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Biomedical subjects

Ken Kozuma

Publications and source records attributed to Ken Kozuma.

14 recordsLinked to original sources
PubMed2006

Radiosensitive functional dye: clinical application for estimation of patient skin dose.

Institutional review board approval and informed patient consent were obtained. The purpose of the study was to prospectively evaluate the use of radiosensitive indicators to estimate patient entrance skin dose (ESD). Forty-six patients wore a jacket with 48 or 52 indicators adhered to the back during percutaneous coronary interventions; they had eight additional indicators on their upper arms. The patients' ESDs were calculated according to the change in color of the indicators. There were good correlations between the ESDs estimated by using color measurements performed with an optical instrument and those estimated at visual observation (P < .001) and between the ESDs estimated by using a thermoluminescent dosimeter and those estimated by using color measurements (P < .001). The radiosensitive indicator method seems to be useful for estimating ESDs and their distribution during percutaneous coronary intervention; however, visual observation is reliable for estimating doses of up to 5 Gy only. (c) RSNA, 2006.

Aged↗
PubMed2006

Impact of 16-slice computed tomography in percutaneous coronary intervention of chronic total occlusions.

The main reason for failure of percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is because the calcified plaque prevents the guide wire crossing the occlusion. We aimed to identify the route, and characterize plaque components within CTO, using 16-slice computed tomography (MSCT). Twenty three angiographic CTO in 22 patients (mean age 69 +/- 5 years, 17 males) were included. All patients had undergone MSCT prior to PCI. Images were analyzed for lesion visibility and plaque characteristics of CTO. The presence and location of calcified plaque within the CTO were systematically assessed. Each lesion was classified as a noncalcified, moderately calcified, or exclusively calcified plaque. Procedural failure was defined as the inability to cross a guide wire through the occlusion. All coronary routes of CTO segment were visualized. MSCT revealed three markedly bent CTO segments (13.0%), which could not be identified by coronary angiography only. Calcified plaques were detected in 30 lesions of 19 CTO segments (82.6%), but were not detected in the other four. The majority of calcified plaque was located in the proximal lesion, or both proximal and distal lesions. Fifteen out of 30 calcified lesions (50.0%) were exclusively calcified plaques. Overall procedural success was obtained in 21 CTOs (91.3%). MSCT can accurately identify the route of the CTO segment and evaluate both distribution and amount of the calcified plaque within it. Even with the complicated and/or calcified lesions, PCI success rate was excellent under MSCT guidance. MSCT should become a useful tool in PCI of CTO.

Aged↗
PubMed2006

Radiation exposure to patient's skin during percutaneous coronary intervention for various lesions, including chronic total occlusion.

BACKGROUND: Radiation skin injuries have been reported as a result of various procedures, so in the present study the patients' entrance skin dose (ESD) during percutaneous coronary intervention (PCI) was evaluated. METHODS AND RESULTS: ESDs were assessed during 97 procedures (13 for chronic total occlusion (CTO), 14 for multivessel stenoses, 22 for single-vessel multiple stenoses, and 48 for single stenosis). The patients wore jackets that had 48 or 52 radiosensitive indicators placed on the back during the PCI procedures, with 8 other indicators placed on both upper arms. After the procedure, the color of the indicators was analyzed with a color measuring instrument, and the patients' ESDs were calculated from the color difference of the indicators. The average maximum ESDs of the patients were 4.5 +/- 2.8 Gy (median: 4.6 Gy) for CTO, 2.3 +/- 0.7 Gy (median: 2.4 Gy) for multivessel stenoses, 1.8 +/- 1.0 Gy (median: 1.5 Gy) for single-vessel multiple stenoses, and 1.4 +/- 0.9 Gy (median: 1.2 Gy) for single stenosis. CONCLUSIONS: Skin injury can occur during PCI, especially for CTO, so it is important to estimate each patient's ESD and attempt to reduce it.

Aged↗
PubMed2005

Intravascular ultrasound analysis of the radial artery for coronary artery bypass grafting.

BACKGROUND: The radial artery has become a popular conduit for coronary artery bypass surgery. However, limited information has been provided regarding the atherosclerotic nature of this artery, which may affect both the immediate intraoperative difficulties and long-term graft patency. METHODS: We examined intravascular ultrasound (IVUS) images of the radial artery in patients with coronary artery diseases. Cross sections of the radial artery were assessed using the following factors: lumen diameter, lumen area, vessel diameter, vessel area, plaque area, percent plaque area, and extent of calcium deposition. RESULTS: The IVUS images were obtained from radial arteries of 58 patients (47 men, average 67 +/- 9 years) during transradial procedures; ie, transradial coronary angiography and/or transradial coronary intervention. Mean luminal diameter was 3.28 +/- 0.69 mm and 3.00 +/- 0.70 mm at the proximal and distal segments, respectively, and 2.58 +/- 0.73 mm at the minimal lumen cross section. A percent plaque area greater than 50% was seen in five radial arteries (8.6%) whose average plaque length was 26.4 +/- 30.8 mm. Of these, one showed a plaque length greater than 50 mm, and another showed vessel caliber less than 2.0 mm. Five of 58 radial arteries (8.6%) showed calcium deposition, two of which showed diffuse calcification (> 50 mm). Thus, among 58 radial arteries, four (6.9%: one with diffuse arteriosclerosis, one small radial artery, two with diffuse calcification) were considered unsuitable for bypass conduit. CONCLUSIONS: Preoperative evaluation of the radial artery is recommended in order to prevent unnecessary exploration of the forearm and to improve graft patency.

Aged↗
PubMed2005

Comparison of pharmacokinetics of the sirolimus-eluting stent in Japanese patients with those in American patients.

The aim of this study was to evaluate the pharmacokinetics of the sirolimus-eluting stent (SES) implanted in 20 Japanese patients with angina pectoris and compare it with that in US study. Bx VELOCITY stent loaded with a total sirolimus dose of 150 mug was used in this study. Ten patients were treated by single-SES (group 1) and 10 patients were treated by double-SES (group 2). Sirolimus levels in whole blood were serially measured in the 2 groups after the SES implantation and compared with the pharmacokinetics in US study. We also evaluated the side effect of sirolimus, major adverse clinical events, and binary angiographic restenosis at 8 months after the SES implantation. Peak concentrations were observed approximately 4 hours after the SES implantation, and sirolimus half-lives were approximately 120 hours in each group. Mean peak sirolimus levels were 0.86 and 2.00 ng/mL for the group 1 and group 2, respectively. The peak concentrations of sirolimus in this study were twice higher in Japanese than in Americans, but they were much lower than effective concentration of sirolimus when orally administrated as an immunosuppressive agent. There were no side effects of sirolimus and no binary angiographic restenosis in any patients. One patient had target vessel revascularization at 8 months after the SES implantation. Although blood concentrations of sirolimus in Japanese patients after SES implantation are somewhat higher than those in American patients, its level is extremely low compared with the systemic administration, indicating the same clinical benefits by the SES could be safely expected in Japanese patients.

Adult↗
PubMed2005

Angiographic and clinical outcomes of a pharmacokinetic study of sirolimus-eluting stents: lesson from restenosis cases.

BACKGROUND: A pharmacokinetic (PK) study was conducted to evaluate sirolimus-eluting stents (SES) in Japanese people, representing the first clinical trial of the use of drug-eluting stents in Japan. METHODS AND RESULTS: The PK study was conducted in 20 patients with 30 lesions treated with sirolimus-coated BX Velocity stents. All lesions were treated with a single SES (3 x 18 mm). Angiographic follow-up was performed at 8 months after SES implantation, and the clinical outcomes were evaluated at 1 year in all cases. All procedures were successful, and all patients were discharged without any adverse cardiac events. The total restenosis rate was 10% (3 lesions) and target vessel revascularization was performed in those 3 cases (15%). Restenoses occurred at the proximal and distal stent margins. Intravascular ultrasound examination of restenosis cases revealed abundant plaque burden at the stent edges even though the luminal area was preserved. CONCLUSIONS: The sirolimus-eluting BX Velocity stent is safe and useful for Japanese patients with coronary artery disease. However, restenosis at proximal stent edge seems to be a problem.

Aged↗
PubMed2005

[Cardiac rupture caused by myocardial infarction in the diagonal branch area: evaluation by cardiac multislice computed tomography: a case report].

A 75-year-old woman was admitted to the emergency room because of hypotension and loss of consciousness induced by cardiac tamponade. Electrocardiography revealed ST elevation and laboratory data showed elevation of serum creatine kinase and troponin I. The patient was referred to the cardiology department 5 days later. Cardiac catheterization revealed ventricular aneurysm in the anterior wall, significant stenosis (75%) in the left anterior descending coronary artery and subtotal stenosis (99%) in the diagonal branch. Cardiac multislice computed tomography suggested that the ventricular pseudoaneurysm was probably due to cardiac rupture caused by myocardial infarction in the diagonal area. Subsequently, aneurysmectomy and coronary artery bypass graft surgery were performed. Cardiac multislice computed tomography is useful for evaluating coronary artery and cardiac rupture.

Aged↗
PubMed2003

The black hole: echolucent tissue observed following intracoronary radiation.

AIMS: Recent trials in humans have given us insight into some of the consequences of intracoronary radiation. The authors describe a new observation noted on intravascular ultrasound: that of intraluminal echolucent tissue, dubbed the 'black hole', noted at six-month follow-up. METHODS AND RESULTS: One hundred and twenty-eight consecutive patients enrolled in brachytherapy protocols were analyzed. The control group (C) consisted of individuals who underwent percutaneous transluminal coronary angioplasty with (n = 48) and without (n = 22) stent implantation. Radiation groups included those who underwent low activity (LA) (n = 18), high activity (HA) (n = 26) and cold-end (CE) (n = 18) radioactive stenting. The Novoste Betacath (n = 39) and Guidant (n = 27) catheter-based radiation systems were also employed. At six-month follow-up echolucent tissue was identified in a total of 28 cases (22%). Angiographic restenosis occurred in 17 cases (61%). No echolucent tissue was seen in the control group or in the LA group. HA and CE radioactive stents were most commonly associated with echolucent tissue. Echolucent tissue was seen in all groups treated with catheter-based radiation with and without stenting. Pathology after atherectomy demonstrated smooth muscle cells scattered in extracellular matrix containing abundant proteoglycans and an absence of elastin and mature collagen. CONCLUSIONS: Echolucent tissue is common after radioactive stenting. It is composed of tissue rich in proteoglycans while poor in mature collagen and elastin.

Angioplasty, Balloon, Coronary↗
PubMed2003

Early detection of doxorubicin-induced myocardial damage by ultrasound tissue characterization with integrated backscatter.

Doxorubicin (DXR) is one of the most effective antineoplastic agents, but its use is limited by its myocardial toxicity. Myocardial injury reduces the cyclic variation of integrated backscatter (CV-IBS) and so the present study was designed to investigate whether CV-IBS can be used to detect the early phase of myocardial damage in patients receiving DXR. Thirty-four subjects constituted the study population, none of whom showed clinically evident heart failure. CV-IBS was obtained for both the interventricular septum and the left ventricular posterior wall in the parasternal short-axis view. Standard echographic measures of left ventricular function were also made. Subjects without DXR exposure or evident cardiac diseases served as controls. The total dose of DXR administered per patient was 339+/-164 mg/m2 (range: 95-680 mg/m2). Conventional echographic parameters, including left ventricular wall thickness, dimensions, fractional shortening, and ejection fraction, showed no significant differences between the 2 groups. In contrast, CV-IBS was significantly decreased in the DXR group compared with the control group (septum: 4.7+/-1.7 vs 7.2+/-1.9 dB, p<0.0001; posterior wall: 6.7 +/-2.2 vs 8.0+/-1.6 dB, p<0.05). CV-IBS can be used as an early indicator of DXR-induced myocardial damage in patients demonstrating normal left ventricular systolic function.

Adult↗
PubMed2003

Sensitivity and specificity of QCA in detecting coronary arterial remodeling after intracoronary brachytherapy: a comparison to serial volumetric three-dimensional intravascular ultrasound analysis. Can we detect positive remodeling by luminography?

BACKGROUND: After treatment with intracoronary brachytherapy, enlargement of lumen (negative late loss) at follow-up has been demonstrated. The aim of the study is to analyze the sensitivity and specificity of quantitative coronary angiography (QCA) parameters to detect a positive vessel remodeling after intracoronary -radiation as compared to intravascular ultrasound (IVUS). METHODS: Twenty-seven patients (27 vessels) treated with balloon angioplasty followed by catheter-based intracoronary -radiation with a (90)Strontium/(90)Yttrium source were assessed by both QCA and three-dimensional IVUS with electrocardiogram-gated pullback. Irradiated segments were analyzed over the total treatment length and in subsegment lengths of 5 mm. RESULTS: Change in minimum luminal diameter (MLD) was not a predictor for the positive remodeling in either total irradiated segments or 5 mm subsegments, with a 54.3% ROC curve area [95% confidence interval (CI), 30-79%], sensitivity of 39% and specificity of 44% (p = not significant) in the total irradiated segments and a 55.9% ROC curve area (95% CI, 46-66%), sensitivity of 55% and specificity of 54% (p = not significant) in the 5 mm subsegments. Changes in mean and maximal lumen diameter were not significant parameters to detect positive vessel remodeling. When only central subsegments were analyzed, change in MLD was a significant predictor, with a 63.3% ROC curve area (95% CI, 52-75%), sensitivity of 55% and specificity of 64% (p = 0.029). CONCLUSION: Lumen enlargement detected by QCA does not reliably indicate a positive vessel remodeling after intracoronary radiation. IVUS analysis may be necessary to investigate the mechanism of restenosis after balloon angioplasty followed by catheter-based radiation.

Angioplasty, Balloon, Coronary↗
PubMed2002

High shear stress after successful balloon angioplasty is associated with restenosis and target lesion revascularization.

BACKGROUND: Vascular wall shear stress (WSS) has been implied in the pathogenesis of atherosclerosis and vascular remodeling. Our aim was to calculate WSS after balloon angioplasty and evaluate its predictive value for long-term outcome. METHODS: WSS was calculated proximal to, in, and distal to the lesion after angiographically successful balloon dilatation and at follow-up with the Hagen-Poiseuille formula (WSS = 4 microQ/piR3) in 202 patients. Volumetric blood flow (Q) and lumen radius (R) were derived from Doppler scanning velocities and videodensitometric cross-sectional areas. RESULTS: Postprocedural proximal and in-lesion values were higher in vessels that developed restenosis (n = 72; 1.22 +/- 0.61 N/m2 and 3.61 +/- 2.38 N/m2, respectively) than in those without restenosis (n = 130, 1.05 +/- 0.51 N/m2 and 2.46 +/- 1.39 N/m2, respectively; P <.05). In-lesion WSS was revealed to be predictive of restenosis by means of logistic regression analysis (odds ratio [OR] = 1.42, P <.05), whereas WSS of the proximal segment was associated with an increased rate of target lesion revascularization (OR = 2.33, P <.005). In the multivariate regression model, WSS of the proximal segment was the only independent predictor when entered with known predictors such as diameter stenosis and coronary flow reserve (OR = 2.15, P <.05). CONCLUSIONS: WSS in the lesion after balloon angioplasty is predictive of angiographic restenosis. Moreover, the proximal value is an independent predictor of target lesion revascularization. This study opens perspectives for the on-line use of WSS as a combined parameter of anatomy and physiology to assess the necessity of adjunctive therapy after successful balloon dilatation.

Angina Pectoris↗
PubMed2002

Modulation of oxidative burst of neutrophils by doxycycline in patients with acute myocardial infarction.

We investigated to what extent doxycycline hydrochloride (DOXY) can modify polymorphonuclear leucocyte (PMN) activity in patients with acute myocardial infarction (AMI). PMN activity was measured in blood samples obtained at 0, 15, 30 and 60 min after DOXY administration. In patients receiving saline, PMN activity did not change over 60 min. In contrast, patients receiving DOXY showed a > or = 10% reduction in PMN activity at 30 and 60 min. These data support the use of DOXY to reduce myocardial cell damage by PMNs in patients with AMI.

Aged↗
PubMed2001

Why and how to avoid stenting during brachytherapy.

Intracoronary radiation is a promising therapy to reduce restenosis after percutaneous coronary intervention. It may be anticipated that radiation and intracoronary stents - the current standard coronary revascularization procedure - have a synergic antirestenosis effect. However, this potential benefit has not been proven in the clinical scenario. Indeed, this combined approach (stenting plus brachytherapy) may even be harmful. Delayed endothelialization and late stent malapposition are important drawbacks of implanting a metallic prosthesis in the setting of radiation therapy. Owing to the relatively high frequency of late thrombosis after stenting irradiated coronary arteries, the Food and Drug Administration required that the labeling of both gamma- and beta-radiation devices recently approved for clinical use explicitly advise avoidance of the placement of new stents. The pathophysiologic aspects as well as the clinical implications of the implantation of a new stent in association with radiation delivered by radioactive stents or catheter-based systems are discussed in this paper.

Journal Article↗