Heparin-Free Purge Solutions May Keep Impella Pumps Running During ECMO Support

When a patient’s heart fails so severely that neither drugs nor a single mechanical device can keep blood moving, intensive care teams sometimes reach for a combination known as ECPELLA: extracorporeal membrane oxygenation, or ECMO, running in parallel with the Impella percutaneous ventricular assist device. The pairing is one of the most aggressive forms of temporary mechanical circulatory support in modern critical care, and it comes with an unavoidable engineering problem. Both devices place large foreign surfaces into continuous contact with flowing blood, so the patient must remain systemically anticoagulated for as long as the circuits are in place. Yet each device also brings its own anticoagulation considerations, and one of the least settled questions is remarkably simple to state: what fluid should be used to keep the Impella motor housing free of clot? A new brief communication from Mayo Clinic investigators, published in the Journal of Artificial Organs, adds a carefully caveated data point to that debate.

The Impella family of devices works by drawing blood from the left ventricle through an inlet area near the pump’s tip and expelling it into the ascending aorta, providing up to several liters per minute of forward flow while simultaneously unloading the failing ventricle. The pump motor and bearing assembly sit within the blood stream, and heat and mechanical stress make that region a nidus for thrombus formation. To prevent clot from accumulating around the motor, the device continuously flushes a sterile purge solution through the narrow clearance space between the rotor and the housing; the solution then exits into the circulation. Because this purge fluid is delivered directly into the patient’s blood, whatever is dissolved in it becomes part of the patient’s systemic drug exposure. Historically, the manufacturer’s instructions have called for heparin to be added to the purge solution, so the purge line acts as a continuous low-dose heparin infusion on top of whatever systemic anticoagulation the patient is already receiving.

That arrangement is straightforward when Impella is used alone, but it becomes genuinely complicated when ECMO is added. Patients on ECPELLA support are typically managed with systemic anticoagulation to protect the oxygenator and tubing of the extracorporeal circuit, guided by protocols such as those issued by the Extracorporeal Life Support Organization, whose 2021 adult and pediatric anticoagulation guidelines consolidated contemporary practice. Layering a heparin-containing purge on top of systemic heparin, or on top of an alternative agent such as bivalirudin, creates a second, parallel route of anticoagulant delivery whose contribution to the total dose is not independently measured by standard monitoring. Clinicians therefore face a balancing act: enough anticoagulation to protect two devices and a circuit, but not so much that bleeding, the most common complication of mechanical circulatory support, becomes life-threatening. Some centers have responded by removing heparin from the purge bag entirely, running the purge with anticoagulant-free solutions such as 5% dextrose in water or sodium bicarbonate, and relying on systemic anticoagulation to protect the pump.

The question is whether an anticoagulant-free purge actually protects the device. The purge flow rate is titrated to maintain a specified pressure gradient across the purge circuit, which serves as a proxy for patency of the tiny channels that bathe the motor; if those channels clot, purge pressure rises, the purge rate climbs to compensate, and in the worst case the pump malfunctions. Prior single-center experiences, including analyses of heparin 25 units per milliliter purge solutions and separate evaluations of bicarbonate-based purge solutions in patients with cardiogenic shock supported by Impella, have suggested that non-standard purge strategies can be workable, but the data remain limited and the patients most likely to receive ECPELLA, those in profound cardiogenic shock, have been underrepresented. The new study by Nathaniel J. Martin, Christoph G. S. Nabzdyk, Scott D. Nei, Andrew N. Rosenbaum, Troy G. Seelhammer, and Patrick M. Wieruszewski was designed to examine exactly this gap: Impella device function in patients receiving combined ECMO and Impella support, stratified by whether their purge solution contained heparin or not.

The design was observational and modest in scale, and the authors are explicit about its limits. The team identified 25 patients supported with ECPELLA at their institution. Fourteen of these patients received an anticoagulant-free purge solution, either 5% dextrose or sodium bicarbonate, while the remaining 11 received a heparin-containing purge solution. The median duration of ECPELLA support was five days, a duration long enough for purge-related thrombosis to become clinically apparent if it were going to occur. The primary observation of interest was Impella device malfunction attributable to purge failure, the outcome that would most directly signal that an anticoagulant-free purge was inadequate to keep the motor housing clear. Ethical approval for the study came from the Mayo Clinic Institutional Review Board, with a waiver of informed consent, consistent with the retrospective review of clinical care.

The headline finding is stark in its simplicity. Across the entire cohort, the only episode of Impella device malfunction occurred in a patient in the heparin-containing group. No patient in the anticoagulant-free group experienced a purge-related device failure during their course of support, and device longevity appeared acceptable in both groups. Read at face value, the result suggests that dextrose- or bicarbonate-based purge solutions, paired with systemic anticoagulation, did not compromise the mechanical integrity of the Impella during a median of five days of combined support. In an environment where every additional unit of heparin delivered through the purge line potentially shifts a critically ill patient’s hemostatic balance, a strategy that removes that infusion without evident device harm is clinically meaningful, even if the evidence behind it is still thin.

The authors themselves are careful not to overstate the case, and their caution is warranted for reasons that go to the heart of how small clinical studies work. With only 25 patients and a low overall event rate, the study cannot exclude a modest increase in device malfunction risk associated with anticoagulant-free purge solutions; the single malfunction in the heparin group, far from indicting heparin, illustrates precisely how noisy such comparisons are at this scale. Bleeding outcomes, thromboembolic events, and hemolysis, all of which matter enormously in this population, are not the focus of the abstract-level reporting, and confounding by indication is a live concern: the choice of purge solution likely reflected evolving institutional practice and individual patient characteristics rather than random assignment. The conclusion the authors draw is correspondingly measured. Given the low event rate and the apparent maintenance of acceptable device longevity, they write, use of anticoagulant-free purge solutions alongside systemic anticoagulation in ECPELLA patients may be reasonable, but the strategy requires validation in an appropriately powered study.

Even so, the study contributes to a broader and increasingly visible conversation about how anticoagulation should be managed across the growing arsenal of temporary circulatory support devices. Pharmacotherapy reviews have called for optimization of anticoagulation in Impella-supported patients, noting the tension between manufacturer recommendations, center-specific protocols, and the absence of definitive trial evidence. Comparisons of bivalirudin versus heparin for systemic anticoagulation during ECMO, published in Critical Care Medicine by members of the same Mayo group, reflect the same underlying effort to rationalize hemostatic management in extracorporeal support. The purge solution sits at an unusual intersection within this landscape: it is simultaneously a device-maintenance fluid and a systemic drug delivery route, and it is frequently overlooked in discussions that focus on the more visible systemic anticoagulants. Recognizing the purge line as a pharmacologic exposure, and studying it as one, is a conceptual step forward for the field.

For the bedside intensivist, pharmacist, and perfusionist managing an ECPELLA patient tonight, the practical takeaway is not a new protocol but a new data point in an evolving conversation. Anticoagulant-free purge solutions, whether 5% dextrose or sodium bicarbonate, have now been used in a consecutive series of ECPELLA patients at a high-volume center without evident compromise of device function over a median of five days of support. That observation will not end the debate, and no one should abandon heparinized purge on the strength of 25 patients, but it legitimizes the strategy as a subject for the large, prospectively designed comparative study it deserves. Until such a study exists, the choice of purge solution will remain a matter of institutional protocol and clinical judgment, exercised within the same delicate balance that defines all of extracorporeal support: keeping the blood fluid enough to survive the machine, and the patient solid enough to survive the bleeding. This small study suggests the balance can be struck without heparin in the purge bag, and that alone makes it worth the field’s attention.

Subject of Research: Impella purge solution strategy and device function in patients receiving combined ECMO and Impella (ECPELLA) support

Article Title: Impella purge solutions in patients receiving extracorporeal membrane oxygenation

Article References: Martin, N. J., Nabzdyk, C. G. S., Nei, S. D., Rosenbaum, A. N., Seelhammer, T. G., & Wieruszewski, P. M. (2026). Impella purge solutions in patients receiving extracorporeal membrane oxygenation. Journal of Artificial Organs, 29(4), Article 64. https://doi.org/10.1007/s10047-026-01595-2

Image Credits: AI Generated

DOI: 10.1007/s10047-026-01595-2

Keywords: Impella, ECMO, ECPELLA, purge solution, anticoagulation, heparin, mechanical circulatory support, cardiogenic shock, left ventricular unloading, device malfunction, critical care, ventricular assist device