Mechanical Circulatory Support for Advanced Heart Failure

Both acute and chronic systolic heart failure can progress to an advanced phase, resulting in stage D heart failure and even cardiogenic shock. Despite significant progress in the treatment of systolic heart failure using medical and device therapies, this terminal phase continues to be prevalent and associated with unacceptably high morbidity and mortality. Given the inability to offer cardiac transplantation to the majority of those presenting with advanced heart failure, alternative strategies for cardiac replacement therapy are often required. Although there has been interest in using mechanical devices to support the circulation since the advent of cardiopulmonary bypass, it is only in the past 20 years that ventricular assist devices (VAD) have become viable options for therapy. Indeed, we are now entering an era where circulatory assist devices are being used not only to temporarily support patients with post-cardiotomy shock, but also as a long-term treatment in ambulatory heart failure patients. Furthermore, we are now able to utilize data from multicenter trials and registries to guide treatment decisions. These data have clearly shown that VADs improve survival and quality of life in patients with advanced heart failure when implanted as a temporary measure (bridge to recovery and bridge to transplant) or as long-term support (destination therapy). However, with a growing heart failure population there is much work to be done to improve VAD technology, patient selection, post-implantation management, and to define the optimal role for assist devices in the management of systolic heart failure. We are also in the nascent stages of fully understanding the impact of mechanical support on the failing myocardium, and developing research methodologies to study novel therapies in tandem with VADs to facilitate ventricular recovery. These important questions are currently being addressed in ongoing clinical trials, registry analyses, and translational research endeavors.     

Endocardial catheter ablation of ventricular tachycardia in patients with ventricular assist devices

BACKGROUND: The outcomes of patients with ventricular assist devices (VADs) who undergo catheter ablation for ventricular tachycardia (VT) have not been reported. OBJECTIVE: The purpose of this study was to assess the feasibility, safety, and efficacy of endocardial VT ablation in patients with VADs. METHODS: We retrospectively reviewed three cases at our institution where endocardial catheter ablation was performed in patients with VADs and incessant VT. RESULTS: Three patients with underlying cardiomyopathies and VADs underwent VT ablation for incessant VT refractory to multiple antiarrhythmic medications. In each case, VT was either eliminated or significantly ameliorated by catheter ablation. No procedure-related complications occurred. The hemodynamic stability afforded by the VAD played an important role in facilitating ablation in two of the cases. CONCLUSION: Catheter ablation for VT in VAD patients appears to be feasible, safe, and effective based on our initial experience. Several technical issues, such as decreases in ventricular volumes that can limit maneuverability of the ablation catheter and potential entrapment of the mapping catheter in the inflow cannula, need to be considered at the time of ablation.     

Durable mechanical circulatory support devices

Individuals afflicted with advanced systolic heart failure who have become unresponsive to standard medical and electrical therapies are categorized as having American Heart Association stage D heart failure. The high mortality rates for medically treated stage D heart failure have not improved in the last 10 years, and patients at this advanced stage require either palliative measures or surgical management of heart failure. In recent years, surgically implanted ventricular assist devices (VADs) have become available for long-term use and are now commonly used as a therapy for advanced heart failure. The data generated from this early experience have clearly shown that VADs improve survival and quality of life in patients with advanced heart failure when implanted as a temporary measure or as long-term support. However, with a growing heart failure population, there is much work to be done to continually improve VAD technology, patient selection criteria, and postimplantation management to define the optimal role for assist devices in the management of systolic heart failure.     

Ventricular assist devices: initial orientation

Ventricular assist device (VAD) technology has come from large pulsatile-flow devices with a high rate of technical malfunctions to small continuous flow (cf) devices. Mechanical circulatory support (MCS) systems may be used as short-, mid- or long-term support. Especially if mid- or long-term support is anticipated left VADs (LVADs) have been reported with excellent one and two year survival rates and improved quality of life (QoL). Timing of implantation, patient selection, assessing function of the right ventricular and surgical considerations regarding surgical access side, valve pathology and exit side of the percutaneous lead remain crucial issues for the outcome. In contrast VADs designed for children especially for all age groups, are still underrepresented but increased experience with existing pediatric VADs as well as introduction of second and third generation VADs into in the pediatric age group, offer new perspectives.KEY WORDS : Ventricular assist device (VAD), mechanical circulatory support (MCS), quality of life (QoL)     

Left Ventricular Assist Devices and Other Devices for End-Stage Heart Failure: Utility of Echocardiography

The burgeoning ranks of patients with heart failure, the limited number of organs available for heart transplant, and technological improvements have made ventricular assist devices (VADs) important therapeutic options for patients with acute and chronic cardiac decompensation. The increased use of VADs is paralleled by an increased use of transthoracic and transesophageal echocardiography to 1) assist in the selection of patients for VAD therapy and VADs to meet patient needs; 2) identify important anatomic considerations prior to implant; 3) guide placement of VADs; 4) diagnose the etiology of VAD dysfunction; and 5) guide the weaning from VAD support and the optimization of VAD device settings. This review discusses types of VADs and the uses of echocardiography in the care of VAD patients.     

Severe hemolysis associated with use of the impella LP 2.5 mechanical assist device

The Impella LP 2.5 is a percutaneously implantable axial flow device designed to offer circulatory support for patients in cardiogenic shock during percutaneous coronary interventions (PCI). While most axial flow devices are associated with hemolysis, clinically relevant hemolysis with this device has not been reported. We report a case of a 66‐year‐old woman with hemodynamic collapse during an elective PCI who was successfully resuscitated with an Impella device. She developed marked biochemical evidence of intravascular hemolysis. This necessitated device removal which resulted in prompt resolution of the hemolysis. We advise routine measurement of biochemical markers of hemolysis and serial hemoglobin values during Impella device support to allow timely detection and treatment of this important complication. © 2012 Wiley Periodicals, Inc.     

Anticoagulation management in mechanical circulatory support

Heart failure continues to be a worldwide epidemic, effecting over 23 million persons. Despite advances in medical therapy, the disease is progressive and a significant proportion of patients will need advanced heart replacement therapy. Continuous flow assist devices have become a standard approach for many patients both as a bridge to cardiac transplantation and as destination therapy (DT). However, device related complications such as bleeding and thrombosis continue to hinder further advancements of this technology. The field is rapidly advancing and efforts to reduce pump complications are directed towards improving hemocompatibility and maximizing blood flow without clinically significant hemolysis, areas of stasis or turbulent flow.     

Mechanical Circulatory Support��Results, Developments and Trends

The implantation of ventricular assist devices (VADs) is a valuable option in patients with end-stage heart failure. The number of VAD implantations is growing worldwide. Between July 1987 and July 2010, we implanted 1,598 VADs in 1,455 patients. The majority were male (81.0%), and their mean age was 49.4 years (range 0.3–82 years). Indications for implantation were: cardiomyopathy (n = 1,074), post-cardiotomy heart failure (n = 282), acute myocardial infarction (n = 83), graft failure after heart transplantation (n = 64), and others (n = 61). In 55.5%, the VAD implanted was left ventricular, in 39.5% biventricular, and in 4.8% right ventricular. Until 1995, the implanted pumps were mostly pulsatile. Today, however, more than 95% of the implanted VADs are continuous-flow rotary pumps. The average support time was 148.6 days (range 0–1,836 days). The percentage of biventricular VADs has dropped over the years to 20% in 2009. Three hundred forty-seven patients could be successfully bridged to heart transplantation. In 122 patients (8.3%), the device could be explanted after myocardial recovery. In 2009, 31.4% of the patients were implanted for permanent support. During the study period, 521 patients could be discharged home or to a rehabilitation center. Implantation of ventricular assist devices is now an established treatment for patients with both acute and chronic end-stage heart failure. Small implantable left ventricular assist devices of the second and third generation are now broadly employed worldwide, with growing acceptance and decreasing complications. The percentage of biventricular support has dropped over the years to 20%.     

Evaluation of Cardiac Recovery in Ventricular Assist Device Recipients: Particularities,Reliability, and Practical Challenges

In carefully selected patients with ventricular assist devices (VADs), good long-term results after device weaning and explantation can be achieved when reverse remodelling and improvement of native cardiac function occur. Monitoring of cardiac size, geometry, and function after initial VAD implantation is necessary to identify such patients. Formal guidelines for recovery assessment in patients with VADs do not exist, and protocols for recovery assessment and criteria for device weaning and explantation vary among centres. Barriers to evaluation of cardiac recovery include technical problems in obtaining echo images in patients with VADs, time restrictions for necessary VAD reductions/interruptions during assessment, and regurgitant flow patterns that occur with interruption of continuous flow VADs. The few larger studies addressing cardiac recovery after VAD implantation employed varied study designs, limiting interpretation. Current clinical practice is guided largely by local practice patterns, case reports, and small case series, and the available body of research—consisting mostly of expert opinions—has not been systematically addressed. This summary reviews evidence and expert opinion on VAD-promoted cardiac recovery assessment, its reliability, and associated challenges.     

Transcatheter closure of perimembranous ventricular septal defects using umbrella devices.

There is only limited experience of interventional closure of perimembranous ventricular septal defects (pmVSDs), particularly on the long-term follow-up. This is a report on our long-term results after transcatheter closure of pmVSDs using the Cardioseal, Starflex, or Rashkind devices. PATIENTS: Between 1993 and 2005, we performed interventional occlusions of pmVSDs in 18 patients. The size of the defect ranged between 4 and 8.5 mm, Q(p)/Q(s) was calculated between 1.3 and 2.2. Except for two, the patients had no other structural heart defect. In the early days, we used the Rashkind PDA occluder (17 mm) in seven, followed by the Cardioseal device (17 mm) in nine, and the 23 mm Starflex device in two patients. RESULTS: Interventional closure of the defects was performed successfully in all patients without any complication during the procedure. Fluoroscopy times were 11.8-53.7 min (median 28.65 min). We achieved a complete closure in 13 patients, three patients with recently implanted devices still show minimal shunting. In two patients the occluder had to be removed surgically because of embolization into the pulmonary artery and significant residual shunting resulting in severe hemolysis in the second patient. In long- (mean 10.7 years) and short-term (mean 0.85 years) follow-up we have not observed any hemolysis, arrhythmias, device dislocations, or device-related aortic or tricuspid regurgitation. CONCLUSION: Transcatheter closure of small pmVSDs using non-selfcentering devices can be performed successfully. Long-term follow-up investigations show encouraging results. Complications like device-embolization and significant residual shunting occur in the presence of large defects and/or concomitant malformations.     

Transcatheter umbrella closure of valvular and paravalvular leaks.

OBJECTIVES. Our aim was to adapt the technique of transcatheter umbrella closure of intracardiac defects for closure of valvular and paravalvular defects. BACKGROUND. The double-umbrella device developed by Rashkind and Cuaso has been safely and effectively delivered across a host of intracardiac defects, but transcatheter closure of valvular and paravalvular leaks has not been reported. METHODS. Between February 1987 and September 1990, eight patients who were believed to be poor operative candidates were taken to the catheterization laboratory for transcatheter double-umbrella closure of a valvular or a paravalvular leak. Four patients had a paravalvular leak around a prosthetic aortic valve. The other four patients had a valvular leak: one patient with a regurgitant native aortic valve after a Stansel procedure and three patients with a regurgitant porcine valve in a left ventricular apex to descending aorta conduit. RESULTS. Placement of a double-umbrella device was attempted in seven of the eight patients and was successful in all seven. Device placement was not attempted in one patient because of the crescentic shape of his defect. Two patients required two devices for each closure; the other five required only one device each. Angiography, performed on six patients after device closure, demonstrated that three patients had a completely occluded defect, two had trivial residual flow and one patient had mild residual flow through the device. All significant complications occurred in one patient who had hemolysis and oliguria that resolved when the initial umbrella was replaced by a larger device. In addition, two devices migrated to the patient's pulmonary arteries but were retrieved in the catheterization laboratory without difficulty. No other early or late complications occurred in 21 to 50 months of follow-up. Of the four patients with a paravalvular leak, the one who did not receive a device died at operation, one patient died at operation for an associated defect (in the operating room the umbrella was found securely in place across the paraaortic defect) and two patients are clinically well at home after 21 and 32 months, respectively. Of the four patients with closure of a valvular leak, one patient remains well at home 50 months later, one patient died at operation for associated defects and two patients had additional successful surgical treatment and remain well 29 months after device placement. CONCLUSIONS. Transcatheter umbrella closure appears to be a reasonable alternative for closure of a valvular or paravalvular leak in patients who are poor operative candidates.     

NHLBI's program for VAD therapy for moderately advanced heart failure: the REVIVE-IT pilot trial

BackgroundVentricular assist devices (VADs) are used to bridge heart failure patients to transplantation, to allow their own hearts to recover, or as permanent (“destination”) therapy. To date, the use of VADs has been limited to late-stage heart failure patients because of the associated device risks. In 2008, a National Heart, Lung, and Blood Institute (NHLBI) working group met to evaluate the treatment of heart failure using VADs and to advise the institute on how therapy for heart failure may be best advanced by clinical trials involving the devices.Methods and ResultsRecognizing the improvements in VAD technology and in patient care and selection over the past decade, the working group recommended that a trial be performed to assess the use of chronic VAD therapy in patients who are less ill than those currently eligible for destination therapy. The hypothesis proposed for the trial is that VAD therapy may improve both survival and quality of life in moderately advanced heart failure patients who are neither inotrope-dependent nor exercise-intolerant and have not yet developed serious consequences such as malnourishment, end-organ damage, and immobility.ConclusionBased on the group’s recommendations, NHLBI issued an RFP in 2009 for the REVIVE-IT Pilot Trail, which will serve to test the hypothesis and inform the pivotal trial.     

Transesophageal Echocardiographic Evaluation of Patients Receiving Mechanical Assistance from Ventricular Assist Devices

Ventricular assist devices (VADs) have been successfully used to provide circulatory support for patients with cardiogenic shock after cardiac surgery. Transesophageal echocardiography plays a vital role in the evaluation of patients on VAD support: it is used to verify the correct positioning of the VAD hardware; to diagnose complications, including intracardiac thrombus and tamponade; and to assess right and left ventricular function when VAD flow is decreased to determine the correct timing for weaning from the device. Future developments may allow us to prospectively identify patients with stunned but viable myocardium who would benefit the most from VAD support.     

Infections associated with ventricular assist devices: epidemiology and effect on prognosis after transplantation

BACKGROUND: Ventricular assist devices (VADs) can be used as a bridge to orthotopic heart transplantation (OHT) in people with severe congestive heart failure. Although they can be inserted for an indefinite time period (unlike balloon pumps), they do carry a substantial risk of infection. We studied the epidemiology, microbiology, and consequences of infection in patients with VADs who ultimately had cardiac transplantation. METHODS: Records of VAD-supported patients at our institution between January 1995 and January 2005 were identified by ICD-9 code. Infection was classified as driveline infection, pocket infection, mediastinitis, or VAD endocarditis in increasing severity of illness. RESULTS: Of 73 patients identified by ICD-9 code, 60 had charts available for review. Of these 60, 72% had a VAD infection: 13 had VAD endocarditis; 3, mediastinitis; 25, pocket infection; and 29, driveline infection. The only association of infection (43 patients, 72%) and demography or underlying disease was that of endocarditis with older age (median age 59 vs. 53 years; P=0.02) and diabetes mellitus (13 patients, 30%; risk ratio 3.4; P=0.01). The duration of VAD support was longer in infected patients (median 125 days) vs. uninfected ones (25 days). Median survival measured from the time of VAD placement (although also true from the time of transplantation) was shorter in patients with VAD endocarditis (120 days) and pocket infection (350 days) vs. no infection (>2400 days) with a significant P=0.017 for endocarditis. Four patients had infections after transplantation that were caused by the same organism as their VAD infection. The predominant pathogens in VAD infection were Staphylococcus and Enterococcus spp. CONCLUSION: VAD use as a bridge to cardiac transplantation is associated with a large number of device-related infections. Patients with infected VADs, on average, wait longer for transplantation than patients with uninfected VADs, and patients with VAD endocarditis have a shorter survival than patients with no VAD infection or simple driveline infection.     

Ventricular Assist Device Use in Patients With Single-Ventricle Circulation

Ventricular assist devices (VADs) are being increasingly used to support patients with congenital heart disease and single-ventricle physiology. Because of their unique anatomy and physiology, special consideration must be used to provide effective mechanical circulatory support for each individual patient. This can include alternative cannulation techniques, strategies to balance cardiac output to the systemic and pulmonary circulations from a single ventricle, or the use of continuous vs pulsatile VADs for better ventricular offloading. In this article we review the etiology of single-ventricle failure, VAD options for support, cannulation strategies, post-VAD management considerations, and outcomes at each of the 3 stages of palliation.     

In Vitro Benchmarking Study of Ventricular Assist Devices in Current Clinical Use

BackgroundLeft ventricular assist devices (LVADs) offer live-saving therapy to transplant-ineligible heart failure patients. A major limitation of the technology includes pump thrombosis, bleeding, and recurrent infection that prove difficult to predict from in vivo animal testing. Shear stress introduced by the LVAD affects more than just hemolysis because platelets, leukocytes, and plasma proteins all contribute to the propensity for complications. It is important to assess overall damage by a new device against a baseline as early as possible in the development process so that design iterations can be made if required.MethodsExplanted VADs currently in clinical use (HeartMate 2 and HVAD) were carefully cleaned, inspected, and run at 5 L/min and pressure at 100 mmHg in a standard 500 mL mock circulatory loop using bovine blood. The CentriMag was used as a control pump because of its low blood damage profile. Samples were collected at regular intervals and the following were analyzed: complete cell counts, hemolysis, platelet activation, leukocyte-derived microparticles (LMPs), and von Willebrand factor (vWF) degradation.ResultsThe HeartMate 2 had the highest levels of hemolysis and platelet activation after 6 hours compared with the HVAD and CentriMag. A decreased granulocyte count, high numbers of LMPs and CD11b^BrightHLADR⁻ LMPs, and decreased vWF collagen binding activity was most evident in the HVAD.ConclusionsThe results indicate that it is possible to observe differences between different pump designs during in vitro testing that might translate to clinical performance. This study demonstrates the importance of developing standard in vitro total blood damage methods against which device developers could use to modify design to reduce complication risk long before implantation.     

Destination therapy with ventricular assist devices

Despite extensive research and great strides over the past 40 years, the ideal permanent mechanical assist device remains elusive. The incidence of heart failure is increasing, and the number of heart transplants has remained constant. The HeartMate and Novacor are two pulsatile, long-term ventricular assist devices (VADs) commonly used as a bridge to transplantation. Randomized Evaluation of Mechanical Assistance in the Treatment of Congestive Heart Failure is a randomized study of device therapy in heart failure with treatment either with device (HeartMate) therapy or maximal medical therapy which was recently completed and demonstrated a Kaplan-Meier survival rate at 1 year of 52% for the device group compared to 25% in the medical therapy group. The TCI HeartMate is the only device approved for destination therapy, while others such as the Novacor device are in the process of evaluation. Most of these devices are still plagued by mechanical problems, bleeding, thromboembolism and infection. Other promising new devices include smaller VADs using impeller pump technology, such as the Arrow LionHeart, Micromed Debakey pump and Jarvik 2000 pump. The CardioVAD is an interesting chronically implantable balloon pump inserted into the descending thoracic aorta. While experience with the newer implantable pumps is growing, most of them require some manipulation of the heart perioperatively, in addition to anticoagulation postoperatively and careful monitoring for complications and infection.     

Ventricular tachycardia in the era of ventricular assist devices

Sustained ventricular tachycardia (VT) in patients with advanced cardiomyopathy is a potentially life-threatening arrhythmia. Newer treatment strategies have evolved that combine the use of catheter ablation to target the substrate for VT and ventricular assist devices (VADs) to hemodynamically support the failing ventricle. This editorial is targeted to the practicing clinician caring for these difficult patients. The current article reviews the use of percutaneous VADs to support catheter ablation of VT, the use of durable VADs to support the failing heart in patients with recurrent VT, ventricular arrhythmias in patients with durable VADs, and the use of catheter ablation to treat VT in patients with durable VADs.     

High prevalence of Dapsone-induced oxidant hemolysis in North American SCT recipients without glucose-6-phosphate-dehydrogenase deficiency

Dapsone (4-4'-diaminodiphenylsulfone) is commonly used for Pneumocystis jirovecii pneumonia (PCP) prophylaxis in immunocompromised patients. Oxidant hemolysis is a known complication of dapsone, but its frequency in adult patients who have undergone a SCT for hematological malignancies is not well established. We studied the presence of oxidant hemolysis, by combining examination of RBC morphology and laboratory data, in 30 patients who underwent a SCT and received dapsone for PCP prophylaxis, and compared this group with 26 patients who underwent a SCT and received trimethoprim-sulfamethoxazole (TMP-SMX) for PCP prophylaxis. All patients had normal glucose-6-phosphate dehydrogenase (G6PDH) enzymatic activity. In SCT patients, dapsone compared with TMP-SMX for PCP prophylaxis was associated with a high incidence of oxidant hemolysis (87 vs 0%, P<0.001), and the morphological evaluation of oxidant hemolysis correlated well with laboratory evidence of hemolysis. Dapsone-induced oxidant hemolysis in SCT patients is 20-fold higher than the reported rate in the population of HIV-infected patients, and thus much higher than the prevalence of G6PDH variants in the general population. In our patients, it manifested clinically as a lower Hb that was not significant enough to result in increased packed RBC transfusions.     

Mechanical Hemolysis Complicating Transcatheter Interventions for Valvular Heart Disease: JACC State-of-the-Art Review

Mechanical intravascular hemolysis is frequently observed following procedures on heart valves and uncommonly observed in native valvular disease. In most cases, its severity is mild. Nevertheless, it can be clinically significant and even life threatening, requiring multiple blood transfusions and renal replacement therapy. This paper reviews the current knowledge on mechanical intravascular hemolysis in valvular disease, before and after correction, focusing on pathophysiology, approach to diagnosis, and impact of other hematological conditions on the resultant anemia. The importance of a multidisciplinary management is underscored. Laboratory data are provided about subclinical hemolysis that is commonly observed following the implantation of surgical and transcatheter valve prostheses and devices. Finally, clinical scenarios are reviewed and current medical and surgical treatments are discussed, including alternative options for inoperable patients.