Limits...
Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations.

Beier S, Ormiston J, Webster M, Cater J, Norris S, Medrano-Gracia P, Young A, Cowan B - Ann Biomed Eng (2015)

Bottom Line: Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG.For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts.In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. s.beier@auckland.ac.nz.

ABSTRACT
Stent induced hemodynamic changes in the coronary arteries are associated with higher risk of adverse clinical outcome. The purpose of this study was to evaluate the impact of stent design on wall shear stress (WSS), time average WSS, and WSS gradient (WSSG), in idealized stent geometries using computational fluid dynamics. Strut spacing, thickness, luminal protrusion, and malapposition were systematically investigated and a comparison made between two commercially available stents (Omega and Biomatrix). Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG. Local hemodynamics worsened with luminal protrusion of the stent and with stent malapposition, adverse high WSS and WSSG were identified around peak flow and throughout the cardiac cycle respectively. For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts. In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

No MeSH data available.


Related in: MedlinePlus

Left main coronary blood flow over time prescribed as the inlet boundary condition (adapted from Nichols et al.33). Red circles indicate timepoints selected for transient analysis throughout the manuscript taken from the fourth simulated cardiac cycle.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4764643&req=5

Fig1: Left main coronary blood flow over time prescribed as the inlet boundary condition (adapted from Nichols et al.33). Red circles indicate timepoints selected for transient analysis throughout the manuscript taken from the fourth simulated cardiac cycle.

Mentions: The shear thinning behavior of blood was accounted for using the non-Newtonian “Carreau-Yasuda” model as recommended in the literature.30 Blood density was assumed to be 1050 kg/m.3 An inlet boundary condition of flow rate vs. time (ranging from 0–102 mL/min) was adapted from Nichols et al.33, assuming a heart rate of 75 beats/min (Fig. 1). The bulk Reynolds number (Re) was approximately 80. Due to the simplification of using straight vessel geometries, a parabolic, laminar flow profile was used at the inlet boundary and the entrance length extended by 36 mm (0.06Re × 4 mm vessel diameter) to ensure fully developed flow. A constant static pressure condition was prescribed at the outlet.Figure 1


Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations.

Beier S, Ormiston J, Webster M, Cater J, Norris S, Medrano-Gracia P, Young A, Cowan B - Ann Biomed Eng (2015)

Left main coronary blood flow over time prescribed as the inlet boundary condition (adapted from Nichols et al.33). Red circles indicate timepoints selected for transient analysis throughout the manuscript taken from the fourth simulated cardiac cycle.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764643&req=5

Fig1: Left main coronary blood flow over time prescribed as the inlet boundary condition (adapted from Nichols et al.33). Red circles indicate timepoints selected for transient analysis throughout the manuscript taken from the fourth simulated cardiac cycle.
Mentions: The shear thinning behavior of blood was accounted for using the non-Newtonian “Carreau-Yasuda” model as recommended in the literature.30 Blood density was assumed to be 1050 kg/m.3 An inlet boundary condition of flow rate vs. time (ranging from 0–102 mL/min) was adapted from Nichols et al.33, assuming a heart rate of 75 beats/min (Fig. 1). The bulk Reynolds number (Re) was approximately 80. Due to the simplification of using straight vessel geometries, a parabolic, laminar flow profile was used at the inlet boundary and the entrance length extended by 36 mm (0.06Re × 4 mm vessel diameter) to ensure fully developed flow. A constant static pressure condition was prescribed at the outlet.Figure 1

Bottom Line: Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG.For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts.In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. s.beier@auckland.ac.nz.

ABSTRACT
Stent induced hemodynamic changes in the coronary arteries are associated with higher risk of adverse clinical outcome. The purpose of this study was to evaluate the impact of stent design on wall shear stress (WSS), time average WSS, and WSS gradient (WSSG), in idealized stent geometries using computational fluid dynamics. Strut spacing, thickness, luminal protrusion, and malapposition were systematically investigated and a comparison made between two commercially available stents (Omega and Biomatrix). Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG. Local hemodynamics worsened with luminal protrusion of the stent and with stent malapposition, adverse high WSS and WSSG were identified around peak flow and throughout the cardiac cycle respectively. For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts. In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

No MeSH data available.


Related in: MedlinePlus