Biaxial stretching of polytetrafluoroethylene in industrial scale to fabricate medical ePTFE membrane with node-fibril microstructure

Expanded polytetrafluoroethylene (ePTFE) is promising in biomedical fields such as covered stents and plastic surgery owing to its excellent biocompatibility and mechanical properties. However, ePTFE material prepared by the traditional biaxial stretching process is with thicker middle and thinner sides due to the bowing effect, which poses a major problem in industrial-scale fabrication. To solve this problem, we design an olive-shaped winding roller to provide the middle part of the ePTFE tape with a greater longitudinal stretching amplitude than the two sides, so as to make up for the excessive longitudinal retraction tendency of the middle part when it is transversely stretched. The as-fabricated ePTFE membrane has, as designed, uniform thickness and node-fibril microstructure. In addition, we examine the effects of mass ratio of lubricant to PTFE powder, biaxial stretching ratio and sintering temperature on the performance of the resultant ePTFE membranes. Particularly, the relation between the internal microstructure of the ePTFE membrane and its mechanical properties is revealed. Besides stable mechanical properties, the sintered ePTFE membrane exhibits satisfactory biological properties. We make a series of biological assessments including in vitro hemolysis, coagulation, bacterial reverse mutation and in vivo thrombosis, intracutaneous reactivity test, pyrogen test and subchronic systemic toxicity test; all of the results meet the relevant international standards. The muscle implantation of the sintered ePTFE membrane into rabbits indicates acceptable inflammatory reactions of our sintered ePTFE membrane fabricated on industrial scale. Such a medical-grade raw material with the unique physical form and condensed-state microstructure is expected to afford an inert biomaterial potentially for stent-graft membrane.

First-in-man use of an Indian-made balloon-expandable covered Zephyr stent and intermediate-term follow-up

Covered stent is used in large-vessel angioplasty in anticipation of vessel wall injury. Apart from aortic coarctation, they are also used in dysfunctional right ventricular outflow conduits and find a recent role in transcatheter sinus venosus defect closure. Different methods of covering stents include glue fixation, sutureless lamination, sandwich, and sintering lamination. Covered Zephyr (Sahajanand laser technology limited, Gandhinagar, India) is a new Indian-made expanded polytetrafluoroethylene-covered balloon expandable cobalt-chromium stent. Its unique C and S links prevent foreshortening. We report the first-in-man use of this new stent in severe discrete postsubclavian coarctation of aorta and its short-term follow-up imaging.

Transitional changes of spacer materials used in carbon-ion radiation therapy

PURPOSE

To evaluate the imaging findings and transitional changes in spacer materials used in carbon-ion radiation therapy MATERIALS: Medical records were retrospectively reviewed, and the maximum thickness, volume, and CT value of spacers were calculated from CT scans. Procedure-related complications were recorded.

RESULTS

A spacer was surgically placed in six patients in retroperitoneal, presacral, or peritoneal sites. The spacer material was polyglycolic acid (PGA) in four patients and expanded polytetrafluoroethylene (ePTFE) in two patients. The thickness of PGA spacers showed no changes in any patients within 4 weeks, but increased within 6 weeks in one patient and was unchanged or decreased in the remaining patients. PGA spacer volume decreased gradually after placement in three of four patients; this was observed at 4 months in two patients and at 6 months in one patient. The mean CT value of PGA spacers was 83 HU just after placement, and decreased gradually thereafter. Air was seen in the PGA spacers of two patients. Neither ePTFE spacer showed volume changes over time, and the mean CT value was low (mean, -53.7 HU) just after placement but increased rapidly to 145 HU at 2 months.

CONCLUSION

Spacer imaging findings may vary according to type and may change over time. Familiarity with these features is beneficial for diagnostic radiologists.

A case study of an undetected expanded polytetrafluoroethylene implant material mimicking a nasal dorsal hump

Augmentation rhinoplasty using alloplastic materials is a relatively standard procedure in Asian patients. Expanded polytetrafluoroethylene (ePTFE) is one of the commonly used alloplastic materials because it has a high biocompatibility and is easy to handle. Recently, a patient who had previously undergone augmentation rhinoplasty using ePTFE as the implant material visited our clinic. She had the implant material surgically removed after three years and visited our clinic with a nasal dorsal hump. The patient underwent revision rhinoplasty at our institution. Unexpectedly, we found some ePTFE material that was not identified on the preoperative X-rays. After removing the ePTFE material, the nasal dorsal hump was corrected, and we did not need to perform a nasal dorsal hump reduction.

Waterproof and Breathable Wound Dressing Composited By Expanded Polytetrafluoroethylene Backing and Hydrogel

Wound dressings with waterproof, breathable and bacterial-resistant properties are still rarely realized. In this work, a newly hydrogel-based dressing is designed with a backing of expanded polytetrafluoroethylene (ePTFE) film. The ePTFE grafting with polyvinylpyrrolidone (PVP) brush is composited with hydrogel successfully with an adhesion energy of ∼80 kJ/m² . In this resultant composite, the ePTFE backing contributes excellent breathability, water resistance and bacterial barrier property. The water vapor transmission rate of the composite is 4.83 × 10³  g/m² ·24 h, which can maintain the mosit evironment of wound and relive pain by evaporating water. Notably, it can withstand 500 mm water column for over 300 s, which is obviously better than the commonly used nonwoven fabric backing materials. It can also prevent the invasion of bacteria, because the pores of ePTFE backing are smaller than those of most common bacterial. As a result, the composite with an ePTFE film backing has a positive effect in accelerating wound healing, promoting the reconstruction of intact epidermis and reducing inflammation. This article is protected by copyright. All rights reserved.

Constrictive pericarditis caused by pericardial substitution using expanded polytetrafluoroethylene

BACKGROUND

Expanded polytetrafluoroethylene (ePTFE) is commonly used as a pericardial substitute during cardiac surgery to prevent cardiac injury during re-sternotomy. However, although rare, constrictive pericarditis associated with ePTFE has been reported.

MATERIAL, METHODS AND RESULTS

Here, we report a rare case of constrictive pericarditis developed due to severe restriction of cardiac motion associated with the ePTFE membrane used as a pericardial substitute. Hemodynamic improvement has been achieved by surgical removal of the ePTFE membrane and exudates within the overlapped portion of the ePTFE membranes, and dissection of the epicardial fibrous thickening.

CONCLUSION

Considering the risk of constrictive pericarditis, we believe that the use of ePTFE membranes as a pericardial substitute should be carefully indicated for only selected patients.

Hand-sewn expanded polytetrafluoroethylene valved conduit for right ventricular outflow tract reconstruction

OBJECTIVES

Due to the lack of large-sized pulmonary valved conduit products in clinical practice, hand-sewn expanded polytetrafluoroethylene (ePTFE) valved conduit has been used for right ventricular outflow tract (RVOT) reconstruction in many heart centers around the world. This study aims to summarize the early results of the ePTFE valved conduit and the sewing technology of the conduit in combination with the latest progress, and to provide a reference for the application of ePTFE valved conduit.

METHODS

A total of 21 patients using ePTFE valved conduit for RVOT reconstruction in the Second Xiangya Hospital, Central South University from October 2018 to October 2020 were prospectively enrolled in this study. The age at the implantation of the conduit was 4.3 to 43.8 (median 15.1) years old, with weight of (38.9±4.1) kg. In this cohort, 14 patients underwent re-reconstruction of RVOT, including 12 patients with pulmonary regurgitation at 6.3 to 31.0 (median 13.8) years after tetralogy of Fallot (TOF) repair, and 2 patients with failed bovine jugular vein conduit (BJVC). Seven patients underwent Ross operations. Among them, 3 were for aortic valve stenosis, 2 were for aortic regurgitation, and 2 were for both stenosis and regurgitation. The ePTFE valved conduits were standard hand-sewn during the surgery. The 3 leaflets were equal in size with arc-shaped lower edge of the valve sinus. The free edge of the valve leaflets was straight with the length of about 1 mm longer than the diameter. The height of the valve sinus was 4/5 of the diameter. The junction of the valve leaflet was 3/4 of the height of the sinus. The designed leaflets were then continuous non-penetrating sutured into the inner surface of Gore-Tex vessel to make a valved conduit. Valved conduits with diameter of 18, 20, and 22 mm were used in 2, 9, and 10 cases, respectively. The surgical results, postoperative recovery time, and serious complications were summarized, and the changes of postoperative cardiac function status and hemodynamic status of the conduits were investigated.

RESULTS

During the implantation of ePTFE valved conduit for RVOT reconstruction, 2 patients underwent mechanical mitral valve replacement with Ross operation, 2 patients with pulmonary regurgitation with repaired TOF underwent left and right pulmonary artery angioplasty, and 1 patient with failed BJVC underwent tricuspid valvuloplasty. The cardiopulmonary bypassing time for patients underwent re-reconstruction of RVOT was (130.9±16.9) min, with aorta clamping for 1 patient to repair the residual defect of the ventricular septum. The cardiopulmonary bypassing and aorta clamping time for Ross operation were (242.7±20.6) min and (145.6±10.5) min, respectively. The duration of postoperative ventilator assistance, intensive care unit stay, and hospital stay were 3.5 h to 7.7 d (median 17.1 h),11.2 h to 29.5 d (median 1.9 d), and 6.0 to 56.0 (median 13.0) d, respectively. All patients survived after discharge from hospital. The follow-up rate after discharge was 100% with median time at 15.0 (13.0 to 39.0) months. No death happened during the follow-up. One patient underwent stent implantation due to right coronary stenosis 2 months after Ross operation. One patient underwent balloon dilation due to right pulmonary artery ostium stenosis 1 year after re-reconstruction of RVOT. The cardiac function of all patients recovered to NYHA class I 6 months after operation. The peak pressure gradient across the valve measured by transthoracic echocardiography before discharge was (9.4±2.6) mmHg (1 mmHg=0.133 kPa), and (18.3±6.1) mmHg at the last follow-up. There was no significant increase in the gradient during the follow-up (P=0.134). No patient suffered from mild or more pulmonary regurgitation.

CONCLUSIONS

Hand-sewn ePTFE valved conduit is feasible for RVOT reconstruction. It is a promising material for RVOT reconstruction which can effectively meet clinical need. In our experience, the ePTFE valved conduit is simple to manufacture with satisfactory early outcomes.In the application of ePTFE valved conduit, attention should be paid to implantation indications and postoperative anticoagulation management, especially to the preparation details of the valved conduit, to obtain better function and durability of the conduit after implantation.

Conduits for Right Ventricular Outflow Tract Reconstruction in Infants and Young Children

Purpose of Review: Right ventricular outflow tract (RVOT) reconstruction remains a challenge due to the lack of an ideal conduit. Data and experience are accumulating with each passing day. Therefore, it is necessary to review this topic from time to time. This is a 2021 update review focused on the history, evolution, and current situation of small-sized conduits (≤ 16 mm) for RVOT reconstruction in infants and young children.

Recent Findings: Currently, the available small-sized (≤16 mm) conduits can meet most clinical needs. Homograft is still a reliable choice for infants and young children validated by a half-century clinical experience. As an alternative material, bovine jugular vein conduit (BJVC) has at least comparable durability with that of homograft. The performance of expanded polytetrafluoroethylene (ePTFE) is amazing in RVOT position according to limited published data. The past century has witnessed much progress in the materials for RVOT reconstruction. However, lack of growth potential is the dilemma for small-sized conduits. Tissue-engineering based on cell-free scaffolds is the most promising technology to obtain the ideal conduit.

Summary: No conduit has proved to have lifelong durability in RVOT position. We are far from the ideal, but we are not in a state of emergency. In-depth clinical research as well as innovation in material science are needed to help improve the durability of the conduits used in infants and young children.

Osseointegration of Dental Implants in Ridges with Insufficient Bones using Different Membranes for Guided Bone Regeneration

Background:

The use of membrane with the guided bone regeneration (GBR) has been a controversial aspect of the implant placement, which helps achieve the primary graft stabilization and inhibit early graft loss.

Objectives:

The present clinical trial was aimed to determine the results of GBR with nonresorbable (expanded polytetrafluoroethylene [e-PTFE]) and resorbable (collagen) membrane both clinically and radiographically for 2 years with dental implant placement.

Materials and Methods:

16 subjects having 32 sites for implant placement in a split-mouth pattern were included in the study. The sites for implant was prepared and grafted with the autogenous graft procured from the mandibular ramus area followed by graft coverage with either e-PTFE or collagen membrane. Various radiographic and clinical parameters were assessed for 2 years at an interval of 6 months each. The collected data were recorded for each study subject for all the implant sites and were statistically analyzed.

Results:

The mean values for periodontal probing depth at 6 months, 12 months, 18 months, and 24 months were 2.25 ± 0.17, 2.67 ± 1.84, 2.64 ± 1.21, and 3.01 ± 0.52, respectively, for the e-PTFE group. For the collagen group, the probing depth mean values at 6 months, 12 months, 18 months, and 24 months were 2.30 ± 0.14, 2.59 ± 1.76, 2.62 ± 1.30, and 2.98 ± 0.81, respectively. The corresponding clinical and radiographic parameters at all time intervals were nonsignificant on the intergroup comparison.

Conclusion:

Dental implants placed with simultaneous GBR have an acceptable survival rate at the end of 2 years irrespective of the resorbable or non-resorbable membrane used.

A Radiation-Crosslinked Gelatin Hydrogel That Promotes Tissue Incorporation of an Expanded Polytetrafluoroethylene Vascular Graft in Rats

A prosthetic vascular graft that induces perigraft tissue incorporation may effectively prevent serious sequelae such as seroma formation and infection. Radiation-crosslinked gelatin hydrogel (RXgel) mimics the chemical and physical properties of the in vivo extracellular matrix and may facilitate wound healing by promoting tissue organization. Fibroblasts cultured on RXgel actively migrated into the gel for up to 7 days. RXgels of three different degrees of hardness (Rx[10], soft; Rx[15], middle; Rx[20], hard) were prepared, and small disc-like samples of RXgels were implanted into rats. In vitro and in vivo results indicated that Rx[10] was too soft to coat vascular grafts. Thus, expanded polytetrafluoroethylene (ePTFE) vascular grafts coated with RXgel were developed using Rx[15] and Rx[20] gels, and ring-shaped slices of the graft were implanted into rats. Alpha-smooth muscle actin (αSMA) and type III collagen (Col-III) levels were detected by immunohistochemistry. Immunohistochemical staining for αSMA and Col-III demonstrated that RXgel-coated vascular grafts induced more granulation tissue than non-coated grafts on days 14 and 28 after implantation. RXgel-coated ePTFE vascular grafts may provide a solution for patients by reducing poor perigraft tissue incorporation.

A single-center retrospective analysis

INTRODUCTION

The aim of this study is to evaluate the outcome of Omniflow II biosynthetic vascular grafts as compared to synthetic expanded polytetrafluoroethylene (ePTFE) grafts in infrainguinal bypass surgery.

METHODS

A single-center, retrospective, observational study was performed reviewing patients with critical limb ischemia who underwent infrainguinal bypass surgery between 2014 and 2018. Patients characteristics, graft characteristics, and treatment outcomes were collected. Patency rates were compared using Kaplan-Meier estimates.

RESULTS

Sixty bypasses were performed in 57 patients. For above-knee surgery, six were Omniflow and 13 were synthetic. For below-knee surgery, 19 were Omniflow and 22 were synthetic. Patient characteristics between groups were similar. However, American Society of Anesthesiologists (ASA) classification scores were higher in the Omniflow group as compared to ePTFE (88% was ASA 3 or higher versus 60%; p = 0.018). Furthermore, wound, ischemia, and foot infection (WIfI) composite scores were higher in the Omniflow group (p = 0.0001). There was a trend toward more active infection at time of surgery in the Omniflow group (40 vs 22.9%, p = 0.15). At 1 year, primary patency rates were 60.0% versus 46.9% for above-knee Omniflow versus ePTFE grafts, respectively (p = 0.72). Secondary patency rates were 80.0% versus 82.5% (p = 0.89), and limb salvage rates were 83.3% versus 100% (p = 0.14). For below-knee surgery, 1- and 2-year primary patency rates in Omniflow versus ePTFE grafts were 36.0% versus 41.8% (p = 0.60) and 36.0% versus 31.1% (p = 0.87). Secondary patency rates were 66.8% versus 75.2% at 1 year (p = 0.53) and 58.8% versus 48.3% (p = 0.77) at 2 years. Below-knee limb salvage rates for Omniflow versus ePTFE after 2 years were 88.0% versus 68.3% (p = 0.28), respectively. Aneurysmal degeneration occurred in 2/25 (8%) in the Omniflow group and 0/35 (0%) in the ePTFE group. Bypass infections occurred in 2/25 (8%) in the Omniflow group and 0/35 (0%) in the ePTFE group (p = 0.09).

CONCLUSION

Omniflow bypasses were more commonly implanted in patients with higher limb infection rate as confirmed with a higher adapted WIfI score. A trend toward a higher infection rate of Omniflow grafts was observed but not statistically significant. Graft infection rates were relatively low and treatable with antibiotics. No significant difference in graft performance was observed. The choice between the two studied grafts remains based on surgeon's preference.

Surface Zwitterionization of Expanded Poly(tetrafluoroethylene) via Dopamine-Assisted Consecutive Immersion Coating

Expanded polytetrafluoroethylene (ePTFE) is one of the materials widely used in the biomedical field, yet its application is being limited by adverse reactions such as thrombosis when it comes in contact with blood. Thus, a simple and robust way to modify ePTFE to be biologically inert is sought after. Modification of ePTFE without high-energy pretreatment, such as immersion coating, has been of interest to researchers for its straightforward process and ease in scaling up. In this study, we utilized a two-step immersion coating to zwitterionize ePTFE membranes. The first coating consists of the co-deposition of polyethylenimine (PEI) and polydopamine (PDA) to produce amine groups in the surface of the ePTFE for further functionalization. These amine groups from PEI will be coupled with the epoxide group of the zwitterionic copolymer, poly(GMA-co-SBMA) (PGS), via a ring-opening reaction in the second coating. The coated ePTFE membranes were physically and chemically characterized to ensure that each step of the coating is successful. The membranes were also tested for their thrombogenicity via quantification of the blood cells attached to it during contact with biological solutions. The coated membranes exhibited around 90% reduction in attachment with respect to the uncoated ePTFE for both Gram-positive and Gram-negative strains of bacteria (Staphylococcus aureus and Escherichia coli). The coating was also able to resist blood cell attachment from human whole blood by 81.57% and resist red blood cell attachment from red blood cell concentrate by 93.4%. These ePTFE membranes, which are coated by a simple immersion coating, show significant enhancement of the biocompatibility of the membranes, which shows promise for future use in biological devices.

Early malfunction of a biliary self-expandable metal stent with an antireflux valve: A case report

RATIONALE

Biliary drainage is essential to resolve jaundice in patients with malignant biliary obstruction. Recently, a biliary self-expandable metal stent (SEMS) with an antireflux valve was developed to prevent enteric-biliary reflux. Its antireflux valve was made of expanded polytetrafluoroethylene (ePTFE), a biostable and biocompatible material. Changes of the ePTFE membrane of medical devices are rarely reported in clinical practice.

PATIENT CONCERNS

A 59-year-old woman was admitted with a complaint of jaundice. Around 1 month before, she underwent endoscopic biliary stenting using a SEMS with an antireflux valve.

DIAGNOSIS

Acute cholangitis due to stent clogging was detected on abdominal computed tomography.

INTERVENTIONS

Endoscopic retrograde cholangiopancreatography and removal of the SEMS with deformity were performed.

OUTCOMES

The obstructive jaundice was rapidly resolved after the removal of the clogged stent.

LESSONS

Although the ePTFE membrane is widely used to make medical devices, unexpected changes could occur after the membrane is exposed to bile juice in the duodenum. When performing biliary stenting using a SEMS with an antireflux valve, both the risk of early malfunction and the benefit of the antireflux effect should be considered.

A new simplified technique for artificial chordae implantation in mitral valve repair with its early results

Background

Many techniques in mitral valve repair (MVR) have been reported with successful long-term results. The aim of this study is to present our simplified technique in artificial chordae replacement for MVR, and reporting its short-term outcomes.

Methods

We present a prospective single-surgeon experience. A new simplified artificial chordae implantation technique has been used to repair mitral valves. Postoperative echocardiography at 0, 6, then every 12 months is used to control the results. Endpoints involved freedom from mitral regurgitation (MR), reoperation and major adverse cardiac and cerebrovascular events (MACCE).

Results

Between 01/2016 and 01/2018, 57 consecutive patients undergo MVR using this technique are evaluated. Mean age was 63.6±10.1 years and 68.4% were male. Mitral valve pathology was mainly degenerative (52, 91.2%) or healed endocarditis (5, 8.8%). Besides chordae replacement (3.6±1.1 per patient), annuloplasty was used in all patients to correct annulus dilation and stabilize the repair. Mean cross-clamping time was 53±13.4 minutes in isolated MVR and 69.4±31.1 minutes in concomitant procedures. Postoperative outcomes reported two mortalities. Discharge echocardiography reported mild MR in 4 patients and the rest of patients had non-to trace regurgitation. Follow-up results within a mean of 19.3±8.5 months reported no significant MR or need for reoperation and three more (non-valve related) mortalities.

Conclusions

Our simplified technique allows to reduce the number of used chordae and re-correction if needed, which consequently reduces cross-clamping and bypass time especially in endoscopic MVR. Good intraoperative and short-term results are reported. These results are still under investigation to prove long-term stability of the repair.

New Flexible Internal Annular Fixation Rings for Tricuspid Aortic Valves

OBJECTIVES

Although aortic annulus repair has a long history, there are still no ideal devices to control an aortic annulus. We have developed a new method involving the use of an expanded polytetrafluoroethylene graft with the support of a metallic ring holder during implantation from inside an aorta, with no dissection of the surrounding aortic annulus.

METHODS

We used aortic annular rings of 18 to 24 mm made of Gore-Tex tubed grafts (W.L. Gore & Associates, Flagstaff, AZ, USA) and metallic ring holder. After cutting the graft circumferentially to a 5-mm thickness, it was compressed manually to decrease the thickness. Then, a metallic ring holder corresponding to the graft size was inserted into the graft. The metallic ring holder was fixed to the graft with one 4-0 monofilament suture using 6 holes and the side trench on the metallic ring holder. The proper size for the graft was determined, and the appropriate annuloplasty ring was selected. A row of 4-0 double-needle braided sutures with expanded polytetrafluoroethylene spaghettis was sewn from the aortic side into the left ventricular outflow tract with a horizontal mattress stitch. After all sutures around the annulus were placed, they were tied down and the metallic ring holder was removed. The leaflets were repaired if necessary.

RESULTS

A total of 9 patients with tricuspid aortic valve have undergone this procedure since January 2015. The sizes of the aortic annular rings were 20 mm ( n = 3), 22 mm ( n = 5), and 24 mm ( n = 2). Aortic leaflets were repaired in 6 patients (6 central plications). Concomitant procedures were total aortic arch replacement ( n = 2), mitral valve repair ( n = 2), tricuspid valve repair ( n = 1), and coronary artery bypass grafting ( n = 2). There were no hospital deaths and no major morbidities. All patients were checked for mild or less than mild aortic regurgitation during the mean follow-up period of 13 months. Postoperative echocardiograms showed excellent peak pressure gradients compared with preoperative echocardiograms. Postoperative cardiac computed tomography scans were performed in 6 patients. The discrepancies between the ring size used and postoperative annular size were <1-mm diameter in all patients.

CONCLUSIONS

This new flexible ring is easy to use to fix an aortic annulus from the inside. Early results reveal excellent control of aortic regurgitation with the projected annular size. Further investigations are needed to ensure the effectiveness of the ring.

New insertion support device assisted the accurate placement of tunneled cuffed catheter: First experience of 10 cases

INTRODUCTION

The tunneled cuffed catheter is used in hemodialysis patients for whom an arteriovenous fistula or arteriovenous graft is not suitable or for bridging usage of them. Accurate placement of a tunneled cuffed catheter is necessary for safe hemodialysis, but placement is sometimes difficult because of individual body differences. We developed a new device to support accurate placement of the tunneled cuffed catheter. In this study, we report our first clinical experience of the device.

METHODS

We made the device by expanded polytetrafluoroethylene with some special processes. The processes enable it to maintain plasticity and temporary shape in the autoclaved condition. The device is laid on the surface of the patient's body to mark the root of the catheter with a felt-tipped marker before catheterization. That enables us to know the accurate catheter root and tunneled cuffed catheter exit site on the body surface. Ten patients underwent tunneled cuffed catheter insertion according to the marking.

CASE DESCRIPTION

The mean age was 71.3 ± 12.8 years. The tunneled cuffed catheter was safely placed according to the marking in all patients, and all catheter tips were placed in the right atrium. The mean verification tip location difference before and after catheterization was 0.70 ± 0.48 cm. This result indicated that the device could assist in inserting a catheter accurately within an error of 1.18 cm. The tunneled cuffed catheters were patent in all the cases, without replacement and complications until the end of bridging use or during the observation period.

CONCLUSION

Our newly developed insertion support device enhances safety and prevents catheter waste during replacement.

Laparoscopic diaphragmatic hernia repair using expanded polytetrafluoroethylene (ePTFE) for delayed traumatic diaphragmatic hernia

Traumatic diaphragmatic hernia (TDH) is an uncommon surgical problem, and diagnosis is often delayed. However, the mortality from bowel necrosis can reach 80%. Therefore, suspicion is needed and surgery is required to prevent complications. A 50-year-old man was transferred due to abdominal pain and vomiting. Chest X-ray and computed tomography (CT) scan showed herniation of the stomach through the left diaphragm. The patient had fallen down 15 months ago and CT scan at that time revealed a small defect of the diaphragm without herniation. We diagnosed delayed herniation of TDH and the patient underwent laparoscopic repair using an expanded polytetrafluoroethylene (ePTFE) mesh. Recovery was uneventful and the CT scan at 3 months after the operation showed no recurrence. We reported a delayed presenting TDH and considered a laparoscopic approach to be safe and feasible during elective surgery. Moreover, use of an ePTFE mesh for repair of large diaphragmatic hernia was also feasible.

The use of expanded polytetrafluoroethylene in depressed deformities of the face

Expanded polytetrafluoroethylene (ePTFE) has been extensively used for facial soft tissue augmentation procedures, and is regarded as safe and reliable and suitable as a permanent implant. This implant is generally used in the lower third of the face for lips filling, nasal augmentation, nasolabial folds and chin augmentation, and rarely for congenital or acquired depressed deformities of the face. The aim of the present study was to assess the effects of ePTFE in congenital or acquired depressed deformities of the face. From September, 2008 to January, 2014, 26 patients were implanted with the material ePTFE to correct depressed deformities of the face. The average age at operation was 23.2 years, with a range of 17-45 years. The depressed deformities were lateralized. The follow-up period was 6-18 months (average 9 months). The etiologies of the depressed deformities included stable hemifacial atrophy (3 cases), craniofacial microsomia (13 cases), bony depression after trauma (8 cases), and other unclear reasons (2 cases). The operations were performed under local anesthesia. ePTFE was inserted in different tissue planes that varied among the different subanatomical areas in the face: beneath the superficial temporal fascia in the temporal area, and on the surface of the superficial musculoaponeurotic system in the zygomatic area, cheek and mandibular area. All of the patients were followed up. Most of the patients [25 of 26 patients (96.2%)] were satisfied with the results, while 1 patient (3.8%) was not satisfied for incomplete correction of the depressed deformity. In conclusion, aside from lipofilling and a free flap transfer, the results showed that ePTFE was an alternative treatment for facial depressed deformity.

Milestones of Asian Rhinoplasty

The field of plastic surgery originally developed out of the necessity to reconstruct the human body after the destruction of war. However, injured soldiers were not the only people who desired a change in appearance. After World War II, many people in Asian countries sought to attain a more Western look through surgery. Along with eyes, the nose was the main focus for these cosmetic procedures. In this article, the authors examine the evolution of Asian rhinoplasty from its original description in 1964 to the present. The characteristic anatomical differences between the Western and Asian nose are identified in relation to the technical challenges for rhinoplasty surgeons. Then the benefits and risks of the two major surgical approaches, autograft versus alloplast, are detailed. Finally, the coevolution of techniques and implant usage is traced from a dorsum-only implant, to an L-shaped implant, a cartilaginous cap graft with a one-piece rhinoplasty, an I-shaped implant, and a two-piece augmentation rhinoplasty. Outlining these changes demonstrates the advancement of the field of plastic surgery and the growing expectations of the patient. These advancements have provided the tools necessary to better align a patient's aesthetic goals and their unique anatomical presentation with a specific surgical approach.

Infected ptosis surgery - a rare complication from a multidrug-resistant organism

A 7-year-old boy had a case of congenital ptosis of the right eye and has undergone frontalis sling surgery using Gore-tex material. There was no intraoperative or immediate postoperative complication. However, the patient defaulted his follow-up and presented with right eye preseptal abscess secondary to infected surgical wound 1 month after surgery. He was treated with multiple antibiotics and underwent repeated incision and drainage procedures. However, there was still no resolution of the right eye preseptal abscess. The patient’s condition subsequently improved after removal of the Gore-tex material and treatment with an antibiotic combination of ceftazidime and amikacin. Microbiological analysis finally isolated the multidrug resistant Acinetobacter species. At 6 months follow-up, his right upper eyelid was healed with scarring, but without ptosis.

The biomechanical effects of polytetrafluoroethylene suture augmentations in lateral-row rotator cuff repairs in an ovine model

BACKGROUND

This study investigated the biomechanical effects of expanded polytetrafluoroethylene (ePTFE) suture augmentation patches in rotator cuff repair constructs.

METHODS

The infraspinatus tendon in 24 cadaveric ovine shoulders was repaired using an inverted horizontal mattress suture with 2 knotless bone anchors (ArthroCare, Austin, TX, USA) in a lateral-row configuration. Four different repair groups (6 per group) were created: (1) standard repair using inverted horizontal mattress sutures, (2) repair with ePTFE suture augmentations on the bursal side of the tendon, (3) repair with ePTFE suture augmentations on the articular side, and, (4) repair with ePTFE suture augmentations on both sides of the tendon. Footprint contact pressure, stiffness, and the load to failure of the repair constructs were measured.

RESULTS

Repairs with ePTFE suture augmentations on the bursal side exerted significantly more footprint contact pressure (0.40 ± 0.01 MPa) than those on the articular side (0.34 ± 0.02 MPa, P = .04) and those on both sides (0.33 ± 0.02 MPa, P = .01). At 15 degrees of abduction, ePTFE-augmented repairs on the bursal side had higher footprint contact pressure (0.26 ± 0.03 MPa) compared with standard repairs (0.15 ± 0.02 MPa, P = .01) and with ePTFE-augmented repairs on the articular side (0.18 ± 0.02 MPa, P = .03). The ePTFE-augmented repairs on the bursal side demonstrated significantly higher failure loads (178 ± 18 N) than standard repairs (120 ± 17 N, P = .04).

CONCLUSIONS

Inverted horizontal mattress sutures augmented with ePTFE patches on the bursal side of the tendon enhanced footprint contact pressures and the ultimate load to failure of lateral-row rotator cuff repairs in an ovine model.

Percutaneous metallic stent placement in patients with cancer recurrence at bilioenterostomy site

PURPOSE

To investigate the outcomes of percutaneous metallic stent placement in patients with malignant bilioenterostomy obstruction and to assess the risk factors influencing stent patency.

MATERIALS AND METHODS

From August 2008 to January 2012, 53 patients with malignant bilioenterostomy obstructions were treated with percutaneous placement of biliary metallic stents; this included expanded polytetrafluoroethylene (ePTFE)-covered stent placement in 36 patients and uncovered stent placement in 17 patients.

RESULTS

A total of 75 stents were successfully placed in 53 patients. No major complications occurred in any patients, and minor complications occurred in nine patients (17%). The mean serum bilirubin level, which was 3.6 mg/dL ± 0.7 before drainage, decreased significantly to 2.5 mg/dL ± 0.4 at 1 month after stent placement (P = .041). Successful internal drainage was achieved in 44 of the 53 patients (83%). Kaplan-Meier analysis showed a median overall survival time of 145 days (95% confidence interval, 100-190 d), a median stent patency time of 313 days (95% confidence interval, 46-580 d), and cumulative stent patency rates at 1, 3, 6, 9, and 12 months of 91%, 75%, 64%, 56%, and 45%, respectively. Multivariate Cox regression analysis showed that the use of uncovered stents (odds ratio, 2.924; P = .033) was the only significant independent factor associated with stent occlusion.

CONCLUSIONS

Percutaneous metallic stent placement is a safe and effective method for the treatment of patients with malignant bilioenterostomy obstruction. Moreover, as uncovered stent placement is the only significant independent factor associated with stent occlusion, ePTFE-covered stent placement is preferable in these patients.

Peripheral arterial aneurysms: open or endovascular surgery?

Peripheral arterial aneurysms are uncommon; for some aneurysm types, data are limited to case reports and small case series. There is no Level A evidence in most cases to determine the choice between open or endovascular intervention. The evolution of endovascular technology has vastly improved the armamentarium available to the vascular surgeon and interventionalists in the management of these rare and unusual aneurysms. The choice of operative approach will ultimately be determined on an individual basis, dependent on the patient risk factors, and aneurysm anatomy. After consideration, some aneurysms (femoral, subclavian, carotid and ECAA) fare better with an open first approach; renal, splenic and some visceral artery aneurysms do better with an endovascular first approach. In our practice PAAs are treated with an endovascular first approach. For these rare conditions, both open and endovascular therapy will continue to work in harmony to enhance and extend the capabilities of modern surgical management.

Laparoscopic cholecystectomy delayed by complicated myocardial infarction with papillary muscle rupture, and performed after unique complex mitral repair

A 65-year-old woman was admitted for laparoscopic cholecystectomy, a method of choice for gallbladder diseases. Symptoms of gallstones are similar to angina pectoris, especially in right coronary artery stenosis. In this case, masked by known symptomatic gallstones, unsuspected coronary artery disease manifested with complicated myocardial infarction and pulmonary edema. The patient survived the acute period, treated pharmacologically. Severe mitral insufficiency caused mainly by ruptured papillary muscle, with left ventricle and atrium enlargement, and right coronary artery stenosis were indications for heart surgery. Repair of this infrequent complication of myocardial infarction is rarely feasible. The complex repair, unique for this cause, is described. During the operation, the head of the ruptured posteromedial papillary muscle was re-implanted, and two neo-chords implanted for prolapsing the A2 mitral valve segment. Annuloplasty with a 29 mm elastic ring accomplished repair. Saphenous bypass graft was applied to the only feasible postero-lateral branch. Although intraoperative echocardiography revealed excellent results, inotropic support, and intra-aortic counterpulsation were necessary for weaning off cardio-pulmonary bypass and low cardiac output treatment. The patient was discharged home on postoperative day 12, with anticoagulant administered for 3 months. As soon as it was no longer required, she underwent laparoscopic cholecystectomy, with no complications. Durable results of both operations performed 5 years ago are confirmed by physical examination and ultrasonography. Complex mitral valve repair, rather than valve replacement, should be considered in similar cases. Possibility of coexistence of coronary artery disease should be considered before cholecystectomy. Good quality repair of cardiac disease allows for laparoscopic cholecystectomy.

Treatment of contact dermatitis associated with spinal cord stimulator pulse generator--technical note

BACKGROUND

Expanded polytetrafluoroethylene sheets have been successfully used as a biologic barrier in the treatment of pacemaker contact dermatitis.

TECHNIQUE

In this report, we describe two patients with contact dermatitis related to the implantable pulse generator of a spinal cord stimulator who were treated with expanded polytetrafluoroethylene as a barrier.

RESULTS

Resolution of the dermatitis was achieved in both cases.

CONCLUSIONS

This technique is an effective way of treating contact dermatitis related to implantable pulse generators, without the need for explantation of the neuromodulation system.

Biomimetic fluorocarbon surfactant polymers reduce platelet adhesion on PTFE/ePTFE surfaces

We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0-75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts.