End-organ function in patients on long-term circulatory support with continuous- or pulsatile-flow assist devices

Hemodynamic Predictors of Renal Function After Pediatric Left Ventricular Assist Device Implantation

Although renal function often improves after pediatric left ventricular assist device (LVAD) implantation, recovery is inconsistent. We aimed to identify hemodynamic parameters associated with improved renal function after pediatric LVAD placement. A single-center retrospective cohort study was conducted in patients less than 21 years who underwent LVAD placement between June 2004 and December 2015. The relationship between hemodynamic parameters and estimated glomerular filtration rate (eGFR) was assessed using univariate and multivariate modeling. Among 54 patients, higher preoperative central venous pressure (CVP) was associated with eGFR improvement after implantation (p = 0.012). However, 48 hours postimplantation, an increase in CVP from baseline was associated with eGFR decline over time (p = 0.01). In subgroup analysis, these associations were significant only for those with normal pre-ventricular assist device renal function (p = 0.026). In patients with preexisting renal dysfunction, higher absolute CVP values 48 and 72 hours after implantation predicted better renal outcome (p = 0.005). Our results illustrate a complex relationship between ventricular function, volume status, and renal function. Additionally, they highlight the challenge of using CVP to guide management of renal dysfunction in pediatric heart failure. Better methods for evaluating right heart function and volume status are needed to improve our understanding of how hemodynamics impact renal function in this population.

Designing an Active Valvulated Outflow Conduit for a Continuous-Flow Left Ventricular Assist Device to Increase Pulsatility: A Simulation Study

The purpose of this work was to investigate, using a lumped parameter model, the feasibility of increasing the pulsatility of a continuous-flow ventricular assist device (VAD) by implanting an active valvulated outflow cannula. A lumped parameter model was adopted for this study. VAD was modeled, starting from its pressure-flow characteristics. The valvulated outflow conduit was modeled as an active resistance described by a square function. Starting from pathologic condition, the following simulations were performed: VAD, VAD and valvulated outflow conduit in copulsation and counterpulsation with different ratios between the VAD valve opening rate and the heart rate, and asynchrony work with the heart with different VAD valve opening intervals. The copulsation 1:1 configuration and the asynchrony 0.3s-close-0.7s-open configurations permit to maximize the hemodynamic benefits provided by the presence of the active VAD outflow valvulated conduit providing an increase of arterial pulsatility from 1.86% to 14.98% without the presence of left ventricular output. The presence of the active VAD valve in the outflow conduit causes a decrement of the left ventricular unloading and of VAD flow and, that can be counteracted by increasing the VAD speed without affecting arterial pulsatility. The valvulated outflow tube provides an increase in arterial pulsatility; it can be driven in different working modality and can be potentially applicable to all types of VADs. However, the valvulated outflow conduit causes a decrement of left ventricular unloading and of the VAD flow that can be counteracted, increasing the VAD speed.

First Successful Organ Procurement From a Pediatric Patient With a Nonpulsatile Ventricular Assist Device

Left ventricular assist devices have become an important therapeutic option as a mechanical circulatory support system in the treatment of end-stage heart failure. Organ transplants from brain dead donors on mechanical circulatory support are rare. In the literature, many successful solid-organ transplants have been reported using these donors. However, to our knowledge, this is the first report of successful solid-organ transplant from a child donor with a nonpulsatile ventricular assist device.

Increasing the pulsatility of continuos flow VAD: comparison between a valvulated outflow cannula and speed modulation by simulation

To investigate by a lumped parameter model the feasibility of increasing the pulsatility of a continuous flow VAD, implanting an active valvulated outflow cannula and to compare the results with the haemodynamic outcome given by speed modulation methods. The concomitant presence of speed modulation and the active valvulated outflow conduit is also simulated. A lumped parameter model was adopted. VAD was modeled starting from its pressure flow characteristics with a second order polynomial equation. The valvulated outflow conduit was modeled as an active resistance described by a square function. Starting from pathological condition we simulated: VAD; VAD and valvulated outflow conduit in copulsation, counterpulsation and asynchrony work with the heart; VAD and active valvulated outflow tube and speed modulation. Copulsation 1:1 and asynchrony 0.3 s valve close-0.7 s valve open configurations maximised the haemodynamic benefits with the highest increment in pulsatility. The valvulated outflow conduit causes a decrement of the left ventricular unloading and of VAD flow that can be counteracted by increasing the VAD speed without affecting pulsatility. The concomitant use of the speed modulation and the active valvulated outflow conduit can further increase the pulsatility without altering left ventricular unloading and VAD flow. The valvulated outflow tube provide similar increase in pulsatility to speed modulation method but causes a decrement of left ventricular unloading and VAD flow that can be counteracted increasing the VAD speed or allowing a partial support. A valvulated outflow tube can be potentially applied to all continuous flow VADs.

Acute kidney injury following left ventricular assist device implantation: Contemporary insights and future perspectives

Currently, an increasing number of patients with end-stage heart failure are being treated with left ventricular assist device (LVAD) therapy as bridge-to-transplantation, bridge-to-candidacy, or destination therapy (DT). Potential life-threatening complications may occur, specifically in the early post-operative phase, which positions LVAD implantation as a high-risk surgical procedure. Acute kidney injury (AKI) is a frequently observed complication after LVAD implantation and is associated with high morbidity and mortality. The rapidly growing number of LVAD implantations necessitates better approaches of identifying high-risk patients, optimizing peri-operative management, and preventing severe complications such as AKI. This holds especially true for those patients receiving an LVAD as DT, who are typically older (with higher burden of comorbidities) with impaired renal function and at increased post-operative risk. Herein we outline the definition, diagnosis, frequency, pathophysiology, and risk factors for AKI in patients with an LVAD. We also review possible strategies to prevent and manage AKI in this patient population.

Pulmonary function assessment post-left ventricular assist device implantation

Aim

The lungs—and particularly the alveolar‐capillary membrane—may be sensitive to continuous flow (CF) and pulmonary pressure alterations in heart failure (HF). We aimed to investigate long‐term effects of CF pumps on respiratory function.

Methods and results

We conducted a retrospective study of patients with end‐stage HF at our institution. We analysed pulmonary function tests [e.g. forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁)] and diffusing capacity of the lung for carbon monoxide (D_LCO) from before and after left ventricular assist device (LVAD) implantation and compared them with invasive haemodynamic studies. Of the 274 patients screened, final study analysis involved 44 patients with end‐stage HF who had CF LVAD implantation between 1 February 2007 and 31 December 2015 at our institution. These patients [mean (standard deviation, SD) age, 50 (9) years; male sex, n = 33, 75%] received either the HeartMate II (Thoratec Corp.) pump (77%) or the HeartWare (HeartWare International Inc.) pump. The mean (SD) left ventricular ejection fraction was 21% (13%). At a median of 237 days post‐LVAD implantation, we observed significant D_LCO decrease (−23%) since pre‐implantation (P < 0.001). ΔD_LCO had an inverse relationship with changes in pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP) from pre‐LVAD to post‐LVAD implantation: ΔD_LCO to ΔPCWP (r = 0.50, P < 0.01) and ΔD_LCO to ΔRAP (r = 0.39, P < 0.05). We observed other reductions in FEV₁, FVC, and FEV₁/FVC between pre‐LVAD and post‐LVAD implantation. In mean (SD) values, FEV₁ changed from 2.3 (0.7) to 2.1 (0.7) (P = 0.005); FVC decreased from 3.2 (0.8) to 2.9 (0.9) (P = 0.01); and FEV₁/FVC went from 0.72 (0.1) to 0.72 (0.1) (P = 0.50). Landmark survival analysis revealed that ΔD_LCO from 6 months after LVAD implantation was predictive of death for HF patients [hazard ratio (95% confidence interval), 0.60 (0.28–0.98); P = 0.03].

Conclusions

Pulmonary function did not improve after LVAD implantation. The degree of D_LCO deterioration is related to haemodynamic status post‐LVAD implantation. The ΔD_LCO within 6 months post‐operative was associated with survival.

Changes in renal function after left ventricular assist device placement in pediatric patients: A Pedimacs analysis

BACKGROUND

Renal dysfunction (RD) is prevalent among pediatric patients with advanced heart failure. Data are limited regarding changes in renal function after left ventricular assist device (LVAD) placement in this population.

METHODS

Pediatric LVAD recipients enrolled in the Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) between September 19, 2012 and June 30, 2016 were included. Longitudinal changes in renal function were analyzed for the entire cohort as well as subgroups stratified by patient and device characteristics. Logistic regression was used to attempt to identify factors associated with lack of improvement in renal function after LVAD placement. Post-LVAD outcomes were assessed using the Kaplan‒Meier method.

RESULTS

Data from 247 patients from 39 centers were analyzed. Baseline RD (estimated glomerular filtration rate [eGFR] <90 ml/min/1.73 m²) was present in 150 (61%) patients. Overall, eGFR improved post-LVAD, peaking at 1 month post-implant. There was an inverse relationship between baseline eGFR and the degree of improvement at 1 month. Degree of improvement in eGFR at 1 month was not impacted by device type, age, Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile, or diagnosis. Failure to normalize renal function at 1 week was correlated with persistent RD at 1 month. Post-implant outcomes did not differ among patients stratified by pre-implant renal function.

CONCLUSIONS

Renal function improves post-LVAD placement in pediatric patients regardless of age, diagnosis, illness severity, or device type, with improvement most pronounced in patients with baseline RD. Identifying patients with irreversible renal dysfunction before LVAD placement remains difficult. Pre-LVAD renal function does not appear to impact survival to transplant.

The influence of less invasive ventricular assist device implantation on renal function

BACKGROUND

End-stage heart failure is associated with severe after-effects such as heart valve insufficiency, cardiac arrhythmias or end-organ dysfunctions. Renal failure or 'cardiorenal syndrome' is a critical end-organ disorder associated with advanced heart failure, which occurs due to low-output failure. Drug therapy or surgical interventions involving left ventricular assist device (LVAD) implantation may impede the progress of heart insufficiency and its after-effects including renal failure. In this study, we investigated the impact of a minimally invasive ventricular assist device implantation through upper hemisternotomy combined with anterolateral thoracotomy on renal function, in patients with perioperative renal failure.

METHODS

We analyzed data obtained from 103 patients (80 males, 23 females; mean age 53.8±11.7) who underwent LVAD implantation at our clinic within a 15-year interval (2001-2016) and were dialyzed due to renal dysfunction. 90 patients were operated with the conventional LVAD implantation technique (standard approach surgery, SAS) and 13 underwent less invasive approach implantation (less invasive surgery, LIS).

RESULTS

For all patients, data analysis showed significant increase of glomerular filtration rate (GFR) (44.2±56.48 mL/min; 95% CI: 33.81-55.28; P<0.001) along with a significant decrease in the levels of creatinine (-1.08±1.83 mg/dL; 95% CI: 0.75-1.46; P<0.001) and urea (-4.62±13.66 mmol/L; 95% CI: 1.95-7.29; P<0.001). There was a considerable difference in change of renal parameters in patients treated with LIS in comparison to patients who underwent SAS, which was however not statistically significant (GFR: P=0.494; creatinine: P=0.543; urea P=0.918).

CONCLUSIONS

LVAD implantation improves kidney function in patients with renal dysfunction. A considerable difference in the change of renal parameters was detected in patients with LIS as compared to SAS, which was not significant possibly due to the limited size of the patient cohort (n=13).

Left Atrial Pressure Monitoring With an Implantable Wireless Pressure Sensor After Implantation of a Left Ventricular Assist Device

After implantation of a continuous-flow left ventricular assist device (LVAD), left atrial pressure (LAP) monitoring allows for the precise management of intravascular volume, inotropic therapy, and pump speed. In this case series of 4 LVAD recipients, we report the first clinical use of this wireless pressure sensor for the long-term monitoring of LAP during LVAD support. A wireless microelectromechanical system pressure sensor (Titan, ISS Inc., Ypsilanti, MI) was placed in the left atrium in four patients at the time of LVAD implantation. Titan sensor LAP was measured in all four patients on the intensive care unit and in three patients at home. Ramped speed tests were performed using LAP and echocardiography in three patients. The left ventricular end-diastolic diameter (cm), flow (L/min), power consumption (W), and blood pressure (mm Hg) were measured at each step. Measurements were performed over 36, 84, 137, and 180 days, respectively. The three discharged patients had equipment at home and were able to perform daily recordings. There were significant correlations between sensor pressure and pump speed, LV and LA size and pulmonary capillary wedge pressure, respectively (r = 0.92-0.99, p < 0.05). There was no device failure, and there were no adverse consequences of its use.

Initial Results of Clinical Trial with a New Left Ventricular Assist Device (LVAD) Providing Synchronous Pulsatile Flow

Objectives

A multicentric European Clinical Study is ongoing to evaluate safety and efficacy of a new pulsatile implantable LVAD (BestBeat), smaller and lighter than similar devices, capable of providing synchronous and counterpulsating flow with respect to the LV of end-stage heart failure patients. Preliminary clinical results are reported.

Methods

The new BestBeat LVAD was used, consisting of an implantable pulsatile blood pump, electromechanically driven by a ball screw mechanism, and a wearable electronic controller and power sources. The clinical trial was conducted at 5 European centers. Adult patients affected by CHF in NYHA Class IV despite optimized medical treatment were enrolled. The primary study endpoint was survival at 90 days. Further study endpoints were maintenance of adequate LVAD pump flow and a minimum rate of adverse events during support.

Results

As of June 2008, 6 patients received the implant. Cumulative support time was 3.7 years, median support time 176 days. All patients who completed the study survived except for one, who died after 48 days, due to combined infection and cerebrovascular accident. Another two patients died: one from intracranial bleeding 113 days after implant, and one from septic shock after 123 days. Hemodynamic improvement with Cl>2.0 l/min/m2 and recovery of end-organ function expressed by consistent improvement of BUN, creatinine and bilirubin were reached in all patients. No device failure was observed. There was no bleeding requiring re-exploration, no hemolysis and only two device-related infections (both in one patient). Neurologic events were reported, the most serious ones occurring in patients with pre-implant respiratory and kidney failure. Three patients were discharged home. Two patients were successfully transplanted, one after 6 months and one after 13 months on device.

Conclusions

Good performance and efficacy of the device were observed; the endpoints of the study were achieved, and its safety was consistent with expectations. The ongoing study will allow further conclusions to be drawn.

Improved identification of the electrocardio-signal for pulsatile ventricular assist devices

We introduce and investigate a method to identify the feature point of an electrocardiogram (ECG) to provide real-time and accurate trigger signals for pulsatile ventricular assist devices (PVADs). An important part of this method is an improved data processing algorithm, in which a differential calculator and another a low-pass filtering were added to avoid drift in the original signal and systematically delay caused by physical devices. The method was systematically illustrated in this article and a test-setup was built based on the LabVIEW program development environment. Both simulations and experiments were carried out to demonstrate the merits of the method. Simulated results based on four typical pathological ECG signals confirm the robustness and adaptability of this method. Experimental results verified the benefits of this method with regard to increased accuracy that can pick up the interested signal accurately in a degree of larger than 99%. This improved technology proposed in this research will be greatly beneficial to simultaneous triggering in VADs and eventually to the heart failure recovery.

Effects of Left Ventricular Assist Device Support on End-Organ Function in Patients With Heart Failure: Comparison of Pulsatile- and Continuous-Flow Support in a Single-Center Experience

BACKGROUND

Limited data exist about the effects of continuous-flow versus pulsatile-flow left ventricular assist devices (LVADs) on end-organ function. We hypothesized that a pulsatile Polvad MEV (PM) would result in outcomes similar to those of similarly ill patients implanted with a continuous-flow LVAD (Heartware [HW] or Heartmate II [HMII]). We aimed to compare renal, hepatic, and hematologic functions in the 1st 30 days of support.

METHODS

We retrospectively reviewed patients with 24 PM (21 M, 3 F; group P) and 15 HW and 5 HMII (20 M, 0 F); group C LVAD implantations from April 2007 to February 2014. Creatinine, bilirubin, aspartate (AST) and alanine (ALT) transaminases, hematocrit, platelet count, international normalized ratio (INR), and activated partial thromboplastin time (APTT) parameters were analyzed before implantation and during 30 days of support. Demographic parameters were similar.

RESULTS

No significant differences were found between the groups regarding baseline renal, hepatic, or hematologic function. Baseline INR and APTT were significantly higher in group P. Levels of creatinine were similar between groups. They increased from baseline to postoperative day (POD) 1 and then decreased. Bilirubin levels were insignificantly higher in group P. Transaminases were significantly higher in group P (AST in PODs 3-6, ALT in PODs 3-7). INR values were significantly higher at baseline and in POD 0. APTT values were insignificantly higher in group P.

CONCLUSIONS

The use of LVAD improved renal and hepatic function in our series. Patients in group P had more decreased hepatic function and presented slower regeneration.

Comparison of Mechanical Circulatory Support by the Use of Pulsatile Left Ventricular Assist Devices Polvad MEV and Continuous Flow Heart Ware and Heart Mate II in a Single-Center Experience

BACKGROUND

Mechanical circulatory support is increasingly used in patients with heart failure as a bridge to transplant or recovery. Results of use the Polish POLVAD MEV pulsatile circulatory support system and its comparison with novel devices never was done. We compared the course of patients with left ventricular circulatory support (left ventricular assist device [LVAD]) supported by POLVAD MEV or continuous flow devices Heart Mate II (HM II) and Heart Ware (HW) in single-center cohort.

METHODS

We retrospectively reviewed 44 patients who underwent Polvad Mev (group P; n = 24 [21M/3F]) or HW or HM II (group C; n = 20 [20M/0F]) implantation between April 2007 and February 2014. Patients were in INTERMACS 1 (6 in group P and 1 in group C) or 2. Preimplant demographics, and perioperative and postoperative clinical outcomes were reviewed between groups. We analyzed baseline signs of heart failure, comorbidities, complications, and the 30- and 90-day results.

RESULTS

Among the groups, age, gender, weight, and cause of heart failure were comparable. Patients in group C suffered more frequently from hypercholesterolemia preoperatively. Patients in group P had more pulmonary complications (7 vs 0) after LVAD implantation and stay longer on intensive care unit than patients in group C (17.61 ± 16.96 vs 9.56 ± 9.42; P = .047). After exclusion, INTERMACS 1 patients it was not significant (14.8 ± 10.8 vs 9.8 ± 9.6 days; P = .065), the 30- and 90-day mortality was comparable.

CONCLUSIONS

Implantation of pulsatile POLVAD MEV and continuous flow devices as LVAD support provides comparable results. A greater number of complications in group P can cause increased mortality over a longer observation period.

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.

Current Status of Left Ventricular Assist Device Therapy

Congestive heart failure (HF) remains a serious burden in the Western World. Despite advances in pharmacotherapy and resynchronization, many patients have progression to end-stage HF. These patients may be candidates for heart transplant or left ventricular assist device (LVAD) therapy. Heart transplants are limited by organ shortages and in some cases by patient comorbidities; therefore, LVAD therapy is emerging as a strategy of bridge to transplant or as a destination therapy in patients ineligible for transplant. Patients initially ineligible for a transplant may, in certain cases, become eligible for transplant after physiologic improvement with LVAD therapy, and a small number of patients with an LVAD may have sufficient recovery of myocardial function to allow device explantation. This clinically oriented review will describe (1) the most frequently used pump types and aspects of the continuous-flow physiology and (2) the clinical indications for and the shift toward the use of LVADs in less sick patients with HF. Additionally, we review complications of LVAD therapy and project future directions in this field. We referred to the Interagency Registry for Mechanically Assisted Circulatory Support, landmark trials, and results from recently published studies as major sources in obtaining recent outcomes, and we searched for related published literature via PubMed. This review focuses primarily on clinical practice for primary care physicians and non-HF cardiologists in the United States.

Physiologic effects of continuous-flow left ventricular assist devices

BACKGROUND

Within the past 10 years, continuous-flow left ventricular assist devices (LVADs) have replaced pulsatile-flow LVADs as the standard of care for both destination therapy and bridging patients to heart transplantation. Despite the rapid clinical adoption of continuous-flow LVADs, an understanding of the effects of continuous-flow physiology, as opposed to more natural pulsatile-flow physiology, is still evolving.

MATERIALS AND METHODS

A thorough review of the relevant scientific literature regarding the physiological and clinical effects of continuous-flow physiology was performed. These effects were analyzed on an organ system basis and include an evaluation of the cardiovascular, respiratory, hematologic, gastrointestinal, renal, hepatic, neurologic, immunologic, and endocrine systems.

RESULTS

Continuous-flow physiology is, generally speaking, well tolerated over the long term. However, several changes are manifest at the organ system level. Although many of these changes are without appreciable clinical significance, other changes, such as an increased rate of gastrointestinal bleeding, appear to be associated with continuous-flow physiology.

CONCLUSIONS

Continuous-flow LVADs confer a significant advantage over their pulsatile-flow counterparts with regard to size and durability. From a physiological standpoint, continuous-flow physiology has limited clinical effects at the organ system level. Although improved over previous generations, challenges with this technology remain. Approaching these problems with a combination of clinical and engineering solutions may be needed to achieve continued progression in the field of durable mechanical circulatory support.

New therapy, new challenges: The effects of long-term continuous flow left ventricular assist device on inflammation

Surgically implanted continuous flow left ventricular assist devices (CF-LVADs) are currently used in patients with end-stage heart failure (HF). However, CF-LVAD therapy introduces a new set of complications and adverse events in these patients. Major adverse events with the CF-LVAD include right heart failure, vascular dysfunction, stroke, hepatic failure, and multi-organ failure, complications that may have inflammation as a common etiology. Our aim was to review the current evidence showing a relationship between these adverse events and elevated levels of inflammatory biomarkers in CF-LVAD recipients.

Biventricular mechanical support devices--clinical perspectives

Cardiac transplantation remains the optimal treatment for end stage heart failure in selected patients. However, the shortage of donor hearts, rigorous eligibility criteria and long waiting lists have increased the demand for alternative treatment strategies such as mechanical circulatory support. While many patients are adequately supported with left ventricular assist devices, frequently there is right heart failure or involvement of the right ventricle, requiring biventricular support. Pulsatile flow biventricular devices and total artificial hearts approved for temporary biventricular support have limitations including size, high rates of adverse events and restricted mobility which makes them unsuitable for long term support. A number of centres have reported dual continuous flow left ventricular assist devices as a means of supporting the left and right heart. This review will summarise the literature on the outcomes and complications from current biventricular support devices and assess the role of dual continuous flow VAD therapy, and the new continuous flow total heart replacement devices.

Multiple Beneficial Effects of Balloon Pulmonary Angioplasty in Patients With Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Pulmonary arterial hypertension with systemic dysfunctions, including metabolic disorders and renal dysfunction, has a poor prognosis. However, it remains to be elucidated whether chronic thromboembolic pulmonary hypertension (CTEPH) is also associated with systemic dysfunctions, and if so, whether balloon pulmonary angioplasty (BPA) improves them.

METHODS AND RESULTS

Fifty-five consecutive patients who underwent BPA from March 2012 to December 2014 for systemic dysfunctions, including glycemic control, lipid profiles, renal and vascular function, and nutritional status were examined. The analyses were performed before and after BPA (mean, 3.5 sessions/patient) and changes in hemodynamic parameters were compared. The average follow-up period was 474±245 days. Baseline prevalence of hypertension, diabetes mellitus, dyslipidemia and advanced chronic kidney disease was 58, 7, 33 and 36%, respectively. BPA caused marked hemodynamic improvements in the CTEPH patients. Importantly, BPA also significantly improved dysglycemia (fasting blood sugar, hemoglobin A1c and homeostatic assessment model of insulin resistance), renal (creatinine and estimated glomerular filtration rate) and vascular (cardio-ankle vascular index) functions and nutritional status (albumin, cholesterols, and body mass index). Importantly, there were positive correlations between the degrees of the hemodynamic improvements and those of other improvements.

CONCLUSIONS

These results indicate that BPA may exert multiple beneficial effects in CTEPH patients, not only in terms of hemodynamics but also in other systemic functions, with positive correlations among them.

Physiological impact of continuous flow on end-organ function: clinical implications in the current era of left ventricular assist devices

The clinical era of continuous-flow left ventricular assist devices has debunked many myths about the dire need of a pulse for human existence. While this therapy has been documented to provide a clear survival benefit in end-stage heart failure patients, we are now faced with certain morbidity challenges that as of yet have no easy mechanistic physiological explanation. The effect of physiological changes on end-organ function in patients supported by continuous-flow ventricular assist devices may offer insight into some of these morbidities. We therefore present a review of current evidence documenting the impact of continuous flow on end-organ function.

Impact of ventricular assist device placement on longitudinal renal function in children with end-stage heart failure

BACKGROUND

Although ventricular assist devices (VADs) restore hemodynamics in those with heart failure, reversibility of end-organ dysfunction with VAD support is not well characterized. Renal function often improves in adults after VAD placement, but this has not been comprehensively explored in children.

METHODS

Sixty-three children on VAD support were studied. Acute kidney injury (AKI) was defined by Kidney Disease: Improving Global Outcomes criteria. Estimated glomerular filtration rate (eGFR) was determined by the Schwartz method. Generalized linear mixed-effects models compared the pre-VAD and post-VAD eGFR for the cohort and sub-groups with and without pre-VAD renal dysfunction (pre-VAD eGFR < 90 ml/min/1.73 m(2)).

RESULTS

The pre-VAD eGFR across the cohort was 84.0 ml/min/1.73 m(2) (interquartile range [IQR] 62.3-122.7), and 55.6% (34 of 63) had pre-VAD renal dysfunction. AKI affected 60.3% (38 of 63), with similar rates in those with and without pre-existing renal dysfunction. Within the cohort, the nadir eGFR occurred 1 day post-operatively (62.9 ml/min/1.73 m(2); IQR, 51.2-88.9 ml/min/1.73 m(2); p < 0.001). By Day 5, however, the eGFR exceeded the baseline (99.0 ml/min/1.73 m(2); IQR, 59.3-146.7 ml/min/1.73 m(2); p = 0.03) and remained significantly higher through the first post-operative week. After adjusting for age, gender, and AKI, the eGFR continued to increase throughout the entire 180-day study period (β = 0.0025; 95% confidence interval, 0.0015-0.0036; p < 0.001). Patients with pre-VAD renal dysfunction experienced the greatest improvement in the eGFR (β = 0.0051 vs β = 0.0013, p < 0.001).

CONCLUSIONS

Renal dysfunction is prevalent in children with heart failure undergoing VAD placement. Although peri-operative AKI is common, renal function improves substantially in the first post-operative week and for months thereafter. This is particularly pronounced in those with pre-VAD renal impairment, suggesting that VADs may facilitate recovery and maintenance of kidney function in children with advanced heart failure.

Left ventricular assist devices: a kidney's perspective

The left ventricular assist device (LVAD) has become an established treatment option for patients with refractory heart failure. Many of these patients experience chronic kidney disease (CKD) due to chronic cardiorenal syndrome type II, which is often alleviated quickly following LVAD implantation. Nevertheless, reversibility of CKD remains difficult to predict. Interestingly, initial recovery of GFR appears to be transient, being followed by gradual but significant late decline. Nevertheless, GFR often remains elevated compared to preimplant status. Larger GFR increases are followed by a proportionally larger late decline. Several explanations for this gradual decline in renal function after LVAD therapy have been proposed, yet a definitive answer remains elusive. Mortality predictors of LVAD implantation are the occurrence of either postimplantation acute kidney injury (AKI) or preimplant CKD. However, patient outcomes continue to improve as LVAD therapy becomes more widespread, and adverse events including AKI appear to decline. In light of a growing destination therapy population, it is important to understand the cumulative effects of long-term LVAD support on kidney function. Additional research and passage of time are required to further unravel the intricate relationships between the LVAD and the kidney.

Why pulsatility still matters: a review of current knowledge

Continuous-flow left ventricular assist devices (LVAD) have become standard therapy option for patients with advanced heart failure. They offer several advantages over previously used pulsatile-flow LVADs, including improved durability, less surgical trauma, higher energy efficiency, and lower thrombogenicity. These benefits translate into better survival, lower frequency of adverse events, improved quality of life, and higher functional capacity of patients. However, mounting evidence shows unanticipated consequences of continuous-flow support, such as acquired aortic valve insufficiency and acquired von Willebrand syndrome. In this review article we discuss current evidence on differences between continuous and pulsatile mechanical circulatory support, with a focus on clinical implications and potential benefits of pulsatile flow.

Kidney dysfunction and left ventricular assist device support: a comprehensive perioperative review

Left ventricular assist devices (LVADs) are used increasingly as a bridge to transplantation or as destination therapy in end-stage heart failure patients who do not respond to optimal medical therapy. Many of these patients have end-organ dysfunction, including advanced kidney dysfunction, before and after LVAD implantation. Kidney dysfunction is a marker of adverse outcomes, such as increased morbidity and mortality. This review discusses kidney dysfunction and associated management strategies during the dynamic perioperative time period of LVAD implantation. Furthermore, we suggest potential future research directions to better understand the complex relationship between renal pathophysiology and mechanical circulatory support.

Comparison of continuous-flow and pulsatile-flow left ventricular assist devices: is there an advantage to pulsatility?

BACKGROUND

Continuous-flow left ventricular assist devices (CFVAD) are currently the most widely used type of mechanical circulatory support as bridge-to-transplant and destination therapy for end-stage congestive heart failure (HF). Compared to the first generation pulsatile-flow left ventricular assist devices (PFVADs), CFVADs have demonstrated improved reliability and durability. However, CFVADs have also been associated with certain complications thought to be linked with decreased arterial pulsatility. Previous studies comparing CFVADs and PFVADs have presented conflicting results. It is important to understand the outcome differences between CFVAD and PFVAD in order to further advance the current VAD technology.

METHODS

In this review, we compared the outcomes of CFVADs and PFVADs and examined the need for arterial pulsatility for the future generation of mechanical circulatory support.

RESULTS

CVADs offer advantages of smaller size, increased reliability and durability, and subsequent improvements in survival. However, with the increasing duration of long-term support, it appears that CFVADs may have specific complications and a lower rate of left ventricular recovery associated with diminished pulsatility, increased pressure gradients on the aortic valve and decreased compliance in smaller arterial vessels. PFVAD support or pulsatility control algorithms in CFVADs could be beneficial and potentially necessary for long term support.

CONCLUSIONS

Given the relative advantages and disadvantages of CFVADs and PFVADs, the ultimate solution may lie in incorporating pulsatility into current and emerging CFVADs whilst retaining their existing benefits. Future studies examining physiologic responses, end-organ function and LV remodeling at varying degrees of pulsatility and device support levels are needed.

Spectroscopic and morphological characterization of inflow cannulas of left ventricular assist devices

Despite the consistent clinical data on the positive effects of left ventricular assist devices (LVADs) in the treatment of refractory heart failure, unfortunately these devices yet show some limitations such as the risk of stroke, infection, and device malfunction. The complex interplay between blood and the foreign material has a major role in the occurrence of these complications and biocompatibility of the inflow cannula would be pivotal in these terms. In this study, we carried out an in-depth physicochemical characterization of two commercially available LVADs by means of field emission gun scanning electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectra. Our results show that, despite both pumps share the same physicochemical concepts, major differences can be identified in the surface nature, morphology, and chemical composition of their inflow cannulas.

Physiologic and hematologic concerns of rotary blood pumps: what needs to be improved?

Over the past few decades, advances in ventricular assist device (VAD) technology have provided a promising therapeutic strategy to treat heart failure patients. Despite the improved performance and encouraging clinical outcomes of the new generation of VADs based on rotary blood pumps (RBPs), their physiologic and hematologic effects are controversial. Currently, clinically available RBPs run at constant speed, which results in limited control over cardiac workload and introduces blood flow with reduced pulsatility into the circulation. In this review, we first provide an update on the new challenges of mechanical circulatory support using rotary pumps including blood trauma, increased non-surgical bleeding rate, limited cardiac unloading, vascular malformations, end-organ function, and aortic valve insufficiency. Since the non-physiologic flow characteristic of these devices is one of the main subjects of scientific debate in the literature, we next emphasize the latest research regarding the development of a pulsatile RBP. Finally, we offer an outlook for future research in the field.

Evolution of renal function after partial and full mechanical support for chronic heart failure

PURPOSE

Recently a minimal invasive, partial support continuous flow left ventricular assist device (LVAD) became available for treatment of chronic heart failure. The aim of this study was to analyze whether partial support is capable of improving kidney function in end-stage heart failure.

METHODS

We performed a single-center retrospective analysis of patients how received a full (n = 43) or partial support LVAD (n = 18) between 2007 and 2013. Patients on dialysis or in INTERMACS class I were excluded. Renal function was assessed until 3 months after the implantation. A calculated GFR less than 60 m/min was considered to be renal failure.

RESULTS

Creatinine level after LVAD implant decreased 23% in patients on full support (1.3 ± 0.4 mg/dl vs. 1.0 ± 0.3 mg/dl; p<0.001) and 24% in patients on partial support (1.6 ± 0.6 mg/dl vs. 1.2 ± 0.4 mg/dl; p = 0.17) within 3 months. In each group patients with a preoperative GFR less than 60 ml/min were selected. In this subgroup there was a 35% decrease in creatinine levels for patients on full support (1.7 ± 0.4 mg/dl vs. 1.1 ± 0.5 mg/dl; p<0.01) and a 32% decrease in patients on partial support (2 ± 0.4 mg/dl vs. 1.4 ± 0.3 mg/dl; p<0.05) at 3 months.

CONCLUSIONS

We observed a significant improvement in renal function in patients supported by full or partial support devices, even if the preoperative renal function was severly impaired. The use of diuretics decreased in both groups. In chronic heart failure patients with impaired renal function, partial support is sufficient to improve renal function significantly.

Long-term outcome of patients on continuous-flow left ventricular assist device support

OBJECTIVES

Recent advances in technology and improved patient management have enabled the use of mechanical circulatory support for unexpected long-term periods. Improved long-term outcomes may facilitate the use of device therapy as an alternative to heart transplantation. However, there are scarce data about the long-term outcomes of continuous-flow left ventricular assist devices. This study sought to evaluate the long-term outcomes in patients receiving continuous-flow left ventricular assist devices.

METHODS

Between March 2004 and June 2010, 140 patients underwent continuous-flow left ventricular assist device insertion as a bridge to transplantation or a destination therapy. These patients' charts were retrospectively reviewed.

RESULTS

The initial strategy for continuous-flow left ventricular assist device therapy was bridge to transplantation in 115 patients (82%) and destination therapy in 25 patients (18%). Of those, 24 (17%) died on left ventricular assist device support, 94 (67%) were successfully bridged to transplantation, and 1 (0.71%) showed native heart recovery. Twenty-four patients (17%) had been on continuous-flow left ventricular assist device support for more than 3 years (mean, 3.9 years; range, 3.0-7.5 years). Estimated on-device survival at 1, 3, and 5 years was 83%, 75%, and 61%, respectively. Rehospitalizations due to bleeding, cardiac events, and device-related issues were common. The freedom from rehospitalization rates at 1 and 3 years was 31% and 6.9%, respectively. A total of 14 patients (10%) required device exchange.

CONCLUSIONS

Current continuous-flow left ventricular assist devices can provide satisfactory long-term survival. However, rehospitalization is frequently required.

Hepatic and renal function with successful long-term support on a continuous flow left ventricular assist device

INTRODUCTION

Data regarding the long-term clinical effects of a continuous flow left ventricular assist device (CF-LVAD) on hepato-renal function is limited. Hence our aim was to assess changes in hepato-renal function over a one-year period in patients supported on a CF-LVAD.

METHODS

During the study period 126 patients underwent CF-LVAD implant. Changes in hepato-renal laboratory parameters were studied in 61/126 patients successfully supported on a CF-LVAD for period of one year. A separate cohort of a high-risk group (HCrB) of patients (56/126) with a serum creat>1.9 mg/dL (168 μmol/L) (75th percentile) or a serum bil>1.5 mg/dL (25.65 μmol/L) (75th percentile) was created. Changes in serum creatinine and bilirubin were analysed at regular intervals for this group along with the need for renal replacement therapy.

RESULTS

Baseline creatinine and blood urea nitrogen (BUN) for the entire cohort was 1.4[1.2,1.9 mg/dL] [123.7(106,168) μmol/L) and 27[20,39.5 mg/dL] [9.6(7.1,14.1) mmol/L] respectively. After an initial reduction at the end of one month [1(0.8,1.2) mg/dL; 88(70,105) μmol/L] (p<0.0001), a gradual increase was noted over the study period to reach (1.25[1.1,1.5] mg/dL; 106(97.2,132.6) μmol/L] (p=0.0003). The serum bilirubin normalised from a [1(0.7,1.55) mg/dL] [17(18.8,25.7) μmol/L) to 0.9(0.6,1.2)mg/dL [15.4(10.2,20.5) μmol/L] (p=0.0005) and continued to decline over one year. Improvement in the synthetic function of the liver was demonstrated by a rise in the serum albumin levels to reach 4.3[4.1,4.5] [43(41,45) gm/L] at the end of one year (p<0.0001). The baseline serum creatinine and bilirubin for the high-risk cohort (HCrB) was 1.9(1.3,2.4) mg/dL [168(115,212) μmol/L] and 1.7(1.00,2.4) mg/dL [29(17.1,68.4) μmol/L] respectively. The high-risk cohort (HCrB) demonstrated a trend towards higher 30-day mortality (p=0.06). While the need for temporary renal replacement therapy was higher in this cohort (16% vs. 4%; p=0.03), only 3% need it permanently. A significant reduction in creatinine was apparent at the end of one month [1.1(0.8,1.4) mg/dL; 97(70.7,123.7) μmol/L] (p<0.0001) and then remained stable at [1.3(1.1,1.5) mg/dL; 115(97,132.6) μmol/L]. Bilirubin demonstrated a 30% decline over one month and then remained low at [0.7(0.5,0.8) mg/dL; 62(44,70) μmol/L] p=0.0005 compared to the pre-operative baseline.

CONCLUSION

Hepato-renal function demonstrates early improvement and then remains stable in the majority of patients on continuous flow left ventricular assist device support for one year. High-risk patients demonstrate a higher 30-day mortality and temporary need for renal replacement therapy. Yet even in this cohort, improvement is present over a period of one year on the device, with a minimal need for permanent haemodialysis.