Field Of Mechanical Circulatory Support Research Articles

Physical Properties of Blood and their Relationship to Clinical Conditions.

It has been long known that blood health heavily influences optimal physiological function. Abnormalities affecting the physical properties of blood have been implicated in the pathogenesis of various disorders, although the exact mechanistic links between hemorheology and clinical disease manifestations remain poorly understood. Often overlooked in current medical practice, perhaps due to the promises offered in the molecular and genetic era, the physical properties of blood which remain a valuable and definitive indicator of circulatory health and disease. Bridging this gap, the current manuscript provides an introduction to hemorheology. It reviews the properties that dictate bulk and microcirculatory flow by systematically dissecting the biomechanics that determine the non-Newtonian behavior of blood. Specifically, the impact of hematocrit, the mechanical properties and tendency of red blood cells to aggregate, and various plasma factors on blood viscosity will be examined. Subsequently, the manner in which the physical properties of blood influence hemodynamics in health and disease is discussed. Special attention is given to disorders such as sickle cell disease, emphasizing the clinical impact of severely abnormal blood rheology. This review expands into concepts that are highly topical; the relation between mechanical stress and intracellular homeostasis is examined through a contemporary cell-signaling lens. Indeed, accumulating evidence demonstrates that nitric oxide is not only transported by erythrocytes, but is locally produced by mechanically-sensitive enzymes, which appears to have intracellular and potentially extracellular effects. Finally, given the importance of shear forces in the developing field of mechanical circulatory support, we review the role of blood rheology in temporary and durable mechanical circulatory support devices, an increasingly utilized method of life support. This review thus provides a comprehensive overview for interested trainees, scientists, and clinicians.

Hospital Outcomes in LVAD Therapy: Can We Benchmark Performance and Preserve Disruptive Innovation?

In this issue of The Annals of Thoracic Surgery, Pienta and colleagues1 provide an important analysis of benchmarking hospital performance in the field of mechanical circulatory support (MCS). The variability in outcomes (observed to expected ratio, 0-6 for 90-day mortality) provides an opportunity to reflect about both the interpretation of such variability and how this information should be used to examine performance and provide quality assurance.

Insights from the thoracic surgery residents association early-career development series

Insights from the thoracic surgery residents association early-career development series

The ever-changing field of mechanical circulatory support: new challenges at the advent of the 'single device era'.

The ever-changing field of mechanical circulatory support: new challenges at the advent of the 'single device era'.

Anticoagulation in Mechanical Circulatory Support

The field of mechanical circulatory support is rapidly evolving, and along with it, the management of anticoagulation and hemocompatibility also changes. The purpose of this review is to provide a contemporary approach to the evaluation and management of anticoagulation in mechanical circulatory support device therapies. Important recent studies and guidelines have solidified a more uniform approach to anticoagulation in both temporary and durable devices. With advances in technology, it may be possible to reduce the requirements for anticoagulant and antiplatelet therapies. Though there are new technologies and management strategies being utilized, hemocompatibility between a patient and their mechanical circulatory support device remains of paramount importance for acceptable outcomes after device implantation. This must be individualized to each patient and performed within the context of a dedicated multidisciplinary team.

Evolution and clinical adoption of the Autologs system: An automated analysis for enhanced patient management in MCS.

The Medtronic Autologs System allows real-time clinician review of HeartWare HVAD System logfiles, providing supplemental pump data to aid in patient management. In its first year of availability, Autologs generated a 70% increase in logfile submissions, with 73% of all logfile requests being sent to Autologs. Within a month of its launch, Autologs submissions outnumbered the amount of logfiles submitted for manual review. Following the v1.1 release, there was a 20% increase in logfile submissions, with 77% of all logfile requests being Autologs. With the introduction of v1.2, there was another 35% increase in logfile submissions, with nearly 90% of all logfile requests being Autologs. The widespread adoption and utility of the Autologs System highlights the need for clinician access to real-time data analysis in the field of Mechanical Circulatory Support.

The Society of Thoracic Surgeons Intermacs 2019 Annual Report: The Changing Landscape of Devices and Indications

The field of mechanical circulatory support has been impacted by the approval of new continuous-flow left ventricular assist devices (LVADs) and changes to the United States heart allocation system. Primary isolated continuous-flow LVAD implants in The Society of Thoracic Surgeons Intermacs registry from January 2014 through September 2019 were evaluated. Survival and freedom from major adverse events were compared between axial-flow, centrifugal-flow with hybrid levitation (CF-HL), and centrifugal-flow with full magnetic levitation (CF-FML) devices. Of 2603 devices implanted in 2014, 1824 (70.1%) were axial flow and 1213 (46.6%) were destination therapy (DT); through September 2019, 1752 devices were implanted, but only 37 (2.1%) were axial flow and 1230 (70.2%) were DT. Implants were performed in 13,016 patients between 2014 and 2018. Patients receiving implants in 2017-2018 compared with 2014-2016 were more likely to be at Intermacs profile 1 (17.1% vs 14.3%, P < .001) and to have preimplant temporary mechanical circulatory support (34.8% vs 29.3%, P < .001). Overall survival and freedom from major adverse events were higher with CF-FML devices. In multivariable analysis ofsurvival between CF-HL and CF-FML, device type wasnot a significant early hazard, but the use of CF-HL devices had a late hazard ratio for death of 3.01 (P<.001). Over the past 5 years, centrifugal-flow LVADs have become the dominant technology and DT the most common implant strategy. While outcomes with CF-FML devices are promising, comparisons with other devices from nonrandomized registry studies should be made with caution.

Mechanical circulatory support in children: past, present and future.

Rapid advances in the field of mechanical circulatory support (MCS) have dramatically changed the management of pediatric patients with heart failure. There is now emphasis on timely implantation of ventricular assist devices (VADs) to preserve or recover end-organ function, and increased focus on post-implant management to improve the stroke rate. Transplant waitlist mortality has significantly decreased in the era of VAD use. Devices approved for adults are being used off-label in children with excellent outcomes, allowing chronic therapy and discharge home to become part of pediatric VAD therapy.

Current perspectives on mechanical circulatory support.

Summary Mechanical circulatory support gained a significant value in the armamentarium of heart failure therapy because of the increased awareness of the prevalence of heart failure and the tremendous advances in the field of mechanical circulatory support during the last decades. Current device technologies already complement a heart transplant as the gold standard of treatment for patients with end-stage heart failure refractory to conservative medical therapy. This article reviews important aspects of mechanical circulatory support therapy and focuses on currently debated issues.

Kenneth Clark Butler (1939–2018)

Kenneth Clark Butler (1939–2018)

Invited Commentary

The establishment of The Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) in 2005 was an important step forward for the community of medical providers who are involved in the field of mechanical circulatory support (MCS). For the first time, a large database was established to serve as a repository for all variables affecting patients receiving MCS. The mandate by the regulatory agencies (notably the Joint Commission) to require all programs performing device implantation to benchmark against Intermacs had the added benefit of incentivizing programs in the United States to make substantial internal investments to collect, track, and report their data accurately. On January 1, 2018, oversight and coordination of Intermacs moved to The Society of Thoracic Surgeons (STS) National Database. The incorporation of this database into the larger STS Council on Quality, Research, and Patient Safety will provide additional resources for detailed data collection, analysis, and scientific inquiry similar to the quality work that has emerged from the larger STS databases in cardiac, thoracic, and congenital surgery. In this issue of The Annals of Thoracic Surgery, Kormos and colleagues [1Kormos R.L. Cowger J. Pagani F.D. et al.The Society of Thoracic Surgeons Intermacs Database Annual Report: evolving indications, outcomes, and scientific partnerships.Ann Thorac Surg. 2019; 107: 341-354Abstract Full Text Full Text PDF PubMed Scopus (140) Google Scholar] have produced the annual report on the data from Intermacs. This report primarily focuses on documenting the outcomes of patients undergoing durable left ventricular assist device with the use of Food and Drug Administration-approved, continuous flow rotary pumps. One of the more interesting data points is the documentation of the shift from axial flow pumps to centrifugal flow pumps. This transition likely represents the natural history of pump implant choices that follow advances in technology with each new generation of devices. This report also continues to highlight the limitations of the current device technology; namely neurologic events, gastrointestinal bleeding, and infections. These remain the areas in need of the greatest improvement for caring for these patients and provide the benchmark by which each individual program should use in evaluating their outcomes. In addition, note that these data have traditionally been published in the Journal of Heart and Lung Transplantation that has a more generalized readership among transplant cardiologists, nursing professionals, pharmacists, and other disciplines. Thus, it is critical that we ensure that the publication of this data be widely accessible to the other members of the heart failure community and not restricted to the STS membership with a paid subscription. Similarly, with new leadership will come the daunting task of ensuring that these safeguarded data are easily accessible to other members in the discipline of MCS for research and analysis. With the STS now behind the database, we expect further scientific inquiries and scrutinized analyzes will continue to improve the outcomes for patients with end-stage heart failure for years to come. The Society of Thoracic Surgeons Intermacs Database Annual Report: Evolving Indications, Outcomes, and Scientific PartnershipsThe Annals of Thoracic SurgeryVol. 107Issue 2PreviewThe Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs), a joint effort among the National Heart, Lung, and Blood Institute, the Food and Drug Administration, the Centers for Medicare and Medicaid Services, and others, was established in 2005 at the University of Alabama at Birmingham. The registry examined clinical outcomes and quality-of-life metrics of patients who received an Food and Drug Administration-approved durable mechanical circulatory support (MCS) device to treat advanced heart failure. Full-Text PDF

The Evolution of Mechanical Circulatory Support.

The field of mechanical circulatory support (MCS) has evolved from earlier-generation pulsatile-flow devices that were primarily used to support critically ill patients in the hospital to newer-generation continuous-flow devices that permit hospital discharge and resumption of normal life activities. The technology is used to bridge transplant-eligible patients and can be used for long-term support of patients who are transplant ineligible. Left ventricular assist devices are proved to improve long-term survival and quality of life for patients with advanced heart failure. Adverse events associated with MCS therapy remain the Achilles heel of the field and strategies to improve biocompatibility are ongoing.

What Did We Learn about VADs in 2017?

The field of mechanical circulatory support is evolving rapidly and new data are published at a rate which can be overwhelming. For the last three years, we published annual reviews of the current literature entitled “What Did We Learn about VADs?” in the past year (1-3). All three papers were well received as the full texts were downloaded 704, 676 and 413 times, respectively, by the readers around the globe. Continuing the tradition, we have written the present review and as with all previous reviews, we summarized some publications from 2017 that we think are of particular importance and interest. There may be some slight overlap with the end of 2016 due to some papers having been published online first.

Current concepts for sensitized patients before transplantation.

Antibody allosensitization poses a major immunologic challenge for patients awaiting heart transplantation. It is associated with significant morbidity and mortality for both pretransplant and posttransplant patients by prolonging wait times to transplant and increasing posttransplant rejection and vasculopathy. Many questions remain regarding methods and interpretation of antibody detection, the relevance of sensitization in specific patient populations such as those with mechanical circulatory support and the ideal strategies for desensitization. More sensitive and specific assays are now available to help identify and risk stratify highly sensitized patients. The growing field of mechanical circulatory support is introducing new questions and observations about sensitization in patients supported by ventricular-assist devices. Multiple desensitization therapies, including newer treatments such as bortezomib and eculizumab, targeting various components of the humoral immune response, appear to show promise by significantly reducing allosensitization and allowing for successful transplantation with good outcomes. The development of more accurate methods of detecting sensitization and defining the ideal desensitization strategies that can be more universally adopted and tested in clinical trials will serve to enlighten us and help many more highly sensitized patients not only make it to transplant, but also thrive posttransplant as well.

Pediatric ventricular assist devices: current challenges and future prospects.

The field of mechanical circulatory support has made great strides in the preceding 2 decades. Although pediatric mechanical circulatory support has lagged behind that of adults, the gap between them is expected to close soon. The only device currently approved by the US Food and Drug Administration for use in children is the Berlin Heart EXCOR ventricular assist device (VAD). The prospective Berlin Heart Investigational Device Exemption Trial demonstrated good outcomes, such as bridge to transplantation or recovery, in ~90% of children supported with this device. However, a high incidence of hemorrhagic and thrombotic complications was also noted. As a result, pediatric centers have just started implanting adult intracorporeal continuous-flow devices in children. This paradigm shift has opened a new era in pediatric mechanical circulatory support. Whereas children on VAD were previously managed exclusively in hospital, therapeutic options such as outpatient management and even destination therapy have been becoming a reality. With continued miniaturization and technological refinements, devices currently in development will broaden the range of options available to children. The HeartMate 3 and HeartWare MVAD are two such compact VADs, which are anticipated to have great potential for pediatric use. Additionally, a pediatric-specific continuous-flow VAD, the newly redesigned Jarvik Infant 2015, is currently undergoing preclinical testing and is expected to undergo a randomized clinical trial in the near future. This review aims to discuss the challenges posed by the use of intracorporeal adult continuous-flow devices in children, as well as to provide our perspective on the future prospects of the field of pediatric VADs.

What Did We Learn about VADs in 2016?

&#x0D; &#x0D; &#x0D; The field of mechanical circulatory support is evolving rapidly and new data are published at a rate that can be overwhelming. The last two years, we published reviews entitled “What Did We Learn about VADs in 2014?”(1) and “What Did We Learn about VADs in 2015?”(2). Both papers were well received – the full texts were downloaded 570 and 440 times, respectively, by readers around the globe. Encouraged by this, we wrote the present review, where, like before, we summarized some of the publications from 2016 that we think are particularly important. There may be slight overlap with the end of 2015, because some papers are being published online first.&#x0D; &#x0D; &#x0D;

What Did We Learn about VADs in 2015?

&#x0D; &#x0D; &#x0D; The field of mechanical circulatory support is rapidly evolving and new data are published at a rate that can be overwhelming. Last year, we published a review paper entitled “What Did We Learn about VADs in 2014?” That paper was well received – the full text was downloaded over 350 times by the readers around the globe. Encouraged by this, we wrote the present review, where, like before, we summarized some of the publications from 2015 that we think are particularly important.&#x0D; &#x0D; &#x0D;

Left ventricular assist device implantation strategies and outcomes.

Over the past 15 years, the field of mechanical circulatory support has developed significantly. Currently, there are a multitude of options for both short and long term cardiac support. Choosing the appropriate device for each patient depends on the amount of support needed and the goals of care. This article focuses on long term, implantable devices for both bridge to transplantation and destination therapy indications. Implantation strategies, including the appropriate concomitant surgeries are discussed as well as expected long term outcomes. As device technology continues to improve, long term mechanical circulatory support may become a viable alternative to transplantation.

What Did We Learn About VADs in 2014?

The field of mechanical circulatory support is evolving rapidly and new data are published at a rate that can be overwhelming. In this review, we summarized some of the publications from 2014 that we think are particularly important. We have also included a few selected papers from the end of 2013 and the very beginning of 2015. Some of this overlap reflects the inevitable delay between online and paper publications. Readers who wish to supplement this review or argue with the author’s statements are encouraged to do so on our Facebook page at https://www.facebook.com/TheVADJournal.

Management of pump thrombosis in patients with left ventricular assist devices.

The gradual evolution of left ventricular assist device (LVAD) therapy has resulted in a durable option for patients as either a bridge to transplantation (BTT) or a destination therapy (DT). Outcomes with current continuous-flow devices continue to demonstrate significant patient benefit, not only in enhanced survival but also in improved functional capacity and quality of life. While the lessening of adverse events through time has resulted in more widespread adoption of this therapy, there continues to be unintended consequences, including, most notably, infection, bleeding, and thrombosis. Beginning in 2011, centers and collaborative groups began to observe a significant increase in the incidence of pump thrombosis with the HeartMate II LVAD (Thoratec Corp., Pleasanton, CA, USA). However, this clinical scourge is not limited to the HeartMate II, as the HeartWare Ventricular Assist System (HVAD; HeartWare Inc., Framingham, MA, USA) has also had these same issues, which led to pump modifications and the appreciation of more strict control of blood pressure and anticoagulation with this pump design. We review the current status of the field of mechanical circulatory support in its approach to diagnosis, management, and prevention of LVAD pump thrombosis.