Development of a hemodynamically optimized outflow cannula for cardiopulmonary bypass

Area of Science:

• Biomedical Engineering
• Cardiovascular Surgery
• Fluid Dynamics

Background:

• The outflow cannula jet during cardiopulmonary bypass (CPB) poses risks, including cerebral hypoxia and stroke, due to high velocities and potential plaque mobilization.
• Existing CPB cannulas can lead to altered flow dynamics and adverse neurological outcomes.
• A validated computational fluid dynamics (CFD) model was previously developed to analyze CPB flow conditions.

Purpose of the Study:

• To develop and evaluate a novel CPB outflow cannula designed to mitigate the risks associated with the cannula jet.
• To reduce jet velocities and improve cerebral blood flow during CPB procedures.
• To enhance patient safety and neurological outcomes in patients undergoing CPB.

Main Methods:

• Application of a validated CFD model to iteratively design and analyze a new CPB outflow cannula, termed the Multi-Module Cannula (MMC).
• The MMC design incorporates an inner wall for smooth blood guidance and an elliptical outlet diffuser.
• Comparative analysis of hemodynamic parameters (pressure drop, velocities) between the MMC and a standard cannula under standard CPB conditions (5 L/min).

Main Results:

• The MMC demonstrated a lower pressure drop (61 mm Hg) compared to a standard cannula (68 mm Hg).
• Maximum velocities were reduced from 3.7 m/s to 3.3 m/s with the MMC.
• Velocities within the cannula jet were significantly decreased to 1.6 m/s, and cerebral blood flow increased to near-physiological levels (715 mL/min).

Conclusions:

• The novel Multi-Module Cannula (MMC) effectively reduces high-velocity jets and improves cerebral blood flow during cardiopulmonary bypass.
• The MMC shows superior performance compared to standard CPB cannulas, potentially reducing the incidence of stroke and cerebral hypoxia.
• Further design refinements and optimized insertion techniques are being explored to maximize the benefits of the MMC.