Tatsuhiro Fujimura

Localized elevation of shear stress is related to coronary plaque rupture: a 3-dimensional intravascular ultrasound study with in-vivo color mapping of shear stress distribution.

OBJECTIVES The purpose of the present study was to assess the relationship between shear stress distribution and coronary plaque rupture by means of a new color-mapping program of shear stress with 3-dimensional intravascular ultrasound (IVUS). BACKGROUND Various in-vitro studies have demonstrated that shear stress of the vascular lumen is one of the important determinants of coronary plaque vulnerability. However, the in-vivo relationship between shear stress and plaque rupture is still unclear. METHODS In the present study, 3-dimensional IVUS was used to obtain spatial information on luminal geometry from 20 patients with acute coronary syndrome having a distinct ulcerative lesion. These 3-dimensional contours for each lumen were first reconstructed into mesh polygons, and then analyzed by means of a program for calculating the fluid dynamics. The flow was considered to be a constant laminar one. Then, colorized mappings of the distribution of the streamline, blood pressure, and shear stress were performed. The original luminal contour for each ruptured lesion was obtained by smoothing and extrapolation. RESULTS All patients had a coronary plaque rupture in the proximal or top portion of the plaque hill. In the color mapping, localized elevation of blood pressure and shear stress could be observed on each plaque surface. The shear stress concentration was frequently correlated with the plaque rupture site (kappa = 0.79). CONCLUSIONS Although the absolute value of shear stress is not sufficient to directly provoke mechanical destruction of the fibrous cap, localized high shear stress might be a trigger of fibrous cap rupture.

Late giant coronary aneurysm associated with a fracture of sirolimus eluting stent: A case report

A 73-year-old female underwent percutaneous coronary intervention (PCI) because of stable angina. An elective PCI for the RCA lesion was first performed with deploying sirolimus eluting stents (SES). Three weeks later, PCI was also provided in the residual LAD lesion. Eight months later, she presented with new angina. CAG revealed an in-stent restenosis in the mid LAD and a large eccentric saccular coronary aneurysm (17 mm x 9 mm) at the proximal RCA. Intravascular ultrasound (IVUS) showed absence of stent struts around the orifice of aneurysm, which suggested a fracture of SES stent. The entry of coronary aneurysm was finally sealed with a polytetrafluoroethylene-covered stent. This report documented a rare case of late giant coronary artery aneurysm associated with a fracture of SES.

Serial changes in the three-dimensional aspect of the side-branch ostium jailed by a drug-eluting stent assessed by optical coherence tomography

The present study investigated serial changes in the three-dimensional (3D) aspect of the jailed side-branch (SB) ostium. We evaluated 32 patients who underwent examination with optical coherence tomography (OCT) both at baseline and at follow-up. After reconstruction of the 3D images, we classified the configuration of overhanging struts at the SB orifice into three groups according to the 3D aspect of the jailing configuration. The number of compartments divided by the stent strut was counted. The side-branch flow area (SBFA), i.e., the area of the SB ostium except for jailing struts, was measured by cut-plane analysis. Forty-eight SBs of 25 patients were analyzed. Thirteen SBs were classified as the No-jail type (N-type), 19 as the Simple-jail type (S-type; no longitudinal link at the carina), and 16 as the Complex-jail type (C-type; had a link at the carina). In the N-type, the SBFA was significantly increased at follow-up (P = 0.018). In the C-type, the SBFA was significantly decreased at follow-up (P = 0.002). Percent reduction of SBFA in the C-type group was significantly greater than that in the N-type or S-type groups (S-type vs. C-type P = 0.002, N-type vs. C-type P < 0.001). 3D-OCT images showed that some of the compartments were filled with tissue. The number of compartments was significantly decreased at follow-up (P < 0.001). In the C-type group, the SBFA was significantly decreased and small compartments were filled with tissue. These findings suggest that stent jail complexity is associated with the progression of SB ostial stenosis.

Three-dimensional reconstruction of optical coherence tomography for improving bifurcation stenting

Coronary bifurcation lesions are encountered in approximately 15–20% of all percutaneous coronary interventions (PCIs) [1]. Bifurcation PCI has historically been associated with lower procedural success rates and higher long-term adverse event rates compared with PCI for non-bifurcation lesions. In the drugeluting stent (DES) era, the clinical outcomes for bifurcation PCI have improved considerably [2]. However, bifurcation stenting is still technically challenging and associated with an increased risk of stent thrombosis [3]. The conventional coronary stent is a small mesh-patterned tube, usually linear in shape. To adapt the DES for morphological variation of bifurcation, various techniques have been developed [4]. Although a simple single stent technique has been generally recommended, a complex technique is occasionally required. However, it is not clear which technique is appropriate for each bifurcation lesion. Moreover, even when angiographic results after stent implantation are satisfactory at a glance, unapposed struts, which can potentially cause stent thrombosis, are unobservable with angiography and poorly visible with intravascular ultrasound (IVUS). In order to elucidate such interaction between stent and vessel wall in bifurcation stenting, many bench tests and computer simulations have been performed and useful findings have been reported. However, we could not understand them during procedures in each case. Intravascular optical coherence tomography (OCT) is a lightbased imaging modality, which provides high-resolution images of the coronary arteries. With its unrivaled high resolution (10–15 mm) compared with IVUS (100–150 mm), OCT can evaluate the interaction between the coronary artery and the implanted stent. Viceconte et al. reported that unapposed struts at side branch ostium were frequently observed after bifurcation stenting and that the prevalence of unapposed struts in a two stent technique was significantly greater than that in a single stent technique [5]. Recently developed optical frequency domain imaging (OFDI) and Fourier/frequency-domain OCT (FD-OCT) systems can obtain cross-sectional OCT images of the coronary

New quantitative method to diagnose coronary in-stent restenosis by 64-multislice computed tomography.

BACKGROUND The aim of this study is to evaluate the accuracy of a newly developed quantitative method using 64-multislice computed tomography angiography (CTA) to detect coronary in-stent restenosis (ISR). METHODS AND RESULTS CTA was performed in 45 patients who underwent stent implantation (79 lesions) and the accuracy to diagnose ISR was evaluated by comparing with invasive coronary angiography (ICA). CTA was evaluated both visually and quantitatively using a new stent restenosis index (SRI) utilizing CT densities at proximal and distal artery lumen from the stented region and the correction value depending on the stent diameter. ICA showed 11 ISR (14%). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for visual evaluation were 78%, 75%, 35%, 95%, and 76%, respectively. On the other hand, the quantitative evaluation using SRI represents 82%, 93%, 64%, 97%, and 91%, respectively. CONCLUSIONS Evaluation of ISR using SRI is superior to the visual estimation of CTA.

Feasibility and usefulness of three-dimensional optical coherence tomography guidance for optimal side branch treatment in coronary bifurcation stenting

BACKGROUND For the treatment of coronary bifurcation lesions, optimal guidewire (GW) recrossing after main vessel stenting is important for good stent apposition at the side branch (SB) orifice in kissing balloon inflation (KBI). METHODS We analyzed 150 bifurcation lesions treated with single stenting following KBI in the three-dimensional optical coherence tomography (3D-OCT) bifurcation registry study (2015-16) and a single center experience (2012-16). OCT examination was performed after GW recrossing to the SB and after KBI. Patients were divided into two-dimensional (2D, n=78) and 3D groups (n=72) according to 2D- or 3D-OCT guidance. GW recrossing position, jailing configuration of the stent over the SB (divided into Link-connecting type: stent link connecting to the carina and Link-free type: no stent link at the carina) and stent apposition were compared between the groups. RESULTS Distal GW recrossing was achieved in 75.6% and 91.7% in the 2D and 3D groups, respectively (P=0.004). Compared with the 2D group, the incidence of incomplete stent apposition (ISA) toward the SB in the 3D group tended to be lower in the whole cohort (14.5±13.6% vs 10.0±9.0%, P=0.077), and was significantly lower in left main trunk bifurcations (18.7±12.8% vs 10.3±8.9%, P=0.014). Independent contributors to ISA were the Link-connecting type (β 0.089, P<0.001), distal GW recrossing (β -0.078, P=0.001), and age (β -0.0020, P=0.012). CONCLUSION Optimal GW recrossing under 3D-OCT guidance is feasible and improves stent apposition, which may lead to a better clinical outcome in the treatment of bifurcation lesions.

Serial changes in the side-branch ostial area after main-vessel stenting with kissing balloon inflation for coronary bifurcation lesions, assessed by 3D optical coherence tomography

Aims We evaluated the influence of the jailing configuration and guidewire rewiring position in front of the side-branch (SB) ostium before kissing balloon inflation (KBI) against side-branch ostial area (SBOA) at follow-up using 3D optical coherence tomography (3D-OCT). Methods and results We retrospectively analysed the cases of the 37 consecutive patients who underwent main-vessel (MV) stenting with KBI for coronary bifurcation lesion under OCT guidance and the follow-up OCT 6-12 months. We divided the patients into two groups, considering both the jailing configuration and the rewiring position by 3D-OCT. We defined the cases that achieved both the distal rewiring and link-free carina configuration as the FCD group, and the other cases were defined as the Non-FCD group. We compared the differences in the SBOA derived by the cut-plane analysis and the number of compartments between the two groups. The median and interquartile range of serial change and percent serial change in SBOA in the FCD group were significantly larger than those in the Non-FCD group [0.43 mm2 (-0.29 to 0.91) vs. -0.65 mm2 (-1.33 to 0.34); P = 0.0136 and 9.47% (-8.37 to 27.33) vs. -13.77% (-31.64 to 10.88); P = 0.0182]. Conclusion This serial OCT study demonstrated that the achievement of both the distal rewiring and link-free carina configuration may be important for the preservation of the SBOA after MV stenting with KBI for coronary bifurcation lesions.

Data on two- and three-dimensional optical coherence tomography guidance for the treatment for the bifurcation lesion

This article comprised the data related to the research article entitled “Feasibility and usefulness of three-dimensional optical coherence tomography guidance for optimal side branch treatment in coronary bifurcation stenting” (Nagoshi et al., In press) [1]. In this article we reports details about two patterns of guide wire (GW) recrossing position after crossover stenting in bifurcation lesion classified with three-dimensional optical coherence tomography (3D-OCT) (Okamura et al., 2014) [2] and follow-up data about the treatment with percutaneous coronary intervention(PCI) for bifurcation lesion in terms of the two- (2D) or 3D-OCT guidance. Subgroup analysis about differences in the parameters between the proximal and the distal GW recrossing patterns are analyzed here.

In vitro assessment of six aspiration catheters using a distal protection filter

BACKGROUND We assessed performance of 6 aspiration catheters for distal embolization using a distal protection filter in an in vitro experiment. In acute myocardial infarction, a distal protection filter is used for lesions likely to induce a distal embolism. Which aspiration cathether is most effective when used with a distal protection filter remains still unclear. METHODS A 0.5-cm3 bolus of gelatin as a model of stagnant pools of coronary plaque debris was captured in the distal protection filter and aspirated by 6 aspiration catheters. We measured and compared the length of the suspended embolus matter. RESULTS Among the 6 catheters evaluated, the use of the Export Advance catheter (Medtronic) resulted in significantly shorter lengths of the suspended embolus matter compared to the use of the TVAC II (Nipro), Thrombuster III SL (Kaneka), and Rebirth Pro (Goodman) catheters (p < 0.01). The residual embolus matter in all cases had drained distally to the distal protection filter when the filter was retrieved. CONCLUSIONS The use of the Export Advance catheter showed better performance using a distal protection filter in this in vitro experiment, and its use might be more effective in preventing distal embolisms in combination with a distal protection filter.