Background. Diagnosis of ischemic power of epicardial stenosis with concomitant microvas-cular disease (MVD) is challenging during coronary interventions, especially under variable he-modynamic factors like heart rate (HR). The goal of this study is to assess the influence of vari-able HR and %area stenosis (%AS), in the presence of MVD on pressure drop coefficient (CDP: ratio of trans-stenotic 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. Methods. %AS and MVD were created using angioplasty balloons and 90 µm microspheres, re-spectively. 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 >120 bpm, %AS < 50 and > 50 and additionally for DP < 14 and >14 mmHg, and analyzed using regression and ANOVA analysis. Results. 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 analy-sis, for the HR < 120 bpm and > 120 bpm groups, the values of FFR (0.82 ± 0.02, 0.82 ± 0.02), CDP (83.15 ± 26.19, 98.62 ± 26.04) and LFC (0.16 ± 0.03, 0.15 ± 0.03) were not significantly different (p > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02, 0.75 ± 0.02), CDP (35.97 ± 25.79.10, 143.80 ± 25.41) and LFC (0.09 ± 0.03, 0.22 ± 0.03), were significantly different (p < 0.05). A similar trend was observed between the DP groups. Conclusion. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR while they can significantly distinguish %AS and DP groups.
- microvascular disease
- Coronary diagnostic parameters
- CDP, LFC
- heart rate
- Copyright © 2011, American Journal of Physiology - Heart and Circulatory Physiology