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Hemodynamic diagnostics of epicardial coronary stenoses: in-vitro experimental and computational study
Rupak K Banerjee1, Koustubh D Ashtekar, Tarek A Helmy
1Department of Mechanical, Industrial and Nuclear Engineering, 601B Rhodes Hall, University of Cincinnati, Clifton Avenue, Cincinnati, OH, USA. rupak.banerjee@uc.edu
Insights
The pressure drop coefficient (CDPe) effectively assesses coronary stenosis severity, even with guidewire interference. This fluid dynamics parameter offers a reliable method for unmasking true stenosis severity in clinical practice.
Area of Science:
- Cardiovascular Research
- Biomedical Engineering
- Fluid Dynamics
Background:
- Invasive assessment of epicardial coronary stenosis using pressure/flow guidewires can overestimate pressure drop and underestimate flow, potentially masking true severity.
- Fundamental fluid dynamics principles offer a diagnostic parameter to accurately evaluate stenosis severity.
- Understanding pressure recovery downstream of stenoses is crucial for accurate hemodynamic assessment.
Purpose of the Study:
- To characterize the pressure drop coefficient (CDPe) as a diagnostic parameter for epicardial coronary stenosis.
- To evaluate the impact of guidewire insertion on trans-stenotic pressure measurements.
- To assess pressure recovery downstream of coronary stenoses.
Main Methods:
- Developed and tested in-vitro models of moderate, intermediate, and severe coronary stenosis.
- Measured trans-stenotic pressure drop and flow non-invasively and invasively (with guidewire).
- Calculated the pressure drop coefficient (CDPe) and pressure recovery factor (eta) based on fluid dynamics principles.
Main Results:
- Guidewire insertion significantly impacts pressure drop and flow measurements, particularly for intermediate stenoses.
- The pressure drop coefficient (CDPe) showed a significant increase from moderate to severe stenosis (17 to 287).
- The pressure recovery factor (eta) significantly decreased from moderate to severe stenosis (0.54 to 0.37).
Conclusions:
- The pressure drop coefficient (CDPe) is a robust parameter for evaluating coronary stenosis severity, minimally affected by guidewire presence.
- CDPe demonstrates significant differences between moderate and severe stenoses, making it clinically valuable.
- This study validates CDPe as a reliable tool for unmasking the true hemodynamic severity of epicardial coronary stenosis.
Background:
The severity of epicardial coronary stenosis can be assessed by invasive measurements of trans-stenotic pressure drop and flow. A pressure or flow sensor-tipped guidewire inserted across the coronary stenosis causes an overestimation in true trans-stenotic pressure drop and reduction in coronary flow. This may mask the true severity of coronary stenosis. In order to unmask the true severity of epicardial stenosis, we evaluate a diagnostic parameter, which is obtained from fundamental fluid dynamics principles. This experimental and numerical study focuses on the characterization of the diagnostic parameter, pressure drop coefficient, and also evaluates the pressure recovery downstream of stenoses.
Methods:
Three models of coronary stenosis namely, moderate, intermediate and severe stenosis, were manufactured and tested in the in-vitro set-up simulating the epicardial coronary network. The trans-stenotic pressure drop and flow distal to stenosis models were measured by non-invasive method, using external pressure and flow sensors, and by invasive method, following guidewire insertion across the stenosis. The viscous and momentum-change components of the pressure drop for various flow rates were evaluated from quadratic relation between pressure drop and flow. Finally, the pressure drop coefficient (CDPe) was calculated as the ratio of pressure drop and distal dynamic pressure. The pressure recovery factor (eta) was calculated as the ratio of pressure recovery coefficient and the area blockage.
Results:
The mean pressure drop-flow characteristics before and during guidewire insertion indicated that increasing stenosis causes a shift in dominance from viscous pressure to momentum forces. However, for intermediate (approximately 80%) area stenosis, which is between moderate (approximately 65%) and severe (approximately 90%) area stenoses, both losses were similar in magnitude. Therefore, guidewire insertion plays a critical role in evaluating the hemodynamic severity of coronary stenosis. More importantly, mean CDPe increased (17 +/- 3.3 to 287 +/- 52, n = 3, p < 0.01) and mean eta decreased (0.54 +/- 0.04 to 0.37 +/- 0.05, p < 0.01) from moderate to severe stenosis during guidewire insertion.
Conclusion:
The wide range of CDPe is not affected that much by the presence of guidewire. CDPe can be used in clinical practice to evaluate the true severity of coronary stenosis due to its significant difference between values measured at moderate and severe stenoses.
