scholarly journals A novel method for measuring absolute coronary blood flow and microvascular resistance in patients with ischaemic heart disease

2020 ◽  
Author(s):  
Paul D Morris ◽  
Rebecca Gosling ◽  
Iwona Zwierzak ◽  
Holli Evans ◽  
Louise Aubiniere-Robb ◽  
...  
Keyword(s):  
Blood Flow ◽  
Heart Disease ◽  
Coronary Flow ◽  
Microvascular Disease ◽  
Flow Reserve ◽  
Catheter Laboratory ◽  
Novel Method ◽  
Microvascular Resistance

Abstract Aims Ischaemic heart disease is the reduction of myocardial blood flow, caused by epicardial and/or microvascular disease. Both are common and prognostically important conditions, with distinct guideline-indicated management. Fractional flow reserve (FFR) is the current gold-standard assessment of epicardial coronary disease but is only a surrogate of flow and only predicts percentage flow changes. It cannot assess absolute (volumetric) flow or microvascular disease. The aim of this study was to develop and validate a novel method that predicts absolute coronary blood flow and microvascular resistance (MVR) in the catheter laboratory. Methods and results A computational fluid dynamics (CFD) model was used to predict absolute coronary flow (QCFD) and coronary MVR using data from routine invasive angiography and pressure-wire assessment. QCFD was validated in an in vitro flow circuit which incorporated patient-specific, three-dimensional printed coronary arteries; and then in vivo, in patients with coronary disease. In vitro, QCFD agreed closely with the experimental flow over all flow rates [bias +2.08 mL/min; 95% confidence interval (error range) −4.7 to +8.8 mL/min; R2 = 0.999, P < 0.001; variability coefficient <1%]. In vivo, QCFD and MVR were successfully computed in all 40 patients under baseline and hyperaemic conditions, from which coronary flow reserve (CFR) was also calculated. QCFD-derived CFR correlated closely with pressure-derived CFR (R2 = 0.92, P < 0.001). This novel method was significantly more accurate than Doppler-wire-derived flow both in vitro (±6.7 vs. ±34 mL/min) and in vivo (±0.9 vs. ±24.4 mmHg). Conclusions Absolute coronary flow and MVR can be determined alongside FFR, in absolute units, during routine catheter laboratory assessment, without the need for additional catheters, wires or drug infusions. Using this novel method, epicardial and microvascular disease can be discriminated and quantified. This comprehensive coronary physiological assessment may enable a new level of patient stratification and management.

Quantifying coronary microvascular disease: assessing absolute microvascular resistance reserve (MRR) by continuous coronary thermodilution

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
E Gallinoro ◽  
I Colaiori ◽  
G Di Gioia ◽  
S Fournier ◽  
M Kodeboina ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Infusion Rate ◽  
Guide Wire ◽  
Microvascular Disease ◽  
Individual Values ◽  
Flow Reserve ◽  
Absolute Flow ◽  
Significant Difference ◽  
Microvascular Resistance

Abstract Background and aim Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing whether continuous thermodilution can also measure resting flow and microvascular resistance. Methods and results In 87 coronary arteries (58 patients) with angiographic non-significant stenoses absolute flow was assessed by continuous thermodilution of saline at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. In addition, in 26 arteries, average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire. There was no significant difference between Pd/Pa at baseline and during saline infusion at 10 mL/min, (0.95±0.053 vs 0.94±0.054, respectively (p=0.53) and there was no significant difference in APV at baseline and during the infusion of saline at 10 mL/min (22.2±8.40 vs 23.2±8.39 cm/s, respectively, p=0.63), thus indicating presence of resting coronary blood flow during the infusion of 10 mL/min of saline. In contrast, at an infusion rate of 20 mL/min, a significant decrease in Pd/Pa was observed compared to baseline: (0.85±0.089 vs 0.95±0.053, respectively, p<0.001) and a significant increase in APV was observed (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) calculated by thermodilution and by Doppler flow velocity were similar (2.73±0.85 vs 2.72±1.07, respectively) and their individual values correlated closely (r=0.87, 95% CI 0.72–0.94, p<0,001). Microvascular resistance (Rμ), defined as the distal coronary pressure divided by the absolute flow was calculated both at rest (Rμ-rest) and during hyperemia (Rμ-hyper). Microvascular Resistance Reserve (MRR), is calculated as the ratio of Rμ-rest and Rμ-hyper and showed a good correlation with the analogous Doppler-derived parameter (using the APV instead of absolute flow). Mean doppler and thermodilution derived MRR were similar (3.32±1.50 vs 3.23±1.16) and values correlated closely (r=0.91, 95% CI 0.81 - 0.96, p<0.001; Bland-Altman analysis: mean bias = 0.071, limit of agreement −1.195 to 1.338). Conclusion Absolute coronary blood flow (in mL/min) can be measured by continuous thermodilution both at rest and during hyperemia. This allows accurate, reproducible, and operator-independent direct volumetric calculation of CFR and MRR. The latter is a quantitative metric which is specific for microvascular function and independent from myocardial mass. Doppler and Thermodilution derived MRR Funding Acknowledgement Type of funding source: None

scholarly journals A validated predictive model of coronary fractional flow reserve

2011 ◽  
Vol 9 (71) ◽  
pp. 1325-1338 ◽  
Author(s):  
Yunlong Huo ◽  
Mark Svendsen ◽  
Jenny Susana Choy ◽  
Z.-D. Zhang ◽  
Ghassan S. Kassab
Keyword(s):  
Analytical Model ◽  
Fractional Flow Reserve ◽  
Coronary Stenosis ◽  
Coronary Flow ◽  
Energy Losses ◽  
Fractional Flow ◽  
Conservation Of Energy ◽  
Flow Reserve

Myocardial fractional flow reserve (FFR), an important index of coronary stenosis, is measured by a pressure sensor guidewire. The determination of FFR, only based on the dimensions (lumen diameters and length) of stenosis and hyperaemic coronary flow with no other ad hoc parameters, is currently not possible. We propose an analytical model derived from conservation of energy, which considers various energy losses along the length of a stenosis, i.e. convective and diffusive energy losses as well as energy loss due to sudden constriction and expansion in lumen area. In vitro (constrictions were created in isolated arteries using symmetric and asymmetric tubes as well as an inflatable occluder cuff) and in vivo (constrictions were induced in coronary arteries of eight swine by an occluder cuff) experiments were used to validate the proposed analytical model. The proposed model agreed well with the experimental measurements. A least-squares fit showed a linear relation as (Δ p or FFR) experiment = a (Δ p or FFR) theory + b , where a and b were 1.08 and −1.15 mmHg ( r 2 = 0.99) for in vitro Δ p , 0.96 and 1.79 mmHg ( r 2 = 0.75) for in vivo Δ p , and 0.85 and 0.1 ( r 2 = 0.7) for FFR. Flow pulsatility and stenosis shape (e.g. eccentricity, exit angle divergence, etc.) had a negligible effect on myocardial FFR, while the entrance effect in a coronary stenosis was found to contribute significantly to the pressure drop. We present a physics-based experimentally validated analytical model of coronary stenosis, which allows prediction of FFR based on stenosis dimensions and hyperaemic coronary flow with no empirical parameters.

scholarly journals Relationship between capillary blood flow parameters measured in vivo and microrheologic parameters of blood measured in vitro in arterial hypertension and coronary heart disease

2021 ◽  
Vol 20 (1) ◽  
pp. 17-24
Author(s):  
I. M. Kadanova ◽  
A. I. Neznanov ◽  
A. Е. Lugovtsov ◽  
Yu. I. Gurfinkel ◽  
A. A. Pigurenko ◽  
...  
Keyword(s):  
Coronary Heart Disease ◽  
Blood Flow ◽  
Heart Disease ◽  
Capillary Blood ◽  
Control Group ◽  
Aggregation Index ◽  
Flow Parameters ◽  
Rbc Aggregation

Introduction. Blood microcirculation and its microrheologic properties are impaired in cardiovascular diseases. Microrheologic properties are characterized by the red blood cells (RBC) ability to aggregate and disaggregate. Therefore, the correlation studies between RBC aggregation and microcirculation disorders in pathologies are of interest for the development of theoretical concepts related to blood flow and for clinical practice.Aim. To analyze the correlation between capillary blood flow parameters measured in vivo and microrheologic blood parameters measured in vitro in patients suffering arterial hypertension (AH) and coronary heart disease (CHD).Materials and methods. We studied 3 groups of people: patients suffering AH, patients suffering AH+CHD and healthy donors. The characteristic aggregation time and aggregation index were measured in vitro by laser aggregometry. Analysis of capillary blood velocity (CBV) and assessment of the presence and absence of RBC aggregates in the nail bed capillaries were performed in vivo using vital digital capillaroscopy (VDC).Results. RBC aggregation for groups of patients suffering AH and AH+CHD was increased compared to the control group. Thus, in these patients groups, the characteristic aggregation time significantly decreases by an average of (38±13) %. Comparison of the results obtained using in vitro and in vivo methods showed the aggregation index for individuals with high CBV was significantly lower than for individuals with low CBV. The tendency is that the number of aggregates in the capillaries increases with a decrease in CBV.Conclusion. RBC aggregation is increased in groups of patients suffering AH and AH+CHD compared to the control group. The correlation between parameters measured in vitro and in vivo is evident for patients divided into subgroups according to parameters measured using the VDC. The obtained results allow us to conclude that the used methods are applicable in clinical practice.

scholarly journals Early Hyperdynamic Sepsis Alters Coronary Blood Flow Regulation in Porcine Fecal Peritonitis

2021 ◽  
Vol 12 ◽  
Author(s):  
Céline Boudart ◽  
Fuhong Su ◽  
Lorenzo Pitisci ◽  
Arnaud Dhoine ◽  
Olivier Duranteau ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Ex Vivo ◽  
Flow Regulation ◽  
Flow Reserve ◽  
Vasodilatory Response ◽  
Blood Flow Regulation ◽  
Microvascular Resistance ◽  
Hyperdynamic Sepsis

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis.Methods: Fourteen pigs were randomized to sham (n = 7) or fecal peritonitis-induced sepsis (n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation.Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I2 receptor, and prostaglandin F2α receptor.Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved.

scholarly journals Thermodilution-Based Invasive Assessment of Absolute Coronary Blood Flow and Microvascular Resistance: Quantification of Microvascular (Dys)Function?

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Daniëlle C. J. Keulards ◽  
Mohamed El Farissi ◽  
Pim. A. L Tonino ◽  
Koen Teeuwen ◽  
Pieter-Jan Vlaar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Microvascular Disease ◽  
Small Vessels ◽  
Flow Reserve ◽  
Positron Emission ◽  
Golden Standard ◽  
Long Term Follow Up ◽  
Index Of Microvascular Resistance ◽  
Microvascular Resistance

During the last two decades, there has been a sharp increase in both interest and knowledge about the coronary microcirculation. Since these small vessels are not visible by the human eye, physiologic measurements should be used to characterize their function. The invasive methods presently used (coronary flow reserve (CFR) and index of microvascular resistance (IMR)) are operator-dependent and mandate the use of adenosine to induce hyperemia. In recent years, a new thermodilution-based method for measurement of absolute coronary blood flow and microvascular resistance has been proposed and initial procedural problems have been overcome. Presently, the technique is easy to perform using the Rayflow infusion catheter and the Coroventis software. The method is accurate, reproducible, and completely operator-independent. This method has been validated noninvasively against the current golden standard for flow assessment: Positron Emission Tomography-Computed Tomography (PET-CT). In addition, absolute flow and resistance measurements have proved to be safe, both periprocedurally and at long-term follow-up. With an increasing number of studies being performed, this method has great potential for better understanding and quantification of microvascular disease.

scholarly journals 389 Microvascular dysfunction in patients with Type II diabetes mellitus: invasive assessment of absolute coronary blood flow and microvascular resistance reserve

2021 ◽  
Vol 23 (Supplement_G) ◽  
Author(s):  
Pasquale Paolisso ◽  
Emanuele Gallinoro ◽  
Alessandro Candreva ◽  
Konstantinos Bermpeis ◽  
Davide Fabbricatore ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diastolic Dysfunction ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Microvascular Dysfunction ◽  
Microvascular Function ◽  
Diabetic Patients ◽  
Flow Reserve ◽  
Significant Difference ◽  
Microvascular Resistance

Abstract Aims Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups. Methods In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperaemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction. Results The median FFR value was 0.83 (0.79–0.87) without any significant difference between the two groups. Absolute resting and hyperaemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperaemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group [CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, (P < 0.05 for both)]. Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all P < 0.05). Conclusions Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperaemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

scholarly journals Improvement of Fractional Flow Reserve after Percutaneous Coronary Intervention Does Not Necessarily Indicate Increased Coronary Flow

2019 ◽  
Vol 14 (1) ◽  
pp. 10-12 ◽  
Author(s):  
Rikuta Hamaya ◽  
Yoshihisa Kanaji ◽  
Eisuke Usui ◽  
Masahiro Hoshino ◽  
Tadashi Murai ◽  
...  
Keyword(s):  
Blood Flow ◽  
Percutaneous Coronary Intervention ◽  
Coronary Blood Flow ◽  
Fractional Flow Reserve ◽  
Coronary Flow ◽  
Coronary Intervention ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Percutaneous Coronary ◽  
Microvascular Resistance

Coronary flow is expected to increase by epicardial lesion modification after successful percutaneous coronary intervention (PCI) in stable angina. According to the concept of fractional flow reserve (FFR), the improvement in FFR after PCI reflects the extent of coronary flow increase. However, this theory assumes that hyperaemic microvascular resistance does not change after PCI, which is being refuted in recent studies. The authors quantitated regional absolute coronary blood flow (ABF) before and after PCI using a thermodilution method and compared it with FFR in 28 patients with stable coronary artery disease who had undergone successful PCI. Although FFR indicated changes in ABF, with a mean difference of −5.5 ml/min, there was no significant relationship between individual changes in FFR and in ABF (R=0.27, p=0.16). The discrepancy was partly explained by changes in microvascular resistance following PCI. These results suggest that changes in FFR do not necessarily indicate an increase in absolute coronary blood flow following PCI in individual patients, although they could be correlated in a cohort level.

Effect of caffeine on theophyliine on cerebral blood flow response to brain activation: In vitro and in vivo studies

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S198-S198
Author(s):  
Joseph R Meno ◽  
Thien-son K Nguyen ◽  
Elise M Jensen ◽  
G Alexander West ◽  
Leonid Groysman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Activation ◽  
In Vivo Studies ◽  
Blood Flow Response ◽  
Flow Response
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