Fresh Arterial Grafts as Conduits for Vascular Reconstructions in Transplanted Patients

Renal artery infectious (mycotic) pseudoaneurysms in renal transplantation recipients

INTRODUCTION

Infection of the artery at or around the anastomotic site is an ominous complication commonly presenting as a leak and/or local dissolution of the arterial wall.

MATERIAL AND METHODS

Narrative review based on relevant PubMed, EMBASE, and Scielo indexed English or Spanish-written articles for the period January 2000-December 2019. A pooled analysis regarding etiology was performed. Based on the results obtained with this approach, a diagnostic/therapeutic algorithm is suggested in order to optimize its clinical management.

FINDINGS

Arterial pseudoaneurysms are pseudocapsuled contained hematomas generated as the result of an arterial leaking. They are infrequent (<1% of cases), mostly related with infection (contamination of preservation fluid or sepsis) and located at the arterial anastomotic site in renal transplantation recipients. Although they are frequently diagnosed in symptomatic patients days/weeks after transplantation, they may remain unnoticed for long periods being diagnosed incidentally. Color coded-Doppler ultrasound confirms the clinical suspicion. Angio CT-scan and angiography are used for surgical planning or endovascular treatment, respectively. The etiological diagnosis is made on a basis of excised tissue culture. The decision-making process regarding the treatment approach, mostly relies on clinical presentation and anatomical location. Therapeutic options include ultrasound-guided percutaneous thrombin injection, endovascular treatment, and surgery.

CONCLUSIONS

Mycotic pseudoaneurysms in renal transplantation recipients may pose a significant challenge in cases of spontaneous rupture, given the risk for massive bleeding and death. Adequate management requires accurate diagnosis. Early endovascular stenting remains the treatment of choice in hemodynamically unstable patients. Percutaneous injection and vascular reconstruction present variable success rates in preserving graft function.

Renal artery infectious (mycotic) pseudoaneurysms in renal transplantation recipients

INTRODUCTION

Infection of the artery at or around the anastomotic site is an ominous complication commonly presenting as a leak and/or local dissolution of the arterial wall.

MATERIAL AND METHODS

Narrative review based on relevant PubMed, EMBASE, and Scielo indexed English or Spanish-written articles for the period January 2000-December 2019. A pooled analysis regarding etiology was performed. Based on the results obtained with this approach, a diagnostic/therapeutic algorithm is suggested in order to optimize its clinical management.

FINDINGS

Arterial pseudoaneurysms are pseudocapsuled contained hematomas generated as the result of an arterial leaking. They are infrequent(<1% of cases),mostly related with infection(contamination of preservation fluid or sepsis) and located at the arterial anastomotic site in renal transplantation recipients. Although they are frequently diagnosed in symptomatic patients days/weeks after transplantation, they may remain unnoticed for long periods being diagnosed incidentally. Color coded-Doppler ultrasound confirms the clinical suspicion. Angio CT-scan and angiography are used for surgical planning or endovascular treatment, respectively. The etiological diagnosis is made on a basis of excised tissue culture. The decision-making process regarding the treatment approach, mostly relies on clinical presentation and anatomical location. Therapeutic options include ultrasound-guided percutaneous thrombin injection, endovascular treatment, and surgery.

CONCLUSIONS

Mycotic pseudoaneurysms in renal transplantation recipients may pose a significant challenge in cases of spontaneous rupture, given the risk for massive bleeding and death. Adequate management requires accurate diagnosis. Early endovascular stenting remains the treatment of choice in hemodynamically unstable patients. Percutaneous injection and vascular reconstruction present variable success rates in preserving graft function.

Organization model for allotransplantations of cryopreserved vascular grafts in Czech Republic

The transplantation of fresh or cryopreserved vascular allografts in patients with a prosthetic graft infection or critical limb ischemia is necessary for their limb salvage and, in many cases, represents a lifesaving procedure. While transplantation of fresh allografts has a long history in the Czech Republic, the standard use of cryopreserved vascular allografts was introduced into the clinical practice in 2011 as a result of the implementation of EU Directive 2004/23/EC into national legislation (Human Cell and Tissue Act No. 296/2008 Coll.). The authors present an organizational model based on cooperation between the majority of Czech Transplant Centers with a tissue establishment licensed by the national competent authority. In various points, we are addressing individual aspects of experimental and clinical studies which affect clinical practice. Based on experimental and clinical work, the first validation of cryopreserved arterial and venous grafts for clinical use was performed between 2011 and 2013. The growing number of centers participating in this programme led to a growing number of patients who underwent transplantation of vascular allografts. In 2015 the numbers of transplanted fresh versus cryopreserved allografts in the Czech Republic were almost equal. Cooperation of the participating centers in the Czech Republic with the licensed Tissue Establishment made it possible to achieve a full compliance with the European Union Directives, and harmonized national legal norms and assured a high quality of cryopreserved vascular allografts.

Anastomotic pseudoaneurysm complicating renal transplantation: treatment options

INTRODUCTION

Anastomotic pseudoaneurysm following renal transplantation is uncommon. Indications for repair, treatment options and outcomes remain controversial.

REPORT

We present 6 renal transplant recipients with large anastomotic pseudoaneurysms. Five of the patients underwent open repair while one had a stent-grafting and delayed transplant nephrectomy for a ruptured pseudoaneurysm. A transplant nephrectomy was needed in all cases but one. Arterial reconstruction enabled limb salvage in all cases. One patient died of sepsis postoperatively. No patient presented late infection, failure of vascular reconstruction, nor pseudoaneurysm recurrence.

CONCLUSIONS

Surgical excision of anastomotic pseudoaneurysms results in high rates of allograft loss. Less invasive techniques have a place in selected cases.

Cold-stored Venous Allografts in the Treatment of Critical Limb Ischaemia

OBJECTIVES

To assess the outcome of cold-stored venous allografts in critically ischemic limbs in patients with no ipsilateral autogenous greater saphenous vein.

DESIGN

A non-randomised, retrospective, single-center study.

METHODS

From September 2000 to June 2006, 46 cold-stored venous allografts obtained during multiorgan harvest were implanted into 44 critically ischaemic limbs of 43 patients. The indication for reconstructions was rest pain (24%) or tissue lost (76%). Sixty-seven percent of procedures were performed as secondary reconstructions, and 61% of veins were anastomosed to tibial or pedal arteries. Thirty-seven percent of patients received prednisone, and 46% tacrolimus as postoperative immunosuppressive therapy. Mean patient follow-up period was 13.3 months (range 1 week to 60 months).

RESULTS

The secondary patency rate for the cohort was 83+/-5.6% at 1 month, 64+/-8.2% at 6 months, 57+/-10.0% at 12 months and 46+/-10.7% at 24 months. Limb salvage rate was 96+/-3.1% at 1 month, 78+/-6.9% at 6 months, 71+/-8.1% at 12 months and 50+/-11.8% at 24 months.

CONCLUSION

Cold-stored venous allografts are an alternative conduit for limb salvage procedures when ipsilateral autogenous vein is unavailable.

Delayed administration of FK 506 is sufficient to suppress acute rejection changes after aortal transplantation in rats

Arterial allografts are used now-a-days as a modality in the treatment of vascular prosthesis infections. Prolonged administration of immunosuppressive drugs seemed to be essential for long-time patency rates of alloarterial vascular reconstructions. Nevertheless, the use of immunosuppressives if there exist an acute infection is controversial. The experimental work described herein studied effects of a delayed low-dose FK 506 administration on the development of acute rejection changes 30 days after aortal transplantation in rats. The response of the recipient's immune system to aortal wall antigens of the donor in the field of no immunosuppression resulted in an intimal proliferation and its infiltration by immunocompetent cells of the recipient, necrosis of medial smooth muscle cells, including deposition of immunoglobulins, and a massive adventitial infiltration of CD4 and CD8 positive cells. On the other hand, all the principal histological signs of rejection listed above were suppressed by FK 506 administration, no matter whether the immunosuppressive was administered on day 0 or day 7 after the transplantation.