HeartWare continuous-flow ventricular assist device thrombosis: the Bad Oeynhausen experience

Outcomes Following Left Ventricular Assist Device Exchange: Focus on the Impacts of Device Infection

Hemodynamic support with continuous-flow left ventricular assist device (CF-LVAD) therapy has proven a reliable treatment for advanced heart failure. Although modern LVADs are highly durable, device failure and infection can be resolved with surgical exchange of pump components. In this study, we investigated the incidence and outcomes of LVAD exchange with the HeartMate II and HeartWare HVAD. Data were obtained from 677 patients who underwent CF-LVAD implantation between 2005 and 2016. Patients who underwent a device exchanged were included. The primary outcomes were length of hospital stay and mortality. Of the 677 patients included in this study, 72 (10.6%) required LVAD exchange. Thirty-day and 1-year mortality rates were comparable to primary LVAD implantation: 4.3% vs. 3.49%, p = 0.727 and 20.3% vs. 20.7%, p = 0.989, respectively. Thirty-one patients (4.5%) underwent exchange with ongoing infection. Kaplan-Meier analysis indicated significant differences in survival between groups based on indication for exchange. Patients who underwent exchange after more than 150 days of active infection suffered worse postexchange survival than those who underwent exchanged earlier (P = 0.007). While exchange was required only in 10.6% of patients undergoing LVAD implantation, our results show device exchange may be executed safely and effectively, with long-term outcomes similar to primary LVAD implantation. The indication for device exchange impacts postexchange outcomes, and those exchanged with LVAD infection tend to fare worse than those exchanged for device malfunction or thrombus. Patients who are exchanged with active infection have better postoperative survival if the exchange is performed expeditiously after medical management has failed.

In vitro Hemocompatibility Evaluation of the HeartWare Ventricular Assist Device Under Systemic, Pediatric and Pulmonary Support Conditions

The development of adult use right ventricular assist devices (RVADs) and pediatric left ventricular assist devices (pediatric LVADs) have significantly lagged behind compared to adult use left ventricular assist devices (LVADs). The HeartWare ventricular assist device (HVAD) intended to be used for adult's systemic support, is increasingly used off-label for adult pulmonary and pediatric systemic support. Due to different hemodynamics and physiology, however, the HVAD's hemocompatibility profiles can be drastically different when used in adult pulmonary circulation or in children, compared to its intended usage state, which could have a direct clinical and developmental relevance. Taking these considerations in mind, we sought to conduct in vitro hemocompatibility testing of HVAD in adult systemic, pediatric systemic and adult pulmonary support conditions. Two HVADs coupled to custom-built blood circulation loops were tested for 6 hours using bovine blood at 37°C under adult systemic, pediatric systemic, and adult pulmonary flow conditions (flow rate = 5.0, 2.5, and 4.5 L/min; differential pressure = 100, 69, and 20 mm Hg, respectively). Normalized index of hemolysis for adult systemic, pediatric systemic, and adult pulmonary conditions were 0.0083, 0.0039, and 0.0017 g/100 L, respectively. No significant difference was seen in platelet activation for these given conditions. High molecular weight von Willebrand factor multimer degradation was evident in all conditions (p < 0.05). In conclusion, alterations in the usage mode produce substantial differences in hemocompatibility of the HVAD. These findings would not only have clinical relevance but will also facilitate future adult use RVAD and pediatric LVAD development.

A Stepwise Approach to Left Ventricular Assist Device Pump Thrombosis

AIM

Pump thrombosis (PT) is a detrimental complication of left ventricular assist device (LVAD) therapy. There is no consensus on optimal PT treatment. The aim of this study was to present a treatment strategy for patients with PT.

METHOD

The hospital records of patients who underwent isolated LVAD implantation between May 2013 and October 2018 were retrospectively evaluated. Pump thrombosis was suspected in the setting of impaired flow/power parameters and haemolysis. Protocols for the management of suspected PT varied by patient presentation. Parameters that increased the PT risk were investigated by dividing the patients into two groups according to the presence of PT. Preoperative and operative data were analysed.

RESULTS

Pump thrombosis was observed in 20 of 81 patients. All patients with PT presented elevated lactate dehydrogenase levels and higher power and/or low-/high-flow alarm at admission. All patients were treated initially with intravenous unfractionated heparin infusion; three patients did not require further treatment, one patient died due to sudden cardiac arrest, and three patients underwent urgent surgery for LVAD exchange. Thirteen (13) patients received tissue plasminogen activator infusion; eight were discharged without any signs of thrombosis, and three were bridged to transplant. One (1) major bleeding event leading to death was observed. Freedom from second PT was found in 91% cases at 6 months and in 68.2% at 1 year. We found that a larger left ventricle and the type of pump determined the risk of PT.

CONCLUSIONS

Low-dose thrombolytic therapy should be considered as a feasible treatment option for patients with PT.

Insight into Atrial Fibrillation in LVAD Patients: From Clinical Implications to Prognosis

The use of left ventricular assist devices (LVADs), whether for destination therapy or bridge to transplantation, has gained increasing validation in recent years in patients with advanced heart failure. Arrhythmias can be the most challenging variables in the management of such patients but the main attention has always been focused on ventricular arrhythmias given the detrimental impact on mortality. Nevertheless, atrial fibrillation (AF) is the most common rhythm disorder associated with advanced heart failure and may therefore characterize the LVADs' pre- and postimplantation periods. Indeed, the consequences of AF in the population suffering from standard heart failure may require a more comprehensive evaluation in the presence of or in sight of an LVAD, making the AF clinical management in these patients potentially complex. Several studies have been based on this subject with different and often conflicting results, leaving many questions unresolved. The purpose of this review is to summarize the main pieces of evidence about the clinical impact of AF in LVAD patients, underlining the main implications in terms of hemodynamics, thromboembolic risk, bleeding and prognosis. Therapeutic considerations about the clinical management of these patients are also made according to the latest evidence.

Antithrombotic therapy in ventricular assist device (VAD) management: From ancient beliefs to updated evidence. A narrative review

Platelets play a key role in the pathogenesis of ventricular assist device (VAD) thrombosis; therefore, antiplatelet drugs are essential, both in the acute phase and in the long-term follow-up in VAD management. Aspirin is the most used agent and still remains the first-choice drug for lifelong administration after VAD implantation. Anticoagulant drugs are usually recommended, but with a wide range of efficacy targets. Dual antiplatelet therapy, targeting more than one pathway of platelet activation, has been used for patients developing a thrombotic event, despite an increased risk of bleeding complications. Although different strategies have been attempted, bleeding and thrombotic events remain frequent and there are no uniform strategies adopted for pharmacological management in the short and mid- or long-term follow up. The aim of this article is to provide an overview of the evidence from randomized clinical trials and observational studies with a focus on the pathophysiologic mechanisms underlying bleeding and thrombosis in VAD patients and the best antithrombotic regimens available.

Medical Management of Pump-Related Thrombosis in Patients with Continuous-Flow Left Ventricular Assist Devices: A Systematic Review and Meta-Analysis

Pump thrombosis is a dreaded complication of left ventricular assist devices (LVADs). We completed a systematic review to evaluate the efficacy and complications associated with medical management of LVAD thrombosis. Databases were searched using the terms "vad*" or "ventricular assist device" or "heart assist device" and "thrombus" or "thrombosis" or "thromboembolism." Of 2,383 manuscripts, 49 articles met the inclusion criteria. The risk of partial or no resolution of LVAD thrombosis did not significantly differ between thrombolytic and nonthrombolytic regimens (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.20-1.16). When response to therapy was evaluated based on pump type, there were no significant differences in how patients with a HeartMate II or HeartWare ventricular assist device responded to thrombolytic or nonthrombolytic treatment. Pooled risk of major bleeding in the thrombolytic group was 29% (95% CI, 0.17-0.44) and 12% (95% CI, 0.01-0.57) in the nonthrombolytic group. Odds of death did not differ between thrombolytic and nonthrombolytic regimens (OR, 1.28; 95% CI, 0.42-3.89). Although thrombolytic and nonthrombolytic treatment similarly resolved LVAD thrombosis, major hemorrhage may be increased with the use of thrombolysis. Randomized clinical trials comparing thrombolytic and nonthrombolytic treatment of LVAD thrombosis are needed to establish the most effective and safe option for patients who are not surgical candidates.

Thrombosis in Left Ventricular Assistance Device with Centrifugal Technology: Is Early Thrombolysis a Better Solution?

Background

Continuous flow left ventricular assistance devices (CF-LVADs) have revolutionized the treatment of advanced heart failure. Pump replacement for thrombosis is a high-risk procedure with a high perioperative mortality rate with possible recurrence. We aim to summarize our experience using a conservative approach with medical therapy.

Methods

We retrospectively reviewed records of patients who experienced pump thrombosis after LVAD implantation with HeartWare HVAD at our institution, from November 2010 to March 2016. Device thrombosis (DT) was divided into suspected (SDT) and confirmed (CDT). A conservative approach using thrombolysis and heparin was used in all patients.

Results

A total of 32 HeartWare HVAD pumps were implanted. Mean age was 59 ± 10 years and the mean time on mechanical support was 19.29 months (± 14.06). Pump thrombosis occurred in 7 patients (0.14 patients/year) after a mean time of 733 (231–1,606) days after LVAD implantation. Three out of 7 cases had thrombosis recurrence (43%). Overall 19 episodes were recorded (0.38 event per patient/year). Eighteen out of 19 thrombolytic treatments were successful (94.7%). No patient required LVAD replacement or transfusion of blood products. There was no significant difference in terms of survival between patients who experienced thrombotic events and patients who did not. No major complications related to thrombolysis were recorded.

Conclusions

Systemic thrombolysis plus heparin was an excellent therapeutic option. Early intervention in clinically stable patients without signs of heart failure but with indirect signs of device thrombosis has led to better outcomes.

Intravenous thrombolytic therapy for patients with ventricular assist device thrombosis: An attempt to avoid reoperation

A growing number of patients are undergoing prolonged management of advanced heart failure with the use of continuous flow left ventricular assist devices (LVADs). Subsequently, an increasing number of patients are presenting with complications associated with these devices. Based on an analysis of three major LVAD institutions, the number of patients developing LVAD pump thrombosis may be much higher than originally projected.[12] The management of this highly feared complication continues to be challenging, as the population of LVAD patients is very heterogeneous and heavily burdened with comorbidities. The standard protocol of increasing anticoagulation may fail to achieve successful resolution of thrombus. Difficulty and poor prognosis may make reoperation less than desirable. Here, we present a case of successful thrombolysis following intravenous administration of tissue plasminogen activator in the Intensive Care Unit setting.

HeartWare left ventricular assist device for the treatment of advanced heart failure

The importance of mechanical circulatory support in the therapy of advanced heart failure is steadily growing. The rapid developments in the field of mechanical support are characterized by continuous miniaturization and enhanced performance of the assist devices, providing increased pump durability and prolonged patient survival. The HeartWare left ventricular assist device system (HeartWare Inc., Framingham, MA, USA) is a mechanical ventricular assist device with over 8000 implantations worldwide. Compared with other available assist devices it is smaller in size and used in a broad range of patients. The possibility of minimally invasive procedures is one of the major benefits of the device – allowing implants and explants, as well as exchanges of the device with reduced surgical impact. We present here a review of the existing literature on the treatment of advanced heart failure using the HeartWare left ventricular assist device system.

Device-Related Thrombosis in Continuous-Flow Left Ventricular Assist Device Support

Advanced heart failure therapy has been revolutionized with the advent of continuous-flow ventricular assist devices (CF-LVADs) which have improved both survival and quality of life. Despite this, support with CF-LVADs is frequently complicated, with 70% of recipients experiencing a major complication in the first year of durable support. The most concerning of these complications to emerge is device-related thrombosis, which is associated with increased morbidity and mortality. Pathophysiology and diagnosis are multifaceted and complex, with pump-specific and patient-specific factors to be considered. Incidence estimates are evolving with increases seen in the past 2 years compared with earlier implant data. Evidence for treatment is limited to case series and reports, which are subject to significant publication bias. Finally, appropriate primary and secondary prophylaxis is imprecise with multiple antiplatelet and antithrombotic strategies described. This review seeks to summarize the current literature surrounding the pathophysiology, diagnosis, and management of thrombosis in CF-LVAD recipients.

Identification and Management of Pump Thrombus in the HeartWare Left Ventricular Assist Device System: A Novel Approach Using Log File Analysis

OBJECTIVES

The study sought to characterize patterns in the HeartWare (HeartWare Inc., Framingham, Massachusetts) ventricular assist device (HVAD) log files associated with successful medical treatment of device thrombosis.

BACKGROUND

Device thrombosis is a serious adverse event for mechanical circulatory support devices and is often preceded by increased power consumption. Log files of the pump power are easily accessible on the bedside monitor of HVAD patients and may allow early diagnosis of device thrombosis. Furthermore, analysis of the log files may be able to predict the success rate of thrombolysis or the need for pump exchange.

METHODS

The log files of 15 ADVANCE trial patients (algorithm derivation cohort) with 16 pump thrombus events treated with tissue plasminogen activator (tPA) were assessed for changes in the absolute and rate of increase in power consumption. Successful thrombolysis was defined as a clinical resolution of pump thrombus including normalization of power consumption and improvement in biochemical markers of hemolysis. Significant differences in log file patterns between successful and unsuccessful thrombolysis treatments were verified in 43 patients with 53 pump thrombus events implanted outside of clinical trials (validation cohort).

RESULTS

The overall success rate of tPA therapy was 57%. Successful treatments had significantly lower measures of percent of expected power (130.9% vs. 196.1%, p = 0.016) and rate of increase in power (0.61 vs. 2.87, p < 0.0001). Medical therapy was successful in 77.7% of the algorithm development cohort and 81.3% of the validation cohort when the rate of power increase and percent of expected power values were <1.25% and 200%, respectively.

CONCLUSIONS

Log file parameters can potentially predict the likelihood of successful tPA treatments and if validated prospectively, could substantially alter the approach to thrombus management.

Banding the Right Ventricular Assist Device Outflow Conduit: Is It Really Necessary With Current Devices?

Implantable left ventricular assist devices (LVADs) have been adapted clinically for right-sided mechanical circulatory support (RVAD). Previous studies on RVAD support have established the benefits of outflow cannula restriction and rotational speed reduction, and recent literature has focused on assessing either the degree of outflow cannula restriction required to simulate left-sided afterload, or the limitation of RVAD rotational speeds. Anecdotally, the utility of outflow cannula restriction has been questioned, with suggestion that banding may be unnecessary and may be replaced simply by varying the outflow conduit length. Furthermore, many patients have a high pulmonary vascular resistance (PVR) at the time of ventricular assist device (VAD) insertion that reduces with pulmonary vascular bed remodeling. It is therefore important to assess the potential changes in flow through an RVAD as PVR changes. In this in vitro study, we observed the use of dual HeartWare HVAD devices (HeartWare Inc., Framingham, MA, USA) in biventricular support (BiVAD) configuration. We assessed the pumps' ability to maintain hemodynamic stability with and without banding; and with varying outflow cannulae length (20, 40, and 60 cm). Increased length of the outflow conduit was found to produce significantly increased afterload to the device, but this was not found to be necessary to maintain the device within the manufacturer's recommended operational parameters under a simulated normal physiological setting of mild and severe right ventricular (RV) failure. We hypothesize that 40 cm of outflow conduit, laid down along the diaphragm and then up over the RV to reach the pulmonary trunk, will generate sufficient resistance to maintain normal pump function.

Does CircuLite Synergy assist device as partial ventricular support have a place in modern management of advanced heart failure?

The discrepancy between the number of patients on the waiting list and available donor hearts has led to the successful development of left ventricular assist devices (LVAD) as a bridge to transplantation. The conventional LVADs are designed to provide full hemodynamic support for the end-stage failing heart. However, full-support LVAD implantation requires major surgery, sternotomy and cardiopulmonary bypass in majority of cases. The Synergy Micro-pump is the smallest implantable LVAD and provides partial flow support up to 3 l/min. It was shown that early intervention with this device can provide substantial benefits to patients with severe heart failure not yet sick enough for a full-support LVAD. Due the small dimensions it can be implanted without cardiopulmonary bypass or a sternotomy. The purpose of this article is to review the clinical use of the Synergy Micro-pump as partial hemodynamic support.

Successful repeated thrombolysis in a patient with HeartWare thrombosis - the importance of Doppler flow pattern

Here we present a patient after implantation of a left ventricular assist device (HeartWare) for destination therapy complicated by recurrent thrombosis of the device. At 14 months after implantation, the patient presented with a pump thrombosis after an INR incompliance period. A surgical pump exchange was performed and the patient recovered uneventfully. Five months later a pump thrombosis occurred again, and the patient refused surgery. Systemic thrombolysis was carried out this time. Three and 6 months later the same clinical picture was presented again, and repeat thrombolysis was performed successfully. The patient was discharged and has remained stable since, without any symptoms of thrombosis of the device.

Thrombosis in continuous-flow left ventricular assist devices: pathophysiology, prevention, and pharmacologic management

Continuous-flow left ventricular assist devices reduce short-term mortality and improve quality of life in patients with end-stage heart failure. Unfortunately, device-related complications remain common, with many patients experiencing adverse events within the first year. New literature suggests that rates of device-related thrombosis may be increasing since 2011, which is particularly troublesome given that this pathology can result in a disabling stroke, organ damage, and death. In 2013, a group of practitioners in the field of mechanical circulatory support published a treatment algorithm based on their expert opinion. However, a comprehensive review of the pharmacotherapy of this condition is lacking. A search of the literature revealed 20 separate publications of case reports or case series describing outcomes associated with the use of drug therapy for suspected pump thrombosis. Each of these experiences was limited by small sample size, nonrandomized treatment allocation, and nonstandardized medication dosing. Data describing the outcomes of surgical versus medical management of device thrombosis are also sparse, with only three published reports identified. Based on the review of this limited literature, surgical management appears to be the preferred treatment modality, especially in those with organ hypoperfusion or hemodynamic instability. In patients ineligible for surgery, pharmacotherapy options remain limited. Use of all drug classes described in the literature for the HeartMate II device-fibrinolytics, glycoprotein IIb/IIIa inhibitors, and direct thrombin inhibitors-was hindered by either marginal efficacy or bleeding. Based on historical experience with unfractionated heparin in patients under HeartMate II support, we recommend this agent as a possible option for those with suspected pump thrombosis in lieu of surgical device exchange. For the HeartWare HVAD, limited data suggest that direct intraventricular administration of alteplase may be an acceptable treatment alternative. Additional research is clearly needed to further delineate the role of pharmacotherapy and to identify the optimal agent for managing this potentially life-threatening condition.

Outcomes after implantation of 139 full-support continuous-flow left ventricular assist devices as a bridge to transplantation

OBJECTIVES

Left ventricular assist devices (LVADs) are a routine treatment for patients with advanced heart failure as a bridge to transplantation. The aim of this study was to present our institutional experience and mid-term outcomes after implantation of 139 continuous-flow (cf) LVADs as a bridge to transplantation.

METHODS

One hundred and thirty-nine consecutive LVAD implantations were performed in our institution between July 2007 and August 2013. The mean age of the population was 44.0 ± 13.7 years and 24 (17%) of the patients were female. A substantial number of the patients were on preoperative mechanical support: 35 (25%) with an intra-aortic balloon pump, 9 (6.5%) with an extracorporeal membrane oxygenator and 25 (18%) with previous LVAD, for LVAD exchange.

RESULTS

The mean support duration was 514 ± 481 days, whereas the longest support duration was 2493 days (>6 years). The overall cumulative survival rate following cfLVAD implantation was 89% at 30 days, 76% at 1 year and 66% at 2 years (Fig. 1). There was a statistically significant difference in survival in favour of first LVAD implantation compared with VAD exchange: 91 vs 80% at 30 days, 79 vs 57% at 1 year and 70 vs 43% at 2 years (log-rank P = 0.010). Postoperatively, patients had a significant improvement in end-organ function 1 month after LVAD implantation. In addition, comparison of two different devices [HeartMate II (HM II) and HeartWare] using propensity score matching showed no significant differences in survival and most postoperative adverse events. However, patients supported with HM II required significantly more units of fresh frozen plasma (P = 0.020) with a trend towards a higher use of red blood cells (P = 0.094), and were also more likely to develop percutaneous site infections (P = 0.022).

CONCLUSIONS

HM II and HeartWare cfLVADs have excellent early postoperative outcomes and good mid-term survival, despite a considerable number of patients needing VAD exchange.

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.

Peripheral extracorporeal membrane oxygenation as short-term right ventricular support after HeartWare left ventricular assist device implantation

Left ventricular assist device (LVAD) implantation is associated with the risk of early postoperative right heart dysfunction, which may require urgent institution of mechanical right ventricular support. This is conventionally achieved by cannulation of the femoral vein or right atrial appendage for the inflow and the pulmonary artery for the outflow. However, this requires resternotomy with increased risk of wound and device infection, as well as excessive bleeding. We describe the use of peripheral venoarterial extracorporeal membrane oxygenation as a short-term treatment of right heart failure after HeartWare LVAD implantation.

In vitro and in vivo characterization of three different modes of pump operation when using a left ventricular assist device as a right ventricular assist device

Dual rotary left ventricular assist devices (LVADs) have been used clinically to support patients with biventricular failure. However, due to the lower vascular resistance in the pulmonary circulation compared with its systemic counterpart, excessively high pulmonary flow rates are expected if the right ventricular assist device (RVAD) is operated at its design LVAD speed. Three possible approaches are available to match the LVAD to the pulmonary circulation: operating the RVAD at a lower speed than the LVAD (mode 1), operating both pumps at their design speeds (mode 2) while relying on the cardiovascular system to adapt, and operating both pumps at their design speeds while restricting the diameter of the RVAD outflow graft (mode 3). In this study, each mode was characterized using in vitro and in vivo models of biventricular heart failure supported with two VentrAssist LVADs. The effect of each mode on arterial and atrial pressures and flow rates for low, medium, and high vascular resistances and three different contractility levels were evaluated. The amount of speed/diameter adjustment required to accommodate elevated pulmonary vascular resistance (PVR) during support with mode 3 was then investigated. Mode 1 required relatively low systemic vascular resistance to achieve arterial pressures less than 100 mm Hg in vitro, resulting in flow rates greater than 6 L/min. Mode 2 resulted in left atrial pressures above 25 mm Hg, unless left heart contractility was near-normal. In vitro, mode 3 resulted in expected arterial pressures and flow rates with an RVAD outflow diameter of 6.5 mm. In contrast, all modes were achievable in vivo, primarily due to higher RVAD outflow graft resistance (more than 500 dyn·s/cm(5)), caused by longer cannula. Flow rates could be maintained during instances of elevated PVR by increasing the RVAD speed or expanding the outflow graft diameter using an externally applied variable graft occlusion device. In conclusion, suitable hemodynamics could be produced by either restricting or not restricting the right outflow graft diameter; however, the latter required an operation of the RVAD at lower than design speed. Adjustments in outflow restriction and/or RVAD speed are recommended to accommodate varying PVR.

Staged and effortless explantation of CircuLite Synergy micropump

Synergy(®) micropump was implanted as a bridge to heart transplantation in a middle-age lady with chronic advanced heart failure due to dilated cardiomyopathy. After a good initial recovery, patient was discharged to ward, where her stay was prolonged due to non-healing operative wound over the micropump and recurrent gastrointestinal bleeding. After 3 months of therapy, the heart seemed to be recovered and the micropump was explanted. In view of the patient's bleeding tendency, the micropump was explanted in staged manner.

Isolation of outflow graft of a clotted ventricular assist device with recovery of cardiac function

Ventricular assist device (VAD) thrombosis, though uncommon, is a well-known complication. A HeartWare VAD implanted 2 years ago in a middle-aged man stopped because of thrombosis in the VAD. Because the patient's left ventricular function was recovered by the time of intervention, only the outflow graft was isolated and cut, leaving the pump in place.

An analysis of pump thrombus events in patients in the HeartWare ADVANCE bridge to transplant and continued access protocol trial

BACKGROUND

The HeartWare left ventricular assist device (HVAD, HeartWare Inc, Framingham, MA) is the first implantable centrifugal continuous-flow pump approved for use as a bridge to transplantation. An infrequent but serious adverse event of LVAD support is thrombus ingestion or formation in the pump. In this study, we analyze the incidence of pump thrombus, evaluate the comparative effectiveness of various treatment strategies, and examine factors pre-disposing to the development of pump thrombus.

METHODS

The analysis included 382 patients who underwent implantation of the HVAD as part of the HeartWare Bridge to Transplant (BTT) and subsequent Continued Access Protocol (CAP) trial. Descriptive statistics and group comparisons were generated to analyze baseline characteristics, incidence of pump thrombus, and treatment outcomes. A multivariate analysis was performed to assess significant risk factors for developing pump thrombus.

RESULTS

There were 34 pump thrombus events observed in 31 patients (8.1% of the cohort) for a rate of 0.08 events per patient-year. The incidence of pump thrombus did not differ between BTT and CAP. Medical management of pump thrombus was attempted in 30 cases, and was successful in 15 (50%). A total of 16 patients underwent pump exchange, and 2 underwent urgent transplantation. Five patients with a pump thrombus died after medical therapy failed, 4 of whom also underwent a pump exchange. Survival at 1 year in patients with and without a pump thrombus was 69.4% and 85.5%, respectively (p = 0.21). A multivariable analysis revealed that significant risk factors for pump thrombus included a mean arterial pressure > 90 mm Hg, aspirin dose ≤ 81 mg, international normalized ratio ≤ 2, and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile level of ≥ 3 at implant.

CONCLUSIONS

Pump thrombus is a clinically important adverse event in patients receiving an HVAD, occurring at a rate of 0.08 events per patient-year. Significant risk factors for pump thrombosis include elevated blood pressure and sub-optimal anti-coagulation and anti-platelet therapies. This suggests that pump thrombus event rates could be reduced through careful adherence to patient management guidelines.

Algorithm for the diagnosis and management of suspected pump thrombus

Pump thrombosis is a dreaded complication of long-term implantable ventricular assist devices. No guidance exists regarding the diagnosis and management of this entity despite its significant morbidity. After considerable thought and deliberation, a group of leading investigators in the field of mechanical support propose an algorithm for the diagnosis and management of this vexing entity based on clinical symptoms and serologic and imaging studies.

Can learning to interpret pump messages help lead to an early diagnosis of HeartWare ventricular assist device thrombosis?

Left ventricular assist device thrombosis is a detrimental complication that, if not properly diagnosed and treated, can lead to low output syndrome and death. When ongoing thrombus formation is caused by inappropriate anticoagulation, timely identification is possible, and could perhaps be the key to successful treatment.

Mechanical circulatory support for heart failure: past, present and a look at the future

Heart transplantation remains the gold standard for long-term cardiac replacement, but a shortage of donor organs will always limit this option. For both transplant-eligible and noneligible patients, advances in mechanical circulatory support have revolutionized the options for the management of end-stage heart failure, and this technology continues to bring us closer to a true alternative to heart transplantation. This review provides a perspective on the past, present and future of mechanical circulatory support and addresses the changes in technology, patient selection and management strategies needed to have this therapy fully embraced by the heart failure community, and perhaps replace heart transplantation either as the therapy of choice or as a strategy by which to delay transplantation in younger patients.

Successful replacement of a HeartAssist 5 ventricular assist device with a HeartWare without removal of the original sewing/attachment rings: how to do it

Despite technological advances in a newer generation of ventricular assist devices (VAD), complications, such as pump thromboses, remain a significant cause of morbidity and indeed mortality in these patients. We present the case of a 34-year old patient who underwent HeartAssist 5 (HA5) implantation as a bridge to cardiac transplant. After an initial uneventful recovery, he developed a pump thrombosis that was refractory to medical treatment. We present the surgical technique used to exchange the HA5 with a HeartWare (HVAD), leaving the old inflow-sewing ring in situ.

Long-term mechanical circulatory support (destination therapy): on track to compete with heart transplantation?

OBJECTIVES

Average 2-year survival after cardiac transplantation is approximately 80%. The evolution and subsequent approval of larger pulsatile and, more recently, continuous flow mechanical circulatory support (MCS) technology for destination therapy (DT) offers the potential for triage of some patients awaiting cardiac transplantation to DT.

METHODS

The National Heart, Lung, and Blood Institute Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) is a national multi-institutional study of long-term MCS. Between June 2006 and December 2011, 127 pulsatile and 1160 continuous flow pumps (24% of total primary left ventricular assist devices [LVADs]) carried an initial strategy of DT therapy.

RESULTS

By multivariable analysis, risk factors (P < .05) for mortality after DT included older age, larger body mass index, history of cancer, history of cardiac surgery, INTERMACS level I (cardiogenic shock), dialysis, increased blood urea nitrogen, use of a pulsatile flow device, and use of a right ventricular assist device (RVAD). Among patients with a continuous flow LVAD who were not in cardiogenic shock, a particularly favorable survival was associated with no cancer, patients not in cardiogenic shock, and blood urea nitrogen less than 50 mg/dL, resulting in 1- and 2-year survivals of 88% and 80%.

CONCLUSIONS

(1) Evolution from pulsatile to continuous flow technology has dramatically improved 1- and 2-year survivals; (2) DT is not appropriate for patients with rapid hemodynamic deterioration or severe right ventricular failure; (3) important subsets of patients with continuous flow DT now enjoy survival that is competitive with heart transplantation out to about 2 years.