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.

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.

[Current status and perspectives of coronary imaging for patients with diabetes mellitus].

Diabetes mellitus (DM) is an independent and distinct risk factor of ischemic heart disease. Therefore, early identification and management of coronary atherosclerosis for patients with DM is being desired. For the purpose of visualizing coronary atherosclerosis, various imaging modalities have been proposed especially to identify an unstable plaque that has a thin fibrous cap and a large lipid core. These modalities include intravascular ultrasound, coronary angioscopy, intracoronary thermography, optical coherence tomography, multi-slice CT, MRI, and so on. The development of these modalities are now pushing all cardiologists to get interested in a new field called as "plaque imaging".

Longitudinal structural determinants of atherosclerotic plaque vulnerability: a computational analysis of stress distribution using vessel models and three-dimensional intravascular ultrasound imaging.

OBJECTIVES: This study theoretically examined the longitudinal structural determinants of plaque vulnerability using a color-coded stress mapping technique for several hypothetical vessel models as well as three-dimensional intravascular ultrasound (IVUS) images with use of a finite element analysis. BACKGROUND: It has been shown that an excessive concentration of stress is related to atherosclerotic plaque rupture. However, the local determinants of in-plaque longitudinal stress distribution along the coronary arterial wall remain unclear. METHODS: Using a finite element analysis, we performed a color mapping of equivalent stress distribution within plaques for three-dimensional vessel models as well as longitudinal IVUS plaque images (n = 15). Then, the effects of plaque size, shape, expansive remodeling, calcification, and lipid core on the equivalent stress distribution were examined. RESULTS: The color mapping of vessel models revealed a concentration of equivalent stress at the top of the hills and the shoulders of homogeneous fibrous plaques. Expansive remodeling and the lipid core augmented the surface equivalent stress, whereas luminal stenosis and superficial calcification attenuated the equivalent stress. The location of excessive stress concentration was modified by the distribution of the lipid core and calcification. The thickness of the fibrous cap was inversely related to the equivalent stress within the fibrous cap. However, the color mapping of IVUS plaque images showed that the equivalent stress value at the fibrous cap varied with changes in plaque shape and superficial calcification, even when the thickness of the fibrous cap remained constant. CONCLUSIONS: A distribution analysis of longitudinal stress revealed specific effects of plaque shape, size, and remodeling, as well as effects of the interior distribution of tissue components, on the concentration of stress at the plaque surface. Moreover, fibrous caps of the same thickness did not consistently represent the same vulnerability to rupture.