Plaque Progression in a Human Coronary Artery is Associated With Low Wall Shear Stress and Extended Particle Residence Time

Author(s):  
Jin Suo ◽  
Michael McDaniel ◽  
Parham Eshtehardi ◽  
Saurabh Dhawan ◽  
Ravi Prasad Avati Nanjundappa ◽  
...  

Intravascular ultrasound (IVUS) evaluation was performed in the coronary arteries of a 45-year-old patient with stable angina during vigorous physical activity. Concurrent angiography demonstrated a mild plaque in the proximal left anterior descending artery (LAD), with obvious lumen dilatation immediately distal to the plaque. Blood velocity was measured by a catheter Doppler transducer at proximal and distal segments of the left coronary artery, and the left main artery (LM) and LAD were reconstructed using a 3D-IVUS reconstruction technique based on biplanar angiography and IVUS images, enabling simulation of the flow field in the artery employing computational fluid dynamics (CFD). Wall shear stress (WSS) and particle path lines were determined from the CFD studies. The patient returned for a follow up evaluation after 6 months, and plaque progression during this period was evaluated from the IVUS data. Results showed that low WSS, less than 5 dynes/cm2, which occurs in the region immediately distal to the plaque, correlates with localized progression of the lesion over the 6 month interval. The path line tracking computations showed that particles near the vessel surface where plaque progression was observed resided near the artery wall longer than one complete cardiac cycle, whereas in other areas particles were flushed through the region of interest rapidly. These observations in a specific individual are consistent with the hypothesis that plaque progression is related to low WSS and relatively long residence time of atherogenic blood-borne substances.

Author(s):  
Claudio Chiastra ◽  
Valentina Mazzi ◽  
Maurizio Lodi Rizzini ◽  
Karol Calò ◽  
Anna Corti ◽  
...  

Abstract Despite the important advancements in the stent technology for the treatment of diseased coronary arteries, major complications still affect the post-operative long-term outcome. The stent-induced flow disturbances, and especially the altered wall shear stress (WSS) profile at the strut level, play an important role in the pathophysiological mechanisms leading to stent thrombosis (ST) and in-stent restenosis (ISR). In this context, the analysis of the WSS topological skeleton is gaining more and more interest by extending the current understanding of the association between local hemodynamics and vascular diseases. The present study aims to analyze the impact that a deployed coronary stent has on the WSS topological skeleton. Computational fluid dynamics simulations were performed in three stented human coronary artery geometries reconstructed from clinical images. The selected cases presented stents with different designs (i.e., two contemporary drug eluting stents and one bioresorbable scaffold) and included regions with stent malapposition or overlapping. A recently proposed Eulerian-based approach was applied to analyze the WSS topological skeleton features. The results highlighted that the presence of single or multiple stents within a coronary artery markedly impacts the WSS topological skeleton. In particular, repetitive patterns of WSS divergence were observed at the luminal surface, highlighting a WSS contraction action proximal to the struts and a WSS expansion action distal to the struts. This WSS action pattern was independent from the stent design. In conclusions, these findings could contribute to a deeper understanding of the hemodynamic-driven processes underlying ST and ISR.


Author(s):  
Lucas H. Timmins ◽  
David S. Molony ◽  
Parham Eshtehardi ◽  
Michael C. McDaniel ◽  
John N. Oshinski ◽  
...  

Natural history data on clinical coronary artery disease (CAD) indicates that there is a critical need to prospectively identify rapidly progressing and vulnerable coronary lesions that may cause potentially fatal acute coronary events [1]. Recent prospective clinical investigations have evaluated the value of wall shear stress (WSS) as a prognostic marker for identifying rapidly progressing coronary lesions [2,3]. Data indicate that low WSS is associated with significant plaque progression, while regions of high WSS are associated with plaque regression and phenotypic transformation towards a more vulnerable lesion. While these studies provided unprecedented data on the role of hemodynamic-induced mechanical forces in lesion dynamics, they were limited by a lack of focal understanding of the association between WSS and plaque progression. Specifically, despite the understanding that WSS and plaque progression are heterogeneous around the artery’s circumference, in each image slice WSS values were spatially averaged around the circumference and correlated with average values for changes in virtual histology-intravascular ultrasound (VH-IVUS) defined plaque constituent areas.


2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E M J Hartman ◽  
A M Kok ◽  
A Hoogendoorn ◽  
F J H Gijsen ◽  
A F W Steen ◽  
...  

Abstract Introduction Local wall shear stress (WSS) metrics, high local lipid levels (as detected by near-infrared spectroscopy (NIRS)), as well as systemic lipid levels, have been individually associated with atherosclerotic disease progression. However, a possible synergistic effect remains to be elucidated. This study is the first study to combine WSS metrics with NIRS-detected local lipid content to investigate a potential synergistic effect on plaque progression in human coronary arteries. Methods The IMPACT study is a prospective, single centre study investigating the relation between atherosclerotic plaque progression and WSS in human coronary arteries. Patients with ACS treated with PCI were included. At baseline and after 1-year follow-up, patients underwent near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) imaging and intravascular doppler flow measurements of at least one non-culprit coronary artery. After one month, a CT angiography was made. CT derived centreline combined with IVUS lumen contours resulted in a 3D reconstruction of the vessel. The following WSS metrics were computed using computational fluid dynamics applying the vessel specific invasive flow measurements: time-average wall shear stress (TAWSS), relative residence time (RRT), cross-flow index, oscillatory shear index and transverse wall shear stress. Low TAWSS is known as pro atherogenic, in contrast to all the other shear stress metrics, at which a high magnitude is pro-atherogenic. The arteries were divided into 1.5mm/45° sectors. Based on NIRS-IVUS, wall thickness change over time was determined and NIRS positive sectors detected. Furthermore, per vessel the shear stress was divided into tertiles (low, intermediate, high). To investigate the synergistic effect of local lipids on shear stress related plaque growth, wall thickness change over time was related to the different shear stress metrics comparing the NIRS-positive with the NIRS-negative sectors. Results 15 non-culprit coronary arteries from the first 14 patients were analyzed (age 62±10 years old and 92.9% male). A total of 2219 sectors were studied (5.2%, N=130, NIRS-positive) for wall thickness changes. After studying all five shear stress metrics, we found for TAWSS and RRT that presence of lipids, as detected by NIRS, amplified the effect of shear stress on plaque progression (see figure). Sectors presenting with lipid-rich plaque, compared to NIRS-negative sectors, showed more progression when they were exposed to low TAWSS (p=0.07) or high RRT (p=0.012) and more regression in sectors exposed to high TAWSS (p=0.10) or low RRT (p=0.06). Delta wall thickness vs shear stress Conclusion We presented the first preliminary results of the IMPACT study, showing the synergistic effect of lipid rich plaque and shear stress on plaque progression. Therefore, intravascular lipid-rich plaque (NIRS) assessment has added value to shear stress profiling for the prediction of plaque growth, leading to improved risk stratification. Acknowledgement/Funding ERC starting grant 310457


2018 ◽  
Vol 5 (3) ◽  
pp. 171447 ◽  
Author(s):  
R. Xing ◽  
A. M. Moerman ◽  
Y. Ridwan ◽  
M. J. Daemen ◽  
A. F. W. van der Steen ◽  
...  

Wall shear stress (WSS) is involved in atherosclerotic plaque initiation, yet its role in plaque progression remains unclear. We aimed to study (i) the temporal and spatial changes in WSS over a growing plaque and (ii) the correlation between WSS and plaque composition, using animal-specific data in an atherosclerotic mouse model. Tapered casts were placed around the right common carotid arteries (RCCA) of ApoE −/− mice. At 5, 7 and 9 weeks after cast placement, RCCA geometry was reconstructed using contrast-enhanced micro-CT. Lumen narrowing was observed in all mice, indicating the progression of a lumen intruding plaque. Next, we determined the flow rate in the RCCA of each mouse using Doppler Ultrasound and computed WSS at all time points. Over time, as the plaque developed and further intruded into the lumen, absolute WSS significantly decreased. Finally at week 9, plaque composition was histologically characterized. The proximal part of the plaque was small and eccentric, exposed to relatively lower WSS. Close to the cast a larger and concentric plaque was present, exposed to relatively higher WSS. Lower WSS was significantly correlated to the accumulation of macrophages in the eccentric plaque. When pooling data of all animals, correlation between WSS and plaque composition was weak and no longer statistically significant. In conclusion, our data showed that in our mouse model absolute WSS strikingly decreased during disease progression, which was significantly correlated to plaque area and macrophage content. Besides, our study demonstrates the necessity to analyse individual animals and plaques when studying correlations between WSS and plaque composition.


2015 ◽  
Vol 14 (Suppl 1) ◽  
pp. S2 ◽  
Author(s):  
David S Molony ◽  
Lucas H Timmins ◽  
Olivia Y Hung ◽  
Emad Rasoul-Arzrumly ◽  
Habib Samady ◽  
...  

2004 ◽  
Vol 24 (12) ◽  
pp. 2408-2413 ◽  
Author(s):  
Anil K. Joshi ◽  
Richard L. Leask ◽  
Jerry G. Myers ◽  
Matadial Ojha ◽  
Jagdish Butany ◽  
...  

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mongkol Kaewbumrung ◽  
Somsak Orankitjaroen ◽  
Pichit Boonkrong ◽  
Buraskorn Nuntadilok ◽  
Benchawan Wiwatanapataphee

A mathematical model of dispersed bioparticle-blood flow through the stenosed coronary artery under the pulsatile boundary conditions is proposed. Blood is assumed to be an incompressible non-Newtonian fluid and its flow is considered as turbulence described by the Reynolds-averaged Navier-Stokes equations. Bioparticles are assumed to be spherical shape with the same density as blood, and their translation and rotational motions are governed by Newtonian equations. Impact of particle movement on the blood velocity, the pressure distribution, and the wall shear stress distribution in three different severity degrees of stenosis including 25%, 50%, and 75% are investigated through the numerical simulation using ANSYS 18.2. Increasing degree of stenosis severity results in higher values of the pressure drop and wall shear stresses. The higher level of bioparticle motion directly varies with the pressure drop and wall shear stress. The area of coronary artery with higher density of bioparticles also presents the higher wall shear stress.


Author(s):  
Pedro D. Pedroso ◽  
Andreas S. Anayiotos ◽  
Brad L. Hershey ◽  
Evangelos Eleftheriou ◽  
William L. Holman

Coronary artery disease (CAD) is the leading cause of death in the world today. According to the American Heart Association 529,659 people in 1999 died as a result of CAD [1]. Starting in the 1960’s, surgeons have used Coronary Artery Bypass Graft (CABG) techniques in order to reestablish blood flow to the heart. Today, the procedure remains the same, using autologous grafts, such as the mammary artery and the saphenous vein. An unresolved problem, is that a significant number of CABGs reocclude months to years postoperatively. In the case of Saphenous Vein Grafts (SVGs) typically 50% of these bypasses are totally occluded months to years after the procedure, the remaining half being more than 50% occluded [2]. The re-occlusion of CABGs is due to a process labeled intimal hyperplasia (IH). Investigators have shown that IH, believed by some to be a remodeling process, occurs at branch sites, regions of curvature, and anastomotic junctions [3,4]. At these sites there are low residence times, slow secondary structures, disturbed flow, and areas of recirculation, therefore the onset of IH is believed to be hemodynamically linked. Most recently, floor IH has been attributed to four variables: time averaged wall shear stress (WSS), oscillating shear index (OSI), spatial wall shear stress gradients (WSSG), and temporal WSSG [5]. Adverse values of these parameters, in the case of SVGs, are believed to be caused by impedance mismatch at the anastomosis site. Over time this characteristic causes a bulge at the sinus. Such a morphology additionally contributes to disturbed flows which tend to propagate down the CABG and are believed to play a major role in the development of IH and the eventual failure of the graft.


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