Acute kidney injury and mortality following ventricular assist device implantation

Supporting the right ventricle in postcardiotomy renal dysfunction: A case series

Postcardiotomy RV dysfunction is an under-recognized cause of acute kidney injury (AKI). Insertion of a percutaneous right ventricular assist device (RVAD) reduces central venous hypertension and congestive nephropathy by augmenting cardiac output. In selected patients, percutaneous RVAD insertion may improve renal function and obviate the need for long-term dialysis.

Heart, kidney and left ventricular assist device: a complex trio

BACKGROUND

Heart failure (HF) is a complex syndrome affecting the whole body, kidneys included. The left ventricular assist device (LVAD) is a valid option for patients with very severe HF. Focusing on renal function, LVAD implantation could theoretically reverse the detrimental effects of HF syndrome on kidneys. However, implanting an LVAD is a high-risk surgical procedure, and LVAD patients have higher risk of bleeding, device thrombosis, strokes, renal impairment, multi-organ failure and infections. Furthermore, an LVAD has its own particular effects on the renal system.

METHODS

In this review, we provide a comprehensive overview of the complex interaction between LVAD and the kidneys from the pathophysiological and clinical perspectives. An analysis of the different effects of pulsatile-flow and continuous-flow LVAD is provided.

RESULTS

Despite their limitations, creatinine-based estimated glomerular filtration rate (eGFR) formulas help to stratify patients by their post-LVAD placement prognosis. Poor basal renal function, the onset of acute kidney injury or the need for renal replacement therapy after LVAD implantation negatively influences a patient's prognosis. LVAD can also prompt an improvement in renal function, however, with some counterintuitive effects on a patient's prognosis.

CONCLUSION

It is still hard to say whether different trends in eGFR depend on different renal conditions before LVAD placement, on a patient's better overall status or on a particular patient management strategy before and/or after the device's implantation. Steps should be taken to solve this question because finding the best candidates for LVAD implantation is of paramount importance to ensure the best outcomes.

Urinary Cell-Cycle Arrest Biomarkers as Early Predictors of Acute Kidney Injury After Ventricular Assist Device Implantation or Cardiac Transplantation

OBJECTIVES

Acute kidney injury (AKI) remains a leading source of morbidity and mortality after cardiothoracic surgery. Insulin-like growth factor-binding protein 7 (IGFBP7), and tissue inhibitor of metalloproteinases-2 (TIMP-2), are novel early-phase renal biomarkers that have been validated as sensitive predictors of AKI. Here the authors studied the efficacy of these biomarkers for predicting AKI after left ventricular assist device (LVAD) implantation and cardiac transplantation.

DESIGN/SETTING/PARTICIPANTS/INTERVENTIONS

This was a prospective study of 73 patients undergoing LVAD implantation (n = 37) or heart transplant (n = 36) from 2016 to 2017 at the authors' center. TIMP-2 and IGFBP7 were measured with the NephroCheck Test on urine samples before surgery and one-to-six hours after surgery. NephroCheck scores were assessed as predictors of moderate/severe AKI (Kidney Disease International Global Outcomes 2/3 creatinine criteria) within 48 hours of surgery, and the association with survival to one year was investigated.

MEASUREMENTS AND MAIN RESULTS

The LVAD and transplant cohorts overall were similar in demographics and baseline creatinine (p > 0.05), with the exception of having more African-American patients in the LVAD arm (p = 0.003). Eleven (30%) LVAD and 16 (44%) transplant patients developed moderate/severe AKI. Overall, AKI was associated with postsurgery NephroCheck (odds ratio [95% confidence interval] for 0.1 mg/dL increase: 1.36 [1.04-1.79]; p = 0.03), but not with baseline NephroCheck (p = 0.92). When analyzed by cohort, this effect remained for LVAD (1.68 [1.05-2.71]; p = 0.03) but not for transplant (p = 0.15). Receiver operating characteristic analysis showed postoperative NephroCheck to be superior to baseline creatinine in LVAD (p = 0.046). Furthermore, an increase of 0.1 mg/dL in postoperative NephroCheck was associated with a 10% increase in the risk of mortality (adjusted hazard ratio: 1.11 [1.01-1.21]; p = 0.04) independent of age and body mass index.

CONCLUSION

Assessment of TIMP-2 and IGFBP7 within six hours after surgery appeared effective at predicting AKI in patients with LVADs. Larger studies are warranted to validate these findings.

Incidence and impact of acute kidney injury on patients with implantable left ventricular assist devices: a Meta-analysis

Background: We aimed to evaluate the acute kidney injury (AKI) incidence and its associated risk of mortality in patients with implantable left ventricular assist devices (LVAD).Methods: A systematic literature search in Ovid MEDLINE, EMBASE, and Cochrane Databases was conducted through January 2020 to identify studies that provided data on the AKI incidence and AKI-associated mortality risk in adult patients with implantable LVADs. Pooled effect estimates were examined using random-effects, generic inverse variance method of DerSimonian-Laird.Results: Fifty-six cohort studies with 63,663 LVAD patients were enrolled in this meta-analysis. The pooled incidence of reported AKI was 24.9% (95%CI: 20.1%-30.4%) but rose to 36.9% (95%CI: 31.1%-43.1%) when applying the standard definition of AKI per RIFLE, AKIN, and KDIGO criteria. The pooled incidence of severe AKI requiring renal replacement therapy (RRT) was 12.6% (95%CI: 10.5%-15.0%). AKI incidence did not differ significantly between types of LVAD (p = .35) or indication for LVAD use (p = .62). While meta-regression analysis did not demonstrate a significant association between study year and overall AKI incidence (p = .55), the study year was negatively correlated with the incidence of severe AKI requiring RRT (slope = -0.068, p < .001). The pooled odds ratios (ORs) of mortality at 30 days and one year in AKI patients were 3.66 (95% CI, 2.00-6.70) and 2.22 (95% CI, 1.62-3.04), respectively. The pooled ORs of mortality at 30 days and one year in severe AKI patients requiring RRT were 7.52 (95% CI, 4.58-12.33) and 5.41 (95% CI, 3.63-8.06), respectively.Conclusion: We found that more than one-third of LVAD patients develop AKI based on standard definitions, and 13% develop severe AKI requiring RRT. There has been a potential improvement in the incidence of severe AKI requiring RRT for LVAD patients. AKI in LVAD patients was associated with increased 30-day and 1 year mortality.

Considerations for Long-Term Dialysis Access in Patients with Left Ventricular Assist Devices

BACKGROUND

Renal dysfunction, requiring renal replacement therapy (RRT) is commonly encountered in patients with left ventricular assist devices (LVADs). Continuous flow LVAD (CFLVAD) is the most widely used device. Nonpulsatile blood flow begets special hemodynamic changes. This poses a unique challenge in choosing a long-term dialysis access for patients with CFLVAD where life expectancy is limited.

METHODS

A 61-year-old man with an implanted CFLVAD and renal dysfunction receiving intermittent RRT through a nontunneled dialysis catheter had progressed to dialysis-dependent renal failure. He was referred to us for a permanent hemodialysis access.

RESULTS

The patient underwent a right brachio-brachial arterio-venous graft (AVG) placement. The graft was successfully cannulated for hemodialysis on postoperative day 15. On regular follow-up at 18 months, the graft was still functional.

CONCLUSIONS

Dialysis access for patients on LVAD is an exceptional management problem owing to both altered physiology and guarded overall prognosis. We recommend the use of AVG as a convenient and durable option-facilitating early cannulation and expediting freedom from indwelling catheters that may lead to catastrophic consequences. This should limit the need for secondary interventions, hospitalization, and cost, thus improving quality of life.

Post-operative renal failure management in mechanical circulatory support patients

Acute kidney injury (AKI) occurs commonly in patients requiring mechanical circulatory support (MCS) after cardiothoracic surgery. The prognostic implications of AKI in this patient group relate closely to the pathophysiology and risk factors associated with the underlying disease; pre-operative, intra-operative, and post-operative variables; hemodynamic factors; and type of support device used. General approaches to AKI management, including prevention strategies, medical management, and hemodynamic support, are also applicable in patients requiring MCS. Approaches to renal replacement therapy vary depend on patient factors, device-specific factors, and local preferences and experience. In this invited narrative review, we discuss the pathophysiology, risk factors, and prognostic implications of AKI in post-operative adult patients following institution of MCS. Management strategies for AKI are presented with a focus on those supported with either extracorporeal membrane oxygenation or a ventricular assist device.

Biomarkers of Inflammation, Fibrosis, and Acute Kidney Injury in Patients with Heart Failure with and without Left Ventricular Assist Device Implantation

BACKGROUND/AIMS

Renal dysfunction or renal failure is a common complication in left ventricular assist device (LVAD) recipients and is associated with reduced survival. To date, serum creatinine and glomerular filtration rate (GFR) are used for the evaluation of kidney function. However, serum creatinine and GFR have limitations. The objective of our study is to assess the levels of kidney biomarkers in LVAD recipients compared to heart failure patients and healthy controls and to examine their association with conventional clinical biomarkers.

METHODS

The biomarkers neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), plasminogen activator inhibitor-1 (PAI-1), and adiponectin were assessed in 51 participants: 19 heart failure patients, 16 LVAD recipients, and 16 healthy controls. Linear regressions were performed to assess whether demographic and clinical variables predict the levels of biomarkers that are associated with acute kidney injury and the risk of chronic kidney disease.

RESULTS

The levels of NGAL and adiponectin were higher in LVAD recipients and patients with heart failure as compared with healthy controls. The levels of PAI-1 and KIM-1 were not elevated in LVAD recipients. The results of linear regression analysis indicated that when controlling for the effect of CRP and BNP, 40.1% of the variance in NGAL levels can be explained by GFR (R2 = 0.401, F = 5.56, p = 0.005), while CRP can explain 35.3% of the variance in adiponectin levels (R2 = 0.353, F = 4.55, p = 0.01), when controlling for the effect of BNP and GFR.

CONCLUSIONS

The levels of NGAL and adiponectin were augmented in LVAD recipients, suggesting that renal functions were not restored with circulatory support. Larger studies should assess the predictability of these biomarkers of renal dysfunction in LVAD recipients.

Outcomes of Moderate-to-Severe Acute Kidney Injury following Left Ventricular Assist Device Implantation

BACKGROUND

Although acute kidney injury (AKI) is a common complication following cardiac surgery, less is known about the occurrence and consequences of moderate/severe AKI following left ventricular assist device (LVAD) implantation.

METHODS

All patients who had an LVAD implanted at our center from 2008 to 2016 were reviewed to determine the incidence of, and risk factors for, moderate/severe (stage 2/3) AKI and to compare postoperative complications and mortality rates between those with and those without moderate/severe AKI.

RESULTS

Of 246 patients, 68 (28%) developed moderate/severe AKI. A multivariable logistic regression comprising body mass index and prior sternotomy had fair predictive ability (area under the curve = 0.71). A 1-unit increase in body mass index increased the risk of moderate/severe AKI by 7% (odds ratio = 1.07; 95% confidence interval: 1.03-1.11); a prior sternotomy increased the risk more than 3-fold (odds ratio = 3.4; 95% confidence interval: 1.84-6.43). The group of patients with moderate/severe AKI had higher rates of respiratory failure and death than the group of patients with mild/no AKI. Patients with moderate/severe AKI were at 3.2 (95% confidence interval: 1.2-8.2) times the risk of 30-day mortality compared to those without. Even after adjusting for age and Interagency Registry for Mechanically Assisted Circulatory Support profile, those with moderate/severe AKI had 1.75 (95% confidence interval: 1.03-3.0) times the risk of 1-year mortality compared to those without.

DISCUSSION

Risk-stratifying patients prior to LVAD placement in regard to AKI development may be a step toward improving surgical outcomes.

Left Ventricular Assist Devices and the Kidney

Left ventricular assist devices (LVADs) are common and implantation carries risk of AKI. LVADs are used as a bridge to heart transplantation or as destination therapy. Patients with refractory heart failure that develop chronic cardiorenal syndrome and CKD often improve after LVAD placement. Nevertheless, reversibility of CKD is hard to predict. After LVAD placement, significant GFR increases may be followed by a late return to near baseline GFR levels, and in some patients, a decline in GFR. In this review, we discuss changes in GFR after LVAD placement, the incidence of AKI and associated mortality after LVAD placement, the management of AKI requiring RRT, and lastly, we review salient features about cardiorenal syndrome learned from the LVAD experience. In light of the growing number of patients using LVADs as a destination therapy, it is important to understand the effect of these devices on the kidney. Additional research and long-term data are required to better understand the relationship between the LVAD and the kidney.

End-organ recovery post-ventricular assist device can prognosticate survival

BACKGROUND

This study examines our institutional ventricular assist devices (VADs) experience over two decades to understand trends towards predictors of mortality.

METHODS

Retrospective study of patients aged 0-21years supported with a VAD from January 1996 to May 2015. Patient data was examined pre and post-VAD implant among survivors and non-survivors.

RESULTS

Thirty-six patients identified (8 supported by Thoratec® VAD and 28 supported by EXCOR Berlin Heart®). Patient's diagnosis included dilated cardiomyopathy (DCM) (n=19,53%), congenital heart disease (CHD) (n=12,33%), and other (n=5,14%). Median age and body surface area (BSA) were 1.0years[0-7years] and 0.41[0.24-0.92], respectively. Survival to discharge was 75% with no deaths with DCM. The survival rate for patients with CHD was 42%. Univariate analysis showed diagnosis of CHD, smaller BSA and respiratory failure post-implant (Intermacs criteria) as risk factors for mortality. Median duration of VAD support was lower in non-survivors, 14 vs 63days (p=0.03). Renal function at time of transplant or death was normal/pRIFLE Risk category in 20(74%) of survivors and 2(22%) of non-survivors (p=0.06). Post-implant, peak total bilirubin in the first week trended lower in survivors (p=0.06).

CONCLUSIONS

Persistent end-organ impairment in the first 2weeks after VAD placement could be a useful prognostic marker for survival to transplant.

DISPOSITIVOS DE ASSISTÊNCIA VENTRICULAR E CUIDADOS DE ENFERMAGEM

RESUMO Objetivo: descrever o funcionamento, os benefícios e as complicações associadas ao uso de dispositivos de assistência ventricular e identificar as intervenções realizadas por enfermeiros no cuidado ao paciente com este dispositivo, de acordo com as evidências. Método: revisão integrativa, com artigos coletados em bases de dados da saúde, em fevereiro de 2015. Os descritores utilizados foram heart diseases, heart-assist devices e nursing. Identificaram-se 34 artigos, os quais foram submetidos à análise temática. Resultados: os dispositivos de assistência ventricular funcionam como bombas mecânicas promotoras de débito cardíaco adequado. Seu principal benefício é a estabilização hemodinâmica. A complicação mais comum é a infecção. Educação em saúde, suporte emocional, cuidados com sítio de saída e realização de curativo são os principais cuidados realizados por enfermeiros. Conclusão: as evidências comprovam a melhoria da sobrevida de pacientes com insuficiência cardíaca grave com o uso dos dispositivos de assistência ventricular, reiterando a importância da ampliação dessa tecnologia no Brasil como possibilidade de tratamento.

Renal dysfunction and chronic mechanical circulatory support: from patient selection to long-term management and prognosis

PURPOSE OF REVIEW

The purpose of this review is to describe the effects of mechanical circulatory support (MCS) on changes in kidney function and their relationship with mortality, with an additional focus on the evaluation and management of both preimplant and post-MCS renal dysfunction.

RECENT FINDINGS

Renal dysfunction is highly prevalent in patients referred for MCS and is associated with significantly increased mortality and postoperative acute kidney injury. Most patients, including those with renal dysfunction, experience marked early improvement in renal function with MCS, likely secondary to correction of the cardiogenic shock, volume overload, and neurohormonal activation characteristic of advanced heart failure. Currently, there are no diagnostic tests to definitively distinguish reversible forms of renal dysfunction likely to improve with MCS from irreversible renal dysfunction. Furthermore, the characteristic improvements in renal function observed in the early months of MCS are often transient, with subsequent recurrence of renal dysfunction with longer durations of support. Venous congestion, right ventricular dysfunction, and reduced pulsatility are potential mechanisms involved in resurgence of renal dysfunction following MCS.

SUMMARY

With the exponential growth of MCS, research endeavors to both improve understanding of the mechanisms behind observed changes in renal function and elucidate the device-related effects on the kidney are imperative.

Variability in inpatient serum creatinine: its impact upon short- and long-term mortality

BACKGROUND

Long-staying medical inpatients carry a significant burden of acute and chronic illness. Prediction of their in-hospital and longer-term mortality risk is important.

AIM

The aim of this study was to determine to what extent creatinine variability predicts in-hospital and 1-year mortality in inpatients.

DESIGN

Retrospective cohort analysis.

METHODS

Patients were included if aged 18 years or older and if admitted for 7 days or longer. The main outcome variables were mortality in hospital and after discharge.

RESULTS

Increasing age, the presence of heart failure and a reduced estimated glomerular filtration rate (eGFR) on admission (<60 ml/min/1.73 m(2)) all associated with death risk (both in hospital and within a year of discharge). The creatinine change was related to mortality risk for the patient whilst in hospital and within 1 year after discharge independently of these other factors. The threshold of creatinine change, above which the in-hospital mortality rose significantly was 25 µmol/l (P < 0.001). A creatinine change of >10 µmol/l predicted significantly higher mortality within a year of discharge (P < 0.001). Every 5 µmol/l change in creatinine was associated with an in-hospital mortality increase of 3% (P < 0.001) and a 1-year mortality increase of 1% (P < 0.007).

CONCLUSIONS

Patients with a creatinine rise or fall of >10 µmol/l during admission are at higher risk of death after discharge than those with more stable creatinine. These patients therefore merit further attention that might include more focused nutritional assessment, cardiovascular risk factor management or advance care planning.