Ultrasonic evaluation of erythrocyte aggregation dynamics

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Hematology

Background:

• Blood rheology is crucial for understanding physiological and pathological conditions.
• Hematocrit significantly influences blood flow properties, including aggregation dynamics.
• Oscillatory flow conditions are relevant to various vascular environments.

Purpose of the Study:

• To investigate the aggregation and disaggregation kinetics of blood with varying hematocrit levels.
• To analyze blood behavior under oscillatory flow within a distensible horizontal tube.
• To quantify the impact of hematocrit and shear stress on blood aggregation dynamics.

Main Methods:

• Utilized a 10 MHz B-mode ultrasonic scanner to measure developing echo intensity of blood samples.
• Simulated oscillatory flow in a distensible horizontal tube with blood of different hematocrit values.
• Monitored echo intensity changes to assess aggregation and disaggregation rates upon flow stoppage and resumption.

Main Results:

• Early blood aggregation was detectable within 10 seconds of flow cessation.
• The rate of aggregation (echo intensity buildup) and disaggregation (echo intensity reduction) was inversely related to hematocrit.
• Blood with 60% hematocrit exhibited no significant aggregation over 5 minutes.
• Increased shear stress upon flow resumption led to rapid decreases in aggregation.

Conclusions:

• Hematocrit is a critical determinant of blood aggregation and disaggregation rates in oscillatory flow.
• Disaggregation of blood under flow resumption was consistently faster than aggregation following flow stoppage.
• Ultrasonic echo intensity measurement provides a sensitive method for evaluating blood aggregation dynamics.