Hemodynamics in Coronary Arterial Tree of Serial Stenoses

Abstract

Serial segmental narrowing frequently occurs in humans, which alters coronary hemodynamics and further affects atherosclerotic progression and plaque formation. The objective of this study was to understand the distribution of hemodynamic parameters in the epicardial left main coronary arterial (LMCA) tree with serial stenoses reconstructed from patient computer tomography angiography (CTA) images. A finite volume method was used in conjunction with the inlet pressure wave and outlet flow resistance. The time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) were determined from the flow field. A stenosis at a mother vessel mainly deteriorated the hemodynamics near the bifurcation while a stenosis at a daughter vessel affected the remote downstream bifurcation. In comparison with a single stenosis, serial stenoses increased the peak pressure gradient along the main trunk of the epicardial left anterior descending arterial tree by > 50%. An increased distance between serial stenoses further increased the peak pressure gradient. These findings have important implications on the diagnosis and treatment of serial coronary stenoses.

Fig 1. Geometrical model reconstructed from CTA (A), computational meshes (B), measured aortic pressure wave (C), TAWSS (D), OSI (E) and flow field (F) in the epicardial LMCA tree of a healthy subject.

The small figures for flow field show the zoomed view.

Fig 2. (A-D) Geometrical model reconstructed from CTA (A), TAWSS (B), OSI (C) and flow field (D) in the epicardial LMCA tree of a representative patient who has area stenosis of 72% and stenotic length of 8.1 mm, area stenosis of 78% and stenotic length of 7.9 mm, area stenosis of 85% and stenotic length of 2.4 mm at three sites; (E-H) geometrical model (E), TAWSS (F), OSI (G) and flow field (H) in the epicardial LMCA tree after suppositional angioplasty (i.e., two area stenoses in the main trunk of epicardial LAD tree were assumed to be restored after angioplasty).

The small figures for TAWSS and OSI show the posterior view. The small figures for flow field show the zoomed view.

Fig 3. In correspondence with Fig 1A, TAWSS and OSI in the epicardial tree that has an idealized 75% area stenosis at the mother vessel (A-B) and at the large daughter vessel (C-D) (stenotic length of 7.0 and 7.3 mm, respectively) in the first bifurcation of LAD arterial tree; TAWSS and OSI in the epicardial tree that has an idealized 75% area stenosis at the mother vessel (E-F) and at the large daughter vessel (G-H) (stenotic length of 8.5 and 8.9 mm, respectively) in the second bifurcation of LAD arterial tree.

The small figures show the posterior view of arteries.

Fig 4. In correspondence with Fig 1A, TAWSS and OSI in the epicardial tree that has two idealized 75% area stenoses at the mother vessel and large daughter vessel (stenotic lengths of 7.0 mm and 7.3 mm) in the first bifurcation of LAD arterial tree (A-B); at the mother vessel in the first and second bifurcations (stenotic lengths of 7.0 mm and 8.5 mm) (C-D); at the mother vessel in the first bifurcation and at the large daughter vessel in the second bifurcation (stenotic lengths of 7.0 mm and 8.9 mm) (E-F); at the large daughter vessel in the first bifurcation and at the mother vessel in the second bifurcation (stenotic lengths of 7.3 mm and 8.5 mm) (G-H); at the large daughter vessel in the first and second bifurcations (stenotic lengths of 7.3 mm and 8.9 mm) (I-J).

The small figures show the posterior view of arteries.

Fig 5. In correspondence with Fig 1A, TAWSS and OSI in the epicardial tree that has an idealized 50% area stenosis of 7.0 mm length at the mother vessel of the first bifurcation and an idealized 75% area stenosis of 8.5 mm length at the mother vessel of the second bifurcation in the LAD arterial tree (A-B); an idealized 50% area stenosis of 7.0 mm length at the mother vessel of the first bifurcation and an idealized 75% area stenosis of 8.9 mm length at the large daughter vessel of the second bifurcation in the LAD arterial tree (C-D); an idealized 50% area stenosis of 7.3 mm length at the large daughter vessel of the first bifurcation and an idealized 75% area stenosis of 8.5 mm length at the mother vessel of the second bifurcation in the LAD arterial tree (E-F); an idealized 50% area stenosis of 7.3 mm length at the large daughter vessel of the first bifurcation and an idealized 75% area stenosis of 8.9 mm length at the large daughter vessel of the second bifurcation in the LAD arterial tree (G-H).

The small figures show the posterior view of arteries.

Fig 6. TAWSS and OSI in the epicardial tree that has an idealized 75% area stenosis at the first bifurcation and an idealized 50% area stenosis at the second bifurcation in the LAD arterial tree corresponding to Fig 5A–5H.

The small figures show the posterior view of arteries.