Anticoagulation in simultaneous pancreas kidney transplantation - On what basis?

BACKGROUND: Despite technical refinements, early pancreas graft loss due to thrombosis continues to occur. Conventional coagulation tests (CCT) do not detect hypercoagulability and hence the hypercoagulable state due to diabetes is left untreated. Thromboelastogram (TEG) is an in-vitro diagnostic test which is used in liver transplantation, and in various intensive care settings to guide anticoagulation. TEG is better than CCT because it is dynamic and provides a global hemostatic profile including fibrinolysis. AIM: To compare the outcomes between TEG and CCT (prothrombin time, activated partial thromboplastin time and international normalized ratio) directed anticoagulation in simultaneous pancreas and kidney (SPK) transplant recipients. METHODS: A single center retrospective analysis comparing the outcomes between TEG and CCT-directed anticoagulation in SPK recipients, who were matched for donor age and graft type (donors after brainstem death and donors after circulatory death). Anticoagulation consisted of intravenous (IV) heparin titrated up to a maximum of 500 IU/h based on CCT in conjunction with various clinical parameters or directed by TEG results. Graft loss due to thrombosis, anticoagulation related bleeding, radiological incidence of partial thrombi in the pancreas graft, thrombus resolution rate after anticoagulation dose escalation, length of the hospital stays and, 1-year pancreas and kidney graft survival between the two groups were compared. RESULTS: Seventeen patients who received TEG-directed anticoagulation were compared against 51 contemporaneous SPK recipients (ratio of 1: 3) who were anticoagulated based on CCT. No graft losses occurred in the TEG group, whereas 11 grafts (7 pancreases and 4 kidneys) were lost due to thrombosis in the CCT group (P = 0.06, Fisher's exact test). The overall incidence of anticoagulation related bleeding (hematoma/ gastrointestinal bleeding/ hematuria/ nose bleeding/ re-exploration for bleeding/ post-operative blood transfusion) was 17.65% in the TEG group and 45.10% in the CCT group (P = 0.05, Fisher's exact test). The incidence of radiologically confirmed partial thrombus in pancreas allograft was 41.18% in the TEG and 25.50% in the CCT group (P = 0.23, Fisher's exact test). All recipients with partial thrombi detected in computed tomography (CT) scan had an anticoagulation dose escalation. The thrombus resolution rates in subsequent scan were 85.71% and 63.64% in the TEG group vs the CCT group (P = 0.59, Fisher's exact test). The TEG group had reduced blood product usage {10 packed red blood cell (PRBC) and 2 fresh frozen plasma (FFP)} compared to the CCT group (71 PRBC/ 10 FFP/ 2 cryoprecipitate and 2 platelets). The proportion of patients requiring transfusion in the TEG group was 17.65% vs 39.25% in the CCT group (P = 0.14, Fisher's exact test). The median length of hospital stay was 18 days in the TEG group vs 31 days in the CCT group (P = 0.03, Mann Whitney test). The 1-year pancreas graft survival was 100% in the TEG group vs 82.35% in the CCT group (P = 0.07, log rank test) and, the 1-year kidney graft survival was 100% in the TEG group vs 92.15% in the CCT group (P = 0.23, log tank test). CONCLUSION: TEG is a promising tool in guiding judicious use of anticoagulation with concomitant prevention of graft loss due to thrombosis, and reduces the length of hospital stay.

Heterogeneity in the nonplanarity and arterial curvature of arteriovenous fistulas in vivo.

OBJECTIVE: Native arteriovenous fistulas (AVFs) for hemodialysis are susceptible to nonmaturation. Adverse features of local blood flow have been implicated in the formation of perianastomotic neointimal hyperplasia that may underpin nonmaturation. Whereas computational fluid dynamic simulations of idealized models highlight the importance of geometry on fluid and vessel wall interactions, little is known in vivo about AVF geometry and its role in adverse clinical outcomes. This study set out to examine the three-dimensional geometry of native AVFs and the geometric correlates of AVF failure. METHODS: As part of an observational study between 2013 and 2016, patients underwent creation of an upper limb AVF according to current surgical best practice. Phase-contrast magnetic resonance imaging was performed on the day of surgery to obtain luminal geometry along with ultrasound measurements of flow. Magnetic resonance imaging data sets were segmented and reconstructed for quantitative and qualitative analysis of local geometry. Clinical maturation was evaluated at 6 weeks. RESULTS: There were 60 patients who were successfully imaged on the day of surgery. Radiocephalic (n = 17), brachiocephalic (n = 40), and brachiobasilic (n = 3) fistulas were included in the study. Centerlines extracted from segmented vessel lumen exhibited significant heterogeneity in arterial nonplanarity and curvature. Furthermore, these features are more marked in brachiocephalic than in radiocephalic fistulas. Across the cohort, the projected bifurcation angle was 73 ± 16 degrees (mean ± standard deviation). Geometry was preserved at 2 weeks in 20 patients who underwent repeated imaging. A greater degree of arterial nonplanarity (log odds ratio [logOR], 0.95 per 0.1/vessel diameter; 95% confidence interval [CI], 0.22-1.90; P = .03) and a larger bifurcation angle (logOR, 0.05 per degree; 95% CI, 0.01-0.09; P = .02) are associated with a greater rate of maturation, as is fistula location (upper vs lower arm; logOR, -1.9; 95% CI, -3.2 to 0.7; P = .002). CONCLUSIONS: There is significant heterogeneity in the three-dimensional geometry of AVFs, in particular, arterial nonplanarity and curvature. In this largest cohort of AVF geometry to date, the effect of individual geometric correlates on maturation is uncertain but supports the premise that future modeling studies will need to acknowledge the complex geometry of AVFs.

Vascular access in lipoprotein apheresis: a retrospective analysis from the UK's largest lipoprotein apheresis centre.

INTRODUCTION: Lipoprotein apheresis (LA) has proven to be an effective, safe and life-saving therapy. Vascular access is needed to facilitate this treatment but has recognised complications. Despite consistency in treatment indication and duration there are no guidelines in place. The aim of this study is to characterise vascular access practice at the UK's largest LA centre and forward suggestions for future approaches. METHODS: A retrospective analysis of vascular access strategies was undertaken in all patients who received LA treatment in the low-density lipoprotein (LDL) Apheresis Unit at Harefield Hospital (Middlesex, UK) from November 2000 to March 2016. RESULTS: Fifty-three former and current patients underwent 4260 LA treatments. Peripheral vein cannulation represented 79% of initial vascular access strategies with arteriovenous (AV) fistula use accounting for 15%. Last used method of vascular access was peripheral vein cannulation in 57% versus AV fistula in 32%. Total AV fistula failure rate was 37%. CONCLUSIONS: Peripheral vein cannulation remains the most common method to facilitate LA. Practice trends indicate a move towards AV fistula creation; the favoured approach receiving support from the expert body in this area. AV fistula failure rate is high and of great concern, therefore we suggest the implementation of upper limb ultrasound vascular mapping in all patients who meet treatment eligibility criteria. We encourage close ties between apheresis units and specialist surgical centres to facilitate patient counselling and monitoring. Further prospective data regarding fistula failure is needed in this expanding treatment field.

Investigation and treatment of a complicated inflammatory aortoiliac aneurysm.

Inflammatory abdominal aortic aneurysms (IAAAs) account for 5% to 10% of all abdominal aortic aneurysms, occurring primarily in males. Their true etiology is unknown. Symptoms and signs of IAAA are so variable that they present to a wide range of specialties. There is debate in the literature whether IAAA is a manifestation of systemic autoimmune disease. We describe the case of a young female patient with complicated inflammatory aortoiliac aneurysmal disease, illustrating diagnostic and treatment challenges that remain. Our patient had a positive autoantibody screen, raised erythrocyte sedimentation rate, positive enzyme-linked immunosorbent spot test, and saccular aneurysms, including infective and inflammatory etiologies in her differential diagnosis. Early diagnosis is crucial to limit disease progression, morbidity, and mortality. Medical management is important to address the underlying disease process, but a combination of endovascular and open surgical intervention is often necessary for definitive treatment. Available evidence offers plausibility for benefit of endovascular intervention over open repair.

Live donor kidney transplantation: attitudes of patients and health care professionals concerning the pre-surgical pathway and post-surgical follow-up.

OBJECTIVES: We surveyed the following groups of individuals concerning their attitudes towards the pathway leading up to live donor kidney transplantation (LDKT) and post-operative follow-up: kidney transplant (deceased and live donor) recipients, live kidney donors and medical and nursing staff caring for end-stage renal disease and dialysis patients. MATERIALS AND METHODS: Participants were recruited within a tertiary renal and transplant centre and invited to complete anonymized questionnaires, be involved in focus groups and undertake structured interviews. RESULTS: A total of 464 participants completed the questionnaire (36% health care professionals and 64% patients). Most perceived donor risk as small or very small (62%), and 49% stated that a potential donor should be given up to 3 months to reconsider the decision to donate. Participants were almost equally divided as to whether consensus of the donor's family is necessary (46%) or not (44%) in LDKT. Seventy-one percentage of the participants suggested that patients have a greater appreciation of a LDKT if they have been on dialysis; 58% of participants thought that donor and recipient should recuperate beside each other after surgery; 45% thought that the post-operative follow-up for the donor should last up to a year; and 83% thought that donor follow-up should include medical status and quality of life. In the interviews, participants expressed several interesting views. CONCLUSIONS: Participants believed that LDKT is safe for the donor, and the pathway to surgery and post-operative follow-up should be performed in a way that ensures lack of coercion and includes family support and an extensive post-operative follow-up.

Attitudes toward live donor kidney transplantation and its commercialization.

Development of live donor kidney transplantation (LDKT) programs has intensified debate regarding acceptability of certain donor categories and potential commercialization. Concerning these issues, we surveyed the views of medical and nursing staff caring for patients with renal failure and renal transplant recipients and donors. Participants were recruited from a tertiary transplant unit and invited to complete an anonymous questionnaire. Four hundred and sixty-four participants completed the questionnaire (42% response). One hundred and sixty-eight (36.2%) were health care professionals and 296 (63.8%) patients; 85.6% of participants were willing to donate to their children, 80.2% to siblings, 80.8% to parents, 72% to a non-blood-related relative or friend, and 15.3% to a stranger. If participants had hypothetical renal failure, they were prepared to accept a kidney from a parent (79.5%), sibling (78.7%), child (56.3%), a non-blood-related relative or friend (79.3%), or stranger (54.1%). Regarding commercialization, responders' attitudes were that the donor should not accept financial reward (29.1%), be compensated for expenses only (60.6%), or should receive a direct financial reward (10.1%). For non-directed donation, 23.5%, 55.6%, and 20.7% were not in support of reward, compensation only, and financial reward, respectively. While live kidney donation was accepted by the majority of individuals surveyed, only the minority approved of commercialization.

The Giacomini vein as an autologous conduit in infrainguinal arterial reconstruction.

The standard conduit in infrainguinal arterial bypass grafting, the great saphenous vein, is often unavailable. Arm and small saphenous veins are used as alternative conduits; yet both are deficient in length to accommodate femorocrural bypasses as a single conduit. In light of its high prevalence, the Giacomini vein harvested in continuity with the small saphenous vein may offer the latter extra length, promoting their combination into a single conduit able to meet the needs of infrainguinal reconstruction, particularly in lengthy infrainguinal bypass grafting. The Giacomini vein merits consideration when arterial reconstruction is performed in proximity to its anatomic course.