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.
R Studio 8.9 Serial
The objective of this study is to determine the distribution of hemodynamic parameters in patient-specific epicardial left main coronary arterial (LMCA) tree with serial stenoses varying from mild to moderate. The three-dimensional (3D) geometry of patient epicardial LMCA tree was reconstructed from computer tomography angiography (CTA) images. Navier-Stokes and continuity equations were solved using a transient finite volume method. The inlet and outlet boundary conditions were the aortic pressure wave and flow resistance, respectively. Hemodynamic parameters including TAWSS and OSI were determined based on the computed flow field. The significance and limitations of the study were enumerated.
Serial stenoses at mother vessels of the first and second bifurcations decreased TAWSS, increased OSI, and extended atherosclerosis-prone zones near its own bifurcation in the LAD arterial tree, but had relatively small effects on each other, as shown in Figs 4C, 5A and 6A. Similarly, serial stenoses at daughter vessels of the first and second LAD bifurcations had relatively small effects on each other, as shown in Figs 4I, 5G and 6G. There was negligible interaction between serial stenoses at the mother vessel in the first bifurcation and at the daughter vessel in the second bifurcation, as shown in Figs 4E, 5C and 6C. Serial stenoses at the daughter vessel in the first bifurcation and at the mother vessel in the second bifurcation showed strong interaction similar to serial stenoses at a bifurcation. On the other hand, the increased distance between serial stenoses along the LAD main trunk reduced the interaction between them and resulted in the increase of peak pressure gradient, i.e., from case 5 to case 9, from case 10 to case 13 and from case 14 to case 17 in Table 2, which agreed with clinical observations [28].
A key finding of the study was to show the increased hemodynamic interaction of serial stenoses along the main trunk of LAD as the distance between them was reduced. Interventional cardiologist requires to consider the interaction for the diagnosis and treatment of serial coronary stenoses. For example, the fractional flow reserve (i.e., ) has been proposed to assess the hemodynamic significance of a coronary stenosis [22, 23]. For serial stenoses in Figs 4G, 5E and 6E, after a primary stenosis was treated, the hemodynamic environment of an untreated stenosis was altered such that the corresponding FFR should be reassessed. For serial stenoses in Figs 5C and 6C, a single pullback pressure recording determined the FFR through each stenosis given the negligible interaction between them.
Another key finding was that serial moderate stenoses at mother and daughter vessels of a coronary bifurcation enhanced the hemodynamic conditions near the bifurcation as compared with a single stenosis. The two key findings suggest that a long stent placement should be selected to cover the serial stenoses in Fig 4A when FFR
Serial moderate stenoses along the LAD main trunk increased the peak pressure gradient by > 50% in comparison with a single stenosis, where the increased distance between serial stenoses increased the peak pressure gradient. Moreover, a stenosis at a mother vessel was found to mainly worsen the hemodynamic distribution near the bifurcation while a stenosis at a daughter vessel affected the remote downstream bifurcation. For serial stenoses, the downstream stenosis enhanced the hemodynamics impaired by the upstream stenosis, but the proximal and distal sites to the downstream stenosis had lower TAWSS and higher OSI. The hemodynamic analysis in multiple stenoses of the epicardial coronary arterial tree improves our understandings of diffuse atherosclerotic progression. 2ff7e9595c
Comments