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Influence of coronary collateral flow on coronary diagnostic parameters: an in vitro study
Srikara Viswanath Peelukhana1, Lloyd H Back, Rupak K Banerjee
1Department of Mechanical Engineering, University of Cincinnati, Cincinnati, OH 45221, USA.
Insights
Downstream collaterals can alter coronary stenosis measurements, potentially misinterpreting severity. This study highlights how collateral flow affects diagnostic parameters, impacting intervention decisions.
Area of Science:
- Cardiovascular Physiology
- Medical Device Engineering
- Interventional Cardiology
Background:
- Functional severity of coronary stenosis is crucial for treatment decisions.
- Diagnostic parameters rely on pressure and flow measurements at the stenosis site.
- Downstream collaterals can alter these measurements, complicating assessment.
Purpose of the Study:
- To investigate the impact of downstream collaterals on coronary stenosis diagnostic parameters.
- To evaluate potential misinterpretations of stenosis severity due to collateral flow.
- To assess the influence of collaterals on Fractional Flow Reserve (FFR), Lesion Flow Coefficient (LFC), and Pressure Drop Coefficient (CDP).
Main Methods:
- Utilized a physiological representative in vitro coronary flow-loop.
- Measured pressure and flow with and without simulated downstream collaterals.
- Calculated FFR, LFC, and CDP for varying stenosis severities and collateral flows.
Main Results:
- For intermediate stenosis (80% area blockage), FFR increased from 0.74 to 0.77 with collaterals.
- LFC increased from 0.58 to 0.62, while CDP decreased from 47 to 42 with collaterals.
- These parameter shifts indicate potential underestimation or overestimation of stenosis severity.
Conclusions:
- Variability in diagnostic parameters due to collaterals can lead to misinterpretation of coronary stenosis severity.
- This misinterpretation may result in the erroneous postponement of necessary coronary interventions.
- Accurate assessment requires considering the influence of functional downstream collaterals.
Abstract:
Functional severity of coronary stenosis is often assessed using diagnostic parameters. These parameters are evaluated from the combined pressure and/or flow measurements taken at the site of the stenosis. However, when there are functional collaterals operating downstream to the stenosis, the coronary flow-rate increases, and the pressure in the stenosed artery is altered. This effect of downstream collaterals on different diagnostic parameters is studied using a physiological representative in vitro coronary flow-loop. The three diagnostic parameters tested are fractional flow reserve (FFR), lesion flow coefficient (LFC), and pressure drop coefficient (CDP). The latter two were discussed in recent publications by our group (Banerjee et al., 2007, 2008, 2009). They are evaluated for three different severities of stenosis and tested for possible misinterpretation in the presence of variable collateral flows. Pressure and flow are measured with and without downstream collaterals. The diagnostic parameters are then calculated from these readings. In the case of intermediate stenosis (80% area blockage), FFR and LFC increased from 0.74 to 0.77 and 0.58 to 0.62, respectively, for no collateral to fully developed collateral flow. Also, CDP decreased from 47 to 42 for no collateral to fully developed collateral flow. These changes in diagnostic parameters might lead to erroneous postponement of coronary intervention. Thus, variability in diagnostic parameters for the same stenosis might lead to misinterpretation of stenosis severity in the presence of operating downstream collaterals.
