterial perforator sounds were located with a hand-held Doppler (8MHz, Multi Dopplex II, Huntleigh Healthcare, Cardiff, UK) on the lower abdomen and marked with a permanent marker on the skin. Once the perforators were identified, an abdominal ellipse was drawn using the bilateral anterior superior iliac spines as the transverse limits and the pubic tubercle and the umbilicus as the vertical limits. The flap was divided into 4 equal zones as suggested by Sheflan and Dinner.23 Preoperative IR images of the abdomen were taken after an acclimatization period of 10 minutes at room temperature as well as during rewarming after a cold challenge. The thermal challenge was delivered by blowing air at room temperature over the skin surface for 2 minutes with the aid of a desktop fan. During the operation the algorithm of Arnezˇ was applied.1,4,5 All flaps were anastomosed to the internal mammary artery and vein. If indicated, the contralateral superficial inferior epigastric vein (SIEV) was anastomosed to a recipient vein to provide extra venous drainage. At the end of the operation an IR image was taken of the flap. In the postoperative period, flaps were monitored by clinical assessment (color, refill, turgor, temperature) and by arterial perforator sounds using the hand-held Doppler. In addition, DIRT was performed on all flaps on the first, third, and sixth postoperative days. During each examination, both breasts were uncovered and subjected to a 10-minute period of acclimatization at room temperature (22°–24°C). Thermographic image sequences were taken at the end of the acclimatization period and following a thermal challenge, similar to that used in the preoperative examination. A Nikon Laird S270 (Tokyo, Japan) IR camera and a FLIR (FLIR ThermaCAM S65 HS FLIR Systems, FLIR Systems AB, Boston, MA) IR camera were used for monitoring skin surface temperatures. Both cameras are capable of producing sequences of high-definition digital IR images. An accuracy of 0.1°C in measurements was obtained. IR thermal images were taken at regular intervals to register the rate and pattern of rewarming. All images were electronically stored and afterward processed using image analysis software PicWin-IRIS (EBS System Technik Gmbh, Munich, Germany) for the Nikon IR camera and ThermaCAM Researcher Pro 2.8 SR-1 (FLIR Systems AB) for the FLIR IR camera. At the end of the DIRT examination, the presence and location of arterial perforator sounds associated with hot spots seen in the IR images were confirmed with the hand-held Doppler. Clinical evaluation of the flap by color, turgor, capillary refill, and temperature was also recorded.
RESULTS Breast reconstruction with free DIEP flaps was carried out in 16 patients, mean age was 48 years (range 34 – 65 years), and a mean BMI was 25.8 kg/m2 (range 20.2–30.5 kg/m2). Seven DIEP flaps were perfused by 1 lateral perforator and 9 DIEP flaps were perfused by 2 lateral perforators. All DIEP flaps survived, with 2 patients having partial flap loss of approximately 5%. At a 3 months follow © 2008 Lippincott Williams & Wilkins
Perfusion Dynamics of Free DIEP and SIEA Flaps
up, 3 other patients had developed minor fat necrosis of maximal 3 ⫻ 3 cm, no surgical intervention was required. A mean of 76% (range 57%–98%) of the entire abdominal flap, with a mean weight of 989 g (range 505–1664 g), was used for reconstruction. The mean DIEP flap weight was 751 g (range 459 –1104 g). Breast reconstruction with a SIEA flap was carried out in 4 patients with a mean age of 50 years (range 38 –56 years) and mean BMI of 25.2 kg/m2 (range 23.7–28.7 kg/m2). A mean of 75% (range 51%– 93%) of the entire abdominal flap, with a mean weight of 798 g (range 461–1065 g), was used. The SIEA flaps had a mean weight of 571 g (range 431– 838 g). One flap did not survive and was lost on the third postoperative day. In 15 of the 16 DIEP flaps, and in 2 of the 4 SIEA flaps, signs of impaired venous drainage were observed intraoperatively. In these cases an additional venous anastomosis was performed. Analysis of DIRT image sequences of DIEP and SIEA flaps revealed individual variations in skin surface temperature. There was, however, a clear reproducibility in the rate and pattern of rewarming for both types of flaps. In all DIEP flaps rewarming started with the appearance of a hot spot that was positioned over the entrance point of the perforator in zone I. From here, the flap showed a general rewarming of zone I, followed by the adjacent lateral zone, and finally the zones across the midline. This pattern of rewarming of the DIEP flaps was seen on all 3 days. In addition to the general rewarming pattern, the flaps also showed a pattern of rewarming with hot spots. This pattern followed the same sequence of rewarming. Zone I was first rewarmed, then the adjacent ipsilateral zone and finally the contralateral side. However, while the general rewarming was already apparent at the end of the operation, the appearance of hot spots in all zones became evident over several days. At the end of the operation, hot spots were in most flaps confined to zone I. On day 1, hot spots were seen on the ipsilateral side in zone I as well as in the adjacent lateral zone (Fig. 1). On the contralateral side, hot spots first became clearly visible on days 3 and 6 (Fig. 2). There were, however, 3 DIEP flaps that showed some hot spots on the contralateral side near the midline as early as day 1 (Fig. 3). As all DIEP flaps, these flaps were based on lateral perforators. Two flaps developed partial flap loss on the contralateral side after a period with impaired perfusion clinically diagnosed as venous congestion in zone IV. These flaps also showed a pattern of rewarming with hot spots. The hot spots were finally seen on the contralateral side close to the area with necrosis (Fig. 4). The 3 successful SIEA flaps also showed a general rewarming pattern and a pattern of rewarming by hot spots. Both patterns started in the zone overlying the SIEA, followed by the adjacent medial zone and finally the zones across the midline. There was here also a difference in the time sequence. The general rewarming of all zones was already visible on the day of operation. In the pattern of rewarming by hot spots, the first hot spots were seen in the zone overlying the SIEA on the operation day, followed by the appearance of hot spots in the adjacent medial zone on day 1. No hot spots were seen in the flap area across the midline on day 1, however, they had appeared on day 3 and their number had increased on day 6. The one SIEA flap that failed showed no increase in the number of hot spots on day 3. In fact, their number and their rate of rewarming had decreased. Color Doppler flowmetry showed patency of both microvascular anastomosis and arteriovenous shunting near the entrance point of the pedicle into the flap. This was confirmed on day 3 during removal of the flap. The DIRT image sequences enabled us to make a qualitative statement on the rate of rewarming of the free DIEP and free SIEA flaps. On day 1 all flaps showed a higher skin surface temperature compared with the preoperative IR images of the donor area of the flaps. The rate of rewarming of the flaps after the cold challenge 43
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FIGURE 1. A, Photograph of a DIEP flap based on 2 lateral perforators identified with arterial Doppler sounds that are marked with 2 sutures (arrows). B–E, DIRT image sequence on day 1: B, precooling; C, end-cooling; D, rewarming starting in zone I. Note the hot spots at the suture locations. E, Increase of the number of hot spots visible in the adjacent ipsilateral zone.
FIGURE 2. Photographs and DIRT image sequences of a DIEP flap taken on days 1, 3, and 6. Although there is reduction in hyperemia from day 1 to day 6, the hot spots on the contralateral side become clearly visible on days 3 and 6. On day 1, they were barely visible even after 9 minutes of rewarming. B, precooling; C, end-cooling; D, taken after 60 seconds rewarming; E, taken after 180 seconds rewarming.
FIGURE 3. Photographs and DIRT image sequences of a DIEP flap taken on days 1 and 6. On day 1, hot spots are already visible on the contralateral side near the midline. Note the reduced hyperemia of the entire flap, especially in zone I while at the same time the number of hot spots across the midline increases.
was considerably higher compared with that of the preoperative donor areas. The state of hyperemia of the whole flap was most pronounced on day 1, and especially in zone I where the first hot spot was registered (Figs. 1–3). The hyperemia of the whole flap was registered both on the IR images and clinically. The arterial perforator sounds registered in zone I with the handheld Doppler were more powerful compared with the preoperative sounds heard in this zone. The temperature measured at the hot spot appeared to correlate with the volume intensity registered with the Doppler ultrasound. Even though hot spots were visible on IR images, there were cases where the handheld Doppler was not able to register an arterial perforator signal at the hot spot. In these cases, arterial Doppler sounds were first heard on the next examination day when the hot spot itself had become more visible. For all flaps, an increase in the rate of rewarming of hot 44
spots on the contralateral side was seen from day 3 to day 6. At the same time a decrease was seen in the rate of rewarming of hot spots on the ipsilateral side. This coincided with a decrease in hyperemia of the whole flap and of the ipsilateral hot spots as seen on the IR images. The DIRT image sequences from the 3 postoperative examination days in Figure 2 illustrate the reduced hyperemia of the flap, especially in zone I, and at the same time, the improved visibility of hot spots on the contralateral side.
DISCUSSION The aim of this study was to obtain more insight in the perfusion dynamics of free DIEP and free SIEA flaps. Both flaps are characterized by a well-defined entrance point of the vascular pedicle into the flap. Rapid rewarming of the flap after a thermal © 2008 Lippincott Williams & Wilkins
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FIGURE 4. Photograph and DIRT images of a DIEP flap in a patient who developed partial flap necrosis in zone IV. The photograph (A) was taken on day 24. The flap is based on a lateral perforator as illustrated in B, taken at the end of the operation. There is a progressive increase in the number of hot spots across the midline with time. Even though the hyperemia is reduced with time, new hot spots become visible in close proximity to the necrotic area. Images C–E were taken 120 seconds and F, 65 seconds following rewarming after fan cooling. cold challenge has to start at this entrance point. The dynamics of rewarming described by its rate and pattern are easily registered with an IR camera. Qualitative analysis of the pattern of rewarming of the DIEP flaps revealed that each pattern can be divided into 2 patterns; a general pattern of rewarming and a pattern of rewarming with hot spots. Rewarming started for both patterns in the zone positioned over the perforator (zone I), followed by the adjacent ipsilateral zone (zone II), and finally the zones across the midline (zone III and zone IV). This sequence of perfusion is identical to that found in intraoperative studies.14,17 Based on clinical observations Dinner et al31 had the same zone arrangement for the pedicled TRAM flap. Qualitative analysis of the rate of rewarming showed an initial hyperemia that subsided during the subsequent examination days. A plausible explanation for the rate and pattern of rewarming of the free DIEP flaps seen with DIRT is obtained by correlating the results from our study with those from others. The DIEP flap receives its blood supply from 1 or 2 direct perforators of the DIEA. Direct perforators are perforators with a diameter larger then 0.5 mm.11 El-Mrakby and Milner11 found in their anatomic study an average of 5.4 direct perforators (range 4 –7) arising from the DIEA to the lower transverse abdominal flap. These perforators have a straight course toward the subdermal level and keep a constant diameter throughout their course. At the level superficial to Scarpa’s fascia, they begin to divide into branches that contribute to the formation of the subdermal plexus of vessels. At the subdermal level the perforators finally divide into smaller branches. Some of these branches are directed upward to supply the skin, whereas others are directed downward to supply the subcutaneous fat. El-Mrakby and Milner32 also performed a histologic study, which showed that large direct perforators feed the subdermal plexus and supply the superficial fat, while small indirect perforators contribute to the formation of the deep subcutaneous vascular plexus at the deep fat level. These findings are in agreement with those of Taylor.11 Their cross-sectional radiographic study revealed a blood supply to the superficial subcutaneous layer caused by “raining down” from the subdermal plexus. The xerographic and computer tomographic study by Kaufman et al33 supports this finding. The stepwise progression seen in the general pattern of rewarming as registered on the IR images can be explained as a stepwise progression of perfusion in the subdermal plexus of the zones included in the flap (Fig. 5). The time sequence of rewarming of these zones indicates the existence of choke vessels in the subdermal plexus. © 2008 Lippincott Williams & Wilkins
As mentioned in the introduction, angiosomes throughout the body are usually interconnected to adjacent angiosomes at every tissue level by reduced-caliber choke vessels, but sometimes by true anastomoses.9 Boyd et al34 found that the major musculocutaneous perforators (⬎0.5 mm in diameter) of the DIEA form arterial network connections with perforators of their own system and with the SIEA system. The rapid increase in number of hot spots in zone I at the end of the operation indicates that the interconnections between the perforators of the DIEA are true anastomoses. The interconnections are located in the subcutaneous tissue between perforators directed toward the skin. These perforators transport heat to the skin surface, visible as hot spots on the IR images. Each hot spot correlates with the location at which arterial perforator sounds can be registered. The small vessels from the subdermal plexus are not capable of producing hot spots and Doppler sounds. The hot spots in the adjacent ipsilateral zone appeared later than in zone I and were first seen on day 1. The hot spots on the contralateral side were, for nearly all flaps, first seen on day 3. Dhar and Taylor10 reported on the anatomic changes that occur at the level of the reduced-caliber choke vessels between 2 adjacent ipsilateral vascular territories of a pedicled flap. The results from their study on the delay phenomenon in a rabbit model showed an initial vasoconstriction, which lasted for up to 3 hours. Between 3 and 24 hours, the choke vessels returned to a diameter comparable to the control and, thereafter, underwent progressive sequential dilation that was most dramatic between 48 and 72 hours. Aydin and Mavili35 investigated a similar model but used a flap with 3 vascular territories including the contralateral side. Based on laser Doppler flowmetry measurements they concluded that the reduced-caliber vessels at the midline behaved like true choke vessels, in contrast to the vessels interconnecting the 2 angiosomes on the ipsilateral side. Our study in the DIEP flap also indicates that the choke vessels at the midline form a greater resistance for circulation than the choke vessels between the ipsilateral angiosomes. This is true for the pattern of general rewarming and for the pattern of rewarming by hot spots. A qualitative analysis of the rate of rewarming was performed for both patterns of rewarming. The general pattern showed a high rate of rewarming of the whole flap on the day of operation and on day 1. This high rate of rewarming was associated with a hyperemia that was registered for the whole flap on the IR images and clinically. On days 3 and 6, the hyperemia subsided. During the 45
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FIGURE 5. Schematic illustrations of the blood vessels involved in skin surface rewarming patterns in a DIEP flap. A, The general rewarming pattern can be explained by the perfusion of the subdermal plexus via the selected direct perforator in zone 1. The hot spot indicates the location of the direct perforator on the IR image. B, The rewarming pattern with additional hot spots is explained by the perfusion of other direct perforators after interconnections with the selected direct perforator in zone I have opened. Choke vessels are located between zones in the subdermal plexus and subcutaneous layer. period of hyperemia, hot spots are initially confined to zone I. This indicates that the subdermal plexus of all zones are initially only perfused through the perforators in zone I (Fig. 5). Initially, hot spots were only seen on the ipsilateral side in zone I and showed a high rate of rewarming. During subsequent examination days, the ipsilateral hot spots showed a decrease in the rate of rewarming, while at the same time the newly appeared hot spots in the contralateral zones showed an increase in the rate of rewarming. It is interesting to note that even though the hyperemia subsides over time, the total number of hot spots increases. The hyperemia of the whole flap has been attributed to the denervation of the flap, which causes a relaxation of sympathetic tone in the vessel wall.22 In addition, Heitland et al12 measured a 2-fold increase in flow volume in the DIEP flap pedicle after anastomosis to the internal mammary vessels compared with the flow volume measured in the donor pedicle. This increase in flow volume was still evident 1 year later.12 We registered a decrease in hyperemia with time that coincided with an increase in the number of hot spots on the contralateral side. While the hot spots on the contralateral side become more visible on consecutive examination days, the rate of rewarming of hot spots on the ipsilateral side decreased. We suggest that a redistribution of blood within the whole flap takes place due to an increase in the diameter of choke vessel lumen in the subcutaneous tissue. As a result, the perfusion of the subcutaneous tissue improves, especially on the contralateral side. The results of this qualitative analysis of the rate of rewarming indicate that the choke vessels in the subdermal plexus behave differently from those in the subcutaneous tissue. During hyperemia the subdermal plexus of the whole flap is already well perfused. However, it takes several days before the subcutaneous tissue of the whole flap becomes well perfused. Homogenization of perfusion of the subdermal plexus of the DIEP flap preceded, therefore, the homogenization of the subcutaneous tissue. For the SIEA flap, DIRT also showed a general rewarming pattern and a pattern with the appearance of hot spots. The choke vessels between the ipsilateral angiosomes and those between the angiosomes at the midline appear to behave in a similar way to that seen in the DIEP flap. The sequence of perfusion of the zones was similar to that reported by others.14,17 In contrast to the DIEP flap, 2 choke vessel zones have to be passed to reach the contralateral side 46
of the SIEA flap, which could be an alternative explanation for the late appearance of hot spots in that area. This study shows that the perfusion of the free DIEP and SIEA flaps is a dynamic process with a stepwise progression during the first postoperative week. This stepwise progression takes place at 2 levels, the subdermal plexus and the subcutaneous tissue, each with its own time sequence. The perfusion in the subcutaneous tissue contributes through direct perforators to the perfusion of the subdermal plexus. As in the delay phenomenon, survival of free DIEP and SIEA flaps is closely linked to the behavior of the choke vessels that link adjacent vascular territories within the flap. The results from this study indicate that for the free DIEP and SIEA flap, choke vessels between the angiosomes on each side of the midline form a greater resistance for circulation than the choke vessels between the ipsilateral angiosomes. Hemi-DIEP and hemi-SIEA flaps can therefore be considered as very reliable.1 The perfusion of these flaps across the midline has been considered by others as random.14,36 However, the rewarming patterns from this study suggest that perfusion of the contralateral side takes place through a vascular network that is similar on both sides of the midline. Perfusion of the perforators on the contralateral side, visible by the appearance of hot spots, is most likely possible after a process of dilation at the choke vessel level in the subcutaneous tissue. Dhar and Taylor10 stated that the time sequence for delay appears to be similar in different species and in different tissues, suggesting the possibility of a universal process for delay. The results from our study suggest that the choke vessels at the subdermal level cause less resistance to circulation compared with those at the subcutaneous level. Adequate perfusion of the zones at the subdermal level of the free DIEP and SIEA flaps is therefore earlier reached than at the subcutaneous level. From earlier studies we know that the subdermal plexus contributes to the perfusion of the superficial subcutaneous layer.11,32 This might explain why skin and superficial subcutaneous fat may survive in the presence of fat necrosis in the deep subcutaneous layer. This deep layer only becomes adequately perfused after choke vessels in the subcutaneous layer have dilated. This might also explain why nearly the entire transverse abdominal flap can be safely used if this flap is thin.17,18 © 2008 Lippincott Williams & Wilkins
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It is concluded that perfusion of the free DIEP flap and the free SIEA flap during the first postoperative week is a dynamic process. There is a stepwise progression of perfusion that proceeds faster at the level of the subdermal plexus than at the subcutaneous layer. For both flap types, the choke vessels at the midline form a zone of larger resistance for circulation than the choke vessels between the ipsilateral zones.
ACKNOWLEDGMENTS The authors thank senior technician Knut Steinnes, Department of Medical Physiology and Rod Wolstenholme, Audio-Visual Department at the Faculty of Medicine, University of Tromsø, for technical assistance in preparation of the figures. REFERENCES 1. Chevray PM. Update on breast reconstruction using free TRAM, DIEP, and SIEA flaps. Sem Plast Surg. 2004;18:97–104. 2. Klebuc M, Spiegel A, Friedman J. Recent innovations in microsurgical breast reconstruction. Sem Plast Surg. 2003;17:39 – 47. 3. Granzow JW, Levine JL, Chiu ES, et al. Breast reconstruction with the deep inferior epigastric perforator flap: History and an update on current technique. J Plast Reconstr Aesth Surg. 2006;59:571–579. 4. Arnezˇ ZM, Khan U, Pogorelec D, et al. Rational selection of flaps from the abdomen in breast reconstruction to reduce donor site morbidity. B J Plast Surg. 1999;52:351–354. 5. Allen RJ, Heitland AS. Superficial inferior epigastric artery flap for breast reconstruction. Sem Plast Surg. 2002;16:35– 42. 6. Blondeel N, Vanderstraeten GG, Monstrey SJ, et al. The donor site morbidity of free DIEP flaps and free TRAM flaps for breast reconstruction. Br J Plast Surg. 1997;50:322–330. 7. Blondeel N, Boeckx WD, Vanderstraeten GG, et al. The fate of the oblique abdominal muscles after free TRAM flap surgery. Br J Plast Surg. 1997;50: 315–321. 8. Futter CM. Abdominal donor site morbidity: impact of the TRAM and DIEP flap on strength and function. Sem Plast Surg. 2002;16:119 –130. 9. Taylor GI, Palmer JH. The vascular territories (angiosomes) of the body: experimental study and clinical applications. Br J Plast Surg. 1987;40:113–141. 10. Dhar SC, Taylor GI. The delay phenomenon: the story unfolds. Plast Reconstr Surg. 1999;104:2079 –2091. 11. El-Mrakby HH, Milner RH. The vascular anatomy of the lower anterior abdominal wall: a microdissection study on the deep inferior epigastric vessels and the perforator branches. Plast Reconstr Surg. 2002;109:539 –543; discussion 544 –547. 12. Heitland AS, Markowicz M, Koellensperger E, et al. Duplex ultrasound imaging in free transverse rectus abdominis muscle, deep inferior epigastric artery perforator, and superior gluteal artery perforator flaps. Ann Plast Surg. 2005;55:117–121. 13. Kroll SS. Fat necrosis in free transverse rectus abdominis myocutaneous and deep inferior epigastric perforator flaps. Plast Reconstr Surg. 2000;106:576 – 583. 14. Holm C, Mayr M, Ho¨fter E, et al. Perfusion zones of the DIEP flap revisited: a clinical study. Plast Rconstr Surg. 2006;117:37– 43. 15. Granzow JW, Levine JL, Chiu ES, et al. Breast reconstruction using perforator flaps. J Surg Oncol. 2006;94:441– 454. 16. Arnezˇ ZM, Khan U, Pogorelec D, et al. Breast reconstruction using the free superficial inferior epigastric artery (SIEA) flap. Br J Plast Surg. 1999;52: 276 –279.
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Perfusion Dynamics of Free DIEP and SIEA Flaps
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