Left Coronary Bifurcation Research Articles

DES Selection for Left Main and Coronary Bifurcation Stenting.

Coronary bifurcation lesions present a challenging lesion subset regarding procedural complexity and worse patient outcomes as compared to simple lesions. Drug eluting stents (DES), as the current standard of care for percutaneous myocardial revascularization, have tubular design and uniform diameter, and therefore, need to be subjected to a standardized set of procedural modifications, to optimally fit and reconstruct underlying bifurcation anatomy. Since contemporary DES have various design platforms, with diverse mechanical properties, we must be aware of the device's favorable characteristics and limitations, to ensure maximal procedural safety and success. This is especially true for bifurcation lesion stenting, during which device integrity will often be eventually tested by undergoing specific procedural steps, such as proximal balloon optimization, kissing-balloon inflations, or even intentional stent crushing. In this review we address the design characteristics of contemporary DES, their bifurcation-specific experimental testing data, and reported clinical results, in an attempt to provide relevant information and help in device selection for bifurcation stenting procedures.

Scaling laws and the left main coronary artery bifurcation. A combination of geometric and simulation analyses

The geometry of coronary arteries is believed to play the role as an atherosclerotic risk factor on its own. The full characterization of the normal coronary network has been reported in the literature. Reports on the integration of geometry and functional data for normal coronary vessels started to proliferate more recently. In this work, we analyze and integrate the geometric data retrieved from angiography images of the left main coronary bifurcation in angiographically normal patients and hemodynamic data generated from blood flow models to analyze the role of allometric laws and the connection between flow distribution and wall shear stress loads on the left anterior descending and left circumflex arteries. This in-silico study contributes to the characterization of normal coronary anatomy and its impact on the hemodynamic shear stresses acting over the vessel wall, shedding light on the impact of geometry-based versus simulation-based hypotheses to define boundary conditions for numerical simulations. We discuss the role of the wall shear stress corresponding to scenarios adopted by the scientific community and the ones proposed in this study. For the simulation-based hypothesis, we propose an iterative strategy to define boundary conditions at the main left coronary bifurcation, such that wall shear stresses are matched between the left descending and left circumflex arteries. From this study, we conclude that a one-fits-all power law exponent of 7/3 results in an good trade-off between computational cost and wall shear stress balance between daughter vessels.

Influence of bifurcation angle in left coronary artery with stenosis: A CFD analysis.

The left coronary artery commonly known as LCA gets divided into two branches, such as the left circumflex (LCX) and left anterior descending (LAD) at a particular angle. This angle is varies from person to person. The present computational study contributes remarkable expertise about the influence of this angle variation on the hemodynamic parameters in the presence of 80% area stenosis at the LAD branch. This study aimed to compare the effect of the bifurcation angle on hemodynamic parameters in the left coronary artery with 80% stenosis. Computational models of left coronary bifurcation angles of 30°, 60°, 90°, 120° were developed to understand the flow behavior of left coronary artery branches. The 80% area stenosis (AS) is considered at the LAD branch immediate to bifurcation. Measurements of pressure, velocity and wall shear stress were carried out corresponding to various bifurcation angles. It was found that the drop-in pressure increases as the angle increases from narrow to wider. A slight elevation in the velocity at the stenosis was observed. In addition, the obtained results further reveal a recirculation region immediately after the plaque, which leads to more deposition of plaque in the flow obstructed area. It is known that the shear stress at the arterial wall across the stenosis increases as the angle of bifurcation increases from narrow to wider. The bifurcation of the left coronary artery and size of the stenosis have a notable impact on the pressure and wall shear stress. These two factors should be given due consideration by cardiologists to assess the complexity of stenosis in the LCA branches.

A computational study of branch-wise curvature in idealized coronary artery bifurcations

The curvature of coronary arteries can significantly influence their hemodynamics, particularly at coronary bifurcations. The present work aims to investigate the effect of individual branch curvatures on atherosclerotic susceptibility using idealized left coronary bifurcations with dimensions from literature, through computational fluid dynamics (CFD). The bend angle has been used as the metric for curvature, being varied from 0° to 60° for each branch to cover a majority of the population, while keeping the other two branches at 0°. Hemodynamic indicators time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT) have been studied in the analysis. The results indicate that the individual curvature of each branch of the coronary bifurcation has an impact on the hemodynamics of all three branches. The curvature of either of the branches most significantly impacts the LAD branch, with an increase in the low TAWSS (12% for LM and 20% for LAD branch curvature) and high RRT areas (13% for LAD and 15% for LCx branch curvature) being observed. It may hence be said to be most susceptible to the formation of atherosclerotic lesions. The OSI is observed to be impacted only in the curved branch. In general, an increase in curvature is associated with an increase in the TAWSS. The high RRT area decreases (12%) with LM branch curvature, is negligibly variant for LAD branch curvature and increases (9%) with LCx branch curvature.

Hemodynamic impacts of hematocrit level by two-way coupled FSI in the left coronary bifurcation.

Cardiovascular disease is now under the influence of several factors that encourage researchers to investigate the flow of these vessels. Oscillation influences the blood circulation in the volume of red blood cells (RBC) strongly. Therefore, in this study, its effects have been considered on hemodynamic parameters in the elastic wall and coronary bifurcation. In this study, a 3D geometry of non-Newtonian and pulsatile blood circulation is considered in the left coronary artery bifurcation. The Casson model with various hematocrits is analyzed in elastic and rigid walls. The wall shear stress (WSS) cannot show the stenosis artery alone, therefore, the oscillatory shear index (OSI) is represented as a hemodynamic parameter of WSS individually of time. The results are determined using two-way fluid-structure interaction (FSI) coupling method using an arbitrary Lagrangian-Eulerian method. The most prominent difference in velocity happened in the bifurcation and at hematocrit 30 with yield stress 6.59E-04 Pa. The backflow and vortex flow in the LCx branch grown with increasing shear rates. The likelihood of plaque generation at the ending of the LM branch is observed in hematocrits 10 and 20, while the WSS magnitude is normal in the hematocrit 60 with the greatest yield stress in the bifurcation. The shear stress among the rigid and elastic models is the highest at the ending of the LM branch. The wall shear stress magnitude among the models decreased at most of 24.49% by dividing the flow. Time-independent results for models showed that there is the highest value of OSI at the bifurcation, which then quickly dropped.

Accuracy of the PARIS score and PCI complexity to predict ischemic events in patients treated with very thin stents in unprotected left main or coronary bifurcations.

The PARIS risk score (PARIS-rs) and percutaneous coronary intervention complexity (PCI-c) predict clinical and procedural residual ischemic risk following PCI. Their accuracy in patients undergoing unprotected left main (ULM) or bifurcation PCI has not been assessed. The predictive performances of the PARIS-rs (categorized as low, intermediate, and high) and PCI-c (according to guideline-endorsed criteria) were evaluated in 3,002 patients undergoing ULM/bifurcation PCI with very thin strut stents. After 16 (12-22) months, increasing PARIS-rs (8.8% vs. 14.1% vs. 27.4%, p < .001) and PCI-c (15.2% vs. 11%, p = .025) were associated with higher rates of major adverse cardiac events ([MACE], a composite of death, myocardial infarction [MI], and target vessel revascularization), driven by MI/death for PARIS-rs and target lesion revascularization/stent thrombosis for PCI-c (area under the curves for MACE: PARIS-rs 0.60 vs. PCI-c 0.52, p-for-difference < .001). PCI-c accuracy for MACE was higher in low-clinical-risk patients; while PARIS-rs was more accurate in low-procedural-risk patients. ≥12-month dual antiplatelet therapy (DAPT) was associated with a lower MACE rate in high PARIS-rs patients, (adjusted-hazard ratio 0.42 [95% CI: 0.22-0.83], p = .012), with no benefit in low to intermediate PARIS-rs patients. No incremental benefit with longer DAPT was observed in complex PCI. In the setting of ULM/bifurcation PCI, the residual ischemic risk is better predicted by a clinical risk estimator than by PCI complexity, which rather appears to reflect stent/procedure-related events. Careful procedural risk estimation is warranted in patients at low clinical risk, where PCI complexity may substantially contribute to the overall residual ischemic risk.

Incidence of Adverse Events at 3 Months Versus at 12 Months After Dual Antiplatelet Therapy Cessation in Patients Treated With Thin Stents With Unprotected Left Main or Coronary Bifurcations

Incidence and predictors of adverse events after dual antiplatelet therapy (DAPT) cessation in patients treated with thin stents (<100 microns) in unprotected left main (ULM) or coronary bifurcation remain undefined. All consecutive patients presenting with a critical lesion of an ULM or involving a main coronary bifurcation who were treated with very thin strut stents were included. MACE (a composite end point of cardiovascular death, myocardial infarction [MI], target lesion revascularization [TLR], and stent thrombosis [ST]) was the primary endpoint, whereas target vessel revascularization (TVR) was the secondary endpoint, with particular attention to type and occurrence of ST and occurrence of ST, CV death, and MI during DAPT or after DAPT discontinuation. All analyses were performed according to length of DAPT dividing the patients in 3 groups: Short DAPT (3-months), intermediate DAPT (3 to 12 months), and long DAPT (12-months). A total of 117 patients were discharged with an indication for DAPT ≤3 months (median 1: 1 to 2.5), 200 for DAPT between 3 and 12 months (median 8: 7 to 10), and 1,958 with 12 months DAPT. After 12.8 months (8 to 20), MACE was significantly higher in the 3-month group compared with 3 to 12 and 12-month groups (9.4% vs 4.0% vs 7.2%, p ≤0.001), mainly driven by MI (4.4% vs 1.5% vs 3%, p ≤0.001) and overall ST (4.3% vs 1.5% vs 1.8%, p ≤0.001). Independent predictors of MACE were low GFR and a 2 stent strategy. Independent predictors of ST were DAPT duration <3 months and the use of a 2-stent strategy. In conclusion, even stents with very thin strut when implanted in real-life ULM or coronary bifurcation patients discharged with short DAPT have a relevant risk of ST, which remains high although not significant after DAPT cessation.

P972A subgroup analysis from the RAIN-CARDIOGROUP VII study: incidence of adverse events after DAPT cessation in patients treated with ultrathin stents in ULM or coronary bifurcations

Abstract Introduction Incidence and predictors of adverse events after dual antiplatelet therapy (DAPT) cessation in patients treated with ultrathin stents in unprotected left main (ULM) or coronary bifurcation remain undefined. Methods All consecutive patients presenting with a critical lesion of an ULM or a lesion involving a main coronary bifurcation and treated with very thin strut stents were included. MACE (a composite end point of cardiovascular death, myocardial infarction (MI), target lesion revascularization (TLR) and stent thrombosis (ST) was the primary endpoint, while target vessel revascularization (TVR) was the secondary endpoint. Moreover, type and occurrence of ST and occurrence of ST, CV death and MI during DAPT or after DAPT discontinuation were also evaluated. All analyses were performed according to length of DAPT dividing the patients in 3 groups: short DAPT (3-months), intermediate DAPT (3–12 months) and long DAPT (12-months). Results 117 patients were discharged with an indication for DAPT≤3 months (median 1:1–2.5), 200 for DAPT between 3 and 12 months (median 8:7–10) and 1958 with 12 months DAPT. After 12.8 months (8–20), MACE was significantly higher in the 3-month group compared to 3–12 and 12-month groups (9.4% vs. 4.0% vs. 7.2%, p≤0.001), mainly driven by MI (4.4% vs. 1.5% vs. 3%, p≤0.001) and overall ST (4.3% vs. 1.5% vs. 1.8%, p≤0.001). ST post DAPT cessation were comparable (1.7% vs. 0% vs. 0.7%, p=0.42) with a median time to ST post DAPT discontinuation of 1.67 months (0.48–4.7). At multivariate analysis, DAPT of 12-months compared to 3-months reduces the risk of overall ST (OR 0.103: 0.019–0.0563, 95% CI) while only a trend was noted for DAPT between 3 and 12 months (OR 0.61: 0.186–2.005, 95% CI). When analysed by stent strategy a 2-stent strategy predicted ST post DAPT cessation (OR 3.241: 1.048–10.026, 95% CI), which was reduced by use of FKB (OR 0.101:0.01–0.872, 95% CI). Conclusion Even stents with very thin strut when implanted in real-life ULM or coronary bifurcation patients discharged with short DAPT have a relevant risk of ST, which remains high although not significant after DAPT cessation. The correct identification before PCI of the more fragile patients who may receive a shorter DAPT regimen could help identify the safest PCI technique: provisional stenting and use of final kissing balloon (FKB) are the safest options.

Effect of left coronary bifurcation angle and left main coronary artery length on coronary artherosclerotic plaque burden

Effect of left coronary bifurcation angle and left main coronary artery length on coronary artherosclerotic plaque burden

Primary stenosis progression versus secondary stenosis formation in the left coronary bifurcation: A mechanical point of view

Biomechanical forces and hemodynamic factors influence the blood flow and the endothelial cells (ECs) morphology. These factors behave differently beyond the coronary artery stenosis. In the present study, unsteady blood flow in the left coronary artery (LCA) and its atherosclerotic bifurcating vessels, left anterior descending (LAD) and left circumflex (LCX) arteries, were numerically simulated to investigate the risk of plaque length development and secondary plaque formation in the post-stenotic areas. Using fluid–structure interaction (FSI) model, compliance of arterial wall and vessel curvature variations due to cardiac motion were considered. The arteries included plaques at the beginning of the bifurcation. Stenosis degree varied from 40% to 70% based on diameter reduction. Healthy coronary artery was also reconstructed to compare with the atherosclerotic arteries. Circumferential and longitudinal strains of ECs as well as wall shear stress (WSS) were computed in different locations downstream of the stenosis. It was concluded that the most critical regions experiencing low circumferential strain and low WSS were located proximal to the plaque throat, and the effects of these parameters intensified by stenosis degree. The results proposed that primary plaque length progression is more probable than secondary plaque formation distal to the stenosis when the stenosis degree increases.

A numerical study on hemodynamics in the left coronary bifurcation with normal and hypertension conditions.

In this study, a three-dimensional analysis of the non-Newtonian blood flow was carried out in the left coronary bifurcation. The Casson model and hyperelastic and rigid models were used as the constitutive equation for blood flow and vessel wall model, respectively. Physiological conditions were considered first normal and then compliant with hypertension disease with the aim of evaluating hemodynamic parameters and a better understanding of the onset and progression of atherosclerosis plaques in the coronary artery bifurcation. Two-way fluid-structure interaction method applying a fully implicit second-order backward Euler differencing scheme has been used which is performed in the commercial code ANSYS and ANSYS CFX (version 15.0). When artery deformations and blood pressure are associated, arbitrary Lagrangian-Eulerian formulation is employed to calculate the artery domain response using the temporal blood response. As a result of bifurcation, noticeable velocity reduction and backflow formation decrease shear stress and made it oscillatory at the starting point of the LCx branch which caused the shear stress to be less than 1 and 2Pa in the LCx and the LAD branches, respectively. Oscillatory shear index (OSI) as a hemodynamic parameter represents the increase in residence time and oscillatory wall shear stress. Because of using the ideal 3D geometry and realistic physiological conditions, the values obtained for shear stress are more accurate than the previous studies. Comparing the results of this study with previous clinical investigations shows that the regions with low wall shear stress less than 1.20Pa and with high OSI value more than 0.3 are in more potential risk to the atherosclerosis plaque development, especially in the posterior after the bifurcation.

An investigation of correlation between left coronary bifurcation angle and hemodynamic changes in coronary stenosis by coronary computed tomography angiography-derived computational fluid dynamics.

To investigate the correlation between left coronary bifurcation angle and coronary stenosis as assessed by coronary computed tomography angiography (CCTA)-generated computational fluid dynamics (CFD) analysis when compared to the CCTA analysis of coronary lumen stenosis and plaque lesion length with invasive coronary angiography (ICA) as the reference method. Thirty patients (22 males, mean age: 59±6.9 years) with calcified plaques at the left coronary artery were included in the study with all patients undergoing CCTA and ICA examinations. CFD simulation was performed to analyze hemodynamic changes to the left coronary artery models in terms of wall shear stress, wall pressure and flow velocity, with findings correlated to the coronary stenosis and degree of bifurcation angle. Calcified plaque length was measured in the left coronary artery with diagnostic value compared to that from coronary lumen and bifurcation angle assessments. Of 26 significant stenosis at left anterior descending (LAD) and 13 at left circumflex (LCx) on CCTA, only 14 and 5 of them were confirmed to be >50% stenosis at LAD and LCx respectively on ICA, resulting in sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 100%, 52%, 49% and 100%. The mean plaque length was measured 5.3±3.6 and 4.4±1.9 mm at LAD and LCx, respectively, with diagnostic sensitivity, specificity, PPV and NPV being 92.8%, 46.7%, 61.9% and 87.5% for extensively calcified plaques. The mean bifurcation angle was measured 83.9±13.6º and 83.8±13.3º on CCTA and ICA, respectively, with no significant difference (P=0.98). The corresponding sensitivity, specificity, PPV and NPV were 100%, 78.6%, 84.2% and 100% based on bifurcation angle measurement on CCTA, 100%, 73.3%, 78.9% and 100% based on bifurcation angle measurements on ICA, respectively. Wall shear stress was noted to increase in the LAD and LCx models with significant stenosis and wider angulation (>80º), but demonstrated little or no change in most of the coronary models with no significant stenosis and narrower angulation (<80º). This study further clarifies the relationship between left coronary bifurcation angle and significant stenosis, with angulation measurement serving as a more accurate approach than coronary lumen assessment or plaque lesion length for determining significant coronary stenosis. Left coronary bifurcation angle is suggested to be incorporated into coronary artery disease (CAD) assessment when diagnosing significant CAD.

Quantification of left coronary bifurcation angles and plaques by coronary computed tomography angiography for prediction of significant coronary stenosis: A preliminary study with dual-source CT.

PurposeTo evaluate the diagnostic performance of left coronary bifurcation angles and plaque characteristics for prediction of coronary stenosis by dual-source CT.Methods106 patients suspected of coronary artery disease undergoing both coronary computed tomography angiography (CCTA) and invasive coronary angiography (CAG) within three months were included. Left coronary bifurcation angles including the angles between the left anterior descending artery and left circumflex artery (LAD-LCx), left main coronary artery and left anterior descending artery (LM-LAD), left main coronary artery and left circumflex artery (LM-LCx) were measured on CT images. CCTA plaque parameters were calculated by plaque analysis software. Coronary stenosis ≥ 50% by CAG was defined as significant.Results106 patients with 318 left coronary bifurcation angles and 126 vessels were analyzed. The bifurcation angle of LAD-LCx was significantly larger in left coronary stenosis ≥ 50% than stenosis < 50%, and significantly wider in the non-calcified plaque group than calcified. Multivariable analyses showed the bifurcation angle of LAD-LCx was an independent predictor for significant left coronary stenosis (OR = 1.423, P = 0.002). In ROC curve analysis, LAD-LCx predicted significant left coronary stenosis with a sensitivity of 66.7%, specificity of 78.4%, positive predictive value of 85.2% and negative predictive value of 55.8%. The lipid plaque volume improved the diagnostic performance of CCTA diameter stenosis (AUC: 0.854 vs. 0.900, P = 0.045) in significant coronary stenosis.ConclusionsThe bifurcation angle of LAD-LCx could predict significant left coronary stenosis. Wider LAD-LCx is related to non-calcified lesions. Lipid plaque volume could improve the diagnostic performance of CCTA for coronary stenosis prediction.

Peripheral Arteries May Be Reliable Indicators of Coronary Vascular Disease.

Atherosclerosis is a stronger predictor for ischemic cardiovascular events than traditional risk factors such as race, age, sex, history, and metabolic profile. Previous research had primarily used ultrasound; however, we performed a study using histopathology to more accurately grade atherosclerosis development using the American Heart Association's grading scale. We cross-sectioned 13 different arteries from 48 cadavers and placed them into three separate groups based on anatomic location: central arteries, peripheral arteries, and carotid arteries. The central artery group included arteries that are non-palpable and commonly lead to ischemic diseases when occluded. The peripheral artery group included arteries that are accessible to palpation. The carotid artery group included branches of the carotid artery. We investigated whether a centrally located atherosclerotic vessel was associated with atherosclerosis of a specific peripheral artery. We hypothesized a correlation between carotid, peripheral and central arteries that may point to specific arteries that are more effective to analyze clinically when assessing cardiovascular risk. We observed a correlation between pathology in the left coronary artery and bifurcation of the carotid artery (r = 0.37 P ≤ 0.016), two arteries known to be implicated in ischemic stroke and ischemic heart disease. Importantly, our study demonstrates that the radial artery, a peripheral vessel, exhibited a positive correlation between both the pathologic left coronary (r = 0.33 P ≤ 0.041) and bifurcation of the carotid arteries (r = 0.34 P ≤ 0.025). Therefore, we propose investigating the radial artery as a clinically accessible location to monitor with ultrasound when assessing a patient's risk for ischemic cardiovascular disease. Anat Rec, 300:1230-1239, 2017. © 2017 Wiley Periodicals, Inc.

Diagnostic Value of Coronary CT Angiography With Use of Left Coronary Bifurcation Angle in Coronary Artery Disease

Background: Atherosclerosis generally occurs in the blood vessels with angulation or curvature, however, association between coronary bifurcation angle and coronary artery disease needs to be further clarified when compared to normal patients. Objectives: The aim of this study is to determine the relationship between left coronary bifurcation angle and development of coronary artery disease when compared to patients with normal coronary arteries. Methods: Fifty patients (40 men, mean age, 55.2 years) who underwent coronary computed tomography (CT) angiography for clinical diagnosis of coronary artery disease were included in the study. Of these patients, coronary plaques were present at one or more coronary arteries in 25 patients, while in the remaining 25 cases, no plaque was detected at the coronary arteries, thus serving as the control group. Left coronary bifurcation angle between left anterior descending and left circumflex was measured on 3D volume rendering images by two assessors with >80o as the cut-off value to determine significant stenosis. Results: The mean bifurcation angle was 72.9o±19.4o (range, 36o, 112o) among 50 patients. The mean bifurcation angle was significantly wider in patients with coronary plaques than that measured in patients with normal coronary artery (p 80o, while only 12% of the patients had a bifurcation angle >80o in the control group. Conclusion: This study further confirms the direct relationship between left coronary bifurcation angle and development of coronary artery disease with diseased coronary arteries associated with wider angulation.

Coronary fractional flow reserve measurements of a stenosed side branch: a computational study investigating the influence of the bifurcation angle.

BackgroundCoronary hemodynamics and physiology specific for bifurcation lesions was not well understood. To investigate the influence of the bifurcation angle on the intracoronary hemodynamics of side branch (SB) lesions computational fluid dynamics simulations were performed.MethodsA parametric model representing a left anterior descending—first diagonal coronary bifurcation lesion was created according to the literature. Diameters obeyed fractal branching laws. Proximal and distal main branch (DMB) stenoses were both set at 60 %. We varied the distal bifurcation angles (40°, 55°, and 70°), the flow splits to the DMB and SB (55 %:45 %, 65 %:35 %, and 75 %:25 %), and the SB stenoses (40, 60, and 80 %), resulting in 27 simulations. Fractional flow reserve, defined as the ratio between the mean distal stenosis and mean aortic pressure during maximal hyperemia, was calculated for the DMB and SB (FFRSB) for all simulations.ResultsThe largest differences in FFRSB comparing the largest and smallest bifurcation angles were 0.02 (in cases with 40 % SB stenosis, irrespective of the assumed flow split) and 0.05 (in cases with 60 % SB stenosis, flow split 55 %:45 %). When the SB stenosis was 80 %, the difference in FFRSB between the largest and smallest bifurcation angle was 0.33 (flow split 55 %:45 %). By describing the ΔPSB−QSB relationship using a quadratic curve for cases with 80 % SB stenosis, we found that the curve was steeper (i.e. higher flow resistance) when bifurcation angle increases (ΔP = 0.451*Q + 0.010*Q2 and ΔP = 0.687*Q + 0.017*Q2 for 40° and 70° bifurcation angle, respectively). Our analyses revealed complex hemodynamics in all cases with evident counter-rotating helical flow structures. Larger bifurcation angles resulted in more pronounced helical flow structures (i.e. higher helicity intensity), when 60 or 80 % SB stenoses were present. A good correlation (R2 = 0.80) between the SB pressure drop and helicity intensity was also found.ConclusionsOur analyses showed that, in bifurcation lesions with 60 % MB stenosis and 80 % SB stenosis, SB pressure drop is higher for larger bifurcation angles suggesting higher flow resistance (i.e. curves describing the ΔPSB−QSB relationship being steeper). When the SB stenosis is mild (40 %) or moderate (60 %), SB resistance is minimally influenced by the bifurcation angle, with differences not being clinically meaningful. Our findings also highlighted the complex interplay between anatomy, pressure drops, and blood flow helicity in bifurcations.

Influence of Variable Bifurcation Angulation and Outflow Boundary Conditions in 3D Finite Element Modelling of Left Coronary Artery on Coronary Diagnostic Parameter

Theoretical impact of left coronary bifurcation angulation (BA) variations and percentage of flow distribution variations (FDV) in coronary artery branches (CAB) on anatomic assessment of bifurcated lesions, is investigated by considering fractional flow reserve (FFR) as a standard diagnostic parameter. According to Medina classification, computational models of coronary bifurcation lesions types of (1, 0, 0), (0, 1, 0) and (0, 0, 1) were developed. The models included BA of 30°, 45°, 60° 75°, 90° and 120°. Computational fluid dynamics analysis was performed under hyperaemic flow condition and FFR was evaluated with percentage of FDV in CAB. For any fixed percentage of flow in the CAB and change in BA, FFR was significantly affected in the lesion type (1, 0, 0) whereas no significance was found in the lesion types (0, 1, 0) and (0, 0, 1). Percentage of FDV in CAB for any fixed BA significantly altered FFR in all the lesion types. Overall, 5%, 41% and 73% variations in FFR were found in (1, 0, 0), (0, 1, 0) and (0, 0, 1) respectively. The variation of BA could not be neglected in in vitro anatomical assessment for lesion type (1, 0, 0) but not in case of (0, 1, 0) and (0, 0, 1). Nevertheless, percentage of FDV in CAB is significantly altered FFR in the left coronary bifurcation lesions, which lead to underestimation of stenosis severity and postponement of coronary interventional procedure.

Computational fluid dynamic analysis of calcified coronary plaques: correlation between hemodynamic changes and cardiac image analysis based on left coronary bifurcation angle and lumen assessments

The purpose of this study was to determine the relationship between left coronary bifurcation angle and significant coronary stenosis with use of coronary CT angiography (CCTA)-generated computational fluid dynamics (CFD) analysis when compared to the CCTA analysis of coronary lumen stenosis with invasive coronary angiography (ICA) as the reference method. Eleven patients with calcified plaques at the left coronary artery tree who underwent CCTA and ICA examinations were included in the study. CFD simulation of left coronary models was performed to analyse hemodynamic changes including wall shear stress, wall pressure and flow velocity. The mean bifurcation angle was measured 83.3 ± 17.1º and 83.3 ± 17.0º on CCTA and ICA, respectively, with no significant difference (p=0.99). Of 15 significant stenosis at left anterior descending (LAD) and left circumflex (LCx) on CCTA, only 3 of them were confirmed to be >50% stenosis on ICA. Wall shear stress was noted to increase in the LAD and LCx models with significant stenosis and wider angulation (>80º), but remained no change in most of the other coronary models with no significant stenosis and narrower angulation. Wall pressured was decreased at the significant stenotic lesions, while flow velocity was increased with flow turbulence at the post-stenotic sites. This study further clarifies the direct correlation between left coronary bifurcation angle and significant stenosis, with angulation measurement being more accurate than lumen assessment for diagnosing significant stenosis.

Coronary CT angiography evaluation of calcified coronary plaques by measurement of left coronary bifurcation angle

Coronary CT angiography evaluation of calcified coronary plaques by measurement of left coronary bifurcation angle

Haemodynamic analysis of the effect of different types of plaques in the left coronary artery

PurposeCoronary plaque has been shown to directly affect the blood parameters, however, haemodynamic variations based on the plaque configuration has not been studied. In this study we investigate the haemodynamic effects of various types of plaques in the left coronary bifurcation. MethodsEight types of plaque configurations were simulated and located in various positions in the left main stem, the left anterior descending and left circumflex to produce a >50% narrowing of the coronary lumen. We analyse and characterise haemodynamic effects caused by each type of plaque. Computational fluid dynamics was performed to simulate realistic physiological conditions that reveal the in vivo cardiac haemodynamics. Velocity, wall shear stress (WSS) and pressure gradient (PSG) in the left coronary artery were calculated and compared in all plaque configurations during cardiac cycles. ResultsOur results showed that the highest velocity and PSG were found in the type of plaque configuration which involved all of the three left coronary branches. Plaques located in the left circumflex branch resulted in highly significant changes of the velocity, WSS and PSG (p<0.001) when compared to the other types of plaque configurations. ConclusionOur analysis provides an insight into the distribution of plaque at the left bifurcation, and corresponding haemodynamic effects, thus, improving our understanding of atherosclerosis.