The Ebb and Flow of Echocardiographic Cardiac Function Parameters in Relationship to Hemodialysis Treatment in Patients with ESRD

Different Interdialytic Intervals and Cardiorespiratory Fitness in Patients Undergoing Hemodialysis

Key Points

This is the first study exploring differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing between the 2-day and the 3-day interdialytic interval. The 3-day interdialytic interval was associated with further impaired cardiorespiratory fitness. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.

Background

Long interdialytic interval in thrice-weekly hemodialysis is associated with excess cardiovascular and all-cause mortality risk. Impaired cardiorespiratory fitness is a strong predictor of mortality in hemodialysis. This study investigated differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing (CPET) between the end of the 2-day and the 3-day interdialytic interval.

Methods

A total of 28 hemodialysis patients, randomized in two different sequences of evaluation, underwent CPET and spirometry examination at the end of the 2-day and the 3-day intervals. The primary outcome was the difference in oxygen uptake at peak exercise (VO2peak [ml/kg per minute]) assessed with CPET. Volume status was assessed with interdialytic weight gain, lung ultrasound, bioimpedance spectroscopy, and inferior vena cava measurements. A total of 14 age-matched and sex-matched controls were also evaluated. Comparisons of changes in parameters of interest were performed with paired or independent t -tests or relevant nonparametric tests, as appropriate. Bivariate correlation analyses and generalized linear mixed models were used to examine associations between changes in CPET parameters and volume indices.

Results

Hemodialysis patients at the end of both 2-day and 3-day intervals presented lower values in all major CPET parameters than controls. VO2peak (ml/kg per minute) was significantly higher at the end of the 2-day than the 3-day interval (15.2±4.2 versus 13.6±2.8; P < 0.001); the results were similar for VO2peak (ml/min) (1188±257 versus 1074±224; P < 0.001) and VO2peak (% predicted) (58.9±9.2 versus 52.3±8.6; P < 0.001). Numerical but no statistically significant differences were detected in VO2 anaerobic threshold (ml/kg per minute) and VO2 anaerobic threshold (ml/min) between the two time points. Maximal work load (90.1±23.2 versus 79.3±25.1; P < 0.001), exercise duration, heart rate at peak exercise, and oxygen pulse also showed lower values at the end of the 3-day interval. Forced expiratory volume in 1-second levels were similar between the two evaluations. Generalized linear mixed model analysis, including interdialytic weight gain as random covariate, attenuated the observed differences in VO2peak (ml/kg per minute). Changes in bioimpedance spectroscopy–derived overhydration indexes were moderately correlated with changes of VO2peak (ml/kg per minute).

Conclusions

The 3-day interval was associated with further impairment of VO2 at peak exercise. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.

Study of Respiratory Variations of Mitral Valve Diastolic Flow in Hemodialysis Patients

The respiratory variations in mitral valve (MV) Doppler flow in hemodialysis (HD) patients have not been investigated and the normal echocardiographic value is used as a reference for HD patients. The present study evaluated the respiratory variation in MV Doppler flow in HD patients to determine if it has a unique pattern. In this prospective cohort study, echocardiography was performed before and 6 h after dialysis. The transmitral spectral Doppler E wave was measured during inspiratory and expiratory phases. The percent changes in the E wave were calculated pre- and post-dialysis. The means of the percent variation in the MV inspiratory and expiratory E wave pre- and post-dialysis were 56 ± 7% and 44 ± 1.1%, respectively, with a significant reduction after dialysis (P = .000). There was a significant positive correlation between post-dialysis ∆E wave % change and post-dialysis % change in weight (r = .318; P = .000). The respiratory changes in the MV E wave in HD patients were higher than the normal reference values. This marked variation could be explained by fluid overloading in HD patients.

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.

Cardioprotective Effect of Acute Intradialytic Exercise: A Comprehensive Speckle-Tracking Echocardiography Analysis

SIGNIFICANCE STATEMENT

Hemodialysis (HD) can lead to acute left ventricular (LV) myocardial wall motion abnormalities (myocardial stunning) due to segmental hypoperfusion. Exercise during dialysis is associated with favorable effects on central hemodynamics and BP stability, factors considered in the etiology of HD-induced myocardial stunning. In a speckle-tracking echocardiography analysis, the authors explored effects of acute intradialytic exercise (IDE) on LV regional myocardial function in 60 patients undergoing HD. They found beneficial effects of IDE on LV longitudinal and circumferential function and on torsional mechanics, not accounted for by cardiac loading conditions or central hemodynamics. These findings support the implementation of IDE in people with ESKD, given that LV transient dysfunction imposed by repetitive HD may contribute to heart failure and increased risk of cardiac events in such patients.

BACKGROUND

Hemodialysis (HD) induces left ventricular (LV) transient myocardial dysfunction. A complex interplay between linear deformations and torsional mechanics underlies LV myocardial performance. Although intradialytic exercise (IDE) induces favorable effects on central hemodynamics, its effect on myocardial mechanics has never been comprehensively documented.

METHODS

To evaluate the effects of IDE on LV myocardial mechanics, assessed by speckle-tracking echocardiography, we conducted a prospective, open-label, two-center randomized crossover trial. We enrolled 60 individuals with ESKD receiving HD, who were assigned to participate in two sessions performed in a randomized order: standard HD and HD incorporating 30 minutes of aerobic exercise (HDEX). We measured global longitudinal strain (GLS) at baseline (T0), 90 minutes after HD onset (T1), and 30 minutes before ending HD (T2). At T0 and T2, we also measured circumferential strain and twist, calculated as the net difference between apical and basal rotations. Central hemodynamic data (BP, cardiac output) also were collected.

RESULTS

The decline in GLS observed during the HD procedure was attenuated in the HDEX sessions (estimated difference, -1.16%; 95% confidence interval [95% CI], -0.31 to -2.02; P = 0.008). Compared with HD, HDEX also demonstrated greater improvements from T0 to T2 in twist, an important component of LV myocardial function (estimated difference, 2.48°; 95% CI, 0.30 to 4.65; P = 0.02). Differences in changes from T0 to T2 for cardiac loading and intradialytic hemodynamics did not account for the beneficial effects of IDE on LV myocardial mechanics kinetics.

CONCLUSIONS

IDE applied acutely during HD improves regional myocardial mechanics and might warrant consideration in the therapeutic approach for patients on HD.

Estimation of pulmonary artery systolic pressure in hemodialysis patients and its association with cardiorespiratory fitness and pulmonary function

PURPOSE

To evaluate the estimated pulmonary arterial systolic pressure (PASP) through transthoracic echocardiography in hemodialysis (HD) patients and associate it with cardiorespiratory fitness and pulmonary function.

METHODS

This study was a cross-sectional analysis of HD patients that performed evaluations of cardiac function, cardiorespiratory fitness, and pulmonary function, through transthoracic echocardiography, cardiopulmonary exercise test, spirometry, and manovacuometry, respectively. All patients underwent the evaluations on a non-dialysis day.

RESULTS

Thirty-five HD patients were evaluated and separated according to the presence of probable pulmonary hypertension (PH) (estimated PASP ≥ 35 mmHg) or not (estimated PASP < 35 mmHg). Those HD patients with probable PH had the worst cardiorespiratory fitness, evaluated by the peak oxygen consumption (VO_2peak) (17.11 ± 4.40 versus 12.90 ± 2.73 mL/kg/min; p = 0.011), and pulmonary function, evaluated by absolute and predicted of forced vital capacity (FVC) (85.52 ± 12.29 versus 71.38 ± 11.63%; p = 0.005) and absolute and predicted of forced expiratory volume in the first second (FEV₁) (83.37 ± 14.98 versus 69.21 ± 13.48%; p = 0.017). The secondary analysis showed that estimated PASP was correlated with VO_2peak (r = - 0.508; p = 0.002), FVC (r = - 0.450; p = 0.007), and FEV₁ (r = - 0.361; p = 0.033). Moreover, the adjusted odds ratio by HD vintage, dry weight and gender showed that increments in VO_2peak (OR 1.62; CI 95% 1.04-2.54; p = 0.034), FVC (OR 39.67; CI 95% 1.74-902.80; p = 0.021), and FEV₁ (OR 39.54; CI 95% 1.89-826.99; p = 0.018) were associated with 1-fold and 39-fold higher chance, respectively, for not having PH. However, all these associations were lost when age was included in the analysis.

CONCLUSIONS

The HD patients with probable PH had the worst cardiorespiratory fitness and pulmonary function. Exploratory analyses showed that greater cardiopulmonary fitness was associated with better cardiac function. Moreover, increments in cardiorespiratory fitness and pulmonary function may increase the chance of not having PH.

Why is Intradialytic Hypotension the Commonest Complication of Outpatient Dialysis Treatments?

Intradialytic hypotension (IDH) is the most frequent complication of hemodialysis (HD) treatments with a frequency of 10% to 12% for patients with chronic kidney disease attending for outpatient treatments and is associated with both temporary ischemic stress to vital organs, including the heart and brain, and increased patient mortality. Although there have been many different definitions of IDH over the years, an absolute nadir systolic blood pressure (SBP) has the strongest association with patient outcomes. The unifying pathophysiology is one of reduced effective blood volume, resulting in lower plasma tonicity, and if this cannot be adequately compensated for by activation of neurohumeral systems, then arteriolar tone and blood pressure fall. The risk factors for developing IDH are numerous, ranging from patient-related factors, including age and comorbidity with reduced cardiac reserve, to patient compliance with dietary and lifestyle advice, to reactions with the extracorporeal circuit and medications, choice of dialysate composition and temperature, setting of postdialysis target weight, ultrafiltration rate, and profiling. Advances in dialysis machine technology by providing real time estimates of the effective circulating volume and adjusting dialysate composition to maintain vascular tonicity are being developed, but currently require more sophisticated biofeedback loops to be clinically effective in preventing IDH. While awaiting advances in artificial intelligence, the clinician continues to rely on patient education to limit interdialytic weight gains, frequent assessment of the postdialysis target weight, adjusting dialysate composition and temperature, introducing convective therapies to increase thermal losses, and altering dialysis session duration and frequency to reduce ultrafiltration rate requirements.

Comparative efficacy of exercise modalities for cardiopulmonary function in hemodialysis patients: A systematic review and network meta-analysis

Background

To provide reliable evidence to exercise rehabilitation therapists and clinicians, we compared and analyzed the effects of different exercise modalities on cardiopulmonary function in hemodialysis patients using Bayesian network meta-analysis.

Methods

PubMed, OVID, Web of Science, Cochrane Library, Embase, Scopus, CINAHL, SPORT Discus, SinoMed, CNKI, Wanfang, and VIP were searched from inception to July 20, 2022. We included randomized controlled trials comparing 12 exercise modalities to improve cardiorespiratory fitness in hemodialysis patients. All statistical analysis was performed using STATA and R.

Result

A total of 82 randomized controlled trials involving 4146 maintenance hemodialysis patients were included in this study. The pair-wise meta-analysis showed that all exercise modalities had a positive effect on all indicators of cardiorespiratory capacity. The network meta-analysis demonstrated that Blood flow restriction training (BFRT), Cycle exercise (CE), Inspiratory muscle training (IMT), Combined aerobic and resistance training (CT), and Aerobic training (AT) were significantly better than usual care for 6-min walkability; Medium intensity continuous training (MICT), CT, CE, and AT were considerably better than usual care for VO₂Peak; body and mind training (MBT) and CT significantly improved SBP compared to usual care; and only MBT was significantly better than usual care for DBP. Both the two-dimensional plot and the radar plot demonstrated that CT had the best combined-effect on each index of cardiorespiratory fitness. Subgroup and sensitivity analyses demonstrated the robustness of the results. The evidence was mainly "low" to "very low" for this network meta-analysis.

Conclusion

There is no one exercise that can achieve the best effect on all of the outcomes. The benefits of MBT in decreasing arterial blood pressure are unsurpassed by other exercise methods. The intervention effect of the CT is better and more stable. Electrical muscle stimulation training (MEST) can be employed in individuals who do not wish to exercise actively but may cause an increase in blood pressure. On the basis of the characteristics of different exercise types, guidelines developers, clinicians, and patients may employ them appropriately.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails.

Echocardiographic changes after arteriovenous fistula creation in hemodialysis patients

BACKGROUND

Pulmonary hypertension (PH) is common in end-stage renal disease (ESRD) patients and is associated with increased all-cause and cardiovascular mortality in this group. There is scarce data on the long-term effect of arteriovenous fistula (AVF) creation on pulmonary hypertension (PH) and the reflected changes in echocardiographic measurements.

MATERIALS AND METHODS

This is a retrospective study of 54 patients who underwent AVF creation between 2009 and 2014 and with echocardiographic evaluations before and after surgery. We analyzed pairwise changes in right ventricular systolic pressure (RVSP), right atrial pressure (RAP) during systole, left ventricular mass (LVM), tricuspid regurgitation (TR), mitral E/E' ratio, and ejection fraction (EF), as well as the factors that predicted change in RVSP after surgery.

RESULTS

The median time for the preoperative echocardiogram was 0.3 years (interquartile range (IQR) 0.2 - 0.7 years) prior to AVF creation, while the follow-up echo was done 1.3 (0.6 - 2.1) years after surgery. 67% of the patients had RVSP &gt; 37 mmHg at baseline. There was a significant reduction in RVSP after AVF creation compared to baseline (median 33 (IQR 26 - 43) vs. 46 mmHg, p = 0.0015), with 59% of the patients experiencing a decrease and 19% remaining stable. There were also significant decreases in LVM (201 (143 - 256) vs. 215 (163 - 276), p = 0.045) and RAP systole (10 (10 - 15) vs. 3 (3 - 8); p &lt; 0.001) after surgery. Higher preoperative weight (p = 0.038) and RVSP (p = 0.006), and use of loop diuretics (p = 0.015) were significantly associated with improvement in RVSP after AVF creation.

CONCLUSION

Our results suggest that AVF creation is associated with a significant reduction or stable measurements of RVSP in the ESRD population, likely due to an improvement in volume status.

Lung Ultrasound as a Tool to Evaluate Fluid Accumulation in Dialysis Patients

BACKGROUND

Volume overload is the main mechanism of BP elevation in end-stage kidney disease (ESKD) patients undergoing hemodialysis or peritoneal dialysis and has been linked to adverse outcomes and increased mortality in this population.

SUMMARY

This review discusses current knowledge on lung ultrasound as a tool for detection of extracellular volume overload through evaluation of extravascular lung water content. We describe the principles of lung US, the main protocols to apply it in clinical practice, and accumulated data evidence regarding its associations with cardiovascular events and mortality. We also summarize available evidence on the effect of lung ultrasound-guided -volume management strategies on BP control, echocardiographic parameters, and major outcomes in patients undergoing dialysis.

KEY MESSAGES

Among interventions attempting to reduce the burden of cardiovascular disease in ESKD, effective management of volume overload represents an unmet clinical need. Assessment of hydration status by lung ultrasound is a cheap, easy to employ, and real-time technique that can offer accurate dry weight assessment leading to several clinical benefits.

Lung ultrasound guided dry-weight reduction and echocardiographic changes in clinically euvolemic hypertensive hemodialysis patients: 12-month results of a randomized controlled trial

BACKGROUND

Left ventricular hypertrophy (LVH) and dysfunction are highly prevalent in hemodialysis patients and independently associated with adverse outcomes. This study examines the long-term effects of dry-weight reduction with a standardized lung-ultrasound (US)-guided strategy on echocardiographic indexes of left ventricular (LV) mass and function in hemodialysis patients.

METHODS

Seventy-one clinically euvolemic, hemodialysis patients with hypertension were randomized to dry-weight reduction guided by pre-hemodialysis lung US (n=35) or standard-of-care treatment (n=36) and were followed-up for 12 months. Two-dimensional and tissue-Doppler echocardiography (TDI) were performed at baseline and study-end.

RESULTS

During follow-up, dry-weight reduction took place in more patients in the active than in the control arm of the trial (71.4% vs 22.2%; p<0.001). Left atrial (LA) surface (-1.37±4.50 vs 1.28±5.00 cm²; P=0.006) and LA volume index (-3.22±11.82 vs 4.76±12.83 ml/m²; P=0.009) decreased in the active and increased in the control group. LV end-diastolic volume (-0.94±11.45 vs 6.58±13.92 ml/m²; P=0.015) decreased only in the active group. LV mass index was unchanged in the active (134.21±44.75 vs 133.57±45.51; P=0.844) and marginally increased in the control group (134.21±40.96 vs 143.77±50.04 g/m²; P=0.089). LV E/e' wave ratio was unchanged in the active (12.45±4.69 vs 12.56±4.89; P=0.521) and increased in the usual-care group (10.91±4.97 vs12.36±6.43; P=0.003). LV systolic function did not differ among the two study arms across the trial.

CONCLUSIONS

Over 12 months, lung-US-guided dry-weight reduction is associated with reverse LV and LA remodeling, myocardial hypertrophy regression and improved LV diastolic filling properties.

Ultrafiltration rate and incident atrial fibrillation among older individuals initiating hemodialysis

BACKGROUND

Higher ultrafiltration (UF) rates are associated with numerous adverse cardiovascular outcomes among individuals receiving maintenance hemodialysis. We undertook this study to investigate the association of UF rate and incident atrial fibrillation in a large, nationally representative US cohort of incident, older hemodialysis patients.

METHODS

We used the US Renal Data System linked to the records of a large dialysis provider to identify individuals ≥67 years of age initiating hemodialysis between January 2006 and December 2011. We applied an extended Cox model as a function of a time-varying exposure to compute adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of delivered UF rate and incident atrial fibrillation.

RESULTS

Among the 15 414 individuals included in the study, 3177 developed atrial fibrillation. In fully adjusted models, a UF rate >13 mL/h/kg (versus ≤13 mL/h/kg) was associated with a higher hazard of incident atrial fibrillation [adjusted HR 1.19 (95% CI 1.07-1.30)]. Analyses using lower UF rate thresholds (≤10 versus >10 mL/h/kg and ≤8 versus >8 mL/h/kg, separately) yielded similar results. Analyses specifying the UF rate as a cubic spline (per 1 mL/h/kg) confirmed an approximately linear dose-response relationship between the UF rate and the risk of incident atrial fibrillation: risk began at UF rates of ~6 mL/h/kg and the magnitude of this risk flattened, but remained elevated, at rates ≥9 mL/h/kg.

CONCLUSION

In this observational study of older individuals initiating hemodialysis, higher UF rates were associated with higher incidences of atrial fibrillation.

Cardiac geometry, function, and remodeling patterns in patients under maintenance hemodialysis and peritoneal dialysis treatment

Cardiovascular disease is the leading cause of mortality in patients with end-stage-kidney disease. Evidence on the possible echocardiographic differences between hemodialysis and peritoneal dialysis (PD) is scarce. This study aimed to evaluate differences in left (LA) and right atrial (RA), left (LV) and right ventricular (RV) geometry, systolic and diastolic function in hemodialysis, and PD patients. Thirty-eight hemodialysis and 38 PD patients were matched for age, sex, and dialysis vintage. Two-dimensional and tissue-Doppler echocardiography, and lung ultrasound were performed during an interdialytic day in hemodialysis and before a programmed follow-up visit in PD patients. Vena cava diameter (11.09 ± 4.53 vs. 14.91 ± 4.30 mm; p < 0.001) was significantly lower in hemodialysis patients. Indices of LA, RA, LV, and RV dimensions were similar between the two groups. LVMi (116.91 [38.56] vs. 122.83 [52.33] g/m² ; p = 0.767) was similar, but relative wall thickness was marginally (0.40 [0.14] vs. 0.45 [0.15] cm; p = 0.055) lower in hemodialysis patients. LV hypertrophy prevalence was similar between groups (73.7% vs. 71.1%; p = 0.798), but hemodialysis patients presented eccentric and PD patients concentric LVH. Regarding ventricular systolic function, stroke volume (p = 0.030) and cardiac output (p = 0.036) were higher in hemodialysis, while RV systolic pressure (RVSP) (20.37 [22.54] vs. 27.68 [14.32] mm Hg; p = 0.009) was higher in PD. No significant differences were evidenced in diastolic function indices and lung water excess between the two groups. A moderate association was noted between ultrasound B-lines score and LA volume index (r = 0.465, p < 0.001), RVSP (r = 0.431, p < 0.001), and E/e' ratio (r = 0.304, p = 0.009). Hemodialysis and PD patients present largely similar echocardiographic indices reflecting cardiac geometry, systolic, and diastolic function, but different patterns of abnormal LV remodeling.

Right Ventricular Functionality Following Hemodialysis Initiation in End-Stage Kidney Disease-A Single-Center, Prospective, Cohort Study

Background and Objectives: Two-dimensional speckle tracking echocardiography (2D-STE) is viewed as an outstanding technique, competent of uncovering earlier subclinical myocardial anomalies compared to conventional echocardiography. A few endeavors adopted 2D-STE as a tool to estimate right ventricular (RV) function in subjects with end-stage kidney disease (ESKD). There is no published prospective study on an adult ESKD cohort exploring the consequences of commencing elective hemodialysis (HD) on RV behavior. Materials and Methods: We investigated the RV systolic function using traditional (tricuspid annular plane systolic excursion-TAPSE, RV fractional area change-FAC) and 2D-STE (RV free wall longitudinal strain-RVFWLS) parameters following the initiation of HD. We enrolled 79 consecutive patients with ESKD and assessed them in four steps-at baseline, before HD, and at 3, 6, and 12 months. Results: RVFWLS, FAC, and TAPSE values had a significant increase at 3, 6, and 12 months from baseline (p < 0.001) and a significant increase at 6 months from 3 months (p < 0.001). However, differences between 12 months and 6 months were not significant (p > 0.05) according to Dunn-Bonferroni post hoc tests. Seventeen deaths were recorded before the completion of the study. RVFWLS, FAC, and TAPSE values significantly decreased at 3 and 6 months in all 17 deceased patients, in clear opposition with the values survivors had. All the studied parameters had a significant prediction power on mortality (p < 0.001) having an outstanding performance: baseline-RVFWLS (AUC: 1.000 (95% C.I.: 1.000-1.000)), baseline-FAC (AUC: 0.974 (95% C.I.: 0.942-1.000)), and baseline-TAPSE (AUC: 0.962 (95% C.I.: 0.920-1.000). Conclusions: Our study is the first to investigate RV function by 2D-STE and correlate it with traditional methods in patients with ESKD before and after the initiation of HD. RV function was significantly ameliorated at 3, 6, and 12 months compared to the pre-HD values. FAC and RVFWLS gain an outstanding prognostic role on mortality in this population.

Assessment of Exercise Intolerance in Patients with Pre-Dialysis CKD with Cardiopulmonary Function Testing: Translation to Everyday Practice

BACKGROUND

Chronic kidney disease (CKD) is often characterized by increased prevalence of cardiovascular risk factors and increased incidence of cardiovascular events and death. Reduced cardiovascular reserve and exercise intolerance are common in patients with CKD and are associated with adverse outcomes.

SUMMARY

The gold standard for identifying exercise limitation is cardiopulmonary exercise testing (CPET). CPET provides an integrative evaluation of cardiovascular, pulmonary, hematopoietic, neuropsychological, and metabolic function during maximal or submaximal exercise. It is useful in clinical setting for differentiation of the causes of exercise intolerance, risk stratification, and assessment of response to relevant treatments. A number of recent studies have used CPET in patients with pre-dialysis CKD, aiming to assess the cardiovascular reserve of these individuals, as well as the effect of interventions such as exercise training programs on their functional capacity. This review provides an in-depth description of CPET methodology and an overview of studies that utilized CPET technology to assess cardiovascular reserve in patients with pre-dialysis CKD. Key Messages: CPET can delineate multisystem changes and offer comprehensive phenotyping of factors determining overall cardiovascular risk. Potential clinical applications of CPET in CKD patients range from objective diagnosis of exercise intolerance to preoperative and long-term risk stratification and providing intermediate endpoints for clinical trials. Future studies should delineate the association of CPET indexes, with cardiovascular and respiratory alterations and hard outcomes in CKD patients, to enhance its diagnostic and prognostic utility in this population.

Volume overload in hemodialysis: diagnosis, cardiovascular consequences, and management

Volume overload in haemodialysis (HD) patients associates with hypertension and cardiac dysfunction and is a major risk factor for all-cause and cardiovascular mortality in this population. The diagnosis of volume excess and estimation of dry weight is based largely on clinical criteria and has a notoriously poor diagnostic accuracy. The search for accurate and objective methods to evaluate dry weight and to diagnose subclinical volume overload has been intensively pursued over the last 3 decades. Most methods have not been tested in appropriate clinical trials and their usefulness in clinical practice remains uncertain, except for bioimpedance spectroscopy and lung ultrasound (US). Bioimpedance spectroscopy is possibly the most widely used method to subjectively quantify fluid distributions over body compartments and produces reliable and reproducible results. Lung US provides reliable estimates of extravascular water in the lung, a critical parameter of the central circulation that in large part reflects the left ventricular end-diastolic pressure. To maximize cardiovascular tolerance, fluid removal in volume-expanded HD patients should be gradual and distributed over a sufficiently long time window. This review summarizes current knowledge about the diagnosis, prognosis and treatment of volume overload in HD patients.

Cardiac Imaging in Dialysis Patients

There is a well-established yet unexplained high prevalence of cardiovascular morbidity and mortality in individuals with end-stage kidney disease receiving dialysis. Potential causes include changes in cardiac structure and function, with increased left ventricular mass index as the best established cardiac structural change associated with this increase in mortality. However, in recent years, new echocardiographic and cardiac magnetic resonance imaging techniques have emerged that may provide novel markers that may better explain the mechanisms underlying the cardiovascular morbidity and mortality observed in end-stage kidney disease. This review outlines advances in cardiac imaging and the current status of imaging modalities, including echocardiography, cardiac magnetic resonance imaging, and cardiac positron emission tomography, to identify dialysis patients at high risk for cardiovascular mortality.

Cardiovascular Functional Changes in Chronic Kidney Disease: Integrative Physiology, Pathophysiology and Applications of Cardiopulmonary Exercise Testing

The development of cardiovascular disease during renal impairment involves striking multi-tiered, multi-dimensional complex alterations encompassing the entire oxygen transport system. Complex interactions between target organ systems involving alterations of the heart, vascular, musculoskeletal and respiratory systems occur in Chronic Kidney Disease (CKD) and collectively contribute to impairment of cardiovascular function. These systemic changes have challenged our diagnostic and therapeutic efforts, particularly given that imaging cardiac structure at rest, rather than ascertainment under the stress of exercise, may not accurately reflect the risk of premature death in CKD. The multi-systemic nature of cardiovascular disease in CKD patients provides strong rationale for an integrated approach to the assessment of cardiovascular alterations in this population. State-of-the-art cardiopulmonary exercise testing (CPET) is a powerful, dynamic technology that enables the global assessment of cardiovascular functional alterations and reflects the integrative exercise response and complex machinery that form the oxygen transport system. CPET provides a wealth of data from a single assessment with mechanistic, physiological and prognostic utility. It is an underutilized technology in the care of patients with kidney disease with the potential to help advance the field of cardio-nephrology. This article reviews the integrative physiology and pathophysiology of cardio-renal impairment, critical new insights derived from CPET technology, and contemporary evidence for potential applications of CPET technology in patients with kidney disease.

Heart Failure and Atrial Fibrillation Modify the Associations of Nocturnal Blood Pressure Dipping Pattern With Mortality in Hemodialysis Patients

Heart failure (HF), hypertension, and abnormal nocturnal blood pressure dipping are highly prevalent in hemodialysis patients. Atrial fibrillation (AF) and HF might be important mediators for the association of abnormal dipping patterns with worse prognosis. Thus, the aim of this study is to investigate the association of dipping with mortality in hemodialysis patients and to assess the influence of AF and HF. In total, 525 hemodialysis patients underwent 24-hour ambulatory blood pressure monitoring. All-cause and cardiovascular mortality served as end points. Patients were categorized according to their systolic dipping pattern (dipper, nondipper, and reverse dipper). Cox regression analysis was performed to determine the association between dipping pattern and study end points with dipping as reference. Subgroup analysis was performed for patients with and without AF or HF. In total, 185 patients with AF or HF and 340 patients without AF or HF were included. During a median follow-up of 37.8 months, 177 patients died; 81 from cardiovascular causes. Nondipping and reverse dipping were significantly associated with all-cause mortality in the whole cohort (nondipper: hazard ratio, 1.95 [1.22-3.14]; P=0.006; reverse dipper: hazard ratio, 2.31 [1.42-3.76]; P<0.001) and in patients without AF or HF (nondipper: hazard ratio, 2.78 [1.16-6.66]; P=0.02; reverse dipper: hazard ratio, 4.48 [1.87-10.71]; P<0.001) but not in patients with AF or HF. For cardiovascular mortality, associations were again significant in patients without AF or HF and in the whole cohort. The observed associations remained significant after adjustment for possible confounders. This study provides well-powered evidence for the association between abnormal dipping patterns and mortality in hemodialysis patients and suggests that HF or AF modifies this association.

Free Standing, Large-Area Silicon Nitride Membranes for High Toxin Clearance in Blood Surrogate for Small-Format Hemodialysis

Developing highly-efficient membranes for toxin clearance in small-format hemodialysis presents a fabrication challenge. The miniaturization of fluidics and controls has been the focus of current work on hemodialysis (HD) devices. This approach has not addressed the membrane efficiency needed for toxin clearance in small-format hemodialysis devices. Dr. Willem Kolff built the first dialyzer in 1943 and many changes have been made to HD technology since then. However, conventional HD still uses large instruments with bulky dialysis cartridges made of ~2 m² of 10 micron thick, tortuous-path membrane material. Portable, wearable, and implantable HD systems may improve clinical outcomes for patients with end-stage renal disease by increasing the frequency of dialysis. The ability of ultrathin silicon-based sheet membranes to clear toxins is tested along with an analytical model predicting long-term multi-pass experiments from single-pass clearance experiments. Advanced fabrication methods are introduced that produce a new type of nanoporous silicon nitride sheet membrane that features the pore sizes needed for middle-weight toxin removal. Benchtop clearance results with sheet membranes (~3 cm²) match a theoretical model and indicate that sheet membranes can reduce (by orders of magnitude) the amount of membrane material required for hemodialysis. This provides the performance needed for small-format hemodialysis.

Indexation of left ventricular mass to predict adverse clinical outcomes in pre-dialysis patients with chronic kidney disease: KoreaN cohort study of the outcome in patients with chronic kidney disease

Background

No study has compared the clinical impact of indexation of left ventricular mass (LVM) on adverse clinical outcomes in pre-dialysis patients with chronic kidney disease (CKD).

Methods

We reviewed 2,101 patients from a large-scale multi-center prospective study that gathered anthropometric and echocardiographic measurements and clinical outcomes. The LVM was indexed as body surface area (LVMI-BSA) and height raised to the power of 2.7 (LVMI-H2.7). The main outcomes were composite renal and cardiovascular events and all-cause mortality. Left ventricular hypertrophy (LVH) was defined as the highest sex-specific quartile of LVMI-BSA or LVMI-H2.7.

Results

During a mean period of 3.5 years, 692 patients developed composite outcomes (32.9%). The area under the curve at 5 year of LVM (60.6%) for composite outcome was smaller than that for LVMI-BSA (63.2%, P <0.001) and LVMI-H2.7 (63.4%, P <0.001). The hazard ratio (HR) and 95% confidence interval (CI) per one unit increase in LVM (g), LVMI-BSA (g/m²), and LVMI-H2.7 (g/m^2.7) for composite outcomes were 1.004 (1.002–1.005, P <0.001), 1.011 (1.006–1.016, P <0.001), and 1.023 (1.012–1.035, P <0.001), respectively. Patients with LVH determined by LVMI-BSA and LVMI-H2.7 (HR 1.352, 95% CI 1.123–1.626, P = 0.001) and LVH determined by only LVMI-BSA (HR 1.908, 95% CI 1.233–2.953, P = 0.004) showed an independent increase in the risk of composite-outcome development, when compared with patients without LVH, according to LVMI-BSA and LVMI-H2.7.

Conclusion

Indexation of LVM improved the prediction of adverse outcomes. BSA may be as useful as height^2.7 in indexing of LVM for predicting adverse outcomes in pre-dialysis patients with CKD.

Acute stunning effect of hemodialysis on myocardial performance: A three-dimensional speckle tracking echocardiographic study

The effects of acute changes during hemodialysis (HD) on the myocardium are not yet known. The invention of three-dimensional speckle tracking echocardiography (3DSTE) has offered clinicians a new method to assess the movements of ventricular segments simultaneously in three spatial directions. The aim of this study was to evaluate the effect of first weekly standard HD process on the left ventricle (LV) and right ventricle (RV) global and regional myocardial function in patients with normal left ventricle ejection fraction using 3DSTE-derived indices. Patients (n=38) receiving maintenance HD in our clinic who have no known cardiovascular disease are examined just before and after a HD session using 3DSTE. Demographic and comorbidity data, renal replacement treatment characteristics, and laboratory test results are recorded. 3DSTE analysis is performed to calculate the LV global longitudinal, circumferential area and radial peak systolic strain, as well as RV septum and free-wall longitudinal strain and fractional area change. Patients are aged 52.8 ± 13.6 years and 52.6% of them are male. Mean dialysis duration is 56 months. The LV strain values of the patients changed markedly before and after HD (GLS: -14.2 ± 5.2, -11.1 ± 4.6 [P < .001], GCS: -14.8 ± 4.2, -12.4 ± 5.28 [P < .009]; GRS: 41.5 ± 16, 33.3 ± 16.5 [P = .003]; AREA -24.7 ± 7.2, -20.1 ± 7.6 [P = .001], respectively). We could not demonstrate any improvement in RV strain values before or after HD. LV strain values are positively correlated with blood pressure variability during the dialysis sessions. LV function is preserved better after HD in patients on beta or calcium channel blocker therapy compared to those who do not use these agents (P < .001, P < .01, respectively). HD treatment results in deterioration in all LV strain directions but not in RV. Strain assessment may improve vascular risk stratification of patients on chronic HD.

Diagnosis and Management of Pulmonary Hypertension in Patients With CKD

Pulmonary hypertension (PH) is a highly prevalent and important condition in adults with chronic kidney disease (CKD). In this review, we summarize the definition of PH, discuss its pathophysiology and classifications, and describe diagnostic and management strategies in patients with CKD, including those with kidney failure treated by kidney replacement therapy. In the general population, PH is classified into 5 groups based on clinical presentation, pathology, hemodynamics, and management strategies. In this classification system, PH in CKD is placed in a diverse group with unclear or multifactorial mechanisms, although underlying cardiovascular disease may account for most cases. CKD may itself directly incite pulmonary circulatory dysfunction and remodeling through uremic toxins, inflammation, endothelial dysfunction, and altered vasoregulation. Despite several studies describing the higher prevalence of PH in CKD and kidney failure, along with an association with poor outcomes, high-quality evidence is not available for its diagnostic and management strategies in those with CKD. In CKD not requiring kidney replacement therapy, volume management along with treatment of underlying risk factors for PH are critical. In those receiving hemodialysis, options are limited and transition to peritoneal dialysis may be considered if recurrent hypotension precludes optimal volume control.

The effects of intradialytic exercise on hemodialysis adequacy: A systematic review

Dialysis adequacy is an independent predictor of high mortality rates in hemodialysis patients. Intradialytic exercise is a potential strategy to increase uremic solute removal by increasing blood flow to low perfusion tissue beds. The purpose of this review is to establish the efficacy of intradialytic exercise for hemodialysis adequacy. Additionally, this review aims to provide practical information to aid health care professionals implement intradialytic exercise for dialysis adequacy. Database and hand searches identified 15 published interventional studies that implemented intradialytic exercise for dialysis adequacy as a primary outcome measure in adult maintenance hemodialysis patients. Data pertaining to dialytic solute clearance of urea, creatinine, beta₂ microglobulin, phosphate, and potassium were extracted. Mean differences, normalized to percentages, and effect sizes were calculated and reported. The current data pertaining to the use of intradialytic exercise for improving dialysis adequacy in terms of Kt/V_urea or small molecule uremic toxin clearance are equivocal. Limited data showed that intradialytic exercise has no effect middle molecule toxin (beta₂ - microglobulin) clearance. Intradialytic exercise favored increased phosphate removal showing medium to large effects for reduced serum concentrations, reduced rebound and increased clearance. In summary, supervised light to moderate intradialytic aerobic cycling appears to be beneficial for increasing phosphate removal and may be an adjunct therapy for patients failing to meet clinical phosphate targets. Further work is required to establish the effect of intradialytic exercise on Kt/V_urea and other middle molecule and protein bound solutes. Research aimed at establishing the most effective exercise prescription for improved solute clearance is warranted.

Impact of hemodialysis on cardiovascular system assessed by pulse wave analysis

Valuable information about cardiovascular system can be derived from the shape of aortic pulse wave being the result of reciprocal interaction between heart and vasculature. Pressure profiles in ascending aorta were obtained from peripheral waveforms recorded non-invasively (SphygmoCor, AtCor Medical, Australia) before, during and after hemodialysis sessions performed after 3-day and 2-day interdialytic intervals in 35 anuric, prevalent hemodialysis patients. Fluid status was assessed by Body Composition Monitor (Fresenius Medical Care, Bad Homburg, Germany) and online hematocrit monitoring device (CritLine, HemaMetrics, Utah). Systolic pressure and ejection duration decreased during dialysis. Augmentation index remained stable at 30 ± 13% throughout hemodialysis session despite the decrease of augmented pressure and pulse height. Subendocardial viability ratio (SEVR) determined after 3-day and 2-day interdialytic intervals increased during the sessions by 43.8 ± 26.6% and 26.1 ± 25.4%, respectively. Hemodialysis performed after 3-day and 2-day interdialytic periods reduced significantly overhydration by 2.4 ± 1.0 L and 1.8 ± 1.2 L and blood volume by 16.3 ± 9.7% and 13.7 ± 8.9%, respectively. Intradialytic increase of SEVR correlated with ultrafiltration rate (R = 0.39, p-value < 0.01), reduction in overhydration (R = -0.57, p-value < 0.001) and blood volume drop (R = -0.38, p-value < 0.01). The strong correlation between the decrease of overhydration during hemodialysis and increase in SEVR confirmed that careful fluid management is crucial for proper cardiac function. Hemodialysis affected cardiovascular system with the parameters derived from pulse-wave-analysis (systolic and augmented pressures, pulse height, ejection duration, SEVR) being significantly different at the end of dialysis from those before the session. Combination of pulse-wave-analysis with the monitoring of overhydration provides a new insight into the impact of hemodialysis on cardiovascular system.