Katsumi Ueno

Bio: Katsumi Ueno is an academic researcher from Memorial Hospital of South Bend. The author has contributed to research in topics: Angioplasty & Restenosis. The author has an hindex of 10, co-authored 19 publications receiving 1345 citations.

Considerable Time From the Onset of Plaque Rupture and/or Thrombi Until the Onset of Acute Myocardial Infarction in Humans Coronary Angiographic Findings Within 1 Week Before the Onset of Infarction

Abstract: Background—It has been thought that the thrombi and bleeding in plaques that occur after plaque rupture or endothelial damage from vessels with mild stenosis suddenly occlude the lumen and cause ac...

Difference of Tissue Characteristics Between Early and Very Late Restenosis Lesions After Bare-Metal Stent Implantation: An Optical Coherence Tomography Study

Abstract: Background— Although in-stent restenosis (ISR) after bare-metal stent (BMS) implantation peaks in the early phase, very late (VL) ISR occasionally is observed beyond a few years after BMS implantation. To date, this mechanism has not been fully clarified. Methods and Results— We compared the morphological characteristics of VL-ISR (>5 years, without restenosis within the first year) (n=43) to those of early (E) ISR (within the first year) (n=39) using optical coherence tomography (OCT). Qualitative restenotic tissue analysis included assessment of tissue structure (homogeneous or heterogeneous), presence of microvessels, disrupted intima with cavity, and intraluminal material and was performed at every 1-mm slice of the entire stent. The proportions of cross-sections with heterogeneous intima in the entire stent was significantly higher in the VL-ISR group compared to the E-ISR group (60.5±28.5% versus 5.8±11.5%, P <0.0001), with heterogeneous intima being more frequently observed at the minimum lumen area site in the VL-ISR group (90.7% versus 17.9%, P <0.0001). Disrupted intima with cavity and intraluminal material also were observed more frequently in the VL-ISR group for the entire stent (18.6% versus 0%, 20.9% versus 2.6%, P <0.03) as well as at the minimum lumen area site (13.9% versus 0%,16.2% versus 0%, P <0.03). Conclusions— The morphological characteristics of restenotic tissue in VL-ISR were different from those in E-ISR and similar to atherosclerotic plaque. In BMS, progression of the atherosclerotic process within neointima after stent implantation may be associated with VL-ISR.

Utility of a scoring balloon for a severely calcified lesion: bench test and finite element analysis

Abstract: We aimed to investigate the effectiveness of a scoring balloon catheter in expanding a circumferentially calcified lesion compared to a conventional balloon catheter using an in vitro experiment setting and elucidate the underlying mechanisms of this ability using a finite element analysis. True efficacy of the scoring device and the underlying mechanisms for heavily calcified coronary lesions are unclear. We employed a Scoreflex scoring balloon catheter (OrbusNeich, Hong Kong, China). The ability of Scoreflex to dilate a calcified lesion was compared with a conventional balloon catheter using 3 different sized calcium tubes. The thickness of the calcium tubes were 2.0, 2.25, and 2.5 mm. The primary endpoints were the successful induction of cracks in the calcium tubes and the inflation pressures required for inducing cracks. The inflation pressure required for cracking the calcium tubes were consistently lower with Scoreflex (p < 0.05, Student t test). The finite element analysis revealed that the first principal stress applied to the calcified plaque was higher by at least threefold when applying the balloon catheter with scoring elements. A scoring balloon catheter can expand a calcified lesion with lower pressure than that of a conventional balloon. The finite element analysis revealed that the concentration of the stress observed in the outside of the calcified plaque just opposite to the scoring element is the underlying mechanism of the increased ability of Scoreflex to dilate the calcified lesion.

A Randomized Comparison of Coronary-Stent Placement and Balloon Angioplasty in the Treatment of Coronary Artery Disease

Abstract: Background Coronary-stent placement is a new technique in which a balloon-expandable, stainless-steel, slotted tube is implanted at the site of a coronary stenosis. The purpose of this study was to compare the effects of stent placement and standard balloon angioplasty on angiographically detected restenosis and clinical outcomes. Methods We randomly assigned 410 patients with symptomatic coronary disease to elective placement of a Palmaz-Schatz stent or to standard balloon angioplasty. Coronary angiography was performed at base line, immediately after the procedure, and six months later. Results The patients who underwent stenting had a higher rate of procedural success than those who underwent standard balloon angioplasty (96.1 percent vs. 89.6 percent, P = 0.011), a larger immediate increase in the diameter of the lumen (1.72 ±0.46 vs. 1.23 ±0.48 mm, P<0.001), and a larger luminal diameter immediately after the procedure (2.49 ±0.43 vs. 1.99 ±0.47 mm, P<0.001). At six months, the patients with stented ...

Intracoronary Stenting Without Anticoagulation Accomplished With Intravascular Ultrasound Guidance

Abstract: Background The placement of stents in coronary arteries has been shown to reduce restenosis in comparison to balloon angioplasty. However, clinical use of intracoronary stents is impeded by the risk of subacute stent thrombosis and complications associated with the anticoagulant regimen. To reduce these complications, the hypothesis that systemic anticoagulation is not necessary when adequate stent expansion is achieved was prospectively evaluated on a consecutive series of patients who received intracoronary stents. Methods and Results From March 1993 to January 1994, 359 patients underwent Palmaz-Schatz coronary stent insertion. After an initial successful angiographic result with Conclusions The Palmaz-Schatz stent can be safely inserted in coronary arteries without subsequent anticoagulation provided that stent expansion is adequate and there are no other flow-limiting lesions present. The use of high-pressure final balloon dilatations and confirmation of adequate stent expansion by intravascular ultrasound provide assurance that anticoagulation therapy can be safely omitted. This technique significantly reduces hospital time and vascular complications and has a low stent thrombosis rate.

Anti-angiogenic compositions and methods of use

Abstract: The present invention provides compositions comprising an anti-angiogenic factor, and a polymeric carrier. Representative examples of anti-angiogenic factors include Anti-Invasive Factor, Retinoic acids and derivatives thereof, and paclitaxel. Also provided are methods for embolizing blood vessels, and eliminating biliary, urethral, esophageal, and tracheal/bronchial obstructions.

Arterial Remodeling After Coronary Angioplasty A Serial Intravascular Ultrasound Study

Abstract: Background Restenosis occurs after 30% to 50% of transcatheter coronary procedures; however, the natural history and pathophysiology of restenosis are still incompletely understood. Methods and Results Serial (postintervention and follow-up) intravascular ultrasound imaging was used to study 212 native coronary lesions in 209 patients after percutaneous transluminal coronary angioplasty, directional coronary atherectomy, rotational atherectomy, or excimer laser angioplasty. The external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque plus media (P+M) CSA was calculated as EEM minus lumen CSA. The anatomic slice selected for serial analysis had an axial location within the target lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen (from 6.6±2.5 to 4.0±3.7 mm2, P<.0001) was due to a decrease in EEM (from 20.1±6.4 to 18.2±6.4 mm2, P<.0001); 27% was due to an increase in P+M (from 13.5±5.5 to 14.2±5.4 mm2, P<.0001). ΔLumen CSA correlated mo...