Continuous-flow left ventricular assist device support in patients with advanced heart failure: points of interest for the daily management

Listing criteria for heart transplantation in the Netherlands

The updated listing criteria for heart transplantation are presented on behalf of the three heart transplant centres in the Netherlands. Given the shortage of donor hearts, selection of those patients who may expect to have the greatest benefit from a scarce societal resource in terms of life expectancy and quality of life is inevitable. The indication for heart transplantation includes end-stage heart disease not remediable by more conservative measures, accompanied by severe physical limitation while on optimal medical therapy, including ICD/CRT‑D. Assessment of this condition requires cardiopulmonary stress testing, prognostic stratification and invasive haemodynamic measurements. Timely referral to a tertiary centre is essential for an optimal outcome. Chronic mechanical circulatory support is being used more and more as an alternative to heart transplantation and to bridge the progressively longer waiting time for heart transplantation and, thus, has become an important treatment option for patients with advanced heart failure.

Association between splenic volume and pulsatility index in patients with left ventricular assist devices

The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II^® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure (r = 0.431, p = 0.025) and pulmonary capillary wedge pressure (r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (β = -0.452, p = 0.003), pump power (β = -0.325, p = 0.023), and splenic volume (β = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients.

The role of long-term mechanical circulatory support in patients with advanced heart failure

In patients with end-stage heart failure, advanced therapies such as heart transplantation and long-term mechanical circulatory support (MCS) with a left ventricular assist device (LVAD) have to be considered. LVADs can be implanted as a bridge to transplantation or as an alternative to heart transplantation: destination therapy. In the Netherlands, long-term LVAD therapy is gaining importance as a result of increased prevalence of heart failure together with a low number of heart transplantations due to shortage of donor hearts. As a result, the difference between bridge to transplantation and destination therapy is becoming more artificial since, at present, most patients initially implanted as bridge to transplantation end up receiving extended LVAD therapy. Following LVAD implantation, survival after 1, 2 and 3 years is 83%, 76% and 70%, respectively. Quality of life improves substantially despite important adverse events such as device-related infection, stroke, major bleeding and right heart failure. Early referral of potential candidates for long-term MCS is of utmost importance and positively influences outcome. In this review, an overview of the indications, contraindications, patient selection, clinical outcome and optimal time of referral for long-term MCS is given.

Outcome of mechanical circulatory support at the University Medical Centre Utrecht

Background

The prevalence of heart failure (HF) is increasing substantially and, despite improvements in medical therapy, HF still carries a poor prognosis. Mechanical circulatory support (MCS) by a continuous-flow left ventricular assist device (cf-LVAD) improves survival and quality of life in selected patients. This holds especially for the short-term outcome, but experience regarding long-term outcome is growing as the waiting time for heart transplantation is increasing due to the shortage of donor hearts. Here we present our results from the University Medical Centre Utrecht.

Methods

Data of all patients with a cf-LVAD implant between March 2006 and January 2018 were collected. The primary outcome was survival. Secondary outcomes included adverse events defined according to the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) definitions, described per patient year.

Results

A total of 268 patients (69% male, mean age 50 ± 13 years) received a cf-LVAD. After a median follow-up of 542 (interquartile range 205–1044) days, heart transplantation had been performed in 82 (31%) patients, the cf-LVAD had been explanted in 8 (3%) and 71 (26%) had died. Survival at 1, 3 and 5 years was 83%, 72% and 57%, respectively, with heart transplantation, cf-LVAD explantation or death as the end-point. Death was most often caused by neurological complications (31%) or infection (20%). Major bleeding occurred 0.51 times and stroke 0.15 times per patient year.

Conclusion

Not only short-term results but also 5‑year survival after cf-LVAD support demonstrate that MCS is a promising therapy as an extended bridge to heart transplantation. However, the incidence of several major complications still has to be addressed.

Electronic supplementary material

The online version of this article (10.1007/s12471-020-01375-4) contains supplementary material, which is available to authorized users.

Hemostatic complications associated with ventricular assist devices

Hemostatic complications are common in patients with ventricular assist devices. The pathophysiologic mechanisms that lead to dysregulated hemostasis involve complex interactions between device surface, sheer stress, and blood flow. These factors lead to various manifestations that require a thorough understanding of the interplay among platelets, coagulation factors, and red cells. In this article, we review the pathophysiology of hematologic complications (bleeding, acquired von Willebrand disease, heparin-induced thrombocytopenia, hemolysis, stroke and pump thrombosis), the clinical manifestations, and the management of each. We summarize the evidence available for management of these entities and provide a pragmatic clinical review.

The association between novel clinical factors and gastrointestinal bleeding among patients supported with continuous-flow left ventricular assist device therapy

BACKGROUND

This study explores novel preimplantation risk factors associated with gastrointestinal bleeding (GIB) after continuous-flow left ventricular assist device (CF-LVAD) implantation. CF-LVAD therapy implantation for patients with advanced heart failure is associated with a 20% to 40% incidence of GIB.

METHODS

This study includes patients receiving CF-LVAD at a quaternary medical center from 2006 to 2014 (n = 254). The primary endpoint was GIB within 12 months after implantation; the secondary outcome was 3-year all-cause mortality. The Student t test or the χ² test compared continuous or categorical variables. Competing risks analysis calculated the cumulative incidence of GIB postimplantation. Cox proportional hazards model was used for univariate/multivariate models predicting GIB.

RESULTS

Sixty-four patients had GIB, with incidence rates at 1, 3, and 12 months of 11.8%, 19.3%, and 25.2%, respectively. Endoscopy revealed no identified source of bleeding in 41%; 33% of lesions were localized in the upper gastrointestinal tract, with the bulk (39%) categorized as vascular. Patients with prior gastrointestinal abnormalities (n = 98) had a greater risk of GIB post-CF-LVAD (HR 1.85 [1.11-3.09]; P = 0.02) than those with normal gastrointestinal evaluation results (n = 45) and those without preimplantation gastrointestinal evaluation (n = 111). Baseline blood urea nitrogen, chronic obstructive pulmonary disease, and prior percutaneous coronary intervention were statistically associated with post-CF-LVAD GIB. The presence of GIB within 12 months of CF-LVAD implantation was associated with an increased risk of 3-year all-cause mortality (HR 2.57 [1.57-4.15]; P < 0.01).

CONCLUSIONS

First-year GIB is associated with increased mortality post-CF-LVAD. We advocate a closer examination of several GIB risk factors when evaluating CF-LVAD candidates.

In Vivo Evaluation of Active and Passive Physiological Control Systems for Rotary Left and Right Ventricular Assist Devices

Preventing ventricular suction and venous congestion through balancing flow rates and circulatory volumes with dual rotary ventricular assist devices (VADs) configured for biventricular support is clinically challenging due to their low preload and high afterload sensitivities relative to the natural heart. This study presents the in vivo evaluation of several physiological control systems, which aim to prevent ventricular suction and venous congestion. The control systems included a sensor-based, master/slave (MS) controller that altered left and right VAD speed based on pressure and flow; a sensor-less compliant inflow cannula (IC), which altered inlet resistance and, therefore, pump flow based on preload; a sensor-less compliant outflow cannula (OC) on the right VAD, which altered outlet resistance and thus pump flow based on afterload; and a combined controller, which incorporated the MS controller, compliant IC, and compliant OC. Each control system was evaluated in vivo under step increases in systemic (SVR ∼1400-2400 dyne/s/cm(5) ) and pulmonary (PVR ∼200-1000 dyne/s/cm(5) ) vascular resistances in four sheep supported by dual rotary VADs in a biventricular assist configuration. Constant speed support was also evaluated for comparison and resulted in suction events during all resistance increases and pulmonary congestion during SVR increases. The MS controller reduced suction events and prevented congestion through an initial sharp reduction in pump flow followed by a gradual return to baseline (5.0 L/min). The compliant IC prevented suction events; however, reduced pump flows and pulmonary congestion were noted during the SVR increase. The compliant OC maintained pump flow close to baseline (5.0 L/min) and prevented suction and congestion during PVR increases. The combined controller responded similarly to the MS controller to prevent suction and congestion events in all cases while providing a backup system in the event of single controller failure.

Left Ventricular Assist Device Results: Single Center Experience

OBJECTIVES

The number of patients with end-stage cardiac failure who are waiting for transplant has been increasing, although number of heart donations stays limited. This has resulted in an increased use of left ventricular assist devices. Here, we present results of patients who received left ventricular assist device implants at Baskent University Ankara Hospital.

MATERIALS AND METHODS

We retrospectively evaluated 24 patients who received a HeartWare left ventricular assist device (HeartWare Inc, Framingham, MA, USA) between April 2012 and February 2015; 2 patients (8.33%) were female.

RESULTS

Patients had end-stage heart failure as a result of the following causes: 11 patients (45%) had ischemic cardiomyopathy, 12 patients (50%) had dilated cardiomyopathy, and 1 patient (4.1%) had acute myocarditis. Regarding use of the left ventricular assist device, 10 patients (41.6%) had the device as destination therapy, and the remaining 14 patients (48.6%) had it as bridge to transplant. The Interagency Registry for Mechanically Assisted Circulatory Support Profile was 1 for 3 patients (12.5%), 2 for 9 patients (37.5%), and 3 for 12 patients (50%). Mean follow-up was 239.8 days, and the mortality rate was 33.3% (8 patients died). During follow-up, we found that 3 patients (12.5%) had received a heart transplant and 1 patient (4.1%) eventually recovered, with the device extracted. Six patients had driveline infections, and 3 patients had cerebrovascular events.

CONCLUSIONS

With the insufficient number of cardiac donors, use of a left ventricular assist device for patients with end-stage cardiac failure who are awaiting transplant may be the best option.

The diagnosis of left ventricular assist device thrombosis

The clinical course of a patient with a left ventricular assist device is described. A total of 6 weeks after device insertion, the lactate dehydrogenase (LDH) level increased to 2801 U/l despite adding low-molecular-weight heparin to acenocoumarol and aspirin. Pump thrombosis was suspected but unconfirmed by computed tomography. Increased pump power requirement did not occur. Instituting unfractionated heparin caused a drop in the LDH level. After discontinuing heparin, the LDH levels rose to 5529 U/l whereupon pump replacement was performed. LDH levels, combined with clinical deterioration and right heart catheterisation, led to the diagnosis of pump thrombosis.

A compliant, banded outflow cannula for decreased afterload sensitivity of rotary right ventricular assist devices

Biventricular support with dual rotary ventricular assist devices (VADs) has been implemented clinically with restriction of the right VAD (RVAD) outflow cannula to artificially increase afterload and, therefore, operate within recommended design speed ranges. However, the low preload and high afterload sensitivity of these devices increase the susceptibility of suction events. Active control systems are prone to sensor drift or inaccurate inferred (sensor-less) data, therefore an alternative solution may be of benefit. This study presents the in vitro evaluation of a compliant outflow cannula designed to passively decrease the afterload sensitivity of rotary RVADs and minimize left-sided suction events. A one-way fluid-structure interaction model was initially used to produce a design with suitable flow dynamics and radial deformation. The resultant geometry was cast with different initial cross-sectional restrictions and concentrations of a softening diluent before evaluation in a mock circulation loop. Pulmonary vascular resistance (PVR) was increased from 50 dyne s/cm(5) until left-sided suction events occurred with each compliant cannula and a rigid, 4.5 mm diameter outflow cannula for comparison. Early suction events (PVR ∼ 300 dyne s/cm(5) ) were observed with the rigid outflow cannula. Addition of the compliant section with an initial 3 mm diameter restriction and 10% diluent expanded the outflow restriction as PVR increased, thus increasing RVAD flow rate and preventing left-sided suction events at PVR levels beyond 1000 dyne s/cm(5) . Therefore, the compliant, restricted outflow cannula provided a passive control system to assist in the prevention of suction events with rotary biventricular support while maintaining pump speeds within normal ranges of operation.

Pathophysiology and potential treatments of pulmonary hypertension due to systolic left heart failure

Pulmonary hypertension (PH) due to left heart failure is becoming increasingly prevalent and is associated with poor outcome. The precise pathophysiological mechanisms behind PH due to left heart failure are, however, still unclear. In its early course, PH is caused by increased left ventricular filling pressures, without pulmonary vessel abnormalities. Conventional treatment for heart failure may partly reverse such passive PH by optimizing left ventricular function. However, if increased pulmonary pressures persist, endothelial damage, excessive vasoconstriction and structural changes in the pulmonary vasculature may occur. There is, at present, no recommended medical treatment for this active component of PH due to left heart failure. However, as the vascular changes in PH due to left heart failure may be similar to those in pulmonary arterial hypertension (PAH), a selected group of these patients may benefit from PAH treatment targeting the endothelin, nitric oxide or prostacyclin pathways. Such potent pulmonary vasodilators could, however, be detrimental in patients with left heart failure without pulmonary vascular pathology, as selective pulmonary vasodilatation may lead to further congestion in the pulmonary circuit, resulting in pulmonary oedema. The use of PAH therapies is therefore currently not recommended and would require the selection of suitable patients based on the underlying causes of the disease and careful monitoring of their progress. The present review focuses on the following: (i) the pathophysiology behind PH resulting from systolic left heart failure, and (ii) the current evidence for medical treatment of this condition, especially the role of PAH-targeted therapies in systolic left heart failure.

Outcomes of continuous flow ventricular assist devices

Heart transplantation is commonplace, the supply is limited. Many exciting changes in the field of mechanical circulatory support have occurred in the past few years, including the axial flow pump. Left ventricular assist device (LVAD) therapy is ever evolving. As the use of LVAD therapy increases it is important to understand the indications, surgical considerations and outcomes.

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.

Implantation of the continuous flow HeartWare® left ventricular assist device

Recent outstanding clinical advances with new mechanical circulatory systems have led to additional strategies in the treatment of end-stage heart failure. Heart transplantation can be postponed and for certain patients even replaced by smaller implantable left ventricular assist devices (LVADs). Mechanical support of the failing left ventricle enables appropriate haemodynamic stabilization and recovery of secondary organ failure, often seen in these severely ill patients. These new devices may be of great help to bridge patients until a suitable cardiac allograft is available but are also discussed as definitive treatment for patients who do not qualify for transplantation. Main indications for LVAD implantation are bridge to recovery, bridge to transplantation or destination therapy. An LVAD may be an important tool for patients with an expected prolonged period on the waiting list, for instance those with blood group O or B, with high or low body weight and those with potentially reversible secondary organ failure and pulmonary artery hypertension. However, LVAD implantation means an additional heart operation with inherent perioperative risks and complications during the waiting period. Finally, cardiac transplantation in patients with prior implantation of an LVAD represents a surgical challenge. The care of patients after the implantation of miniaturized LVADs, such as the HeartWare® system, seems to be easier than following pulsatile devices. The explantation of such devices at the time of transplantation is technically more comfortable than after HeartMate II implantation.

Cyclophosphamide-Induced Cardiomyopathy: A Case Report, Review, and Recommendations for Management

Cyclophosphamide is increasingly used to treat various types of cancers and autoimmune conditions. Higher doses of this drug may produce significant cardiac toxicity, including fatal hemorrhagic myocarditis. In this review, we present a case of cyclophosphamide-induced cardiomyopathy requiring mechanical circulatory support. We also describe the pathophysiology, clinical manifestations, and risk factors for this important clinical entity and propose early detection and management strategies.

Use of implantable cardioverter defibrillators in patients with left ventricular assist devices

Patients with left ventricular assist devices (LVADs) are at high risk of sustained ventricular arrhythmias, but these may be remarkably well tolerated and the association with sudden death is unclear. Many patients who receive an LVAD already have an implantable cardioverter defibrillator (ICD). While it is standard practice to reactivate a previously implanted ICD in an LVAD recipient, this should include discussion of the revised risks and benefits of ICD therapy following LVAD implantation. In particular, patients should be warned that they might receive a significant number of ICD shocks that may not be life saving. When ICDs are reactivated, device programming should minimize the risk of repeated shocks for non-sustained or well-tolerated ventricular arrhythmias. Implantation of a primary prevention ICD after implantation of an LVAD is not supported by current evidence, poses potential risks, and should be the subject of a clinical trial before it becomes standard practice.