Long-term results of autologous scaffold-free tissue-engineered vascular graft for hemodialysis access.

BACKGROUND: The growing size of the end stage renal disease (ESRD) population highlights the need for effective dialysis access. Exhausted native vascular access options have led to increased use of catheters and prosthetic shunts, which are both associated with high risks of access failure and infection. Emerging alternatives include tissue-engineered vascular grafts (TEVG). Here we present the endpoint results for 10 ESRD patients with the scaffold-free tissue-engineered vascular access produced from sheets of extracellular matrix produced in vitro by human cells in culture. METHODS: Grafts were implanted as arteriovenous shunts in 10 ESRD patients with a complex history of access failure. Follow-up included ultrasound control of graft morphology and function, dialysis efficiency, access failure, intervention rate, as well as immunohistochemical analysis of graft structure. RESULTS: One patient died of unrelated causes and three shunts failed to become useable access grafts during the 3-month maturation phase. The 12-month primary and secondary patency for the other six shunts was 86%. Survival of six shunts functioning as the vascular access was 22 ± 12 months with longest primary patency of 38.6 months. The dialysis event rate of 3.34 per patient-year decreased significantly with the use of this TEVG to 0.67. CONCLUSIONS: This living autologous tissue-engineered vascular graft seems to be an alternative to synthetic vascular access options, exhibiting advantages of native arteriovenous fistula.

New biological solutions for hemodialysis access.

Since Scribner described the first prosthetic chronic dialysis shunt in 1961, the surgical techniques and strategies to maintain vascular access have improved dramatically. Today, hundreds of thousands of patients worldwide are treated with some combination of native vein fistula, synthetic vascular graft, or synthetic semipermanent catheter. Despite significantly lower efficacy compared with autologous fistulae, the basic materials used for synthetic shunts and catheters have evolved surprisingly slowly. The disparity between efficacy rates and concomitant maintenance costs has driven a strong campaign to decrease the use of synthetic grafts and catheters in favor of native fistulae. Whether arguing the benefits of Fistula First or "Catheter Last," the fact that clinicians are in need of an alternative to expanded polytetrafluoroethylene (ePTFE) is irrefutable. The poor performance of synthetic materials has a significant economic impact as well. End-stage renal disease (ESRD) accounts for approximately 6% of Medicare's overall budget, despite a prevalence of about 0.17%. Of that, 15%-25% is spent on access maintenance, making hemodialysis access a critical priority for Medicare. This clinical and economic situation has spawned an aggressive effort to improve clinical care strategies to reduce overall cost and complications. While the bulk of this effort has historically focused on developing new synthetic biomaterials, more recently, investigators have developed a variety of cell-based strategies to create tissue-engineered vascular grafts. In this article, we review the evolution of the field of cardiovascular tissue engineering. We also present an update on the Lifeline™ vascular graft, an autologous, biological, and tissue-engineered vascular graft, which was the first tissue-engineered graft to be used clinically in dialysis patients.

Desvascularización preoperatoria de tumor del glomus mediante colocación de stent cubierto en la carótida externa / Preoperative Devascularization of a Glomus Tumor with a Covered Stent in the External Carotid Artery

Los tumores del glomus carotídeo se caracterizan por su vascularización importante y su manejo preoperatorio puede incluir la embolización percutánea previa a la resección quirúrgica. Esta técnica disminuye la hemorragia y el tamaño del tumor y hace menos riesgosa la disección, con reducción de la morbimortalidad. Una técnica alternativa es la interrupción de la irrigación del tumor mediante la colocación de un stent cubierto en la carótida externa, que es la vía principal de irrigación. Esta técnica es útil en especial en tumores grandes y evita el riesgo de embolia intracraneal cuando se emplean coils para realizar la embolización. En esta presentación se describe el caso de una paciente de 31 años tratada de esta manera; se le colocó el stent y 24 horas después se realizó la resección del tumor.

Glomus tumors are hypervascularized neoplasms which may require preoperative percutaneous embolization. This technique reduces the incidence of bleeding, the tumor size, the risk of resection-related complications, and morbidity and mortality. The interruption of the tumor blood supply placing a covered stent in the external carotid artery, the main tumor-supplying vessel, is an alternative option. This technique is especially useful in large tumors and prevents the risk of intracranial embolism when coils are used during embolization. We describe the case of a 31 year-old female patient who underwent stent placement 48 hours before tumor resection.

Hypogastric artery stenosis in a patient with severe chronic ischemia.

Atherosclerotic lesions of the hypogastric artery have been recognized as a cause of buttock claudication, thigh claudication, and impotence, and usually treated by endovascular procedures and in some instances with open surgery. We report an unusual case of a total occlusion of the left external iliac artery, severe stenosis of the left hypogastric artery with rest pain, and ischemic lesion in the left foot that was successfully treated with hypogastric angioplasty and covered self-expanding stent implant. The patient recovered distal pulses, rest pain disappeared, and the ischemic lesion healed; currently the patient walks without intermittent claudication, and the lesion of the toe has healed.

Effectiveness of haemodialysis access with an autologous tissue-engineered vascular graft: a multicentre cohort study.

BACKGROUND: Application of a tissue-engineered vascular graft for small-diameter vascular reconstruction has been a long awaited and much anticipated advance for vascular surgery. We report results after a minimum of 6 months of follow-up for the first ten patients implanted with a completely biological and autologous tissue-engineered vascular graft. METHODS: Ten patients with end-stage renal disease who had been receiving haemodialysis through an access graft that had a high probability of failure, and had had at least one previous access failure, were enrolled from centres in Argentina and Poland between September, 2004, and April, 2007. Completely autologous tissue-engineered vascular grafts were grown in culture supplemented with bovine serum, implanted as arteriovenous shunts, and assessed for both mechanical stability during the safety phase (0-3 months) and effectiveness after haemodialysis was started. FINDINGS: Three grafts failed within the safety phase, which is consistent with failure rates expected for this high-risk patient population. One patient was withdrawn from the study because of severe gastrointestinal bleeding shortly before implantation, and another died of unrelated causes during the safety period with a patent graft. The remaining five patients had grafts functioning for haemodialysis 6-20 months after implantation, and a total of 68 patient-months of patency. In these five patients, only one intervention (surgical correction) was needed to maintain secondary patency. Overall, primary patency was maintained in seven (78%) of the remaining nine patients 1 month after implantation and five (60%) of the remaining eight patients 6 months after implantation. INTERPRETATION: Our proportion of primary patency in this high-risk cohort approaches Dialysis Outcomes Quality Initiative objectives (76% of patients 3 months after implantation) for arteriovenous fistulas, averaged across all patient populations.

Mechanical properties of completely autologous human tissue engineered blood vessels compared to human saphenous vein and mammary artery.

We have previously reported the initial clinical feasibility with our small diameter tissue engineered blood vessel (TEBV). Here we present in vitro results of the mechanical properties of the TEBVs of the first 25 patients enrolled in an arterio-venous (A-V) shunt safety trial, and compare these properties with those of risk-matched human vein and artery. TEBV average burst pressures (3490+/-892 mmHg, n=230) were higher than native saphenous vein (SV) (1599+/-877 mmHg, n=7), and not significantly different from native internal mammary artery (IMA) (3196+/-1264 mmHg, n=16). Suture retention strength for the TEBVs (152+/-50 gmf) was also not significantly different than IMA (138+/-50 gmf). Compliance for the TEBVs prior to implantation (3.4+/-1.6%/100 mmHg) was lower than IMA (11.5+/-3.9%/100 mmHg). By 6 months post-implant, the TEBV compliance (8.8+/-4.2%/100 mmHg, n=5) had increased to values comparable to IMA, and showed no evidence of dilation or aneurysm formation. With clinical time points beyond 21 months as an A-V shunt without intervention, the mechanical tests and subsequent lot release criteria reported here would seem appropriate minimum standards for clinical use of tissue engineered vessels.

Revascularizacion renal y recuperacion de la funcion en pacientes en dialisis / Kidney revascularization and recuperation of the function in patients in dialysis

Se realizó una revisión bibliográfica sobre la recuperación de la función con la reperfusión del riñon isquémico en dializados por ese motivo, encontrándose solamente 57 pacientes, número exiguo pues se estima que la nefropatía isquémica es la causa de insuficiencia en el 5 por ciento al 15 por ciento de los dializados, y la posibilidad de revertirla está bien estabelecida. La etiología más frecuente fue la arteriosclerosis; predominó en enfermos mayores de 60 años, con arteriosclerosis en otros territorios, que empeoraron su hipertensión arterial y/o presentaron episodios de induficiencia renal y/o cardíaca aguda, a veces de difícil tratamiento sin la revascularización. Se recuperaron riñoes con tiempos variables de isquemia preoperatoria, (días a 13 meses de diálisis, promedio 30,5 días), con riñones menores de 9 u 8 cm y aun de 7 cm, flujo renal ausente, curvas planas o ausencia de nefrograma en estudios radioisotópicos o sin colaterales ni lecho distal en la arteriografía. La oclusión arterial total fue más frecuente que la estenosis. Treinta y cinco por ciento de los pacientes revascularizados recuperaron la función en forma inmediata, 52 por ciento requirió transitoria, y sólo el 12.2 por ciento no se recuperó. La hipertensión mejoró o se controló con 1 o 2 drogas. Los buenos resultados se mantuvieron durante períodos prolongados. Con una selección clínica adecuada, la revascularización puede mejorar rápidamente la función renal de enfermos dializados por nefropatía isquémica, mejorando substancialmente el pronóstico y la calidad de vida de muchos de ellos.

Revascularizacion renal y recuperacion de la funcion en pacientes en dialisis / Kidney revascularization and recuperation of the function in patients in dialysis

Se realizó una revisión bibliográfica sobre la recuperación de la función con la reperfusión del riñon isquémico en dializados por ese motivo, encontrándose solamente 57 pacientes, número exiguo pues se estima que la nefropatía isquémica es la causa de insuficiencia en el 5 por ciento al 15 por ciento de los dializados, y la posibilidad de revertirla está bien estabelecida. La etiología más frecuente fue la arteriosclerosis; predominó en enfermos mayores de 60 años, con arteriosclerosis en otros territorios, que empeoraron su hipertensión arterial y/o presentaron episodios de induficiencia renal y/o cardíaca aguda, a veces de difícil tratamiento sin la revascularización. Se recuperaron riñoes con tiempos variables de isquemia preoperatoria, (días a 13 meses de diálisis, promedio 30,5 días), con riñones menores de 9 u 8 cm y aun de 7 cm, flujo renal ausente, curvas planas o ausencia de nefrograma en estudios radioisotópicos o sin colaterales ni lecho distal en la arteriografía. La oclusión arterial total fue más frecuente que la estenosis. Treinta y cinco por ciento de los pacientes revascularizados recuperaron la función en forma inmediata, 52 por ciento requirió transitoria, y sólo el 12.2 por ciento no se recuperó. La hipertensión mejoró o se controló con 1 o 2 drogas. Los buenos resultados se mantuvieron durante períodos prolongados. Con una selección clínica adecuada, la revascularización puede mejorar rápidamente la función renal de enfermos dializados por nefropatía isquémica, mejorando substancialmente el pronóstico y la calidad de vida de muchos de ellos. (AU)

Cirugía ambulatoria en patología venosa de los miembros inferiores / Ambulatory surgery in vein pathology of inferior legs

Desde enero de 1990 se efectuaron 60 operaciones por várices de miembros inferiores, 48 se realizaron en forma ambulatoria sin registrarse complicaciones. Se analizan el tipo de operaciones practicadas y la técnica anestésica utilizada. Debido a los resultados logrados durante 1990 la tendencia actual se inclina hacia una selección adecuada para cirugía ambulatoria llegando a un 100%de casos ambulatorios en el primer semestre de 1991

Cirugía ambulatoria en patología venosa de los miembros inferiores / Ambulatory surgery in vein pathology of inferior legs

Desde enero de 1990 se efectuaron 60 operaciones por várices de miembros inferiores, 48 se realizaron en forma ambulatoria sin registrarse complicaciones. Se analizan el tipo de operaciones practicadas y la técnica anestésica utilizada. Debido a los resultados logrados durante 1990 la tendencia actual se inclina hacia una selección adecuada para cirugía ambulatoria llegando a un 100%de casos ambulatorios en el primer semestre de 1991