Basilar artery bifurcation anatomy as a determinant of recanalization and stroke outcome: Basilar artery bifurcation anatomy and stroke outcome

OBJECTIVES

Thrombectomy improves outcomes in patients with basilar artery (BA) occlusion. We hypothesized that the anatomic configuration of the BA bifurcation, classified as T- or Y-shaped, may impact the outcome as a T-shaped BA would involve more deep penetrating arteries of the midbrain and thalamus.

MATERIALS AND METHODS

In this 2-center retrospective cohort study, we included patients with stroke due to distal BA occlusion and performed blinded classification of their BA distal bifurcation as either T- or Y-shaped. The primary outcomes were favorable outcome at 90-days (modified Rankin Scale 0 - 2) and successful recanalization (TICI scores 2B or 3).

RESULTS

70 patients (mean age 66 years, 36% women) were included. 38 had T- and 32 had Y-shaped bifurcations. Baseline characteristics were similar for both groups, including demographics, onset to arterial puncture time, baseline NIHSS, THRIVE score, posterior circulation collateral score, and presence of tandem occlusion. Comparing the T- to the Y- shape, there was no difference in the likelihood of successful recanalization (RR: 1.02, CI: [0.86-1.21], p=1.00) nor 90-day favorable mRS (0-2) score (RR: 0.58, CI: [0.25-1.32]; p=0.18). Similarly, mortality at 30 and 90-days were not significantly affected by the type of bifurcation.

CONCLUSIONS

The configuration of the basilar artery does not significantly impact on recanalization success or stroke outcome in our study. Further studies are needed to confirm our observations.

Coronary computed tomography angiography study on the relationship between the Ramus Intermedius and Atherosclerosis in the bifurcation of the left main coronary artery

OBJECTIVE

This study aimed to explore the relationship between the ramus intermedius (RI) and atherosclerosis in the bifurcation of the left coronary artery (LCA).

METHODS

Screening patients who underwent CCTA from January to September 2021, 100 patients with RI (RI group) and 100 patients without RI (no-RI group) were randomly enrolled, Evaluation of RI distribution characteristics and left main coronary artery(LM),Left anterior descending branch(LAD),left circumflex branch(LCX) proximal segment plaque distribution, measurement of LAD-LCX bifurcation angle(∠LAD-LCX),Comparison of the three distribution characteristics with the incidence of plaques in the left main trunk bifurcation area (LM, LAD, LCX) between groups and within the RI group.

RESULTS

The difference in the incidence of plaques in the proximal LCX and the LM between the RI group and the no-RI group were not statistically significant (P > 0.05). The incidence of plaques in the proximal LAD in the RI group was significantly higher than that in the non-RI group (77% versus 53%, P < 0.05). However, there was no statistically significant difference between the two groups after PSM. A univariate logistic regression analysis revealed that an RI was a risk factor for plaque formation in the proximal LAD (P < 0.001), and a multivariate logistic regression analysis revealed that an RI was not an independent risk factor for plaque formation in the proximal LAD (P > 0.05). When compared within the RI group, the difference in the incidence of plaques in the proximal segment of LAD, the proximal segment of LCX, and the LM among the different distribution groups of RI was not statistically significant, respectively (P > 0.05).

CONCLUSION

RI is not an independent risk factor for atherosclerosis in the left coronary artery bifurcation zone, but it may indirectly increase the risk of atherosclerosis in the proximal segment of the LAD.

Middle cerebral arterial bifurcation aneurysms are associated with bifurcation angle and high tortuosity

PURPOSE

To investigate the association of middle cerebral artery (MCA) bifurcation aneurysms with bifurcation morphology.

MATERIALS AND METHODS

205 patients were enrolled, including 61 patients with MCA bifurcation aneurysms and 144 non-aneurysmal subjects. Aneurysmal cases were divided into types C (aneurysm neck on extension of the parent artery centerline) and D (deviating neck). The radius of the parent artery M1 (R_P) and bilateral branches (R_S and R_L, respectively), smaller (φ_S) and larger (φ_L) lateral angles, bifurcation angle, and arterial tortuosity from parent vessel to bilateral branches (T_S and T_L, respectively) were analyzed. Logistic regression and receiver operator characteristic (ROC) curve analysis were performed to identify risk factors and predictive values for MCA aneurysm presence and types.

RESULTS

In aneurysmal MCA bifurcations, bifurcating angle, T_S, T_L and R_L were significantly larger (P<0.01), while φ_S was significantly smaller (P<0.001) than those in controls. The bifurcation angle, T_S and LogitP were better morphological parameters for predicting MCA aneurysm presence with the AUC of 0.795, 0.932 and 0.951, respectively. Significant (P<0.05) differences were observed in the bifurcation angle, φ_L, R_P, R_L and T_L between types C and D aneurysmal bifurcations. T_L was an independent factor in discriminating types C from D aneurysms with an AUC of 0.802.

CONCLUSIONS

Bifurcation angle and arterial tortuosity from the parent artery to the branch forming a smaller angle with the parent artery have a higher value in distinguishing MCA aneurysmal from non-aneurysmal ones, and the tortuosity from the parent artery to the contralateral branch is the best indicator for distinguishing types C from D aneurysmal bifurcations.

Secondary flow in bifurcations - Important effects of curvature, bifurcation angle and stents

Coronary bifurcations have complex flow patterns including secondary flow zones and helical flow, which directly affect pathophysiological mechanisms such as the development of atherosclerosis. The objective of this study was to generate insights into the effects of curvature, bifurcation angle and the presence of stents on flow patterns and resulting haemodynamics in coronary left main bifurcations. The blood flow and associated metrics were modelled in both idealised and patient-specific bifurcations with varying curvature and bifurcation angles with and without stents, resulting in a total of 128 geometries considered. The results showed that larger curvature of bifurcating vessels has a significant influence on secondary flow, especially with distance to the bifurcation region, causing a skew, spin and asymmetry of Dean vortices, an increase in helical flow intensity with symmetry loss, and a decrease in adversely low time-average wall shear stress (TAWSS). Generally, asymmetric flow patterns coincided with adversely low TAWSS regions. In identical stented geometries, the presence of the stents induced local recirculation immediately adjacent to the stent struts, thus generating adversely low TAWSS in these areas, with some effect on the overall secondary flow. Overall, the effect of stents outweighed the effect of curvature and BA. This new knowledge contributes to a better understanding of the joint effects of curvature, bifurcation angle, and stents on flow patterns and haemodynamics in coronary bifurcations.

Image-guided simulation in comparison with laser speckle contrast imaging for full-field observation of blood flow in a microvasculature model

The in vitro reconstruction of the microvascular network model provides a reproducible platform for hemodynamic study with great biological relevance. In the present study, microvascular models with different parametric features were designed under the guidance of Murray's law and derived from representative natural vascular network topography in vivo. Computational fluid dynamics (CFD) was used to numerically simulate blood velocity distributions inside of the designed microvasculature models. Full-field blood flow in the vascular network was visualized in vivo using a laser speckle contrast imaging (LSCI) system, from which the measured relative velocity was compared with CFD computed flow distribution. The results have shown that, in comparison with the simplified flow patterns obtained from idealized geometries, the irregular vascular topography is expected to lead to nonuniform and poor regional blood velocity distribution. The velocity distribution acquired by in vivo LSCI experiment is in good agreement with that of numerical simulation, indicating the technical feasibility of using biomimetic microchannels as a reasonable approximation of the microcirculatory flow conditions. This study provides a new paradigm that can be well suited to the study of microvascular blood flow properties and can further expand to mimic other in-vivo scenarios for accurately recapitulating the physical and hemodynamic environment of the microcirculation.

Effect of Coronary Artery Bifurcation Angle on Atherosclerotic Lesion Localization Distance to the Bifurcation Site

Objectives

Although percutaneous coronary interventions become a common treatment modality for coronary artery diseases, lesion localization make these procedures more complex. As the lesion localizes near to the bifurcation site, more complex PCI procedures, overqualified equipments are needed and complication risk increases. Previous studies have demonstrated the strong correlation between wide angulation and significant coronary stenosis. However, a paucity of data exists about the association between bifurcation angle and lesion localization distance. In this study we analysed the effect of coronary bifurcation angle and left main coronary artery length on the atherosclerotic lesion localization.

Methods

Patients, who underwent coronary angiography between 01.01.2017- 31.12.2019 were scanned. Patients having atherosclerotic lesions causing more than 50% luminal narrowing and Medina classification score (0,0,0) were evaluated. After exclusion, 467 patients were included. 5 bifurcation subgroups (LAD-CX, LAD-Dx, CX-OM, RCA-RV, RPD-RPL) were formed. Distance of lesion to the bifurcation site, bifurcation angle and left main coronary artery length were analysed by 2 experienced cardiologists with invasive quantitaive coronary angiography (QCA) by using “extreme angio and cardiac pacs” software system.

Results

There was a strong inverse correlation between bifurcation angle and lesion localization distance to the bifurcation site (r = −0.706; p < 0.0001). There was a nonsignificant negative correlation between Left-main coronary artery length and lesion localization. Regression analysis revealed that bifurcation angle is an independent risk factor for predicting the localization of an atheroslerotic lesion in 5 mm length from the point of bifurcation site (β = −0.074, p < 0.0001). A cut-off value of 80.5° coronary bifurcation angle was found to have 84.1% sensitivity and 81.3% specificity in prediction of atherosclerotic lesion localization in 5 mm length from the point of bifurcation site.

Conclusion

In this study we showed that as the bifurcation angle increases, atherosclerotic lesions tend to approach to the bifurcation site. Since invertentions encompassing bifurcation sites are more complex, lesions with increased angulation may need extra care as they are more likely to present with further complications. Furthermore, bifurcation angle is an independent risk factor for lesion localization.

Quantitative CT-based structural alterations of segmental airways in cement dust-exposed subjects

Background

Dust exposure has been reported as a risk factor of pulmonary disease, leading to alterations of segmental airways and parenchymal lungs. This study aims to investigate alterations of quantitative computed tomography (QCT)-based airway structural and functional metrics due to cement-dust exposure.

Methods

To reduce confounding factors, subjects with normal spirometry without fibrosis, asthma and pneumonia histories were only selected, and a propensity score matching was applied to match age, sex, height, smoking status, and pack-years. Thus, from a larger data set (N = 609), only 41 cement dust-exposed subjects were compared with 164 non-cement dust-exposed subjects. QCT imaging metrics of airway hydraulic diameter (D_h), wall thickness (WT), and bifurcation angle (θ) were extracted at total lung capacity (TLC) and functional residual capacity (FRC), along with their deformation ratios between TLC and FRC.

Results

In TLC scan, dust-exposed subjects showed a decrease of D_h (airway narrowing) especially at lower-lobes (p < 0.05), an increase of WT (wall thickening) at all segmental airways (p < 0.05), and an alteration of θ at most of the central airways (p < 0.001) compared with non-dust-exposed subjects. Furthermore, dust-exposed subjects had smaller deformation ratios of WT at the segmental airways (p < 0.05) and θ at the right main bronchi and left main bronchi (p < 0.01), indicating airway stiffness.

Conclusions

Dust-exposed subjects with normal spirometry demonstrated airway narrowing at lower-lobes, wall thickening at all segmental airways, a different bifurcation angle at central airways, and a loss of airway wall elasticity at lower-lobes. The airway structural alterations may indicate different airway pathophysiology due to cement dusts.

Enlarged Anterior Cerebral Artery Bifurcation Angles May Induce Abnormally Enhanced Hemodynamic Stresses to Initiate Aneurysms

OBJECTIVE

To investigate the relationship of anterior cerebral artery (ACA) bifurcation angles with hemodynamic stresses for aneurysm initiation.

METHODS

Forty patients with or without anterior communicating artery aneurysms were enrolled, and 3 patients with ACA bifurcation angles of 169.0°, 136.9°, and 73.2°, respectively, were entered into computational fluid dynamics analysis for hemodynamic stresses.

RESULTS

Larger bifurcation angles had a larger direct flow impinging zone and larger peak pressure area. In the direct flow impinging center, the total pressure was the highest, whereas the other stresses were the lowest. As blood flowed distally, the total pressure decreased rapidly, whereas all other parameters increased quickly to their peaks. The hemodynamic peak distance was decreased as the bifurcation angle became narrower. The total pressure summit and the peak hemodynamic stresses all decreased with the decrease of bifurcation angles. The distance between the hemodynamic peaks was the smallest at 73.2° compared with larger angles. A significant (P < 0.01) positive linear correlation existed in the ACA bifurcation angle with the distance between hemodynamic stress peaks or in the ACA branch diameter with the distance from the direct impinging center to the ipsilateral hemodynamic stress peak. The hemodynamic stresses on the aneurysm dome were significantly (P < 0.001) smaller than at the aneurysm initiation site.

CONCLUSIONS

Larger bifurcation angles may lead to abnormally enhanced hemodynamic stresses, enlarged zones of direct flow impingement, and increased distance between hemodynamic stress peaks to damage the vascular wall for aneurysm initiation on the bifurcation apex wall.

N-terminal and central domains of APC function to regulate branch number, length and angle in developing optic axonal arbors in vivo

During formation of neuronal circuits, axons navigate long distances to reach their target locations in the brain. When axons arrive at their target tissues, in many cases, they extend collateral branches and/or terminal arbors that serve to increase the number of synaptic connections they make with target neurons. Here, we investigated how Adenomatous Polyposis Coli (APC) regulates terminal arborization of optic axons in living Xenopus laevis tadpoles. The N-terminal and central domains of APC that regulate the microtubule cytoskeleton and stability of β-catenin in the Wnt pathway, were co-expressed with GFP in individual optic axons, and their terminal arbors were then imaged in tectal midbrains of intact tadpoles. Our data show that the APCNTERM and APCβ-cat domains both decreased the mean number, and increased the mean length, of branches in optic axonal arbors relative to control arbors in vivo. Additional analysis demonstrated that expression of the APCNTERM domain increased the average bifurcation angle of branching in optic axonal arbors. However, the APCβ-cat domain did not significantly affect the mean branch angle of arbors in tecta of living tadpoles. These data suggest that APC N-terminal and central domains both modulate number and mean length of branches optic axonal arbors in a compensatory manner, but also define a specific function for the N-terminal domain of APC in regulating branch angle in optic axonal arbors in vivo. Our findings establish novel mechanisms for the multifunctional protein APC in shaping terminal arbors in the visual circuit of the developing vertebrate brain.

Effect of low-density lipoprotein cholesterol on the geometry of coronary bifurcation lesions and clinical outcomes of coronary interventions in the J-REVERSE registry

We investigated the effect of low-density lipoprotein cholesterol (LDL-C) on the geometry of coronary bifurcation lesions. A total of 300 non-left main bifurcation lesions in 298 patients from J-REVERSE registry were classified according to statin treatment status at admission (NT, non-treated; ST, statin-treated) and were further subdivided based on LDL-C levels with a cutoff of 100 mg/dL (NT-high, n = 76 lesions; NT-low, n = 46; ST-high, n = 99 and ST-low, n = 79). In addition, a group with strict control of LDL-C (< 70 mg/dL) was defined (ST-SC; n = 19). The NT-high group had higher angled bifurcations compared to that in the NT-low group (59.1° ± 21.5° vs. 50.3° ± 18.6°, p = 0.02). In the multivariate analysis, NT-high group was an independent factor contributing on generation of higher angled (> 80°) lesion (odds ratio 3.77, 95% CI 1.05-13.5, p = 0.04). The NT-low group had more men (95.6 vs. 81.6%, p = 0.03), and greater plaque volume in the distal main vessel (7.1 ± 3.2 mm³/mm vs. 5.7 ± 2.7 mm³/mm, p = 0.02), compared to those in the NT-high group. LDL-C was more likely to remain high after statin treatment in younger patients (65.3 ± 3.6 years vs. 68.6 ± 8.4 years, p = 0.02) and current smokers (36.7 vs. 16.9%, p = 0.004). The ST-SC group had limited luminal volume expansion compared to that in the ST-high group (proximal: 6.7 ± 1.4 mm³/mm vs. 7.7 ± 2.3 mm³/mm, p = 0.04; distal: 5.3 ± 1.5 mm³/mm vs. 6.5 ± 1.9 mm³/mm, p = 0.04), regardless of similar plaque volumes. Elevated LDL-C is likely to promote the generation of higher angled bifurcation lesions and multiple risk factors lead to a more progressed bifurcation lesion even in patients with lower LDL-C levels.

Salt-bridge networks within globular and disordered proteins: characterizing trends for designable interactions

There has been considerable debate about the contribution of salt bridges to the stabilization of protein folds, in spite of their participation in crucial protein functions. Salt bridges appear to contribute to the activity-stability trade-off within proteins by bringing high-entropy charged amino acids into close contacts during the course of their functions. The current study analyzes the modes of association of salt bridges (in terms of networks) within globular proteins and at protein-protein interfaces. While the most common and trivial type of salt bridge is the isolated salt bridge, bifurcated salt bridge appears to be a distinct salt-bridge motif having a special topology and geometry. Bifurcated salt bridges are found ubiquitously in proteins and interprotein complexes. Interesting and attractive examples presenting different modes of interaction are highlighted. Bifurcated salt bridges appear to function as molecular clips that are used to stitch together large surface contours at interacting protein interfaces. The present work also emphasizes the key role of salt-bridge-mediated interactions in the partial folding of proteins containing long stretches of disordered regions. Salt-bridge-mediated interactions seem to be pivotal to the promotion of "disorder-to-order" transitions in small disordered protein fragments and their stabilization upon binding. The results obtained in this work should help to guide efforts to elucidate the modus operandi of these partially disordered proteins, and to conceptualize how these proteins manage to maintain the required amount of disorder even in their bound forms. This work could also potentially facilitate explorations of geometrically specific designable salt bridges through the characterization of composite salt-bridge networks. Graphical abstract ᅟ.

Impact of bifurcation angle and other anatomical characteristics on blood flow - A computational study of non-stented and stented coronary arteries

The hemodynamic influence of vessel shape such as bifurcation angle is not fully understood with clinical and quantitative observations being equivocal. The aim of this study is to use computational modeling to study the hemodynamic effect of shape characteristics, in particular bifurcation angle (BA), for non-stented and stented coronary arteries. Nine bifurcations with angles of 40°, 60° and 80°, representative of ±1 SD of 101 asymptomatic computed tomography angiogram cases (average age 54±8 years; 57 females), were generated for (1) a non-stented idealized, (2) stented idealized, and (3) non-stented patient-specific geometry. Only the bifurcation angle was changed while the geometries were constant to eliminate flow effects induced by other vessel shape characteristics. The commercially available Biomatrix stent was used as a template and virtually inserted into each branch, simulating the T-stenting technique. Three patient-specific geometries with additional shape variation and ±2 SD BA variation (33°, 42° and 117°) were also computed. Computational fluid dynamics (CFD) analysis was performed for all 12 geometries to simulate physiological conditions, enabling the quantification of the hemodynamic stress distributions, including a threshold analysis of adversely low and high wall shear stress (WSS), low time-averaged WSS (TAWSS), high spatial WSS gradient (WSSG) and high Oscillatory Shear Index (OSI) area. The bifurcation angle had a minor impact on the areas of adverse hemodynamics in the idealized non-stented geometries, which fully disappeared once stented and was not apparent for patient geometries. High WSS regions were located close to the carina around peak-flow, and WSSG increased significantly after stenting for the idealized bifurcations. Additional shape variations affected the hemodynamic profiles, suggesting that BA alone has little effect on a patient׳s hemodynamic profile. Incoming flow angle, diameter and tortuosity appear to have stronger effects. This suggests that other bifurcation shape characteristics and stent placement/strategy may be more important than bifurcation angle in atherosclerotic disease development, progression, and stent outcome.

Coronary CT angiography in calcified coronary plaques: Comparison of diagnostic accuracy between bifurcation angle measurement and coronary lumen assessment for diagnosing significant coronary stenosis

BACKGROUND

To investigate the diagnostic value of coronary CT angiography (CCTA) by bifurcation angle measurement in the assessment of calcified plaques compared to conventional coronary lumen analysis.

METHODS

Fifty-three patients with calcified plaques identified on CCTA in the left coronary artery were included in the study. Minimal lumen diameter (MLD) and bifurcation angle between the left anterior descending (LAD) and left circumflex (LCx) arteries were measured and compared between CCTA and invasive coronary angiography (ICA), while the areas under the curves (AUCs) by receiver-operating characteristic curve analysis (ROC) were compared between CCTA and ICA with regard to the diagnostic value of using bifurcation angle as a criterion.

RESULTS

On a per-vessel assessment, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and 95% confidence interval (CI) with the use of bifurcation angle for determining coronary stenosis were 100% (86%, 100%), 79% (59%, 92%), 81% (62%, 92%), and 100% (85%, 100%) for CCTA, and 100% (86%, 100%), 82% (63%, 94%), 83% (65%, 94%), and 100% (85%, 100%) for ICA, respectively. While the sensitivity and NPV remained unchanged, the specificity and PPV of CCTA by MLD were 33% (21%, 47%) and 43% (31%, 56%). The AUCs by ROC curve analysis for CCTA and ICA bifurcation angle measurements demonstrated no significant difference (p>0.05, 0.79 vs 0.86, and 0.70 vs 0.68 at the LAD and LCx assessment, respectively).

CONCLUSION

Coronary CT angiography by bifurcation angle measurement shows significant improvement in the diagnosis of calcified plaques with diagnostic value comparable to invasive coronary angiography.