Vascular graft thrombosis after pancreas transplantation: comparison of the FK 506 and cyclosporine eras

Pancreas transplantation: a single-institution experience in Japan

Purpose

We herein report our experience with pancreas transplantation in 26 patients at a single institution in Japan between August 2001 and December 2011.

Methods

We reviewed the medical records of 26 pancreas transplantations performed in our institute.

Results

The early complications (within 2 weeks) included one graft venous thrombosis, one arterial thrombosis, and two reoperations for bleeding. Of the 26 pancreas transplant recipients, five lost pancreas graft function. Of 24 simultaneous pancreas–kidney recipients, three lost kidney graft function due to noncompliance. The patient, pancreas, and kidney survival rates were 100, 96 and 93 % at 1 year; 100, 80 and 93 % at 5 years; and 100, 67 and 68 % at 10 years, respectively. Of all these complications, venous thrombosis after pancreas transplantation was the most critical.

Conclusions

As the largest series of pancreas transplantations in a single institution in Japan, our series yielded better results than the worldwide data recorded by the International Pancreas Transplant Registry. Routine postoperative anticoagulation therapy is not necessary for the prevention of graft thrombosis if sufficient fluid infusion is strictly controlled and the graft blood flow is frequently monitored. When graft thrombosis occurs, both early detection and appropriate intervention are extremely important if the pancreas graft is to survive.

Long term follow-up of the endovascular trans-vessel wall technique for parenchymal access in rabbit with full clinical integration

Objective

Endovascular techniques are providing options to surgical/percutaneous cell transplantation methods. Some cells, e.g. insulin producing cells, are not suitable for intra-luminal transplantation and for such cells, other options must be found. We have constructed a “nanocatheter” with a penetrating tip for vessel perforation, thereby creating a working channel for parenchymal access by endovascular technique. To finish the procedure safely, the distal tip is detached to provide a securing plug in the vessel wall defect.

Materials and Methods

We have performed interventions with full clinical integration in the superior mesenteric artery (SMA), the subclavian artery and the external carotid artery in rabbits. No hemorrhagic- or thromboembolic events occurred during the procedure. Stenosis formation and distal embolisation were analyzed by angiography and macroscopic inspection during autopsy at five, 30 and 80 days. All animals and implanted devices were also evaluated by micro-dissections and histochemical analysis.

Results

In this study we show safety data on the trans-vessel wall technique by behavioral, angiographical and histological analysis. No stenosis formation was observed at any of the follow-up time points. No animals or organs have shown any signs of distress due to the intervention. Histological examination showed no signs of hemorrhage, excellent biocompatibility with no inflammation and a very limited fibrous capsule formation around the device, comparable to titanium implants. Further, no histological changes were detected in the endothelia of the vessels subject to intervention.

Conclusions

The trans-vessel wall technique can be applied for e.g. cell transplantations, local substance administration and tissue sampling with low risk for complications during the procedure and low risk for hemorrhage, stenosis development or adverse tissue reactions with an 80 days follow-up time. The benefit should be greatest in organs that are difficult or risky to reach with surgical techniques, such as the pancreas, the CNS and the heart.

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Pancreas Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5-10% have been diagnosed with type 1 diabetes mellitus (TIDM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age. The effects of T1DM can be devastating, as the disease often leads to significant secondary complications, morbidity, and decreased quality of life. Since the late 1960s, surgical treatment for diabetes mellitus has continued to evolve and has become a viable alternative to chronic insulin administration. In this review, the historical evolution, current status, graft efficacy, benefits, and complications of pancreas transplantation are explored.

Complications after pancreas transplantation

PURPOSE OF REVIEW

The history of transplantation of the pancreas, unlike that of transplantation of other abdominal organs, has largely been shaped by the associated surgical complications. After more than three decades of progress, surgical-technical pancreas graft failure rates have decreased to approximately 8%. The most recent developments in this area are systematically reviewed in this article.

RECENT FINDINGS

Vascular graft thrombosis remains, by far, the most common cause of technical graft failure. Recent reports suggested that pancreas preservation with histidine-tryptophan-ketoglutarate solution (HTK) might be a risk factor for reperfusion pancreatitis, graft thrombosis and decreased short- and long-term graft survival. It remains unclear whether these results are, at least in part, related to HTK flush volumes and extended preservation (e.g.,>12 h). For selected thrombosed pancreas grafts, there has been renewed interest in pharmacological, interventional, and surgical salvage. For selected recipients with early pancreas graft thrombosis not amenable to a salvage intervention, transplant pancreatectomy in conjunction with immediate retransplantation has emerged as a viable option. For graft thrombosis prevention, the enhanced backtable pancreas vascular reconstruction techniques (e.g., gastroduodenal artery revascularization) proposed by some authors await more formal study. For prevention of native vascular complications in high-risk recipients, several technical modifications have been reported. Developments with respect to other surgical complications (wound infection, pancreatitis, leak, and bleeding) have been more incremental.

CONCLUSION

Recent evidence underscores the importance of judicious donor and recipient selection and of optimization of preservation and surgical factors for excellent short- and long-term pancreas transplant outcomes.

Do inherited hypercoagulable states play a role in thrombotic events affecting kidney/pancreas transplant recipients?

BACKGROUND

Pancreas graft thrombosis remains the leading non-immunologic cause of graft loss after pancreas transplantation. We studied the role of hypercoagulable states (HCS) in pancreas graft thrombosis (pthx).

METHODS

Between January 1, 1994, and January 1, 2003, 131 pancreas transplant recipients experienced a pthx (n = 67) or other thrombotic events. Fifty-six recipients consented to have their blood drawn and tested for the HCS. These results were compared with a control group of pancreas transplant recipients who did not experience a thrombotic event. Fisher's exact test was used to compare the groups.

RESULTS

We found 18% of the recipients with pancreas thrombosis to have a HCS. Factor V Leiden (FVL) was found in 15% vs. 4% in the control group (p = ns) vs. 3-5% in the general white population. We found 3% of the pancreas thrombosis patients to have a prothrombin gene mutation (PGM) vs. 0% in the control group (p = ns) vs. 1-2% in the general white population.

CONCLUSIONS

Of pancreas transplant recipients with thrombosis, 18% had one or more of the most common factors associated with a HCS (FVL or PGM). This can be compared with 4% in a control group and 4-7% in the general white population, respectively. Although the differences are not statistically significant due to small numbers, we feel that the findings may be clinically relevant. While this is only a pilot study, it may be reasonable to screen select pancreas transplant candidates for HCS, especially FVL and PGM, until more data become available.

Intraabdominal Bleeding Following Simultaneous Pancreas-Kidney Transplantation Treated With Angiographic Embolization

Significant early bleeding is one of the surgical complications following simultaneous pancreas-kidney transplantation that has historically shaped the procedure. The consequence, exploratory laparotomy, carries high morbidity levels and elevated costs for the health system. Angiographic intervention is already a common procedure for the treatment of late, but not early, vascular complications. We describe a case of an early vascular complication that was successfully treated with angiographic embolization in a to simultaneous pancreas-kidney transplant patient.

Surveillance and rescue of pancreas grafts

BACKGROUND

Technical failure rates are higher for pancreas allografts (PA) compared with other solid organs. Posttransplant surveillance and prompt availability of rescue teams with multidisciplinary expertise both contribute to improve this result. We herein report a single institution's experience with posttransplant surveillance and rescue of PA.

METHODS

A retrospective survey was performed of a consecutive series of 177 whole organ pancreas transplants in 173 patients. Antithrombotic prophylaxis was used in all recipients and tailored on anticipated individual risk of thrombosis. During the first posttransplant week, all PA were monitored with daily Doppler ultrasonography. Surgical complications were defined as all adverse events requiring relaparotomy during the initial hospital stay or the first 3 posttransplant months.

RESULTS

A total of 26 relaparotomies were performed in 25 patients (14.7%). One recipient needed two relaparotomies (0.6%). Graft rescue was attempted in patients without permanent parenchymal damage at repeat surgery and in 12 recipients diagnosed with nonocclusive vascular thrombosis. Overall 25 grafts (96.3%) were rescued and one was lost. One-year recipient and graft survivals in patients with versus without complications potentially leading to allograft loss were 92.6% and 63.0% versus 94.4% and 94.3%, respectively. Excluding complications for which graft rescue was not possible, 1-year graft survival rate increased to 78.7%.

CONCLUSIONS

Close posttransplant surveillance can allow rescue of a relevant proportion of PA developing nonocclusive venous thrombosis or other surgical complications. Further improvement awaits better understanding of biological reasons for posttransplant complications jeopardizing PA survival and the development of more effective preventive measures.

Opções técnicas utilizadas no transplante pancreático em centros brasileiros

OBJETIVO: Analisar o perfil dos principais centros de transplantes do Brasil, quanto às opções técnicas no transplante de pâncreas. MÉTODO: Foi encaminhado um questionário por correio eletrônico (email) para um membro de cada equipe de 12 centros de transplante do Brasil, com casuística mínima de um transplante de pâncreas. O questionário continha 10 perguntas, abordando aspectos controversos e não padronizados. RESULTADOS: A maioria dos centros (90,9%) utiliza incisão mediana. O órgão de escolha a ser implantado primeiro foi principalmente o rim, em 63% dos centros. Em relação à drenagem venosa, 90,9% utilizam a drenagem sistêmica. A ligadura da veia ilíaca interna é realizada em 54,5% dos centros. A maioria dos centros (90,9%) utiliza a drenagem entérica para transplante combinado pâncreas-rim. Para o transplante de pâncreas isolado, apenas cinco centros responderam, sendo que dois utilizam a drenagem entérica e três a vesical. A utilização de dreno na cavidade abdominal ocorre em 63% dos centros. Em 72,7% dos centros é realizada algum tipo de indução na imunossupressão para o transplante combinado pâncreas-rim, sendo a imunossupressão básica a associação de tacrolimus (FK506), micofenolato mofetil (MMF) e corticóide. A antibioticoprofilaxia é realizada por todos os centros e profilaxia para fungos é realizada por seis centros (54,5%). Oito centros (72,7%) utilizam algum tipo de profilaxia para trombose vascular, em esquemas diversos. CONCLUSÃO: Existem diversos caminhos técnicos na condução do transplante pancreático. A falta de padronização dificulta a análise e a comparação dos resultados. Apesar dessa heterogeneidade das equipes, observamos uma tendência para a realização de incisão mediana, drenagem venosa sistêmica e exócrina entérica, com a utilização de algum tipo de profilaxia para trombose vascular nos transplantes combinados pâncreas-rim.

Technical failures after pancreas transplants: why grafts fail and the risk factors--a multivariate analysis

BACKGROUND

Technical failure (TF) rates remain high after pancreas transplants; while rates have decreased over the last decade, more than 10% of all pancreas grafts continue to be lost due to technical reasons. We performed a multivariate analysis to determine causes and risk factors for TF of pancreas grafts.

RESULTS

Between 1994 and 2003, 937 pancreas transplants were performed at our center in the following transplant categories: simultaneous pancreas-kidney (SPK) (n=327), pancreas after kidney (PAK) (n=399), and pancreas transplant alone (PTA) (n=211). Of these, 123 (13.1%) grafts were lost due to technical reasons (thrombosis, leaks, infections). TF rates were higher for SPK (15.3%) versus PAK (12.2%) or PTA (11.4%), though this was not statistically significant. Thrombosis accounted for 52.0% of all TFs. Other causes were infections (18.7%), pancreatitis (20.3%), leaks (6.5%), and bleeding (2.4%). Thrombosis was the most common cause for TF in all three transplant categories. By multivariate analysis, the following were significant risk factors for TF of the graft: recipient body mass index (BMI) >30 kg/m (relative risk [RR]=2.42, P=0.0003), preservation time >24 hr (1.87, P=0.04), cause of donor death other than trauma (RR=1.58, P=0.04), enteric versus bladder drainage (1.68, P=0.06), and donor BMI >30 kg/m (1.66, P=0.06). Not significant were donor or recipient age, a retransplant, and the category of transplant.

CONCLUSIONS

TFs remain significant after pancreas transplants. In SPK recipients, TF represents the most common cause of pancreas graft loss. For isolated pancreas transplants, TF is second only to rejection as a cause of graft loss. Increased preservation times and donor or recipient obesity seem to be risk factors. Minimizing these risks factors would be important to try to decrease TF.

The impact of donor obesity on outcomes after cadaver pancreas transplants

We examined the impact of donor obesity on surgical complications and graft function after pancreas transplants. From January 1994 through December 2001, we performed 711 cadaver pancreas transplants. We analyzed outcomes for three groups based on donor body mass index (BMI): <25 kg/m2 (n=434), 25-30 (n=196), and >30 (n=81). Donor characteristics were similar between the three groups except for donor cause of death. Cerebrovascular deaths were more common in the BMI >30 group (p=0.002), while trauma deaths were more common in the BMI <25 group (p=0.02). In the BMI >30 group, surgical complications, most notably surgical infections and thrombosis, were significantly more common; in addition, technical failure rates were higher and short-term graft survival was inferior. The incidence of technical failure was 9.7% in the BMI <25 group, 16.3% in the BMI 25-30 group, and 21.0% in the BMI >30 group (p=0.04). However, when we looked at only technically successful transplants, we found minimal differences in the three groups with regard to graft survival at 1 and 3 years posttransplant. Donor obesity increased the incidence of surgical complications in our pancreas recipients, but did not affect initial graft function posttransplant. Technically successful transplants using obese donors results in good graft function at 1 and 3 years posttransplant.

Kidney retransplants after initial graft loss to vascular thrombosis

BACKGROUND

Vascular thrombosis early after a kidney transplant is an infrequent but devastating complication. Often, no cause is found. These recipients are generally felt to be good candidates for a retransplant. However, their ideal care at the time of the retransplant and their outcomes have not been well documented. We studied outcomes in 16 retransplant recipients who had lost their first graft early posttransplant (< 1 month) to vascular thrombosis.

METHODS

Of 2,003 kidney transplants between I January 1984 and 30 September 1998, we identified 32 recipients who had lost their first graft early posttransplant to vascular thrombosis. Of these 32 recipients, 16 were subsequently retransplanted and detailed chart reviews were done.

RESULTS

Of the 16 retransplant recipients, 12 lost their first graft to renal vein thrombosis and 4 to renal artery thrombosis. Thrombosis generally occurred early (mean, 3.6 d). Five recipients underwent a complete hematologic workup to rule out a thrombophilic disorder before their retransplant: 4 had a positive result (presence of antiphospholipid antibodies, n = 3; increased homocysteine levels, n = 1). These 4 recipients, along with 1 other recipient who had a strong family history of thrombosis, underwent thrombosis prophylaxis at the time of their retransplant. Prophylaxis consisted of low-dose heparin for the first 3-5 d posttransplant, followed by acetylsalicylic acid or Coumadin. Of the 16 retransplant recipients, none developed thrombosis. Of the 5 who underwent thrombosis prophylaxis, none had significant bleeding complications. At a mean follow-up of 5.4 yr, 10 (63%) recipients have functioning grafts. Causes of graft loss in the remaining 6 recipients were death with function (n = 5, 31%) and acute rejection (n = 1.6%). Graft and patient survival rates after these 16 retransplants were equivalent to results after primary transplants. The incidence of acute and chronic rejection was also no different (p = ns).

CONCLUSION

Vascular thrombosis in the absence of obvious technical factors should prompt a workup for a thrombophilic disorder before a retransplant. Recipients with an identified disorder should undergo prophylaxis at the time of the retransplant. Results in these retransplant recipients are equivalent to those seen in primary transplant recipients.

Surgical risks and outcome of pancreas retransplants

BACKGROUND

The increased popularity of pancreas transplants has led to an increased number of potential candidates for retransplants after the initial graft has been lost to technical failure or rejection. We studied a group of recipients who underwent pancreas transplants at a single center to determine whether retransplant recipients were at higher risk of complications.

METHODS

Between June 1, 1994, and Dec 31, 1997, a total of 213 pancreas transplants were performed at the University of Minnesota. Of these, 187 were primary transplants and 26 were retransplants. Demographically, the two groups were not significantly different. We analyzed and compared the two groups with respect to incidence of surgical complications, graft survival rates, and patient survival rates.

RESULTS

Surgical complications such as bleeding and vascular thrombosis were slightly more common after retransplants, but this trend did not quite reach statistical significance. Infectious complications and leaks were equivalent between the two groups. The incidence of acute rejection was higher after retransplants (P =.02). At 3 years posttransplant, patient survival was no different between the two groups, but pancreas graft survival was lower after retransplants (P =.08). The incidence of early graft loss (by 6 months posttransplant) was significantly higher in retransplant recipients (27% vs 14%, P =.04).

CONCLUSIONS

Pancreas retransplants can be performed with a minimal increase in surgical complications. However, graft survival after retransplants is slightly inferior to that after primary transplants, probably for both immunologic and nonimmunologic reasons. Retransplants can be offered to suitable candidates, but they may require more aggressive monitoring for rejection.