The isolation of a fibroblast growth inhibitor associated with perigraft seroma

[Treatment of complications after arteriovenous access surgery]

The choice of potential options for an arteriovenous (AV) access is limited for each individual patient. Complications shorten the maximum life span of any AV access. This paper stresses the importance of recognizing complications in time so as to initiate early and adequate therapy which are explained in further detail. Existing vascular accesses should be used as long as possible while maintaining further alternatives for future AV access surgery.

Leakage of the Arterial Prosthesis of an Impella RVAD

Seromas occurring around a vascular graft are a rare complication. We report a life-threatening plasma leakage that occurred through the polytetrafluoroethylene vascular prosthesis of an Impella right ventricular assist device (Impella RD [Impella Cardiosystems GmbH, Aachen, Germany]) implanted in a 62-year-old patient with acute right ventricular failure after cardiac transplantation. The leakage became progressively massive. Weaning the patient from the right ventricular assist device was not possible. The prosthesis was thus wrapped within a pericardial patch to contain the leakage. Three days later the patient could be successfully weaned and the pump was removed. The clinical evolution was favorable.

Implant infections: a haven for opportunistic bacteria

The insertion of implants and medical devices has emerged as a common and often life-saving procedure. A current estimate of the rate of total hip replacement in the world is approximately one million a year, and knee replacements more than 250000. More than 30% of hospitalized patients have one or more vascular catheters in place. More than 10% of hospitalized patients have an indwelling urinary catheter. Some patients require multiple joint replacements. In the United States, approximately 2 million nosocomial infections cost nearly $11 billion annually. Exposure to invasive medical devices is one of the most important risk factors.(1)Devices predispose to infection by damaging or invading epithelial or mucosal barriers and by supporting growth of micro-organisms, thus serving as reservoirs. Invasive medical devices impair host defence mechanisms and, when contaminated, can result in resistant chronic infection or tissue necrosis, the major objections to extended use of implant devices. Implant devices today account for approximately 45% of all nosocomial infections.(2)Implant infections are extremely resistant to antibiotics and host defences and frequently persist until the implant is removed, which is the standard therapy. Tissue damage caused by surgery and foreign body implantation further increases the susceptibility to infections, activates host defences and stimulates the generation of inflammatory mediators; these are enhanced by bacterial activity and toxins.(3)The ability of bacteria such as Staphylococcus epidermidis, which are otherwise virtually avirulent, to escape from host defences and antibiotic therapy, has led to the development of alternative methods of control such as infection-resistant materials acting as antimicrobial drug-delivery systems. By these methods, there is a sustained delivery of antimicrobial drugs into the local micro-environment of implants, which avoids systemic side-effects and exceeds usual systemic concentrations by several orders of magnitude. Bioengineering of hybrid implant materials in order to achieve optimal performance and to prevent inflammatory reactions and interface cellular disorganization is a field undergoing rapid development. Hybrid materials that slowly deliver antimicrobial drugs may reduce implant infections in the future.

Heparin as a risk factor for perigraft seroma complicating the modified Blalock-Taussig shunt

OBJECTIVE

The purpose of this study was to determine the risk factors associated with the occurrence of perigraft seromas complicating systemic-to-pulmonary polytetrafluoroethylene grafts.

METHODS

Clinical and perioperative variables were reexamined, blinded for the outcome variable perigraft seroma, in 60 patients undergoing 67 consecutive graft procedures in a 3.5-year period.

RESULTS

Eight cases of perigraft seroma were diagnosed in six patients. Univariate analysis revealed age (p = 0.02), a diagnosis of pulmonary atresia with ventricular septal defect and systemic-pulmonary collaterals (p = 0.001), reimplantation of collaterals during the procedure (p < 0.001), and intravenous heparin administered after operation (p < 0.0001) as risk factors for symptomatic perigraft seroma. Multivariable analysis defined heparin as the only significant factor associated with symptomatic perigraft seroma. Consolidation of the upper lobe on chest radiograph, ipsilateral to the shunt, directly after operation (p = 0.01), but especially 8 to 10 days after operation (p < 0.0001), or the need for prolonged drainage of pleural fluid (p < 0.0001) were correlated with the occurrence of perigraft seroma. Perigraft seroma led to four early rethoracotomies in three patients and to accelerated corrective surgery in three cases. Consolidation and absent perfusion of lung segments persisted in two patients.

CONCLUSIONS

Our data suggest that the use of heparin leads to an increased risk of perigraft seroma, complicating systemic-pulmonary polytetrafluoroethylene grafts. Prolonged pleural drainage and/or postoperative consolidation of the upper lobe indicate the development of symptomatic perigraft seroma. Treatment is controversial and results are unpredictable. Expectative management seems to be justified so long as permitted by the clinical condition.

Basic science and clinical aspects of wound healing in glaucoma filtering surgery

Success of glaucoma filtration surgery is influenced by the wound healing response. Attention has been focused on pharmacological agents to control a process that leads to excessive scarring and eventual failure of glaucoma filtration surgery. Several agents, including 5-fluorouracil and mitomycin C, as well as other antiproliferative drugs will be discussed. Newer antifibrotic agents and novel drug delivery systems are under development in tissue culture and animal models in an effort to improve efficacy and safety. This article summarizes current treatment modalities and future prospects to prevent excessive wound healing and improve the success of glaucoma filtration surgery.

Bacterial products primarily mediate fibroblast inhibition in biomaterial infection

PURPOSE

The stimulation of fibroblast growth is essential for the normal healing and tissue integration of biomaterials. The local elevation of proinflammatory mediators in infected perigraft fluid (PGF) may inhibit this growth. We sought to determine whether infected PGF inhibited fibroblast growth, and, if so, whether this was primarily dependent on the biomaterial, bacteria, or host.

METHODS

In vivo Dacron or expandable polytetra-fluoroethylene (ePTFE) grafts, sterile or colonized with slime-producing (RP-62A, viable or formalin-killed) or nonslime-producing (RP-62NA) Staphylococcus epidermidis (1 x 10(7) CFU/cm2), were implanted in Swiss Webster mice, and the PGF was harvested at 7 and 28 days. Antibodies to tumor necrosis factor alpha, interleukin 1 alpha, interferon gamma (7 micrograms/day), and indomethacin (50 micrograms/day) were administered by microinfusion pumps for 7 days and the PGF was harvested. Inhibition of the proinflammatory mediators was confirmed by enzyme-linked immunosorbant assay. The nontreated, heat-treated, or trypsin-digested in vivo PGF was incubated with an in vitro [3H]thymidine murine fibroblast (ATCC CCL-12) proliferation assay.

RESULTS

Fibroblast inhibition was significant at 7 and 28 days with infected PGF incubation compared with sterile and was not dependent on bacterial slime production or viability. Dacron sterile PGF did not significantly inhibit fibroblasts compared with control, whereas sterile ePTFE stimulated (P < 0.05) fibroblasts. Treatment of the PGF with proinflammatory cytokines, heat, and trypsin failed to reverse fibroblast inhibition in the infected state.

CONCLUSION

Biomaterial infection is associated with fibroblast inhibition that is dependent primarily on bacterial products and not the host or biomaterial. Conservative intervention strategies for graft infection need to address the problem of poor healing as well as bacterial clearance.

Cardiac tamponade after a systemic-pulmonary shunt complicated by serous leakage

A newborn baby with complex congenital heart disease had severe persistent pericardial effusion after a systemic-pulmonary shunt. Pericardiocentesis and pericardiotomy could not stop pericardial leakage. At reoperation, topical application of a fibrin glue resulted in resolution of the leak and avoided replacement of the graft.

Acute perigraft seroma simulating anastomotic bleeding of a PTFE graft applied as an arteriovenous shunt for hemodialysis

Perigraft seroma is an uncommonly reported complication of polytetrafluoroethylene grafts applied as an arteriovenous shunt for hemodialysis. It usually presents as a soft tissue swelling around the arterial end of the graft and occurs within 30 days after implantation. An unusual presentation of perigraft seroma occurring immediately after implantation is reported herein.