| Background:Coronary artery bifurcation lesion is a complex lesion subset of coronary disease. Bifurcation lesion treatment is still at the exploratory stage due to higher rates of restenosis, target lesion revascularization and target vessel revascularization. There is lack of evidence to demonstrate the advantage of one approach over the other. Notably,double-stent are required in some circumstances. No matter what kind of double-stent techniqueutilized for coronary bifurcation lesions, there is alwaysa gap without stent struts covering on the carina side of side branch. Bench tests and a couple of clinical researches had proved that endothelial shear stress is one of the important hemodynamic factors associated with the appearance and progression of atherosclerotic disease. Endothelial shear stress is correlated with the neointimal proliferation following stent implantation in the coronary artery. However, endothelial cell function and hemodynamic change in endothelial shear stress at coronary bifurcation site treated by different stenting techniques have rarely been reported.Object:The present study aimed to investigate the differences ofendothelial shear stress distribution and endothelial cell function at coronary bifurcation sites following different stening techniques.Methods: 1. Bench test: Stent implantation withprovisional stenting, classic crush, DK crush and culotte stenting techniques were performed in the silicone simulation model of bifurcation vessels with different bifurcation angles. The whole processes were recorded by a micro-focus camera.2. Experimental study: Twenty mongrel dogs were randomly divided into 2 groups(DK crush versus classic crush). 3-D reconstruction from coronary angiography, coronary velocity measurement via Doppler wire at proximal coronary artery and coronary pressure measurementvia pressure wire at the distal main branch and side branch were performed pre- and post-PCI, and at 6-month follow-up, respectively. Then enodthelial shear stress was calculated using the finite volume method via the CD STAR-CCM + software system. All dogs were sacrificed after 6-month follow-up, endothelial cells were observed in HE staining, e NOS m RNA activity was measured by RT-PCR determination. 3. Clinical study: Eighty-one patients with true bifurcation lesions treated with DK crush or provisional stenting who had 3-D model reconstruction were studied. The bifurcation vessels were divided into main vessel(MV), main branch(MB), side branch(SB), and polygon of confluence(POC). MB and SB were classified by internal- and lateral-subsegments, respectively.Enodthelial shear stress was calculated using the finite volume method via the CD STAR-CCM + software system.Results: 1. Bench test: Bifurcation angle is an important anatomic element in making a decision as to which double stenting technique. In T type bifurcation model gap will be left at the distal carina after double stenting techniques among which DK crush stenting could minnize the size of gap. 2. Experimental study: DK crush was associated with a unique increasing of the ESS and improvement of turbulent flow and reduction of ESS gradient of POC and gap which result in upating the expression of e NOS m RNA.3. Clinical study: The baseline magnitude of ESS in proximal MV, POC-MV, POC-MB, POC-SB and MB-internal segments increased significantly, compared to MB-lateral, SB-internal and SB-lateral. DK crush had the potential of uniformly reducing ESS, turbulent index and the ESS gradient. The ESS value at the POC-SB and SB in the one-stent group remained higher. The turbulent index in SB-lateral segment and ESS gradient between the POC-SB minus the SB-lateral had equal predictive values for in-stent restenosis.Conclusion: Compared to classic crush and provisional stenting, DK crush was associated with minimizing of gap size which result in improvement of turbulent flow, reduction of ESS gradient and further updating the expression of e NOS m RNA.
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