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

Pulmonary hypertension and chronic kidney disease: prevalence, pathophysiology and outcomes

Pulmonary hypertension (PH) is common in patients with chronic kidney disease (CKD) or kidney failure, with an estimated prevalence of up to 78% in those referred for right-heart catheterization. PH is independently associated with adverse outcomes in CKD, raising the possibility that early detection and appropriate management of PH might improve outcomes in at-risk patients. Among patients with PH, the prevalence of CKD stages 3 and 4 is estimated to be as high as 36%, and CKD is also independently associated with adverse outcomes. However, the complex, heterogenous pathophysiology and clinical profile of CKD-PH requires further characterization. CKD is often associated with elevated left ventricular filling pressure and volume overload, which presumably leads to pulmonary vascular stiffening and post-capillary PH. By contrast, a distinct subgroup of patients at high risk is characterized by elevated pulmonary vascular resistance and right ventricular dysfunction in the absence of pulmonary venous hypertension, which may represent a right-sided cardiorenal syndrome defined in principle by hypervolaemia, salt avidity, low cardiac output and normal left ventricular function. Current understanding of CKD-PH is limited, despite its potentially important ramifications for clinical decision making. In particular, whether PH should be considered when determining the suitability and timing of kidney replacement therapy or kidney transplantation is unclear. More research is urgently needed to address these knowledge gaps and improve the outcomes of patients with or at risk of CKD-PH.

Cardiorenal Syndromes and Their Role in Water and Sodium Homeostasis

Sodium is the main osmotically active ion in the extracellular fluid and its concentration goes hand in hand with fluid volume. Under physiological conditions, homeostasis of sodium and thus amount of fluid is regulated by neural and humoral interconnection of body tissues and organs. Both heart and kidneys are crucial in maintaining volume status. Proper kidney function is necessary to excrete regulated amount of water and solutes and adequate heart function is inevitable to sustain renal perfusion pressure, oxygen supply etc. As these organs are bidirectionally interconnected, injury of one leads to dysfunction of another. This condition is known as cardiorenal syndrome. It is divided into five subtypes regarding timeframe and pathophysiology of the onset. Hemodynamic effects include congestion, decreased cardiac output, but also production of natriuretic peptides. Renal congestion and hypoperfusion leads to kidney injury and maladaptive activation of renin-angiotensin-aldosterone system and sympathetic nervous system. In cardiorenal syndromes sodium and water excretion is impaired leading to volume overload and far-reaching negative consequences, including higher morbidity and mortality of these patients. Keywords: Cardiorenal syndrome, Renocardiac syndrome, Volume overload, Sodium retention.

Prosthetic brachial artery-external jugular vein arteriovenous grafts as a novel option for hemodialysis access: A case report

Following the exhaustion of all conventional hemodialysis access options in the upper extremities, a prosthetic arteriovenous loop was performed between the brachial artery (BA) and the external jugular vein (EJV) as a novel access option for hemodialysis in the present case report. During the procedure, a polytetrafluoroethylene graft was anastomosed to the BA and the EJV, and looped on the upper limb. The safety and reliability of BA-EJV access was evaluated by determining the complications, patency and intervention rates. The patient was then followed up for 20 months. The graft became thrombosed 20 months after the placement. There were no complications, such as infection, bleeding or aneurysmal lesions. Overall, the present study demonstrates that hemodialysis via BA-EJV access represents an unusual, yet effective and safe procedure, which may be conducted with acceptable complications and patency rates.

CZecking heart failure in patients with advanced chronic kidney disease (Czech HF-CKD): Study protocol

BACKGROUND

Heart failure (HF) is a frequent cause of morbidity and mortality of end-stage kidney disease (ESKD) patients on hemodialysis. It is not easy to distinguish HF from water overload. The traditional HF definition has low sensitivity and specificity in this population. Moreover, many patients on hemodialysis have exercise limitations unrelated to HF. Therefore, we postulated two new HF definitions ((1) Modified definition of the Acute Dialysis Quality Improvement working group; (2) Hemodynamic definition based on the calculation of the effective cardiac output). We hypothesize that the newer definitions will better identify patients with higher number of endpoints and with more advanced structural heart disease.

METHODS

Cohort, observational, longitudinal study with recording predefined endpoints. Patients (n = 300) treated by hemodialysis in six collaborating centers will be examined centrally in a tertiary cardiovascular center every 6-12 months lifelong or till kidney transplantation by detailed expert echocardiography with the calculation of cardiac output, arteriovenous dialysis fistula flow volume calculation, bio-impedance, and basic laboratory analysis including NTproBNP. Effective cardiac output will be measured as the difference between measured total cardiac output and arteriovenous fistula flow volume and systemic vascular resistance will be also assessed non-invasively. In case of water overload during examination, dry weight adjustment will be recommended, and the patient invited for another examination within 6 weeks. A composite major endpoint will consist of (1) Cardiovascular death; (2) HF worsening/new diagnosis of; (3) Non-fatal myocardial infarction or stroke. The two newer HF definitions will be compared with the traditional one in terms of time to major endpoint analysis.

DISCUSSION

This trial will differ from others by: (1) detailed repeated hemodynamic assessment including arteriovenous access flow and (2) by careful assessment of adequate hydration to avoid confusion between HF and water overload.

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.

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.

Coronary Artery Bypass Grafting in Dialysis-Dependent Patients - Key Peri-Operative Considerations

Cardiovascular disease represents the leading cause of mortality in dialysis-dependent (DD) patients, with the great majority of these patients afflicted by severe coronary artery disease. As rates of end-stage renal disease increase worldwide, DD patients represent a growing proportion of the coronary artery bypass grafting (CABG) cohort. Yet, these patients are complex, with crucial changes in their haemodynamic and physiologic profiles that complicate revascularisation surgery. First, this comprehensive literature review explores the outcomes and prognostic factors for DD patients undergoing CABG. We then summarise the intricacies relating to important peri-operative decisions such as use of cardio-pulmonary bypass and choice of conduit.

Comparison of Clinical Performance Between Two Types of Symmetric-Tip Hemodialysis Catheters: A Single-Centre, Randomized Trial

PURPOSE

To compare the clinical performance of a newly designed, symmetric-tip Arrow-Clark™ VectorFlow® tunnelled haemodialysis catheter, with a Glidepath™, symmetric-tip tunnelled haemodialysis catheter.

MATERIAL AND METHODS

From November 2018 to October 2020, patients with End-Stage Renal Disease requiring a de novo tunnelled catheter for hemodialysis, were randomized to Vectorflow® (n = 50) or to Glidepath™ catheter (n = 48). The primary outcome was catheter patency at one year following catheter insertion. Catheter failure was defined as the removal of the catheter due to infectious complications, or low blood flow rate by intraluminal thrombosis or fibrin sheath occlusion. Secondary outcomes were blood flow rate, fractional urea clearance and urea reduction ratio during dialysis.

RESULTS

Demographic characteristics were not different between the two groups. At three months and on the one-year endpoint the patency rates with the Vectorflow® catheter were 95.83% and 83.33% respectively, compared to 93.02% at both endpoints with the Glidepath™ catheter (P = 0.27). Catheter failure to infectious complications or low blood flow rate was similar in both groups. Catheter blood flow rate reached the threshold of 300 ml/min at all time points for both catheters. All patients had a high mean fractional urea clearance (1.6-1.7).

CONCLUSIONS

The catheter patency rate was not significantly different in patients with a VectorFlow® or a Glidepath™ catheter. Both catheters presented satisfactory dialysis adequacy over one year.

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.

Biomimetic cardiac tissue chip and murine arteriovenous fistula models for recapitulating clinically relevant cardiac remodeling under volume overload conditions

Cardiovascular events are the primary cause of death among dialysis patients. While arteriovenous fistulas (AVFs) are the access of choice for hemodialysis patients, AVF creation can lead to a volume overload (VO) state in the heart. We developed a three-dimensional (3D) cardiac tissue chip (CTC) with tunable pressure and stretch to model the acute hemodynamic changes associated with AVF creation to complement our murine AVF model of VO. In this study, we aimed to replicate the hemodynamics of murine AVF models in vitro and hypothesized that if 3D cardiac tissue constructs were subjected to "volume overload" conditions, they would display fibrosis and key gene expression changes seen in AVF mice. Mice underwent either an AVF or sham procedure and were sacrificed at 28 days. Cardiac tissue constructs composed of h9c2 rat cardiac myoblasts and normal adult human dermal fibroblasts in hydrogel were seeded into devices and exposed to 100 mg/10 mmHg pressure (0.4 s/0.6 s) at 1 Hz for 96 h. Controls were exposed to "normal" stretch and experimental group exposed to "volume overload". RT-PCR and histology were performed on the tissue constructs and mice left ventricles (LVs), and transcriptomics of mice LVs were also performed. Our tissue constructs and mice LV both demonstrated cardiac fibrosis as compared to control tissue constructs and sham-operated mice, respectively. Gene expression studies in our tissue constructs and mice LV demonstrated increased expression of genes associated with extracellular matrix production, oxidative stress, inflammation, and fibrosis in the VO conditions vs. control conditions. Our transcriptomics studies demonstrated activated upstream regulators related to fibrosis, inflammation, and oxidative stress such as collagen type 1 complex, TGFB1, CCR2, and VEGFA and inactivated regulators related to mitochondrial biogenesis in LV from mice AVF. In summary, our CTC model yields similar fibrosis-related histology and gene expression profiles as our murine AVF model. Thus, the CTC could potentially play a critical role in understanding cardiac pathobiology of VO states similar to what is present after AVF creation and may prove useful in evaluating therapies.

Mortality and Quality of Life with Chronic Kidney Disease: A Five-Year Cohort Study with a Sample Initially Receiving Peritoneal Dialysis

The quality of life, morbidity and mortality of people receiving renal replacement therapy is affected both by the renal disease itself and its treatment. The therapy that best improves renal function and quality of life is transplantation. Objectives: To study the quality of life, morbidity and mortality of people receiving renal replacement therapy over a five-year period. Design: A longitudinal multicentre study of a cohort of people with chronic kidney disease. Methods: Patients from the Girona health area receiving peritoneal dialysis were studied, gathering data on sociodemographic and clinical variables through an ad hoc questionnaire, quality of life using the SF-36 questionnaire, and social support with the MOS scale. Results: Mortality was 47.2%. Physical functioning was the variable that worsened most in comparison with the first measurement (p = 0.035). Those receiving peritoneal dialysis (p = 0.068) and transplant recipients (p = 0.083) had a better general health perception. The social functioning of transplant recipients improved (p = 0.008). Conclusions: People with chronic kidney disease had a high level of mortality. The dimension of physical functioning worsens over the years. Haemodialysis is the therapy that most negatively effects general health perception. Kidney transplantation has a positive effect on the dimensions of energy/vitality, social functioning and general health perception.

Comprehensive guide to managing a chronic automated red cell exchange program in sickle cell disease

Sickle cell disease (SCD) is associated with significant morbidity and mortality, and limits both the quality and quantity of life. Transfusion therapy, specifically automated red cell exchange (aRCE), plays a key role in management of SCD and is beneficial for certain indications in the chronic, outpatient setting. The approach to maintain a successful chronic aRCE program for SCD is multifaceted. This review will highlight important considerations including indications for aRCE, patient selection, transfusion medicine pearls, vascular access needs, complications of therapy, aRCE prescription, and therapy optimization. Moreover, the importance of a multidisciplinary approach with frequent communication between the services involved cannot be overstated. Ultimately, the underlying goal of a chronic RCE program is to improve the quality of life and longevity of patients with SCD.

Arteriovenous Hemodialysis Access Stenosis Diagnosed by Duplex Doppler Ultrasonography: A Review

Arteriovenous fistula (AVF) is currently the hemodialysis access with the longest life expectations for the patients. However, even the AVF is at risk for many complications, especially the development of stenosis. The latter can not only lead to inadequate hemodialysis but also lead to AVF thrombosis. Duplex Doppler ultrasonography is a very precise method, in the hands of experienced professionals, for the diagnosis of AVF complications. In this review, we summarize the ultrasound diagnostic criteria of significant stenoses and their indication for procedural therapy.

Access flow volume (Qa) and survival in a hemodialysis population: An analysis of 5208 Qa measurements over a 9-year period

BACKGROUND

Aim of the study was to determine associations between characteristics of arteriovenous access (AVA) access flow volume (Qa, mL/min) and four year freedom from cardiovascular mortality (4yr-CVM) in hemodialysis (HD) patients.

METHODS

HD patients who received a primary AVA between January 2010 and December 2017 in one center were analyzed. Initial Qa was defined as the first Qa value obtained in a well-functioning AVA by a two-needle dilution technique. Actual Qa was defined as access flow at a random point of time. Changes in actual Qa were expressed per 3-month periods. CVM was assessed according to the ERA-EDTA classification. The optimal cut-off point for initial Qa was identified by a receiver operating characteristic curve. A joint modelling statistical technique determined longitudinal associations between Qa characteristics and 4yr-CVM.

RESULTS

A total of 5208 Qa measurements (165 patients, male n = 103; age 70±12 years, autologous AVA n = 146, graft n = 19) were analyzed. During follow-up (Dec 2010-Jan 2018, median 36 months), 79 patients (48%) died. An initial Qa < 900 mL/min was associated with an increased 4y-CVM risk (HR: 4.05; 95% CI [1.94-8.43], P<0.001). After 4 years, freedom from CVM was 34% lower in patients with a Qa < 900 mL/min (53 ±7% vs. Qa ≥ 900 mL/min: 87 ±4%, P <0.001). An association between increases in actual Qa over 3-month periods and mortality was found (HR: 4.48 per 100mL/min, 95% CI [1.44-13.97], P =0.010) indicating that patients demonstrating increasing Qa were more likely to die. By contrast, actual Qa per se was not related to survival.

CONCLUSIONS

Studying novel arteriovenous access Qa characteristics may contribute to understanding excess CVM in HD patients.

Late Basilic Vein Superficialization Combined with Revision Using Distal Inflow (RUDI) Operation to Treat a Symptomatic High Flow Fistula

BACKGROUND

Vascular access (VA)-related high flows (HF) are common with brachial artery based fistulas. Flow-reduction procedures are indicated in symptomatic patients or asymptomatic ones with flows >2 L/min. However concomitant issues increase their complexity. We describe a case of a patient suffering congestive heart failure as a result of HF brachial-basilic fistula >3 L/min. A simultaneous late basilic vein transposition and revision using distal inflow (RUDI) was performed.

METHODS

A large diameter untransposed arterialized basilic vein was carefully and completely mobilized up to the proximal upper arm. After harvesting an autologous great saphenous vein (GSV) segment, a new inflow anastomosis was performed in the proximal ulnar artery. At the final stage, and after tunneling the mobilizing basilic vein in a subcutaneous semicircular configuration, an end-to-end anastomosis joining the two stumps (basilic vein outflow portion and GSV inflow arterial portion) was performed. A decision-making process in order to reach this complex option is discussed. Results Access flow and cardiac output were greatly attenuated following our approach. After a mean follow-up of 9 months no VA complications were observed, with flow still detected below 2 L/min. All cardiac symptoms and ultrasound investigations improved.

CONCLUSION

Multiple VA issues including HF pose a risk for abandonment and a challenge for the vascular surgeon. An effort toward increasing the "upper extremity life span" is advised.