The role of bridge to transplantation: should LVAD patients be transplanted?

Association between the low percentage of forced vital capacity and increased mortality after left ventricular assist device implantation

Background

This study aims to investigate the effect of low percentage of forced vital capacity measured in the preoperative period on the 28-day mortality in patients undergoing left ventricular assist device implantation.

Methods

A total of 131 patients (111 males, 20 females; median age 54 years; range, 47 to 59 years) who underwent left ventricular assist device implantation with HeartWare™ between December 2010 and January 2016 were retrospectively analyzed. The patients were divided into two groups according to the results of pulmonary function test as a forced vital capacity percentage of ≥60% (n=113) and <60% (n=18). Both groups were compared in terms of laboratory and clinical characteristics, and postoperative complications. Risk factors for postoperative 28-day mortality were analyzed.

Results

Pre- and intraoperative characteristics were similar in both groups, except for left ventricular end-diastolic diameter. The ventilator-free days up to 28 days was shorter (p=0.046) and the length of intensive care unit stay was longer (p=0.011) in the low percentage of forced vital capacity group. The 28-day mortality rate was also higher (22.2% vs. 9.7%, respectively; p=0.12) in this group. The history of prior cardiac operation (odds ratio: 4.40; 95% confidence interval 1.19-16.20, p=0.026) and tricuspid valve repair at the time of device implantation (odds ratio: 5.30; 95% confidence interval 1.33-21.00, p=0.018) were found to be independent risk factors for mortality. Multivariate analysis showed that a forced vital capacity of <60% was not associated with mortality (odds ratio: 3.96; 95% confidence interval 0.95-16.43, p=0.058).

Conclusion

The length of intensive care unit stay and duration of mechanical ventilation may be longer in patients with a low percentage of forced vital capacity. Although the association between 28-day mortality and low percentage of forced vital capacity is not significant, the risk of 28-day mortality is higher in this group. Therefore, the patients should be assessed carefully before the left ventricular assist device operation.

Forensic Considerations in a Series of 14 Deaths of Patients with a Left Ventricular Assist Device

INTRODUCTION

To better understand the forensic implications of death with a left ventricular assist device (LVAD), we reviewed all deaths that were reported to a regional medical examiner jurisdiction involving patients who had an LVAD.

METHODS

Medical examiner case files between January 2012 and September 2018 were searched for "LVAD" and "left ventricular assist device" to identify deaths that were reported to the medical examiner involving a decedent who had an LVAD at the time of death.

RESULTS

During the study period, a total of 14 deaths were reported to the regional medical examiner involving decedents who had an implanted LVAD at the time of death. The average age at death was 64 years, with a range from 40 to 81 years. The underlying cardiac disease leading to LVAD implantation was ischemic heart disease (n = 9), nonischemic dilated cardiomyopathy (n = 4), and chemotherapy-related cardiotoxicity (n = 1). Of these 14 deaths, 2 deaths were due to loss of power to the LVAD, 1 death was due to traumatic subdural hemorrhage occurring in the setting of anticoagulation therapy required by LVAD implantation, and 1 death was due to femur fracture following a fall.

DISCUSSION

Medical examiners should be familiar with the potential complications of LVADs, especially those complications that may prompt consideration of non-natural manners of death. Medical examiners should also be aware of the tools and investigative strategies that may assist in the investigation of LVAD-related deaths.

Infections in patients after Berlin Heart® EXCOR assist device implantation

OBJECTIVES

Berlin Heart^® EXCOR devices (BHED) are ventricular assist devices (VAD) used mainly as a bridge to heart transplantation (HT) in pediatric population. The aim of our study is to report the infections diagnosed in adult patients undergoing a BHED implantation.

METHODS

Adult patients receiving a BHED between Jul 2009 and Oct 2017 at our institution were included. Infections were classified according to the International Society of Heart and Lung Transplantation definitions in VAD-Specific (VAD-S), VAD-Related (VAD-R) and non-VAD (N-VAD).

RESULTS

Fifteen patients underwent BHED implantation, which was maintained for a mean of 92 (19-195) days. Infection occurred in 13 patients who developed 36 infectious episodes: 5 VAD-S (5 cannula infections); 8 VAD-R (5 bloodstream infections and 3 mediastinitis) and 24 N-VAD (7 urinary tract infections, 6 Cytomegalovirus diseases and others). Overall, 27 (75%) were bacterial, 7 (19.4%) were viral and there was one (2.7%) fungal infection. Eleven patients underwent HT and all of them developed at least one infection after it. In 3 cases, all VAD-R or VAD-S infections were caused by the same etiology as before HT. Their median time of appearance was on day +6 (3-11) after BHED removal and HT. Overall mortality was 6/15 (40%). None of the deaths were related to VAD Infection.

CONCLUSIONS

Infection complicated BHED implantation in 86.7% of the patients. Overall, 13.9% were specific of BHED and 22.2% were related. However, infections did not preclude HT in any case and carried no attributable mortality.

Ovine Leukocyte Microparticles Generated by the CentriMag Ventricular Assist Device In Vitro

Ventricular assist devices (VADs) are a life-saving form of mechanical circulatory support in heart failure patients. However, VADs have not yet reached their full potential due to the associated side effects (thrombosis, bleeding, infection) related to the activation and damage of blood cells and proteins caused by mechanical stress and foreign materials. Studies of the effects of VADs on leukocytes are limited, yet leukocyte activation and damage including microparticle generation can influence both thrombosis and infection rates. Therefore, the aim was to develop a multicolor flow cytometry assessment of leukocyte microparticles (LMPs) using ovine blood and the CentriMag VAD as a model for shear stress. Ovine blood was pumped for 6 h in the CentriMag and regular samples analyzed for hemolysis, complete blood counts and LMP by flow cytometry during three different pump operating conditions (low flow, standard, high speed). The high speed condition caused significant increases in plasma-free hemoglobin; decreases in total leukocytes, granulocytes, monocytes, and platelets; increases in CD45⁺ LMPs as well as two novel LMP populations: CD11b^bright /HLA-DR^- and CD11b^dull /HLA-DR⁺ , both of which were CD14^- /CD21^- . CD11b^bright /HLA-DR^- LMPs appeared to respond to an increase in shear magnitude whereas the CD11b^dull /HLA-DR⁺ LMPs significantly increased in all pumping conditions. We propose that these two populations are released from granulocytes and T cells, respectively, but further research is needed to better characterize these two populations.

Oxidative stress induced modulation of platelet integrin α2bβ3 expression and shedding may predict the risk of major bleeding in heart failure patients supported by continuous flow left ventricular assist devices

INTRODUCTION

Oxidative stress and platelet integrin α2bβ3 plays important role in the process of hemostasis and thrombosis. We hypothesized that device-induced patient specific oxidative stress and integrin α2bβ3 shedding may be linked to major bleeding complication (MBC) in heart failure (HF) patients supported by continuous flow left ventricular assist devices (CF-LVADs).

MATERIALS AND METHODS

We recruited 47patients implanted with CF-LVADs and 15 healthy volunteers. Fourteen patients developed MBC (bleeder group) within one month after implantation while others were considered non-bleeder group (n=33). Oxidative stresses were evaluated by measuring reactive oxygen species (ROS) in platelets, superoxide dismutase (SOD) activity, total antioxidant capacity (TAC) and oxidized low density lipoprotein (oxLDL). Assessments of α2bβ3 were carried out using flow cytometry and ELISA.

RESULTS

Biomarkers of oxidative stress and α2bβ3 shedding (decreased surface expression and higher plasma levels) were found to be preexisting condition in all HF patients prior to CF-LVAD implantation compared to the healthy volunteers. Significantly elevated levels of ROS and oxLDL; concomitant depletion of SOD and TAC; and α2bβ3 shedding were observed in the bleeder group temporarily in comparison to the non-bleeder group after CF-LVAD implantation. A significantly strong association between α2bβ3 shedding and biomarkers of oxidative stress was observed; suggesting a potential role of oxidative stress in platelet integrin shedding leading to MBC after CF-LVAD implantation. Moreover, a receiver operating characteristic (ROC) analysis indicated that the likelihood of MBC data from Integrin α2bβ3 shedding had a predictive power of MBC in CF-LVAD patients.

CONCLUSIONS

Oxidative stress might play a potential role in accelerating α2bβ3 shedding and platelet dysfunction, resulting in MBC in CF-LVAD patients. Integrin α2bβ3 shedding may be used to refine bleeding risk stratification in CF-LVAD patients.

Improved Approach With Subcostal Exchange of the HeartMate II Left Ventricular Assist Device: Difference in On and Off Pump?

BACKGROUND

The HeartMate II (St. Jude Medical, Inc, St. Paul, MN [previously Thoratec]) left ventricular assist device (LVAD) exchange has traditionally involved a redo sternotomy. Alternate minimally invasive subcostal approaches have the advantage of avoiding sternal reentry, excessive bleeding, and prolonged recovery.

METHODS

This retrospective review included patients who underwent an exchange from May 2009 to March 2016. The patients were divided into three cohorts: (1) redo sternotomy, (2) subcostal approach involving cardiopulmonary bypass (CPB) (ON-CPB SC), and (3) subcostal approach off the CPB pump (OFF-CPB SC). Data pertaining to patients' baseline characteristics and outcomes were collected and analyzed.

RESULTS

From May 1, 2009 to July 31, 2016, 33 HeartMate II LVAD exchanges were performed. There were 11 redo sternotomies and 22 subcostal exchanges, 12 of which were in the OFF-CPB SC group. There was no significant difference among the groups in terms of age (p = 0.75), sex (p = 0.95), and indication for exchange (p = 0.94). There was a higher red blood cell transfusion requirement within the sternotomy cohort (p < 0.001). The median time to extubation and the intensive care unit length of stay were significantly shorter in the OFF-CPB SC group (1 and 2.5 days, respectively) than in the sternotomy (2.5 and 21 day, respectively) and ON-CPB SC groups (1.5 and 5 days, respectively). The 30-day and 90-day survival rates were equivalent among the cohorts.

CONCLUSIONS

Exchange of the HeartMate II LVAD can be accomplished with significantly improved recovery time and transfusion requirement through a less invasive subcostal approach when compared with sternotomy. The subcostal approach can be performed safely both on and off cardiopulmonary bypass.

Mechanistic insight of platelet apoptosis leading to non-surgical bleeding among heart failure patients supported by continuous-flow left ventricular assist devices

Non-surgical bleeding (NSB) is the most common clinical complication in heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). In this study, oxidative stress and alteration of signal pathways leading to platelet apoptosis were investigated. Thirty-one HF patients supported by CF-LVADs were divided into bleeder (n = 12) and non-bleeder (n = 19) groups. Multiple blood samples were collected at pre-implant (baseline) and weekly up to 1-month post-implant. A single blood sample was collected from healthy subjects (reference). Production of reactive oxygen species (ROS) in platelets, total antioxidant capacity (TAC), oxidized low-density lipoproteins (oxLDL), expression of Bcl-2 and Bcl-xL, Bax and release of cytochrome c (Cyt.c), platelet mitochondrial membrane potential (Δψ _m), activation of caspases, gelsolin cleavage and platelet apoptosis were examined. Significantly elevated ROS, oxLDL and depleted TAC were evident in the bleeder group compared to non-bleeder group (p < 0.05). Platelet pro-survival proteins (Bcl-2, Bcl-xL) were significantly reduced in the bleeder group in comparison to the non-bleeder group (p < 0.05). Translocation of Bax into platelet mitochondria membrane and subsequent release of Cyt.c were more prevalent in the bleeder group. Platelet mitochondrial damage, activation of caspases, gelsolin cleavage, and ultimate platelet apoptosis in the bleeder group were observed. Oxidative stress and activation of both intrinsic and extrinsic pathways of platelet apoptosis may be linked to NSB in CF-LVAD patients. Additionally, biomarkers of oxidative stress, examination of pro-survivals and pro-apoptotic proteins in platelets, mitochondrial damage, caspase activation, and platelet apoptosis may be used to help identify HF patients at high risk of NSB post-implant.

Ventricular Assist Device Implantation: Perioperative Nursing Considerations

Treatment for patients in end-stage heart failure has been revolutionized by the development of the ventricular assist device (VAD), an implantable heart pump used for long-term mechanical circulatory support. These devices are now small, lightweight, and efficient continuous-flow pumps that have replaced the larger, heavier, fill-to-empty predecessors. Management of the VAD case requires interdisciplinary effort across a diverse continuum of care and an understanding of new implantation techniques. This article describes current advances in VAD technology, indications for use, and perioperative nursing considerations related to patients who have undergone VAD implantation.

Comparison of early versus delayed timing of left ventricular assist device implantation as a bridge-to-transplantation: An analysis of the UNOS dataset

BACKGROUND

Placement of left ventricular assist devices (LVAD) as a bridge-to-heart transplantation (HTx) has rapidly expanded due to organ donor shortage. However, the timing of LVAD implantation is variable and it remains unclear if earlier implantation improves survival.

METHODS

We analyzed 14,187 adult candidates from the United Network of Organ Sharing database. Patients were classified by 3 treatment strategies including patients medically treated alone (MED, n=11,009), patients on LVAD support at listing (Early-LVAD, n=1588) and patients undergoing LVAD placement while awaiting HTx (Delayed-LVAD, n=1590). Likelihood of HTx and event-free survival were assessed in patients subcategorized by clinical strategies and UNOS status at listing.

RESULTS

The device support strategy, despite the timing of placement, was not associated with increased likelihood of HTx compared to MED group. However, both LVAD implantation strategies showed better survival compared to MED group (Early-LVAD: HR 0.811 and 0.633, 95% CI 0.668-0.984 and 0.507-0.789, for 1A and 1B; p=0.034 and p<0.001, Delayed-LVAD: HR 0.553 and 0.696, 95% CI 0.415-0.736 and 0.571-0.847, for 1A and 1B; both p<0.001, respectively). Furthermore, there was no significant difference in survival between these LVAD implantation strategies in patients listed as 1B (p=0.500), although Early-LVAD implantation showed worse survival in patients listed as 1A (HR 1.467, 95% CI 1.076-2.000; p=0.015).

CONCLUSION

LVAD support strategies offer a safe bridge-to-HTx. Those candidates who receive urgent upfront LVAD implantation for HTx, and improve to 1B status, would achieve competitive survival with those who receive elective LVAD implantation.

Use of PTFE patch for pericardial closure after minimal invasive LVAD implantation

The left ventricular assist device (LVAD) is now a routine therapy for advanced heart failure. The thoracotomy approach for LVAD implantation, in which the left ventricle is approached through a pericardial rent, is becoming popular. We demonstrate closure of the pericardial rent with a polytetrafluoroethylene (PTFE) patch and its advantages.

Oxy-RVAD: rescue in pulmonary complications after LVAD implantation

Pulmonary complications after left ventricular assist device (LVAD) implantation seldom occur; however, if present, they may prove catastrophic. An Oxy-RVAD (oxygenator in right VAD circuit) is a lifesaving technique in such cases and allows freedom of introducing and removing an oxygenator into the RVAD circuit without opening the chest and competing with LVAD flow.

Does CircuLite Synergy assist device as partial ventricular support have a place in modern management of advanced heart failure?

The discrepancy between the number of patients on the waiting list and available donor hearts has led to the successful development of left ventricular assist devices (LVAD) as a bridge to transplantation. The conventional LVADs are designed to provide full hemodynamic support for the end-stage failing heart. However, full-support LVAD implantation requires major surgery, sternotomy and cardiopulmonary bypass in majority of cases. The Synergy Micro-pump is the smallest implantable LVAD and provides partial flow support up to 3 l/min. It was shown that early intervention with this device can provide substantial benefits to patients with severe heart failure not yet sick enough for a full-support LVAD. Due the small dimensions it can be implanted without cardiopulmonary bypass or a sternotomy. The purpose of this article is to review the clinical use of the Synergy Micro-pump as partial hemodynamic support.

Outcomes and predictors of early mortality after continuous-flow left ventricular assist device implantation as a bridge to transplantation

Left ventricular assist devices (LVADs) are fast becoming standard of care for patients with advanced heart failure. However, despite continuous improvement in VAD technology, there remains a significant early postoperative morbidity and mortality in this extreme patient group. The aim of the current study was to explore the short-term outcomes and predictors for 90 day mortality in the patients after implantation of continuous-flow LVAD. Perioperative clinical, echocardiographic, hemodynamic, and laboratory data of 90 day survivors and nonsurvivors were collected and compared retrospectively. Multivariate logistic regression analysis was performed on univariate predictors for 90 day mortality with an entry criterion of p < 0.1. Between July 2006 and May 2012, 117 patients underwent implantation of a continuous-flow LVAD as a bridge to transplantation: 71 (60.7%) HeartMate II (Thoratec Corp, Pleasanton, CA) and 46 (39.3%) HVAD (HeartWare International, Framingham, MA). All-cause 90 day mortality was 17.1%. Multivariate analysis revealed higher preoperative central venous pressure (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.014-1.378; p = 0.033) and higher age (OR, 1.14; 95% CI, 1.01-1.38; p = 0.045) as the only independent predictors for 90 day mortality. Optimization of preoperative volume status, preload, and right heart function as well as age-based selection of candidates for LVAD support are the critical factors influencing early outcome after continuous-flow LVAD implantation.

Intraplatelet reactive oxygen species, mitochondrial damage and platelet apoptosis augment non-surgical bleeding in heart failure patients supported by continuous-flow left ventricular assist device

Non-surgical bleeding (NSB) is the most common clinical complication among heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). Understanding the role of platelet functionality contributing to NSB after CF-LVAD implantation is crucial for prevention and management of this adverse event. The aim of this study was to examine the role of intraplatelet reactive oxygen species (ROS) and platelet damage on the incidence of bleeding events after CF-LVAD implantation in HF patients. We recruited 25 HF patients implanted with CF-LVADs and 11 healthy volunteers as the control. Intraplatelet ROS generation, platelet mitochondrial damage and platelet apoptosis were quantified by flow cytometry. Among 25 patients, 8 patients developed non-surgical bleeding within one month after CF-LVAD implantation. Intraplatelet ROS, depolarized and apoptotic platelet were found to be pre-existing conditions in all baseline samples of the 25 HF patients when compared to the healthy volunteers. There was no significant difference in the levels of ROS between the non-bleeder and the bleeder groups prior to CF-LVAD implantation, although we noticed 2-fold and 1.5-fold rise in depolarized and apoptotic platelets, respectively, in the bleeder group compared to those in the non-bleeder group. Post implant levels of intraplatelet ROS, depolarized and apoptotic platelets increased and remained elevated in the bleeder group, whereas periodic decreases were noticed in the non-bleeder group, suggesting the potential role of platelet damage on bleeding incidence. ROS generation after CF-LVAD implantation positively associated with platelet apoptosis (ρ = 0.4263, p = 0.0023) and depolarized platelets (ρ = 0.4774, p = 0.0002), especially the latter. In conclusion, elevated intraplatelet ROS and platelet damage may be linked to the NSB among HF patients supported by CF-LVAD. These results provide mechanistic insights into the bleeding complication in patients with CF-LVAD support.

Use of Foley catheter for insertion of ventricular assist device inflow cannula

Ventricular assist devices are fast becoming an accepted alternative to treat end-stage heart failure, and are being implemented as a bridge to myocardial recovery, a bridge to heart transplantation, or as destination therapy. Positioning of the inflow cannula into the apex of the ventricle is a crucial step due to the risk of sucking in air. We describe an improved method of preparing the insertion site for the ventricular assist device inflow cannula, to minimize the chances of air embolism and blood spillage, which we applied in a 34-year-old man, as a bridge to transplantation.

Staged and effortless explantation of CircuLite Synergy micropump

Synergy(®) micropump was implanted as a bridge to heart transplantation in a middle-age lady with chronic advanced heart failure due to dilated cardiomyopathy. After a good initial recovery, patient was discharged to ward, where her stay was prolonged due to non-healing operative wound over the micropump and recurrent gastrointestinal bleeding. After 3 months of therapy, the heart seemed to be recovered and the micropump was explanted. In view of the patient's bleeding tendency, the micropump was explanted in staged manner.

Platelet glycoprotein Ibα ectodomain shedding and non-surgical bleeding in heart failure patients supported by continuous-flow left ventricular assist devices

BACKGROUND

Non-surgical bleeding (NSB) is a major complication among heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). Understanding the hemostatic defects contributing to NSB after CF-LVAD implantation is crucial for prevention of this adverse event. The aim of this study was to examine the link between platelet glycoprotein Ibα (GPIbα) ectodomain shedding and NSB in CF-LVAD recipients and to identify a potential biomarker of NSB.

METHODS

Serial blood samples were collected from 35 HF patients supported with CF-LVADs. Platelet function was evaluated by a platelet function analysis device and thromboelastography (TEG). Platelet GPIbα shedding, von Willebrand factor (vWF) antigen and vWF collagen binding capacity were determined using enzyme-linked immunosorbent assays (ELISAs). The structural analysis of vWF was performed by gel electrophoresis. These platelet function measures with vWF parameters of the patients who had NSB between 4 and 32 days after CF-LVAD implantation (bleeder) were analyzed against those without NSB (non-bleeder). Blood samples from 7 healthy individuals were collected to obtain healthy reference values for the laboratory assays.

RESULTS

Elevated GPIbα shedding was found to be a pre-existing condition in all HF patients prior to CF-LVAD implantation. Post-operative level of GPIbα shedding increased and remained elevated in the bleeder group, whereas a consistent decrease was found in the non-bleeder group. A receiver operating characteristic (ROC) analysis indicated that the level of GPIbα shedding had a predictive power of NSB in patients on CF-LVAD support.

CONCLUSIONS

Platelet GPIbα ectodomain shedding which attenuates platelet reactivity is associated with NSB. Plasma GPIbα level may potentially be used to refine bleeding risk stratification in CF-LVAD patients.

Pre-operative echocardiographic features associated with persistent mitral regurgitation after left ventricular assist device implantation

BACKGROUND

Previous studies have shown remarkable decrease in size of the left ventricle after left ventricular assist device (LVAD) implantation due to mechanical unloading. However, a certain number of patients continue to have significant mitral regurgitation (MR) under LVAD support. We investigated pre-operative echocardiographic features associated with persistent MR after LVAD implantation.

METHODS

We retrospectively reviewed 82 consecutive patients undergoing continuous-flow LVAD implantation between 2007 and 2010. We obtained echocardiograms performed within 2 weeks before and 1 week after surgery. We investigated the pre-operative echocardiographic findings associated with significant MR post-LVAD and compared 1-year mortality after LVAD surgery between patients with and without significant MR post-LVAD.

RESULTS

MR was significant in 43 patients (52.4%) before LVAD surgery. Among those, 5 underwent concomitant mitral valve repair (MVr) at the time of LVAD implantation. Of the remaining 38 patients, 25 (65.8%) showed improvement of MR, whereas 13 patients (34.2%) continued to have significant MR post-LVAD. Multivariate analysis revealed that posterior displacement of the coaptation point of mitral leaflets was significantly associated with significant MR post-LVAD (hazard ratio, 1.335; 95% confidence interval, 1.035-1.721; p = 0.026) even after adjusting for the amount of pre-operative MR flow. Post-LVAD 1-year survival of patients with and without significant MR post-LVAD was not significantly different (92.3% vs 89.1%, p = 0.826).

CONCLUSIONS

Pre-LVAD posterior displacement of mitral leaflets may be indicative of post-operative significant MR, which would help identify echocardiographic features of functional MR refractory to simple volume reduction of the ventricle.

Renal replacement therapy in congestive heart failure requiring left ventricular assist device augmentation

"Cardiorenal syndrome" is a term used to describe a dys-regulation of the heart affecting the kidneys, or vice versa, in an acute or chronic manner (1,2). Renal impairment can range from reversible ischemic damage to renal failure requiring short- or long-term renal replacement therapy (2). Patients who require mechanical circulatory support, such as a left ventricular assist device (LVAD), as definitive treatment for congestive heart failure or as a bridge to cardiac transplantation pose a unique challenge with respect to receiving dialysis, because they experience higher rates of morbidity and mortality from infection in the post-LVAD period (3-7). Acute dialysis access can pose an increased infection risk. In this article, we present a patient who required renal replacement therapy and a LVAD for management of acute-on-chronic cardiorenal syndrome while awaiting heart transplantation. A literature review to determine whether peritoneal dialysis or hemodialysis is superior for patients with profound hemodynamic dysfunction and the need to minimize risk of infection did not offer clear guidance about which modality is superior in patients with advanced congestive heart failure. However, there is clear evidence of the superiority of peritoneal dialysis in reducing the risk of systemic infection secondary to acute dialysis access. Given the high risk of LVAD infection, we therefore conclude that, to decrease mortality secondary to systemic infection, peritoneal dialysis should strongly be considered in patients who require renal replacement therapy before or after LVAD placement.

Mitral commissurotomy through the left ventricle apical orifice with Heart Ware left ventricular assist device implantation

Diseased, replaced or repaired mitral valve can lead to restricted blood flow to left ventricle and inadequate flow in left ventricular assist device (LVAD). A middle age woman with ‘burnt out’ hypertrophic cardiomyopathy had mitral valve repair for mitral regurgitation. She needed LVAD to support severe decompensating heart failure. Repaired mitral valve posed a risk of restricted flow through the device. Mitral commissurotomy was performed on beating heart through the left ventricular apical hole created for insertion of inflow cannula of LVAD.

Oxidative stress, DNA damage and repair in heart failure patients after implantation of continuous flow left ventricular assist devices

OBJECTIVE

To study the status of oxidative stress and DNA damage repair in circulating blood leukocytes of heart failure patients supported by continuous flow left ventricular assist devices (LVADs).

MATERIALS AND METHODS

Ten HF patients implanted with LVAD as bridge to transplant or destination therapy were enrolled in the study and 10 age and sex matched volunteers were recruited as the study control. Reactive oxygen species (ROS) in blood leukocytes and superoxide dismutase (SOD) in erythrocytes were measured by flow cytometry/immunofluorescence microscopy and spectrophotometry, respectively. ELISA was used to measure oxidized low density lipoproteins (oxLDL) in plasma. Markers of DNA damage (γ-H2AX) and repairs (Mre11, DNA ligase IV, Ku70, and Ku80) were quantified in blood lymphocytes by immunocytochemistry.

RESULTS

Levels of ROS and oxLDL were significantly higher in HF patients with LVAD than baseline as well as the control group; moreover, SOD levels were decreased with increasing post-operative periods. All the changes indicated enhanced oxidative stress among LVAD recipients. Significantly higher γ-H2AX foci in lymphocytes confirmed DNA double strand breaks in LVAD recipients. γ-H2AX foci numbers in lymphocytes were positively correlated with the ROS and oxLDL and negatively with SOD levels (p<0.0001). Expressions of DNA ligase IV, Ku70 and Ku80 proteins were highest after one week and Mre11 protein after 3 months of LVAD transplantation; indicated abnormal DNA repair.

CONCLUSIONS

The study, for the first time shows that, continuous flow LVAD implanted HF patients not only exhibit elevated oxidative stress and DNA damage in blood leukocytes but also have abnormalities in DNA repair pathways.

The future of adult cardiac assist devices: novel systems and mechanical circulatory support strategies

The recent, widespread success of mechanical circulatory support has prompted the development of numerous implantable devices to treat advanced heart failure. It is important to raise awareness of novel device systems, the mechanisms by which they function, and implications for patient management. This article discusses devices that are being developed or are in clinical trials. Devices are categorized as standard full support, less-invasive full support, partial support: rotary pumps, partial support: counterpulsation devices, right ventricular assist device, and total artificial heart. Implantation strategy, mechanism of action, durability, efficacy, hemocompatibility, and human factors are considered. The feasibility of novel strategies for unloading the failing heart is examined.

Pre-operative and post-operative risk factors associated with neurologic complications in patients with advanced heart failure supported by a left ventricular assist device

BACKGROUND

Neurologic complications (NCs) are the major adverse events after left ventricular assist device (LVAD) surgery. Pre-operative and post-operative factors associated with NCs in patients with LVADs were investigated.

METHODS

We reviewed 307 consecutive patients undergoing LVAD surgery (167 HeartMate I and 140 HeartMate II devices) at Columbia University Medical Center between November 2000 and December 2010. Clinical characteristics and hemodynamic and laboratory indexes were analyzed. NC was defined according to the Interagency Registry for Mechanically Assisted Circulatory Support definition of neurologic dysfunction, including transient ischemic attack (TIA) and ischemic or hemorrhagic cerebrovascular accident (CVA).

RESULTS

NCs developed in 43 patients (14.0%) at 91.8 ± 116.3 days post-operatively. The frequency of NC development was similar in HeartMate I and II patients. Patients with NC showed a higher frequency of pre-LVAD CVA history (27.9% vs 15.5%, p = 0.046), lower pre-operative sodium (129.0 ± 7.0 vs 132.1 ± 8.1 mg/dl, p = 0.018) and albumin concentrations (3.5 ± 0.7 vs 3.7 ± 0.6 mg/dl, p = 0.049), lower post-operative hematocrit (34.9% ± 5.1% vs 37.8% ± 6.1%, p = 0.0034), sodium (131.6 ± 7.7 vs 134.4 ± 6.4 mg/dl, p = 0.010) and albumin concentrations (3.7 ± 0.5 vs 3.9 ± 0.5 mg/dl, p = 0.0016), and higher frequency of post-operative infection (39.5% vs 19.3%, p = 0.003) than those without NC. Multiple regression analysis revealed that CVA history (odds ratio, 2.37, 95% confidence interval, 1.24-5.29; p = 0.011) and post-operative infection (odds ratio, 2.99, 95% confidence interval, 1.16-10.49; p = 0.011) were highly associated with NC development. The combination of CVA history, pre-operative and post-operative sodium and albumin, and post-operative hematocrit and infection could discriminate patients developing NCs with a probability of 76.6%.

CONCLUSIONS

Previous stroke, persistent malnutrition and inflammation, severity of heart failure, and post-LVAD infections are key factors associated with development of NCs after LVAD implantation.

Effects of continuous-flow versus pulsatile-flow left ventricular assist devices on myocardial unloading and remodeling

BACKGROUND

Continuous-flow left ventricular assist devices (LVAD) are increasingly used for patients with end-stage heart failure (HF). We analyzed the effects of ventricular decompression by continuous-flow versus pulsatile-flow LVADs on myocardial structure and function in this population.

METHODS AND RESULTS

Sixty-one patients who underwent LVAD implantation as bridge-to-transplant were analyzed (pulsatile-flow LVAD: group P, n=31; continuous-flow LVAD: group C, n=30). Serial echocardiograms, serum levels of brain natriuretic peptide (BNP), and extracellular matrix biomarkers (ECM) were compared between the groups. Myocardial BNP and ECM gene expression were evaluated in a subset of 18 patients. Postoperative LV ejection fraction was greater (33.2±12.6% versus 17.6±8.8%, P<0.0001) and the mitral E/E' was lower (9.9±2.6 versus 13.2±3.8, P=0.0002) in group P versus group C. Postoperative serum levels of BNP, metalloproteinases (MMP)-9, and tissue inhibitor of MMP (TIMP)-4 were significantly lower in group P compared with group C (BNP: 552.6±340.6 versus 965.4±805.7 pg/mL, P<0.01; MMP9: 309.0±220.2 versus 475.2±336.9 ng/dL, P<0.05; TIMP4: 1490.9±622.4 versus 2014.3±452.4 ng/dL, P<0.001). Myocardial gene expression of ECM markers and BNP decreased in both groups; however, expression of TIMP-4 decreased only in group P (P=0.024).

CONCLUSIONS

Mechanical unloading of the failing myocardium using pulsatile devices is more effective as indicated by echocardiographic parameters of systolic and diastolic LV function as well as dynamics of BNP and ECM markers. Therefore, specific effects of pulsatile mechanical unloading on the failing myocardium may have important implications for device selection especially for the purpose of bridge-to-recovery in patients with advanced HF.

Morphological and molecular changes of the myocardium after left ventricular mechanical support

Left ventricular assist devices (LVAD) are currently used to either “bridge” patients with terminal congestive heart failure (CHF) until cardiac transplantation is possible or optionally for patients with contraindications for transplantation (“destination therapy”). Mechanical support is associated with a marked decrease of cardiac dilation and hypertrophy as well as numerous cellular and molecular changes (“reverse cardiac remodeling”), which can be accompanied by improved cardiac function (“bridge to recovery”) in a relatively small subset of patients with heart transplantation no longer necessary even after removal of the device (“weaning”). In the recent past, novel pharmacological strategies have been developed and are combined with mechanical support, which has increased the percentage of patients with improved clinical status and cardiac performance. Gene expression profiles have demonstrated that individuals who recover after LVAD show different gene expression compared to individuals who do not respond to unloading. This methodology holds promise for the future to develop read out frames to identify individuals who can recover after support. Aside from describing the morphological changes associated with “reverse cardiac remodeling”, this review will focus on signal transduction, transcriptional regulation, apoptosis, cell stress proteins, matrix remodeling, inflammatory mediators and aspects of neurohormonal activation in the failing human heart before and after ventricular unloading.

Flow dynamics of a novel counterpulsation device characterized by CFD and PIV modeling

BACKGROUND

Historically, single port valveless pneumatic blood pumps have had a high incidence of thrombus formation due to areas of blood stagnation and hemolysis due to areas of high shear stress.

METHODS

To ensure minimal hemolysis and favorable blood washing characteristics, particle image velocimetry (PIV) and computational fluid dynamics (CFD) were used to evaluate the design of a new single port, valveless counterpulsation device (Symphony). The Symphony design was tested in 6-h acute (n=8), 5-day (n=8) and 30-day (n=2) chronic experiments in a calf model (Jersey, 76 kg). Venous blood samples were collected during acute (hourly) and chronic (weekly) time courses to analyze for temporal changes in biochemical markers and quantify plasma free hemoglobin. At the end of the study, animals were euthanized and the Symphony and end-organs (brain, liver, kidney, lungs, heart, and spleen) were examined for thrombus formations.

RESULTS

Both the PIV and the CFD showed the development of a strong moving vortex during filling phase and that blood exited the Symphony uniformly from all areas during ejection phase. The laminar shear stresses estimated by CFD remained well below the hemolysis threshold of 400 Pa inside the Symphony throughout filling and ejection phases. No areas of persistent blood stagnation or flow separation were observed. The maximum plasma free hemoglobin (<10mg/dl), average platelet count (pre-implant = 473 ± 56 K/μl and post-implant = 331 ± 62 K/μl), and average hematocrit (pre-implant = 31 ± 2% and post-implant = 29 ± 2%) were normal at all measured time-points for each test animal in acute and chronic experiments. There were no changes in measures of hepatic function (ALP, ALT) or renal function (creatinine) from pre-Symphony implantation values. The necropsy examination showed no signs of thrombus formation in the Symphony or end organs.

CONCLUSIONS

These data suggest that the designed Symphony has good washing characteristics without persistent areas of blood stagnation sites during the entire pump cycle, and has a low risk of hemolysis and thrombus formations.

Thyroid hormone and chronically unloaded hearts

The heart is subjected to chronic mechanical unloading during prolonged spaceflight and microgravity. The heart in patients with end-stage heart failure is also unloaded in prolonged duration after left ventricular assist devices (LVAD) are implanted. Heterotopic heart transplantation in rats is an established model of chronic cardiac unloading, and has been used to investigate the effects of chronic cardiac unloading on the heart. Observations that have been found using this experimental model are as follow. Chronic cardiac unloading induces time-dependent depressions of Ca2+ handling and myocyte contractility, which are associated with the shift of myosin heavy chain (MHC) isozymes and altered expressions of Ca2+ cycling-related proteins. Treatment with the physiological treatment dose of thyroid hormone restores the expression levels of Ca2+ cycling-related proteins, Ca2+ handling, and contractile function of cardiac myocytes in chronically unloaded hearts. Although future studies are required to determine precise mechanisms of the beneficial effects of thyroid hormone on chronically unloaded hearts, these observations may have clinical implications in the future for chronic cardiac unloading in the space industry as well as in the treatment of patients with end-stage heart failure supported by LVAD.

The use of continuous milrinone therapy as bridge to transplant is safe in patients with short waiting times

OBJECTIVE

The limited availability of donor organs creates a need for more effective management of heart disease when bridging a patient to cardiac transplant. Inotropic therapy is becoming more commonly used long term to maintain baseline function. The effectiveness and complications associated with their use have not been fully evaluated, and indications for mechanical versus medical therapy as a bridge have not been delineated.

METHODS AND RESULTS

The purpose of this study is to evaluate the safety and efficacy of milrinone as a bridge to transplant. This was a retrospective study of 60 patients listed for a cardiac transplant and committed to home intravenous milrinone therapy. A subgroup of patients who eventually progressed to the use of a ventricular assist device were analyzed. Complications and survivals were analyzed for each group. Forty-six patients (76%) were successfully bridged to transplant with milrinone alone, and 14 patients' (24%) conditions deteriorated and required a left ventricular assist device (LVAD); 1-year survivals were 83% and 71%, respectively. The mean waiting time was 59.5 days (9-257 days) for patients receiving milrinone who did not require an LVAD and 112 days (24-270 days) for those whose conditions deteriorated to require an LVAD.

CONCLUSIONS

This study suggests that chronic intravenous milrinone provides an adequate strategy as a bridge to transplant if the waiting time is short (<100 days), whereas an elective ventricular assist device implantation may be a safer strategy for patients expected to wait longer. These data provide the basis for a prospective evaluation of inotrope versus LVAD as a bridge to transplantation.

Location and density of alpha- and beta-adrenoreceptor sub-types in myocardium after mechanical left ventricular unloading

BACKGROUND

We hypothesized that not all subtypes of alpha- and beta-adrenoreceptors undergo similar upregulation and redistribution in human myocardium after mechanical unloading with an assist device.

METHODS

We obtained core biopsy samples of the left ventricle in 19 patients before and after removal of a Jarvik or Thoratec left ventricular assist device (LVAD) to study the effect of mechanical unloading on the distribution of alpha- and beta-adrenoreceptors. Fresh, embedded tissue sections were incubated with receptor blockers and antibodies before the fluorescent labeling of receptors. Images were obtained by fluorescence deconvolution microscopy, and composite tissue renditions were made from the stacked images. Multiple adrenoreceptor subtypes were studied.

RESULTS

We saw a reversal of myocyte hypertrophy in all patients, but the upregulation of receptors was not seen in all post-LVAD tissue samples. Furthermore, we noted receptor relocalization from an initial punctate/clumped pattern to a normal homogeneous distribution in many patients. Significant differences were seen in the distribution of beta(2)- and alpha(1)-receptors and in alpha(1A) subtypes.

CONCLUSIONS

In this study we show not only the expected reversal of myocyte hypertrophy and the increase in adrenoreceptors after ventricular unloading, but also the relocalization of specific receptor subtypes.

Current State of the Art in Myocardial Tissue Engineering

Myocardial tissue engineering aims to repair, replace, and regenerate damaged cardiac tissue using tissue constructs created ex vivo. This approach may one day provide a full treatment for several cardiac disorders, including congenital diseases or ventricular dysfunction after myocardial infarction. Although the ex vivo construction of a myocardium-like tissue is faced with many challenges, it is nevertheless a pressing objective for cardiac reparative medicine. Multidisciplinary efforts have already led to the development of promising viable muscle constructs. In this article, we review the various concepts of cardiac tissue engineering and their specific challenges. We also review the different types of existing biografts and their physiological relevance. Although many investigators have favored cardiomyocytes, we discuss the potential of other clinically relevant cells, as well as the various hypotheses proposed to explain the functional benefit of cell transplantation.

Ventricular assist devices in children: current achievements and future perspectives

Mechanical circulatory support systems for the treatment of acute and chronic heart failure are now available for use in several clinical situations and are designed for different indications and support times. In children, particularly in small infants, extracorporeal membrane oxygenation and centrifugal pumps have been most widely used in the past. These systems are preferred for support after cardiac operations and for use in patients who have concomitant respiratory failure, but they are suitable for short-term application only and intensive care is obligatory. VADs are designed for long-term application and allow patients to be discharged home. Pneumatic pulsatile VADs have been available in pediatric sizes since 1992. Currently at our institution, 74 children have been supported with pediatric extracorporeal VADs for up to 14 months. In the past five yr, a notable rise in survival has been achieved by improvements in pump design and pre- and post-operative management. We have been able to discharge 78% of the infants under one yr old. In this review, our current VAD experience in children will be presented in the light of improvements in decision-making, device technology, and implantation techniques, and in coagulation monitoring and anticoagulation. Additionally, new developments in the field of pediatric assist devices will be presented.

Left Ventricular Circulatory Support as Bridge to Heart Transplantation in Chagas' Disease Cardiomyopathy

This study was performed to assess the safety and feasibility of the implantation of ventricular assist devices (VADs) as a bridge to heart transplantation in patients with advanced biventricular failure due to Chagas' disease. Six patients were submitted to paracorporeal left VAD implantation, while right ventricular dysfunction was managed clinically. The mean time of circulatory support was 27 days. Two patients were bridged to heart transplantation successfully, while the other four patients died under assistance with complications that correlated with the final situation of multiple organ failure. Nevertheless, persistent right ventricular dysfunction was observed only in one patient who survived more than 15 days, despite the general significant preoperative compromise of the right ventricle. This paradoxical observation indicates that left VAD implantation may be regarded as a valuable treatment option for patients with Chagas' disease cardiomyopathy who evolve with decompensated heart failure or cardiogenic shock.

Levitronix Ventricular Assist Devices as a Bridge to Recovery After Profound Biventricular Heart Failure Associated With Pulmonary Aspergillosis

A patient with multisystem organ failure and refractory cardiopulmonary shock stemming from Aspergillus pneumonia was treated with 2 Levitronix ventricular assist devices as a bridge-to-recovery. After ventricular assist device placement, the patient recovered myocardial function. The ventricular assist devices were removed on post-implant Day 7, and the patient made a full long-term recovery. Ventricular assist devices should be strongly considered, as bridges to recovery, to support patients with acute myocardial dysfunction associated with sepsis while the underlying infection is treated.

Palliative care and hospice in advanced heart failure

This paper provides an evidence-based review of the principles underlying palliative care for heart failure (HF), including its pathogenesis, staging, assessment, prognosis, and treatment. Approaches to advanced care planning, symptom management, hospice eligibility, home inotropic infusions, device management and improving the continuum of care in HF are discussed. The reader will be able to recognize advanced HF, use important elements of physical assessment, utilize Web-based prognostic and risk-stratification models, facilitate advance care planning, ensure optimal treatment, manage common symptoms and comorbid conditions, determine hospice eligibility, and consider issues related to withholding or withdrawal of inotropic infusions and devices used in HF refractory to standard treatment. The ultimate goal of palliative care for heart failure is to integrate knowledge of treatment advances and comfort measures and to provide them concurrently in a seamless continuum to patients with late-stage disease.

Depressed contractile reserve and impaired calcium handling of cardiac myocytes from chronically unloaded hearts are ameliorated with the administration of physiological treatment dose of T3 in rats

AIM

Chronic cardiac unloading causes a time-dependent upregulation of phospholamban (PLB) and depression of myocyte contractility in normal rat hearts. As thyroid hormone is known to decrease PLB expression, we examined whether thyroid hormone restores the depressed contractile performance of myocytes from chronically unloaded hearts.

METHODS

Cardiac unloading was induced by heterotopic heart transplantation in isogenic rats for 5 weeks. Animals were treated with either vehicle or physiological treatment dose of 3,5,3'-triiodo-L-thyronine (T3) that does not cause hyperthyroidism for the last 3 weeks (n=20 each).

RESULTS

In vehicle-treated animals, myocyte relaxation and [Ca2+]i decay were slower in unloaded hearts than in recipient hearts. Myocyte shortening in response to high [Ca2+]o was also depressed with impaired augmentation of peak-systolic [Ca2+]i in unloaded hearts compared with recipient hearts. In vehicle-treated rats, protein levels of PLB were increased by 136% and the phosphorylation level of PLB at Ser16 were decreased by 32% in unloaded hearts compared with recipient hearts. By contrast, in the T3-treated animals, the slower relaxation, delayed [Ca2+]i decay, and depressed contractile reserve in myocytes from unloaded hearts were all returned to normal levels. Furthermore, in the T3-treated animals, there was no difference either in the PLB protein level or in its Ser16-phosphorylation level between unloaded and recipient hearts.

CONCLUSION

These results suggest that the treatment with physiological treatment dose of thyroid hormone rescues the impaired myocyte relaxation and depressed contractile reserve at least partially through the restoration of PLB protein levels and its phosphorylation state in chronically unloaded hearts.