To Ligate or Not to Ligate: A Meta-analysis of Cardiac Effects and Allograft Function following Arteriovenous Fistula Closure in Renal Transplant Recipients

A Systematic Review Exploring the Impact of Arteriovenous Fistula Ligature on High-Output Heart Failure in Renal Transplant Recipients

BACKGROUND

Cardiovascular disease is the most common cause of death in renal transplant recipients (RTrs). High-output heart failure (HoHF) is a classic problem of RTrs with patent arteriovenous fistulae (AVF). Central to the entire discipline of transplant nephrology is the ligation of AVF in RTrs, with a patent AVF presenting with signs and symptoms of HoHF. AVF ligation has long been a topic of great interest in this population. To date, little attention has been paid to the effects of arteriovenous graft ligation on HoHF. This study systematically reviews the data for AVF ligation, aiming to provide its impact on HoHF in RTrs.

METHODS

The present study adopts the Preferred Reporting Items for Systematic Reviews and Meta-analysis 2020 guidelines. Published studies were identified using a search strategy in PubMed, Scopus, PubMed Central, Science Direct, and Medline. The primary inclusion criterion for this review was RTrs with a patent AVF who exhibited clinical or imaging findings of HoHF. Articles dating back to the last decade that involved the human species were included in our review, and the search was restricted to the English language. Studies involving both male and female genders and those describing the adult population (aged > 19 years) were also a part of our inclusion criteria.

RESULTS

After applying eligibility criteria, our electronic search yielded 1,461 articles. A total of 16 studies that involved 18,735 subjects were included in our review, which comprised 6 cohort studies, 4 case reports, 2 randomized control trials, 2 narrative reviews, 1 meta-analysis, and 1 case series. While the risk of bias of the narrative reviews was low, 1 of the randomized control trials had some overall concerns. The meta-analysis included in our review had moderate risk of bias, while 4 of the 6 cohort studies were of good quality. All of the case reports and series included in our review were of good quality. Of the 12 studies that reported genders, 10,949 were male and 6,416 were female. There was a notable reduction in left ventricular mass, left ventricular mass index, left ventricular end diastolic dimension, cardiac output, velocity index, and systemic vascular resistance index upon AVF ligation.

CONCLUSIONS

A complete resolution of the clinical signs and symptoms of HoHF can be anticipated after AVF ligation in RTrs. Clinicians should always be on the lookout for signs and symptoms of cardiovascular decompensation in asymptomatic RTrs.

Differences in shuntflow (Qa), cardiac function and mortality between hemodialysis patients with a lower-arm fistula, an upper-arm fistula, and an arteriovenous graft

BACKGROUND

High-flow vascular accesses may contribute to cardiovascular morbidity and mortality in hemodialysis patients. Since shuntflow (Qa) varies between vascular access types, the current study aims to investigate differences in left ventricular hypertrophy (LVH), systolic and diastolic function parameters, and all-cause mortality between patients with a lower-arm arteriovenous fistula (AVF), an upper-arm AVF, and an arteriovenous graft (AVG).

METHODS

A post hoc analysis of 100 patients was performed in a single-center, prospective observational study. Echocardiography examinations were performed prior to the dialysis session. Qa measurements were performed using ultrasound dilution. Patient groups were categorized by vascular access type. Cox proportional hazards models were used to investigate the association of shunt type with all-cause mortality with adjustment for potential confounders including, amongst others, age, sex, diabetes, the duration of hemodialysis treatment, shunt vintage, and Qa.

RESULTS

Patients with an upper-arm AVF had significantly (p < 0.001) higher Qa (median 1902, IQR 1223-2508 ml/min) compared to patients with a lower-arm AVF (median 891, IQR 696-1414 ml/min) and patients with an AVG (median 881, IQR 580-1157 ml/min). The proportion of patients with LVH and systolic and diastolic echocardiographic parameters did not differ significantly between groups. Survival analysis showed that an upper-arm AVF was associated with a significantly lower all-cause mortality (p = 0.04) compared to a lower-arm AVF.

CONCLUSIONS

Patients with an upper-arm fistula had a higher Qa but similar systolic and diastolic cardiac function. Patients with an upper-arm fistula had a significantly lower risk of all-cause mortality compared with patients with a lower-arm fistula.

The Effect of Elective Ligation of the Arteriovenous Fistula on Cardiac and Renal Functions in Kidney Transplant Recipients

Key Points

Surgical AVF ligation in KTRs is associated with a significant increase in diastolic BP while systolic BP remains stable. AVF closure in KTRs leads to an improvement of LV and LA morphology and a decrease in serum NT-proBNP levels. There is no significant effect of AVF ligation on kidney allograft function: The eGFR remains stable over time.

Background

Kidney transplantation is considered as the best kidney replacement therapy, and arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. The systematic ligation of a functioning AVF in stable kidney transplant recipients (KTRs) remains debatable.

Methods

In this prospective study, we investigated the hemodynamic effect of the surgical closure of AVF in KTRs. Forty-three KTRs underwent an ambulatory BP monitoring before surgical closure of AVF (T0) and 12 months later (M12), as well as measurement of serum cardiac biomarkers (i.e. , soluble suppression of tumorigenicity 2, N-terminal pro b-type natriuretic peptide [NT-proBNP], and galectin-3). Serum tests were also performed 6 months after AVF closure (M6). An echocardiographic examination was performed at each time point. All serum creatinine values were collected to compare the individual eGFR slopes before versus after AVF closure. The latest measure of the AVF flow before kidney transplantation was recorded.

Results

Diastolic BP significantly rose from T0 to M12: +4.4±7.3 mm Hg (P = 0.0003) for 24h, +3.8±7.4 mm Hg (P = 0.0018) during the day, and +6.3±9.9 mm Hg (P = 0.0002) during the night, leading to an increased proportion of KTRs with European Society of Hypertension (ESH)-defined arterial hypertension after AVF ligation. No change was observed for systolic BP. NT-proBNP significantly dropped between T0 and M6 (345 [190; 553] to 230 [118; 458] pg/ml, P = 0.0001) and then remained stable from M6 to M12 while suppression of tumorigenicity 2 and galectin-3 levels did not change from T0 to M12. We observed a significant decrease in left ventricular (LV) end-diastolic volume, LV end-systolic volume, LV mass, interventricular septum diameter, left atrial volume, and tricuspid annular plane systolic excursion from T0 to M6 and then a stability from M6 to M12. LV ejection fraction and eGFR slope remained stable during the whole study. These observations remained unchanged after adjustment for AVF flow.

Conclusion

The closure of a patent AVF in KTRs is associated with elevation of diastolic BP, drop in serum NT-proBNP levels, reduction of left ventricular and atrial dimensions, and stability of eGFR slope.

Non-Traditional Non-Immunological Risk Factors for Kidney Allograft Loss-Opinion

Rates of late allograft loss have improved slowly in the last decades. Well described traditional risk factors that influence allograft survival include cardiovascular events, rejection, infections and post-transplant neoplasia. Here, we critically evaluate the influence of several non-immunological, non-traditional risk factors and describe their impact on allograft survival and cardiovascular health of kidney transplant recipients. We assessed the following risk factors: arterial stiffness, persistent arteriovenous access, mineral bone disease, immunosuppressive drugs residual levels variability, hypomagnesemia, glomerular pathological alterations not included in Banff criteria, persistent inflammation and metabolic acidosis.

High-flow arteriovenous fistula and hemodynamic consequences at 1 year after kidney transplantation

INTRODUCTION

There are only scarce data regarding the cardiovascular impact of arteriovenous fistula after kidney transplantation depending on fistula flow.

METHODS

We performed a single-center, prospective, cohort study including 49 patients with a functional fistula at 1 year from kidney transplantation. Patients were convened for a clinical work-up, a biological analysis, a fistula's Doppler ultrasonography and an echocardiography. Main judgment criterion was comparison of echocardiography parameters between patients with relative (fistula flow >1 L/min and a fistula flow/cardiac output ratio >20%), absolute high-flow fistula (fistula flow >2 L/min) and normal-flow fistula.

RESULTS

High-flow fistula frequency was 69%. Significantly higher left ventricular end-diastolic and systolic diameters were observed in this group compared with the normal-flow fistula group (53 ± 6 vs. 48 ± 7 mm; p = 0.04 and 33 ± 6 vs. 28 ± 8 mm; p = 0.02) and between the absolute and relative high-flow fistula subgroups (56 ± 6 vs. 51 ± 6 mm; p = 0.009 and 35 ± 6 vs. 31 ± 5 mm; p = 0.01). The study showed no other significant differences.

CONCLUSIONS

This study showed a significantly higher but not pathological left ventricular end-diastolic and systolic diameters values in patients with high-flow fistula compared with patients with normal-flow fistula and between patients with respectively absolute and relative high-flow fistula.

Long-Term Impact of Arteriovenous Fistula Ligation on Cardiac Structure and Function in Kidney Transplant Recipients: A 5-Year Follow-Up Observational Cohort Study

Background

The long-term effects of arteriovenous fistula (AVF) ligation on cardiovascular structure following kidney transplantation remain uncertain. A prospective randomized, controlled trial (RCT) examined the effect of AVF ligation at 6 months on cardiovascular magnetic resonance imaging (CMR)-derived parameters in 27 kidney transplant recipients compared with 27 controls. A mean decrease in left ventricular mass (LVM) of 22.1 g (95% CI, 15.0 to 29.1) was observed compared with an increase of 1.2 g (95% CI, -4.8 to 7.2) in the control group (P<0.001). We conducted a long-term follow-up observational cohort study in the treated cohort to determine the evolution of CMR-derived parameters compared with those documented at 6 months post-AVF ligation.

Methods

We performed CMR at long-term follow-up in the AVF ligation observational cohort from our original RCT published in 2019. Results were compared with CMR at 6 months postintervention. The coprimary end point was the change in CMR-derived LVM and LVM index at long-term follow-up from imaging at 6 months postindex procedure.

Results

At a median of 5.1 years (interquartile range, 4.7-5.5 years), 17 patients in the AVF ligation group were studied with repeat CMR with a median duration to follow-up imaging of 5.1 years (IQR, 4.7-5.5 years). Statistically significant further reductions in LVM (-17.6±23.0 g, P=0.006) and LVM index (-10.0±13.0 g/m², P=0.006) were documented.

Conclusions

The benefit of AVF ligation on LVM and LVM index regression appears to persist long term. This has the potential to lead to a significant reduction in cardiovascular mortality.

Vascular Access Perspectives in Patients After Kidney Transplantation

Introduction: More attention has been paid to the influence of arteriovenous fistula (AVF) on the cardiovascular system. In renal transplant recipients, some beneficial effect of an elective vascular access (VA) ligation was observed in patients with a high AVF flow. However, this strategy is not widely accepted and is in contradiction to the rule of vasculature preservation for possible future access. The aim of our study is to elucidate the vascular access function and VA perspective in the kidney transplantation (KTx) population.

Materials and Methods: KTx patients with a stable graft function were recruited to participate in this single center observational study (NCT04478968). The measurement of VA flow and vessel mapping for future vascular access was performed by a color Doppler ultrasound. The study group included 99 (63%) males and 58 (37%) females; the median age was 57 (IQR 48–64) years. The median time from the transplantation to the baseline visit was 94 (IQR 61–149) months. Median serum creatinine concentration was 1.36 (IQR 1.13–1.67) mg/dl.

Results: Functioning VA was found in 83 out of 157 (52.9%) patients. The sites were as follows: snuffbox in six (7.2%), wrist in 41 (49.4%), distal forearm in 18 (21.7%), middle or proximal forearm in eight (9.6%), upper-arm AV graft in one (1.2%), and upper-arm AVFs in nine (10.8%) patients, respectively. Blood flow ranged from 248 to 7,830 ml/min; the median was 1,134 ml/min. From the transplantation to the study visit, 66 (44.6%) patients experienced access loss. Spontaneous thrombosis was the most common, and it occurred in 60 (90.9%) patients. The surgical closure of VA was performed only in six (4%) patients of the study group with a functioning VA at the time of transplantation. Access loss occurred within the 1st year after KTx in 33 (50%) patients. Majority (50 out of 83, 60.2%) of the patients with an active VA had options to create a snuffbox or wrist AVF on the contralateral extremity. In a group of 74 patients without a functioning VA, the creation of a snuffbox or wrist AVF on the non-dominant and dominant extremity was possible in seven (9.2%) and 40 (52.6%) patients, respectively. In 10 (13.1%) patients, the possibilities were limited only to the upper-arm or proximal forearm VA on both sides. Access ligation was considered by 15 out of 83 (18.1%) patients with a patent VA.

Conclusions: In the majority of the patients, vascular access blood flow was below the threshold of the negative cardiovascular effect of vascular access. Creation of a distal AVF is a protective measure to avoid a high flow and preserve the vessels for future access. The approach to VA should be individualized and adjusted to the patient's profile.

The Role of Immunosuppressive Therapy in Aneurysmal Degeneration of Hemodialysis Fistulas in Renal Transplant Patients

BACKGROUND

Venous aneurysms are long-term complications of arteriovenous fistula (AVF) for hemodialysis with an estimated incidence rate of around 5-6%. The purpose of our study is to investigate the role of immunosuppressive therapy in the development of AVF aneurysms in renal transplant patients, and to determine whether AVF closure following transplantation is necessary.

METHODS

Forty-six patients with symptomatic venous AVF aneurysms underwent ligation and resection of their fistulas between January 2013 and January 2020. Immunohistochemical expression of CD3, CD4, and CD8 was assessed on the surgical specimens to characterize lymphocytic infiltrate in the aneurysm wall. Patients were subdivided into "Group A"-kidney transplant patients undergoing immunosuppressive therapy which was comprised of 39 patients and "Group B"-patients who had not undergone kidney transplant which was comprised of 7 patients. The 2 groups did not significantly differ in age, sex nor risk factors for aneurysms.

RESULTS

Group A showed a significantly higher aneurysm diameter (P < 0.0001), mean flow (P < 0.0001) and required a longer duration of surgery (P = 0.0007). A CD3+ lymphocytic infiltrate was significantly more common in Group A than in the Group B (90% vs 29%; P < 0.001). No significant differences in localization (adventitia, media or intima) and type (CD4+ vs CD8+) of lymphocytes were found between the 2 groups.

CONCLUSION

AVF venous aneurysms were significantly larger and with a more intense T-lymphocytic infiltrate in patients undergoing immunosuppressive therapy. This finding suggests that immunosuppressive therapy plays a role in aneurysm formation, supporting the need for AVF closure in patients with an estimated low risk of rejection.

Case report of a large cephalic vein aneurysm inducing heart failure in a renal transplant patient with radio-cephalic fistula for haemodialysis

INTRODUCTION

The autologous arteriovenous fistula (AVF) is considered the best vascular access for haemodialysis in patients with chronic kidney disease but in time can lead to several complications.

PRESENTATION OF A CASE

Herein we describe a case of a large cephalic vein aneurysm causing heart failure in a renal transplant patient being treated with radio-cephalic AVF for haemodialysis. The patient was judged to be at very high risk for potential catastrophic rupture of the aneurysm and his cardiac function was deteriorating so a surgical resection was offered. Under general anesthesia, a longitudinal incision was performed on the volar side of the forearm and the anastomotic junction was ligated. The cephalic vein aneurysm was isolated and a total resection of the vein, up to the joint of the elbow, was carried out. A specimen was also submitted for histological and immunohistochemical analysis.

DISCUSSION

At present no clear indications pertaining to the need to close an AVF after kidney transplantation exist. Some authors recommend a closing of the fistula in patients with stable renal function to prevent the onset of complications, while others advise never to close the asymptomatic fistula in order to preserve vascular access for haemodialysis in case of graft failure.

CONCLUSION

Based on our clinical experience, we suggest not ligating vascular access during the first year following transplantation with the exception of patients needing emergent closure. Otherwise, surgical closure to prevent the onset of complications could be considered a viable option in the following subset of patients: those who are 3 or more years from transplantation with good and stable renal function, those with a significant growth of venous aneurysms or have a high AVF flow rate or are young patients.