Exclusive expression of KANK4 promotes myofibroblast mobility in keloid tissues.

Keloids are characterized by abnormal wound healing with excessive accumulation of extracellular matrix. Myofibroblasts are the primary contributor to extracellular matrix secretion, playing an essential role in the wound healing process. However, the differences between myofibroblasts involved in keloid formation and normal wound healing remain unclear. To identify the specific characteristics of keloid myofibroblasts, we initially assessed the expression levels of well-established myofibroblast markers, α-smooth muscle actin (α-SMA) and transgelin (TAGLN), in scar and keloid tissues (n = 63 and 51, respectively). Although myofibroblasts were present in significant quantities in keloids and immature scars, they were absent in mature scars. Next, we conducted RNA sequencing using myofibroblast-rich areas from keloids and immature scars to investigate the difference in RNA expression profiles among myofibroblasts. Among significantly upregulated 112 genes, KN motif and ankyrin repeat domains 4 (KANK4) was identified as a specifically upregulated gene in keloids. Immunohistochemical analysis showed that KANK4 protein was expressed in myofibroblasts in keloid tissues; however, it was not expressed in any myofibroblasts in immature scar tissues. Overexpression of KANK4 enhanced cell mobility in keloid myofibroblasts. Our results suggest that the KANK4-mediated increase in myofibroblast mobility contributes to keloid pathogenesis.

Peptide Receptor Radionuclide Therapy for Recurrent Olfactory Neuroblastoma After Cranioplasty for Surgical Infection: A Case Report.

BACKGROUND: Peputide receptor radionuclide therapy with 177Lu for midgut neuroendocrine metastasis has been clinically approved as a safe treatment. Unresectable metastases of olfactory neuroblastoma have shorter survival due to insufficient effective systemic treatment. CASE REPORT: Herein, we report a patient treated with peputide receptor radionuclide therapy for unresectable recurrent olfactory neusroblastoma following a rare cranial metastasectomy infection. A 50-year-old female patient with olfactory neuroblastoma of Kadish C was initially treated by skull base surgery plus postoperative radiotherapy following chemotherapy. Recurrent disease with neck and intracranial metastases was treated by four salvage surgeries. Surgical site infection following intracranial metastasectomy was treated with debridement and delayed cranioplasty. Peputide receptor radionuclide therapy was performed for unresectable multiple metastases after cranioplasty. Successful therapy using four cycles of peputide receptor radionuclide had neither grade 3 nor grade 4 adverse events. The patient was followed at an outpatient clinic. CONCLUSION: Further case accrual of peputide receptor radionuclide therapy is required to develop a treatment for unresectable olfactory neuroblastoma.

Creating and Transferring an Innervated, Vascularized Muscle Flap Made from an Elastic, Cellularized Tissue Construct Developed In Situ.

Reanimating facial structures following paralysis and muscle loss is a surgical objective that would benefit from improved options for harvesting appropriately sized muscle flaps. The objective of this study is to apply electrohydrodynamic processing to generate a cellularized, elastic, biocomposite scaffold that could develop and mature as muscle in a prepared donor site in vivo, and then be transferred as a thin muscle flap with a vascular and neural pedicle. First, an effective extracellular matrix (ECM) gel type is selected for the biocomposite scaffold from three types of ECM combined with poly(ester urethane)urea microfibers and evaluated in rat abdominal wall defects. Next, two types of precursor cells (muscle-derived and adipose-derived) are compared in constructs placed in rat hind limb defects for muscle regeneration capacity. Finally, with a construct made from dermal ECM and muscle-derived stem cells, protoflaps are implanted in one hindlimb for development and then microsurgically transferred as a free flap to the contralateral limb where stimulated muscle function is confirmed. This construct generation and in vivo incubation procedure may allow the generation of small-scale muscle flaps appropriate for transfer to the face, offering a new strategy for facial reanimation.

＜Editors' Choice＞ Long-term outcomes of lateral skull base reconstruction with a free omental flap and facial nerve reconstruction.

In lateral skull base reconstruction, it is necessary to seal the defect in the lateral skull base, fill the dead space, and, sometimes, reconstruct the facial nerve. However, this procedure is difficult to perform with a standard musculocutaneous flap. Therefore, for such cases, an omental flap is used in our hospital because of its flexibility. In this study, we report our experience with the procedure (lateral skull base reconstruction with a free omental flap) and its long-term outcome and facial nerve reconstruction, with special focus on facial nerve recovery. This study is a technical note and a retrospective review. It was conducted in Nagoya University Hospital. Overall, 16 patients (12 women and 4 men; mean age: 55.1 years) underwent lateral skull base reconstruction with a free omental flap after subtotal temporal bone resection or lateral temporal bone resection during 2005-2017. The main outcome measures were postoperative complications and facial nerve recovery: Yanagihara score and House-Brackmann grading system. Complications included partial necrosis and minor cerebrospinal fluid leakage in 2 patients. Facial nerve recovery could be observed more than 12 months after surgery, with a mean Yanagihara score of 19.6 and House-Brackmann grade of 3.60. The free omental flap is a reliable method for lateral skull base reconstruction, especially in cases where facial nerve reconstruction is needed. To the best of our knowledge, this is the first report on facial nerve recovery after lateral skull base reconstruction.

Artificial PGA/Collagen-based Bilayer Conduit in Short Gap Interposition Setting Provides Comparable Regenerative Potential to Direct Suture.

The aim of this study was to evaluate whether the Nerbridge, an artificial polyglycolic acid conduit with collagen matrix, is comparable to direct nerve suture in a rat sciatic nerve injury model in a short-gap interposition (SGI) setting. Methods: Sixty-six female Lewis rats were randomly divided into the sham group (n = 13); no reconstruction (no-recon) group (n = 13; rat model with 10 mm sciatic nerve defect); direct group (n = 20; rat sciatic nerve injury directly connected by 10-0 Nylon); and SGI group (n = 20; sciatic nerve injury repaired using 5-mm Nerbridge). Motor function and histological recovery were evaluated. The sciatic nerve and gastrocnemius muscle were harvested for quantification of the degree of nerve regeneration and muscle atrophy. Results: The SGI and direct groups achieved equal recovery in both functional and histological outcomes. At weeks 3 and 8 postsurgery, there was a significant improvement in the sciatic functional index of the SGI group when compared with that of the no-recon group (P < 0.05). Furthermore, the direct and SGI groups had less muscle atrophy at 4 and 8 weeks postsurgery compared with the no-recon group (P < 0.05). The axon density and diameter at the distal site in the SGI group were significantly higher than that in the no-recon group and comparable to that in the direct and sham groups. Conclusion: An artificial nerve conduit has equal potential as direct suture in motor nerve reconstruction when used in the SGI setting.

Hypothyroidism After Using Superior Thyroid Artery as A Recipient Artery.

OBJECTIVE: Superior thyroid artery (SThA) is a common recipient artery in free tissue transfer even after total pharyngolaryngoesophagectomy (TPLE) with hemithyroidectomy. The aim of this study was to evaluate whether the use of SThA as a recipient vessel affect thyroid function in patients undergoing TPLE with hemithyroidectomy. METHODS: From 2011 to 2020, 91 patients who underwent free jejunum transfer after TPLE with hemithyroidectomy were divided into two groups. In Group1 (n = 47), the contralateral SThA was used for the anastomosis. In Group2 (n = 44), other vessels were used. Retrospective chart review was performed comparing postoperative thyroid function between two groups. RESULTS: In group1, 17 patients presented hypothyroidism, 21 presented latent hypothyroidism and 9 presented no thyroid dysfunction comparing 15, 19, and 10 respectively in group 2. There were no significant differences between the two groups. CONCLUSION: Even after hemithyroidectomy, with inferior thyroid arteries are preserved, the SThA can be used as a recipient vessel. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:557-561, 2023.

Upper thoracic empyema and concomitant superior vena cava syndrome treated with reconstructive surgery using a pedicled omental flap.

Superior vena cava (SVC) syndrome refers to a constellation of symptoms secondary to obstruction of blood flow through the SVC. In this condition, venous blood that usually drains into the SVC is diverted into the inferior vena cava (IVC) via collateral veins. Reconstructive surgery is challenging in such cases owing to the anomalous venous system. In this case report, we describe reconstructive surgery using a pedicled omental flap in a patient with upper thoracic empyema and concomitant SVC syndrome. A 68-year-old man underwent resection of malignant thymoma, the bilateral brachiocephalic veins, and a part of the right upper lobe, followed by polytetrafluoroethylene (PTFE) graft placement for venous system reconstruction, 2 years prior to presentation. He developed postoperative upper thoracic cavity empyema, which necessitated PTFE graft removal. Although the infection was controlled after 2 months, multiple right upper lobe pulmonary fistulas persisted, and the patient was referred to our department for further evaluation. Contrast-enhanced computed tomography revealed SVC syndrome characterized by SVC obstruction and consequent drainage of venous blood from the upper trunk into the IVC via collateral vessels. We debrided necrotic and infected tissues, and a pedicled omental flap was placed for upper lobe fistula coverage. The patient showed an uncomplicated postoperative course, and no recurrent empyema or pulmonary fistulas were observed 3 years postoperatively. Flaps associated with the SVC system show high venous pressures. The use of a pedicled omental flap was deemed feasible because this graft reaches the upper thorax even though it is associated with the IVC system.

Effect of Incision Negative Pressure Wound Therapy on Donor Site Morbidity in Breast Reconstruction with Deep Inferior Epigastric Artery Perforator Flap.

Background: The usefulness of closed incision negative pressure wound therapy (ciNPWT) has been well documented in many surgical sites, except for the donor site of the deep inferior epigastric artery perforator (DIEP) flap. The aim of this study was to evaluate the effect of ciNPWT on microsurgical breast reconstruction using a DIEP flap. Methods: Fifty-six cases of breast reconstruction with DIEP flap were included and divided into two groups based on post-surgical wound management: the ciNPWT group received ciNPWT at the donor site, while the conventional group received conventional wound management. The primary outcomes were the incidence of seroma, wound dehiscence, and surgical site infection, and secondary outcomes were the time to drain removal and amount of drainage. The breast reconstruction risk assessment (BRA) score was used to evaluate the comprehensive risk in each case. Results: Among the patient and surgical characteristics, only the BRA score (P=0.02) and the time to elevate the flap (P=0.02) were significantly higher and longer in the ciNPWT group, respectively. The incidence of seroma, dehiscence, and wound infection showed no significant difference between the two groups. In the subgroup analysis of patients with body mass index ≥ 25, the primary outcomes did not differ, while the secondary outcomes were significantly lower in the ciNPWT group (drainage volume, P = 0.04; time to drain removal, P = 0.04). Conclusion: ciNPWT can potentially reduce the incidence of donor site complications of DIEP flaps, especially if the comprehensive risk for post-surgical complications is considered.

Colon cancer with extensive invasion of the abdominal wall treated with neoadjuvant chemotherapy and a free anterolateral thigh flap.

BACKGROUND: The treatment of locally advanced colon cancer is challenging, particularly when there is invasion of the abdominal wall. In such cases, balancing the securing of margins and sufficiently repairing abdominal wall defects is important, but difficult when the extent of invasion is large. CASE PRESENTATION: A 34-year-old male was referred to our hospital with abdominal pain and diagnosed with obstructive transverse colon cancer. He had undergone ileo-sigmoid colostomy at his previous hospital. The tumor was massive and invaded the abdominal wall (maximum diameter: approximately 12 cm), and was accompanied by regional lymph node swelling. No distant metastasis was detected. We diagnosed the tumor as cT4bN2bM0 Stage IIIC locally advanced transverse colon cancer and planned neoadjuvant chemotherapy. After two courses of FOLFOXIRI (5-fluorouracil, leucovorin, oxaliplatin, and irinotecan), he developed an entero-cutaneous fistula due to tumor penetration and required emergency diverting ileostomy construction. After the procedure, contrast-enhanced computed tomography showed good tumor shrinkage. As a result, the planned chemotherapy was canceled and he underwent radical resection of the tumor. En bloc extended right hemicolectomy was performed with excision of the fistula, ensuring a sufficient margin. The post-excision defect at the anterior abdominal wall involved 11 × 16 cm of fascia and 6 × 9 cm of skin located in the middle of the abdomen. A free anterolateral thigh flap was harvested from the right thigh and vascular pedicle was anastomosed to the right gastroepiploic artery and vein. The fascia lata, which was included in the anterolateral thigh flap, was sutured onto the abdominal wall fascia as inlay fashion to reconstruct the abdominal wall defect. Histopathology revealed moderately differentiated adenocarcinoma of the colon with no tumor cells in the abdominal wall tissue [post-chemotherapeutic state, therapy effect: Grade 1b; Stage IIA (ypT3N0M0)]. All resected margins of the specimen were free from adenocarcinoma. He was discharged on postoperative day 16. CONCLUSION: We report a case of colon cancer extensively invading the abdominal wall, which was completely resected. The abdominal wall defect was reconstructed with a free anterolateral thigh flap after tumor shrinkage with neoadjuvant chemotherapy. We present an efficient strategy for managing locally advanced colon cancer with extensive abdominal wall invasion.

Development of a Novel Scar Screening System with Machine Learning.

BACKGROUND: Hypertrophic scars and keloids tend to cause serious functional and cosmetic impediments to patients. As these scars are not life threatening, many patients do not seek proper treatment. Thus, educating physicians and patients regarding these scars is important. The authors aimed to develop an algorithm for a scar screening system and compare the accuracy of the system with that of physicians. This algorithm was designed to involve health care providers and patients. METHODS: Digital images were obtained from Google Images (Google LLC, Mountain View, Calif.), open access repositories, and patients in the authors' hospital. After preprocessing, 3768 images were uploaded to the Google Cloud AutoML Vision platform and labeled with one of the four diagnoses: immature scars, mature scars, hypertrophic scars, and keloid. A consensus label for each image was compared with the label provided by physicians. RESULTS: For all diagnoses, the average precision (positive predictive value) of the algorithm was 80.7 percent, the average recall (sensitivity) was 71 percent, and the area under the curve was 0.846. The algorithm afforded 77 correct diagnoses with an accuracy of 77 percent. Conversely, the average physician accuracy was 68.7 percent. The Cohen kappa coefficient of the algorithm was 0.69, while that of the physicians was 0.59. CONCLUSIONS: The authors developed a computer vision algorithm that can diagnose four scar types using automated machine learning. Future iterations of this algorithm, with more comprehensive accuracy, can be embedded in telehealth and digital imaging platforms used by patients and primary doctors. The scar screening system with machine learning may be a valuable support tool for physicians and patients. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.

Peripheral Nerve Regeneration Using Different Germ Layer-Derived Adult Stem Cells in the Past Decade.

Peripheral nerve injuries (PNIs) are some of the most common types of traumatic lesions affecting the nervous system. Although the peripheral nervous system has a higher regenerative ability than the central nervous system, delayed treatment is associated with disturbances in both distal sensory and functional abilities. Over the past decades, adult stem cell-based therapies for peripheral nerve injuries have drawn attention from researchers. This is because various stem cells can promote regeneration after peripheral nerve injuries by differentiating into neural-line cells, secreting various neurotrophic factors, and regulating the activity of in situ Schwann cells (SCs). This article reviewed research from the past 10 years on the role of stem cells in the repair of PNIs. We concluded that adult stem cell-based therapies promote the regeneration of PNI in various ways.

A Novel Technique to Lengthen the Reverse Latissimus Dorsi Muscle Flap Arc.

Reconstruction of the lower lumbar region is challenging for surgeons due to limited locoregional flap choices. The latissimus dorsi muscle flap is a mainstay for this area; however, there are several limitations, including that the dominant thoracodorsal artery and vein pedicle-based flaps are not reachable for reconstruction of the lumbar region, while perforator of intercostal artery and veins pedicle-based reverse latissimus dorsi (RLD) flap mobility is limited by including multiple perforators. Here, we describe a novel operative technique that lengthens the rotation arc of RLD muscle flaps. The surgical technique is as follows: RLD is elevated based on lower perforator of intercostal artery and veins (usually including two of the eighth-11th perforators); thoracodorsal artery and vein are ligated; and the flap is mobilized toward the defect. When RLD was not reachable to the defect, the far aspect of the intercostal artery and vein from the defect was ligated and the perforator was elevated with the near aspect of the intercostal artery and vein from intercostal space. Because the intercostal space measured between approximately 3 cm and 4 cm, this dissection gained 3-4 cm of rotational arc per intercostal space. Moreover, because the lower ribs follow a medio-cranial to latero-caudal direction, this dissection enabled the flap to extend latero-caudally or medio-cranially while maintaining its blood supply. Other applications using this technique may involve expanding the RLD flap arc caudally, ventrally, and ipsilaterally. We believe this new technique provides a reliable alternative for lower back reconstruction.

Skull Base Invasion Patterns of Malignant Head and Neck Tumors: A Neurosurgical Perspective.

Objective Craniofacial resection (CFR) and temporal bone resection (TBR) on malignant head and neck tumors (MHNTs) invading skull base require accurate and precise determination of the tumor invasion. We investigated tumor skull base invasion patterns and surgical results in CFR and TBR cases. Methods We performed either CFR or TBR for 75 selected patients with the possibility of en bloc resection over the period between 2011 and 2018. The medical charts of the selected patients were reviewed. Results Primary tumor onset site (TOS) groups were: (1) nasal cavity/ethmoid sinus, 20 cases; (2) orbit, 10 cases; (3) maxillary sinus, 28 cases; and (4) external ear/temporomandibular joint, 17 cases. Grades for tumor invasion depth (TID) included: (I) extracranial invasion and skull base bone invasion; (II) extradural invasion; or (III) intradural invasion. Patients in groups 1 and 2 had a significantly higher frequency of grade II and III invasions than patients in groups 3 and 4. The main invasion site was nasal cavity superior wall and ethmoid sinus superior wall for group 1 tumors, orbit superior wall, and lateral skull base sphenoid bone for group 2 and 3 tumors, and lateral skull base temporal bone for group 4 tumors. Positive resection margins represented a significant negative prognostic factor. TID and TOS did not affect skull base margin status. Conclusion Skull base invasion of MHNTs exhibits certain fixed patterns in sites susceptible to invasion based on the TOS. The frequencies of extradural and intradural invasions differed, indicating the importance for accurate preoperative tumor evaluation.

Surgical Classification of Radical Temporal Bone Resection and Transcranial Tympanotomy: A Retrospective Study from the Neurosurgical Perspective.

OBJECTIVE: To review the authors' surgical experience with radical temporal bone resection (TBR) with an emphasis on the classification of skull base osteotomy and transcranial tympanotomy (TCT) that is required for middle ear transection. METHODS: We reviewed the records of 25 patients who underwent radical TBR at our facilities between 2011 and 2020. RESULTS: The osteotomy line of radical TBR was divided into 3 segments: anterior (A), medial (M), and posterior (P). Each segment was further classified as follows: A1, through the glenoid fossa (1 patient); A2, in front of the glenoid fossa (23 patients); A3, through the greater wing of the sphenoid bone (1 patient); M1, through the middle ear (16 patients); M2, through the inner ear (9 patients); P1, through the mastoid (9 patients); and P2, through the posterior cranial fossa (16 patients). The M segment was significantly associated with operation time and intraoperative blood loss. In all patients with M1 osteotomy, TCT was performed; TCT was classified into superior and far posterior approaches. A superior approach was performed in all 16 patients, whereas the far posterior approach was performed in only 7 patients with both M1 and P2 osteotomy. CONCLUSIONS: Our newly proposed osteotomy classification of radical TBR is suitable for minute but clinically important adjustment of the osteotomy line. TCT is an indispensable technique for M1 osteotomy; our newly proposed classification expands our understanding of TCT and how to incorporate this technique into radical TBR.

Biological characterization of adipose-derived regenerative cells used for the treatment of stress urinary incontinence.

OBJECTIVE: To assess the characteristics of adipose-derived regenerative cells, and provide supportive data explaining the mechanism of efficacy observed for the use of these cells in the treatment of stress urinary incontinence. METHODS: Adipose tissues were harvested by abdominal liposuction from healthy donors and patients with stress urinary incontinence. Adipose-derived regenerative cells were isolated from tissues using the Celution system, and assessed for their characteristics and ability to differentiate into smooth muscle cells. RESULTS: Adipose-derived regenerative cells isolated by the Celution system developed into fibroblastic colonies. Flow cytometric analysis of adipose-derived stem cell markers showed that adipose-derived regenerative cells were positive for CD34 and CD44, and negative for CD31. Immunofluorescence staining after differentiation showed that colony-forming cells were positive for alpha-smooth muscle actin, calponin and desmin, which are smooth muscle cell markers. A cytokine release assay showed that adherent cells secreted cytokines associated with angiogenesis, including vascular endothelial growth factor-A, angiopoietin-2 and placental growth factor. CONCLUSIONS: Adipose-derived regenerative cells collected by the Celution system might have clonogenic capacity and an angiogenetic function. These properties might contribute to the mechanisms through which regenerative cell therapy by periurethral injection of autologous adipose-derived regenerative cells ameliorates stress urinary incontinence.

Prospective Evaluation of Health-Related Quality of Life in Patients Undergoing Anterolateral Craniofacial Resection with Orbital Exenteration.

Objective This study was aimed to evaluate health-related quality of life in patients undergoing anterolateral craniofacial resection (AL-CFR) with orbital exenteration (OE) for malignant skull base tumors and to investigate the effects of early psychiatric intervention. Design Present study is a prospective, observational study. Setting The study took place at the hospital department. Participants Twenty-six consecutive patients were selected who underwent AL-CFR with OE at our hospital between 2005 and 2015. Main Outcome Measures Health-related quality of life was assessed preoperatively and 3, 6, 12, and 24 months after surgery using the Hospital Anxiety and Depression Scale (HADS) and medical outcomes study 8-items Short Form health survey (SF-8). In all cases, psychiatric intervention was organized by the consultation liaison psychiatry team preoperatively and postoperatively. Results Ten (38.0%) of the 26 patients died and 16 (62.0%) were alive and disease-free at the end of the study. The 3-year overall and disease-free survival rates were 64.9% and 53.3%, respectively. Twenty-one patients (80.8%) developed psychiatric complications after surgery and needed treatment with psychotropic medication. Before surgery, 28% of patients had HADS scores ≥8 for anxiety and 20% had scores ≥8 for depression. Seven of the eight items in the SF-8 were significantly lower than those for the general Japanese population. However, scores for all the SF-8 items gradually improved during postoperative follow-up, reaching approximately 50 points, which is the national standard value, at 2 years after surgery. Conclusions Craniofacial resection with OE was feasible and well tolerated in patients with malignant skull base tumors who received early psychiatric intervention to decrease the considerable psychological impact of this procedure.

Therapeutic angiogenesis using autologous adipose-derived regenerative cells in patients with critical limb ischaemia in Japan: a clinical pilot study.

Adipose-derived regenerative cell (ADRC) is a promising alternative source of autologous somatic stem cells for the repair of damaged tissue. This study aimed to assess the safety and feasibility of autologous ADRC implantation for therapeutic angiogenesis in patients with critical limb ischaemia (CLI). A clinical pilot study-Therapeutic Angiogenesis by Cell Transplantation using ADRCs (TACT-ADRC) study-was initiated in Japan. Adipose tissue was obtained by ordinary liposuction method. Isolated ADRCs were injected into the ischaemic limb. We performed TACT-ADRC procedure in five patients with CLI. At 6 months, no adverse events related to the TACT-ADRC were observed. No patients required major limb amputation, and ischaemic ulcers were partly or completely healed during the 6-month follow-up. In all cases, significant clinical improvements were seen in terms of rest pain and 6-min walking distance. Numbers of circulating CD34+ and CD133+ cells markers of progenitor cell persistently increased after ADRC implantation. The ratio of VEGF-A165b (an anti-angiogenic isoform of VEGF) to total VEGF-A in plasma significantly decreased after ADRC implantation. In vitro experiments, cultured with ADRC-conditioned media (CM) resulted in increased total VEGF-A and decreased VEGF-A165b in C2C12 cells, but not in macrophages. ADRC-CM also increased CD206+ cells expression and decreased TNF-α in macrophages. Autologous ADRC implantation was safe and effective in patients with CLI and could repair damaged tissue via its ability to promote angiogenesis and suppress tissue inflammation.

Multiple Thrombi during Microvascular Anastomosis Caused by Decreased Antithrombin Activity: A Case Report.

With recent advances in microsurgical instruments and technique, microvascular anastomosis has become a universal surgical technique; however, thrombosis still presents in a number of cases. Tension, twisting, and compression to the anastomotic site are the main causes of thrombus; however, disorder of the coagulation-fibrinolysis system also need to be considered. To date, only few reports exist regarding thrombosis caused by disorder of coagulant system in microvascular anastomosis. Here we report our 3 cases in which multiple thrombus formation occurred intraoperatively caused by decrease of antithrombin (AT) activity. AT activity was measured twice a day after vascular anastomosis: after surgery and up to 3 days after surgery. Thrombosis was not observed in any of the 3 patients intraoperatively after the transfusion, or thrombosis was not observed in any of 3 patients intraoperatively after the transfusion or postoperatively, and no other complications were observed. In these 3 cases, the thrombus was not caused by technical error or other previously described factors. The observed intraoperative decrease in AT activity was thought to be caused by thrombus formation. It is important that microsurgeons are reminded that disorders of the coagulation-fibrinolysis system could cause thrombosis.

Correlation between blood flow, tissue volume and microvessel density in the flap.

The purpose of this study was to assess the correlation between tissue volume and blood flow of the flap in an animal model. Using animal model, tissue volume can be attenuated, and precise change of blood flow could be evaluated. We further investigate the relationship between blood flow and vascular density in the tissue. In this study, we assessed flap conductance (ml/min/mm Hg) as to evaluate the conductivity of blood flow into the flap. Japanese white rabbit was used (n = 7) for this study. The amount of blood flow of jejunal and latissimus dorsi muscle (LD) flaps was measured while removing the distal portion of the flap sequentially. Conductance at each time was calculated from blood pressure and blood flow volume. The tissue volume at each time was also measured. The correlation between conductance and volume was analyzed using a linear mixed model. Immunohistochemical evaluation of microvessel densities (MVD) in these tissues was also performed for CD31/PECAM1 positive area. Conductance and tissue volume were significantly correlated in both jejunal and LD flaps. As the volume increases by 1 cm3, the conductance increased significantly by 0.012 ml/min/mm Hg in jejunum, and by 0.0047 ml/min/mm Hg in LD. Mean MVD was 1.15 ± 0.52% in the jejunum and 0.37 ± 0.29% in the LD muscle. In this study, we revealed that flap conductance is proportional to volume and proportional constant is different between the type of tissue. It suggests that the difference of MVD creates the unique conductance of each tissue.