Ulceration of the hand secondary to a radial arteriovenous fistula: a model for varicose ulceration.

A patient in whom a radial arteriovenous fistula was constructed in preparation for haemodialysis subsequently developed ulceration on the dorsum of the hand. The lesion failed to heal despite antibiotic treatment, and so the fistula was closed. The lesion healed within three weeks. Subsequent construction of a fistula at the right wrist was followed 12 months later by the development of similar ulceration of the right hand. This complication of arteriovenous fistulas is similar to varicose ulceration of the leg and provides a unique opportunity to study the effects of sustained venous hypertension on the skin.     

Arteriovenous fistulas after replantation surgery

The delayed appearance of congenital arteriovenous fistula precipitated by local trauma is a rare event. However, these reports may provide some insight into pathogenetic mechanisms responsible for the opening of subclinical arteriovenous communications. This case of multiple arteriovenous fistulas in a previously "normal" hand followed a sharp, incomplete amputation at the wrist level with replantation.     

彩色多普勒超声在血液透析动静脉内瘘功能评估及病变检测中的应用探究

目的:探讨彩色多普勒超声在血液透析动静脉内瘘功能评估及病变检测中的应用价值。方法:选取2013年3月至2016年3月于我院接受血液透析的终末期肾病患者62例作为研究对象,采用二维超声观察动静脉内瘘的一般情况,采用彩色多普勒观察血流方向、速度以及充盈情况,对检测结果进行比较。结果:自体动静脉内瘘成形术后桡动脉管径(RAD)、桡动脉血流量(RVF)、头静脉管径(CVD)均较术前有所提高,各项指标随时间延长而逐渐增高,差异有统计学意义(P0.05)。62例血液透析患者中,共有41例(66.13%)患者动静脉内瘘通畅,21例(33.87%)患者出现动静脉内瘘并发症,其中血栓形成9例(14.52%)、动静脉瘘狭窄7例(11.29%)以及静脉瘤状扩张5例(4.84%)。血栓形成组头静脉血管内径(D)、吻合口D、最大峰值流速(PSV)及血流阻力指数(RI)、桡动脉D、PSV及RI均较正常组有显著差异。血栓形成、动静脉瘘狭窄患者上述参数及血流量与正常组比较有显著差异(P0.05)。结论:彩色多普勒超声可有效监测血液透析患者动静脉内瘘病变发生情况,对其结构功能进行直接观察的同时还可明确诊断动静脉内瘘并发症。     

Secondary expansion of a replanted scalp salvaged by an intrinsic arteriovenous shunt.

1. Although scalping injuries reported in most large series rarely involve young children, partial scalp replantation, even in a 2-year-old boy after a dog-bite avulsion, should also be warranted. However, technical difficulties because of the diminutive vasculature can be expected. 2. Unconventional methods for reestablishing inflow or outflow for the replanted scalp may become the only practical alternative and must not be overlooked. In this case, an arteriovenous shunt between the frontal branch of the superficial temporal artery within the amputated part itself to a more distal scalp vein at the superior edge of the fragment allowed high-output flow to maintain patency after recurrent thromboses of the conventional superficial temporal arterial anastomosis. This fistula was assumed to be the major contributor to nutrient flow of the remaining scalp, as the parietal branch was truncated along the margin of the avulsion. 3. Delayed tissue expansion is also an option. In this case, delayed expansion of the replanted scalp that survived allowed elimination of the skin grafts needed to cover areas where necrosis ensued, restoration of the anterior hairline, and resulted in a more normal appearance.     

Tissue engineering of cultured skin substitutes

Skin replacement has been a challenging task for surgeons ever since the introduction of skin grafts by Reverdin in 1871. Recently, skin grafting has evolved from the initial autograft and allograft preparations to biosynthetic and tissue-engineered living skin replacements. This has been fostered by the dramatically improved survival rates of major burns where the availability of autologous normal skin for grafting has become one of the limiting factors. The ideal properties of a temporary and a permanent skin substitute have been well defined. Tissue-engineered skin replacements: cultured autologous keratinocyte grafts, cultured allogeneic keratinocyte grafts, autologous/allogeneic composites, acellular biological matrices, and cellular matrices including such biological substances as fibrin sealant and various types of collagen, hyaluronic acid etc. have opened new horizons to deal with such massive skin loss. In extensive burns it has been shown that skin substitution with cultured grafts can be a life-saving measure where few alternatives exist. Future research will aim to create skin substitutes with cultured epidermis that under appropriate circumstances may provide a wound cover that could be just as durable and esthetically acceptable as conventional split-thickness skin grafts. Genetic manipulation may in addition enhance the performance of such cultured skin substitutes. If cell science, molecular biology, genetic engineering, material science and clinical expertise join their efforts to develop optimized cell culture techniques and synthetic or biological matrices then further technical advances might well lead to the production of almost skin like new tissue-engineered human skin products resembling natural human skin.     

Development of arteriovenous anastomoses in the skin of the chicken and the influence of environmental temperature

Posthatching differentiation of arteriovenous anastomoses (AVAs) and the effect of heat exposure (38 degrees C) and cold acclimation (2-3 degrees C) on AVA density were studied in naked skin areas (eyelids, comb, wattles) of chickens. The AVAs were identifiable in the newly hatched chick, but they were extremely simple. The number of cell layers in the wall of the AVAs increased from two at hatching to four to five in the 5-month-old chickens. The density of the AVAs increased significantly during posthatching maturation. Cold acclimation of the chickens increased the density of AVAs by a factor of 2.1-3.2. Daily heat exposure also increased the density of AVAs significantly in the eyelids but had no effect in the other skin areas. Heat and cold had only minor effect on the vascularity of the skin; the only significant change recorded was a slight increase in the number of blood vessels in the wattles of the cold-acclimated chickens.     

Enhanced function of cultured epithelium by genetic modification: Cell-based synthesis and delivery of growth factors

Skin substitutes, containing cultured keratinocytes of the epidermis (autologous or allogeneic cells), have been used in the treatment of severe burns and other defects of the skin such as chronic ulcers. Our goal is to enhance the functions of the cells used in these skin substitutes by genetic modification. We propose to develop a genetically modified skin graft which would function as a cell-based vehicle for the local synthesis and delivery of wound-healing growth factors. Using retroviral-mediated gene transfer, we have introduced stable copies of the genes encoding platelet-derived growth factor (PDGF-A) or insulin-like growth factor-1 (IGF-1) into cultured human diploid keratinocytes. After stable integration of these genes, the cells secreted significant levels of these growth factors, 744 ng and 502 ng/10(7) cells/24 h for PDGF-A and IGF-1, respectively. The modified cells were grown to confluence, detached as a multicell-layered epithelial sheet, and transplanted to athymic mice.Seven days after transplantation, grafts secreting PDGF-A or IGF-1 differentiated into a stratified epithelium comparable to unmodified cells. Most importantly, the newly synthesized connective tissue layer subjacent to the PDGF-A-modified grafts was significantly thicker and showed an increase in cellularity, vascularity, type I collagen, and fibronectin deposition when compared to control grafts of unmodified cells or grafts expressing IGF-1.These results demonstrated that the function of the cells of a skin substitute can be enhanced by genetic modification and show that PDGF-A secretion from these cells can mediate changes to the cellular, vascular, and extracellular matrix composition of the adjacent dermal tissue. Moreover, these results suggest that a cell-based method for growth factor synthesis and delivery may be a useful approach to promoting tissue repair. (c) 1996 John Wiley & Sons, Inc.     

高频彩色多普勒超声监测维持性血透内瘘功能的临床应用现状

该文综述了应用高频彩色多普勒超声在血透患者动静脉内瘘（ AVF）术前进行目标血管的选择,检查、筛选与定位,术后可用于监测动静脉内瘘（ AVF）功能、流量、流速与各种并发症,以利于提高血透患者的生活质量与生存率。     

Use of Internal Arteriovenous Fistula in Home Haemodialysis

Five patients with previous experience of home haemodialysis (lasting one to two years) had internal arteriovenous fistulae created in a previously non-cannulated limb. After training of the spouses or patients to insert the needles, the arteriovenous cannulas were removed and the patients maintained on fistula dialysis in the home, unattended, overnight, for periods of 1 to 11 months (total patient experience of 30 months). All patients expressed a preference for the arteriovenous fistula, and no significant medical complications have been noted to date.The safe use of a blood pump in the home, overnight, was achieved by the addition of an extra monitor on the outflow (arterial) blood line.     

Systemic arteriovenous fistula leads to pulmonary artery remodeling and abnormal vasoreactivity in the fetal lamb

Several cases of systemic arteriovenous fistula diagnosed in the human fetus have been associated with the postnatal development of persistent pulmonary hypertension. The aim of this study was to determine the effects of a prenatally created systemic arteriovenous fistula on the structure and reactivity of the pulmonary circulation in the fetal lamb. A fistula between the jugular vein and carotid artery was created in fetal lambs at 119-124 days of gestation. At delivery (134-139 days), left pulmonary artery (LPA) pressure was increased in the fistula group (n = 12) compared with controls (n = 11, P < 0.01). The pulmonary vascular resistance was significantly higher in the fistula group (P < 0.05), whereas mean LPA blood flow was not statistically different between the two groups. Morphometric analysis of the pulmonary vascular bed revealed an increase in the number of peripheral muscular arteries, together with an increase in pulmonary arterial medial thickness in the fistula group. There was no difference in the relative number or size of intraacinar arteries. In vitro organ bath studies on pulmonary arterial rings showed impaired endothelium-dependent relaxation in the fistula group compared with controls. However, endothelial nitric oxide synthase protein expression was similar in both groups, whereas endothelium-independent relaxation to sodium nitroprusside was greater in the fistula group compared with controls. A systemic arteriovenous fistula leads to both structural and functional alteration of the pulmonary vasculature, which might lead to the development of persistent pulmonary hypertension after birth.     

Effects of wall distensibility in hemodynamic simulations of an arteriovenous fistula

Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. The current study presents fluid–structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10–15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50 % compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to “normal” values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae.     

The role of serum imbibition for skin grafts

Numerous studies of grafted skin suggest that full-thickness skin grafts are nourished by exudate from the recipient bed called a serum imbibition. However, whether serum imbibition by itself is sufficient for nourishment of skin grafts has not been shown definitely and directly. To clarify the role of serum imbibition, we performed a comparative study between 20 skin grafts and 20 musculocutaneous flaps. The nourishment of the cell in the skin graft is by serum imbibition. That in musculocutaneous flaps is mainly derived from blood supply. We evaluated the nourishment by means of the unique characteristics of the cell cycle. Once cells are put into a synthetic phase, they cannot reverse or stop the progress of the cell cycle. To take advantage of this characteristic of the cell cycle, prewounding methods (40 flaps were lifted once and put back to the original sites prior to the evaluation) were intended for the cells in pre-elevated skin to turn into a proliferating phase. Cells were examined by antibody against proliferating cell nuclear antigen immunohistologically, to determine whether they had turned into the proliferating phase or not. After 3 days, all flaps were reelevated; half (20 flaps) had their muscle layer and the neurovascular bundle removed to make a full-thickness skin graft. The rest (20 flaps) were only lifted. They were sutured back to the original sites. Ten skin grafts and musculocutaneous flaps each were harvested at 3 hours (1st day) and at 11 days (11th day) after the second operation. Bromodeoxyuridine, which is a thymidine analog and is taken into the cells in the synthetic phase, was introduced intraperitoneally 2 hours before the harvest. All flaps and grafts were evaluated histologically and immunohistologically. Proliferating cell nuclear antigen analysis showed that the prewounding method induced the cells of skin grafts and musculocutaneous flaps to proliferate before the implantation. Regarding the bromodeoxyuridine uptake, no significant differences could be seen between skin grafts and musculocutaneous flaps irrespective of their different nourishment. No structural changes, such as degenerative or necrotic, could be seen at the hair follicle and other glands even at the 11th day. Almost all of the layers of skin grafts survived as long as they were checked by light microscopy (hematoxylin and eosin stain). No differences could be seen between musculocutaneous flaps and skin grafts or between the 1st and 11th days in this study. We concluded that serum imbibition is sufficient for nourishment of skin grafts, just as blood supply is sufficient for nourishment of musculocutaneous flaps.     

Diagnostic difficulties in differentiating of arteriovenous fistula -- case report

Arteriovenous carotid-cavernous fistula is an abnormal connection between the dural branches of carotid artery or vertebral artery and the dural sinuses. Its clinical manifestations can resemble the crucial signs of thyroid orbitopathy, an inflammatory disorder of the orbit associated with Graves' disease. Therefore, differential diagnosis of thyroid orbitopathy and the congestion of the orbit seen in arteriovenous fistula is often clinically and radiologically confused. This is the case report of the simultaneous occurrence of dural arteriovenous fistula in 59 years old woman. The first manifestation was unilateral exophthalmia. After Computer Tomography and Magnetic Resonance Imaging were performed, the preliminary diagnosis of thyroid orbitopathy was established. The response of eye disorder to corticosteroid treatment resulted in evident deterioration. This prompted a reconsideration of the diagnosis and a new evaluation of the patient with sensitive techniques, leading to the final diagnosis of arteriovenous fistula.     

Biomechanical, morphological and zero-stress state characterization of jugular vein remodeling in arteriovenous fistulas for hemodialysis

While the role of hemodynamic variables on the development of intimal hyperplasia in arteriovenous fistulas for hemodialysis has been examined, less is known about the intramural biomechanical factors. In this study, arteriovenous fistulas were created by implantation of e-PTFE grafts between carotid artery and jugular vein in healthy pigs. In vivo recordings exhibited a three-fold pressure and flow elevation in grafted veins after fistula creation, remaining so until sacrifice. The chief morphological observation in grafted vessels was wall thickening at two weeks, serving to restore intramural stresses to homeostatic levels, and a less marked internal diameter enlargement, gradually normalizing intimal shear after four weeks. The residual strains and opening angle, specifying the zero-stress configuration, increased with differences reaching significance at twelve weeks. Association with histomorphological findings on intima, media and adventitia growth disclosed a correlation between intimal hyperplasia and opening angle increase. Elastin and cellular contents diminished opposite to collagen content, most differences occurring within the first four weeks after grafting. Inflation/extension testing showed that post-fistula the vein wall became progressively thicker and stiffer, lacking restoration of compliance to baseline levels. The present data may further our understanding of the dynamics of venous biomechanical remodeling under pressure and flow-overload conditions.     

Autogenous arteriovenous elbow fistula for haemodialysis and upper extremity ischemia

BACKGROUND: The autogenous brachiocephalic or brachiobasilic arteriovenous elbow fistula is not considered to be only the secondary haemodialysis access. In patients with an unsuitable forearm vessel bundle, it is indicated as primary access and it is the method preferred to the fistula creation using a vascular prosthesis. Its rather rare complication is the development of upper extremity ischemia. AIM: To summarise current knowledge of this fistula type and its associated complications METHODS: Review of the literature. RESULTS: The creation and maturation of the fistula and occurrence of the steal syndrome is influenced by a number of factors. The analysis and awareness of such factors will provide for creation of a suitable fistula as well as for timely complication diagnostics and treatment. CONCLUSIONS: The autogenous elbow fistula utilising the brachial artery and the cephalic or basilic vein in the upper extremity represents a high-quality haemodialysis access. Its potential complication is the occurrence of the steal syndrome. Its occurrence and manifestations do not constitute indications for ligation of the access. The gathered information shows that a suitable surgical procedure can help meet the basic rule for haemodialysis access--resolving the ischemia and maintaining the access.     

Prelaminated free flap reconstruction of complex central facial defects

This article is a review of five patients who underwent reconstruction of nasal and paranasal facial defects with prelaminated forearm free flaps. The defects resulted from thermal injury, gunshot wound, excision of tumor, and arteriovenous malformation (n = 2). The forearm flaps were based on the radial artery (n = 4) and ulnar artery (n = 1) and were prelaminated with grafts of skin and cartilage. All flaps were successfully transferred to the face, but revisions were needed to separate the subunits and improve appearance. A prelaminated free flap should be considered for a patient requiring reconstruction of a complex central facial defect.     

SUCCESSFUL SURGICAL MANAGEMENT OF CONGENITAL ARTERIOVENOUS FISTULA OF THE SUBCLAVIAN ARTERY: CASE REPORT

A 10-month-old infant was found to have an isolated congenital arteriovenous fistula between the right subclavian artery and vein. Ligation of the fistula resulted in complete anatomic correction and rapid resolution of cardiomegaly.     

Arteriovenous fistula after intervertebral disk surgery at L4-L5

We describe a 34-year-old woman who had symptoms of heart failure due to an arteriovenous fistula between the right iliac artery and the inferior vena cava caused by surgery for a herniated intervertebral disk. The literature is reviewed. An intra-arterial placed covered stent was successfully used to close the fistula.     

Prolongation of skin allograft survival after neonatal injection of donor bone marrow and epidermal cells

Composite-tissue (e.g., hand allograft) allotransplantation is currently limited by the need for immunosuppression to prevent graft rejection. Inducing a state of tolerance in the recipient could potentially eliminate the need for immunosuppression but requires reprogramming of the immunological repertoire of the recipient. Skin is the most antigenic tissue in the body and is consistently refractory to tolerance induction regimens using bone marrow transplantation alone. It was hypothesized that tolerance to skin allografts could be induced in rats by injecting epidermal cells with bone marrow cells during the first 24 hours of life of the recipients. Brown Norway rats (RT1n) served as donors for the epidermal cells, bone marrow cells, and skin grafts. Epidermal cells were injected intraperitoneally and bone marrow cells were injected intravenously into Lewis (RT1l) newborn recipient rats. In control groups, recipients received saline solution with no cells (group I, n = 12), bone marrow cells only (group II, n = 15), or epidermal cells only (group III, n = 15). In the experimental group (group IV, n = 18), recipients received epidermal and bone marrow cells simultaneously. Skin grafts were transplanted from Brown Norway (RT1n) rats to the Lewis (RT1l) rats 8 weeks after cell injections. Skin grafts survived an average of 8.5 days in group I (10 grafts), 9.2 days in group II (12 grafts), and 12 days in group III (14 grafts). Grafts survived 15.5 days (8 to 26 days) in group IV (15 grafts). The difference was statistically significant (p < 0.05). Hair growth was observed in some accepted grafts in group IV but never in the control groups. This is the first report of prolonged survival of skin allografts in a rat model after epidermal and bone marrow cell injections. Survival prolongation was achieved across a major immunological barrier, without irradiation, myeloablation, or immunosuppression. It is concluded that the presentation of skin-specific antigens generated a temporary state of tolerance to the skin in the recipients that could have delayed the rejection of skin allografts.     

Postoperative irradiation after reconstructive surgery: comparative study of radiosensitivity between free-skin grafts and skin flaps

Radiation effects after reconstructive surgery (free-skin grafts and skin flaps) were studied in the rat, and the optimum time for irradiation was determined. The radiosensitivity of both free-skin grafts and skin flaps showed the same trend depending on time of irradiation after operation. The grafts or flaps irradiated in the hypervascular stage showed severe reactions to irradiation, whereas those irradiated in the hypovascular stage showed milder reactions in gross and microangiographic observation. Vascular damage should be given primary consideration when deciding the proper time for irradiation after reconstructive surgery. In general, free-skin grafts showed more severe reactions than skin flaps, especially in the grafts irradiated in the early stage after operation. The experimental results of this study cannot be readily transferred to a clinical setting, but they suggest that postoperative irradiation could be begun 3 to 4 weeks after operation with respect to graft or flap survival, and the results of the clinical cases almost coincide with these experimental results.