Effects of Arteriovenous Fistula Ligation on Cardiac Structure and Function in Kidney Transplant Recipients

Vascular remodeling in arteriovenous fistula treated with PDE5A inhibitors

The arteriovenous fistula (AVF) is the lifeline for hemodialysis patients. However, there are currently no effective therapies promoting AVF maturation. AVF dilation by smooth muscle cell relaxation, through increased cyclic guanosine monophosphate (cGMP), is one potential mechanism to improve AVF remodeling. In this study, we examined the cGMP pathway and its inhibitor phosphodiesterase 5A (PDE5A) in rat, pig, and human AVF. We administered the PDE5A inhibitor, sildenafil, to rats with femoral AVFs and analyzed AVF histological and hemodynamic parameters. We observed that AVF creation increases PDE5A expression in rodent and porcine AVF models. Similarly, we observed an increase in PDE5A expression in the anastomotic regions of AVFs from hemodialysis patients when compared to pre-AVF placement. Sildenafil-treated rats showed significantly increased ultrasound-derived AVF volumetric blood flow and increased MRI-derived 3-dimensional lumen diameter when compared to controls. MRI-based computational fluid dynamics showed that sildenafil-treated rats had increased anastomotic hemodynamics compared to control rats. Histology showed similar intimal hyperplasia in sildenafil-treated and control rats. In conclusion, sildenafil treatment increases AVF vein outward expansion and blood flow without affecting the level of intimal hyperplasia. PDE5A inhibitors serve as a potential therapeutic approach to promote AVF maturation by enhancing outward vascular remodeling.

Risk and management of cardiac disease in kidney and liver transplant recipients

Organ transplantation is the treatment of choice for individuals with kidney failure requiring kidney replacement therapy, as well as for those with end-stage liver disease. Despite the significant reduction in long-term morbidity and mortality with transplantation, kidney and liver allograft recipients remain at high risk for cardiovascular disease (CVD) and premature death from cardiovascular causes. This heightened risk is represented across all phenotypes of CVD, including coronary heart disease, heart failure, arrhythmias, valvulopathies and pulmonary hypertension. Pre-existing vascular risk factors for CVD, coupled with superimposed cardiovascular-kidney-metabolic derangements after transplantation, driven at least in part by post-transplant weight gain, immunosuppressive therapies and de novo risk factors such as dyslipidaemia and diabetes, coalesce to increase total CVD risk. In this review, we summarise pathophysiological considerations for both the short- and long-term increase in CVD risk following kidney/liver transplantation. We review the different phenotypes of CVD, with unique considerations for post-transplant care in this patient population. Finally, we highlight the need for awareness about long-term CVD risk and a multidisciplinary approach to managing organ-specific CVD risk in kidney and liver transplant patients.

Beyond the vascular access: unveiling the cardiovascular impact of dialysis access flow rates

OBJECTIVE

To investigate the impact of arteriovenous fistula (AVF) and arteriovenous graft (AVG) flow rates on cardiac function and blood pressure in hemodialysis patients, comparing changes before and after vascular access creation and assessing differences between high and non-high flow access groups.

METHODS

This prospective, observational study included 80 hemodialysis patients (43 males), all of Iranian ethnicity, at a university-affiliated referral hospital in Tehran, Iran. Flow rates (Qa) of vascular accesses were measured using Color Doppler ultrasonography (Acuson Sequoia system). Echocardiographic parameters, including systolic blood pressure, ejection fraction (EF), and left ventricular end-diastolic dimension (LVEDD), were assessed at baseline and six months post-intervention. Data were analyzed using paired t-tests and Pearson correlation coefficients.

RESULTS

Following vascular access creation, a significant decrease in systolic blood pressure was observed (156.48 ± 18.04 mmHg to 141.42 ± 15.82 mmHg, p < 0.001), along with a notable decline in EF (57.18% ± 6.51 to 50.31% ± 4.99, p < 0.001), and an increase in LVEDD (4.43 ± 0.27 cm to 5.51 ± 0.26 cm, p < 0.001), suggesting potential cardiovascular burden in high-flow access patients. Patients with high-flow access exhibited greater cardiovascular burden, likely due to increased cardiac output demands and risk of high-output heart failure. No significant differences in cardiac outcomes were observed between proximal and distal AVFs or upper and lower limb AVGs.

CONCLUSIONS

These findings underscore the need for proactive cardiovascular monitoring, particularly in patients with high-flow vascular access, to prevent potential complications such as high-output cardiac failure. Routine Doppler ultrasonography and echocardiographic assessments should be integrated into clinical practice to identify high-risk patients and guide timely interventions.

Associations Between Type of Hemodialysis Access and Pulmonary Hypertension: A Single-Center Retrospective Cohort

BACKGROUND

Pulmonary hypertension affects patients with hemodialysis-dependent end-stage kidney failure; however, the estimated prevalence varies greatly due to the underutilization of right heart catheterization and the evolving diagnostic criteria of pulmonary hypertension. Pulmonary hypertension in end-stage kidney failure is often attributed to arteriovenous (AV) access; therefore, we hypothesized that patients with AV fistula/graft would have a greater prevalence of pulmonary hypertension on right heart catheterization compared to those with central venous (CV) catheter accesses.

METHODS

In this retrospective single-center cohort study, we identified and randomly sampled patients from July 2012 to August 2022 receiving hemodialysis for ≥ 3 months and who underwent right heart catheterization, using Current Procedural Terminology codes. Pulmonary hypertension was defined as mean pulmonary arterial pressure (mPAP) > 20 mmHg. Our primary outcome was the prevalence of pulmonary hypertension among patients with AV fistula/graft versus CV hemodialysis access, tested with descriptive statistics. We evaluated survival as a secondary outcome using a Cox proportional hazards model.

RESULTS

A total of 3834 patient charts were extracted. Overall, 444 charts were randomly sampled, resulting in 137 subjects meeting the inclusion criteria. The mean age was 63.8 ± 10.5 years, and 62% were male. The most common etiology of end-stage kidney failure was diabetic kidney disease (57.7%). Eighty percent of end-stage kidney failure patients had pulmonary hypertension; however, the type of hemodialysis access was not associated with pulmonary hypertension (85% CV catheter vs. 79.5% AV access, p = 0.59). Patients with pulmonary hypertension had lower hemoglobin (9.6 ± 0.8 vs. 11.2 ± 1.3 g/dL, p < 0.0001) and serum albumin (2.3 ± 0.9 vs. 3.4 ± 0.6 g/dL, p < 0.0001) than those without pulmonary hypertension. Those with pulmonary hypertension had an increased risk of mortality (hazard ratio: 2.2, 95% confidence interval: 1.04-4.61; p = 0.04).

CONCLUSION

Our findings show a high burden of pulmonary hypertension among this heterogeneous cohort of end-stage kidney failure patients, with no association between pulmonary hypertension and the type of hemodialysis access. This study highlights the need for prospective investigations incorporating current strategies for pulmonary hypertension diagnosis and treatment among the dialysis-dependent population.

From Risk Assessment to Management: Cardiovascular Complications in Pre- and Post-Kidney Transplant Recipients: A Narrative Review

Kidney transplantation remains the best treatment for chronic kidney failure, offering better outcomes and quality of life compared with dialysis. Cardiovascular disease (CVD) is a major cause of morbidity and mortality in kidney transplant recipients and is associated with decreased patient survival and worse graft outcomes. Post-transplant CVD results from a complex interaction between traditional cardiovascular risk factors, such as hypertension and diabetes, and risk factors specific to kidney transplant recipients including chronic kidney disease, immunosuppressive drugs, or vascular access. An accurate assessment of cardiovascular risk is now needed to optimize the management of cardiovascular comorbidities through the detection of risk factors and the screening of hidden pretransplant coronary artery disease. Promising new strategies are emerging, such as GLP-1 receptor agonists and SGLT2 inhibitors, with a high potential to mitigate cardiovascular complications, although further research is needed to determine their role in kidney transplant recipients. Despite this progress, a significant gap remains in understanding the optimal management of post-transplant CVD, especially coronary artery disease, stroke, and peripheral artery disease. Addressing these challenges is essential to improve the short- and long-term outcomes in kidney transplant recipients. This narrative review aims to provide a comprehensive overview of cardiovascular risk assessment and post-transplant CVD management.

Left Ventricular Reverse Remodeling after Successful Living Donor Kidney Transplantation: The Visualizing the Pathophysiology of Kidney Transplantation in Modern Age Study

Key Points

Kidney transplantation (KT) can improve even advanced left ventricular (LV) geometric patterns, but this effect may be attenuated by pre-KT decreased diastolic function and acute antibody-mediated rejection. Regardless of the pre-KT LV geometric pattern, the postoperative LV geometric pattern tended to shift toward concentric remodeling. Geometric patterns may be an easy-to-understand and useful cardiac function assessment tool for nephrologists.

Background

The effect of kidney transplantation (KT) on left ventricular (LV) remodeling remains poorly understood. The aim of this study was to evaluate the effect of KT on LV reverse remodeling, using echocardiographic LV geometric patterns as a key assessment tool.

Methods

In 100 recipients who underwent living KT between 2012 and 2022, we evaluated changes in the distribution of LV geometric patterns (normal geometry, concentric remodeling [CR], eccentric hypertrophy [EH], and concentric hypertrophy [CH]) between baseline and 1 year after transplantation. These patterns were categorized on the basis of LV mass index and relative wall thickness assessed by echocardiography.

Results

Overall, LV geometric patterns improved or remained stable in 81% of recipients, with worsening in 19%. The proportion of normal geometry increased from 15% to 19% and CR from 30% to 45%, whereas EH decreased markedly from 20% to 3%. CH remained relatively stable at 33% (P = 0.036). Subgroup analysis revealed that 47% of those with pre-KT normal geometry progressed to LV remodeling, whereas 77% with CR remained stable. By contrast, 55% with EH experienced reverse remodeling and 49% with CH also showed reverse remodeling. These subgroup results suggest an interaction between the effect of KT on LV reverse remodeling and pre-KT LV geometric patterns. Multivariable analysis identified E/e′ > 9.5 (odds ratio, 2.01; 95% confidence interval, 1.10 to 3.67; P = 0.024) and acute antibody-mediated rejection (odds ratio, 2.44; 95% confidence interval, 1.01 to 5.87; P = 0.047) as independent predictors of LV remodeling progression.

Conclusions

KT can lead to improvements in even advanced LV geometric patterns, although this effect may be diminished in the presence of pre-KT diastolic dysfunction or the occurrence of acute rejection. Because recipients rarely achieve complete renal recovery, echocardiographic monitoring remains crucial after KT. Future studies are needed to establish whether these observed improvements in LV reverse remodeling directly translate into long-term reductions in cardiovascular events.

Complications on the feeding artery after an arterio-venous fistula closure in patients after kidney transplantation - a national cohort study

Background

Arteriovenous fistulas (AVFs) in kidney transplant recipients are sometimes closed, either as a policy or due to complications. We collected data on the incidence of complications after AVF closure in a national cohort of transplanted patients.

Methods

Patients who received a kidney transplant between 2000 and 2015 and had a functional AVF that was later ligated or extirpated were included. Medical records were searched for arterial complications on the arm with the closed AVF. Furthermore, all patients who were still alive in January 2023 were invited for a follow-up arterial ultrasound exam.

Results

Sixty patients were included; mean follow-up was 9.3 ± 3.8 years. There were five (8% cumulative incidence) patients with symptomatic arterial thrombosis and three (5% incidence) with a symptomatic feeding artery aneurysm. Prospective ultrasound exams were performed in 50 patients; the mean diameter of the brachial artery was almost doubled on the arm with the closed AVF (8.1 ± 3.2 versus 4.7 ± 0.7 mm; P < .001). Additional asymptomatic complications were found in nine patients (18% incidence): seven cases (14% incidence) of arterial thrombosis, some extending up to the axillary artery, and three (6% incidence) brachial artery aneurysms. All patients in whom the thrombosis spread to the brachial artery had large brachial arteries (>10 mm) or an aneurysm.

Conclusion

We observed a high cumulative incidence of arterial thrombosis (20%) and brachial artery aneurysms (10%), sometimes developing several years after AVF closure. These complications should be taken into account when contemplating closure of a well-developed AVF and an AVF-preserving approach with flow reduction surgery might be preferred in some cases.

Home Dialysis in Patients with Cardiovascular Diseases

Kidney failure with replacement therapy and cardiovascular disease are frequently comorbid. In patients with kidney failure with replacement therapy, cardiovascular disease is a major contributor to morbidity and mortality. Conventional thrice-weekly in-center dialysis confers risk factors for cardiovascular disease, including acute hemodynamic fluctuations and rapid shifts in volume and solute concentration. Home hemodialysis and peritoneal dialysis (PD) may offer benefits in attenuation of cardiovascular disease risk factors primarily through improved volume and BP control, reduction (or slowing progression) of left ventricular mass, decreased myocardial stunning, and improved bone and mineral metabolism. Importantly, although trial data are available for several of these risk factors for home hemodialysis, evidence for PD is limited. Among patients with prevalent cardiovascular disease, home hemodialysis and PD may also have potential benefits. PD may offer particular advantages in heart failure given it removes volume directly from the splanchnic circulation, thus offering an efficient method of relieving intravascular congestion. PD also avoids the risk of blood stream infections in patients with cardiac devices or venous wires. We recognize that both home hemodialysis and PD are also associated with potential risks, and these are described in more detail. We conclude with a discussion of barriers to home dialysis and the critical importance of interdisciplinary care models as one component of advancing health equity with respect to home dialysis.

Management of dialysis access in the post-transplantation patient

Arteriovenous fistula (AVF) is the preferred access for hemodialysis in patients with end-stage renal disease, and arteriovenous grafts are used when AVF creation is not feasible. Post renal transplantation, hemodialysis may be needed due to delayed graft function or transplantation failure. This review aimed to summarize current evidence on the impact of maintaining versus ligating AV access on renal function and cardiovascular outcomes post transplantation. A comprehensive review of literature was conducted, analyzing studies on the effects of AVF and AV graft maintenance or ligation on renal and cardiovascular outcomes in patients post transplantation. Evidence indicates that maintaining AVF post transplantation is associated with higher estimated glomerular filtration rate and better renal function retention, but poses risks for cardiovascular complications, such as left ventricular hypertrophy. Ligation of AVF is linked to improved cardiovascular outcomes, including reduced N-terminal pro-B-type natriuretic peptide levels, but may lead to a greater decline in estimated glomerular filtration rate. No significant difference in long-term renal allograft survival was observed between maintaining and ligating AV access. The decision to maintain or ligate AV access in patients post renal transplantation should be individualized, considering both renal function preservation and cardiovascular health. Although maintaining AVF may benefit renal function, it poses cardiovascular risks, whereas ligation can mitigate these risks without significantly affecting allograft survival.

Impact of arteriovenous fistula formation on trajectory of kidney function decline: a target trial emulation

Background

Prior nonrandomized studies have suggested nephroprotective effects of arteriovenous fistula (AVF) formation, but these are plausibly susceptible to immortal time and selection biases.

Methods

We studied patients attending nephrology clinics in the West of Scotland during 2010-22 with an estimated glomerular filtration rate (eGFR) ≤15 mL/min/1.73 m2 and no prior AVF. Using target trial emulation and a sequential trial design, we simulated a hypothetical trial that would randomize patients to either undergo AVF formation immediately or not to undergo AVF formation. The primary outcome was the difference in eGFR slope for the first 6 months of follow-up, estimated using a mixed-effects model. The secondary outcomes were 5-year absolute risks of dialysis and death, estimated using the Aalen-Johansen and Kaplan-Meier estimators respectively.

Results

A total of 1364 unique patients (mean age 51.1 years, 55.7% male) contributed 3125 person-trials, with 561 in the AVF and 2564 in the no AVF group. Mean eGFR was 12.6 mL/min/1.73 m2 and the median number of eGFR measurements per person-trial was 7 (interquartile range 4-12). Slope of eGFR decline did not differ significantly between the AVF and no AVF groups (between-group difference -0.67 mL/min/1.73 m2/year, 95% CI -1.43, 0.10). The 5-year absolute risk of dialysis was 87% (95% CI 84, 91) in the AVF group and 75% (95% CI 73, 77) in the no AVF group, and the 5-year survival probability was 77% (95% CI 70, 83) in the AVF group and 67% (95% CI 64, 69) in the no AVF group.

Conclusions

In this study of patients with advanced chronic kidney disease, there was no evidence of a nephroprotective effect of AVF formation.

Brain natriuretic peptide and N-terminal pro b-type natriuretic peptide in kidney transplantation: More than just cardiac markers

Although kidney transplantation (KT) is the best treatment option for most patients with end-stage kidney disease (ESKD) due to reduced mortality, morbidity and increased quality of life, long- term complications such as chronic kidney allograft dysfunction (CKAD) and increased cardiovascular disease burden are still major challenges. Thus, routine screening of KT recipients (KTRs) is very important to identify and quantify risks and guide preventative measures. However, no screening parameter has perfect sensitivity and specificity, and there is unmet need for new markers. In this review, we evaluate brain natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-proBNP) as promising markers for risk stratification in the kidney transplant recipients (KTRs). The usefulness of these markers are already proven in heart failure, hypertension, coronary artery disease. In the context of KT, evidence is emerging. BNP and NT-proBNP has shown to be associated with kidney function, graft failure, echocardiographic parameters, major cardiovascular events and mortality but the underlying mechanisms are not known. Although BNP and NT-proBNP interact with immune system, renin angiotensin system and sympathetic system; it is not known whether these interactions are responsible for the clinical findings observed in KTRs. Future studies are needed whether these biomarkers show clinical efficacy, especially with regard to hard outcomes such as major adverse cardiovascular events and graft dysfunction and whether routine implementation of these markers are cost effective in KTRs.

Practical Guidance for Hemodynamic Assessment by Right Heart Catheterization in Management of Heart Failure

Heart failure is a clinical syndrome characterized by the inability of the heart to meet the circulatory demands of the body without requiring an increase in intracardiac pressures at rest or with exertion. Hemodynamic parameters can be measured via right heart catheterization, which has an integral role in the full spectrum of heart failure: from ambulatory patients to those in cardiogenic shock, as well as patients being considered for left ventricular device therapy and heart transplantation. Hemodynamic data are critical for prompt recognition of clinical deterioration, assessment of prognosis, and guidance of treatment decisions. This review is a field guide for hemodynamic assessment, troubleshooting, and interpretation for clinicians treating patients with heart failure.

Long-term changes in cardiac remodelling in prevalent kidney graft recipients

BACKGROUND

Approximately 15% of kidney transplant (KT) recipients develop de novo heart failure after KT. There are scarce data reporting the long-term changes in cardiac structure and function among KT recipients. Despite the improvement in renal function, transplant-related complications as well as immunosuppressive therapy could have an impact on cardiac remodelling during follow-up. We aimed to describe the long-term changes in echocardiographic parameters in prevalent KT recipients and identify the clinical and laboratory factors associated with these changes.

METHODS

A centralised blinded review of two echocardiographic examinations after KT (on average after 17 and 39 months post-KT respectively) was performed among 80 patients (age 50.4 ± 16.2, diabetes 13.8% pre-KT), followed by linear regression to identify clinico-biological factors related to echocardiographic changes.

RESULTS

Left atrial volume index (LAVI) increased significantly (34.2 ± 10.8 mL/m2vs. 37.6 ± 15.0 mL/m2, annualised delta 3.1 ± 11.4 mL/m2/year; p = 0.034) while left ventricular ejection fraction (LVEF) decreased (62.1 ± 9.0% vs. 59.7 ± 9.9%, annualised delta -2.7 ± 13.6%/year; p = 0.04). Male sex (β = 8.112 ± 2.747; p < 0.01), pre-KT hypertension (β = 9.725 ± 4.156; p < 0.05), graft from expanded criteria donor (β = 3.791 ± 3.587; p < 0.05), and induction by anti-thymocyte globulin (β = 7.920 ± 2.974; p = 0.01) were associated with an increase in LAVI during follow-up. Higher haemoglobin (>12.9 g/dL) at the time of the first echocardiography (β = 6.029 ± 2.967; p < 0.05) and ACEi/ARB therapy (β = 8.306 ± 3.161; p < 0.05) were associated with an increase in LVEF during follow-up.

CONCLUSION

This study confirms the existence of long-term cardiac remodelling after KT despite dialysis cessation, characterised by an increase in LAVI and a decrease in LVEF. A better management of anaemia and using ACEi/ARB therapy may prevent such remodelling.

Improved Ultrasound-Guided Balloon-Assisted Maturation Angioplasty Using Drug-Eluting Balloons in the First Autogenous Arteriovenous Fistula Procedure: Early Experience

In patients with end-stage renal failure requiring hemodialysis, autogenous arteriovenous fistula (AVF) is preferred over tunneled dialysis catheters due to lower complications and costs. However, AVF maturation failure remains a common issue due to small vein size, multiple venipunctures, and other factors. Guidelines recommend using vessels of >2 mm for forearm AVFs and >3 mm for upper arm AVFs. This study investigates the use of intraoperative Doppler ultrasound (DUS)-guided Balloon-Assisted Maturation (BAM) with drug-eluting balloons (DEB) during initial AVF creation. Data from 114 AVF procedures, of which 27.2% underwent BAM, were analyzed. BAM was performed in 25 distal radio-cephalic and 6 proximal brachio-cephalic AVFs. With DUS guidance, vein stenosis was identified and treated using DEB. Technical success was achieved in all cases, with no early mortality. Early BAM-related complications were minimal, and no AVF thrombosis occurred. AVF maturation time was 15 days (SD: 3), and no further complications were reported during a mean follow-up of 10.38 months. Using BAM with DEB during AVF creation led to successful maturation and dialysis use without the need for secondary procedures. This study emphasizes the importance of identifying AVF failure risk early and utilizing DUS-guided procedures to enhance AVF outcomes. A more liberal use of intraoperative BAM could limit reinterventions in patients undergoing AVFs.

Arteriovenous fistula for haemodialysis as a predictor of de novo heart failure in kidney transplant recipients

Background

The haemodynamic effects of a functioning haemodialysis arteriovenous fistula (AVF) can cause or exacerbate heart failure (HF). We investigated whether the presence of an AVF at the time of kidney transplant (KT) is associated with de novo HF.

Methods

This was an observational cohort study including adult patients who received a KT in the West of Scotland between 2010 and 2020. We evaluated the risk and associations of pretransplant factors with de novo HF, alone and as a composite cardiovascular (CV) outcome (including non-fatal myocardial infarction, non-fatal stroke, de novo HF and CV death). Multivariable proportional hazards regression and sensitivity analyses were used to identify independent correlates of the outcomes.

Results

Among 1330 included patients, the incident rate of de novo HF after transplantation was 58/1000 person-years [95% confidence interval (CI) 50-67] in AVF patients (n = 716) compared with 33/1000 person-years (95% CI 27-41) in non-AVF patients (n = 614). De novo HF was associated with the presence of an AVF [adjusted hazard ratio (aHR) 2.14 (95% CI 1.40-3.26)], duration of dialysis [aHR 1.03/year increase (95% CI 1.01-1.04)], age at transplant [aHR 1.03/year increase (95% CI 1.02-1.05)], female sex [aHR 1.93 (95% CI 1.40-2.65)] and pretransplant diabetes [aHR 2.43 (95% CI 1.48-4.01)]. The presence of an AVF was also associated with the composite CV outcome [aHR 1.91 (95% CI 1.31-2.78)].

Conclusions

The presence of an AVF may be an underrecognized modifiable predictor of de novo HF posttransplantation.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolaemia: An expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is used for decades, lowering serum LDL-C levels by more than 70% directly after the treatment. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment goals and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Arteriovenous Fistula Closure Using a Simple Ligation Technique After Kidney Transplantation

BACKGROUNDS

There are advantages and disadvantages with closure of an arteriovenous fistula (AVF) after kidney transplantation, but some cases require closure. The general procedure for closure is angioplasty with exposure of the anastomotic site, but this is often time-consuming and complicated. We have developed a simpler, less invasive, and shorter procedure for AVF closure, in which the anastomotic site itself is not peeled off and the outflow vein close to this site is ligated using 1-0 silk. In this study, we examined the utility of this procedure.

METHODS

A retrospective case series study was conducted by review of electronic medical records of patients and surgeries. All patients (n = 52) who underwent AVF closure after kidney transplantation at our hospital between January 2008 and April 2021 were reviewed. Perioperative and long-term postoperative results were examined. This study was carried out following the ethical standards of the Declaration of Helsinki and Istanbul. Donors were not from prisoners, or from those individuals who are coerced of paid.

RESULTS

Simple ligation was performed for 46 patients (88.5%). The median time after renal transplantation was 40 (24.5-66.5) months. Median operative time and blood loss were 20 (12.2-30) minutes and 10 (5-15) mL, respectively. Two patients (4.3%) developed the aneurysm after the AVF closure using the simple ligation.

CONCLUSION

The simple ligation technique had a relatively shorter operative time and only 2 cases had aneurysm formation. These results suggest that this technique is an option for closure of an AVF after kidney transplantation.

Determinants of pulmonary hypertension in patients with end-stage kidney disease and arteriovenous access

BACKGROUND

Pulmonary Hypertension (PH) is a sequela of arteriovenous (AV) fistulas (AVF) or AV grafts (AVG) in patients with end-stage kidney disease (ESKD) due to the creation of shunt physiology and increased pulmonary blood flow. PH has been consistently associated with increased mortality but there is a paucity of data regarding management.

RESEARCH QUESTION

The objective of this study was to identify risk factors and outcomes in patients who develop PH after AVF or AVG creation for hemodialysis access.

METHODS

Using the United States Renal Data System, we identified all patients over age 18 initiated on dialysis from 2012-2019 who did not receive renal transplant. We identified a) the predictors of PH in patients with ESKD on hemodialysis; b) the independent mortality risk associated with development of PH.

RESULTS

We identified 478,896 patients initiated on dialysis from 2012-2019 of whom 27,787 (5.8 %) had a diagnosis of PH. The median age was 65 (IQR: 55-74) years and 59.1 % were male. Reduced ejection fraction, any congestive heart failure, obstructive sleep apnea, and female sex were the strongest predictors of PH diagnosis. Both AVG and AVF were also associated with an increased rate of PH diagnosis compared to catheter-based dialysis (p < 0.001). PH portended a poor prognosis and was associated with significantly increased mortality (p < 0.001).

CONCLUSIONS

Patients with AVF or AVG should be screened using echocardiography prior to creation and monitored with serial echocardiography for the development of PH, and if present, considered for revision of the AVA. This is also the first study to identify that AVG are a risk factor for PH in dialysis patients.

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.

Impact of arteriovenous fistula on flow states in the evaluation of aortic stenosis among ESKD patients on dialysis

INTRODUCTION

An arteriovenous fistula (AVF) in patients with end-stage kidney disease (ESKD) can influence flow states. We sought to evaluate if assessment of aortic stenosis (AS) by transthoracic echocardiographic (TTE) differs in the presence of AVF compared to other dialysis accesses in patients on dialysis.

METHODS

We identified consecutive ESKD patients on dialysis and concomitant AS from a single center between January 2000 and March 2021. We analyzed TTE parameters of AS severity (velocities, gradients, aortic valve area [AVA]) and hemodynamics (cardiac output [CO], valvuloarterial impedance [Zva]) and compared AS parameters in patients with AVF versus other dialysis access.

RESULTS

The cohort included 94 patients with co-prevalent ESKD and AS; mean age 66 years, 71% male; 43% Black, 24% severe AS. Dialysis access: 53% AVF, 47% others. In the overall cohort, no significant differences were noted between AVF versus non-AVF in AVA/CO/Zva, but with notable subgroup differences. In mild AS, CO was significantly higher in AVF versus non-AVF (6.3 vs. 5.2 L/min; p = .04). In severe AS, Zva was higher in the AVF versus non-AVF (4.6 vs. 3.6 mm Hg/mL/m2 ). With increasing AS severity in the AVF group, CO decreased, coupled with increase in Zva, likely counterbalancing the net hemodynamic impact of the AVF.

CONCLUSION

Among ESKD patients with AS, TTE parameters of flow states and AS severity differed in those with AVF versus other dialysis accesses and varied with progression in severity of AS. Future longitudinal assessment of hemodynamic parameters in a larger cohort of co-prevalent ESRD and AS would be valuable.

Management of an aneurysmal arteriovenous fistula in kidney transplant recipients

Aneurysms remain the most common complication of an arteriovenous fistula created for dialysis access. The management of an aneurysmal arteriovenous fistula (AAVF) in kidney transplant recipients remains contentious with a lack of clear clinical guidelines. Recipients of a functioning graft do not require the fistula for dialysis access, however risk of graft failure and needing the access at a future date must be considered. In this review we outline the current evidence in the assessment and management of a transplant recipient with an AAVF. We will describe our recommended five-step approach to assessing an AAVF in transplant patients; 1.) Define AAVF 2.) Risk assess AAVF 3.) Assess transplant graft function and future graft failure risk 4.) Consider future renal replacement therapy options 5.) Vascular mapping to assess future vascular access options. Then we will describe the current therapeutic options and when they would most appropriately be employed.

Paradoxical Worsening of Pulmonary Hypertension Following Closure of Arteriovenous Fistula: A Case Report and Literature Review

This case report presents the atypical instance of a 59-year-old female patient with end-stage renal disease (ESRD) who was initially referred to the pulmonary clinic for evaluation due to a low diffusing capacity of the lung for carbon monoxide (DLCO). Pulmonary hypertension (PH) was suspected, and a subsequent right heart catheterization (RHC) confirmed PH attributed to group 5 PH, leading to the decision to close the unused arteriovenous fistula (AVF) to manage PH. Unexpectedly, a follow-up RHC showed a worsening of PH with elevated pulmonary capillary wedge pressure (PCWP), revealing an additional component of post-capillary group 2 PH. This case emphasizes the significance of recognizing a low DLCO as a potential trigger for PH assessment, especially in patients with comorbidities like ESRD. Furthermore, it highlights the unusual yet critical occurrence of PH exacerbation following AVF closure.

Inflow Artery Aneurysmal Degeneration After Long Term Native Arteriovenous Fistula for Haemodialysis

OBJECTIVE

Inflow arterial aneurysms are a rare but serious complication after long term arteriovenous fistulae (AVF), probably due to arterial wall remodelling after an increase in flow and shear stress, and kidney transplantation with immunosuppressive therapy. This study aimed to describe the outcomes of surgical treatment and long term follow up in a large cohort.

METHODS

This prospective cohort study collected data from patients with a true inflow artery aneurysm after AVF creation that was surgically repaired between 2010 and 2022. Anastomotic and infected aneurysms or post-puncture pseudoaneurysms were excluded. Demographic data, access characteristics, symptoms, treatment strategies, and long term follow up were recorded; patency was estimated using Kaplan-Meier survival analysis.

RESULTS

During the study period, 28 patients (64% men, mean age 60.1 years) were treated surgically for aneurysmal degeneration of the axillary or brachial (n = 23) or radial (n = 5) artery after an AVF (10 distal, 18 proximal) performed a mean of 18.3 ± SD 7.9 years previously. Most AVFs were ligated or thrombosed, while all patients except one had previously received kidney transplants. Most of the cases (n = 18) were symptomatic: 13 with pain or swelling, four with distal embolisation, and one rupture. They were repaired by aneurysm partial excision and graft interposition (11 great saphenous vein, six ipsilateral basilic vein, three cephalic vein, and two PTFE graft), ligation (n = 3), or direct end to end anastomosis (n = 3). No major complications occurred before discharge, after a mean hospital stay of 2.4 days. After a mean follow up of 4.8 ± 3.3 years, three cases presented complications: two recurrent proximal brachial aneurysms were repaired with an additional proximal interposition graft (one with further late infected pseudoaneurysm) and an asymptomatic post-traumatic graft thrombosis. Five year primary and secondary patency was 84% and 96%, respectively.

CONCLUSION

Aneurysmal degeneration of the inflow artery is an unusual complication during long term follow up of AVFs. Aneurysm excision and, in general, autogenous graft interposition using the saphenous or ipsilateral arm vein is a safe and effective strategy.

Dialysis after kidney transplant failure: how to deal with this daunting task?

The best treatment for patients with end-stage kidney disease is kidney transplantation, which, if successful provides both a reduction in mortality and a better quality of life compared to dialysis. Although there has been significant improvement in short-term outcomes after kidney transplantation, long-term graft survival still remains insufficient. As a result, there has been an increase in the number of individuals who need dialysis again after kidney transplant failure, and increasingly contribute to kidney transplant waiting lists. Starting dialysis after graft failure is a difficult task not only for the patients, but also for the nephrologists and the care team. Furthermore, recommendations for management of dialysis after kidney graft loss are lacking. Aim of this narrative review is to provide a perspective on the role of dialysis in the management of patients with failed kidney allograft. Although numerous studies have reported higher mortality in patients undergoing dialysis following kidney allograft failure, reports are contrasting. A patient-centered, individualized approach should drive the choices of initiating dialysis, dialysis modality, maintenance of immunosuppressive drugs and vascular access.

Cardiac implications of upper-arm arteriovenous fistulas: A case series

BACKGROUND

Cardiovascular disease is a major cause of morbidity and mortality in patients with end-stage kidney disease. Arterio-venous fistulas (AVF), the gold standard for hemodialysis vascular access, are known to alter cardiac morphology and circulatory hemodynamics. We present a prospective case series of patients after creation of an AVF, explore the timeline for changes in their cardiac morphology, and detail considerations for clinicians.

METHODS

Patients were recruited in 2010 at multiple centers immediately prior to the creation of an upper-arm AVF and the initiation of hemodialysis. Cardiovascular magnetic resonance images were taken at intake before the creation of the AVF, 6-month follow-up, and 12-month follow-up. Image segmentation was used to measure left ventricular volume and mass, left atrial volume, and ejection fraction.

RESULTS

Eight patients met eligibility criteria. All eight patients had a net increase in left ventricular mass over enrollment, with a mean increase of 9.16 g (+2.96 to +42.66 g). Five participants had a net decrease in ejection fraction, with a mean change in ejection fraction of -5.4% (-21% to +5%). Upon visual inspection the patients with the largest ejection fraction decrease had noticeably hypertrophic and dilated ventricles. Left atrial volume change was varied, decreasing in five participants, while increasing in three participants. Changes in morphology were present at 6-month follow-up, even in patients who did not maintain AVF patency for the entirety of the 6-month period.

CONCLUSION

All patients included in this prospective case series had increases in left ventricular mass, with variability in the effects on the ejection fraction and left atrial volume. As left ventricular mass is an independent predictor of morbidity and mortality, further research to determine appropriate vascular access management in both end-stage kidney disease and kidney transplant populations is warranted.

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.

Effect of proximal artery restriction on flow reduction and cardiac function in hemodialysis patients with high-flow arteriovenous fistulas

OBJECTIVE

Arteriovenous fistula is the preferred vascular access for hemodialysis patients. High-flow arteriovenous fistula may cause high-output heart failure. Various procedures are used to reduce high-flow arteriovenous fistula. This study aimed to assess the efficacy of proximal artery restriction combined with distal artery ligation on flow reduction for high-flow arteriovenous fistula and on cardiac function and echocardiographic changes in patients undergoing hemodialysis.

METHODS

A retrospective analysis was performed on data collected from the medical records of patients undergoing hemodialysis with heart failure and high-flow arteriovenous fistula between May 2018 and May 2021. Thirty-one patients were treated with proximal artery restriction (banding juxta-anastomosis of the proximal artery) combined with distal artery ligation (anastomosis distal artery ligation). Changes in the Acute Dialysis Quality Initiative Workgroup cardiac function class, blood pressure, and echocardiography before and 6 months after flow restriction were compared, and post-intervention primary patency was followed-up.

RESULTS

The technical success rate of the surgery was 100%, and no surgery-related adverse events occurred. Blood flow and blood flow/cardiac output decreased significantly after flow restriction. Blood flow decreased from 2047.21 ± 398.08 mL/min to 1001.36 ± 240.42 mL/min, and blood flow/cardiac output decreased from 40.18% ± 6.76% to 22.34% ± 7.21% (P < .001). Post-intervention primary patency of arteriovenous fistula at 6, 12, and 24 months was 96.8%, 93.5%, and 75.2%, respectively. The Acute Dialysis Quality Initiative Workgroup cardiac function class improved significantly after 6 months of flow restriction (P < .001). The systolic and diastolic left heart function improved, as evidenced by a significant decrease in left atrial volume index, left ventricular end-diastolic/end-systolic diameters, left ventricular end-diastolic volume, left ventricular mass index, cardiac output, and cardiac index and an increase in lateral peak velocity of longitudinal contraction, average septal-lateral s', and lateral early diastolic peak velocity after flow restriction (P < .05). Systolic pulmonary artery pressure decreased from 32.36 ± 8.56 mmHg to 27.57 ± 8.98 mmHg (P < .05), indicating an improvement in right heart function.

CONCLUSIONS

Proximal artery restriction combined with distal artery ligation effectively reduced the blood flow of high-flow arteriovenous fistula and improved cardiac function.

Cure of Refractory Hypotension in a Hemodialysis Patient

We present a case of a 67-year-old male with end-stage renal disease (ESRD) on hemodialysis who was admitted to the hospital after recurrent falls secondary to postural hypotension. He was not able to tolerate fluid removal on dialysis due to persistent hypotension despite maximal doses of midodrine and developed severe edema. A right heart catheterization revealed raised biventricular filling pressure consistent with right heart failure with low systemic vascular resistance and pulmonary hypertension. Duplex ultrasound of the left arm cephalic arteriovenous fistula (AVF) revealed a blood flow of 5.6 L/min. We hypothesized the cause of his high output heart failure from an AV fistula despite the lack of an increase in blood pressure after compression of the AVF. The AVF was ligated and a tunneled hemodialysis catheter was placed. Immediately after ligation, the patient was able to tolerate fluid removal with dialysis without hypotension, leading to a significant improvement in his edema and shortness of breath. This case highlights the potential adverse cardiovascular effects of AVF and the salutary effects on ligation in appropriate clinical settings.

Association of Four Types of Vascular Access Including Arterial Superficialization with Mortality in Maintenance Hemodialysis Patients: A Nationwide Cohort Study in Japan

INTRODUCTION

Vascular access usage varies widely across countries. Previous studies have evaluated the association of clinical outcomes with the three types of vascular access, namely, arteriovenous fistula (AVF), arteriovenous graft (AVG), and tunneled and cuffed central venous catheter (TC-CVC). However, little is known regarding the association between arterial superficialization (AS) and the mortality of patients.

METHODS

A nationwide cohort study was conducted using data from the Japanese Society for Dialysis Therapy Renal Data Registry (2006-2007). We included patients aged ≥20 years undergoing hemodialysis with a dialysis vintage ≥6 months. The exposures of interest were the four types of vascular access: AVF, AVG, AS, and TC-CVC. Cox proportional hazard models were used to evaluate the associations of vascular access types with 1-year all-cause and cause-specific mortality.

RESULTS

A total of 183,490 maintenance hemodialysis patients were included: 90.7% with AVF, 6.9% with AVG, 2.0% with AS, and 0.4% with TC-CVC. During the 1-year follow-up period, 13,798 patients died. Compared to patients with AVF, those with AVG, AS, and TC-CVC had a significantly higher risk of all-cause mortality after adjustment for confounding factors: adjusted hazard ratios (95% confidence intervals) - 1.30 (1.20-1.41), 1.56 (1.39-1.76), and 2.15 (1.77-2.61), respectively. Similar results were obtained for infection-related and cardiovascular mortality.

CONCLUSION

This nationwide cohort study conducted in Japan suggested that AVF usage may have the lowest risk of all-cause mortality. The study also suggested that the usage of AS may be associated with better survival rates compared to those of TC-CVC in patients who are not suitable for AVF or AVG.

Cardiac changes following arteriovenous fistula creation in a mouse model

BACKGROUND

Arteriovenous fistula (AVF) creation may negatively affect cardiac structure and function and impact cardiovascular mortality. The objective of this study was to develop and characterize the cardiac changes following AVF creation in a murine AVF model.

METHODS

AVFs were constructed using the carotid artery and jugular vein in C57BL/6 mice. Sham-operated AVF mice served as the control group. 2D-echocardiography was performed prior to AVF creation (baseline) and at 7 and 21 days after creation in AVF and sham-operated mice. Picrosirius red was used to stain the left ventricle for collagen production.

RESULTS

The cardiac output (CO), left ventricular end diastolic (LVEDD) and systolic (LVESD) diameter, and end-diastolic (LVEDV) and systolic (LVESV) volume was significantly increased at 7 and 21 days in AVF compared to sham-operated mice. There was also a significant increase in CO, LVEDD, LVESD, LVEDV, and LVESV from baseline to 21 days within the AVF group, but not the sham-operated mice. There was a significant decrease in ejection fraction and fractional shortening at 21 days in AVF compared to sham-operated mice. Picrosirius red was significantly more prominent around both the perivascular and interstitial areas of the cardiac tissue from AVF mice compared to sham-operated AVF mice at 21 days.

CONCLUSIONS

The creation of an AVF in our murine model leads to cardiac changes such as increased cardiac output, left ventricular dilation, and cardiac fibrosis, while showing reductions of ejection fraction and fractional shortening.

Current considerations for heart-kidney transplantation

Cardiorenal syndrome is a complex syndrome characterized by dysfunction of the heart and kidneys in an interdependent fashion and is further divided into different subtypes based on primary organ dysfunction. Simultaneous Heart-Kidney transplantation is the treatment of choice for end-stage irreversible dysfunction of both organs, however it may be avoided with determination of cardiorenal subtype and management of primary organ dysfunction. This article discusses types of cardiorenal syndrome, indications and concerns regarding the use of simultaneous heart-kidney transplantation, and outlines algorithms for determination of need for dual vs. single organ transplantation.

Incidence, Clinical Correlates, and Outcomes of Pulmonary Hypertension After Kidney Transplantation: Analysis of Linked US Registry and Medicare Billing Claims

BACKGROUND

The incidence, risks, and outcomes associated with pulmonary hypertension (P-HTN) in the kidney transplant (KTx) population are not well described.

METHODS

We linked US transplant registry data with Medicare claims (2006-2016) to investigate P-HTN diagnoses among Medicare-insured KTx recipients (N = 35 512) using billing claims. Cox regression was applied to identify independent correlates and outcomes of P-HTN (adjusted hazard ratio [aHR] 95%LCLaHR95%UCL) and to examine P-HTN diagnoses as time-dependent mortality predictors.

RESULTS

Overall, 8.2% of recipients had a diagnostic code for P-HTN within 2 y preceding transplant. By 3 y posttransplant, P-HTN was diagnosed in 10.310.6%11.0 of the study cohort. After adjustment, posttransplant P-HTN was more likely in KTx recipients who were older (age ≥60 versus 18-30 y a HR, 1.912.403.01) or female (aHR, 1.151.241.34), who had pretransplant P-HTN (aHR, 4.384.795.24), coronary artery disease (aHR, 1.051.151.27), valvular heart disease (aHR, 1.221.321.43), peripheral vascular disease (aHR, 1.051.181.33), chronic pulmonary disease (aHR, 1.201.311.43), obstructive sleep apnea (aHR, 1.151.281.43), longer dialysis duration, pretransplant hemodialysis (aHR, 1.171.371.59), or who underwent transplant in the more recent era (2012-2016 versus 2006-2011: aHR, 1.291.391.51). Posttransplant P-HTN was associated with >2.5-fold increased risk of mortality (aHR, 2.572.843.14) and all-cause graft failure (aHR, 2.422.642.88) within 3 y posttransplant. Outcome associations of newly diagnosed posttransplant P-HTN were similar.

CONCLUSIONS

Posttransplant P-HTN is diagnosed in 1 in 10 KTx recipients and is associated with an increased risk of death and graft failure. Future research is needed to refine diagnostic, classification, and management strategies to improve outcomes in KTx recipients who develop P-HTN.

Clinical and Haemodynamic Effects of Arteriovenous Shunts in Patients with Heart Failure with Preserved Ejection Fraction

The arteriovenous shunt (AVS) is the most commonly used vascular access in patients receiving regular haemodialysis. The AVS may have a significant haemodynamic impact on patients with heart failure. Many studies have sought to understand the effect of AVS creation or closure on heart structure and functions, most of which use non-invasive methods, such as echocardiography or cardiac MRI. Data are mainly focused on heart failure with reduced ejection fraction and there are limited data on heart failure with preserved ejection fraction. The presence of an AVS has a significant haemodynamic impact on the cardiovascular system and it is a common cause of high-output cardiac failure. Given that most studies to date use non-invasive methods, invasive assessment of the haemodynamic effects of the AVS using a right heart catheter may provide additional valuable information.

Lung Congestion Severity in Kidney Transplant Recipients Is Not Affected by Arteriovenous Fistula Function

Lung ultrasound is a bedside technique for the assessment of pulmonary congestion. The study aims to assess the severity of lung congestion in kidney transplant recipients (KTR) in relation to arteriovenous fistula (AVF) patency. One hundred fifty-seven patients at least 12 months after kidney transplantation were recruited to participate in a cross-sectional study. Apart from routine visits, lung ultrasound at 28 typical points was performed. The patients were assigned to either AVF+ or AVF− groups. The mean number of lung ultrasound B-lines (USBLs) was 5.14 ± 4.96 with no differences between groups: 5.5 ± 5.0 in AVF+ and 4.8 ± 4.9 in AVF−, p = 0.35. The number and proportion of patients with no congestion (0–5 USBLs), mild congestion (6–15 USBLs), and moderate congestion (16–30 USBLs) were as follows: 101 (64.7%), 49 (31.4%), and 6 (3.8%), respectively. In multivariate analysis, only symptoms (OR 5.90; CI 2.43,14.3; p = 0.0001), body mass index (BMI) (OR 1.09; CI 1.03,1.17; p = 0.0046), and serum cholesterol level (OR 0.994; CI 0.998,1.000; p = 0.0452) contributed significantly to the severity of lung congestion. Lung ultrasound is a valuable tool for the evaluation of KTR. Functioning AVF in KTR is not the major factor affecting the severity of pulmonary congestion.

Increased Excess Pressure After Creation of an Arteriovenous Fistula in End-Stage Renal Disease

BACKGROUND

Reservoir-wave analysis (RWA) separates the arterial waveform into reservoir and excess pressure (XSP) components, where XSP is analogous to flow and related to left ventricular workload. RWA provides more detailed information about the arterial tree than traditional blood pressure (BP) parameters. In end-stage renal disease (ESRD), we have previously shown that XSP is associated with increased mortality and is higher in patients with arteriovenous fistula (AVF). In this study, we examined whether XSP increases after creation of an AVF in ESRD.

METHODS

Before and after a mean of 3.9 ± 1.2 months following creation of AVF, carotid pressure waves were recorded using arterial tonometry. XSP and its integral (XSPI) were derived using RWA through pressure wave analysis alone. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (CF-PWV).

RESURLTS

In 38 patients (63% male, age 59 ± 15 years), after AVF creation, brachial diastolic BP decreased (79 ± 10 vs. 72 ± 12 mm Hg, P = 0.002), but the reduction in systolic BP, was not statistically significant (133 ± 20 vs. 127 ± 26 mm Hg, P = 0.137). However, carotid XSP (14 [12-19] to 17 [12-22] mm Hg, P = 0.031) and XSPI increased significantly (275 [212-335] to 334 [241-439] kPa∙s, P = 0.015), despite a reduction in CF-PWV (13 ± 3.6 vs. 12 ± 3.5 m/s, P = 0.025).

CONCLUSIONS

Creation of an AVF resulted in increased XSP in this population, despite improvement in diastolic BP and aortic stiffness. These findings underline the complex hemodynamic impact of AVF on the cardiovascular system.

Left atrial strain: A novel "biomarker" for chronic kidney disease patients?

Cardiovascular disease and chronic kidney disease are frequently inter-connected and this association leads to an exponential growth of cardiovascular risk. This risk is currently underestimated by the existing algorithms and there is a constant need for new markers to predict adverse outcomes in this special population. In general population left atrial strain has emerged as an important tool for both the diagnosis and prognostic stratification, but data regarding its role in chronic kidney disease patients is scarce. The purpose of this review is to summarize the current evidence regarding this matter. Left atrial size and function mirror the duration and severity of increased left ventricular filling pressures. Increased left atrial volume index and impaired left atrial strain parameters are independent predictors for adverse cardiovascular events. Left atrial strain is impaired before changes in volume appear, thus being able to predict both diastolic and systolic function in chronic kidney disease patients. Finally, left atrial strain can identify renal patients with impaired exercise capacity and this could have clinical applications in the rehabilitation of this patients.

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.

Hemodialysis vascular access affects heart function and outcomes: Tips for choosing the right access for the individual patient

Chronic kidney disease is associated with increased cardiovascular morbidity and mortality. A well-functioning vascular access is associated with improved survival and among the available types of vascular access the arterio-venous (AV) fistula is the one associated with the best outcomes. However, AV access may affect heart function and, in some patients, could worsen the clinical status. This review article focuses on the specific cardiovascular hemodynamics of dialysis patients and how it is affected by the AV access; the effects of an excessive increase in AV access flow, leading to high-output heart failure; congestive heart failure in CKD patients and the contraindications to AV access; pulmonary hypertension. In severe heart failure, peritoneal dialysis (PD) might be the better choice for cardiac health, but if contraindicated suggestions for vascular access selection are provided based on the individual clinical presentation. Management of the AV access after kidney transplantation is also addressed, considering the cardiovascular benefit of AV access ligation compared to the advantage of having a functioning AVF as backup in case of allograft failure. In PD patients, who need to switch to hemodialysis, vascular access should be created timely. The influence of AV access in patients undergoing cardiac surgery for valvular or ischemic heart disease is also addressed. Cardiovascular implantable electronic devices are increasingly implanted in dialysis patients, but when doing so, the type and location of vascular access should be considered.

Flow reduction of a high-flow arteriovenous fistula in a hemodialysis patient reveals changes in natriuretic and renin-angiotensin system hormones of relevance for kidney function

Arteriovenous fistulas (AVFs) are iatrogenic vascular connections established to allow high-flow intravascular access for patients with chronic kidney disease requiring hemodialysis. The left-right flow shunt results in changes in extracellular fluid volume and blood pressure-controlling hormones that could affect the residual kidney function. We present a case where a female patient with a brachiocephalic AVF had a fistula flow of >4 L/min. To reduce the flow, a banding procedure was performed. The patient was examined prior to banding and 1 and 2 weeks thereafter. Banding resulted in a marked decrease in AVF flow from >4 to 1 L/min and was associated with reductions in N-terminal pro-brain natriuretic peptide of 51% and 67% at 1- and 2-weeks post-banding, respectively. Mid-regional pro-atrial natriuretic peptide concentrations were reduced post-banding by 17% after 1 week and 25% after 2 weeks. After 1 week, renin, angiotensin II, and aldosterone levels in plasma decreased transiently by 44%, 47%, and >86%, respectively, and returned to pre-banding levels after 2 weeks. Creatinine clearance tended to decrease while blood pressure and total body water increased 2 weeks after banding. This indicates that high-flow AVF is associated with increased natriuretic peptides and hormones of the renin-angiotensin-aldosterone system, that may balance each other regarding fluid retention and hypertension and support remaining kidney function.

To Close, Observe, or Reconstruct: The Third Way of Managing Dialysis Fistula Aneurysms in Kidney Transplant Recipients

Background: The management of patent dialysis fistulas in patients after kidney transplantation (KTx) is controversial—the options that are usually considered are the fistula’s closure or observation. Many complications of dialysis fistulas occur in patients after KTx, and immunosuppression increases the risk of fistula aneurysms and hyperkinetic flow. This study aimed to evaluate the results of dialysis fistula aneurysm treatment in patients after KTx and to compare them to procedures performed in an end-stage renal disease (ESRD) dialyzed population. Methods: We enrolled 83 renal transplant recipients and 123 ESRD patients with dialysis fistula aneurysms qualified for surgical revision to this single-center, prospective study. The results of the surgical treatment of dialysis fistula aneurysms were analyzed, and the primary, assisted primary and secondary patency rate, percentage and type of complications were also assessed. Results: For the treatment of dialysis fistula aneurysms in transplant patients, we performed dialysis fistula excisions with fistula closure in 50 patients (60.2%), excision with primary fistula reconstruction (n = 10, 12.0%) or excision with PTFE bypasses (n = 23, 27.7%). Postoperative complications occurred in 11 patients (13.3%) during a follow-up (median follow-up, 36 months), mostly in distant periods (median time after correction procedure, 11.7 months). The most common complication was outflow stenosis, followed by hematoma, dialysis fistula thrombosis and the formation of a new aneurysm and postoperative bleeding, infection and lymphocele. The 12-month primary, primary assisted and secondary patency rates of fistulas corrected by aneurysm excision and primary reconstruction in the KTx group were all 100%; in the control ESRD group, the 12-month primary rate was 70%, and the primary assisted and secondary patency rates were 100%. The 12-month primary, primarily assisted and secondary patency rates after dialysis fistula aneurysm excision combined with PTFE bypass were better in the KTx group than in the control ESRD group (85% vs. 71.8%, 90% vs. 84.5% and 95% vs. 91.7%, respectively). Kaplan–Meier analysis showed a significant difference in primary patency (p = 0.018) and assisted primary (p = 0.018) rates and a strong tendency in secondary patency rates (p = 0.053) between the KTx and ESRD groups after dialysis fistula excisions combined with PTFE bypass. No statistically significant differences in patency rates between fistulas treated by primary reconstruction and reconstructed with PTFE bypass were observed in KTx patients. Conclusions: Reconstructions of dialysis fistula aneurysms give good long-term results, with a low risk of complications. The reconstruction of dialysis fistulas can be an effective treatment method. Thus, this is an attractive option in addition to fistula ligation or observation in patients after KTx. Reconstructions of dialysis fistula aneurysms enable the preservation of the dialysis fistula while reducing various complications.

The Association of Pre-Kidney Transplant Dialysis Modality with de novo Posttransplant Heart Failure

BACKGROUND

Heart failure (HF) after kidney transplantation is a significant but understudied problem. Pretransplant dialysis modality could influence incident HF risk through differing cardiac stressors. However, whether pretransplant dialysis modality is associated with the development of posttransplant HF is unknown.

METHODS

We used the US Renal Data System to assemble a cohort of 27,701 patients who underwent their first kidney transplant in the USA between the years 2005 and 2012 and who had Medicare fee-for-service coverage for >6 months preceding their transplant date. Patients with any HF diagnosis prior to transplant were excluded. Detailed baseline patient characteristics and comorbidities were abstracted. The outcome of interest was de novo posttransplant HF. Pretransplant dialysis modality was defined as the dialysis modality used at the time of transplant. We conducted time-to-event analyses using Cox regression. Death was treated as a competing risk in the study's primary analysis. Graft failure was included as a time-varying covariate.

RESULTS

Among eligible patients, 81% were treated with hemodialysis prior to transplant, and hemodialysis patients were more likely to be male, had a shorter dialysis vintage, and had more diabetes and vascular disease diagnoses. When adjusted for all available demographic and clinical data, pretransplant treatment with hemodialysis (vs. peritoneal dialysis) was associated with a 19% increased risk in de novo posttransplant HF, with sub-distribution HR 1.19 (95% CI: 1.09-1.29).

CONCLUSIONS

Our results suggest that choice of pretransplant dialysis modality may impact the development of posttransplant HF.

An indolent cause of high-output heart failure in end-stage kidney disease-Application of the Nicoladoni-Israel-Branham test: A case report

BACKGROUND

A hemodynamically significant arteriovenous fistula (AVF) in end-stage kidney disease (ESKD) causes a high flow state, resulting in pathologic cardiovascular remodeling, and deserves timely clinical recognition.

CASE

A 55-year-old woman with history of ESKD with deceased donor kidney transplant with failing graft function and baseline creatinine of 2.8 mg/dl presented to the clinic with nocturnal cough, orthopnea, dyspnea on exertion and pedal edema. Physical exam was notable for large, aneurysmal right brachial AVF. Transthoracic echocardiography (TTE) revealed left ventricular (LV) enlargement and hypertrophy and elevated cardiac output (CO) of 10 L/min, raising a clinical concern for high-output heart failure.

DECISION MAKING

A non-invasive assessment of the hemodynamic significance of the AVF was performed using a TTE. During temporary occlusion of the AVF, it was determined that about 27% of the resting CO was attributed to the AVF, suggesting hemodynamic significance. Nicoladoni-Israel-Branham sign was negative as there was no change in patient's heart rate, but this was potentially attributed to beta-blockade and chronic loading conditions. She underwent AVF banding and 2-month later her presenting symptoms resolved, and a TTE showed a decrease in resting CO of 7.6 L/min with normalization of LV size.

CONCLUSION

This case highlights several teaching points. Firstly, in patients with ESKD, a large AVF can contribute to a high CO state resulting in maladaptive cardiovascular remodeling. Secondly, TTE evaluation of the hemodynamic contribution of an AVF can be performed with the application of the Nicoladoni-Israel-Branham sign. Finally, some experts recommend pre-emptive banding or ligation of AVF after successful kidney transplantation as this has been shown to have symptomatic and cardiovascular benefits.

The impact of location and patency of the arteriovenous fistula on quality of life of kidney transplant recipients

Background

Arteriovenous fistulae (AVFs) may remain patent after kidney transplantation (KTx), contributing to maladaptive cardiac remodeling. The flow in AVFs is associated with the diameter of its vessels and thus with the AVF location. The main objective of this study is to assess the influence of AVF location and its patency on the self-reported quality of life (QOL) of kidney transplant recipients (KTRs) with past history of hemodialysis.

Methods

To gain clinical data, during a scheduled visit, 353 KTRs were asked to fill out an anonymous questionnaire. From this group, 284 respondents were found eligible for analysis. The outcome was defined as prevalence of symptoms and health status, measured with the Left Ventricular Dysfunction-36 (LVD-36) Questionnaire in symptomatic patients.

Results

The hemodialysis patients (n = 243) were divided into two groups according to AVF location, i.e., DAVF – distally located AVF – (n = 174) and PAVF – proximally located AVF – (n = 69). The proportion of patients with heart failure (HF) was higher in PAVF group (24% vs. 12%, p = 0.0482). In the multivariable regression, PAVF, serum creatinine levels, and the presence of HF or coronary artery disease (CAD) remained independent predictors of lower functional capacity. Among patients with heart disease, the presence of active AVF was independently associated with worse functional outcome (higher LVD-36 scores).

Conclusions

The influence of persistent PAVF in KTRs seems to be unfavorable, especially when coexisting with CAD or HF. Abbreviations: AVF arteriovenous fistula; BMI body mass index; CAD coronary artery disease; D-AVF distally-located arteriovenous fistula; EC exercise capacity; HD hemodialysis; HF heart failure; KTx kidney transplantation; KTR kidney transplant recipient; LVD-36 Left Ventricle Disfunction – 36; LVEF left ventricle ejection fraction; LVH left ventricle hypertrophy; NYHA New York Heart Association; P-AVF proximally located arteriovenous fistula; PD peritoneal dialysis; PRO patient-reported outcomes; QOL quality of life.

Arteriovenous Fistula-induced Cardiac Remodeling Shows Cardioprotective Features in Mice

Objective

Arteriovenous fistulae (AVF) placed for hemodialysis have high flow rates that can stimulate left ventricular (LV) hypertrophy. LV hypertrophy generally portends poor cardiac outcomes, yet clinical studies point to superior cardiac-specific outcomes for patients with AVF when compared with other dialysis modalities. We hypothesize that AVF induce physiologic cardiac hypertrophy with cardioprotective features.

Methods

We treated 9- to 11-week-old C57Bl/6 male and female mice with sham laparotomy or an aortocaval fistula via a 25G needle. Cardiac chamber size and function were assessed with serial echocardiography, and cardiac computed tomography angiography. Hearts were harvested at 5 weeks postoperatively, and the collagen content was assessed with Masson's trichrome. Bulk messenger RNA sequencing was performed from LV of sham and AVF mice at 10 days. Differentially expressed genes were analyzed using Ingenuity Pathway Analysis (Qiagen) to identify affected pathways and predict downstream biological effects.

Results

Mice with AVF had similar body weight and wet lung mass, but increased cardiac mass compared with sham-operated mice. AVF increased cardiac output while preserving LV systolic and diastolic function, as well as indices of right heart function; all four cardiac chambers were enlarged, with a slight decrement in the relative LV wall thickness. Histology showed preserved collagen density within each of the four chambers without areas of fibrosis. RNA sequencing captured 19 384 genes, of which 857 were significantly differentially expressed, including transcripts from extracellular matrix-related genes, ion channels, metabolism, and cardiac fetal genes. The top upstream regulatory molecules predicted include activation of angiogenic (Vegf, Akt1), procardiomyocyte survival (Hgf, Foxm1, Erbb2, Lin9, Areg), and inflammation-related (CSF2, Tgfb1, TNF, Ifng, Ccr2, IL6) genes, as well as the inactivation of cardiomyocyte antiproliferative factors (Cdkn1a, FoxO3, α-catenin). The predicted downstream effects include a decrease in heart damage, and increased arrhythmia, angiogenesis, and cardiogenesis. There were no significant sex-dependent differences in the AVF-stimulated cardiac adaptation.

Conclusions

AVF stimulate adaptive cardiac hypertrophy in wild-type mice without heart failure or pathologic fibrosis. Transcriptional correlates suggest AVF-induced cardiac remodeling has some cardioprotective, although also arrhythmogenic features. (JVS–Vascular Science 2021;2:110-28.)

Clinical Relevance

Arteriovenous fistulae (AVF) are commonly used as access for hemodialysis in patients with end-stage renal disease. AVF induce a high-output state that is associated with long-term structural cardiac remodeling, including left ventricle hypertrophy, but this element has uncertain clinical significance. Although left ventricle hypertrophy has traditionally been associated with an increased risk of cardiovascular disease, clinical studies have suggested that cardiac-specific outcomes of patients with end-stage renal disease were better with AVF compared with other dialysis modalities. This study uses a mouse model of AVF to study the structural, functional, and molecular correlates of AVF-induced cardiac remodeling. It finds that AVF causes an adaptive cardiac hypertrophy without functional decline or fibrosis. Transcriptional correlates suggest an electrical remodeling and the upregulation of proangiogenic, procardiogenic, and prosurvival factors, implying that AVF-induced cardiac hypertrophy is potentially cardioprotective, but also arrhythmogenic.

Pulmonary Hypertension in Chronic Kidney Disease

There is a high prevalence of pulmonary hypertension in chronic kidney disease (CKD), with rates increasing as glomerular filtration rate declines. Pulmonary hypertension is associated with a higher risk of cardiovascular events and mortality in non-dialysis-dependent CKD stages 3 to 5, dialysis-dependent CKD, as well as kidney transplant recipients. The pathophysiology of pulmonary hypertension in CKD is multifactorial and includes higher pulmonary capillary wedge pressure caused by ischemic heart disease and cardiomyopathy, higher cardiac output caused by anemia and arteriovenous access used for hemodialysis, as well as potentially higher pulmonary vascular resistance. Treatment should focus on the underlying cause.

Consensus conference on heart-kidney transplantation

Simultaneous heart-kidney transplant (sHK) has enabled the successful transplantation of patients with end-stage heart disease and concomitant kidney disease, with non-inferior outcomes to heart transplant (HT) alone. The decision for sHK is challenged by difficulties in differentiating those patients with a significant component of reversible kidney injury due to cardiorenal syndrome who may recover kidney function after HT, from those with intrinsic advanced kidney disease who would benefit most from sHK. A consensus conference on sHK took place on June 1, 2019 in Boston, Massachusetts. The conference represented a collaborative effort by experts in cardiothoracic and kidney transplantation from centers across the United States to explore the development of guidelines for the interdisciplinary criteria for kidney transplantation in the sHK candidate, to evaluate the current allocation of kidneys to follow the heart for sHK, and to recommend standardized care for the management of sHK recipients. The conference served as a forum to unify criteria between the different specialties and to forge a pathway for patients who may need dual organ transplantation. Due to the continuing shortage of available donor organs, ethical problems related to multi-organ transplantation were also debated. The findings and consensus statements are presented.