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Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model
S V Peelukhana1, R K Banerjee, K K Kolli
1School of Dynamic Systems, Department of Mechanical Engineering, University of Cincinnati, Cincinnati, Ohio 45220, USA.
Insights
Heart rate does not impact measurements of coronary stenosis severity in patients with microvascular disease. Fractional flow reserve (FFR), pressure drop coefficient (CDP), and lesion flow coefficient (LFC) remain consistent across varying heart rates (HR).
Area of Science:
- Cardiovascular Physiology
- Interventional Cardiology
- Biomedical Engineering
Background:
- Assessing epicardial stenosis with microvascular disease (MVD) during interventions is complex due to hemodynamic variability.
- Heart rate (HR) is a key hemodynamic factor influencing the diagnosis of ischemic power.
- Existing methods may not accurately reflect stenosis severity under dynamic HR conditions.
Purpose of the Study:
- To evaluate the impact of variable HR and percent area stenosis (%AS) on pressure drop coefficient (CDP) and lesion flow coefficient (LFC) in the presence of MVD.
- To determine if CDP and LFC are independent of HR.
- To assess the diagnostic utility of CDP and LFC in differentiating stenosis severity under MVD conditions.
Main Methods:
- Created %AS and MVD in Yorkshire pigs using angioplasty balloons and microspheres.
- Measured simultaneous pressure drop (DP) and velocity.
- Calculated fractional flow reserve (FFR), CDP, and LFC, analyzing data by HR (<120 vs >120 bpm), %AS (<50 vs >50), and DP (<14 vs >14 mmHg) groups using regression and ANOVA.
Main Results:
- Regression analysis indicated HR independence from FFR, CDP, and LFC, but %AS dependence.
- ANOVA showed no significant differences in FFR, CDP, or LFC between HR groups (P > 0.05).
- Significant differences in FFR, CDP, and LFC were observed between %AS groups (P < 0.05), with a similar trend for DP groups.
Conclusions:
- In the presence of MVD, FFR, CDP, and LFC are not significantly affected by changes in HR.
- %AS and DP significantly influence FFR, CDP, and LFC.
- CDP and LFC show potential as reliable indicators of stenosis severity, independent of HR variations in MVD patients.
Abstract:
Diagnosis of the ischemic power of epicardial stenosis with concomitant microvascular disease (MVD) is challenging during coronary interventions, especially under variable hemodynamic factors like heart rate (HR). The goal of this study is to assess the influence of variable HR and percent area stenosis (%AS) in the presence of MVD on pressure drop coefficient (CDP; ratio of transstenotic pressure drop to the distal dynamic pressure) and lesion flow coefficient (LFC; ratio of %AS to the CDP at the throat region). We hypothesize that CDP and LFC are independent of HR. %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop (DP) and velocity were done in 11 Yorkshire pigs. Fractional flow reserve (FFR), CDP, and LFC were calculated for the groups HR < 120 and HR > 120 beats/min, %AS < 50 and %AS > 50, and additionally for DP < 14 and DP > 14 mmHg, and analyzed using regression and ANOVA analysis. Regression analysis showed independence between HR and the FFR, CDP, and LFC while it showed dependence between %AS and the FFR, CDP, and LFC. In the ANOVA analysis, for the HR < 120 beats/min and HR > 120 beats/min groups, the values of FFR (0.82 ± 0.02 and 0.82 ± 0.02), CDP (83.15 ± 26.19 and 98.62 ± 26.04), and LFC (0.16 ± 0.03 and 0.15 ± 0.03) were not significantly different (P > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02 and 0.75 ± 0.02), CDP (35.97 ± 25.79.10 and 143.80 ± 25.41), and LFC (0.09 ± 0.03 and 0.22 ± 0.03) were significantly different (P < 0.05). A similar trend was observed between the DP groups. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR, while they can significantly distinguish %AS and DP groups.
