Optimizing anticoagulation for patients receiving Impella support

Safety and Effectiveness of an Anti-Xa-based Unfractionated Heparin Protocol for Impella Percutaneous Ventricular Assist Devices

Background: Impella devices are used for mechanical circulatory support in patients with cardiogenic shock or those undergoing high-risk percutaneous coronary intervention (PCI). Anticoagulation protocols in this population are not well established and are complicated by concomitant use of purge solutions containing unfractionated heparin (UFH) and intravenous UFH continuous infusion (CI) for systemic anticoagulation. Objectives: To evaluate thrombotic and bleeding complications when using a novel UFH protocol with a reduced initial UFH CI dose of 6 units/kg/hour targeting an anti-Xa goal of 0.3 to 0.5 units/mL in patients receiving Impella support. Methods: This single-center, retrospective study included 41 patients on Impella support who received an UFH purge solution and/or an IV UFH infusion. The primary outcome was overall composite bleeding. Secondary outcomes included thrombotic events and systemic UFH exposure. An exploratory analysis was performed to identify risk factors for bleeding. Results: Anti-Xa values were in therapeutic range 46% of the time while on support (interquartile range 16.6%-75%), with a median IV UFH dose of 6 units/kg/hour. The overall bleeding rate was 29.2%, with 6 minor bleeds and 2 major bleeds with no fatal bleeding or intracranial hemorrhage. Rate of overall thrombosis was 4.9%, including 1 ischemic stroke and 1 occurrence of limb ischemia. Conclusion: Use of a modified UFH protocol to target an anti-Xa goal of 0.3 to 0.5 units/mL resulted in bleeding and thrombotic event rates similar to previous literature. This protocol utilizing an initial rate of 6 units/kg/hour may be a useful approach to achieve therapeutic anticoagulation while accounting for UFH exposure from the purge solution and minimizing need for frequent calculations.

Mechanical Circulatory Support in Cardiogenic Shock: Uses in the Emergency Setting

Cardiogenic shock is a lethal condition with significant morbidity, characterized by myocardial insults leading to low cardiac output and ensuing systemic hypoperfusion. While mortality rates remain high, we have improved upon our recognition and definition of cardiogenic shock, now with an emphasis on defining stages of shock to help guide effective treatment strategies with either pharmacologic or mechanical circulatory support. In this review, the authors summarize these stages as well as discuss indications, function, selection, and troubleshooting of the various temporary mechanical circulatory support devices.

Perioperative Left Ventricular Assist Device Use in Patients With Reduced Ejection Fraction Reduces Cardiac Surgery-Associated Acute Kidney Injury

Background Cardiac surgery may precipitate acute kidney injury (AKI), particularly in patients with poor baseline cardiac function. This is thought to be due to intraoperative renal hypoperfusion, which results in increased morbidity and mortality. This study evaluated the perioperative use of the Impella LD (Abiomed, Danvers, MA) left ventricular assist device (LVAD) in the prevention of postoperative AKI in patients with reduced left ventricular ejection fraction (LVEF) undergoing cardiac surgery. Methods A retrospective analysis was performed at Northwest Medical Center, Tucson, AZ, USA, on patients undergoing valve surgery, coronary artery bypass grafting (CABG), or both by a single surgeon. Those with preoperative LVEF ≤35% and preoperative serum creatinine ≥1 mg/dL were included and segregated based on intraoperative LVAD implantation. Postoperative renal function was assessed using serum creatinine levels and KDIGO (Kidney Disease Improving Global Outcomes) criteria to define AKI. Results Twenty-three patients were enrolled. There were no significant differences in age, demographics, baseline characteristics, or comorbidities between the treatment (n = 12) and the control group (n = 11). In the treatment group, 8% developed AKI by POD#7, while 64% of controls did. The treatment group had a significantly lower mean creatinine change from POD#0-7 (0.07 vs. 0.59, p = 0.02). However, there was no significant difference between groups in the mean creatinine change from baseline to discharge (0.46 vs. 0.42, p = 0.47). Conclusions Our study suggests that intraoperative Impella implantation may reduce the incidence of early postoperative AKI. LVAD implantation is an approach to increase and ensure adequate end-organ (renal) perfusion and can improve postoperative recovery without dialysis requirements. Additional studies are required to understand its protective effects during the perioperative period fully.

A case series analysis of bicarbonate-based purge solution administration via Impella ventricular assist device

PURPOSE

The Impella device historically required a heparin-based purge solution to reduce the risk of biomaterial deposition to maintain pump function. In April 2022, the Food and Drug Administration approved utilization of bicarbonate-based purge solutions (BBPS) as an alternative to heparin for patients who are intolerant to heparin or in whom heparin is contraindicated. The purpose of this case series is to report patient outcomes of Impella support with BBPS use at our institution.

SUMMARY

Eighteen patients who received BBPS via the Impella CP or Impella 5.5 device were included in our review. Patients were included if they had BBPS administration for greater than 24 hours. All patients were followed for 72 hours after cessation of BBPS. Indications for BBPS were coagulopathy (n = 5, 28%), suspected HIT (n = 2, 11%), confirmed HIT (n = 1, 6%), and major bleeding (n = 10, 56%). Three patients (17%) experienced an Impella complication while on BBPS. One patient required pump exchange, one required removal of the Impella device, and one received alteplase for suspected purge block. Of these, two patients experienced complications greater than 21 days into BBPS therapy.

CONCLUSION

This case series adds to the literature describing clinical outcomes for patients on Impella support with BBPS. While BBPS offers a viable option for the management of patients on Impella devices who are unable to tolerate heparin-based purge solutions, further data is needed to determine the longevity of the Impella device with BBPS to minimize risk of Impella complications.

Facility-based approach for the management of acute ST segment elevation myocardial infarction with cardiogenic shock in a rural medical centre: the Durango model

INTRODUCTION

Cardiogenic shock (CS) complicates 5%-15% of cases of acute myocardial infarction (AMI) with inpatient mortality greater than 40%. The implementation of standardised protocols may improve clinical outcomes in patients with AMI-CS.

METHODS AND ANALYSIS

The Durango model is a prospective single-centre registry designed to enable early identification of patients with STEMI-CS to facilitate primary reperfusion therapy with a shock team management algorithm in a rural level II heart attack centre. This prospective registry includes all patients >18 years of age presenting with STEMI with or without CS beginning on 1 February 2023. The primary outcome measures are adherence to model-based documentation of SCAI shock Classification prehospital and in the ED with appropriate STEMI shock alert for AMI and stages C, D, E shock; use of mechanical circulatory support Pre-PCI and door to support time <90 min.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board with a waiver of informed consent. The findings will be submitted for publication in a peer-review open access journal on completion of the study.

CONCLUSIONS

The Durango model will demonstrate that the implementation of a STEMI shock team can be feasible in a rural medical centre through comprehensive education of a diverse group providers with different levels of experience, continuous model/device proficiency training and performance feedback.

Current and future options for adult biventricular assistance: a review of literature

In cardiogenic shock various short-term mechanical assistances may be employed, including an Extra Corporeal Membrane Oxygenator and other non-dischargeable devices. Once hemodynamic stabilization is achieved and the patient evolves towards a persisting biventricular dysfunction or an underlying long-standing end-stage disease is present, aside from Orthotopic Heart Transplantation, a limited number of long-term therapeutic options may be offered. So far, only the Syncardia Total Artificial Heart and the Berlin Heart EXCOR (which is not approved for adult use in the United States unlike in Europe) are available for extensive implantation. In addition to this, the strategy providing two continuous-flow Left Ventricular Assist Devices is still off-label despite its widespread use. Nevertheless, every solution ensures at best a 70% survival rate (reflecting both the severity of the condition and the limits of mechanical support) with patients suffering from heavy complications and a poor quality of life. The aim of the present paper is to summarize the features, implantation techniques, and results of current devices used for adult Biventricular Mechanical Circulatory Support, as well as a glance to future options.

Sodium bicarbonate as a local adjunctive agent for limiting platelet activation, aggregation, and adhesion within cardiovascular therapeutic devices

Cardiovascular therapeutic devices (CTDs) remain limited by thrombotic adverse events. Current antithrombotic agents limit thrombosis partially, often adding to bleeding. The Impella® blood pump utilizes heparin in 5% dextrose (D5W) as an internal purge to limit thrombosis. While effective, exogenous heparin often complicates overall anticoagulation management, increasing bleeding tendency. Recent clinical studies suggest sodium bicarbonate (bicarb) may be an effective alternative to heparin for local anti-thrombosis. We examined the effect of sodium bicarbonate on human platelet morphology and function to better understand its translational utility. Human platelets were incubated (60:40) with D5W + 25 mEq/L, 50 mEq/L, or 100 mEq/L sodium bicarbonate versus D5W or D5W + Heparin 50 U/mL as controls. pH of platelet-bicarbonate solutions mixtures was measured. Platelet morphology was examined via transmission electron microscopy; activation assessed via P-selectin expression, phosphatidylserine exposure and thrombin generation; and aggregation with TRAP-6, calcium ionophore, ADP and collagen quantified; adhesion to glass measured via fluorescence microscopy. Sodium bicarbonate did not alter platelet morphology but did significantly inhibit activation, aggregation, and adhesion. Phosphatidylserine exposure and thrombin generation were both reduced in a concentration-dependent manner-between 26.6 ± 8.2% (p = 0.01) and 70.7 ± 5.6% (p < 0.0001); and 14.0 ± 6.2% (p = 0.15) and 41.7 ± 6.8% (p = 0.03), respectively, compared to D5W control. Platelet aggregation via all agonists was also reduced, particularly at higher concentrations of bicarb. Platelet adhesion to glass was similarly reduced, between 0.04 ± 0.03% (p = 0.61) and 0.11 ± 0.04% (p = 0.05). Sodium bicarbonate has direct, local, dose-dependent effects limiting platelet activation and adhesion. Our results highlight the potential utility of sodium bicarbonate as a locally acting agent to limit device thrombosis.

Analysis of Bicarbonate-Based Purge Solution in Patients With Cardiogenic Shock Supported Via Impella Ventricular Assist Device

BACKGROUND

The Impella device is a continuous axial flow pump which provides hemodynamic support by expelling blood into the aorta. The manufacturer recommends using dextrose-based heparin containing solutions as the default purge. As an alternative to anticoagulant solutions, a bicarbonate-based purge solution has been proposed with limited data substantiating adequate protection and durability.

OBJECTIVE

To assess the impact of a bicarbonate-based purge solution on Impella pump thrombosis and bleeding outcomes.

METHODS

Single-center, retrospective study of cardiogenic shock patients who received an Impella between December 2020 through September 2021. Patients were evaluated based on whether they received bicarbonate-based purge solutions or remained on heparin-based purge solutions. The primary outcome was the rate of Impella pump thrombosis, defined as multiple purge pressures greater than 800 mm Hg. Secondary outcomes included incidence of bleeding defined as a drop in Hgb of at least 2 g/dL along with use of blood products and supratherapeutic anticoagulation defined as an aPTT of greater than 70 seconds.

RESULTS

Forty-three patients received bicarbonate-based purge solutions and 49 controls received heparin. The incidence of purge thrombosis by purge pressure threshold was similar between the two groups (16.3% vs 12.2%, P = 0.58). The rate of bleeding was lower with bicarbonate-based purge (27.9% vs 65.3%, P < 0.05) driven by a drop in Hgb of more than 2 g/dL. The rate of supratherapeutic anticoagulation was higher in the heparin arm (65.3% vs 27.9%, P < 0.05).

CONCLUSION AND RELEVANCE

Nonanticoagulant purge alternatives offer the potential to reduce bleeding complications and laboratory monitoring burden while maintaining durability.

[The Role of the Percutaneous Impella Pump in Anesthesia and Intensive Care]

The use of temporary mechanical circulatory support (tMCS) devices and in particular the increasing use of the Impella device family has gained significant interest over the last two decades. Nowadays, its use plays a well-established key role in both the treatment of cardiogenic shock, and as a preventive and protective therapeutic option during high-risk procedures in both cardiac surgery and cardiology, such as complex percutaneous interventions (protected PCI). Thus, it is not surprising that the Impella device is more and more present in the perioperative setting and especially in patients on intensive care units. Despite the numerous advantages such as cardiac resting and hemodynamic stabilization, potential adverse events exist, which may lead to severe, but preventable complications, so that adequate education, early recognition of such events and a subsequent adequate management are crucial in patients with tMCS. This article provides an overview especially for anesthesiologists and intensivists focusing on technical basics, indications and contraindications for its use with special focus on the intra- and postoperative management. Furthermore, troubleshooting for most common complications for patients on Impella support is provided.

Tissue plasminogen activator for axillary Impella 5.0 with heparin-induced thrombocytopenia as a treatment of choice for acute Impella thrombosis: a case report

Background

Patients with cardiogenic shock requiring temporary support with percutaneous ventricular assist device, such as Impella (Abiomed, Inc.), can develop heparin-induced thrombocytopenia (HIT) which requires use of alternative purge solution anticoagulation. There are limited recommendations on use of anticoagulation other than standard Unfractionated Heparin in 5% dextrose solution.

Case summary

This case describes 69-year-old female who presented with symptoms of decompensated systolic heart failure and was found to be in cardiogenic shock and despite use of inotropes and vasopressors maintained low systolic blood pressure and low mixed venous oxygen saturation which lead to use of axillary Impella 5.0 (Abiomed, Inc.) who developed HIT. Purge solution anticoagulation was switched to Argatroban, but due to increased motor pressures, tissue plasminogen activator (tPA) was successfully used to maintain proper motor pressures. Ultimately, patient was transferred to an outside facility for a transplant evaluation.

Discussion

This case demonstrates successful and safe use of tPA as an alternative purge solution although more data needed to support this finding.

Anticoagulation practices and complications associated with Impella® support at an advanced cardiac center in the Middle East gulf region

Anticoagulation during Impella® support is a challenge due to its complications and inconsistent practice across the globe. This observational, retrospective chart review included all patients with Impella® support at our advanced cardiac center at a quaternary care hospital in the Middle East gulf region. The study was conducted over six years (2016-2022), a time period during which manufacturer recommendations for purge solution, anticoagulation protocols as well as Impella® place in therapy and utilization were all evolving. We aimed to evaluate the efficacy of different anticoagulation practices and association with complications and outcomes. Forty-one patients underwent Impella® during the study period, including 25 patients with support for more than 12 h, and are the focus of our analysis. Cardiogenic shock (n = 25, 60.9%) was the primary indication for Impella®, followed by facilitating high-risk PCI (n = 15, 36.7%) and left ventricular afterload reduction in patients undergoing veno-arterial extracorporeal membrane oxygenation (n = 1, 2.4%). Our overall Impella® usage evolved over the years from a primary use to facilitate a high-risk PCI to the recent more common use of LV unloading in cardiogenic shock. No patients experienced device malfunction and the incidence of other complications including ischemic stroke and bleeding were comparable to those reported in the literature (12.2% and 24% respectively). The 30-day all-cause mortality of 41 patients was 53.6%. In line with the evolving recommendations and evidence, we observed an underutilization of non-heparin-based purge solutions and inconsistent management of anticoagulation in the setting of both Impella® and VA ECMO which necessitates more education and protocols.

Switch to a bicarbonate-based Impella CP™ purge solution in a patient with haemothorax: a case report

Background

Percutaneous mechanical circulatory support (pMCS) by an Impella™ device implies the initiation of systemic anticoagulation to prevent systemic thrombotic complications and a purge fluid to prevent device blockage. Traditionally, unfractionated heparin (UFH) was used for both. In April 2022, the use of bicarbonate-based purge solution (BBPS) as an alternative to UFH in dextrose solution was approved by the Food and Drug Administration in case of contraindications for UFH.

Case summary

We present the case of a 73-year-old female that was admitted to the cardiac intensive care unit with cardiogenic shock, requiring upgrade with pMCS by an axillary Impella CP™. When she developed a severe haemothorax, all UFH was stopped and the purge was switched to BBPS-dextrose solution without increase in purge pressures nor development of haemolysis. The bleeding stagnated and the patient could be weaned from the Impella™ after 2 days.

Discussion

Here, we present the first case report of the switch to BBPS in an Impella CP™ supported patient with major bleeding since the FDA approval in April 2022. The switch to BBSP in addition with the administration of platelets and protamine resulted in cessation of the bleeding in this case.

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.

Position Statement on Vascular Access Safety for Percutaneous Devices in AMI Complicated by Cardiogenic Shock

In the United States, the frequency of using percutaneous mechanical circulatory support devices for acute myocardial infarction complicated by cardiogenic shock is increasing. These devices require large-bore vascular access to provide left, right, or biventricular cardiac support, frequently under urgent/emergent circumstances. Significant technical and logistical variability exists in device insertion, care, and removal in the cardiac catheterization laboratory and in the cardiac intensive care unit. This variability in practice may contribute to adverse outcomes observed in centers that receive patients with cardiogenic shock, who are at higher risk for circulatory insufficiency, venous stasis, bleeding, and arterial hypoperfusion. In this position statement, we aim to: 1) describe the public health impact of bleeding and vascular complications in cardiogenic shock; 2) highlight knowledge gaps for vascular safety and provide a roadmap for a regulatory perspective necessary for advancing the field; 3) propose a minimum core set of process elements, or "vascular safety bundle"; and 4) develop a possible study design for a pragmatic trial platform to evaluate which structured approach to vascular access drives most benefit and prevents vascular and bleeding complications in practice.