Pharmacologic Considerations in the Management of Patients Receiving Left Ventricular Percutaneous Mechanical Circulatory Support

Heparin dosing in patients with Impella-supported cardiogenic shock

BACKGROUND

Impella™ is increasingly used in cardiogenic shock. However, thromboembolic and bleeding events are frequent during percutaneous mechanical circulatory support (pMCS).

OBJECTIVE

Therefore, we aimed to explore the optimal anticoagulation regime for pMCS to prevent thromboembolism and bleedings.

METHODS

This hypothesis-generating multi-center cohort study investigated 170 patients with left-Impella™ support. We (A) compared bleeding/thrombotic events in two centers with therapeutic range (TR-aPTT) activated partial thromboplastin time (60-80s) and (B) compared events of these centers with one center with intermediate range aPTT (40-60s).

RESULTS

After matching, there were no differences in patients' characteristics. In centers aiming at TR-aPTT, major bleeding was numerically lower with aPTT <60s within 48 h of left-Impella™ support, versus patients that achieved the aimed aPTT of ≥60s [aPTT ≥60s: 22 (37.3%) vs. aPTT<60s 14 (23.7%); Hazard ratio [HR], 0.62 (95%) CI, 0.28-1.38; p = 0.234]. Major cardiovascular and cerebrovascular adverse events (MACCE) did not differ between groups. In comparison of centers, TR-aPTT strategy showed higher major bleeding rates [TR: 8 (47.1%) vs. intermediate range: 1 (5.9%); HR, 0.06 (95%) CI, 0.01-0.45; p = 0.006]. MACCE were lower in the intermediate range aPTT group as well [TR 12 (70.6%) vs. intermediate range 5 (29.4%) HR, 0.32 (95%) CI, 0.11-0.92; p = 0.034].

CONCLUSION

This pilot analysis showed that lowering UFH-targets in left-Impella™ supported CS patients seems to be a safe and promising strategy for reducing major bleedings without increasing MACCE. This needs to be validated in larger, randomized clinical trials.

The Successful Rotor Wing Transport of 2 Patients Requiring Biventricular Impella Support: A Case Series and Review

Despite many advances in care, the mortality rate for cardiogenic shock remains high. Because the medical management of patients with cardiogenic shock is limited, many patients often require mechanical circulatory support. As such, cardiogenic shock patients requiring percutaneous ventricular support devices such as the Impella (Abiomed, Danvers, MA) may be encountered by critical care transport crews with increasing frequency. Recently, biventricular Impella support has been described as a mechanical support strategy for biventricular failure. This case series describes the successful rotor wing transport of 2 patients with severe cardiogenic shock requiring biventricular Impella support and presents a review of Impella RP (Abiomed) and biventricular Impella support devices for the critical care transport medicine clinician.

Perioperative Anticoagulation Management

Management of anticoagulation in individuals undergoing operative procedures is a complex situation. Each case should be assessed individually with proper risk assessment, monitoring, and plan for perioperative and postoperative anticoagulation. Clinical evidence for the management of these patients is relatively scarce, and clinicians are often assessing each individual case with minimal guidance. This review provides nurses with a summary of available literature on the assessment, laboratory monitoring, timing of adjusting anticoagulation, and bridging prior to procedures. In addition to general perioperative anticoagulation management, this review discusses perioperative management in special populations and provides a summary on principles when anticoagulation should be resumed following a procedure.

A Multidisciplinary Educational Approach to Anticoagulation Management for a Percutaneous Endovascular Mechanical Circulatory Support Device

Background

Anticoagulation (AC) management of the Impella varies considerably among treatment centers. Published data regarding the management of complications including heparin-induced thrombocytopenia, bleeding and thrombosis are limited.

Objective

A multidisciplinary team was assembled to 1) identify baseline knowledge of nurses and pharmacists involved in Impella anticoagulation management; 2) develop an educational tool specific to Impella anticoagulation; 3) reassess knowledge following implementation of the tool.

Methods

A team consisting of pharmacists, nurses and a physician developed surveys that were subsequently distributed to 28 nurses and 17 pharmacists. Survey questions measured knowledge in 4 areas of anticoagulation management: product selection, administration, monitoring and therapeutic recommendation. A pocket card containing flow diagrams for Impella anticoagulation management was developed. Following distribution of the card and education on its application, surveys were redistributed to measure the change in knowledge.

Results

The frequency (%) of correct answers for all survey questions for both pharmacists and nurses significantly increased from 38% to 84% (p < 0.00001) and 63% to 93% (p < 0.00001), respectively. Substantial increases in the frequency of correct answers in the majority of question categories were observed for both pharmacists and nurses postintervention.

Conclusion and Relevance

Using a multidisciplinary approach, an institution-specific pocket card addressing the complexities of Impella anticoagulation was developed. Following dissemination of the card and education on its application, improved knowledge across the scope of Impella anticoagulation management was observed in both pharmacists and nurses.

Impella in Transport: Physiology, Mechanics, Complications, and Transport Considerations

Cardiogenic shock (CS) represents a spectrum of hemodynamic deficits in which the cardiac output is insufficient to provide adequate tissue perfusion. The Impella (Abiomed Inc, Danvers, MA) device, a contemporary percutaneous ventricular support, is most often indicated for classic, deteriorating, and extremis Society for Coronary Angiography and Intervention stages of CS, which describe CS that is not responsive to optimal medical management and conventional treatment measures. Impella devices are an evolving field of mechanical support that is used with increasing frequency. Critical care transport medicine crews are required to transport patient support by the Impella device with increasing frequency. It is important that critical care transport medicine crews are familiar with the Impella device and are able to troubleshoot complications that may arise in the transport environment. This article reviews many aspects of the Impella device critical to the transport of this complex patient population.

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

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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.

Incidence of Heparin-Induced Thrombocytopenia in Patients With Newly Implanted Mechanical Circulatory Support Devices

BACKGROUND

Heparin exposure and device-related thrombocytopenia complicate the diagnosis of heparin-induced thrombocytopenia (HIT) in patients receiving mechanical circulatory support (MCS). To improve anticoagulation management for patients with newly implanted MCS devices, incidence of confirmed HIT needs to be further characterized.

OBJECTIVES

The purpose of this study is to describe the incidence of HIT and clinical utility of the 4Ts score in patients with newly implanted MCS devices.

METHODS

This is a retrospective analysis of MCS patients receiving unfractionated heparin from 2014 to 2017. The primary end point was incidence of laboratory-confirmed HIT. Strong positive, likely positive, low probability, and negative HIT categories were established based on heparin-induced platelet antibody (HIPA) and serotonin release assay (SRA). Secondary end points include characterization of platelet trends, argatroban use, incidence of HIT among each of the MCS devices, and utility of 4Ts score.

RESULTS

A total of 342 patient encounters met inclusion criteria, of which 68 HIPA tests and 25 SRAs were ordered. The incidence of HIT was 0.88% (3/342) and 4.4% (3/68) in patients with suspected HIT. Of the 68 HIPA tests, 3 (4.4%) were considered strong positive and 3 of the 25 SRAs were positive. Median 4Ts score was 4 [2.5-4] and optical density 0.19 [0.11-0.54]. The positive predictive value for the 4Ts score was 0.15 (CI = 0.03-0.46) and negative predictive value, 0.93 (CI = 0.82-0.98).

CONCLUSION AND RELEVANCE

HIT occurs infrequently with newly implanted MCS devices. The 4Ts score appears to have a high negative predictive value for ruling out HIT.

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.

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 Acute Heart Failure Complicated by Cardiogenic Shock

Acute heart failure is a potentially life-threatening condition that can lead to cardiogenic shock, which is associated with hypotension and organ failure. Although there have been many studies on the treatment for cardiogenic shock, early mortality remains high at 40–50%. No new medicines for cardiogenic shock have been developed. Recently, there has been a gradual decline in the use of the intra-aortic balloon pump mainly due to a lack of adequate hemodynamic support. Extracorporeal membrane oxygenation and the percutaneous ventricular assist device have become more widely used in recent years. A thorough understanding of the mechanisms of such mechanical support devices and their hemodynamic effects, components of the devices, implantation technique, management, criteria for indications or contraindications of use, and clinical outcomes as well as multidisciplinary decision making may improve the outcomes in patients experiencing cardiogenic shock.

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.

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.

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.

Standardization of Impella®-assisted patient management

The presence of high-risk features on candidates to percutaneous revascularization is increasingly leading to Impella®-assisted procedures (IAPs). While IAPs are safe and effective procedures, they still require managing a degree of complexity. Clinicians often rely on their ability to recall every step of operative procedures. However, during stressful situations, levels of cognitive function are compromised leading to planning and execution failures and decreased safety. Many high-risk activities such as aviation, aerospace industry, and nuclear plants have been using protocols, standardized procedures and checklists for many years. The purpose of the present article is to make a proposal for the standardization of ordinary medical activities required outside the Cath Lab for the management of patients before and after IAPs.