Advances in the cardiovascular assessment of patients with chronic kidney disease

Echocardiographic manifestations in end-stage renal disease

End-stage renal disease (ESRD) is a common but profound clinical condition, and it is associated with extremely increased morbidity and mortality. ESRD can represent four major echocardiographic findings-myocardial hypertrophy, heart failure, valvular calcification, and pericardial effusion. Multiple factors interplay leading to these abnormalities, including pressure/volume overload, oxidative stress, and neurohormonal imbalances. Uremic cardiomyopathy is characterized by left ventricular (LV) hypertrophy and marked diastolic dysfunction. In ESRD patients on hemodialysis, LV geometry is changeable bidirectionally between concentric and eccentric hypertrophy, depending upon changes in corporal fluid volume and arterial pressure, which eventually results in a characteristic of LV systolic dysfunction. Speckle tracking echocardiography enabling to detect subclinical disease might help prevent future advancement to heart failure. Heart valve calcification also is common in ESRD, keeping in mind which progresses faster than expected. In a modern era, pericardial effusion observed in ESRD patients tends to result from volume overload, rather than pericarditis. In this review, we introduce and discuss those four echocardiography-assessed findings of ESRD, with which known and conceivable pathophysiologies for each are incorporated.

Non-invasive intradialytic percutaneous perfusion monitoring: a view to the heart through the skin

Introduction

The life-sustaining treatment of hemodialysis (HD) induces recurrent and cumulative systemic circulatory stress resulting in cardiovascular injury. These recurrent insults compound preexisting cardiovascular sequalae leading to the development of myocardial injury and resulting in extremely high morbidity/mortality. This is largely a consequence of challenged microcirculatory flow within the myocardium (evidenced by detailed imaging-based studies). Currently, monitoring during HD is performed at the macrovascular level. Non-invasive monitoring of organ perfusion would allow the detection and therapeutic amelioration of this pathophysiological response to HD. Non-invasive percutaneous perfusion monitoring of the skin (using photoplethysmography-PPG) has been shown to be predictive of HD-induced myocardial stunning (a consequence of segmental ischemia). In this study, we extended these observations to include a dynamic assessment of skin perfusion during HD compared with directly measured myocardial perfusion during dialysis and cardiac contractile function.

Methods

We evaluated the intradialytic microcirculatory response in 12 patients receiving conventional HD treatments using continuous percutaneous perfusion monitoring throughout HD. Cardiac echocardiography was performed prior to the initiation of HD, and again at peak-HD stress, to assess the development of regional wall motion abnormalities (RWMAs). Myocardial perfusion imaging was obtained at the same timepoints (pre-HD and peak-HD stress), utilizing intravenous administered contrast and a computerized tomography (CT)-based method. Intradialytic changes in pulse strength (derived from PPG) were compared with the development of HD-induced RWMAs (indicative of myocardial stunning) and changes in myocardial perfusion.

Results

We found an association between the lowest pulse strength reduction (PPG) and the development of RWMAs (p = 0.03) and also with changes in global myocardial perfusion (CT) (p = 0.05). Ultrafiltration rate (mL/kg/hour) was a significant driver of HD-induced circulatory stress [(associated with the greatest pulse strength reduction (p = 0.01), a reduction in global myocardial perfusion (p = 0.001), and the development of RWMAs (p = 0.03)].

Discussion

Percutaneous perfusion monitoring using PPG is a useful method of assessing intradialytic hemodynamic stability and HD-induced circulatory stress. The information generated at the microcirculatory level of the skin is reflective of direct measures of myocardial perfusion and the development of HD-induced myocardial stunning. This approach for the detection and management of HD-induced cardiac injury warrants additional evaluation.

Implications of uremic cardiomyopathy for the practicing clinician: an educational review

Studies over recent years have redeveloped our understanding of uremic cardiomyopathy, defined as left ventricular hypertrophy, congestive heart failure, and associated cardiac hypertrophy plus other abnormalities that result from chronic kidney disease and are often the cause of death in affected patients. Definitions of uremic cardiomyopathy have conflicted and overlapped over the decades, complicating the body of published evidence, and making comparison difficult. New and continuing research into potential risk factors, including uremic toxins, anemia, hypervolemia, oxidative stress, inflammation, and insulin resistance, indicates the increasing interest in illuminating the pathways that lead to UC and thereby identifying potential targets for intervention. Indeed, our developing understanding of the mechanisms of UC has opened new frontiers in research, promising novel approaches to diagnosis, prognosis, treatment, and management. This educational review highlights advances in the field of uremic cardiomyopathy and how they may become applicable in practice by clinicians. Pathways to optimal treatment with current modalities (with hemodialysis and angiotensin-converting enzyme inhibitors) will be described, along with proposed steps to be taken in research to allow evidence-based integration of developing investigational therapies.

Hypoxia during maintenance hemodialysis-the critical role of pH

Background

The impact and management of subclinical hypoxia during hemodialysis is a significant medical challenge. As key determinants of O₂ availability and delivery, proposed mechanisms contributing to hypoxia include ischemia, alkalemia and pulmonary leukocyte sequestration. However, no study has comprehensively investigated and compared these interrelated mechanisms throughout a typical hemodialysis treatment week. This study aimed to comprehensively assess the physiological mechanisms that contribute to hypoxia during hemodialysis.

Methods

In 76 patients, we measured arterial blood gases and pH at four time-points during hemodialysis (start, 15 min, 60 min, end) over the course of a standard treatment week. For the mid-week hemodialysis session, we additionally measured central hemodynamics (non-invasive cardiac output monitoring) and white blood cell count.

Results

Linear regression modelling identified changes in pH, but not central hemodynamics or white blood cell count, to be predictive of changes in PaO₂ throughout hemodialysis (e.g. at 60 min, β standardized coefficient pH = 0.45, model R² = 0.25, P < .001). Alkalemia, hypokalemia, decreased calcium and increased hemoglobin-O₂ affinity (leftward shift in the oxyhemoglobin dissociation curve) were evident at the end of hemodialysis. pH and hemoglobin-O₂ affinity at the start of hemodialysis increased incrementally over the course of a standard treatment week.

Conclusion

These data highlight the important role of pH in regulating O₂ availability and delivery during hemodialysis. Findings support routine pH monitoring and personalized dialysate bicarbonate prescription to mitigate the significant risk of alkalemia and subclinical hypoxia.

The Added Value of Atrial Strain Assessment in Clinical Practice

Speckle tracking echocardiography has emerged as a sensitive tool to analyze myocardial function with improved diagnostic accuracy and prognostic value. Left atrial strain assessment has become a novel imaging method in cardiology with superior prognostic value compared to conventional left atrial volume indices. Left atrial function is divided into three phases, reservoir function being the most important. This review summarizes the added value of speckle tracking echocardiography derived left atrial strain assessment in clinical practice. Recently published data suggest the prognostic value of left atrial reservoir function in heart failure, atrial fibrillation, stroke and valvular heart disease. Furthermore, left atrial reservoir strain proved to be a predictor of cardiovascular morbidity and mortality in the general population. Thus, routine assessment of left atrial function can be an optimal strategy to improve cardiovascular risk prediction and supplement the current risk prediction models.

Uraemic Cardiomyopathy: A Review of Current Literature

Uraemic Cardiomyopathy (UC) is recognised as an intricate and multifactorial disease which portends a significant burden in patients with End-Stage Renal Disease (ESRD). The cardiovascular morbidity and mortality associated with UC is significant and can be associated with the development of arrythmias, cardiac failure and sudden cardiac death (SCD). The pathophysiology of UC involves a complex interplay of traditional implicative factors such as haemodynamic overload and circulating uraemic toxins as well as our evolving understanding of the Chronic Kidney Disease-Mineral Bone Disease pathway. There is an instrumental role for multi-modality imaging in the diagnostic process; including transthoracic echocardiography and cardiac magnetic resonance imaging in identifying the hallmarks of left ventricular hypertrophy and myocardial fibrosis that characterise UC. The appropriate utilisation of the aforementioned diagnostics in the ESRD population may help guide therapeutic approaches, such as pharmacotherapy including beta-blockers and aldosterone-antagonists as well as haemodialysis and renal transplantation. Despite this, there remains limitations in effective therapeutic interventions for UC and ongoing research on a cellular level is vital in establishing further therapies.

Hemodynamic response to non-pneumatic anti-shock compression garments in patients with renal dysfunction

Background

Patients with chronic kidney disease are at higher risk of developing cardiovascular disease. Chronic exposure to intermittent hemodialysis may be a source of added stress to the cardiovascular system; intradialytic hypotension is a common complication of hemodialysis, and repeated events may lead to hemodynamic stress and ischemic injuries. Administration of non-pneumatic compression stockings to the lower limbs has demonstrated hemodynamic stabilizing effects in other settings and may provide similar benefits in the kidney disease population. Therefore, we conducted this pilot study assessing the feasibility and tolerability of the application of non-pneumatic compression stockings to patients with kidney disease. We also assessed the changes in hemodynamic measurements following the application of the compression stockings to explore the biological feasibility of this being an effective intervention for intradialytic hypotension.

Methods

Fifteen individuals were enrolled in the study (5 healthy, 5 chronic kidney disease patients, and 5 dialysis patients). Outcomes including hemodynamic parameters such as cardiac output, peripheral vascular resistance, and blood pressure were measured using continuous pulse wave analysis. Changes in global longitudinal strain were measured via echocardiography. These outcome measurements were made before and after the application of compression stockings.

Results

All study participants tolerated the compression garments well and without complication. Hemodynamic response to lower body compression caused varying effects on cardiac output, mean arterial pressure and global longitudinal strain. Some individuals saw large improvements in hemodynamic parameters while in others the opposite effect was observed. No consistent response was elicited.

Conclusions

Application of compression stockings to patients with renal dysfunction is well-tolerated. However, significant variations in hemodynamic outcomes exist, and may be a barrier for larger scale trials without prior identification of specific patient characteristics indicating likely benefit from the application of external compression.

Trial registration

ClinicalTrials.gov, Identifier: NCT02915627, Registration Date: Sept 27, 2016.

Cardiac Imaging in Heart Failure with Comorbidities

Imaging modalities stand at the frontiers for progress in congestive heart failure (CHF) screening, risk stratification and monitoring. Advancements in echocardiography (ECHO) and Magnetic Resonance Imaging (MRI) have allowed for improved tissue characterizations, cardiac motion analysis, and cardiac performance analysis under stress. Common cardiac comorbidities such as hypertension, metabolic syndromes and chronic renal failure contribute to cardiac remodeling, sharing similar pathophysiological mechanisms starting with interstitial changes, structural changes and finally clinical CHF. These imaging techniques can potentially detect changes earlier. Such information could have clinical benefits for screening, planning preventive therapies and risk stratifying patients. Imaging reports have often focused on traditional measures without factoring these novel parameters. This review is aimed at providing a synopsis on how we can use this information to assess and monitor improvements for CHF with comorbidities.

Mortality in hemodialysis patients over 65 years of age

INTRODUCTION

Based on the statistics the population in Bosnia and Herzegovina is getting older. In 2013 the average life span for women was 73.6 years and 68.1 for men. The chronic hemodialysis program is mainly reserved for elderly patients with high mortality risk. The most common cause of hemodialysis mortality relates to cardiovascular diseases (60.2%), regardless of frequent innovations and improvement of hemodialysis procedures.

THE AIM OF THE STUDY

was to determine the mortality rate by age groups with comments on the presence of non-traditional predictors (anemia, hypoalbuminemia, CRP, vascular access and PTH) in dialysis patients in the follow-up period of 36 months.

METHODS

The study included all patients undergoing chronic hemodialysis treatment at the Clinic of Hemodialysis of the Clinical Center University of Sarajevo (CCUS).

RESULTS

Out of a total number of hemodialysis patients (n=232), the specific mortality rate in patients under 65 years of age was 16.8%, and 50.5% in patients over 65 years of age. According to the age groups the mortality rate in elderly patients is as follows: from 65 to 74 years (45.1%), from 75 to 84 years (55.0%), over ≥85 years (75.0%). The most frequent vascular access in patients under and above 65 is arteriovenous fistula (79.6% and 62.1 %), temporary hemodialysis catheter (11.7% and 43.8 %) and long-term hemodialysis catheter (8.8% and 4.2 %). In the age group under 65 years of age the temporary hemodialysis catheter is significantly and more frequently used in diseased patients in respect to survivors (34.8% vs. 7.0%) [χ(2)(2)=15.769, p=0.001]. Diseased patients from the age group over 65 had a significantly lower mean value of haemoglobin in blood (M=100.9±17.5 g/L) in respect to survivors (M=109.2±17.1)[t(93)=2.339; p=0.021], lower mean value of albumin in blood (Me=32.0; IQR=29.0 do 35.0) in respect to survivors (Me=34.0; IQR=32.0 to 38.0) [U=762.5; p=0.006], and higher mean value of CRP in blood (Me=19.3 mg/L; IQR=6.6 to 52.0) in respect to survivors (Me=7.8; IQR=4.0 to 16.7) [U=773.5; p=0.008]. Diseased patients belonging to the age group over 65 had lower mean value of PTH, but without statistical significance (p>0.05).

CONCLUSION

older age, temporary vascular access, anaemia and hypoalbuminemia are strong predictors of mortality in hemodialysis patients. Old age does not present contraindication for hemodialysis treatment, and treatment of terminal renal illness should not be abandoned.

Ergocalciferol and microcirculatory function in chronic kidney disease and concomitant vitamin d deficiency: an exploratory, double blind, randomised controlled trial

BACKGROUND AND OBJECTIVES

Vitamin D deficiency and endothelial dysfunction are non-traditional risk factors for cardiovascular events in chronic kidney disease. Previous studies in chronic kidney disease have failed to demonstrate a beneficial effect of vitamin D on arterial stiffness, left ventricular mass and inflammation but none have assessed the effect of vitamin D on microcirculatory endothelial function.

STUDY DESIGN

We conducted a randomised controlled trial of 38 patients with non diabetic chronic kidney disease stage 3-4 and concomitant vitamin D deficiency (<16 ng/dl) who received oral ergocalciferol (50,000 IU weekly for one month followed by 50,000 IU monthly) or placebo over 6 months. The primary outcome was change in microcirculatory function measured by laser Doppler flowmetry after iontophoresis of acetylcholine. Secondary endpoints were tissue advanced glycation end products, sublingual functional capillary density and flow index as well as macrovascular parameters. Parallel in vitro experiments were conducted to determine the effect of ergocalciferol on cultured human endothelial cells.

RESULTS

Twenty patients received ergocalciferol and 18 patients received placebo. After 6 months, there was a significant improvement in the ergocalciferol group in both endothelium dependent microcirculatory vasodilatation after iontophoresis of acetylcholine (p = 0.03) and a reduction in tissue advanced glycation end products (p = 0.03). There were no changes in sublingual microcirculatory parameters. Pulse pressure (p = 0.01) but not aortic pulse wave velocity was reduced. There were no significant changes in bone mineral parameters, blood pressure or left ventricular mass index suggesting that ergocalciferol improved endothelial function independently of these parameters. In parallel experiments, expression of endothelial nitric oxide synthase and activity were increased in human endothelial cells in a dose dependent manner.

CONCLUSIONS

Ergocalciferol improved microcirculatory endothelial function in patients with chronic kidney disease and concomitant vitamin D deficiency. This process may be mediated through enhanced expression and activity of endothelial nitric oxide synthase.

TRIAL REGISTRATION

Clinical trials.gov NCT00882401.