An above-knee femoropopliteal bypass graft constructed of great saphenous vein became dilated in ... more An above-knee femoropopliteal bypass graft constructed of great saphenous vein became dilated in 2 patients 12 and 25 years after surgery. Both patients had several concomitant disorders. The dilations were treated by insertion of an expanded polytetrafluoroethylene-covered nitinol endoprosthesis. There were no major procedural complications. One minor endoleak that developed immediately after endograft placement resolved within 6 weeks. The leg swelling subsided, and the endoprostheses have remained patent for 18 and 24 months, respectively. To our knowledge, these were the first cases in which an endoprosthesis was used to treat dilation of a venous bypass graft.
Journal of applied biomaterials : an official journal of the Society for Biomaterials, 1991
Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, sm... more Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate-polylysine-alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl 2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. This study describes the mutual relationshi...
The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is th... more The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is the preferable site for transplantation of immunoisolated islets. In this study we investigated the minimum islet graft volume needed to restore normoglycemia after free intraperitoneal isogenic transplantation in streptozotocin diabetic rats. Furthermore, graft function was tested by measuring glucose and insulin response to an intravenous glucose load and spontaneously ingested carbohydrate-rich meal. Three graft volumes were used: 8.0-10.0 (group A); 4.0-5.0 (group B); and 2.0-2.3 microliters (group C); 1 microliter contained about 300 islets. All 10 rats in group A and 7 out of 9 rats in group B became normoglycemic for at least 6 months posttransplant, with blood glucose levels not significantly different from normal control animals. Only 3 out of 9 animals in group C became normoglycemic and never for longer than 3 months. The insulin responses to IVGTT in group A and group B were proportional to the grafted islet volume and always significantly lower than those of normal control rats. The insulin response to the test meal showed a similar tendency, which was found to be associated with the absence of preabsorptive insulin secretion. Maximum postprandial blood glucose levels in group A and group B were 0.8 and 1.5 mM higher than in normal control rats. We conclude that intraperitoneal transplantation of at least 4.0-5.0-microliters islet tissue is needed to reverse blood glucose in streptozotocin diabetic rats, and that glucose and insulin levels on IVGTT and test meal in rats with islet grafts of 8.0-10.0 microliters are not completely normalized. It is suggested that the impaired glucose tolerance is due to an insufficient beta-cell mass and a lack of parasympathetic innervation of the transplanted islet tissue.
This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated isle... more This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated islets is influenced by (1) the presence of islet tissue, (2) MHC incompatibility between donor and recipient, or (3) the presence of autoimmune diabetes. Encapsulated Albino Oxford (AO, n = 6, isografts) and Lewis (n = 6, allografts) rat islets, and encapsulated human islets (n = 5, xenografts) were implanted intraperitoneally into streptozotocin-diabetic AO rats. Also, encapsulated AO islets were implanted into autoimmune diabetic Bio Breeding/Organon (BB/O) rats (n = 5, allografts). Five isografts, five allografts, and three xenografts in AO recipients and five allografts in BB/O recipients resulted in normoglycemia. Two weeks after implantation, islets containing capsules were retrieved by peritoneal lavage, after which all animals that had become normoglycemic after transplantation returned to a state of hyperglycemia. Recovery rates of the capsules of these successful grafts, expressed as percentages of the initially implanted graft volume, varied from 72% +/- 7% to 80% +/- 9%. The associated pericapsular infiltrates (PCI) were similar in all groups and varied from 3.2% +/- 1.4% to 8.3% +/- 2.6%. Similar recovery rates and PCI were also found with empty capsules. However, the recovery rates of recipients with graft failures were lower and showed more PCI. Immunohistological staining of PCI showed no differences in the types of cells in the PCI on capsules with or without islets. We conclude that this early PCI is a capsule-induced foreign body reaction that is not influenced by MHC incompatibility or by the presence of autoimmune diabetes, and it should be avoided by improving the biocompatibility of the capsules.
Endografts represent a relatively new treatment modality for occlusive disease of the superficial... more Endografts represent a relatively new treatment modality for occlusive disease of the superficial femoral artery, with promising results. However, endografts may occlude collateral arteries, which may affect outcome in case of failure. The purpose of this study was to analyze the clinical outcome of failed endografts in patients with superficial femoral artery occlusive disease. All patients treated with one or more polytetrafluorethylene-covered stents between November 2001 and December 2011 were prospectively included in a database. Patients with a failure of the endograft were retrospectively analyzed. Clinical and hemodynamic parameters were assessed before the initial procedure and at the time of failure. Outcome of secondary procedures was analyzed. Among the 341 patients who were treated during the study period, 49 (14.4%) failed during follow-up. Mean (standard deviation) Rutherford category at failure did not differ from the category as scored before the initial procedure (3.1 [1.3] vs 3.3 [0.6]; P = .33). Forty-three percent of patients (n = 21) presented with the same Rutherford category as before the initial procedure, 37% (n = 18) with an improved category, and 20% (n = 10) with a deteriorated category. The ankle-brachial index was significantly lower at the time of failure (0.66 [0.19] vs 0.45 [0.19[; P <.002). Seventy-six percent of patients with a failure needed secondary surgery, of which 25% were below knee. The 1-year primary, primary-assisted, and secondary patency rates of secondary bypasses were 55.1%, 62.3%, and 77.7%, respectively. The amputation rate was 4.1% (n = 2). Failure of endografts is not associated with a deterioration in clinical state and is related to a low amputation rate. The hypothesis that covered stents do not affect options for secondary reconstructions could not be confirmed, as 25% of patients with a failure underwent a below-knee bypass. Secondary surgical bypasses are correlated with poor patency. The amputation rate after failure is low.
To evaluate the efficacy and outcome of thrombolysis and thrombectomy for thrombosed polytetraflu... more To evaluate the efficacy and outcome of thrombolysis and thrombectomy for thrombosed polytetrafluoroethylene stent-grafts inserted in the superficial femoral artery (SFA) for occlusive disease. A retrospective review was conducted of 79 consecutive patients with a thrombosed SFA endograft between November 2001 and December 2011. Of these, 46 (58%) were treated with thrombolysis (n=40, 87%) or thrombectomy (n=6, 13%) and form the study group (33 men; median age 66.8 years, range 30-80). Median time from stent-graft insertion to thrombosis was 3 months (range 0-53). Thrombolysis was successful in 38 (95%) patients over a mean 24 hours (range 3-48); one patient had failed lysis and another died during lytic treatment. Thrombectomy was successful in all 6 patients. Thrombosis without a causal lesion was significantly more common in occlusions that presented <30 days after insertion (p=0.01). Over a median follow-up of 14 months (range 1-69), reinterventions were performed for restenosis in 12 patients and reocclusion in 14 patients, all within 18 months after thrombolytic treatment. More than a third of patients (16/45) had definitive failures (2/6 from the thrombectomy group); 4 were treated conservatively (no/minor symptoms) and 12 had bypass grafts. Three (7%) patients eventually required a major amputation. The primary, assisted primary, and secondary patency rates of thrombolysis at 6 months were 56%, 56%, and 68%, respectively. Secondary patency for the entire cohort was 58% at 1 year. Thrombolysis and thrombectomy of thrombosed endografts in the SFA is effective and safe. Patency rates after treatment are moderate, but prolonged secondary patency can be achieved.
We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced ... more We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced insulin secretion by rat islets. Applying the encapsulation method originally described by Lim, we found severely reduced in vitro insulin release (expressed as picomoles of insulin.10 islets-1.45 min-1 when incubated in 16.5 mM glucose), because the insulin release with encapsulated islets was 1.42 +/- 0.49 compared to 13.58 +/- 0.80 with free control islets. This could not be explained by inadequate permeability of the capsule, because insulin release was also severely reduced (2.12 +/- 0.61) when islets were subjected to the procedure but without the membrane-forming polylysine step. Therefore, islets were tested after having been subjected separately to each of the steps of the procedure. Insulin release was not affected by either alginate or CaCl2 but was severely reduced after prolonged suspension in saline or treatment with citrate. When saline and citrate were replaced by Ca2(+)-free Krebs-Ringer bicarbonate buffer (KRBB) and 1 mM EGTA, respectively, insulin release improved significantly both with complete and with incomplete (no polylysine step) encapsulation. This outcome was verified in a set of experiments run in parallel with islets derived from the same isolation procedure. Insulin release was 1.20 +/- 0.23 from islets encapsulated with the method of Lim and 10.73 +/- 1.04 from free control islets. With the modified procedure, insulin release was 9.17 +/- 0.52 vs. 9.61 +/- 1.27 for complete versus incomplete encapsulation, respectively. We conclude that Ca2(+)-free KRBB instead of saline and EGTA instead of citrate should be used to obtain an adequate insulin response from encapsulated islets and that the capsule membrane as such has no influence on glucose and insulin diffusion.
Objectives. Groin wounds following vascular surgery are highly susceptible to healing disturbance... more Objectives. Groin wounds following vascular surgery are highly susceptible to healing disturbances, with reported site infections reaching 30%. Negative pressure incision management systems (NPIMS) are believed to positively influence the prevention of surgical wound-healing disturbances (WHD) and surgical site infections (SSI). NPIMS placed directly after closure of the surgical wound is thought to result in fewer infections; we analysed its effect on postoperative wound infections in patients after vascular surgery via the groin. Methods. From May 2012 to March 2013 we included 90 surgical patients; 40 received a NPIMS. All patients with WHDs were labelled and subanalysed for surgical site infection in case of positive microbiological culture. These infections were graded according to Szilagyi. Number of WHDs and SSIs were compared across cohorts. Results. Patient and perioperative characteristics were equal, except for a significantly higher number of emergency procedures among non-NPIMS patients. We found no significant differences in number of WHDs, SSIs, or Szilagyi grades between the two cohorts. Conclusion. The equal number of SSIs across cohorts showed that NPIMS could not reduce the number of surgical site infections after vascular groin surgery.
In this report, we describe a patient with adventitial cystic disease of the popliteal artery, in... more In this report, we describe a patient with adventitial cystic disease of the popliteal artery, in which direct communication via a duct-like structure between the cystic lesion and the knee-joint synovium resulted in recurrent episodes of intermittent claudication and complete symptom-free intervals (intermittent claudication intermittence). This unusual observation could shed more light on the debated etiology of the disease. Moreover, it emphasizes the importance of complete excision of the cyst along with the presenting anatomic connection with the knee joint.
An above-knee femoropopliteal bypass graft constructed of great saphenous vein became dilated in ... more An above-knee femoropopliteal bypass graft constructed of great saphenous vein became dilated in 2 patients 12 and 25 years after surgery. Both patients had several concomitant disorders. The dilations were treated by insertion of an expanded polytetrafluoroethylene-covered nitinol endoprosthesis. There were no major procedural complications. One minor endoleak that developed immediately after endograft placement resolved within 6 weeks. The leg swelling subsided, and the endoprostheses have remained patent for 18 and 24 months, respectively. To our knowledge, these were the first cases in which an endoprosthesis was used to treat dilation of a venous bypass graft.
Journal of applied biomaterials : an official journal of the Society for Biomaterials, 1991
Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, sm... more Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate-polylysine-alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl 2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. This study describes the mutual relationshi...
The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is th... more The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is the preferable site for transplantation of immunoisolated islets. In this study we investigated the minimum islet graft volume needed to restore normoglycemia after free intraperitoneal isogenic transplantation in streptozotocin diabetic rats. Furthermore, graft function was tested by measuring glucose and insulin response to an intravenous glucose load and spontaneously ingested carbohydrate-rich meal. Three graft volumes were used: 8.0-10.0 (group A); 4.0-5.0 (group B); and 2.0-2.3 microliters (group C); 1 microliter contained about 300 islets. All 10 rats in group A and 7 out of 9 rats in group B became normoglycemic for at least 6 months posttransplant, with blood glucose levels not significantly different from normal control animals. Only 3 out of 9 animals in group C became normoglycemic and never for longer than 3 months. The insulin responses to IVGTT in group A and group B were proportional to the grafted islet volume and always significantly lower than those of normal control rats. The insulin response to the test meal showed a similar tendency, which was found to be associated with the absence of preabsorptive insulin secretion. Maximum postprandial blood glucose levels in group A and group B were 0.8 and 1.5 mM higher than in normal control rats. We conclude that intraperitoneal transplantation of at least 4.0-5.0-microliters islet tissue is needed to reverse blood glucose in streptozotocin diabetic rats, and that glucose and insulin levels on IVGTT and test meal in rats with islet grafts of 8.0-10.0 microliters are not completely normalized. It is suggested that the impaired glucose tolerance is due to an insufficient beta-cell mass and a lack of parasympathetic innervation of the transplanted islet tissue.
This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated isle... more This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated islets is influenced by (1) the presence of islet tissue, (2) MHC incompatibility between donor and recipient, or (3) the presence of autoimmune diabetes. Encapsulated Albino Oxford (AO, n = 6, isografts) and Lewis (n = 6, allografts) rat islets, and encapsulated human islets (n = 5, xenografts) were implanted intraperitoneally into streptozotocin-diabetic AO rats. Also, encapsulated AO islets were implanted into autoimmune diabetic Bio Breeding/Organon (BB/O) rats (n = 5, allografts). Five isografts, five allografts, and three xenografts in AO recipients and five allografts in BB/O recipients resulted in normoglycemia. Two weeks after implantation, islets containing capsules were retrieved by peritoneal lavage, after which all animals that had become normoglycemic after transplantation returned to a state of hyperglycemia. Recovery rates of the capsules of these successful grafts, expressed as percentages of the initially implanted graft volume, varied from 72% +/- 7% to 80% +/- 9%. The associated pericapsular infiltrates (PCI) were similar in all groups and varied from 3.2% +/- 1.4% to 8.3% +/- 2.6%. Similar recovery rates and PCI were also found with empty capsules. However, the recovery rates of recipients with graft failures were lower and showed more PCI. Immunohistological staining of PCI showed no differences in the types of cells in the PCI on capsules with or without islets. We conclude that this early PCI is a capsule-induced foreign body reaction that is not influenced by MHC incompatibility or by the presence of autoimmune diabetes, and it should be avoided by improving the biocompatibility of the capsules.
Endografts represent a relatively new treatment modality for occlusive disease of the superficial... more Endografts represent a relatively new treatment modality for occlusive disease of the superficial femoral artery, with promising results. However, endografts may occlude collateral arteries, which may affect outcome in case of failure. The purpose of this study was to analyze the clinical outcome of failed endografts in patients with superficial femoral artery occlusive disease. All patients treated with one or more polytetrafluorethylene-covered stents between November 2001 and December 2011 were prospectively included in a database. Patients with a failure of the endograft were retrospectively analyzed. Clinical and hemodynamic parameters were assessed before the initial procedure and at the time of failure. Outcome of secondary procedures was analyzed. Among the 341 patients who were treated during the study period, 49 (14.4%) failed during follow-up. Mean (standard deviation) Rutherford category at failure did not differ from the category as scored before the initial procedure (3.1 [1.3] vs 3.3 [0.6]; P = .33). Forty-three percent of patients (n = 21) presented with the same Rutherford category as before the initial procedure, 37% (n = 18) with an improved category, and 20% (n = 10) with a deteriorated category. The ankle-brachial index was significantly lower at the time of failure (0.66 [0.19] vs 0.45 [0.19[; P <.002). Seventy-six percent of patients with a failure needed secondary surgery, of which 25% were below knee. The 1-year primary, primary-assisted, and secondary patency rates of secondary bypasses were 55.1%, 62.3%, and 77.7%, respectively. The amputation rate was 4.1% (n = 2). Failure of endografts is not associated with a deterioration in clinical state and is related to a low amputation rate. The hypothesis that covered stents do not affect options for secondary reconstructions could not be confirmed, as 25% of patients with a failure underwent a below-knee bypass. Secondary surgical bypasses are correlated with poor patency. The amputation rate after failure is low.
To evaluate the efficacy and outcome of thrombolysis and thrombectomy for thrombosed polytetraflu... more To evaluate the efficacy and outcome of thrombolysis and thrombectomy for thrombosed polytetrafluoroethylene stent-grafts inserted in the superficial femoral artery (SFA) for occlusive disease. A retrospective review was conducted of 79 consecutive patients with a thrombosed SFA endograft between November 2001 and December 2011. Of these, 46 (58%) were treated with thrombolysis (n=40, 87%) or thrombectomy (n=6, 13%) and form the study group (33 men; median age 66.8 years, range 30-80). Median time from stent-graft insertion to thrombosis was 3 months (range 0-53). Thrombolysis was successful in 38 (95%) patients over a mean 24 hours (range 3-48); one patient had failed lysis and another died during lytic treatment. Thrombectomy was successful in all 6 patients. Thrombosis without a causal lesion was significantly more common in occlusions that presented <30 days after insertion (p=0.01). Over a median follow-up of 14 months (range 1-69), reinterventions were performed for restenosis in 12 patients and reocclusion in 14 patients, all within 18 months after thrombolytic treatment. More than a third of patients (16/45) had definitive failures (2/6 from the thrombectomy group); 4 were treated conservatively (no/minor symptoms) and 12 had bypass grafts. Three (7%) patients eventually required a major amputation. The primary, assisted primary, and secondary patency rates of thrombolysis at 6 months were 56%, 56%, and 68%, respectively. Secondary patency for the entire cohort was 58% at 1 year. Thrombolysis and thrombectomy of thrombosed endografts in the SFA is effective and safe. Patency rates after treatment are moderate, but prolonged secondary patency can be achieved.
We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced ... more We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced insulin secretion by rat islets. Applying the encapsulation method originally described by Lim, we found severely reduced in vitro insulin release (expressed as picomoles of insulin.10 islets-1.45 min-1 when incubated in 16.5 mM glucose), because the insulin release with encapsulated islets was 1.42 +/- 0.49 compared to 13.58 +/- 0.80 with free control islets. This could not be explained by inadequate permeability of the capsule, because insulin release was also severely reduced (2.12 +/- 0.61) when islets were subjected to the procedure but without the membrane-forming polylysine step. Therefore, islets were tested after having been subjected separately to each of the steps of the procedure. Insulin release was not affected by either alginate or CaCl2 but was severely reduced after prolonged suspension in saline or treatment with citrate. When saline and citrate were replaced by Ca2(+)-free Krebs-Ringer bicarbonate buffer (KRBB) and 1 mM EGTA, respectively, insulin release improved significantly both with complete and with incomplete (no polylysine step) encapsulation. This outcome was verified in a set of experiments run in parallel with islets derived from the same isolation procedure. Insulin release was 1.20 +/- 0.23 from islets encapsulated with the method of Lim and 10.73 +/- 1.04 from free control islets. With the modified procedure, insulin release was 9.17 +/- 0.52 vs. 9.61 +/- 1.27 for complete versus incomplete encapsulation, respectively. We conclude that Ca2(+)-free KRBB instead of saline and EGTA instead of citrate should be used to obtain an adequate insulin response from encapsulated islets and that the capsule membrane as such has no influence on glucose and insulin diffusion.
Objectives. Groin wounds following vascular surgery are highly susceptible to healing disturbance... more Objectives. Groin wounds following vascular surgery are highly susceptible to healing disturbances, with reported site infections reaching 30%. Negative pressure incision management systems (NPIMS) are believed to positively influence the prevention of surgical wound-healing disturbances (WHD) and surgical site infections (SSI). NPIMS placed directly after closure of the surgical wound is thought to result in fewer infections; we analysed its effect on postoperative wound infections in patients after vascular surgery via the groin. Methods. From May 2012 to March 2013 we included 90 surgical patients; 40 received a NPIMS. All patients with WHDs were labelled and subanalysed for surgical site infection in case of positive microbiological culture. These infections were graded according to Szilagyi. Number of WHDs and SSIs were compared across cohorts. Results. Patient and perioperative characteristics were equal, except for a significantly higher number of emergency procedures among non-NPIMS patients. We found no significant differences in number of WHDs, SSIs, or Szilagyi grades between the two cohorts. Conclusion. The equal number of SSIs across cohorts showed that NPIMS could not reduce the number of surgical site infections after vascular groin surgery.
In this report, we describe a patient with adventitial cystic disease of the popliteal artery, in... more In this report, we describe a patient with adventitial cystic disease of the popliteal artery, in which direct communication via a duct-like structure between the cystic lesion and the knee-joint synovium resulted in recurrent episodes of intermittent claudication and complete symptom-free intervals (intermittent claudication intermittence). This unusual observation could shed more light on the debated etiology of the disease. Moreover, it emphasizes the importance of complete excision of the cyst along with the presenting anatomic connection with the knee joint.
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Papers by Wilbert Fritschy