Simulation of coronary artery revascularization.

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cardiovascular Surgery

Background:

• Aorto-coronary bypass anastomoses are critical in treating coronary artery disease.
• Understanding blood flow dynamics at the anastomosis is essential for graft patency and patient outcomes.
• Previous simulations often used rigid tubing, not fully replicating physiological conditions.

Purpose of the Study:

• To simulate and visualize blood flow through various aorto-coronary bypass anastomosis geometries.
• To investigate the impact of pulsatile flow and stenoses on flow patterns in distensible versus rigid tubing.
• To compare different anastomotic angles (0, 45, 90 degrees) and their effects on flow characteristics.

Main Methods:

• Fabrication of distensible tubes mimicking vascular compliance.
• Utilized a pulsatile pump system with a blood-mimicking fluid (water-glycerine mixture).
• Employed dye injection and film recording for flow visualization in various anastomosis configurations and simulated stenoses (80-85% area reduction).

Main Results:

• Distensible tubes produced more realistic flow patterns than rigid tubes, particularly with stenoses.
• Pulsatile flow significantly enhanced fluid mixing compared to steady flow.
• Pulsatile flow in distensible, stenosed tubes showed retrograde flow, absent in steady flow or rigid tubes.
• A 0-degree anastomosis angle resulted in jetting and recirculation, while a 90-degree angle created helical flow distal to the anastomosis.

Conclusions:

• Distensible tubing and pulsatile flow are crucial for accurate simulation of aorto-coronary bypass hemodynamics.
• Stenoses and specific anastomotic angles significantly alter flow patterns, potentially impacting graft function.
• The observed retrograde flow in realistic simulations highlights a potential mechanism for graft complications.