Ex vivo assessment of neointimal characteristics after drug-eluting stent implantation: Optical coherence tomography and histopathology validation study.

BACKGROUND: Optical coherence tomography (OCT) is one of the tools trying to distinguish neoatherosclerosis from other neointimal tissue but its role has to be still validated. This study evaluated the diagnostic accuracy of OCT for characterization of lipid-atherosclerotic neointima following drug-eluting stent (DES) implantation. METHODS: Twelve stented coronary arteries from the 7 autopsy hearts were imaged by OCT. These OCT images were compared with histology. By OCT, the morphological appearances of neointima were classified into three patterns: homogeneous pattern, heterogeneous pattern with visible strut, or heterogeneous pattern with invisible strut. RESULTS: Of 21 histological cross-sections, 6 were categorized as homogeneous patterns (29%), 11 as heterogeneous patterns with visible stent strut (52%), and 4 as heterogeneous patterns with invisible stent strut (19%). All homogeneous patterns were composed of smooth muscle cells with collagen fibers. The heterogeneous patterns with visible stent strut included proteoglycan-rich myxomatous matrix and calcium deposition. On the other hand, the heterogeneous patterns with invisible stent strut comprised atheromatous tissue, including a large amount of foam cell accumulation (25%) or large fibroatheroma/necrotic core (75%) inside the stent struts within neointima. The optical attenuation coefficient was highest in the heterogeneous pattern with invisible stent strut due to scattering of light by atheromatous tissue. CONCLUSION: The heterogeneous patterns with invisible stent strut on OCT imaging identify the presence of lipid-atherosclerotic tissue within neointima after DES. This may suggest the potential capability of OCT based on visualization of stent struts for discriminating atheromatous formation within neointima from other neointimal tissue.

Assessment of lower limb flow and adequate intra-arterial papaverine doses to achieve maximal hyperemia in elder subjects.

Previous studies reported that invasive physiological assessment for significance of the lesions in the patients with claudication under the condition of pharmacological hyperemia was important to identify the patients who will benefit from revascularization. However, the maximal hyperemic response in lower limb and the method to induce maximum dilatation of vascular bed in lower limb were not well established. The aim of this study was to investigate the range of maximal hyperemic response in lower limb of the normal subjects and to identify the ideal lower limb vasodilatory stimulation. Twelve limbs without stenotic lesions from 12 subjects (average age: 72 ± 6 years) were analyzed. Thermodilution-derived mean transit time (Tmn) was obtained at baseline and during pharmacological hyperemia with incremental dose of intra-arterial papaverine (10, 20, 30, and 40 mg) using a 0.014-inch pressure/temperature sensor-tipped wire in the superficial femoral artery (SFA). Percent increase in blood flow (%IBF) of lower limb was defined as the ratio between baseline Tmn and hyperemic Tmn. Mean ankle brachial index score of the subjects was 1.14 ± 0.09. The %IBF values were enhanced by papaverine in a dose-dependent manner. A dose of 30 mg of intra-arterial papaverine was sufficient to achieve maximum hyperemia (%IBF: range 219-769 %). In conclusion, the increase in blood flow of lower limb during maximal hyperemia varied between individuals and maximal hyperemia can be achieved with 30 mg of papaverine for the SFA lesion.