Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model

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-m 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 Ͻ 120 and HR Ͼ 120 beats/min, %AS Ͻ 50 and %AS Ͼ 50, and additionally for DP Ͻ 14 and DP Ͼ 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 Ͻ 120 beats/min and HR Ͼ 120 beats/min groups, the values of FFR (0.82 Ϯ 0.02 and 0.82 Ϯ 0.02), CDP (83.15 Ϯ 26.19 and 98.62 Ϯ 26.04), and LFC (0.16 Ϯ 0.03 and 0.15 Ϯ 0.03) were not significantly different (P Ͼ 0.05). However, for %AS Ͻ 50 and %AS Ͼ 50, the FFR (0.89 Ϯ 0.02 and 0.75 Ϯ 0.02), CDP (35.97 Ϯ 25.79.10 and 143.80 Ϯ 25.41), and LFC (0.09 Ϯ 0.03 and 0.22 Ϯ 0.03) were significantly different (P Ͻ 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.

Functional diagnosis of coronary stenoses using pressure drop coefficient: A pilot study in humans

“…In our recent preclinical trials we have found that CDP is a promising clinical diagnostic parameter that can independently assess the severity of epicardial stenosis and microvascular impairment . Further, it was also reported in our recent studies that CDP is independent of variable hemodynamic conditions such as heart rate and contractility under both epicardial and microvascular impairment .…”

“…We have recently proposed and tested CDP, a nondimensional diagnostic parameter formulated based on fundamental fluid dynamic principles as a measure of stenosis severity in an animal model . CDP, by definition, combines both hyperemic pressure drop and velocity measurements.…”

Diagnostic Uncertainties During Assessment of Serial Coronary Stenoses: An In Vitro Study

“…CDP is defined as the ratio of the trans-stenotic pressure drop to the dynamic pressure proximal to a stenosis [22]. Simultaneous measurements of functional parameters (pressure drop and proximal velocity), necessary for the evaluation of CDP, can be readily obtained during routine cardiac catheterization procedures using a dual-sensor tipped guidewire, also known as a combowire [23][24][25][26][27]. CDP has been validated in pre-clinical trials [21,23,24,26,27] and under a clinical setting [25], in order to delineate epicardial stenoses.…”

“…Simultaneous measurements of functional parameters (pressure drop and proximal velocity), necessary for the evaluation of CDP, can be readily obtained during routine cardiac catheterization procedures using a dual-sensor tipped guidewire, also known as a combowire [23][24][25][26][27]. CDP has been validated in pre-clinical trials [21,23,24,26,27] and under a clinical setting [25], in order to delineate epicardial stenoses. Furthermore, it has been shown to be independent of heart rate [24,26] and contractility [27,28] in recently conducted in vivo animal studies.…”

“…CDP has been validated in pre-clinical trials [21,23,24,26,27] and under a clinical setting [25], in order to delineate epicardial stenoses. Furthermore, it has been shown to be independent of heart rate [24,26] and contractility [27,28] in recently conducted in vivo animal studies. CDP is known to have a large range of values comprising a lower and upper limit of 0 and 1000.…”