Influence of contractility and heart rate on pressure drop coefficient and fractional flow reserve for epicardial stenosis

American Journal of Physiology-Heart and Circulatory Physiology

Banerjee

Kolli

et al. 2012

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.

“…From Fig. 9A, it can be seen that FFR cannot delineate between ES and MVD, a conclusion similar to previous studies (17,18,20,28,29,38,41). However, the other two parameters, CDP (Fig.…”

Section: Discussionsupporting

confidence: 88%

“…9B) and LFC (Fig. 9C), can delineate the presence of MVD and ES, similar to previous studies in a porcine model (4,20,40). It can be seen that there is an overlap in the error bars.…”

Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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

American Journal of Physiology-Heart and Circulatory Physiology

Banerjee

Kolli

et al. 2012

“…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.…”

Section: Introductionmentioning

confidence: 98%

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

D’Souza

Journal of Biomechanical Engineering

Banerjee

2014

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Currently, the diagnosis of coronary stenosis is primarily based on the well-established functional diagnostic parameter, fractional flow reserve (FFR: ratio of pressures distal and proximal to a stenosis). The threshold of FFR has a "gray" zone of 0.75-0.80, below which further clinical intervention is recommended. An alternate diagnostic parameter, pressure drop coefficient (CDP: ratio of trans-stenotic pressure drop to the proximal dynamic pressure), developed based on fundamental fluid dynamics principles, has been suggested by our group. Additional serial stenosis, present downstream in a single vessel, reduces the hyperemic flow, Q˜h, and pressure drop, Δp˜, across an upstream stenosis. Such hemodynamic variations may alter the values of FFR and CDP of the upstream stenosis. Thus, in the presence of serial stenoses, there is a need to evaluate the possibility of misinterpretation of FFR and test the efficacy of CDP of individual stenoses. In-vitro experiments simulating physiologic conditions, along with human data, were used to evaluate nine combinations of serial stenoses. Different cases of upstream stenosis (mild: 64% area stenosis (AS) or 40% diameter stenosis (DS); intermediate: 80% AS or 55% DS; and severe: 90% AS or 68% DS) were tested under varying degrees of downstream stenosis (mild, intermediate, and severe). The pressure drop-flow rate characteristics of the serial stenoses combinations were evaluated for determining the effect of the downstream stenosis on the upstream stenosis. In general, Q˜h and Δp˜ across the upstream stenosis decreased when the downstream stenosis severity was increased. The FFR of the upstream mild, intermediate, and severe stenosis increased by a maximum of 3%, 13%, and 19%, respectively, when the downstream stenosis severity increased from mild to severe. The FFR of a stand-alone intermediate stenosis under a clinical setting is reported to be ∼0.72. In the presence of a downstream stenosis, the FFR values of the upstream intermediate stenosis were either within (0.77 for 80%-64% AS and 0.79 for 80%-80% AS) or above (0.88 for 80%-90% AS) the "gray" zone (0.75-0.80). This artificial increase in the FFR value within or above the "gray" zone for an upstream intermediate stenosis when in series with a clinically relevant downstream stenosis could lead to misinterpretation of functional stenosis severity. In contrast, a distinct range of CDP values was observed for each case of upstream stenosis (mild: 8-10; intermediate: 47-54; and severe: 130-155). The nonoverlapping range of CDP could better delineate the effect of the downstream stenosis from the upstream stenosis and allow for the accurate diagnosis of the functional severity of the upstream stenosis.

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

Kolli

Helmy

Cathet Cardio Intervent

et al. 2013

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