INTERMACS: interval analysis of registry data

Computational Fluid Dynamics Model of Continuous-Flow Total Artificial Heart: Right Pump Impeller Design Changes to Improve Biocompatibility

Cleveland Clinic is developing a continuous-flow total artificial heart (CFTAH). This novel design operates without valves and is suspended both axially and radially through the balancing of the magnetic and hydrodynamic forces. A series of long-term animal studies with no anticoagulation demonstrated good biocompatibility, without any thromboemboli or infarctions in the organs. However, we observed varying degrees of thrombus attached to the right impeller blades following device explant. No thrombus was found attached to the left impeller blades. The goals for this study were: (1) to use computational fluid dynamics (CFD) to gain insight into the differences in the flow fields surrounding both impellers, and (2) to leverage that knowledge in identifying an improved next-generation right impeller design that could reduce the potential for thrombus formation. Transient CFD simulations of the CFTAH at a blood flow rate and impeller rotational speed mimicking in vivo conditions revealed significant blade tip-induced flow separation and clustered regions of low wall shear stress near the right impeller that were not present for the left impeller. Numerous right impeller design variations were modeled, including changes to the impeller cone angle, number of blades, blade pattern, blade shape, and inlet housing design. The preferred, next-generation right impeller design incorporated a steeper cone angle, a primary/splitter blade design similar to the left impeller, and an increased blade curvature to better align the incoming flow with the impeller blade tips. The next-generation impeller design reduced both the extent of low shear regions near the right impeller surface and flow separation from the blade leading edges, while maintaining the desired hydraulic performance of the original CFTAH design.

Long-term follow-up of patients supported with the HeartWare left ventricular assist system

The aim of the present study is to report our long-term experience with the HeartWare Ventricular Assist System (HVAD). Between July 2009 and February 2018, a total of 103 patients (mean age 50.0 ± 14.4, range 28-74 years; 22 females) received HVAD implantation in a single center institution. A total of 26 (25.4%) patients were in cardiogenic shock preoperatively and received extracorporeal life support (ECLS) prior to HVAD implantation. The aim of left ventricular assist device (LVAD) implantation was bridge to transplantation (BT) in 59 (57.3%), destination therapy (DT) in 28 (27.2%), and bridge to decision in 16 (15.5%). There were 211.1 total patient years of support. Mean survival was 2.05 ± 2.14 years. Kaplan-Meier analysis showed an overall survival rate of 69.7%, 56.7%, 46.0%, and 25.0% at 1, 2, 4, and 8 years, respectively. A total of 23 patients (22.3%) died during the hospital stay. Of them 65.2% (15 patients) were preoperatively in cardiogenic shock (INTERMACS 1). Sub-analysis of the BT patients showed a mean survival of 2.45 ± 2.29 years with a survival rate of 85.1%, 75.1%, 67.2%, and 44.8% at 1, 2, 4, and 8 years, respectively. Among them, 20 patients received heart transplantation on follow-up. Mean survival of DT patients was 2.18 ± 1.91 years with a survival rate of 67.9%, 49.0%, and 25.1% at 1, 2, and 4 years, respectively. At latest follow-up in September 2018, 26 patients (25.24%) were still on LVAD. A total of five patients completed 6 years on LVAD, of them two were supported over 8 years. The most common adverse event reported was gastrointestinal bleeding requiring rehospitalization (0.161 EPPY). A total of 19 patients reported disabling stroke. Pump thrombosis was diagnosed in six patients (5.8%) (0.02 EPPY), of them four patients underwent pump exchange. To the best of our knowledge, this is the longest experience with HVAD reported so far. Patients supported with an HVAD show a satisfactory long-term survival. Further multicenter evaluations are needed to confirm these single-center results.

Long-Term Survival of Patients With Advanced Heart Failure Receiving an Left Ventricular Assist Device Intended as a Bridge to Transplantation: The Registry to Evaluate the HeartWare Left Ventricular Assist System

BACKGROUND

The paucity of available hearts for transplantation means that more patients remain on durable left ventricular support for longer periods of time. The Registry to Evaluate the HeartWare Left Ventricular Assist System was an investigator-initiated multicenter, prospective, single-arm database established to collect post-Conformité Européene mark clinical information on patients receiving the HeartWare ventricular assist device system as a bridge to transplantation. This registry represents the longest multicenter follow-up of primary left ventricular assist device outcomes.

METHODS

Data were collected on 254 commercial implants performed between February 2009 and March 2012 from 9 centers in Europe (7) and Australia (2). Patients were followed to device explant, heart transplantation, or death. The outcomes of patients through July/August 2018 were analyzed. Summary statistics were used to describe patient demographics, adverse events, length of support, and outcomes for this extended-term cohort.

RESULTS

A total of 122 patients were on support for >2 years, and 34 patients were on support for >5 years. Twenty nine patients are still alive on support (support ranging from 1213 to 3396 days), and 23 of those are on their original HeartWare ventricular assist device system. Kaplan-Meier survival through 7 years was 51%. Through 6 years, freedom from any stroke was 82%, while freedom from severely disabling stroke was 89%.

CONCLUSIONS

Low rates of heart transplant now require longer periods of left ventricular assist device support in patients. This analysis demonstrates that long-term support using a HeartWare ventricular assist device system offers survival of 51% through 7 years.

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.

Contemporary Treatment of Heart Failure

Heart failure (HF) affects 2.4% of the adult population in the United States and is associated with high health care costs. Medical and device therapy delay disease progression and improve survival in HF with reduced ejection fraction. Stage D HF is characterized by significant functional limitation, frequent HF hospitalization for decompensation, intolerance of medical therapy, use of inotropes, and high diuretic requirement. Advanced therapies with left ventricular assist devices and cardiac transplantation reduce mortality and improve quality of life, and early referral to specialized centers is imperative for patient selection and success with these therapies.

Controller and battery changes due to technical problems related to the HVAD® left ventricular assist device - a single center experience

Background

The use of left ventricular assist devices (LVADs) has increased in the last decade. Major complications have been well described, but there is no data on device alarms and actual or threatening malfunction which impair quality of life and may impair outcomes. This study describes the technical problems related to the use of the HVAD® left ventricular assist device in a single center.

Methods

We retrospectively reviewed device malfunctions and outcomes in 22 patients with HVAD® left ventricular assist device followed at Karolinska University Hospital between 2011 and 2016. Device malfunction was defined by INTERMACS as a failure of one or more of the components of the LVAD system. The primary outcome was defined as death or hospitalization or unplanned urgent clinic visit due to device alarm of unknown significance or actual or threatening malfunction. Separate secondary outcomes were malfunction resulting in controller exchange and malfunction resulting in battery change. Exploratory outcomes were death, transplantation, or explantation because of recovery.

Results

Median age was 59 years and 19% were women. Over a mean follow-up time of 1.7 years (37 patient-years), the primary outcome occurred 30 times (0.8 events per patient-year; 0 deaths, 2 hospitalizations and 28 un-planned clinic visits). Secondary outcomes were 41 device malfunctions for 14 patients requiring 45 controller exchanges in 12 patients (1.1 events per patient-year) and 128 battery changes in 12 patients (3.5 events per patient-year). Exploratory outcomes were 8 deaths (36.4%), 7 transplantations (31.8%) and 2 explants due to recovery (9.1%).

Conclusion

The use of HVAD® was associated with technical problems requiring frequent un-planned clinic visits and changes of controller and/or batteries. There were no deaths due to device malfunction. Further studies are warranted to evaluate the risk of device malfunction and associated reductions in quality of life and cost.

Adverse Event Rates Change Favorably Over Time for Patients Bridged With the HeartWare Left Ventricular Assist Device

The HeartWare Ventricular Assist System (HVAD) provides significant improvements in survival and quality of life, and here, we seek to evaluate temporal differences in the adverse event (AE) rates. Patients (n = 382) in the ADVANCE bridge-to-transplant and continued access protocol trial were assessed for bleeding, cardiac arrhythmia, infection, ischemic and hemorrhagic stroke, and right heart failure during predetermined time periods (≤30, >30-180, >180-365, >365-730, >730-1,095 days) after HVAD implant. The Kaplan-Meier survival at 30 days, 6 months, 1, 2, and 3 years was 98%, 90%, 84%, 71%, and 63%, respectively. There were significantly fewer total AEs in days >30-180 (events per patient year [EPPY] = 5.34) compared with the first 30 days post HVAD implantation (EPPY = 30.36; p < 0.0001). The total AE rate in days >180-365 (EPPY = 4.09) was also significantly lower than the event rate in days >30-180 (EPPY = 5.34; p < 0.0001). Incidence of cardiac arrhythmias, infections, strokes, and right heart failure were highest immediately post implant and lower rates occurred after 6 months. After 1 year, all AEs exhibited stable rates that were comparable up to 3 years of support (all p > 0.05). This changing risk over time has clinically meaningful implications toward improving patient management.

A Decision Support System for the Treatment of Patients with Ventricular Assist Device Support

Background: Heart failure (HF) is affecting millions of people every year and it is characterized by impaired ventricular performance, exercise intolerance and shortened life expectancy. Despite significant advancements in drug therapy, mortality of the disease remains excessively high, as heart transplant remains the gold standard treatment for end-stage HF when no contraindications subsist. Traditionally, implanted Ventricular Assist Devices (VADs) have been employed in order to provide circulatory support to patients who cannot survive the waiting time to transplantation, reducing the workload imposed on the heart. In many cases that process could recover its contractility performance.

Objectives: The SensorART platform focuses on the management and remote treatment of patients suffering from HF. It provides an inter-operable, extendable and VAD-independent solution, which incorporates various hardware and software components in a holistic approach, in order to improve the quality of the patients’ treatment and the workflow of the specialists. This paper focuses on the description and analysis of Specialist’s Decision Support System (SDSS), an innovative component of the SensorART platform.

Methods: The SDSS is a Web-based tool that assists specialists on designing the therapy plan for their patients before and after VAD implantation, analyzing patients’ data, extracting new knowledge, and making informative decisions.

Results: SDSS offers support to medical and VAD experts through the different phases of VAD therapy, incorporating several tools covering all related fields; Statistics, Association Rules, Monitoring, Treatment, Weaning, Speed and Suction Detection.

Conclusions: SDSS and its modules have been tested in a number of patients and the results are encouraging.

Evaluation of the HeartWare ventricular assist device Lavare cycle in a particle image velocimetry model and in clinical practice

OBJECTIVES

Ventricular blood stasis is a concern for continuous flow mechanical support devices and might contribute to the formation of thromboembolic events. The HeartWare® Ventricular Assist System (HVAD®) is equipped with the Lavare™ cycle that is a periodic speed modulation feature designed to alter flow patterns within the left ventricle and reduce areas of potential blood stasis. Here, we report in vitro and clinical findings on the effects of the Lavare cycle.

METHODS

The effect of pump speed changes on the intraventricular flow field was examined with an in vitro particle image velocimetry model. The clinical impact of the Lavare cycle was evaluated through a retrospective review of the ReVOLVE study which includes 248 patients implanted with the HVAD following Conformité Européenne Mark in nine centres in Europe and Australia. Baseline characteristics, adverse event profiles and Kaplan-Meier survival estimates were stratified by patients using/not using the Lavare cycle.

RESULTS

Particle image velocimetry showed increased ventricular washout with an active Lavare cycle as measured by the fluid velocities and angular dispersion parameters. With the Lavare cycle on, there was also a 22% decrease in the stagnation index compared with when the Lavare cycle was off. In the ReVOLVE registry, patients with the Lavare cycle turned on (n = 215) were supported for 497 patient-years, whereas patients who did not use the speed modulation (n = 33) were supported for 39.3 patient-years. The Lavare cycle did not significantly affect patient survival as both groups had approximately an 80% survival after 1 year. Patients using the Lavare cycle had significantly fewer rates of stroke [0.06 vs 0.20 events per patient-year (EPPY), P = 0.0008], sepsis (0.03 vs 0.15 EPPY, P = 0.0003) and right heart failure (0.03 vs 0.18 EPPY, P < 0.0001) with no difference in the transplant or recovery rates among the two cohorts.

CONCLUSIONS

The Lavare cycle effectively generates ventricular washout and the adverse event profiles of ReVOLVE patients with the Lavare cycle on were better than those with the Lavare cycle off. Larger studies are warranted to verify the positive effect of the Lavare cycle and to optimize speed modulation settings, so additional clinically relevant improvements can be realized.

Mechanical Circulatory Support for the Failing Heart: Continuous-Flow Left Ventricular Assist Devices

BACKGROUND

Heart transplantation remains the definitive therapy for patients with advanced heart failure; however, owing to limited donor organ availability and long wait times, continuous-flow left ventricular assist devices (LVADs) have become standard therapy.

METHODS

This review summarizes the history, progression, function, and basic management of LVADs. Additionally, we provide some clinical pearls and important caveats for managing this unique patient population.

RESULTS

Currently, the most common LVADs being implanted in the United States are second- and third-generation devices, the HeartMate II (Thoratec Corp., St. Jude Medical) and the HeartWare HVAD (HeartWare International, Inc.). A newer third-generation pump, the HeartMate III (Thoratec Corp., St. Jude Medical), is designed to create an artificial pulse and is currently under investigation in the United States.

CONCLUSION

LVAD use is promising, will continue to grow, and has become standard therapy for advanced heart failure as a bridge to recovery, as destination therapy, and as a bridge to transplantation.

Left ventricular assist device management and complications

Patients on long-term left ventricular assist device (LVAD) support present unique challenges in the intensive care unit. It is crucial to know the status of end-organ perfusion, which may require invasive hemodynamic monitoring with a systemic arterial and pulmonary artery catheter. Depending on the indication for LVAD support (bridge to decision or cardiac transplantation vs destination therapy), it is important to readdress goals of care with the patient (if possible) and their family after major events have occurred that challenge the survival of the patient.

Left Ventricular Assist Devices in the Management of Heart Failure

Mechanical circulatory support has emerged as an important therapy for advanced heart failure, with more than 18,000 continuous flow devices implanted worldwide to date. These devices significantly improve survival and quality of life and should be considered in every patient with end-stage heart failure with reduced ejection fraction who has no other life-limiting diseases. All candidates for device implantation should undergo a thorough evaluation in order to identify those who could benefit from device implantation. Long-term management of ventricular assist device patients is challenging and requires knowledge of the characteristic complications with their unique clinical presentations.

Regional differences in use and outcomes of left ventricular assist devices: Insights from the Interagency Registry for Mechanically Assisted Circulatory Support Registry

BACKGROUND

We examined whether characteristics, implant strategy, and outcomes in patients who receive continuous-flow left ventricular assist devices (CF-LVAD) differ across geographic regions in the United States.

METHODS

A total of 7,404 CF-LVAD patients enrolled in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) from 134 participating institutions were analyzed from 4 distinct regions: Northeast, 2,605 (35%); Midwest, 2,210 (30%); West, 973 (13%); and South, 1,616 (22%).

RESULTS

At baseline, patients in the Northeast and South were more likely to have INTERMACS risk profiles 1 and 2. A bridge-to-transplant (BTT) strategy was more common in the Northeast (31.7%; West, 18.5%; South, 26.9%; Midwest, 25.5%; p < 0.0001). In contrast, destination therapy (DT) was more likely in the South (40.6%; Northeast, 32.3%; Midwest, 27.3%; West, 27.3%; p < 0.0001). Although all regions showed a high 1-year survival rate, some regional differences in long-term mortality were observed. Notably, survival beyond 1 year after LVAD implant was significantly lower in the South. However, when stratified by device strategy, no significant differences in survival for BTT or DT patients were found among the regions. Finally, with the exception of right ventricular failure, which was more common in the South, no other significant differences in causes of death were observed among the regions.

CONCLUSIONS

Regional differences in clinical profile and LVAD strategy exist in the United States. Despite an overall high survival rate at 1 year, differences in mortality among the regions were noted. The lower survival rate in the South may be attributed to patient characteristics and higher use of LVAD as DT.

A dynamic Bayesian network approach for time-specific survival probability prediction in patients after ventricular assist device implantation

In this work we present a decision support tool for the calculation of time-dependent survival probability for patients after ventricular assist device implantation. Two different models have been developed, a short term one which predicts survival for the first three months and a long term one that predicts survival for one year after implantation. In order to model the time dependencies between the different time slices of the problem, a dynamic Bayesian network (DBN) approach has been employed. DBNs order to capture the temporal events of the patient disease and the temporal data availability. High accuracy results have been reported for both models. The short and long term DBNs reached an accuracy of 96.97% and 93.55% respectively.

Results of the post-market Registry to Evaluate the HeartWare Left Ventricular Assist System (ReVOLVE)

BACKGROUND

The post-market Registry to Evaluate the HeartWare Left Ventricular Assist System (ReVOLVE) is an investigator-initiated registry established to collect post-CE Mark Trial clinical data on patients receiving a HeartWare ventricular assist device (HVAD) in the European Union and Australia.

METHODS

The ReVOLVE is a multi-center, prospective, single-arm registry performed at seven centers in Europe and two in Australia. Herein we describe a total of 254 commercial HVAD implants according to labeled indications between February 2009 and November 2012. Summary statistics included patients' demographics, adverse events, length of support and outcomes.

RESULTS

Compared with the clinical trial supporting the CE Mark of the HeartWare system, patient selection differed in that patients were older, and there were higher proportions of females and patients with idiopathic cardiomyopathies in the ReVOLVE cohort. Duration of support ranged from 1 to 1,057 days, with a mean of 363 ± 280 days (median 299.5 days). Transplantation was done in 56 patients (22%), explant for recovery was performed in 3 patients (1%), 43 died while on support (17%), and 152 (60%) remain on the device. Success in patients with the HeartWare system was 87% at 6 months, 85% at 1 year, 79% at 2 years and 73% at 3 years. Adverse event rates were low, comparable or improved when compared to the CE Mark Trial.

CONCLUSION

Real-world use of the HeartWare system continues to demonstrate excellent clinical outcomes in patients supported with the device.

Adverse event prediction in patients with left ventricular assist devices

This work presents the Treatment Tool, which is a component of the Specialist's Decision Support Framework (SDSS) of the SensorART platform. The SensorART platform focuses on the management of heart failure (HF) patients, which are treated with implantable, left ventricular assist devices (LVADs). SDSS supports the specialists on various decisions regarding patients with LVADs including decisions on the best treatment strategy, suggestion of the most appropriate candidates for LVAD weaning, configuration of the pump speed settings, while also provides data analysis tools for new knowledge extraction. The Treatment Tool is a web-based component and its functionality includes the calculation of several acknowledged risk scores along with the adverse events appearance prediction for treatment assessment.

Impact of adverse events on ventricular assist device outcomes

Left ventricular assist devices have been proven to be superior to medical therapy for advanced heart failure patients awaiting heart transplantation and viable alternatives to transplantation for destination therapy patients. Improvements in the design of ventricular assist devices have been rewarded by a decrease in adverse events and an increase in survival. Despite significant progress, even the latest generation left ventricular assist devices are burdened by a significant long-term adverse events profile that will increasingly challenge physicians as patients survive longer on implantable mechanical circulatory support. In this review, we analyze the impact of long-term adverse events on clinical outcomes in the major trials of continuous flow left ventricular assist devices. We discuss several of the more pertinent and interesting adverse events, examine their potential causes, and explore their future implications.

Advances and future directions for mechanical circulatory support

Although cardiac transplant remains the gold standard for the treatment of end-stage heart failure, limited donor organ availability and growing numbers of eligible recipients have increased the demand for alternative therapies. Limitations of first-generation left ventricular assist devices for long-term support of patients with end-stage disease have led to the development of newer second-generation and third-generation pumps, which are smaller, have fewer moving parts, and have shown improved durability, allowing for extended support. The HeartMate II (second generation) and HeartWare (third generation) are 2 devices that have shown great promise as potential alternatives to transplantation in select patients.

High peripheral levels of h-FABP are associated with poor prognosis in end-stage heart failure patients with mechanical circulatory support

Aim: To associate the time-course of h-FABP and N-terminal pro B-type natriuretic peptide (NT-proBNP)after left ventricular assist device (LVAD) implantation to outcome in end-stage heart failure patients. Materials & methods: Patients (n = 14, NYHA class III/IV; left ventricular ejection fraction <25% were enrolled; ten survived up to 1 month after LVAD (survivors) and four died of multiorgan failure within 2 weeks (nonsurvivors). Blood samples were obtained at admission; at 4, 24 and 72 h; and at 1 and 4 weeks after LVAD. Results: h-FABP significantly increases after surgery, decreasing since 72 h in all patients. At 72 h all survivor patients present h-FABP lower than the median value. N-terminal pro B-type natriuretic peptide is not associated with patient outcome at any time. Conclusion: High h-FABP levels, indicating the presence of more severe myocardial damage, are associated with a poor prognosis in patients with LVAD, suggesting that an early cardiac injury marker could improve the prediction of clinical outcome.

Berlin Heart EXCOR pediatric ventricular assist device for bridge to heart transplantation in US children

BACKGROUND

Recent data suggest that the Berlin Heart EXCOR Pediatric ventricular assist device is superior to extracorporeal membrane oxygenation for bridge to heart transplantation. Published data are limited to 1 in 4 children who received the device as part of the US clinical trial. We analyzed outcomes for all US children who received the EXCOR to characterize device outcomes in an unselected cohort and to identify risk factors for mortality to facilitate patient selection.

METHODS AND RESULTS

This multicenter, prospective cohort study involved all children implanted with the Berlin Heart EXCOR Pediatric ventricular assist device at 47 centers from May 2007 through December 2010. Multiphase nonproportional hazards modeling was used to identify risk factors for early (<2 months) and late mortality. Of 204 children supported with the EXCOR, the median duration of support was 40 days (range, 1-435 days). Survival at 12 months was 75%, including 64% who reached transplantation, 6% who recovered, and 5% who were alive on the device. Multivariable analysis identified lower weight, biventricular assist device support, and elevated bilirubin as risk factors for early mortality and bilirubin extremes and renal dysfunction as risk factors for late mortality. Neurological dysfunction occurred in 29% and was the leading cause of death.

CONCLUSIONS

Use of the Berlin Heart EXCOR has risen dramatically over the past decade. The EXCOR has emerged as a new treatment standard in the United States for pediatric bridge to transplantation. Three-quarters of children survived to transplantation or recovery; an important fraction experienced neurological dysfunction. Smaller patient size, renal dysfunction, hepatic dysfunction, and biventricular assist device use were associated with mortality, whereas extracorporeal membrane oxygenation before implantation and congenital heart disease were not.

Patient selection for ventricular assist devices: a moving target

The number of patients with advanced heart failure that has become unresponsive to conventional medical therapy is increasing rapidly. One of the most promising new alternatives to heart transplantation is use of ventricular assist devices (VADs). To date, there are no guidelines for appropriate selection for use of these devices that are approved by national societies in the field. This review addresses all of the general criteria for clinicians to keep in mind regarding when to refer a patient for evaluation and the specific issues addressed in patient selection. The field of mechanical circulatory support has advanced significantly over the past 10 years, resulting in rapid expansion of patients with advanced heart failure who can benefit from implantable devices. With progress of technology, limitations associated with age, body size, and comorbidities gradually become less prohibitive. The continuing simplification of design along with continued reduction in size of the devices, plus eventual elimination of the external drive line will make the use of VADs a superior option to heart transplant and even to medical management in many patients. We anticipate that the patient selection process outlined in the present review will continue to shift toward less advanced cases of heart failure.

Fluoroscopy-guided resolution of ingested thrombus leading to functional disturbance of a continuous-flow left ventricular assist device

The third generation of left ventricular assist devices (LVADs) has been shown to improve outcome and quality of life in patients suffering from acute and chronic heart failure. However, VAD-associated complications are still a challenge in the clinical practice. Here we report the resolution of a mobile thrombus formation in the proximity of the inflow cannula of a third generation of LVADs (HVAD Pump, HeartWare, Inc.) in a patient with chronic heart failure 4 months after implantation.

The pharmacotherapy implications of ventricular assist device in the patient with end-stage heart failure

Advances in mechanical circulatory support, such as the use of ventricular assist devices (VADs), have become a means for prolonging survival in end-stage heart failure (HF). VADs decrease the symptoms of HF and improve quality of life by replacing some of the work of a failing heart. They unload the ventricle to provide improved cardiac output and end-organ perfusion, resulting in improvement in cardiorenal syndromes and New York Heart Association functional class rating. VADs are currently used asa bridge to heart transplantation, a bridge to recovery of cardiac function, or as destination therapy. Complications of VAD include bleeding, infections, arrhythmias, multiple organ failure, right ventricular failure, and neurological dysfunction. Patients with VAD have unique pharmacotherapeutic requirements in terms of anticoagulation, appropriate antibiotic selection, and continuation of HF medications. Pharmacists in acute care and community settings are well prepared to care for the patient with VAD. These patients require thorough counseling and follow-up with regard to prevention and treatment of infections, appropriate levels of anticoagulation, and maintenance of fluid balance. A basic understanding of this unique therapy can assist pharmacists in attending to the needs of patients with VAD.

Mechanical assistance of the circulation during cardiogenic shock

PURPOSE OF REVIEW

Cardiogenic shock still has a grave prognosis. We present the recent advances in mechanical circulatory support (MCS) for the treatment of refractory cardiogenic shock.

RECENT FINDINGS

The contraindications for short-term MCS in rapid-onset cardiogenic shock are becoming fewer and the threshold for its application has been progressively lowered. Short-term MCS is increasingly used in refractory cardiac arrest and will be probably integrated as the last means in the advanced cardiopulmonary resuscitation algorithm (provided there is experienced team and technical support). Improved device technology has contributed to improved results of long-term MCS. Emergent application of long-term MCS in patients with critical cardiogenic shock after a long history of progressively deteriorating end-stage chronic heart failure should be interpreted as delayed application associated with increased mortality.

SUMMARY

Although MCS can be life saving in cardiogenic shock, the results are still suboptimal. Mortality is associated with the critical presupport state and the adverse events during MCS. Early initiation of support that meets the patient's requirements, potent support in the early phase, adverse event prevention, global combined management (surgical, interventional, medical), balanced support duration, bridging to further therapeutic modalities including heart transplantation or longer-term support, and advanced technology could offer improved results.

Association of pre-operative interleukin-6 levels with Interagency Registry for Mechanically Assisted Circulatory Support profiles and intensive care unit stay in left ventricular assist device patients

BACKGROUND

Inflammatory mechanisms are associated with worse prognosis in end-stage heart failure (ESHF) patients who require left ventricular assist device (LVAD) support. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profiles describe patient condition at pre-implant and outcome. This study assessed the relationship among inflammation patterns and INTERMACS profiles in LVAD recipients.

METHOD

Thirty ESHF patients undergoing LVAD implantation as bridge to transplant were enrolled. Blood and urine samples were collected pre-operatively and serially up to 2 weeks post-operatively for assessment of inflammatory markers (plasma levels of interleukin [IL]-6, IL-8, IL-10, and osteopontin, a cardiac inflammatory-remodeling marker; and the urine neopterin/creatinine ratio, a monocyte activation marker). Multiorgan function was evaluated by the total sequential organ failure assessment (tSOFA) score. Outcomes of interest were early survival, post-LVAD tSOFA score, and intensive care unit (ICU) length of stay.

RESULTS

Fifteen patients had INTERMACS profiles 1 or 2 (Group A), and 15 had profiles 3 or 4 (Group B). At pre-implant, only IL-6 levels and the IL-6/IL-10 ratio were higher in Group A vs B. After LVAD implantation, neopterin/creatinine ratio and IL-8 levels increased more in Group A vs B. Osteopontin levels increased significantly only in Group B. The tSOFA score at 2 weeks post-LVAD and ICU duration were related with pre-implant IL-6 levels.

CONCLUSIONS

The INTERMACS profiles reflect the severity of the pre-operative inflammatory activation and the post-implant inflammatory response, affecting post-operative tSOFA score and ICU stay. Therefore, inflammation may contribute to poor outcome in patients with severe INTERMACS profile.

Long-term continuous flow left ventricular assist device support and end-organ function: prospects for destination therapy

Pulsatile flow left ventricular assist devices (PF-LVADs) have successfully supported patients with severe heart failure for bridge-to-transplant (BTT) and destination therapy (DT). End-organ dysfunction is often reversed, optimizing the patient's condition to enhance survival, and quality of life. Questions have been raised regarding the potential for continuous flow LVADs (CF-LVADs) to provide the same quality of circulatory support. Prior research showing that PF is superior to continuous, non-PF does not appear to be relevant with CF-LVADs for BTT and DT. Under most clinical conditions, arterial pulsatility is present during CF-LVAD support, and this type of support should not be termed "nonpulsatile." Clinical studies have shown that renal, hepatic, and neurocognitive function is either maintained within a normal range, or is significantly improved, during CF-LVAD support for durations up to 15 months. Results of the randomized clinical trial between the CF HeartMate II and the pulsatile HeartMate XVE (both by Thoratec Corp, Pleasanton, CA, USA) are pending final US Food and Drug Administration (FDA) review and are not yet published. Studies of microcirculation during CF-LVAD support indicate that capillary blood flow is adequate to support cellular function. There are anecdotal cases of patients being supported with a CF-LVAD for over seven years with preserved end-organ function. Presently, there are no clinical reports indicating that end-organ function is not well maintained. Current clinical evidence indicates that end-organ perfusion and function can be well maintained for extended durations of support with a CF-LVAD.

Results of mechanical circulatory support in France

OBJECTIVE

To present the analyzed results on mechanical circulatory support (MCS) collected over a 7-year period, from 2000 to 2006, in France.

METHODS

A cohort of 520 patients was analyzed. Mean age was 43.7 ± 13.6 years. The main causes of cardiac failure were ischemic cardiomyopathy (39%), idiopathic dilated cardiomyopathy (41.3%), or myocarditis (6.4%). Bridge to transplantation was indicated in 87.8% of patients, bridge to recovery in 9%, while destination therapy was proposed in 3.2% of patients.

RESULTS

For patients in cardiogenic shock or advanced heart failure undergoing device implantation as bridge to transplantation or recovery (n=458), overall mortality was 39% (n=179). The main causes of mortality under MCS were multi-organ failure (MOF) (57.4%), neurological events (14.1%), or infections (11.9%). Heart transplantation was performed in 249 (54.3%) patients. The main causes of death following heart transplantation were primary graft failure (22.4%), MOF (14.3%), neurological event (14.3%), or infection (10.2%). Long-term survival in transplanted patients was 75 ± 2.8% at 1 year and 66 ± 3.4% at 5 years.

CONCLUSIONS

MCS is an essential therapeutic tool to save the life of young patients with cardiogenic shock or advanced cardiac failure. Early MCS implantation and the availability of a device that is adapted to the patient's clinical status are prerequisites for reducing overall mortality rates.

Transapical miniaturized ventricular assist device: design and initial testing

BACKGROUND

Left ventricular assist devices are increasingly used to treat patients with advanced and otherwise refractory heart failure as bridge to transplant or destination therapy. We evaluated a new miniaturized left ventricular assist device that requires minimal surgery for implantation, potentially allowing implantation in earlier stage heart failure.

METHODS

HeartWare (Miami Lakes, Fla) developed transapical miniaturized ventricular assist device. Acute (n = 4), 1-week (n = 2), and 30-day (n = 4) bovine model experiments evaluated hemodynamic efficacy and biocompatibility of the device, which was implanted through small left thoracotomy with single insertion at apex of left ventricle without cardiopulmonary bypass. The device outflow cannula was positioned across the aortic valve. The international normalized ratio was maintained between 2.0 and 2.5 with warfarin. Hemodynamic, echocardiographic, fluoroscopic, hematologic, and blood chemistry measurements were evaluated.

RESULTS

The device was successfully implanted through the left ventricular apex in all 10 animals. The device was operated at 15,000 ± 1000 rpm (power consumption, 3.5-6.0 W). The device maintained normal end-organ perfusion with no significant hemolysis (0-30 mg/dL). There were no pump failures or device-related complications. At autopsy, no abnormalities were seen in endocardium, aortic valve leaflets, or aortic root. There was no evidence of thromboembolism or abnormalities in any peripheral end organs.

CONCLUSIONS

We successfully demonstrated feasibility of a novel intraventricular assist device that can be completely implanted through left ventricular apex. This transapical surgical approach eliminates needs for sternotomy, device pocket, cardiopulmonary bypass, ventricular coring, and construction of an outflow graft anastomosis.

Usefulness of the INTERMACS Scale for predicting outcomes after urgent heart transplantation

INTRODUCTION AND OBJECTIVES

Our aim was to assess the prognostic value of the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) scale in patients undergoing urgent heart transplantation (HT).

METHODS

Retrospective analysis of 111 patients treated with urgent HT at our institution from April, 1991 to October, 2009. Patients were retrospectively assigned to three levels of the INTERMACS scale according to their clinical status before HT.

RESULTS

Patients at the INTERMACS 1 level (n=31) more frequently had ischemic heart disease (P=.03) and post-cardiothomy shock (P=.02) than patients at the INTERMACS 2 (n=55) and INTERMACS 3-4 (n=25) levels. Patients at the INTERMACS 1 level showed higher preoperative catecolamin doses (P=.001), a higher frequency of use of mechanical ventilation (P<.001), intraaortic balloon (P=.002) and ventricular assist devices (P=.002), and a higher frequency of preoperative infection (P=.015). The INTERMACS 1 group also presented higher central venous pressure (P=.02), AST (P=.002), ALT (P=.006) and serum creatinine (P<.001), and lower hemoglobin (P=.008) and creatinine clearance (P=.001). After HT, patients at the INTERMACS 1 level had a higher incidence of primary graft failure (P=.03) and postoperative need for renal replacement therapy (P=.004), and their long-term survival was lower than patients at the INTERMACS 2 (log rank 5.1, P=.023; HR 3.1, IC 95% 1.1-8.8) and INTERMACS 3-4 level (log rank 6.1, p=0.013; HR 6.8, IC 95% 1.2-39.1).

CONCLUSIONS

Our results suggest that the INTERMACS scale may be a useful tool to stratify postoperative prognosis after urgent HT.

Clinical outcomes for continuous-flow left ventricular assist device patients stratified by pre-operative INTERMACS classification

BACKGROUND

Risk stratification for mechanical circulatory support (MCS) has emerged as an important tool in patient selection and outcomes assessment. Most studies examining risk stratification have been limited to pulsatile devices. We use the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) to stratify patients with continuous-flow devices and assess outcomes in less severe, but functionally impaired, heart failure patients.

METHODS

This study included 101 bridge-to-transplant and destination-therapy patients at 3 centers. Three groups were studied: Group 1, cardiogenic shock (INTERMACS Profile 1); Group 2, inotrope-dependent (INTERMACS Profile 2 or 3); and Group 3, ambulatory advanced heart failure (INTERMACS Profiles 4 to 7). The outcomes of interest were actuarial survival, survival to discharge and length of stay.

RESULTS

Survival at 36 months was better in Group 3 than in Group 1 (95.8% vs 51.1%, p = 0.011), but not between Groups 2 and 3 (68.8 vs 95.8%, p = 0.065). Lengths of stay for Groups 1 to 3 were 44, 41 and 17 days: Groups 1 vs 3, p < 0.001; Groups 2 vs 3, p < 0.001; and Groups 1 vs 2, p = 0.62. Lengths of stay for survivors were 49, 39 and 14 for the 3 groups: Groups 1 vs 3, p < 0.001; Groups 2 vs 3, p < 0.001; and Groups 1 vs 2, p = 0.28.

CONCLUSION

INTERMACS classification is a useful metric for risk-stratifying candidates for MCS. Less acutely ill but functionally impaired heart failure patients receiving continuous-flow LVADs had longer short- and long-term survival and shorter lengths of stay compared with patients who were more acutely ill.

Automated surveillance to detect postprocedure safety signals of approved cardiovascular devices

CONTEXT

Ensuring the safety of medical devices challenges current surveillance approaches, which rely heavily on voluntary reporting of adverse events. Automated surveillance of clinical registries may provide early warnings in the postmarket evaluation of medical device safety.

OBJECTIVE

To determine whether automated safety surveillance of clinical registries using a computerized tool can provide early warnings regarding the safety of new cardiovascular devices.

DESIGN, SETTING, AND PATIENTS

Prospective propensity-matched cohort analysis of 7 newly introduced cardiovascular devices, using clinical data captured in the Massachusetts implementation of the National Cardiovascular Data Repository CathPCI Registry for all adult patients undergoing percutaneous coronary intervention from April 2003 through September 2007 in Massachusetts.

MAIN OUTCOME MEASURE

Presence of any safety alert, triggered if the cumulative observed risk for a given device exceeded the upper 95% confidence interval (CI) of comparator control device. Predefined sensitivity analyses assessed robustness of alerts when triggered.

RESULTS

We evaluated 74,427 consecutive interventional coronary procedures. Three of 21 safety analyses triggered sustained alerts in 2 implantable devices. Patients receiving Taxus Express2 drug-eluting stents experienced a 1.28-fold increased risk of postprocedural myocardial infarction (2.87% vs 2.25%; absolute risk increase, 0.62% [95% CI, 0.25%-0.99%]) and a 1.21-fold increased risk of major adverse cardiac events (4.24% vs 3.50%; absolute increase, 0.74% [95% CI, 0.29%-1.19%]) compared with those receiving alternative drug-eluting stents. Patients receiving Angio-Seal STS vascular closure devices experienced a 1.51-fold increased risk of major vascular complications (1.09% vs 0.72%; absolute increased risk, 0.37% [95% CI, 0.03%-0.71%]) compared with those receiving alternative vascular closure devices. Sensitivity analyses confirmed increased risk following use of the Taxus Express2 stent but not the Angio-Seal STS device.

CONCLUSION

Automated prospective surveillance of clinical registries is feasible and can identify low-frequency safety signals for new cardiovascular devices.