Mark V. Schaverien

The perforasome theory: vascular anatomy and clinical implications.

Background: A clear understanding of the vascular anatomy of an individual perforator relative to its vascular territory and flow characteristics is essential for both flap design and harvest. The authors investigated the three-dimensional and four-dimensional arterial vascular territory of a single perforator, termed a “perforasome,” in major clinically relevant areas of the body. Methods: A vascular anatomy study was performed using 40 fresh cadavers. A total of 217 flaps and arterial perforasomes were studied. Dissection of all perforators was performed under loupe magnification. Perforator flaps on the anterior trunk, posterior trunk, and extremities were studied. Flaps underwent both static (three-dimensional) and dynamic (four-dimensional) computed tomographic angiography to better assess vascular anatomy, flow characteristics, and the contribution of both the subdermal plexus and fascia to flap perfusion. Results: The perfusion and vascular territory of perforators is highly complex and variable. Each perforasome is linked with adjacent perforasomes by means of two main mechanisms that include both direct and indirect linking vessels. Vascular axis follows the axiality of linking vessels. Mass vascularity of a perforator found adjacent to an articulation is directed away from that same articulation, whereas perforators found at a midpoint between two articulations, or midpoint in the trunk, have a multidirectional flow distribution. Conclusions: Each perforator holds a unique vascular territory (perforasome). Perforator vascular supply is highly complex and follows some common guidelines. Direct and indirect linking vessels play a critical part in perforator flap perfusion, and every clinically significant perforator has the potential to become either a pedicle or free perforator flap.

Arterial and venous anatomies of the deep inferior epigastric perforator and superficial inferior epigastric artery flaps.

Background: This study uses three- and four-dimensional computed tomographic angiography and venography to evaluate the microvascular anatomy and perfusion of the deep inferior epigastric artery perforator (DIEP) and superficial inferior epigastric artery (SIEA) flaps. Methods: Ten DIEP flaps harvested from fresh cadavers and two abdominoplasty specimens were used. Studies of the largest single perforators from the medial and lateral rows were performed. Injections of the vena comitans of the perforators and of the superficial inferior epigastric veins were performed to evaluate venous drainage. Results: Zone IV was not perfused following injection of a lateral row perforator, whereas injection of a medial row perforator consistently resulted in perfusion of zone IV. Image analysis revealed the presence of large-diameter linking vessels at the level of the subdermal plexus between the perforators of the medial row, whereas lateral row perforators predominantly perfused the lateral aspect of the flap and perfused the medial row perforators by means of recurrent flow through the subdermal plexus. Medial row perforators perfused the flap in a central elliptical pattern, whereas lateral row perforators predominantly perfused the ipsilateral portion of the flap. The SIEA vessel branches were seen to course to the subdermal plexus and then to perfuse ipsilateral perforators through the subdermal plexus. Venous drainage occurred by means of the superficial inferior epigastric veins and the venae comitantes of the perforators. Conclusions: This study demonstrates that flow through medial and lateral row perforators occurs in physiologically stereotyped patterns. A medial row perforator should be selected if zone IV perfusion is required. The SIEA was consistently seen to only perfuse a hemiflap.

Perforators of the lower leg: Analysis of perforator locations and clinical application for pedicled perforator flaps

Background: Pedicled perforator flaps in the lower leg enable reconstruction of a variety of local defects without microvascular anastomoses and with minimal donor-site morbidity. This study determined the reliable locations of the lower leg perforators. Methods: Twenty lower limbs harvested from fresh cadavers were used. In 15 specimens, colored latex intra-arterial injections were performed followed by dissection in the suprafascial plane; perforators with a diameter greater than 0.5 mm were located with respect to a line between the tips of the medial and lateral malleoli. In five further specimens, intra-arterial injection of a barium sulfate/gelatin mixture was performed and computed tomographic scans were acquired. Cluster analysis was performed to determine the 5-cm intervals where perforators were most commonly encountered within each septum. Results: Perforators were located in discrete intermuscular septa. Those arising from the anterior tibial artery were predominantly encountered within three septa, and those of the peroneal and posterior tibial arteries were found within discrete septa. Reliable perforators were found within three distinct 5-cm intervals: at 4 to 9 cm, 13 to 18 cm, and 21 to 26 cm from the intermalleolar line. The anterior tibial artery perforators clustered in the distal and proximal intervals, those of the peroneal artery in the middle interval, and those of the posterior tibial artery in all three intervals. Conclusions: Reliable perforators from the anterior tibial, posterior tibial, and peroneal arteries can be found in distinct 5-cm intervals within intermuscular septa. This may aid in the design of pedicled perforator flaps of the lower leg.

Three- and four-dimensional computed tomographic angiography and venography for the investigation of the vascular anatomy and perfusion of perforator flaps.

Background: Two-dimensional contrast radiography is the current standard for investigating the vascular anatomy of surgical flaps. The microvascular anatomy of the perforator flap, however, is limited conceptually by representation in two dimensions. Static three-dimensional computed tomographic angiography enables vascular anatomy to be evaluated in the coronal, axial, and sagittal planes, and dynamic four-dimensional computed tomographic angiography allows the vascular filling of a perforator flap to be visualized over short time intervals in three dimensions. Methods: An anatomical study was performed using 11 fresh adult cadavers acquired through the Willed Body Program at the University of Texas Southwestern Medical Center, in Dallas, Texas. Four male and seven female cadavers were included in the study. Perforator flaps harvested included the following: anterolateral thigh, deep inferior epigastric perforator, superior gluteal artery perforator, inferior gluteal artery perforator, thoracodorsal artery perforator, anteromedial thigh, and dorsal intercostal artery perforator. Conclusions: Novel techniques for acquiring both static and dynamic three-dimensional images of macrovascular and microvascular perforator flap anatomy using computed tomographic angiography have been described. This methodology has also allowed the sequential investigation of adjacent vascular territories. This can provide a better understanding of how perforator flaps and the skin are perfused and may aid in the future design of new flaps.

Perforator flaps: History, controversies, physiology, anatomy, and use in reconstruction

Learning Objectives: After studying this article, the participant should be able to: 1. Understand the history and controversies surrounding perforator flaps. 2. Describe the anatomy and understand the theories surrounding the physiology of perforator flaps. 3. Understand the uses of perforator flaps in reconstruction. 4. Understand the future directions of the perforator flap concept. Summary: Perforator flaps have the advantages of reduced donor-site morbidity, versatility to accurately replace the components required at the recipient site, a longer pedicle than is achievable with the parent musculocutaneous flap, and freedom from orientation of the pedicle. Their development has followed our understanding of the blood supply from a source artery to the skin, which has been achieved because of landmark studies by Manchot, Salmon, Milton, Taylor, and others. Many articles now attest to the safety and reliability of perforator flaps. This review aims to outline the history and controversies surrounding perforator flaps and to describe the anatomy of the “workhorse” perforator flaps and their use in microsurgical reconstruction. These flaps include the deep inferior epigastric artery, the anterolateral thigh, the thoracodorsal artery, and the superior and inferior gluteal artery perforator flaps.

Three- and four-dimensional computed tomographic angiography and venography of the anterolateral thigh perforator flap

Background: This study presents a detailed three- and four-dimensional appraisal of the arterial and venous anatomy and perfusion of the anterolateral thigh flap using a novel computed tomographic technique. Methods: Eighteen anterolateral thigh flaps harvested from fresh Western cadavers were used. Four-dimensional computed tomographic angiography with injection of iodinated contrast medium into isolated perforators and their venae comitantes was used to investigate the arterial and venous anatomy and flap perfusion. Additional perforators were injected to investigate the vascular connections within the flap. Changes in flap perfusion after thinning and adipofascial flap harvest were also examined, and contrast density within each flap plexus with respect to the perforator was examined. Results: Large-diameter linking vessels at the suprafascial level enabled perfusion of adjacent vascular territories and of the subdermal plexus between angiotomes. Thinning reduced the size of the vascular territory by ligating recurrent vessels at the level of the suprafascial plexus. Adipofascial flap harvest prevented perfusion of the recurrent vessels, demonstrating the role of the subdermal plexus in recurrent flow. Three distinct perforator complex patterns were found with relevance to flap thinning. A superficial venous system perfused the venae comitantes of the descending branch of the lateral femoral circumflex artery and the long saphenous vein. Conclusions: A reduction in vascular territory occurs in the anterolateral thigh flap after thinning and is attributable to ligation of vessels within the suprafascial plexus. Recurrent flow through the subdermal plexus was seen dynamically for the first time and appears to be an important mechanism for skin perfusion.

The Paramedian Forehead Flap : A Dynamic Anatomical Vascular Study Verifying Safety and Clinical Implications

Background: Nasal reconstruction with use of the forehead flap has been performed for hundreds of years. Forehead vasculature has been studied; however, anatomical relationships to the forehead flap have not been adequately examined. This anatomical study evaluated the vascular anatomy of the paramedian forehead flap. Methods: Five fresh cadaver heads were used. Four underwent cannulation of internal and external carotids bilaterally followed by injection of a barium sulfate/gelatin mixture and three-dimensional computed tomographic angiography to evaluate vascular anatomy. In one specimen, the supraorbital, supratrochlear, and angular arteries were cannulated. Methylene blue dye was injected to identify vascular territory followed by injection of contrast media for dynamic four-dimensional computed tomographic angiography. A paramedian forehead flap was raised and the injections were repeated. Colored-latex was injected followed by dissection. Measurements were made on a computed tomography workstation. Results: A periorbital plexus extends to 7 mm over the orbital rim. The angular, supratrochlear, and supraorbital arteries communicated into the flap by means of the vascular plexus. The supratrochlear vessel ran axially into the forehead flap and continued across the transverse limb of the flap. The deep branch of the supratrochlear ascended the periosteum under the flap. Noncontiguous vessels were noted to back-fill with latex through the subdermal plexus in the distal flap. Conclusions: Maximal three-vessel flow may be obtained by preserving periosteum at least 3 cm over the orbital rim and beginning the flap 7 mm above the orbital rim. The subdermal plexus of the forehead is robust, enabling preservation of the distal transverse limb of the forehead flap.

The Extended Anterolateral Thigh Flap: Anatomical Basis and Clinical Experience

Background: Reports suggest that the anterolateral thigh flap can be reliably extended to include adjacent vascular territories. The vascular basis of this phenomenon is poorly understood. This study examines the three- and four-dimensional arterial and venous anatomy of the extended anterolateral thigh flap and reports the results of a clinical series of extended anterolateral thigh flaps. Methods: Fifteen anterior hemithigh specimens harvested from fresh cadavers from the Western population were studied. Four-dimensional computed tomographic angiography was used to investigate the arterial and venous anatomy and pattern of perfusion. Injection of perforators within the lateral femoral circumflex femoral vascular territory, and those of the common femoral and superficial femoral arteries, was performed to investigate the vascular connections within the extended anterolateral thigh flap. Static three-dimensional imaging and latex dissections were also performed to confirm the results. A clinical series of 12 consecutive patients is also reported in which extended anterolateral thigh flaps were used for posttrauma or postoncologic reconstruction. Results: Large-diameter linking vessels at the suprafascial level enabled perfusion of the adjacent common femoral and superficial femoral artery vascular territories. In the clinical series, the flap cutaneous territory ranged from 250 to 630 cm2 (mean, 365 cm2), with all flaps except one perfused by a single perforator. No partial or complete flap losses occurred. Conclusions: This study reports the vascular basis and clinical safety of the extended anterolateral thigh flap, which can be harvested if the linking vessels between adjacent vascular territories in the anterior thigh are preserved. The extended flap is reliably perfused by a single dominant perforator.

Lower limb reconstruction using the islanded posterior tibial artery perforator flap.

Background: The islanded propeller-design posterior tibial artery perforator flap is a versatile local reconstructive option for defects of the lower leg, ankle, heel, and foot. Methods: A retrospective review of patients undergoing this procedure from 1989 to 2009 was performed. Case note analysis was performed to determine demographic and perioperative factors, and complications and outcomes. Results: One-hundred six flaps were islanded on a single perforator from the posterior tibial artery in 100 patients (six bilateral). Seventy-two percent of defects were at the lower third of the leg, and 10 percent were at the ankle, heel, or foot. The median angle of rotation about the perforator was 160 degrees (range, 60 to 180 degrees). Eighty-eight percent of flaps had associated fractures, 60 percent were managed using intramedullary nailing, and 44 percent were Gustilo grade IIIb fractures. Five percent of patients subsequently developed osteomyelitis, and the primary nonunion rate was 9 percent. There was an 8.5 percent complete and 12 percent partial flap failure rate, both associated with cigarette smoking, diabetes, and peripheral vascular disease. Limb salvage for complete flap failures included free muscle flap transfer in six cases and below-knee amputation in three cases. Conclusion: The islanded propeller-design posterior tibial artery perforator flap provides reliable coverage of lower limb defects, particularly of the lower third.

The pedicled descending branch muscle-sparing latissimus dorsi flap for breast reconstruction.

Background: The pedicled descending branch muscle-sparing latissimus dorsi flap with a transversely oriented skin paddle presents distinct advantages in breast reconstruction, including reduced donor-site morbidity and greater freedom of orientation of the skin paddle. This study reports the anatomical basis, surgical technique, complications, and aesthetic and functional outcomes following use of this flap for breast reconstruction. Methods: A retrospective study of 20 patients who underwent breast reconstruction with a pedicled muscle-sparing latissimus dorsi musculocutaneous flap was conducted. Indications for surgery included breast reconstruction following mastectomy, lumpectomy, and irradiation, and for correction of implant-related complications. Case-note review was performed, as was a functional evaluation consisting of a patient questionnaire, a Disabilities of the Arm, Shoulder, and Hand form, postoperative range-of-motion analysis, and instrumented strength testing comparing the operated and nonoperated sides. Aesthetic evaluation of the donor site was conducted by all patients. An anatomical study of 15 flaps harvested from fresh cadavers was performed to determine the location of the bifurcation of the thoracodorsal artery and the course of its descending branch. Results: Twenty-four descending branch muscle-sparing latissimus dorsi flaps were harvested. All donor sites were closed primarily, with skin paddle sizes ranging up to 25 × 12 cm. There was one case of minor flap tip necrosis and no instances of seroma. There was no statistically significant difference in strength or range of motion of the shoulder joint when comparing the operated to the nonoperated side. Two patients reported minor functional impact following surgery. Conclusions: The pedicled descending branch muscle-sparing latissimus dorsi flap with a transversely orientated skin paddle results in minimal functional deficit of the donor site, absence of seroma, large freedom of orientation of the skin paddle, low rate of flap complications, and a cosmetically acceptable scar.