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Published on: February 16, 2016
Hyperemia-free delineation of epicardial and microvascular impairments using a basal index
Kranthi K Kolli1, M A Effat, Srikara V Peelukhana
1Department of Mechanical and Materials Engineering, University of Cincinnati, 598 Rhodes Hall, PO Box 210072, Cincinnati, OH, 45221-0072, USA.
Insights
A new hyperemia-free index, basal pressure drop coefficient (bCDP), accurately assesses coronary artery disease severity and microvascular function. This index shows promise for detecting coronary artery disease without needing maximal hyperemia.
Area of Science:
- Cardiovascular Physiology
- Medical Diagnostics
Background:
- Assessing coronary lesion severity traditionally relies on hyperemia-inducing agents.
- Current methods like fractional flow reserve (FFR) and coronary flow reserve (CFR) require maximal hyperemia, limiting their clinical application.
- A hyperemia-free index could simplify and improve the assessment of coronary artery disease.
Purpose of the Study:
- To evaluate a novel hyperemia-free index, the basal pressure drop coefficient (bCDP), for assessing epicardial and microvascular coronary circulations.
- To determine if bCDP can differentiate between varying degrees of coronary stenosis and microvascular impairment without hyperemia.
Main Methods:
- The study involved 23 pigs with induced epicardial lesions and varied microcirculation states.
- Simultaneous measurements of distal coronary pressure and flow were recorded using a dual-sensor guidewire under baseline conditions.
- The basal pressure drop coefficient (bCDP) was calculated using fluid dynamics principles: transtenotic pressure drop divided by distal dynamic pressure.
Main Results:
- bCDP values significantly differed between normal (84 ± 18) and abnormal (124.5 ± 15.6) microcirculation.
- bCDP effectively distinguished between area stenosis (AS) < 50% (72.5 ± 16.1) and AS > 50% (136 ± 17.2).
- bCDP showed significant correlations with established hyperemic parameters: FFR (r = 0.42) and CDP (r = 0.50).
Conclusions:
- The basal pressure drop coefficient (bCDP) is a promising index for simultaneously assessing epicardial stenosis and microvascular function.
- bCDP offers a hyperemia-free approach, potentially simplifying the diagnosis of coronary artery disease.
- Clinical validation of bCDP is warranted for its application in detecting coronary artery disease.
Abstract:
The assessment of functional coronary lesion severity using intracoronary hemodynamic parameters like the pressure-derived fractional flow reserve and the flow-derived coronary flow reserve are known to rely critically on the establishment of maximal hyperemia. We evaluated a hyperemia-free index, basal pressure drop coefficient (bCDP), that combines pressure and velocity for simultaneous assessment of the status of both epicardial and microvascular circulations. In 23 pigs, simultaneous measurements of distal coronary arterial pressure and flow were performed using a dual-sensor tipped guidewire in the settings of both normal and abnormal microcirculation with the presence of epicardial lesions of area stenosis (AS) < 50% and AS > 50%. The bCDP, a parameter based on fundamental fluid dynamics principles, was calculated as the transtenotic pressure-drop divided by the dynamic pressure in the distal vessel, measured under baseline (without hyperemia) conditions. The group mean values of bCDP for normal (84 ± 18) and abnormal (124.5 ± 15.6) microcirculation were significantly different. Similarly, the mean values of bCDP from AS < 50% (72.5 ± 16.1) and AS > 50% (136 ± 17.2) were also significantly different (p < 0.05). The bCDP could significantly distinguish between lesions of AS < 50% to AS > 50% under normal microcirculation (52.1 vs. 85.8; p < 0.05) and abnormal microcirculation (84.9 vs. 172; p < 0.05). Further, the bCDP correlated linearly and significantly with the hyperemic parameters FFR (r = 0.42, p < 0.05) and CDP (r = 0.50, p < 0.05). The bCDP is a promising clinical diagnostic parameter that can independently assess the severity of epicardial stenosis and microvascular impairment. We believe that it has an immediate appeal for detection of coronary artery disease if validated clinically.
