Impeller inner diameter in a miniaturized centrifugal blood pump

Area of Science:

• Biomedical Engineering
• Cardiovascular Devices
• Hemodynamics

Background:

• Miniaturized centrifugal blood pumps are crucial for mechanical circulatory support.
• Impeller internal diameter (ID) is a key design parameter influencing pump performance.
• Evaluating hemolysis and thrombogenicity is essential for blood pump safety and efficacy.

Purpose of the Study:

• To investigate the impact of impeller internal diameter (ID) on hydraulic performance, hemolysis, and thrombogenicity.
• To determine optimal combinations of impeller ID and housing inlet offset for improved blood compatibility.
• To assess the suitability of different impeller designs for long-term use in blood pumps.

Main Methods:

• Fabricated two 35 mm outer diameter impellers with 8 mm and 12 mm IDs.
• Combined impellers with housings featuring 3.8 mm and 4.5 mm eccentric inlet port offsets.
• Evaluated hydraulic performance and hemolysis in a mock circuit.
• Assessed thrombogenicity through 2-day ex vivo studies, with extended 14-day ex vivo and 10-day in vivo studies for select configurations.

Main Results:

• Hydraulic performance was largely unaffected by impeller ID.
• The 8 mm ID with 3.8 mm offset and 12 mm ID with 4.5 mm offset showed reduced hemolysis.
• The 12 mm ID with 4.5 mm offset demonstrated minimal thrombogenicity in longer-term studies, with no thrombus formation around the top bearing.

Conclusions:

• Impeller ID has a limited effect on the hydraulic performance of miniaturized centrifugal blood pumps.
• Optimizing the combination of impeller ID and inlet port offset is critical for minimizing hemolysis.
• Larger impeller IDs appear to reduce thrombogenicity, particularly around the top bearing, suggesting improved biocompatibility.