Current state of ventricular assist devices

Significance of right ventricular function for the outcome of treatment and remodeling of the heart after left ventricular assist device implantation

The efficiency of the device for permanent circulatory support of the left ventricle has been proven through clinical practice with the trend of constant improvement of treatment results along with biotechnological progress and improvement of surgical implantation techniques. The published reports of most reference cardiac surgery centers present a one-year survival rate of over 85%, a two-year survival rate of 70% and a five-year survival rate of 45-50%. In addition to clear benefits for the patient, implantation of LVAD also carries significant specific risks, so infections, post-implantation bleeding, strokes, and right ventricular postimplantation weakness are the most common complications. Given that the progress of the LVAD program is ensured primarily by reducing the incidence of complications not related to the functioning of individual segments of the cardiovascular system, and as left ventricular function is completely replaced by LVAD device, the most recent challenge is the decision to install LVAD device in the heart with right ventricular, given that the postimplantation weakness of right ventricular is associated with proven increased mortality and morbidity. Since the 1990s, studies on hearts with implanted LVAD as a bridge to heart transplantation have shown regression of cell hypertrophy, normalization of cell size, muscle fiber architecture, and heart chamber geometry. The described changes are characterized by the notion of reverse remodeling, which is synonymous with function recovery. It is this process at the level of the right ventricle that is recognized as extremely important for the success of LVAD programs, especially in the group of patients who have a certain degree of right ventricular weakness preoperatively. The basic requirements of the cardiac surgery team are adequate preoperative assessment of right ventricular weakness, then application of measures to prevent damage and load on the right ventricle during and after LVAD implantation, as well as providing adequate therapeutic measures for right ventricular recovery in the postimplantation period.

Risk factors of readmission to acute care hospital among individuals with heart failure and left ventricular assist device (LVAD) at inpatient rehabilitation setting (STROBE compliant article)

In post-acute care hospital setting, the heart failure (HF) individuals with left ventricular assist device (LVAD) have about 30% of transfer to acute care hospitals which requires readmission. There is relative increase in cost and mortality due to the readmission.The goal of this study is to identify possible risk factors at Inpatient Rehabilitation Unit (IRU) to decrease the rate of readmission to acute care hospitals.This study is retrospective study at the Inpatient Rehabilitation Unit (IRU)Twenty one individuals with HF and LVAD were admitted to IRU. We determined 2 subgroups. One is the readmission group (Readmission) and the other is the control group (Control). Readmission (n = 6) is the individuals who were transferred to acute care hospital, and Control (n = 15) is the individuals who were discharged.To compare Readmission group with Control group and evaluate demographic, laboratory, and functional outcome parameters. Main Outcome Measures are Body Mass Index (BMI), International Normalized Ratio (INR), and Functional independence measure (FIM).At admission, INR in Readmission group was 3.4 ± 1.2 and in Control group was 2.2 ± 0.5 with a statistically significant p value (P = .004) and FIM score in Readmission group was 81.2 ± 15.9 and in Control group was 96.3 ± 11.5 with a statistically significant p value (P = .023).The study showed the individuals with HF and LVAD at IRU had high INR and low FIM which may be the cause for readmission and need more attentive care. This data can help identify the factors causing readmission and help reduce the rate of readmission. Further evaluation is necessary to determine the cause for readmission.

HFSA/SAEM/ISHLT clinical expert consensus document on the emergency management of patients with ventricular assist devices

Mechanical circulatory support is now widely accepted as a viable long-term treatment option for patients with end-stage heart failure (HF). As the range of indications for the implantation of ventricular assist devices grows, so does the number of patients living in the community with durable support. Because of their underlying disease and comorbidities, in addition to the presence of mechanical support, these patients are at a high risk for medical urgencies and emergencies (Table 1). Thus, it is the responsibility of clinicians to understand the basics of their emergency care. This consensus document represents a collaborative effort by the Heart Failure Society of America, the Society for Academic Emergency Medicine, and the International Society for Heart and Lung Transplantation (ISHLT) to educate practicing clinicians about the emergency management of patients with ventricular assist devices. The target audience includes HF specialists and emergency medicine physicians, as well as general cardiologists and community-based providers.

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.

The Rehabilitation of Patients With Advanced Heart Failure After Left Ventricular Assist Device Placement: A Narrative Review

Because more patients with advanced heart failure are receiving a left ventricular assist device (LVAD) as destination therapy or a bridge to transplantation, there is increasing attention on functional outcomes and quality of life after LVAD implantation. Rehabilitation providers in the acute inpatient rehabilitation setting increasingly will treat patients with an LVAD and should understand the exercise physiology, medical management, rehabilitation considerations, and outcomes after rehabilitation for patients with an LVAD. The purpose of this article is to provide the physiatrist with a comprehensive understanding of the rehabilitation of patients with advanced heart failure and LVAD implantation. Changes in relevant organ system physiology and exercise physiology after LVAD are summarized. Safety of rehabilitation and program considerations for acute inpatient rehabilitation are reviewed. Recommendations for medical management and prevention of secondary complications seen in patients with an LVAD are outlined. A discussion of outcomes after acute inpatient rehabilitation, the dual diagnosis of stroke and LVAD placement, and long-term cognitive, functional, and quality-of-life outcomes after LVAD placement is presented.

Plasma Levels of MicroRNA-155 Are Upregulated with Long-Term Left Ventricular Assist Device Support

Left ventricular assist device (LVAD) therapy unloads the failing heart but exposes the human body to unique pathophysiologic demands such as continuous blood flow and complete univentricular support, which are associated with increased risk of adverse clinical outcomes. MicroRNAs (miRNAs) are 22-23 nucleotide RNAs involved in regulation of multiple biologic processes including the pathogenesis of heart failure (HF). Thus, measurement of miRNAs may have potential in both diagnostics as circulating biomarkers and in therapeutics for targeted interventions. We examined 23 distinct miRNAs that have previously been shown to play a role in HF pathogenesis and measured them in 40 individuals both before continuous-flow LVAD implantation and at a median of 96.5 days after implantation. Quantitative real-time polymerase chain reaction was performed for miRNA amplification, and 19 miRs were included in statistical analysis. Wilcoxon signed-rank tests were used to compare within-patient median relative quantification values pre- and post-LVAD placement. The median age of patients was 67 years, and 57.5% were at Interagency Registry for Mechanically Assisted Circulatory Support level 1-2. After LVAD support, only miR-155 was found to be statistically significant (p < 0.002), with an upregulation in plasma expression levels with LVAD support, which persisted regardless of the direction of change in serial HF biomarker levels. MicroRNA-155, which has been shown to play a central role in inflammation and neovascularization, was upregulated with long-term LVAD support. If validated by future studies, miR-155 may help further inform on underlying LVAD physiology and has a role as a therapeutic target in this patient population.

Mathematical Modeling of Rotary Blood Pumps in a Pulsatile In Vitro Flow Environment

Nowadays, sacrificing animals to develop medical devices and receive regulatory approval has become more common, which increases ethical concerns. Although in vivo tests are necessary for development and evaluation of new devices, nonetheless, with appropriate in vitro setups and mathematical models, a part of the validation process can be performed using these models to reduce the number of sacrificed animals. The main aim of this study is to present a mathematical model simulating the hydrodynamic function of a rotary blood pump (RBP) in a pulsatile in vitro flow environment. This model relates the pressure head of the RBP to the flow rate, rotational speed, and time derivatives of flow rate and rotational speed. To identify the model parameters, an in vitro setup was constructed consisting of a piston pump, a compliance chamber, a throttle, a buffer reservoir, and the CentriMag RBP. A 40% glycerin-water mixture as a blood analog fluid and deionized water were used in the hydraulic circuit to investigate the effect of viscosity and density of the working fluid on the model parameters. First, model variables were physically measured and digitally acquired. Second, an identification algorithm based on regression analysis was used to derive the model parameters. Third, the completed model was validated with a totally different set of in vitro data. The model is usable for both mathematical simulations of the interaction between the pump and heart and indirect pressure measurement in a clinical context.

Mechanical Circulatory Support: Heart Failure Therapy “in Motion”

Because the first generation of pulsatile-flow devices was primarily used to bridge the sickest patients to transplantation (bridge-to-transplant therapy), the current generation of continuous-flow ventricular assist devices qualifies for destination therapy for patients with advanced heart failure who are ineligible for transplantation. The first-generation devices were associated with frequent adverse events, limited mechanical durability, and patient discomfort due device size. In contrast, second-generation continuous-flow devices are smaller, more quiet, and durable, thus resulting in less complications and significantly improved survival rates. Heart transplantation remains an option for a limited number of patients only, and this fact has also triggered the discussion about the optimal timing for device implantation. The increasing use of continuous-flow devices has resulted in new challenges, such as adverse events during long-term support, and high hospital readmission rates. In addition, there are a number of device-related complications including mechanical problems such as device thrombosis, percutaneous driveline damage, as well as conditions such as hemolysis, infection, and cerebrovascular accidents. This review provides an overview of the evolution of mechanical circulatory support systems from bridge to transplantation to destination therapy including technological advances and clinical improvements in long-term patient survival and quality of life. In addition, recent changes in device implant strategies and current trials are reviewed and discussed. A brief glimpse into the future of mechanical circulatory support therapy will summarize the innovations that may soon enter clinical practice.

Inhaled Nitric Oxide Augments Left Ventricular Assist Device Capacity by Ameliorating Secondary Right Ventricular Failure

Clinical right ventricular (RV) impairment can occur with left ventricular assist device (LVAD) use, thereby compromising the therapeutic effectiveness. The underlying mechanism of this RV failure may be related to induced abnormalities of septal wall motion, RV distension and ischemia, decreased LV filling, and aberrations of LVAD flow. Inhaled nitric oxide (NO), a potent pulmonary vasodilator, may reduce RV afterload, and thereby increase LV filling, LVAD flow, and cardiac output (CO). To investigate the mechanisms associated with LVAD-induced RV dysfunction and its treatment, we created a swine model of hypoxia-induced pulmonary hypertension and acute LVAD-induced RV failure and assessed the physiological effects of NO. Increased LVAD speed resulted in linear increases in LVAD flow until pulse pressure narrowed. Higher speeds induced flow instability, LV collapse, a precipitous fall of both LVAD flow and CO. Nitric oxide (20 ppm) treatment significantly increased the maximal achievable LVAD speed, LVAD flow, CO, and LV diameter. Nitric oxide resulted in decreased pulmonary vascular resistance and RV distension, increased RV ejection, promoted LV filling and improved LVAD performance. Inhaled NO may thus have broad utility for the management of biventricular disease managed by LVAD implantation through the effects of NO on LV and RV wall dynamics.

A Case of Cough-induced Ventricular Tachycardia in a Patient with a Left Ventricular Assist Device

In this case, the patient's ventricular tachycardia (VT) was specifically induced by coughing, which has not previously been described. Decreasing the rotational speed of the left ventricular assist device (LVAD) and increasing preload by stopping the patient's nitrates and reducing diuretic dose allowed improved filling of the left ventricle (LV) and increased LV volumes. When coughing recurred, the effects on the LV cavity were less pronounced and thus VT was reduced. Although ventricular arrhythmias are common after LVAD placement, this is a unique case in which VT was caused by coughing, which is ordinarily not considered arrhythmogenic.

Initial In Vivo Evaluation of a Novel Left Ventricular Assist Device

The aim of the study was to use the ovine model to evaluate the hemocompatibility and end-organ effects of a newly developed magnetic suspension centrifugal left ventricular assist device (LVAD) by CH Biomedical Inc., Jiangsu, China. The LVADs were implanted in 6 healthy sheep, where inflow was inserted into the left ventricular apex and outflow was anastomosed to the descending aorta. All sheep received anticoagulation and antiaggregation therapy during the study. Hematologic and biochemical tests were performed to evaluate anemia, hepatorenal function, and the extent of hemolysis. The experiments lasted for up to 30 days on the beating hearts. All sheep were humanely killed at the termination of the experiments, and the end-organs were examined macroscopically and histopathologically. Autopsy was performed in all animals and there was no thrombus formation observed inside the pump. The pump's inflow and outflow conduits were also free of thrombus. Hematologic and biochemical test results were within normal limits during the study period. Postmortem examination of the explanted organs revealed no evidence of ischemia or infarction. Based on the in vivo study, this LVAD is suitable for implantation and can provide efficient support with good biocompatibility. The encouraging results in this study suggest that it is feasible to evaluate the device's long-term durability and stability.

Biomechanics of Cardiac Function

The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.

Left ventricular assist devices: a kidney's perspective

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

Devices in heart failure--the new revolution

Heart failure is a growing epidemic, with more patients living longer and suffering from this disease. There is a growing segment of patients who have persistent symptoms despite pharmacologic therapy. In an era when transplants are rare, the need for devices and interventions that can assist ventricular function is paramount. This review goes through the devices used in heart failure, including left ventricular reconstruction, aortic counterpulsation, short-term mechanical circulatory support, long-term mechanical circulatory support, and right heart interventions.

Investigation of hemodynamics in an in vitro system simulating left ventricular support through the right subclavian artery using 4-dimensional flow magnetic resonance imaging

OBJECTIVES

Left ventricular assist devices are an important treatment option for patients with heart failure alter the hemodynamics in the heart and great vessels. Because in vivo magnetic resonance studies of patients with ventricular assist devices are not possible, in vitro models represent an important tool to investigate flow alterations caused by these systems. By using an in vitro magnetic resonance-compatible model that mimics physiologic conditions as close as possible, this work investigated the flow characteristics using 4-dimensional flow-sensitive magnetic resonance imaging of a left ventricular assist device with outflow via the right subclavian artery as commonly used in cardiothoracic surgery in the recent past.

METHODS

An in vitro model was developed consisting of an aorta with its supra-aortic branches connected to a left ventricular assist device simulating the pulsatile flow of the native failing heart. A second left ventricular assist device supplied the aorta with continuous flow via the right subclavian artery. Four-dimensional flow-sensitive magnetic resonance imaging was performed for different flow rates of the left ventricular assist device simulating the native heart and the left ventricular assist device providing the continuous flow. Flow characteristics were qualitatively and quantitatively evaluated in the entire vessel system.

RESULTS

Flow characteristics inside the aorta and its upper branching vessels revealed that the right subclavian artery and the right carotid artery were solely supported by the continuous-flow left ventricular assist device for all flow rates. The flow rates in the brain-supplying arteries are only marginally affected by different operating conditions. The qualitative analysis revealed only minor effects on the flow characteristics, such as weakly pronounced vortex flow caused by the retrograde flow via the brachiocephalic artery.

CONCLUSIONS

The results indicate that, despite the massive alterations in natural hemodynamics due to the retrograde flow via the right subclavian and brachiocephalic arteries, there are no drastic consequences on the flow in the brain-feeding arteries and the flow characteristics in the ascending and descending aortas. It may be beneficial to adjust the operating condition of the left ventricular assist device to the residual function of the failing heart.

Can Intraoperative Transesophageal Echocardiography Predict Postoperative Aortic Insufficiency in Patients Receiving Implantable Left Ventricular Assist Devices?

OBJECTIVE

Aortic insufficiency (AI) develops in 25% of patients after left ventricular assist device (LVAD) insertion. The objective of this study was to evaluate the occurrence of new-onset AI upon initiation of cardiopulmonary bypass (CPB) required for LVAD insertion and the potential ability of this new-onset AI to predict development of post-LVAD insertion AI.

DESIGN

Forty-one patients undergoing LVAD insertion were studied. Intraoperative transesophageal echocardiography (TEE) evaluation was performed at baseline (post-induction, pre-sternotomy), 5 minutes after CPB initiation, and post-chest closure. Patients were followed up postoperatively for development of AI.

SETTING

Single university hospital.

PARTICIPANTS

Patients undergoing elective LVAD insertion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

At baseline, 35 patients exhibited none-trace AI, 4 exhibited mild AI, 2 exhibited moderate AI, and none exhibited severe AI. After initiation of CPB, 34 patients exhibited no change in degree of AI yet 7 exhibited an increase in AI severity. However, all 7 patients exhibited no change in degree of AI at chest closure and one exhibited a decrease in AI severity. Four patients developed at least moderate AI during the postoperative period (range 3-8 months). However, only one of these patients exhibited an increase in AI severity after initiation of CPB for LVAD insertion. No significant changes in aortic root measurements were observed during the entire intraoperative period (within patients nor between patients with/without development of at least moderate postoperative AI).

CONCLUSIONS

One in 5 patients undergoing LVAD insertion will demonstrate an increase in AI severity at CPB initiation without changes in aortic root measurements. None of the information obtained from intraoperative TEE seemed to predict development of at least moderate postoperative AI.

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

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

An insight into short- and long-term mechanical circulatory support systems

Cardiogenic shock due to acute myocardial infarction, postcardiotomy syndrome following cardiac surgery, or manifestation of heart failure remains a clinical challenge with high mortality rates, despite ongoing advances in surgical techniques, widespread use of primary percutaneous interventions, and medical treatment. Clinicians have, therefore, turned to mechanical means of circulatory support. At present, a broad range of devices are available, which may be extracorporeal, implantable, or percutaneous; temporary or long term. Although counter pulsation provided by intra-aortic balloon pump (IABP) and comprehensive mechanical support for both the systemic and the pulmonary circulation through extracorporeal membrane oxygenation (ECMO) remain a major tool of acute care in patients with cardiogenic shock, both before and after surgical or percutaneous intervention, the development of devices such as the Impella or the Tandemheart allows less invasive forms of temporary support. On the other hand, concerning mid-, or long-term support, left ventricular assist devices have evolved from a last resort life-saving therapy to a well-established viable alternative for thousands of heart failure patients caused by the shortage of donor organs available for transplantation. The optimal selection of the assist device is based on the initial consideration according to hemodynamic situation, comorbidities, intended time of use and therapeutic options. The present article offers an update on currently available mechanical circulatory support systems (MCSS) for short and long-term use as well as an insight into future perspectives.

Physical therapist management of patients with ventricular assist devices: key considerations for the acute care physical therapist

This article provides an overview of the utilization of ventricular assist devices (VADs), reviews the common features of VADs and management of VAD recipients, discusses clinical considerations in the rehabilitation process, and describes the role of the acute care physical therapist in the care of VAD recipients. With more than 5 million people in the United States with heart failure, and with a limited ability to manage the progressive and debilitating nature of heart failure, VADs are becoming more commonplace. In order to prescribe a comprehensive and effective plan of care, the physical therapist needs to understand the type and function of the VADs and the goals of the VAD program. The goals for the physical therapist are: (1) to deliver comprehensive rehabilitation services to patients on VAD support, (2) to develop an understanding of the role of functional mobility in recovery, and (3) to understand how preoperative physical function may contribute to the VAD selection process. The acute care physical therapist has an increasing role in providing a complex range of rehabilitation services, as well as serving as a well-educated resource to physical therapists across the health care spectrum, as more VAD recipients are living in the community.

Pulsatile vs. continuous flow in ventricular assist device therapy

A left ventricular assist device (LVAD) is an important treatment option for a patient with end-stage heart failure. Both continuous and non-pulsatile devices are available, each with different effects on a patient's physiology. In general, these effects are not clinically significant with the exception of bleeding events which are more common with continuous-flow devices in some series. Both devices increase survival beyond medical management. Continuous-flow devices are smaller and are associated with less overall morbidity than pulsatile devices.

Prehospital assessment and management of patients with ventricular-assist devices

Advances in the management of heart failure have led to an increasing number of patients living outside the hospital with a variety of ventricular-assist devices (VADs). These implantable pumps may be placed temporarily as a bridge to cardiac transplantation or resolution of a reversible condition, or as destination therapy for the rest of the patient's life. Emergency medical services (EMS) providers may be called to care for such patients experiencing an emergency related to the device itself, the underlying cardiac condition, or a totally unrelated medical or traumatic issue. Providers should have a basic knowledge of how these devices work and what sort of complications VAD patients may experience. In addition, they should know how to troubleshoot the devices if they alarm or malfunction, what emergency interventions can and cannot be performed, and where to turn for guidance if needed. Challenges related to management of patients with VADs include their poor baseline medical status, limitations of traditional prehospital assessment techniques, the relative infrequency with which these patients are encountered, and the rapidity with which device technology is evolving. This article presents a brief history of VADs, with an emphasis on left ventricular-assist devices (LVADs), reviews the relevant anatomy and pathophysiology, and describes the types of devices currently in clinical use. It discusses patient-specific and device-specific complications that may be encountered and concludes with an approach to prehospital patient assessment and care.

Devices in the management of advanced, chronic heart failure

Heart failure (HF) is a global phenomenon, and the overall incidence and prevalence of the condition are steadily increasing. Medical therapies have proven efficacious, but only a small number of pharmacological options are in development. When patients cease to respond adequately to optimal medical therapy, cardiac resynchronization therapy has been shown to improve symptoms, reduce hospitalizations, promote reverse remodelling, and decrease mortality. However, challenges remain in identifying the ideal recipients for this therapy. The field of mechanical circulatory support has seen immense growth since the early 2000s, and left ventricular assist devices (LVADs) have transitioned over the past decade from large, pulsatile devices to smaller, more-compact, continuous-flow devices. Infections and haematological issues are still important areas that need to be addressed. Whereas LVADs were once approved only for 'bridge to transplantation', these devices are now used as destination therapy for critically ill patients with HF, allowing these individuals to return to the community. A host of novel strategies, including cardiac contractility modulation, implantable haemodynamic-monitoring devices, and phrenic and vagus nerve stimulation, are under investigation and might have an impact on the future care of patients with chronic HF.

Significance of postoperative acute renal failure after continuous-flow left ventricular assist device implantation

BACKGROUND

Deteriorating renal function is common in patients with advanced heart failure and is associated with poor outcomes. The relationship between renal function and left ventricular assist device (LVAD) implantation is complex and has been explored in multiple studies with contradictory results. The aim of our study is to examine the significance of postoperative renal failure after implantation of a continuous-flow LVAD and its relationship to outcomes.

METHODS

From March 2006 to July 2011, 100 patients underwent implantation of a HeartMate II (Thoratec Corp, Pleasanton, CA) or HeartWare (Heart International, Inc, Framingham, MA) LVAD at our institution. Patients were stratified based on postoperative development of acute renal failure (ARF). Variables were compared using 2-sided t tests, χ(2) tests, Cox proportional hazards models, and log-rank tests to determine whether there was a difference between the 2 groups and whether postoperative renal failure was a significant independent predictor of outcome.

RESULTS

We identified 28 patients (28%) with postoperative ARF and 72 patients (72%) without postoperative ARF. The 2 groups were similar with regard to demographics and comorbidities. The patients with ARF were more likely to be intubated preoperatively (14.3% versus 1.4%; p = 0.021) and had higher preoperative central venous pressure (CVP) (14.3 mm Hg versus 10.7 mm Hg; p = 0.015). Postoperatively patients with ARF had a longer hospital stay (32.4 versus 18.7; p = 0.05), were more likely to experience right ventricular (RV) failure (25% versus 5.6%; p = 0.01) and ventilator-dependent respiratory failure (VDRF) (28.6% versus 6.9%; p = 0.007). There was a significant difference when comparing the ARF and non-ARF groups for 30-day (17.9% versus 0%; p < 0.001), 180-day (28.6% versus 2.8%; p < 0.001), and 360-day mortality (28.6% versus 6.9%; p = 0.012).

CONCLUSIONS

Patients in whom ARF developed after LVAD implantation had a higher rate of VDRF and RV failure and a longer length of stay (LOS). Postoperative ARF was associated with higher mortality at the 30-day, 180-day, and 360-day intervals. ARF after LVAD may be an early marker of poor outcome, particularly RV failure, and may be an opportunity for early intervention and rescue.

Management of intracranial hemorrhage in a child with a left ventricular assist device

Pediatric patients bridged to heart transplant with LVADs require chronic anticoagulation and are at increased risk of hemorrhagic complications, including intracranial hemorrhage. In this population, intracranial hemorrhage is often fatal. We report a case of successful management of a five-yr-old-boy with DCM on an LVAD who developed a subdural hematoma. We initially chose medical management, weighing the patient's high risk of thromboembolism from anticoagulation reversal against the risk of his chronic subdural hematoma. When head CT showed expansion of the hemorrhage with increasing midline shift, we chose prompt surgical evacuation of the hematoma with partial reversal of anticoagulation, given the increased risk of acute deterioration. The patient ultimately received an orthotopic heart transplant and was discharged with no permanent neurological complications. This represents a case of a pediatric patient on an LVAD who survived a potentially fatal subdural hematoma and was successfully bridged to cardiac transplantation.

Evaluation of GI bleeding after implantation of left ventricular assist device

BACKGROUND

Left ventricular assist devices (LVADs) have revolutionized the management of end-stage heart failure (ESHF). However, unexpectedly high rates of GI bleeding (GIB) have been described, and etiology and outcome remain unclear.

OBJECTIVE

To determine the prevalence, etiology, and outcome of GIB in LVAD recipients.

DESIGN

Retrospective case series.

SETTING

Tertiary care academic university hospital.

PATIENTS

154 ESHF patients (55.4 years, 122 men/32 women) with LVADs implanted over a 10-year period.

MAIN OUTCOME MEASUREMENTS

Overt or occult GIB prompting endoscopic evaluation ≥ 7 days after LVAD implantation.

RESULTS

Over a mean of 0.9 ± 0.1 years of follow-up, 29 patients (19%) experienced 44 GIB episodes. Patients with GIB were older and received anticoagulation therapy before devices were implanted (P ≤ .02 for each). GIB was overt (n = 31) rather than occult (n = 13), and most patients presented with melena (n = 22, 50%); hemodynamic instability was observed in 13.6%. Each bleeding episode required 2.1 ± 0.1 diagnostic or therapeutic procedures, and a source was localized in 71%. Upper endoscopy provided the highest diagnostic yield; peptic bleeding (n = 14) and vascular malformations (n = 8) dominated the findings. Endoscopy was safe and well tolerated. Overall mortality was 35%, none directly from GIB.

LIMITATION

Retrospective design.

CONCLUSIONS

Rates of GIB with LVADs are higher than that seen in other patient populations, including those receiving anticoagulation and antiplatelet therapy. GIB episodes are mostly overt and predominantly from the upper GI tract. Endoscopy is safe in the LVAD population.

Risk factors for early death in patients bridged to transplant with continuous-flow left ventricular assist devices

BACKGROUND

Recent evidence suggests patients bridged to heart transplant (BTT) have equivalent outcomes as those undergoing conventional orthotopic heart transplantation (OHT). However, data on risk factors for early death in BTT patients are limited.

METHODS

We retrospectively reviewed the United Network for Organ Sharing database of all patients bridged to OHT with a HeartMate II from January 2005 to December 2010. The primary outcome was all-cause 90-day mortality. Additional postoperative outcomes were cerebrovascular accident and need for renal replacement therapy. Kaplan-Meier analysis assessed survival. Preoperative variables associated with 90-day death on univariate analysis (p<0.2) were included in a multivariable Cox proportional hazards regression.

RESULTS

A HeartMate II was used to bridge 1,312 patients (average age, 52±12 years) to OHT, most commonly for idiopathic cardiomyopathy (50.7%). During the study, 171 patients (13.0%) died. The unadjusted 90-day survival was 92.3%. The highest annual average center volume in this cohort, examining for BTT recipients only, was 28 BTT procedures yearly. Postoperative cerebrovascular accident occurred in 29 patients (2.2%), and 106 (8.3%) required renal replacement therapy. Cox regression revealed age, glomerular filtration rate, African American race, human leukocyte antigen mismatch, serum bilirubin, need for mechanical ventilation, donor age, and prolonged ischemia time were associated with 90-day death. Early survival was improved for patients who underwent OHT at high-volume centers (p=0.01).

CONCLUSIONS

This study examining risk factors for early death in patients bridged to OHT using HeartMate II mechanical assistance will aid in identifying patients best suited to benefit from this technology.

Regenerating functional heart tissue for myocardial repair

Heart disease is one of the leading causes of death worldwide and the number of patients with the disease is likely to grow with the continual decline in health for most of the developed world. Heart transplantation is one of the only treatment options for heart failure due to an acute myocardial infarction, but limited donor supply and organ rejection limit its widespread use. Cellular cardiomyoplasty, or cellular implantation, combined with various tissue-engineering methods aims to regenerate functional heart tissue. This review highlights the numerous cell sources that have been used to regenerate the heart as well as cover the wide range of tissue-engineering strategies that have been devised to optimize the delivery of these cells. It will probably be a long time before an effective regenerative therapy can make a serious impact at the bedside.

Being a close relative of a patient with a left ventricular assist device

BACKGROUND

Every year in Sweden, between five and ten patients receive a mechanical heart pump due to grave heart failure. One such pump is the left ventricle assist device (LVAD). At home they need much support from their family.

AIM

To investigate the close relatives' experience of their role in relation to patients with an LVAD.

METHODS

An exploratory study using unstructured interviews with six close relatives of patients with an LVAD. The interviews consisted of one open question: 'What is it like to be the close relative of a patient with an LVAD?' The interviews were analysed using thematic content analysis.

RESULTS

The time before LVAD surgery was described as a time of emotional ups and downs, and compared to 'being on an emotional rollercoaster ride'. The nearest relatives were in shock, felt anxiety and uncertainty, and wished to be near the patient. The time after surgery was described as a period in which they had to 'cope with the new situation.' During this period, the staff was experienced as a resource and the relatives described feelings of gratitude, willpower, and acceptance. The stay at home with a person with an LVAD was described as a 'new orientation phase' with limited freedom and the need for respite care. The interviewees expressed the need for support, especially once the patient was at home.

CONCLUSION

It is important to also offer long-term professional support to the nearest relatives of patients with an LVAD.

Wave intensity analysis of para-aortic counterpulsation

Wave intensity analysis (WIA) was used to delineate and maximize the efficacy of a newly developed para-aortic blood pump (PABP). The intra-aortic balloon pump (IABP) was employed as the comparison benchmark. Acute porcine experiments using eight pigs, randomly divided into IABP (n = 4) and PABP (n = 4) groups, were conducted to compare the characteristics of intra- and para-aortic counterpulsation. We measured pressure and velocity with probes installed in the left anterior descending coronary artery and aorta, during and without PABP assistance. Wave intensity for aortic and left coronary waves were derived from pressure and flow measurements with synchronization correction applied. To achieve maximized support efficacy, deflation timings ranging from 25 ms ahead of to 35 ms after the R-wave were tested. Similar to those associated with IABP counterpulsation, the PABP-generated backward-traveling waves predominantly drove aortic and coronary blood flows. However, in contrast with IABP counterpulsation, the nonocclusive nature of the PABP allowed systolic unloading to be delayed into early systole, which resulted in near elimination of coronary blood steal without diminution of systolic left ventricular ejection wave intensities. WIA can elucidate subtleties among different counterpulsatile support means with high sensitivity. Total accelerating wave intensity (TAWI), which was defined as the sum of the time integration of accelerated parts of the positive and negative wave intensities, was used to quantify counterpulsation efficacy. In general, the larger the TAWI gain, the better the counter-pulsatile support efficacy. However, when PABP deflation timings were delayed to after the R-wave, the TAWI was found to be inversely correlated with coronary perfusion. In this delayed deflation timing setting, greater wave cancellation occurred, which led to decreased TAWI but increased coronary perfusion attributed to blood regurgitation reduction.

Preliminary in vivo testing of a novel pump for short-term extracorporeal life support

BACKGROUND

Blood pumps used for temporary circulatory support have limitations. We propose a novel device designed for short-term extracorporeal support that is intrinsically volume responsive, afterload insensitive, and incapable of cavitation or excessive hemolysis. After in vitro testing, we performed the initial in vivo implantations and assessments.

METHODS

The BioVAD prototype (MC3, Inc, Ann Arbor, MI) was implanted in 6 adult male sheep (60.2±2.8 kg) through the left ventricular apex and descending thoracic aorta. Arterial, left and right atrial, and pump inlet and outlet pressures and BioVAD flow were measured and recorded. The animals were volume loaded to assess volume responsiveness, and the inlet lines were abruptly clamped during maximum support to observe for cavitation. An acute heart failure model was created with rapid ventricular pacing, and the animals were supported for 4 hours.

RESULTS

Peak flow was 3.19±0.56 L/min and increased to 3.71±0.53 L/min with 20 mm Hg vacuum-assisted drainage. Without manual changes in pump settings, pump flow increased 17.5% with volume loading. During acute venous line occlusion, there was no evidence of cavitation, and inlet suction was minimal. Hemodynamics were maintained for 4 hours during acute heart failure.

CONCLUSIONS

The BioVAD provided adequate flow in an acute in vivo model. Its design may be superior for short-term extracorporeal support.