Use of an argatroban-based purge solution in a percutaneous ventricular assist device

Mechanical Circulatory Support Strategies in Takotsubo Syndrome with Cardiogenic Shock: A Systematic Review

BACKGROUND

Takotsubo syndrome is, by definition, a reversible form of acute heart failure. If cardiac output is severely reduced, Takotsubo syndrome can cause cardiogenic shock, and mechanical circulatory support can serve as a bridge to recovery. To date, there are no recommendations on when to use mechanical circulatory support and on which device is particularly effective in this context. Our aim was to determine the best treatment strategy.

METHODS

A systematic literature research and analysis of individual patient data was performed in MEDLINE/PubMed according to PRISMA guidelines. Our research considered original works published until 31 July 2023.

RESULTS

A total of 93 publications that met the inclusion criteria were identified, providing individual data from 124 patients. Of these, 62 (50%) were treated with veno-arterial extracorporeal life support (va-ECLS), and 44 (35.5%) received a microaxial left ventricular assist device (Impella). Eighteen patients received an Impella CP and twenty-one an Impella 2.5. An intra-aortic balloon pump (IABP) without other devices was used in only 13 patients (10.5%), while other devices (BiVAD or Tandem Heart) were used in 5 patients (4%). The median initial left ventricular ejection fraction was 20%, with no difference between the four device groups except for the IABP group, which was less affected by cardiac output failure (p = 0.015). The overall survival was 86.3%. Compared to the other groups, the time to cardiac recovery was shorter with Impella (p < 0.001).

CONCLUSIONS

Though the Impella treatment is new, our analysis may show a significant benefit of Impella compared to other MCS strategies for cardiogenic shock in Takotsubo syndrome.

Outcomes of systemic bivalirudin and sodium bicarbonate purge solution for Impella 5.5

BACKGROUND

Impella 5.5 (Abiomed; Danvers, MA) (IMP5) is a commonly used, surgically implanted, tMCS device that requires systemic anticoagulation and purge solution to avoid pump failure. To avoid heparin-induced thrombocytopenia (HIT) from unfractionated heparin (UFH) use, our program has explored the utility of bivalirudin (BIV) for systemic anticoagulation and sodium bicarbonate-dextrose purge solution (SBPS) in IMP5.5.

METHODS

This single center, retrospective study included 34 patients supported on IMP5.5 with BIV based AC and SBPS between December 1st 2020 to December 1st 2021.The efficacy and safety end points were incidence of development of HIT, Tissue Plasminogen Activator (tPA) use for suspected pump thrombosis, stroke, and device failure as well as clinically significant bleeding.

RESULTS

The median duration of IMP5.5 support was 9.8 days (IQR: 6-15). Most patients were bridged to HTX (58%) followed by recovery (27%) and LVAD implantation (15%). Patients were therapeutic on bivalirudin for 64% of their IMP5.5 support. One patient (2.9%) suffered from ischemic stroke and 26.5% (9) patients developed clinically significant bleeding. tPA was administered to 7(21%) patients. One patient in the entire cohort developed HIT.

CONCLUSIONS

Our experience supports the use of systemic BIV and SBPS as a method to avoid heparin exposure in a patient population predisposed to the development of HIT.

Incidence and severity of thrombocytopenia associated with use of intravascular microaxial ventricular assist devices for treatment of cardiogenic shock

INTRODUCTION

The use of temporary mechanical circulatory support (MCS) for patients with refractory cardiogenic shock has increased over the past decade. Impella devices (intravascular microaxial ventricular assist devices [VADs]) have become common MCS options but reportedly cause thrombocytopenia. Limited published data regarding the incidence or severity of microaxial VAD-associated thrombocytopenia exists.

OBJECTIVES

The goal of this study was to determine the incidence, timing, and severity of thrombocytopenia in a microaxial VAD population.

METHODS

A retrospective multicenter review of electronic medical records identified all patients implanted with microaxial VAD at three US academic teaching hospitals between June 2015 and August 2017. Patients were excluded for short-term procedural microaxial VAD use during percutaneous coronary intervention.

RESULTS

Sixty-four patients underwent microaxial VAD insertion (95% for left-sided support) during the observed time period. Support was in place for a median duration of 5.2 (interquartile range [IQR]: 2.4-10.0) days. Within 7 days postinsertion, 98.5% of patients developed thrombocytopenia (platelet count <150,000/μl) and 81.3% of patients experienced a >50% platelet decrease. Average platelet count nadir was 68,200/μl or 63.9% from baseline occurring on median day 3.8 (IQR: 2.4-5.4). Twenty-four patients (38.1%) were tested for heparin-induced thrombocytopenia by the heparin-dependent antibody (HDA) test. All HDAs were either negative or had serotonin release assay negative confirmation. Postdevice removal, platelet counts returned to baseline or >150,000/μl in 63% of patients by Day 5.

CONCLUSION

Microaxial VAD-associated thrombocytopenia is common. Practitioners should consider this when evaluating supported patients for other causes of thrombocytopenia. Platelet counts return to preimplantation levels within days of device removal.

What is known in pre-, peri-, and post-procedural anticoagulation in micro-axial flow pump protected percutaneous coronary intervention?

Interest in the use of percutaneous left ventricular assist devices (p-LVADs) for patients undergoing high-risk percutaneous coronary intervention (PCI) is growing rapidly. The Impella™ (Abiomed Inc.) is a catheter-based continuous micro-axial flow pump that preserves haemodynamic support during high-risk PCI. Anticoagulation is required to counteract the activation of the coagulation system by the patient’s procoagulant state and the foreign-body surface of the pump. Excessive anticoagulation and the effect of dual antiplatelet therapy (DAPT) increase the risk of bleeding. Inadequate anticoagulation leads to thrombus formation and device dysfunction. The precarious balance between bleeding and thrombosis in patients with p-LVAD support is often the primary reason that patients’ outcomes are jeopardized. In this chapter, we will discuss anticoagulation strategies and anticoagulant management in the setting of protected PCI. This includes anticoagulant therapy with unfractionated heparin, direct thrombin inhibitors, DAPT, purge blockage prevention by bicarbonate-based purge solution, and monitoring by activated clotting time, partial thromboplastin time, as well as anti-factor Xa levels. Here, we provide a standardized approach to the management of peri-interventional anticoagulation in patients undergoing protected PCI.

Evaluation of Thrombocytopenia in Patients Receiving Percutaneous Mechanical Circulatory Support With an Impella Device

Evaluate the time course of thrombocytopenia in patients with Impella devices (Abiomed, Danvers, MA).

Use of Sodium Bicarbonate Purge Solution in Impella Devices for Heparin-Induced Thrombocytopenia

Heparin purge solution is recommended to be used in Impella devices to prevent biomaterial buildup and subsequent device dysfunction. The use of sodium bicarbonate purge solution in an Impella device is described in two patients with heparin-induced thrombocytopenia (HIT). The first case details a patient with severe mitral regurgitation and cardiogenic shock who had an Impella CP placed who developed HIT. Heparin purge solution was replaced by sodium bicarbonate purge solution in addition to systemic direct thrombin inhibitor (DTI) initiation. There was no significant change in Impella purge pressure or flow over the 13 days of Impella use. The second case describes a patient who developed an acute myocardial infarction and subsequent cardiogenic shock for which an Impella CP was placed who also developed HIT. Heparin purge solution was replaced by sodium bicarbonate purge solution. There was no significant change in purge pressure, flow, or motor current spikes over 11 days of use. In conclusion, we describe the successful use of a novel sodium bicarbonate purge solution utilized in patients with HIT for Impella management alone and in combination with systemic direct thrombin inhibitor therapy. This resulted in no protein deposition in the device gaps or device dysfunction.

Heparin-Induced Thrombocytopenia under Mechanical Circulatory Support by Large Impella for Acute Cardiogenic Shock

Despite the critical feature of heparin-induced thrombocytopenia (HIT) for patients on mechanical circulatory support, reports on its incidence and outcome are still scarce. Thus, we report on clinical features of HIT in patients under Impella 5.0 or 5.5 (Abiomed Inc., Danvers, MA, USA) (Impella 5+) support for acute cardiogenic shock (CS) by focusing on observed thrombotic events. Between November 2018 and December 2020, a total of 56 consecutive patients were enrolled in a single-center retrospective study. A total of 21 patients (37.5%) were tested for HIT, and 6 (10.7%) proved positive for HIT at 10.5 ± 2.89 days after the first heparin administration during current admission. Interestingly, thrombocyte counts dropped under Impella support in all groups (all cases, no HIT test, and HIT negative group: p < 0.001, HIT-positive group: p = 0.001). All HIT-positive patients were switched from heparin to argatroban. HIT-associated thrombotic events were observed in two cases resulting in Impella dysfunction due to pump thrombosis (n = 1) and left ventricular (LV) thrombus formation (n = 1). Under large Impella support, the prevalence of HIT was relatively high. Further, thrombocytopenia does not deliver a high specificity in the setting of Impella 5+ support. Considering HIT manifestation, a routine HIT test may be considered to avoid critical thrombotic adverse events.

Optimizing anticoagulation for patients receiving Impella support

Anticoagulation of patients treated with the Impella percutaneous mechanical circulatory support (MCS) devices is complex and lacks consistency across centers, potentially increasing the risk of complications. In order to optimize safety and efficacy, an expert committee synthesized all available evidence evaluating anticoagulation for patients receiving Impella support in order to provide consensus recommendations for the management of anticoagulation with these devices. The evidence synthesis led to the creation of 42 recommendations to improve anticoagulation management related to the use of the Impella devices. Recommendations address purge solution management, intravenous anticoagulation, monitoring, evaluation and management of heparin-induced thrombocytopenia (HIT), and management during combination MCS support. The use of a heparinized, dextrose-containing purge solution is critical for optimal device function, and a bicarbonate-based purge solution may be an alternative in certain situations. Likewise, intravenous (ie, systemic) anticoagulation with heparin is often necessary, although evidence supporting the optimal assay and target range for monitoring the level of anticoagulation is generally lacking. Patients treated with an Impella MCS device may develop HIT, which is more difficult to evaluate and treat in this setting. Lastly, the use of Impella with extracorporeal membrane oxygenation or for biventricular support creates additional anticoagulation challenges.

Use of an argatroban systemic infusion and purge solution in a patient with a percutaneous ventricular assist device with suspected heparin-induced thrombocytopenia

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Thrombocytopenia can occur when using an Impella percutaneous ventricular assist device (pVAD), and heparin-induced thrombocytopenia (HIT) is often suspected. Data on heparin- and anticoagulant-free purge solutions in these devices are limited. Previous case reports have described argatroban-based purge solutions, both with and without systemic argatroban, at varying concentrations in patients with known or suspected HIT.

SUMMARY

A 33-year-old male was transferred to our institution and emergently initiated on life support with venoarterial extracorporeal membrane oxygenation (ECMO), an Impella pVAD, and continuous venovenous hemofiltration to receive an urgent aortic valve replacement. Over the next several days, the patient's platelet count declined with a nadir of 17 × 10 3/µL on hospital day 13. The patient's 4T score for probability of HIT was calculated as 4. All heparin products were discontinued on hospital day 15, and the patient was initiated on systemic infusion with argatroban 1,000 µg/mL at a rate of 0.2 µg/kg/min with a purge solution of argatroban 0.05 mg/mL. The systemic infusion remained at a rate of 0.2 µg/kg/min, and the total argatroban dose was, on average, less than 0.25 µg/kg/min. On hospital day 21, the patient was transferred to another institution.

CONCLUSION

Systemic infusion and a purge solution with argatroban were used in a patient with an Impella pVAD with multisystem organ dysfunction and suspected HIT. The patient achieved therapeutic activated partial thromboplastin times without adjustment of the systemic argatroban infusion and did not experience bleeding or thrombosis. Further studies concerning the safety and effectiveness of argatroban-based purge solutions in patients with pVADs are needed.

Anticoagulation with temporary Impella device in patients with heparin-induced thrombocytopenia: A case series

The Impella device is a percutaneous ventricular assist devices that requires administration of heparin via a continuous purge solution. Patients on Impella device support may experience hemolysis with accompanying thrombocytopenia generating suspicion for heparin-induced thrombocytopenia (HIT). However, data and recommendations for use of non-heparin anticoagulants with Impella device are lacking. Therefore, we performed a retrospective cohort analysis of patients requiring bivalirudin during Impella device support to describe the safety and efficacy of bivalirudin as an alternative anticoagulant during Impella device support. Nine patients were included in the evaluation which analyzed Impella device purge flow and purge pressure along with bivalirudin dosing requirements, incidence of thrombosis, and incidence of pump failure. All patients had a positive platelet factor-4 IgG ELISA test, and the serotonin release assay was positive in four patients. After initiation of bivalirudin, the median (15th, 85th percentile) nadir purge flow decreased by 76% (5%, 88%) and the median (15th, 85th percentile) peak purge pressure increased by 86% (21%, 143%). At the time of bivalirudin discontinuation, the median final purge flow and pressure were 2.4 mL/h (74% decrease) and 969 mmHg (89% increase), respectively. Zero patients experienced catastrophic pump failure. Adding low concentration bivalirudin to the purge solution along with systemic bivalirudin may be a reasonable approach.

Utilization of a Dextrose-Only Purge Solution for an LVAD in Patients With Suspected HIT: A Case Series

The Impella devices are percutaneous intravascular ventricular assist devices indicated for use in patients with cardiogenic shock that occurs following acute myocardial infarction (MI) or open heart surgery. These devices must be used with a purge solution that contains heparin per manufacturer recommendation, which will prevent blood from reaching the motor causing pump thrombosis and mechanical failure. We describe the utilization of a dextrose-only purge solution plus systemic argatroban in 2 patients with suspected heparin-induced thrombocytopenia (HIT). Each case describes a patient with suspected HIT following Impella placement for cardiogenic shock post-MI that had an increased bleeding risk. In each case, pharmacy monitored and adjusted the patients' argatroban, resulting in therapeutic anticoagulation without major bleeding or thrombotic events. These case reports demonstrate that use of a dextrose-only purge solution in the Impella device may be a safe and effective option when combined with systemic argatroban in patients with suspected or confirmed HIT who exhibit increased bleeding risk. Further research is needed to determine the optimal concentrations and duration of anticoagulation-free purge solution in these patients.

Use of Systemic Bivalirudin and an Anticoagulant-Free Purge Solution in a Percutaneous Left Ventricular Assist Device in a Patient With Heparin-Induced Thrombocytopenia

The use of systemic bivalirudin and an anticoagulant-free purge solution in a percutaneous left ventricular assist device (pVAD) is described in a patient with a history of heparin-induced thrombocytopenia (HIT). An 80-year-old man with a past medical history of severe aortic stenosis and HIT was transferred to our facility for cardiogenic shock. The patient was emergently taken to the cardiac catheterization laboratory for balloon valvuloplasty and Impella pVAD (Abiomed, Inc) implantation. Due to the history of HIT, bivalirudin was chosen as an alternative anticoagulant. The device representative suggested adding bivalirudin 20 mg/500 mL to the Impella purge solution. However, due to the negligible amount of bivalirudin this would provide in comparison to patient's systemic intravenous bivalirudin dose, we elected not to add bivalirudin to the purge solution. The patient remained on the Impella for 72 hours with intravenous bivalirudin without any evidence of pump thrombosis as evidenced by unchanging flows and stable purge pressures. Unfortunately, despite functional Impella pVAD support, care was withdrawn due to ongoing multi-organ failure. This patient case demonstrated the safe, effective, and practical use of an anticoagulant-free purge solution with systemic bivalirudin in a patient with 72 hours of Impella support.

Mechanical circulatory support for Takotsubo syndrome: a systematic review and meta-analysis

BACKGROUND

Cardiogenic shock occurs in 10%-15% of patients with Takotsubo syndrome (TS). For several reasons catecholamines, and especially inotropes, should be avoided in TS. Temporary mechanical circulatory support (MCS) appears attractive as bridge-to-recovery, but prospective studies are lacking. Here we analyze the available literature on MCS use in patients with TS.

METHODS AND RESULTS

PubMed/Medline was systematically screened until December 2019. 18 studies reporting pooled data of 5629 TS patients, of whom 227 had received MCS, were considered for a qualitative synthesis. 81 articles from 2003 through 2019 reporting individual data of 93 MCS cases were included in a meta-analysis. Median age was 57 (IQR: 43-68) years, 83.9% were women, and a physical trigger could be identified in 74.1% of cases. Median left ventricular ejection fraction (LVEF) before MCS was 20% (IQR: 15-25) and comparable between groups defined by MCS device. An apical TS type was present in 76.1% of cases. The overall number of publications on MCS for TS increased over time, as did those using veno-arterial extracorporeal membrane oxygenation (V-A ECMO) and Impella, while those using intra-aortic balloon pump declined. MCS-related complications were not regularly reported. Median time on MCS was 3 (IQR: 2-7) days, with an overall survival of 94.6%.

CONCLUSIONS

MCS for TS-related shock is increasingly reported, with a growing use of V-A ECMO and Impella. Currently available clinical data support this approach. Prospective studies are needed to evaluate safety and efficacy of different devices as well as timing of MCS in this special patient population.

Management of Anticoagulation with Impella® Percutaneous Ventricular Assist Devices and Review of New Literature

Cardiogenic shock is a life-threatening condition that may occur secondary to a variety of cardiac conditions, and may require temporary support with percutaneous ventricular devices like the Impella®. Anticoagulation in patients with Impella® devices can often be complicated due to unpredictable purge flow rates, pre-existing coagulopathy, or heparin allergies. The purpose of this article is to discuss the various options for anticoagulation in the setting of Impella®. The article will also describe recent updates (2014-current) in literature surrounding anticoagulation therapy for Impella® devices. At total of 228 articles were initially obtained through the PubMed search, with inclusion of 6 articles. A total of 51 patients had data in the six studies that were included in the review. Heparin for anticoagulation in the purge solution, at two different dextrose concentrations (5% and 20%), was associated with similar therapeutic activated partial thromboplastin time rates, thrombotic and bleeding events. One case series described the use of argatroban in the purge solution for anticoagulation in two patients with suspected heparin-induced thrombocytopenia, without bleeding or thrombotic complications. Pump thrombosis was not reported in any of the six studies. Anticoagulation in the setting of mechanical circulatory support devices is a challenging aspect of critical care. Institutions should have set protocols that clearly define the options for anticoagulation. Future studies that look at longer durations of support and possible operation of the Impella® device with a heparin-free purge solution are needed.

Therapeutic Anticoagulation With an Ultra-Low Concentration Argatroban-Based Purge Solution for Percutaneous Ventricular Assist Device in Patient With Heparin-Induced Thrombocytopenia

Purpose/Background: Percutaneous left ventricular assist devices (pVADs) require a continuous purge solution containing heparin to prevent pump thrombosis and device failure. Data regarding alternative options in patients who have suspected heparin-induced thrombocytopenia (HIT) are limited. Methods: In this report, we describe a 68-year-old white man with cardiogenic shock with an Impella CP device managed with a low concentration argatroban-based purge solution secondary to a suspected diagnosis of HIT. Results: The purge solution was initiated as argatroban in dextrose 10% at a concentration of 0.12 mg/mL and was subsequently decreased twice to 0.06 and 0.015 mg/mL based on the patient's clinical course. Conclusions: This case report describes the safe and effective use of argatroban purge solution necessary for anticoagulation although further studies are needed to confirm these findings.

Clinical scenarios for use of transvalvular microaxial pumps in acute heart failure and cardiogenic shock - A European experienced users working group opinion

For patients with myocardial infarct-related cardiogenic shock (CS), urgent percutaneous coronary intervention is the recommended treatment strategy to limit cardiac and systemic ischemia. However, a specific therapeutic intervention is often missing in non-ischemic CS cases. Though drug treatment with inotropes and/or vasopressors may be required to stabilize the patient initially, their ongoing use is associated with excess mortality. Coronary intervention in unstable patients often leads to further hemodynamic compromise either during or shortly after revascularization. Support devices like the intra-aortic balloon pump failed to improve clinical outcomes in infarct-related CS. Currently, more powerful and active hemodynamic support devices unloading the left ventricle such as transvalvular microaxial pumps are available and are being increasingly used. However, as for other devices large randomized trials are not yet available, and device use is based on registry data and expert consensus. In this article, a multidisciplinary group of experienced users of transvalvular microaxial pumps outlines the pathophysiological background on hemodynamic changes in CS, the available mechanical support devices, and current guideline recommendations. Furthermore, different hemodynamic situations in several case-based scenarios are used to illustrate candidate settings and to provide the theoretic and scientific rationale for left-ventricular unloading in these scenarios. Finally, organization of shock networks, monitoring, weaning, and typical complications and their prevention are discussed.

Survey of Anticoagulation Practices with the Impella Percutaneous Ventricular Assist Device at High-Volume Centers

Objectives

To characterize anticoagulation practices with the Impella percutaneous ventricular assist device (pVAD).

Background

Managing anticoagulation in patients being supported by the Impella pVAD is made challenging by several unique features of the device. These include the release of a dextrose-based purge solution containing unfractionated heparin (UFH), the need to concurrently administer systemic anticoagulation with intravenous UFH, and the lack of an alternative strategy in patients with contraindications to UFH.

Methods

To characterize anticoagulation practices with the Impella pVAD, we conducted a survey of centers in the United States performing a high volume of Impella cases, which we defined as > 1 per month. Centers were contacted via email or phone and individuals who agreed to participate were provided with a link to complete the survey online. The primary measures of interest were variations in practice across centers and variations from the manufacturer's recommendations.

Results

Practices varied considerably among respondents (65 of 182 centers, or 35.7%) and often diverged from manufacturer recommendations. Approximately half of centers (52.4%) reported using a UFH concentration of 50 units/mL in the purge solution, whereas most of the remaining centers (41.3%) reported using lower concentrations. Strategies for the initiation and adjustment of systemic therapy also varied, as did practices for routinely monitoring for hemolysis. Nearly one-fifth of centers (16.7%) had not developed an alternative strategy for the purge solution in patients with contraindications to UFH. Most centers (58.4%) reported using argatroban or bivalirudin in this scenario, a strategy that diverges from the manufacturer's recommendations.

Conclusions

Given these findings, studies to determine a systematic approach to anticoagulation with the Impella device are warranted.

Assistance ventriculaire gauche par Impella® : indications, gestion et complications

L’assistance monoventriculaire Impella® est une assistance microaxiale non pulsatile dépourvue de fonction d’oxygénation et/ou de décarboxylation. Sur le principe de la vis sans fin d’Archimède, elle aspire le sang dans le ventricule gauche pour le réinjecter dans la racine de l’aorte en regard des ostia coronaires. Selon le modèle utilisé, le débit d’assistance antérograde ainsi généré varie de 2,5 à 5 l/min. De par son mode de fonctionnement, l’assistance Impella® permet une décharge ventriculaire efficace. Ses indications sont l’angioplastie coronaire à haut risque et le choc cardiogénique réfractaire aux agents cardiovasoactifs. Chez le patient assisté par une extracorporeal life support (ECLS), la pompe Impella® permet de limiter le risque de surcharge ventriculaire. Chez le patient exclusivement assisté par Impella® soit d’emblée ou après une association avec l’ECLS, la voie d’abord axillaire permet sa réhabilitation active y compris la déambulation et l’activité physique. Elle se révèle alors une mise à l’épreuve cliniquement pertinente du ventricule droit en vue d’une assistance de longue durée de type left ventricular assist device.

Anticoagulation of a Percutaneous Left Ventricular Assist Device Using a Low-Dose Heparin Purge Solution Protocol: A Case Series

Background

Impella CP® is a percutaneous left ventricular assist device that requires a heparin–dextrose purge solution. The manufacturer recommends heparin 50 units/mL, but supratherapeutic anticoagulation has been observed with this concentration.

Objective

The purpose of this evaluation was to observe the efficacy and safety of a low-dose heparin-based purge solution (25 units/mL in dextrose 20%). The primary outcome evaluated percentage of activated clotting times (ACTs) below therapeutic range. Secondary objectives included evaluating the incidence of device thrombosis and rate of heparin-induced thrombocytopenia (HIT). Platelet trends were characterized.

Methods

A single-site retrospective review was conducted for all adults with the Impella CP from January 2015 to December 2017.

Results

A total of 18 patients were included. The percentage of ACT readings within goal of 160 to 200 seconds was 49%, and 38% of readings were subtherapeutic. Per BARC bleeding criteria, 22% (n = 4) patients experienced class IIIa bleeding and 39% (n = 7) experienced class II bleeding. Though 4 (22%) patients were tested for HIT, no patients were positive. Patients showed universal reductions in platelet counts.

Conclusions

The use of a low-dose anticoagulation protocol of heparin 25 units/mL in dextrose 20% as needed warrants further evaluation.

Adult and pediatric mechanical circulation: a guide for the hematologist

Mechanical circulatory support (MCS) is the overarching term that encompasses the temporary and durable devices used in patients with severe heart failure. MCS disturbs the hematologic and coagulation system, leading to platelet activation, activation of the contact pathway of coagulation, and acquired von Willebrand syndrome. Ischemic stroke and major hemorrhage occur in up to 30% of patients. Hematologists are an essential part of the MCS team because they understand the delicate balance between bleeding and clotting and alteration of hemostasis with antithrombotic therapy. However, prior to this important collaborative role, learning the terminology used in the field and types of MCS devices allows improved communication with the MCS team and best patient care. Understanding which antithromobotic therapies are used at baseline is also required to provide recommendations if hemorrhage or thrombosis occurs. Additional challenging consultations in MCS patients include the influence of thrombophilia on the risk for thrombosis and management of heparin-induced thrombocytopenia. This narrative review will provide a foundation to understand MCS devices how to prevent, diagnose, and manage MCS thrombosis for the practicing hematologist.

Bleeding Risks in Patients on Percutaneous Ventricular Assist Devices Receiving Two Different Dextrose Concentrations of Heparinized Purge Solution: A Case Series

BACKGROUND

The Impella manufacturer has changed its recommendation for the diluent of the heparinized purge solution from 20% dextrose (D20) to 5% dextrose (D5). This reduced viscosity may result in increased purge solution infusion rates and unfractionated heparin (UFH) exposure. Increased UFH exposure could potentially cause increased bleeding events and may necessitate reduction in UFH concentration in the purge solution. Our objective was to evaluate anticoagulation for patients on Impella pumps receiving heparinized purge solution with D20 or D5 diluents.

METHODS

This retrospective cohort analysis evaluated patients requiring Impella support outside of the cardiac catheterization lab. The primary outcome evaluated the number of patients with at least one supratherapeutic activated partial thromboplastin time (aPTT) while receiving heparinized purge solution alone without systemic UFH. Secondary outcomes included heparin concentration changes made to the purge solution, bleeding, and thrombotic events.

RESULTS

Twelve patients received Impella support for an average of 37 hours (range, 10.8-89.6). Four patients received D20 and 8 patients received D5 purge solution. Five patients had at least one supratherapeutic aPTT while receiving heparinized purge solution alone without additional systemic UFH. All 5 patients were in the D5 group. Of these 5 patients, 3 required purge heparin concentration decreases and 3 had bleeding events. No patients had pump thrombosis.

CONCLUSION

D5 purge solution with heparin 50 units/mL may increase the risk of supratherapeutic aPTTs, leading to increased bleeding. Decreasing heparin to 25 units/mL as a standard in purge solution may decrease these risks; however, protection against thrombosis remains unknown.

Anticoagulation of Percutaneous Ventricular Assist Device Using Argatroban-Based Purge Solution: A Case Series

Impella devices are percutaneously inserted ventricular assist devices which require a continuous purge solution that contains heparin to prevent pump thrombosis and device failure. We describe 2 patients with heparin-induced thrombocytopenia (HIT) supported with an Impella device utilizing an argatroban-based purge solution. Case 1 involved an 83-year-old female with biventricular failure which resulted in right ventricle Impella support. The purge solution was changed to include argatroban due to concern of device clotting in the setting of HIT. Case 2 involved a 55-year-old male with worsening cardiogenic shock which resulted in left ventricle Impella support. Due to decreased purge flow rates and concerns for clotting, argatroban was added to the purge solution. Both patients' total argatroban regimens were monitored and adjusted by pharmacy, resulting in therapeutic anticoagulation without any major bleeding or thrombotic events. Subsequently, a protocol was designed and implemented. These case reports appear to demonstrate the safe and effective use of argatroban purge solutions for the necessary anticoagulation with an Impella device. Further studies are needed to confirm these results and determine the optimal dosing regimen.