Comparative assessment of biodegradable-antireflux heparine coated ureteral stent: animal model study.

BACKGROUND: Double J ureteral stents are widely used on urological patients to provide drainage of the upper urinary tract. Unfourtunately, ureteral stents are not free from complications, as bacterial colonization and require a second procedure for removal. The purpose of the current comparative experimental study is to evaluate a new heparin-coated biodegradable antireflux ureteral stent (BraidStent®-H) to prevent urinary bacterial colonization. METHODS: A total of 24 female pigs were underwent determination of bacteriuria and nephrosonographic, endoscopic and contrast fluoroscopy assessment of the urinary tract. Afterward, were randomly assigned animals to Group-I, in which a 5Fr double-pigtail ureteral stent was placed for 6 weeks, or Group-II, in which a BraidStent®-H was placed. Follow-up assessments were performed at 1, 3, 6, 8, 12 weeks. The final follow-up includes the above methods and an exhaustive pathological study of the urinary tract was accomplished after 20 weeks. RESULTS: Bacteriuria findings in the first 48 h were significant between groups at 6 h and 12 h. Asymptomatic bacteriuria does not reach 100% of the animals in Group-II until 48 h versus Group-I where it appears at 6 h. The weekly bacteriuria mean rate was 27.7% and 44.4% in Group I and II respectively, without statistical significance. In Group II there were no animals with vesicoureteral reflux, with statistical significance at 3 and 6 weeks with Group-I. The 91.2% of stents in Group-II were degraded between 3 and 6 weeks, without obstructive fragments. Distal ureteral peristalsis was maintained in 66.6-75% in Group-II at 1-6 weeks. CONCLUSIONS: The heparin coating of BraidStent® allows an early decrease of bacterial colonization, but its effectiveness is low at the long term. Heparin coating did not affect scheduled degradation rate or size of stents fragments. BraidStent®-H avoids the side effects associated with current ureteral stents, thus should cause less discomfort to patients.

Kidney transplant from uncontrolled donation after circulatory death donors maintained by nECMO has long-term outcomes comparable to standard criteria donation after brain death.

Uncontrolled donation after circulatory death (uDCD) increases organ availability for kidney transplant (KT) with short-term outcomes similar to those obtained from donation after brain death (DBD) donors. However, heterogeneous results in the long term have been reported. We compared 10-year outcomes between 237 KT recipients from uDCD donors maintained by normothermic extracorporeal membrane oxygenation (nECMO) and 237 patients undergoing KT from standard criteria DBD donors during the same period at our institution. We further analyzed risk factors for death-censored graft survival in the uDCD group. Delayed graft function (DGF) was more common in the uDCD group (73.4% vs 46.4%; P < .01), although glomerular filtration rates at the end of follow-up were similar in the 2 groups. uDCD and DBD groups had similar rates for 10-year death-censored graft (82.1% vs 80.4%; P = .623) and recipient survival (86.2% vs 87.6%; P = .454). Donor age >50 years was associated with graft loss in the uDCD group (hazard ratio: 1.91; P = .058), whereas the occurrence of DGF showed no significant effect. uDCD KT under nECMO support resulted in similar graft function and long-term outcomes compared with KT from standard criteria DBD donors. Increased donor age could negatively affect graft survival after uDCD donation.

Antireflux ureteral stent proof of concept assessment after minimally invasive treatment of obstructive uropathy in animal model.

OBJECTIVES: To assess the efficacy of a new anti-reflux intraureteral stent design in a swine model after minimally invasive treatment of ureteral stricture to reduce ureteral stent morbidity, previous to manufacture this design in a biodegradable fashion. METHODS: Twenty-eight female pigs were included. The study began with a cystoscopic, nephrosonographic and contrast fluoroscopic assessment. Afterwards, obstructive uropathy model in right ureter was created. Obstruction was confirmed 6 weeks later and animals were randomly distributed into 2 groups. Group I underwent laser endopyelotomy and Group-II laparoscopic pyeloplasty A 3Fr anti-reflux intraureteral stent was placed 6 weeks. Follow-up evaluations were performed at 3-6 weeks. The final follow-up was completed at 5 months and included the aforementioned diagnostic methods and pathological study. RESULTS: None of the study animals showed any vesicoureteral reflux signs or ureteral orifice injury. There were no urinomas or ureteric fistulas. The dislodgement rate was 10.7%. After 6 weeks of stenting, 71.4% of ureters showed ureteral peristalsis below the stent, and 100% at the final follow-up. After pathological assessment, no differences were shown at UPJ and healing in the incised area was correct in both groups. CONCLUSIONS: The new stent design avoids vesicoureteral reflux and bladder trigone irritation, consequently might reduce morbidity associated with double pigtail ureteral stents. This study also shows that it is only necessary temporary scaffolding the incised ureteral segment and not the entire length of the ureter after minimally invasive surgery. It is also necessary to manufacture this design in a biodegradable material, thus avoiding its removal.

Antireflux ureteral stent proof of concept assessment after minimally invasive treatment of obstructive uropathy in animal model / Evaluación preliminar de un catéter ureteral antirreflujo tras el tratamiento minimamente invasivo de la uropatia obstructiva en modelo animal

OBJECTIVES: To assess the efficacy of a new anti-reflux intraureteral stent design in a swine model after minimally invasive treatment of ureteral stricture to reduce ureteral stent morbidity, previous to manufacture this design in a biodegradable fashion. METHODS: Twenty-eight female pigs were included. The study began with a cystoscopic, nephrosonographic and contrast fluoroscopic assessment. Afterwards, obstructive uropathy model in right ureter was created. Obstruction was confirmed 6 weeks later and animals were randomly distributed into 2 groups. Group I underwent laser endopyelotomy and Group-II laparoscopic pyeloplasty A 3Fr anti-reflux intraureteral stent was placed 6 weeks. Follow-up evaluations were performed at 3-6 weeks. The final follow-up was completed at 5 months and included the aforementioned diagnostic methods and pathological study. RESULTS: None of the study animals showed any vesicoureteral reflux signs or ureteral orifice injury. There were no urinomas or ureteric fistulas. The dislodgement rate was 10.7%. After 6 weeks of stenting, 71.4% of ureters showed ureteral peristalsis below the stent, and 100% at the final follow-up. After pathological assessment, no differences were shown at UPJ and healing in the incised area was correct in both groups. CONCLUSIÓN: The new stent design avoids vesicoureteral reflux and bladder trigone irritation, consequently might reduce morbidity associated with double pigtail ureteral stents. This study also shows that it is only necessary temporary scaffolding the incised ureteral segment and not the entire length of the ureter after minimally invasive surgery. It is also necessary to manufacture this design in a biodegradable material, thus avoiding its removal

OBJETIVOS: Evaluar un nuevo diseño de catéter intraureteral-antirreflujo en modelo porcino tras el tratamiento mínimamente invasivo de estenosis ureterales. MÉTODOS: Se emplearon 28 ejemplares de la especie porcina. El estudio se inicia con la evaluación cistoscópica, nefrosonográfica y fluoroscópica de la vía urinaria. Posteriormente, se procede a la creación del modelo de estenosis en el uréter derecho. La obstrucción se confirma 6 semanas después y los animales son distribuidos aleatoriamente en dos grupos homogeneos. El Grupo-I, fue tratado mediante endopielotomía láser, y el Grupo-II mediante una pieloplastia laparoscópica. En ambos grupos se coloca durante 6 semanas, un catéter ureteral antirreflujo de 3Fr. Los seguimientos de los animales del estudio se realizaron a las 3-6 semanas. Con un seguimiento final a los 5 meses, que incluye un estudio anatomopatológico. RESULTADOS: Ninguno de los animales del estudio mostró reflujo vesicoureteral o signos de lesión en el orificio ureteral. No se produjeron ni fístulas ni urinomas. La tasa de migración alcanzó un 10,7%. Tras 6 semanas de cateterización el 71,4% de los uréteres mostraron peristaltismo ureteral distal y un 100% a los 5 meses. Tras el estudio anatomopatológico, no se evidencian diferencias en la zona de la unión pieloureteral y la cicatrización fue correcta en ambos grupos. CONCLUSIONES: El nuevo catéter ureteral impide el reflujo vesicoureteral y la irritación del trígono vesical, por lo que previsiblemente podría reducir la morbilidad asociada a los catéteres ureterales. El estudio también muestra que solo es necesaria la cateterización temporal del segmento incidido y no de todo el uréter. Evidentemente es necesario desarrollar este nuevo diseño en su versión biodegradable, para su empleo clínico futuro

Stents ureterales metálicos. Presente y futuro / Metallic ureteral stents. Present and future

El manejo de las obstrucciones ureterales de origen maligno o de carácter benigno complicado continúa siendo a día de hoy un desafío para la comunidad urológica. En este sentido, el empleo de stents metálicos podría considerarse como una alternativa útil a las técnicas de drenaje convencionales, ya que permiten en un solo acto, la resolución de la obstrucción, sin derivaciones externas y sin los efectos adversos de las derivaciones actuales. Otra importante ventaja que aportan es que no necesitan ser recambiados con la frecuencia que requieren los catéteres doble jota o las sondas de nefrostomía. Desde sus primeras aplicaciones en el tracto urinario superior, hasta la actualidad, el diseño de los stents metálicos ha experimentado una notable evolución. El principal escollo en sus inicios fue el empleo de stents destinados a otros territorios orgánicos, lo que provocaba una alta tasa de fracaso, al no tener en cuenta en su diseño, el ambiente hostil que representa el medio urinario para este tipo de dispositivos, ni la existencia de peristaltismo ureteral. Gracias a los posteriores diseños metálicos (Memokath, Uventa, Allium Medical URS-stent, Resonance), la actual generación de stents metálicos ureterales ha conseguido mejorar la tasa de éxito respecto a los diseños clásicos, adaptándose a la dinámica ureteral y mejorando el recubrimiento y las aleaciones. A pesar de estos avances, hoy en día, su aplicación se ve limitada a pacientes muy seleccionados, debido a la aparición de efectos indeseables asociados a estos stents como son la hiperplasia urotelial obstructiva, la incrustración o la migración. El conocimiento preciso de los mecanismos fisiopatológicos responsables de los citados efectos adversos, junto con la aplicación de la Bioingeniería que permita desarrollar stents metálicos liberadores de fármaco, stents biorrecubiertos, o nuevos materiales metálicos biodegradables que atenúen o disminuyan los efectos de estos, puede ser la clave que permita el desarrollo de un stent metálico ideal

The management of ureteral obstruction of malignant origin or complicated benign obstruction continues to be a challenge for the urological community. In this sense, the use of metallic stents could be considered a useful alternative to the conventional drainage techniques, because it accomplishes the resolution of obstruction in a single procedure, without external diversions and without the adverse effects of current diversions. Another important advantage they offer is that they do not need replacement as frequently as double J catheters or nephrostomy tubes require. From their first applications in the upper urinary tract until now the design of metallic stents has experienced a notable evolution. The main obstacle at the beginning was the use of stents intended for other organic territories, which caused a high rate of failures, since they did not take into consideration in their designs the hostile environment represented by urine for this type of devices, neither the existence of ureteral peristaltism. Thanks to subsequent metallic designs (Memokath, Uventa, Allium Medical URS-stent, Resonance), the current generation of ureteral metallic stents has improved the success rate in comparison to classical designs, accommodating to ureteral dynamics and improving the coating and alloys. Despite these advances, today, their application is limited to very selected patients due to the onset of undesirable effects still associated with theses stents, such as obstructive urothelial hyperplasia, encrustation or migration. The precise knowledge of the physiopathological mechanisms responsible for the cited adverse effects, together with the application of Bioengineering enabling the development of drug eluting metallic stents, biocoated stents, or new biodegradable metallic materials that mitigate or diminish their effects, may be the key to allow the development of the ideal metallic stent

[Effects of preventive double-J stent placement in ureteral obstruction treatment with metal stents on animal model]. / EFECTOS DE LA COLOCACIÓN PREVENTIVA DE UN CATÉTER URETERAL JJ DURANTE EL TRATAMIENTO DE LA OBSTRUCCIÓN URETERAL CON STENTS METÁLICOS EN MODELO ANIMAL.

OBJECTIVES: The purpose of this experimental study is to assess the additive effects of temporary JJ stent placement together with metal stents (MS) in the treatment obstructive uropathy, in order to reduce urothelial hyperplasia formation. METHODS: Twenty-four pigs were included, and an experimental model of obstructive uropathy was created. Six weeks after obstructive uropathy model induction, ureteral obstruction was confirmed using ultrasonography, ureteropyelography and endoluminal ultrasound. Afterwards, animals were randomly distributed into 2 groups. Group I underwent covered MS placement and JJ ureteral stenting for 3 weeks. Animals in Group II received the same MS without simultaneous JJ stenting. The follow-up was at 3 weeks and at 6 months. RESULTS: Incidence of urothelial hyperplasia was higher in Group I than Group II, but without statically significant differences. On the other hand, Group II showed a significantly higher degree of obstruction severity due to hyperplasia. The migration rate in both groups was 33.3% at the end of the study. Significant differences were shown on animals showing urinary tract infection (UTI) and hyperplasia against those with hyperplasia but no infection. There was a high rate of correlation between UTI and obstructive urothelial hyperplasia. CONCLUSIONS: Placement of JJ ureteral catheter does not inhibit urothelial hyperplasia associated with placement of metal mesh stents, although it significantly reduces its obstructive severity in long-term follow-up. Urinary tract infection is directly related to the development and magnitude of the urothelial hyperplasia.

Efectos de la colocación preventiva de un catéter ureteral JJ durante el tratamiento de la obstrucción ureteral con stents metálicos en modelo animal / Effects of preventive double-J stent placement in ureteral obstruction treatment with metal stents on animal model

OBJETIVOS: Evaluar el efecto aditivo de los catéteres JJ temporales conjuntamente al empleo de stents metálicos (SM) ureterales en el tratamiento de la uropatía obstructiva, con el propósito de disminuir la hiperplasia urotelial (HU) asociada a los stents. MÉTODO: Se emplearon 24 ejemplares de la especie porcina, que se sometieron a un modelo de estenosis ureteral. Transcurridas 6 semanas, la obstrucción ureteral fue confirmada mediante ecografía, ureteropielografía y ultrasonografía endoluminal. Posteriormente,los animales fueron distribuidos aleatoriamente en dos grupos homogéneos: Grupo I, donde se dispone un SM recubierto permanente y un catéter JJ durante 3 semanas. En el Grupo II, se libera el mismo tipo de SM sin catéter ureteral JJ. Los seguimientos se realizaron a las 3 semanas y a los 6 meses. RESULTADOS: La incidencia de HU fue mayor en el Grupo I, que en el Grupo II; aunque sin diferencias estadísticamente significativas. Por su parte, el Grupo II muestra significación estadística con respecto al grado de obstrucción ureteral por HU. La tasa de migración del stent metálico es similar entre ambos grupos al final del estudio (33.3%). Se muestran diferencias significativas entre los animales con infección urinaria e hiperplasia frente a los que no presentan infección pero sí hiperplasia. Existe un alto índice de correlación estadística entre la infección urinaria y el carácter obstructivo de la hiperplasia. CONCLUSIONES: La disposición de catéteres ureterales JJ no inhibe la aparición de HU asociada a los SM, sin embargo, sí reduce significativamente su carácter obstructivo a largo plazo. La infección urinaria se relaciona directamente con el desarrollo de HU y con la magnitud de esta

OBJECTIVES: The purpose of this experimental study is to assess the additive effects of temporary JJ stent placement together with metal stents (MS) in the treatment obstructive uropathy, in order to reduce urothelial hyperplasia formation. METHODS: Twenty-four pigs were included, and an experimental model of obstructive uropathy was created. Six weeks after obstructive uropathy model induction, ureteral obstruction was confirmed using ultrasonography, ureteropyelography and endoluminal ultrasound. Afterwards, animals were randomly distributed into 2 groups. Group I underwent covered MS placement and JJ ureteral stenting for 3 weeks. Animals in Group II received the same MS without simultaneous JJ stenting. The follow-up was at 3 weeks and at 6 months. RESULTS: Incidence of urothelial hyperplasia was higher in Group I than Group II, but without statically significant differences. On the other hand, Group II showed a significantly higher degree of obstruction severity due to hyperplasia. The migration rate in both groups was 33.3% at the end of the study. Significant differences were shown on animals showing urinary tract infection (UTI) and hyperplasia against those with hyperplasia but no infection. There was a high rate of correlation between UTI and obstructive urothelial hyperplasia. CONCLUSIONS: Placement of JJ ureteral catheter does not inhibit urothelial hyperplasia associated with placement of metal mesh stents, although it significantly reduces its obstructive severity in long-term follow-up. Urinary tract infection is directly related to the development and magnitude of the urothelial hiperplasia

Evaluation in an animal model of a hybrid covered metallic ureteral stent: a new design.

OBJECTIVE: To evaluate a new design for a hybrid, dynamic, metallic ureteral stent that might avoid the formation of urothelial hyperplasia after ureteral metallic stenting in an experimental study. MATERIALS AND METHODS: A total of 30 healthy female pigs were included in the present study, and an experimental obstructive uropathy in the right lumbar ureter was created in each pig. Obstruction was confirmed using percutaneous ultrasonography and retrograde ureteral pyelography and endoluminal ultrasonography 6 weeks after obstructive uropathy model creation. Then, the pigs were randomly distributed into 2 groups. Group 1 underwent standard metallic ureteral self-expanding internally covered stent deployment. Group 2 received a new hybrid metallic ureteral self-expanding internally covered stent. The follow-up period was 6 months. RESULTS: The hybrid metallic ureteral self-expanding internally covered stent group had a lower rate of urothelial hyperplasia (21% vs 70%), reduced stent migration (6.6% vs 33.3%), and a greater success rate after 6 months of follow-up (86.6% vs 47%) compared with the standard metallic ureteral self-expanding internally covered stent deployment group, with statically significant differences between the 2 groups. CONCLUSION: Our experimental results have indicated that the use of the hybrid metallic ureteral self-expanding internally covered stent in ureteral strictures is feasible, safe, and effective and reduces the formation of urothelial hyperplasia without secondary interventions to maintain ureteral patency.

Donation after cardiac death: results of the SUMMA 112 - Hospital 12 de Octubre Program.

BACKGROUND: In 2005, our center started a donation after cardiac death (DACD) program, by which patients who present an irreversible cardiac arrest outside hospital are brought to our center with the purpose of organ donation. We reviewed the outcomes of our program of kidney transplants from DACD. METHODS: We conducted a retrospective study of the DACD, and we reviewed the procedures carried out in our institution between July 2005 and December 2010 and descriptively analyzed the results obtained for kidney donation. RESULTS: One hundred and fifty-two of 274 potential donors were transferred to our hospital. Of them, 126 (82.8%) were connected to cardiopulmonary bypass machine, and organs were procured in 113 donors (74.3%). The discarded grafts were mainly due to inadequate perfusion. One hundred and fifty-six kidneys were transplanted (51.3%). Over a median follow-up period of 18 ± 13.7 months, the median creatinine clearance was 78.2 ± 10.2 ml/min. 8.6% of the grafts had no primary function, and 85% had a delayed graft function. Recipient survival and graft survival were 98% and 87%, respectively. CONCLUSIONS: DACD is an adequate source of organs for kidney transplantation. Our functional and survival results are encouraged in the short term, although further work is required to increase the program's benefits.

New combined approach in metallic ureteral stenting to avoid urothelial hyperplasia: study in swine model.

PURPOSE: We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure. MATERIALS AND METHODS: We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 × 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation. RESULTS: At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2. CONCLUSIONS: Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.

Ureteral double-J wire stent effectiveness after endopyelotomy: an animal model study.

OBJECTIVES: The aim of this experimental study was to assess the possibility of decreasing the size of the ureteral stents used after an endopyelotomy. To this end, an experimental study was performed which compared a ureteral double-J wire stent versus a standard 7F ureteral stent after endopyelotomy. METHODS: Twenty healthy female pigs were randomly divided into 2 groups: group I (double pigtail ureteral stent 7F) and group II (lumenless ureteral double-J wire stent, Zebrastent™, 0.035 inches in diameter). Percutaneous, endoluminal ultrasonographic and fluoroscopic studies were analyzed during the 3 different phases of the study. The first phase included premodel documentation of normal urinary tracts and laparoscopic ureteropelvic junction (UPJ) obstruction induction. During the second phase, 6 weeks later, diagnosis and endopyelotomy were carried out. Sixteen weeks after the obstruction treatment, follow-up imaging studies and postmortem evaluations of all animals were performed. RESULTS: After the sonographic and fluoroscopic assessments, we determined the success rate for each group: 80% for group I and 90% for group II. No significant statistical differences were evident in the evolution of the diameter of the UPJ between groups. Better healing of the UPJ and a lower level of retroperitoneal repercussions were seen in group II. CONCLUSIONS: The ureteral double-J wire stent (Zebrastent) has been shown to be highly effective after endopyelotomy. This means that it is possible to reduce the size of ureteral stents after endopyelotomy with the advantages that this entails. Double-J ureteral stents probably act as a scaffold rather than a mold.