Endovascular Engineering, the Menlo Park device maker known as E2, said 12 October 2026 that FDA cleared Hēlo Return, a system it calls the first blood-return accessory cleared for use with continuous vacuum aspiration thrombectomy. Paired with the company's existing Hēlo Thrombectomy System, cleared in December 2025, the combination is meant to remove blood clots from the pulmonary arteries without the significant blood loss that aspiration thrombectomy typically causes.
Hēlo's clearance, in four figures
Figures from E2's own announcements and SCAI/VIVA conference presentations of the ENGULF study.
A category two acquisitions just revalued
E2 clears this milestone into a field reshaped by consolidation. Stryker completed its roughly $4.9 billion acquisition of Inari Medical, maker of the FlowTriever and ClotTriever systems, in February 2025. Boston Scientific has agreed to acquire Penumbra, maker of the Indigo aspiration system, for roughly $14.5 billion, a deal expected to close in 2026. Both incumbents' thrombectomy lines now sit inside much larger medtech balance sheets — leaving E2 and privately held Imperative Care, whose Symphony Thrombectomy System won its own PE clearance in September 2025, as the venture-backed challengers still racing on clearances and clinical data rather than acquisition scale.
The category Hēlo Return just entered
$2.43B → $5.37B
Global thrombectomy devices market, 2026 to 2036, as forecast by Meticulous Research.
Sources: Meticulous Research, Thrombectomy Devices Market report · Meticulous Research, Venous Thromboembolism Treatment Market report (divergent scope)
Regulatory News outlook
We expect blood-return accessories to become a standard feature of large-bore aspiration thrombectomy rather than a standalone product category, so Hēlo Return's near-term value is better read as protecting E2's share of the thrombectomy-devices market Meticulous Research tracks than as opening a distinct new one.
How we got here: No new figure is computed; this reads E2's accessory as competing within Meticulous Research's existing $2.43 billion (2026) to $5.37 billion (2036) thrombectomy-devices forecast rather than adding to it, since blood return is a feature of the procedure, not a separately billed device category today.
Hēlo against pulmonary embolism's largest players
| Product | Mechanism | Ownership | US status |
|---|---|---|---|
| Hēlo Platform (E2) | Continuous vacuum aspiration with integrated blood return | Private, venture-backed | FDA cleared, Dec 2025 & Oct 2026 |
| FlowTriever / ClotTriever (Inari Medical) | Mechanical aspiration and clot capture | Stryker subsidiary since Feb 2025 | FDA cleared (established devices) |
| Indigo System (Penumbra) | Computer-assisted vacuum thrombectomy | Penumbra, pending Boston Scientific deal | FDA cleared (established devices) |
| Symphony Thrombectomy System (Imperative Care) | Large-bore continuous vacuum aspiration | Private | FDA cleared, Sep 2025 (PE indication) |
From each company's own disclosures, FDA clearance announcements and public acquisition filings; not a clinical comparison.
Suction that gives blood back
Continuous vacuum aspiration draws a steady, pump-driven negative pressure through a catheter to pull a clot out of a blood vessel, instead of the stop-start suction of a manual syringe. The trade-off is that the aspirated fluid is largely the patient's own blood, not just clot material — enough, over a long procedure, to force a physician to stop early or risk symptomatic blood loss. Hēlo Return is built to filter and reinfuse that blood back into the patient during the same procedure, without an external transfusion, while the thrombectomy continues.
Three things the blood-loss data shows and doesn't
A 97% reduction, as reported
In a 130-patient comparative analysis presented at SCAI 2026, median blood loss was 10cc with Hēlo's blood-return system in use versus 340cc without it, with no significant difference reported in blood-quality markers such as hemolysis or platelet activation.
Not a randomized trial
The comparison split 40 patients who received the blood-return system against 90 who did not, in a non-randomized, unequal-size analysis — a real result, but one that has not yet been tested in a controlled design.
A contested "first"
E2 calls Hēlo Return the first blood-return system cleared for continuous vacuum aspiration; competitor Imperative Care made a similarly framed "first" claim for its own large-bore continuous-vacuum system when it won FDA clearance in September 2025 — a reminder that marketing "firsts" in this category are competing claims, not adjudicated facts.
What the ENGULF data showed before this clearance
Hēlo Return's clearance builds on the ENGULF pivotal study, a single-arm investigational trial of the underlying thrombectomy system in 105 patients with acute intermediate-risk pulmonary embolism across 19 U.S. hospitals. Investigators reported a 48-hour major adverse event rate of 0.95% and a mean 25.1% reduction in right-ventricle-to-left-ventricle size ratio, a standard measure of PE severity, with 30-day all-cause mortality of 2.85% and symptomatic PE recurrence of 3.80%. Dr. Andrew Klein presented the late-breaking data at VIVA 2025 in November 2025, ahead of the original Hēlo Thrombectomy System's own FDA clearance the following month.
“With dual FDA clearances in hand, we are accelerating our plans to deliver this complete solution to a broad range of physicians and patients.” Dan Rose, Chief Executive Officer, Endovascular Engineering — 12 October 2026 announcement
From a funnel patent to a second clearance
Hēlo's path from founding to a paired clearance
- 2019
E2 founded
Luis Savastano and Mike Rosenthal found Endovascular Engineering in Menlo Park, California.
- 2023
$42M Series B
415 Capital and S3 Ventures co-lead a Series B round backing the ENGULF pivotal study.
- November 2025
ENGULF pivotal data presented
Dr. Andrew Klein presents late-breaking ENGULF results at VIVA 2025, reporting the trial's safety and efficacy endpoints met.
- 18 December 2025
Hēlo Thrombectomy System cleared
FDA grants 510(k) clearance under K252956 for peripheral mechanical thrombectomy with aspiration.
- August 2024
Dan Rose named CEO
Rose, previously CEO of LimFlow through its acquisition by Inari Medical, joins as E2's chief executive; co-founder Mike Rosenthal moves to chief operating officer.
- April 2026
$80M Series C
Gilde Healthcare and Norwest co-lead a Series C round to fund commercialization, bringing disclosed venture funding to more than $137 million.
- April 2026
Blood-loss data presented
E2 presents its 130-patient blood-return comparative analysis at SCAI 2026 in Montreal.
- 12 October 2026
Hēlo Return cleared
FDA clears the integrated blood-return system, which E2 pairs with the existing thrombectomy clearance as the Hēlo Platform.
- Ahead
A peer-reviewed publication still pending
E2's pivotal and blood-loss data have been presented at conferences but, as of this clearance, not yet published in a peer-reviewed journal.
What this clearance leaves open: Hēlo Return's own 510(k) number is not yet listed in FDA's public database, so this article cites E2's own announcement and independent trade coverage rather than a regulator record it could open directly. The ENGULF pivotal cohort's full results and the blood-loss comparative analysis have both been presented at medical conferences but not yet published in a peer-reviewed journal, and the blood-loss figures themselves come from a non-randomized, unequal-size comparison rather than a controlled trial.
- Clearance: FDA 510(k) for Hēlo Return, 12 October 2026, paired with the Hēlo Thrombectomy System (K252956, cleared 18 December 2025).
- Clinical basis: ENGULF pivotal study (105 patients, 19 US sites) plus a 130-patient blood-loss comparative analysis presented at SCAI 2026.
- Funding: at least $137 million disclosed across a 2023 Series B and an April 2026 Series C.
- Not yet public: Hēlo Return's own 510(k) number, and peer-reviewed publication of either the ENGULF pivotal results or the blood-loss analysis.
Sources & further reading
- BioSpace (press release), "E2 Secures Dual FDA Clearances for the Hēlo Platform, Introducing a PE Thrombectomy System with Integrated Blood Return," 12 October 2026. biospace.com
- EVToday, "FDA Clears E2 Hēlo Thrombectomy System and Integrated Blood Return System." evtoday.com
- DI Cardiology, "Thrombectomy System, Blood Return System Get FDA Approval," 13 October 2026. dicardiology.com
- FDA 510(k) Premarket Notification database, K252956 (Hēlo Thrombectomy System). accessdata.fda.gov
- TCTMD, "ENGULF: Novel PE Thrombectomy Device Minimizes Blood Loss." tctmd.com
- FierceBiotech, "E2 lands $80M Series C for next-gen thrombectomy treatment." fiercebiotech.com
- BusinessWire, "Imperative Care Announces FDA Clearance of Symphony Thrombectomy System, the First Large-Bore, Continuous Vacuum System for Treatment of Pulmonary Embolism," 2 September 2025. businesswire.com
Regulatory News reports on public regulatory documents. It is not legal advice, and the primary sources above govern. If we have made an error, we will say so in public: see corrections.
Frequently asked questions
What exactly did FDA clear?
A 510(k) clearance, announced 12 October 2026, for Hēlo Return, E2's blood-return system for use during continuous vacuum aspiration thrombectomy. The company pairs it with its Hēlo Thrombectomy System, cleared separately under K252956 on 18 December 2025, to form what E2 calls the Hēlo Platform. Hēlo Return's own 510(k) number was not listed in FDA's public database as of publication; this article will update it once indexed.
What problem does a blood-return system solve?
Aspiration thrombectomy removes a clot by suctioning it out along with a volume of the patient's own blood. In a 130-patient comparative analysis E2 presented at SCAI 2026, median blood loss was 10cc with Hēlo's blood-return system versus 340cc without it — a reduction the company reports as statistically significant, though the two groups were not randomized and were unequal in size (40 versus 90 patients).
Is this E2's first FDA clearance?
No. The underlying Hēlo Thrombectomy System first cleared FDA review under K252956 on 18 December 2025. The 12 October 2026 news adds the integrated blood-return accessory, which E2 says is the first such system cleared for continuous vacuum aspiration specifically — a claim that overlaps with a similar "first" claim made by competitor Imperative Care for its own system in 2025.
Who else makes thrombectomy devices for pulmonary embolism?
Inari Medical's FlowTriever, now part of Stryker following a roughly $4.9 billion acquisition completed in February 2025, and Penumbra's Indigo system, with Penumbra itself under a pending roughly $14.5 billion acquisition by Boston Scientific, are the category's largest incumbents. Imperative Care's Symphony Thrombectomy System won FDA clearance for a PE indication in September 2025.
