Blood return system dramatically reduces blood loss during pulmonary thrombectomy

The first comparative analysis from the ENGULF (A Safety and Feasibility Single-Arm Study of a Novel Catheter Thrombectomy Device For the Treatment of Pulmonary Embolism) trial shows that using blood return during continuous aspiration thrombectomy dramatically reduces blood loss by 97%, while maintaining hemodynamic efficacy and improving procedural efficiency. Researchers presented the late-breaking data today at the Society for Cardiovascular Angiography & Interventions (SCAI) 2026 Scientific Sessions & Canadian Association of Interventional Cardiology/Association Canadienne de cardiologie d'intervention (CAIC-ACCI) Summit in Montreal. 

Mechanical thrombectomy is a minimally invasive procedure in which physicians remove blood clots from the lungs in patients with pulmonary embolism (PE). However, the procedure can cause significant blood loss, often forcing physicians to choose between stopping early and leaving blood clots behind or risking serious bleeding. 

The ENGULF study was a prospective, investigational device exemption (IDE) study evaluating the treatment of patients with pulmonary embolism (PE) using the Hēlo® Thrombectomy System. It is the first prospective IDE study to assess mechanical thrombectomy in PE patients with and without blood return, including evaluation of blood quality. In this comparative analysis, researchers studied 130 patients, comparing outcomes for those treated with Hēlo® Blood Return System (BRS) versus standard continuous aspiration without blood return. The first-of-its-kind BRS allows a patient to receive their own blood after it's filtered and returned, while removing the clot by simultaneously combining the power of aspiration with advanced mechanical clot disruption. Researchers treated 40 of the 130 patients with BRS during the procedure and 90 with continuous aspiration without blood return. 

Using BRS reduced median blood loss by 97% (10cc vs. 340cc, p<0.001). Physicians completed all BRS procedures without adjunctive therapy to manage blood loss, compared with five interventions in the non-BRS group. The BRS group experienced no major adverse events, and 88% of BRS procedures were completed with a single pass through the heart. The primary endpoint of effective blood flow was higher in the BRS group with a hemodynamic efficacy (RV/LV reduction) of 28%, compared to 25% in the non-BRS group (p=0.05).

This first-of-its-kind BRS permits operators to remove more thrombus without having to be concerned about blood loss. The BRS system provides confidence to operators in knowing they are returning high-quality blood back to the patient in a safer, more timely, and effective manner. This, in turn, allows operators to be more aggressive about clot removal, which should make patients feel better faster."

Andrew Klein, MD, FSCAI, interventional cardiologist at Piedmont Heart Institute, Atlanta