Coronary Artery Flow Reserve Research Articles

Comparing Pressure-Bounded Versus Thermodilution-Derived Coronary Flow Reserve in Unobstructed Coronary Arteries

Comparing Pressure-Bounded Versus Thermodilution-Derived Coronary Flow Reserve in Unobstructed Coronary Arteries

Ticagrelor Treatment is Associated With Increased Coronary Flow Reserve in Survivors of Myocardial Infarction.

The pleiotropic action of ticagrelor, with effects in addition to platelet inhibition, has been shown to improve endothelial function in patients with coronary artery disease. These positive effects are possibly adenosine mediated. This study investigated the association of ticagrelor therapy and coronary artery flow reserve in survivors of myocardial infarction (MI). This was an exploratory, cross-sectional, open substudy of PROFLOW. High-risk individuals with a history of MI were identified. Coronary flow reserve (CFR) was measured non-invasively in the left anterior descending artery using transthoracic Doppler echocardiography. Coronary flow velocity was measured at rest and at maximal flow after induction of hyperaemia by intravenous infusion of adenosine at 140 μg/kg/min. Patients receiving ticagrelor (n=75) were compared with those not receiving ticagrelor (n=506), using simple and multiple linear regression models. Most patients in both groups were treated with aspirin (97% in the ticagrelor and 94% in the non-ticagrelor group). Adjustment for traditional risk factors was conducted. The mean age at study inclusion was 68.5±6.8 years, and most patients were male (81.8%). The simple linear regression analysis showed ticagrelor treatment to be significantly associated with increased CFR: ticagrelor 2.95±0.76 (mean±SD), non-ticagrelor 2.70±0.77, (coefficient 0.25; 95% CI 0.063-0.438; p=0.009). This association was significant in two of the three multiple linear regression models with increasing numbers of variables: Model 1 (0.28; 0.06-0.50; p=0.014), Model 2 (0.26; 0.03-0.48; p=0.025), and borderline significant in Model 3 (0.21; -0.01 to 0.43; p=0.058). Ticagrelor treatment was associated with increased CFR in this high-risk population. Increased CFR may be a clinically important therapeutic effect of ticagrelor in addition to platelet inhibition.

Anomalous origin of the left coronary artery in patient with reduction of right coronary artery flow reserve detected by CZT camera

Anomalous origin of the left coronary artery in patient with reduction of right coronary artery flow reserve detected by CZT camera

A fast algebraic approach for noninvasive prediction of fractional flow reserve in coronary arteries

The fractional flow reserve (FFR) index is an important clinical indicator for characterizing coronary artery disease (CAD) functional significance, allowing cardiologists to decide whether intervention is required or not. Noninvasive techniques for calculating FFR are still incompletely resolved and rely heavily on time consuming numerical methods, which may hinder their clinical translation. This paper reports on the development of two fast and noninvasive methods for predicting FFR in diseased coronary arteries. The new methods are derived from physical principles and account for patient-specific physiological parameters that can be noninvasively measured. The developed algebraic equations calculate FFR without performing any tedious numerical simulations, making them attractive for clinical applications. The performance of the methods is assessed by comparing their predictions with measurements and with results obtained by full three-dimensional numerical simulations on healthy and diseased idealized coronary arteries and actual anatomical branches. Results generated by the new methodology are within 5% of measurements and in very good agreement with values obtained numerically.

Impact of clinical and haemodynamic factors on coronary flow reserve and invasive coronary flow capacity in non-obstructed coronary arteries: a patient-level pooled analysis of the DEBATE and ILIAS studies.

Coronary flow reserve (CFR) is a physiological index for the assessment of myocardial flow impairment due to focal or microcirculatory coronary artery disease (CAD). Coronary flow capacity (CFC) is another flow-based concept in diagnosing ischaemic heart disease, based on hyperaemic average peak velocity (hAPV) and CFR. We evaluated clinical and haemodynamic factors which potentially influence CFR and CFC in non-obstructed coronary arteries. Intracoronary Doppler flow velocity measurements to obtain CFR and CFC were performed after inducing hyperaemia in 390 non-obstructed vessels of patients who were scheduled for elective percutaneous coronary intervention (PCI) of another vessel. Akaike's information criterion (AIC) revealed age, female gender, history of myocardial infarction, hypercholesterolaemia, diastolic blood pressure, oral nitrates and rate pressure product as independent predictors of CFR and CFC. After regression analysis, age and female gender were associated with lower CFR and age was associated with worse CFC in angiographically non-obstructed vessels. Age and female gender are associated with lower CFR, and age with worse CFC in an angiographically non-obstructed coronary artery. CFC seems to be less sensitive to variations in clinical and haemodynamic parameters than CFR and is therefore a promising tool in contemporary clinical decision making in the cardiac catheterisation laboratory.

Use of Ranolazine for the Treatment of Coronary Microvascular Dysfunction.

Coronary microvascular dysfunction (CMD) is defined as a mismatch of myocardial blood supply and oxygen consumption due to a dysfunction of the coronary microvessels. Up to 20-30% of patients with CMD have progressive worsening of symptoms with significant impairment of quality of life. Large-scale randomized studies of the pharmacologic treatment of CMD are lacking. Classic anti-ischemic drugs are the initial form of treatment, but efficacy is often limited. Ranolazine has a unique mechanism of action that does not affect blood pressure or heart rate. When added to existing anti-anginal agents, ranolazine improved at least one domain in eight of ten studies in which a questionnaire was used to assess patient health status. Five studies evaluated coronary arterial flow reserve (CFR), reporting that patients with low values had significant improvement in CFR and suggesting that those with more severe CMD respond more favorably to ranolazine. In two studies, exercise duration and time to myocardial ischemia were significantly increased after treatment with ranolazine. Data are lacking for ranolazine use as the sole agent for CMD treatment. Some questions remain to be answered regarding ranolazine use for CMD. Larger studies of longer duration are needed to verify the effectiveness of ranolazine in the treatment of CMD.

Global Coronary Artery Flow Reserve after Heart Transplantation: Recipient or Donor Age-Driven?

Cardiac allograft vasculopathy (CAV) remains a vexing problem limiting survival beyond the early post-transplant years. While global coronary artery flow reserve (CFR) may detect early CAV, standard "norms" have not yet been established in heart transplant recipients (HTR). It is further unsettled whether these CFR should be based on recipient or donor age. The recipient-donor age mismatch in HTR provides a unique opportunity for such study using cardiac stress PET (CPET). The CPET database at Intermountain Medical Center was queried for HTR with normal coronary arteries (CAV0). CFR were derived from the CPET preceding the normal coronary angiograms. The study group was age and gender-matched in a 1:2 fashion to a control group of non-transplant patients with normal CPET and coronary arteries. 36 HTR and 72 controls were eligible for inclusion. Average recipient age was 60 ± 13 years, 81% were male; average donor age was 34 ± 9 years, 78% were male; average time-since-transplant was 9 ± 2 years. The mean CFR (ml/g/min) of HTR and controls were 2.39±0.8 and 2.45±0.84 (p= 0.72)respectively. Results are shown in the figure below. Our study suggests that the CFR for HTR match the expected values in non-transplant controls when based on recipient age. Hence it is reasonable to use the normal CFR range of general population as reference in HTR. That the CFR in HTR is recipient rather than donor age-driven is most intriguing and deserves further investigation.

A clinical study on the effect of open chronic total occlusion on hemodynamics of collateral circulation donor.

This study applied pressure measurement to measure the hemodynamic changes in right coronary artery (RCA) donor vessels before and after the opening of the vessel in patients with left anterior descending chronic total occlusion (LAD-CTO) interventional therapy. A total of 45 patients with LAD-CTO were divided into two groups of percutaneous coronary intervention (PCI) to observe the hemodynamic changes (fractional flow reserve [FFR] and instantaneous wave-free ratio [iFR]) before and after opening the chronic total occlusion (CTO), in order to provide collateral circulating donor vessels to the CTO, and observe the changes in iFR and FFR. The results of these two measures were compared to determine the significance of the donor vascular function. A total of 45 patients with LAD-CTO successfully underwent LAD-CTO interventional therapy, and were immediately measured for FFR and iFR of the donor vessels. The FFR changes before right coronary artery flow reserve (RCAFR) was 0.73±0.083, and after the operation, this was 0.77±0.073. The iFR changes before RCAFR was 0.90±0.048, and after the operation, this was 0.93±0.034. Before and after the opening of the RCA, the FFR change (ΔFFR) and iFR change (ΔiFR) were also correlated with r = 0.033 (0.041-0.568: P < 0.05). A total of 19 cases had a FFR value of <0.75 before the operation, and the average FFR before and after the PCI was 0.65±0.048 and 0.72±0.057, respectively. Furthermore, the ΔFFR was 0.076±0.057 (n = 19), and FFR was >0.75 in 26 cases. The ΔFFR was 0.017±0.0088 (n = 26). These two groups were compared, P = 0.0032 (P < 0.05). The FFR and iFR results were the same in terms of RCA hemodynamic changes, after the LAD-CTO was opened. For the RCA with a preoperative FFR of <0.75, the increase in RCAFR after LAD-CTO PCI was more obvious.

P5620Clinical and hemodynamic determinants of coronary flow reserve in non-obstructed coronary arteries - A patient level pooled analysis of the DEBATE and ILIAS studies

Abstract Aim Coronary Flow Reserve (CFR) is a valuable physiological index for the assessment of myocardial flow impairment due to focal or microcirculatory coronary artery disease (CAD). Coronary flow capacity (CFC) is another flow-based concept in diagnosing ischemic heart disease (IHD), based on hyperemic average peak velocity (hAPV) and CFR. We evaluated clinical and hemodynamic factors which potentially influence CFR and CFC in non-obstructed coronary arteries. Methods We analysed CFR and CFC of 396 non-obstructed vessels of patients from two large multi-center trials (DEBATE and ILIAS) with stable CAD who were scheduled for percutaneous coronary intervention (PCI). Doppler flow measurements were performed after inducing hyperemia with either intracoronary or intravenous infusion of adenosine. Results Akaike's Information Criterion (AIC) revealed the parameters age, female gender, a history of myocardial infarction, hypercholesterolemia, current or previous smoking and rate pressure product (RPP) as independent predictors in the best model of fit for CFR in an angiographically non-obstructed vessel. After multivariate regression analysis age, female gender and RPP remained as determinants of CFR in angiographically non-obstructed vessels. Subsequently, ordered logistic regression analysis revealed that age is associated with a worse CFC. Conclusion Clinical and hemodynamic parameters are associated with CFR and to a lesser extent CFC in an angiographically non-obstructed coronary artery. CFC is less sensitive to variations in clinical and hemodynamic parameters than CFR and therefore a promising tool in contemporary clinical decision making in the cardiac catheterization laboratory. Acknowledgement/Funding DEBATE: Cardiometrics INC. ILIAS: Dutch Health Insurance Board; RADI Medical Systems, Uppsala, Sweden; and Endosonics, Rancho Cordova, CA.

TCT-474 Impact of Clinical and Hemodynamic Factors on Coronary Flow Reserve and Invasive Coronary Flow Capacity in Nonobstructed Coronary Arteries: A Patient-Level Pooled Analysis of the DEBATE and ILIAS Studies

TCT-474 Impact of Clinical and Hemodynamic Factors on Coronary Flow Reserve and Invasive Coronary Flow Capacity in Nonobstructed Coronary Arteries: A Patient-Level Pooled Analysis of the DEBATE and ILIAS Studies

Impact of Pulmonary Venous Inflow on Cardiac Flow Simulations: Comparison with In Vivo 4D Flow MRI

Blood flow simulations are making their way into the clinic, and much attention is given to estimation of fractional flow reserve in coronary arteries. Intracardiac blood flow simulations also show promising results, and here the flow field is expected to depend on the pulmonary venous (PV) flow rates. In the absence of in vivo measurements, the distribution of the flow from the individual PVs is often unknown and typically assumed. Here, we performed intracardiac blood flow simulations based on time-resolved computed tomography on three patients, and investigated the effect of the distribution of PV flow rate on the flow field in the left atrium and ventricle. A design-of-experiment approach was used, where PV flow rates were varied in a systematic manner. In total 20 different simulations were performed per patient, and compared to in vivo 4D flow MRI measurements. Results were quantified by kinetic energy, mitral valve velocity profiles and root-mean-square errors of velocity. While large differences in atrial flow were found for varying PV inflow distributions, the effect on ventricular flow was negligible, due to a regularizing effect by mitral valve. Equal flow rate through all PVs most closely resembled in vivo measurements and is recommended in the absence of a priori knowledge.

An Outflow Boundary Condition Model for Noninvasive Prediction of Fractional Flow Reserve in Diseased Coronary Arteries.

This paper reports on a new boundary condition formulation to model the total coronary myocardial flow and resistance characteristics of the myocardial vascular bed for any specific patient when considered for noninvasive diagnosis of ischemia. The developed boundary condition model gives an implicit representation of the downstream truncated coronary bed. Further, it is based on incorporating patient-specific physiological parameters that can be noninvasively extracted to account for blood flow demand to the myocardium at rest and hyperemic conditions. The model is coupled to a steady three-dimensional (3D) collocated pressure-based finite volume flow solver and used to characterize the "functional significance" of a patient diseased coronary artery segment without the need for predicting the hemodynamics of the entire arterial system. Predictions generated with this boundary condition provide a deep understanding of the inherent challenges behind noninvasive image-based diagnostic techniques when applied to human diseased coronary arteries. The overall numerical method and formulated boundary condition model are validated via two computational-based procedures and benchmarked with available measured data. The newly developed boundary condition is used via a designed computational methodology to (a) confirm the need for incorporating patient-specific physiological parameters when modeling the downstream coronary resistance, (b) explain the discrepancies presented in the literature between measured and computed fractional flow reserve (FFRCT), and

CRT-100.55 Effect of Orbital Atherectomy and Adjunctive Stenting on Coronary Blood Flow

Reduced flow and no reflow are known complications associated with rotational atherectomy and attributed to dysfunction of the microcirculation. Coronary microcirculation dysfunction post-PCI can cause myocardial ischemia. Previous coronary artery flow reserve (CFR) studies on rotational atherectomy

Reversible myocardial perfusion defects in patients not suffering from obstructive epicardial coronary artery disease as assessed by coronary angiography.

In approximately 10-30% of patients presenting with angina complaints, normal or non-obstructive coronary arteries are found on angiography. In this review paper, available literature on the underlying pathophysiological substrate explaining these discrepancies is reviewed. Both histological studies as well as studies using intravascular ultrasound e.g. the PROSPECT trial, show that epicardial coronary vessel significant lumen stenosis may be delayed until a plaque occupies 40% of the internal elastic lamina area. Limited available data suggest that these angiographically undetectable plaques are associated with an abnormal vasodilation capacity of the coronary circulation and may results in reversible perfusion defects on myocardial perfusion imaging (MPI). Organic non-atherosclerotic causes of epicardial coronary artery disease such as anomalous coronary arteries that course between the aorta and pulmonary artery, myocardial bridging and coronary vasospasm may also contribute to MPI results suggesting the presence of ischemia in the presence of normal coronary arteries on coronary angiography. Additional causes of reversible perfusion defects on MPI in the presence of a normal coronary angiogram are intraventricular conduction disturbances. The existence of reversible perfusion defects in the anteroseptal region in most of the patients suffering from left bundle branch block (LBBB) on MPI following physical exercise as stressor is well documented. As the observed reduced septal uptake of both 201Tl and 99mTc-sestamibi/tetrofosmin in LBBB reflects coronary autoregulation in response to lower oxygen demands, not surprisingly, dipyridamole which uniformly exploits flow reserve, has proven more accurate for the diagnosis of coronary artery disease (CAD) in patients suffering from LBBB. Although patients with a permanent ventricular pacemaker have a similar conduction abnormality as patients presenting with a LBBB, most of the defects found on MPI imaging in this patient population (in up to 78% of patients with a normal coronary angiogram that area continuously paced) are localized in the inferoposterior (71%), apical (50%) and inferoseptal (28%) wall; coronary flow velocities in the left anterior descending (LAD) and dominant coronary artery and coronary flow reserve are also significantly lower when compared to a control group. Contrary to what is seen in LBBB patients, dipyridamole stress does not significantly reduce the incidence of abnormalities found but limits the defects to the inferior wall. Furthermore, the frequency of abnormalities found on MPI increases over time with right ventricular outflow tract pacing. Previous histologic studies have shown that microvessel disease is often accompanied by a slow-flow phenomenon reflecting decreased resting flow velocity. Thus, not surprisingly, MPI reversible abnormalities in the presence of a normal coronary angiogram have been reported in a wide variety of diseases characterized by microvessel disease such as diabetes, systemic lupus erythematosus, Behçet's disease and metabolic syndrome. In these patients, low adiponectin and high lipoprotein(a) levels are found which are known to be associated with endothelial dysfunction, atherosclerosis and coronary artery disease. Furthermore, in these patients, limited available data suggest that reversible perfusion defects on MPI confer a significantly poorer prognosis both in terms of hard event rate (MI and cardiac death) and total event rate (MI, cardiac death or late revascularization). It is thus suggested that MPI could discriminate patients with a more severe prognosis. Finally, physical training in patients with primary microvascular angina appears to be associated with reduction of myocardial perfusion abnormalities.

Three-dimensional modeling and numerical analysis of fractional flow reserve in human coronary arteries.

IntroductionNoninvasive fractional flow reserve (FFR) computed from CT (FFRCT) is a novel method for determining the physiologic significance of coronary artery disease (CAD). Several clinical trials have been conducted, but its diagnostic performance varied among different trials.AimTo determine the cut-off value of FFRCT and its correlation with the gold standard used to diagnose CAD in clinical practice.Material and methodsForty patients with single vessel disease were included in our study. Computed tomography scan and coronary angiography with FFR were conducted for these patients. Three-dimensional geometric reconstruction and numerical analysis based on the computed tomographic angiogram (CTA) of coronary arteries were applied to obtain the values of FFRCT. The correlation between FFRCT and the gold standard used in clinical practice was tested.ResultsFor FFRCT, the best cut-off value was 0.76, with the sensitivity, specificity, positive predictive value and negative predictive values of 84.6%, 92.9%, 88% and 73.3%, respectively. The area under the receiver-operator characteristics curve was 0.945 (p < 0.0001). There was a good correlation of FFRCT values with FFR values (r = 0.94, p < 0.0001), with a slight overestimation of FFRCT as compared with measured FFR (mean difference 0.01 ±0.11, p < 0.05). For inter-observer agreement, the mean κ value was 0.69 (0.61 to 0.78) and for intra-observer agreement the mean κ value was 0.61 (0.50 to 0.72).ConclusionsFFRCT derived from CT of the coronary artery is a reliable non-invasive way providing reliable functional information of coronary artery stenosis.

120 The Instantaneous Wave-Free Ratio (IFR) Is An Accurate Predictor of Fractional Flow Reserve (FFR) In Adult Coronary Arteries so Long As a Grey Zone or Hybrid-Approach is used and not Individual Cut-Offs: The Blackpool Coronary IFR (Bcis) Study

Background Fractional flow reserve (FFR) can be used in the cath lab to assess coronary arteries for ischaemia. To calculate an FFR adenosine needs to be given. The IFR (instantaneous free-wave ratio) has been mooted as an adenosine-independent cath-lab measure of ischaemia, derived using coronary artery wave-intensity analysis. Once validated it may thus reduce patient discomfort and procedural cost. Two approaches have been mooted when using iFR namely a) a single cut-off (iFR 0.93 normal and iFR 0.86–0.93 borderline). In borderline cases adenosine should be given and FFR calculated instead. No study has prospectively assessed these two approaches to assess the validity of iFR in predicting FFR. Methods Consecutive patients undergoing an FFR study in the cath lab underwent an iFR measurement first. Two iFR measurements were taken in the first 25 cases to assess iFR reproducibility. Adenosine was then given in all cases and an FFR was measured. The patients were managed according to the FFR result. Two iFR approaches were compared: a) a single cut-off of iFR 0.93 normal. Results In a preliminary analysis (more data will be available for the meeting), data was collected in 20 patients (12 men (60%), mean age 63 years (range 47–87)) and 41 coronary arteries. Mean FFR was 0.84 (range 0.55–0.98). 13 arteries (32%) had an abnormal FFR ( 0.93, and 16 (39%) iFR 0.86–0.93 (borderline). Of the 16 borderline cases, 7 (44%) had FFR < = 0.80. iFR was highly reproducible with 95% limits of agreement +0.01 to – 0.015. The correlation between iFR and FFR was excellent with R2 0.76. The sensitivity, specificity, PPV, NPV, overall accuracy and Kappa value of agreement comparing single cut-off vs hybrid approach were 53% vs 92%; 89% vs 100%; 70% vs 100%; 81% vs 97%, 78% vs 98%, and 0.46 vs 0.94 respectively. Thus the hybrid approach was superior at each value. Conclusions iFR measurements are quick to obtain and highly reproducible. iFR showed excellent correlation with FFR. There was only 78% agreement between iFR and FFR when using a single cut-off approach. This improved to 98% when using the hybrid approach. This approach consists of only giving adenosine and measuring FFR for borderline iFR values (iFR 0.86–0.93). Higher iFR values (>0.93) can be taken as normal and lower iFR values (<0.86) can be taken as abnormal. There was a false positive rate of only 3% and a false negative rate of 0% using the hybrid approach. 61% of cases fell outside the grey zone in consecutive patients and thus adenosine use could potentially be reduced by 61% and accuracy maintained if using the iFR and hybrid approach.

Ultrasound based assessment of coronary artery flow and coronary flow reserve using the pressure overload model in mice.

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow reserve (CFR) in humans. Reduced CFR is accompanied by marked intramyocardial and pericoronary fibrosis and is used as an indication of the severity of dysfunction. This study explores, step-by-step, the real-time changes measured in the coronary flow velocity, CFR and systolic to diastolic peak velocity (S/D) ratio in the setting of an aortic banding model in mice. By using a Doppler transthoracic imaging technique that yields reproducible and reliable data, the method assesses changes in flow in the septal coronary artery (SCA), for a period of over two weeks in mice, that previously either underwent aortic banding or thoracotomy. During imaging, hyperemia in all mice was induced by isoflurane, an anesthetic that increased coronary flow velocity when compared with resting flow. All images were acquired by a single imager. Two ratios, (1) CFR, the ratio between hyperemic and baseline flow velocities, and (2) systolic (S) to diastolic (D) flow were determined, using a proprietary software and by two independent observers. Importantly, the observed changes in coronary flow preceded LV dysfunction as evidenced by normal LV mass and fractional shortening (FS). The method was benchmarked against the current gold standard of coronary assessment, histopathology. The latter technique showed clear pathologic changes in the coronary artery in the form of peri-coronary fibrosis that correlated to the flow changes as assessed by echocardiography. The study underscores the value of using a non-invasive technique to monitor coronary circulation in mouse hearts. The method minimizes redundant use of research animals and demonstrates that advanced ultrasound-based indices, such as CFR and S/D ratios, can serve as viable diagnostic tools in a variety of investigational protocols including drug studies and the study of genetically modified strains.

Ultrasound Based Assessment of Coronary Artery Flow and Coronary Flow Reserve Using the Pressure Overload Model in Mice

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow reserve (CFR) in humans. Reduced CFR is accompanied by marked intramyocardial and pericoronary fibrosis and is used as an indication of the severity of dysfunction. This study explores, step-by-step, the real-time changes measured in the coronary flow velocity, CFR and systolic to diastolic peak velocity (S/D) ratio in the setting of an aortic banding model in mice. By using a Doppler transthoracic imaging technique that yields reproducible and reliable data, the method assesses changes in flow in the septal coronary artery (SCA), for a period of over two weeks in mice, that previously either underwent aortic banding or thoracotomy. During imaging, hyperemia in all mice was induced by isoflurane, an anesthetic that increased coronary flow velocity when compared with resting flow. All images were acquired by a single imager. Two ratios, (1) CFR, the ratio between hyperemic and baseline flow velocities, and (2) systolic (S) to diastolic (D) flow were determined, using a proprietary software and by two independent observers. Importantly, the observed changes in coronary flow preceded LV dysfunction as evidenced by normal LV mass and fractional shortening (FS). The method was benchmarked against the current gold standard of coronary assessment, histopathology. The latter technique showed clear pathologic changes in the coronary artery in the form of peri-coronary fibrosis that correlated to the flow changes as assessed by echocardiography. The study underscores the value of using a non-invasive technique to monitor coronary circulation in mouse hearts. The method minimizes redundant use of research animals and demonstrates that advanced ultrasound-based indices, such as CFR and S/D ratios, can serve as viable diagnostic tools in a variety of investigational protocols including drug studies and the study of genetically modified strains.

Patient-specific anatomical models in human physiology

AbstractPatient-specific simulations of human physiological processes remain the challenge for many years. Detailed 3D reconstruction of body anatomical parts on the basis of medical images is an important stage of individualized simulations in physiology. In this paper we present and develop the methods and algorithms for construction of patient-specific discrete geometric models. These models are represented by anatomically correct computational meshes. Practical use of these methods is demonstrated for two important medical applications: numerical evaluation of fractional flow reserve in coronary arteries and electrocardiography simulation

Influence of the length of coronary artery lesions on fractional flow reserve across intermediate coronary obstruction

The aim of the study was to assess the effect of coronary lesion length (LL) on fractional flow reserve (FFR) in coronary arteries with intermediate diameter stenosis (DS; 30– 60%). Eighty-three patients (89 lesions) with coronary artery disease underwent FFR measurement using a Radi or Volcano pressure wire. Diameter stenosis and LL were determined by quantitative coronary angiography, and the relationship between DS, LL, and FFR was assessed by regression analysis. Seventy-nine lesions had DS between 30 and 60% and were entered into the retrospective analysis. Mean DS and LL were 41.6 (+6.77%) and 9.2 (+6 mm), respectively. Fractional flow reserve ranged from 0.5 to 1.0. Pearson correlation coefficient for FFR vs. LL was 0.42 (P , 0.001). Using FFR ¼ 0.8 as a cut-off point, there was no difference in mean DS between the two subgroups (42 vs. 41.5%, P ¼ NS), while there was a significant difference in the LL (12.39 vs. 7.83 mm, P ¼ 0.002). In intermediate coronary artery lesion, there is a strong inverse correlation between FFR and LL.