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Biomedical subjects

Toru Kataoka

Publications and source records attributed to Toru Kataoka.

14 recordsLinked to original sources
PubMed2006

Influence of plaque calcium on neointimal hyperplasia following bare metal and drug-eluting stent implantation.

OBJECTIVES: To examine the influence of vessel wall calcium on neointimal hyperplasia (NIH) following bare metal stent (BMS) and drug-eluting stent (DES) implantation. BACKGROUND: While procedural complications with coronary stenting in calcified lesions are well reported, little is known about subsequent NIH on plaque calcium following either BMS or DES implantation. METHODS: In the Study to COmpare REstenosis Rate between QueST and QuaDDS-QP2 (SCORE) trial, 6 months follow-up volumetric intravascular ultrasound data were available for 41 lesions (BMS, 19; DES, 22). NIH thicknesses on superficial, deep, and noncalcified plaque were calculated at every 0.5 mm intervals over the stented segment. Calcified and less-calcified cross-sections were defined as those containing arcs of plaque calcium > or = 90 degrees and < 90 degrees , respectively. RESULTS: In BMS, mean NIH thickness on both superficial (0.24 +/- 0.23 mm) and deep calcium (0.25 +/- 0.21 mm) was significantly smaller than that of noncalcified plaque (0.31 +/- 0.22 mm) (P < 0.0005). NIH area was significantly smaller in calcified cross-sections compared to less-calcified cross-sections (2.1 +/- 1.2 mm2 vs. 3.1 +/- 1.9 mm2, P < 0.0001). While in contrast, in DES, mean NIH thickness was similar, irrespective of the presence or location of calcium (0.03 +/- 0.05 mm vs. 0.03 +/- 0.06 mm vs. 0.03 +/- 0.05 mm, superficial vs. deep vs. noncalcified plaque, P = NS). NIH area was also similar between calcified and less-calcified cross-sections (0.3 +/- 0.6 mm2 vs. 0.3 +/- 0.6 mm2, P = NS). CONCLUSIONS: These results suggest that while plaque calcium may influence NIH following BMS implantation, NIH suppression using DES does not appear to be affected by the presence or location of calcium.

Bridged-Ring Compounds↗
PubMed2006

Acute myocardial infarction: clinical characteristics and plaque morphology between expansive remodeling and constrictive remodeling by intravascular ultrasound.

BACKGROUND: According to recent intravascular ultrasound (IVUS) studies, expansive remodeling (ER) at the culprit lesion has been observed in almost 50% of patients with acute coronary syndrome and constrictive remodeling (CR) in 30%. The purpose of this study is to investigate the difference between ER and CR at the culprit lesion in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: Preinterventional IVUS images of 73 patients with AMI were identified. The remodeling index (RI) was defined as the ratio of the external elastic membrane (EEM) areas at the culprit lesion to the EEM areas at the proximal reference site. Expansive remodeling was defined as an RI > 1.05; CR, as an RI < 0.95. In patients with AMI, 40 patients (55%) showed ER on IVUS, whereas CR was observed in 18 patients (25%). Patients with ER were significantly older than those with CR (P < .005). The frequency of the presence of calcifications was higher in patients with ER than in those with CR (P < .0005). In patients with AMI with ER, soft plaque with small calcium was the most frequent (58%). Multivariate analysis revealed that age and the presence of calcifications remained as independent predictors of ER. CONCLUSIONS: These findings suggest that ER relates to old age and calcification, and CR may contribute to early plaque progression than ER in patients with AMI.

Age Factors↗
PubMed2006

Method analysis for optimal continuous imaging using intravascular optical coherence tomography.

OBJECTIVES: Optical coherence tomography(OCT)is a high-resolution imaging method that can clearly visualize vessels through the displacement of blood with flushing agents. Continuous imaging methods have not been established. This study investigated optimal methods for continuous OCT imaging. METHODS: Thirty-four arteries with stent implantation (24 peripheral and 10 coronary arteries)in 14 pigs were examined using OCT with a motorized pullback device. Two imaging methods (flush alone by liquid substance and flush with occlusion) were compared. Adequate image acquisition was defined as the entire circumferential intimal layer being detectable within continuous segments. To investigate factors that could influence image quality, stented regions were divided into 4-5 mm segments. RESULTS: The flush with occlusion method provided better OCT images compared to flush alone (flush with occlusion: 60.9%, flush alone: 8.7%, p = 0.0002). Using the flush with occlusion method, the rate of adequate image acquisition was 64.4% and visualization of > 75% intimal circumference was 83.5%. Intravascular ultrasound could detect all stented regions. Segmental analyses found more adequate images were detected in smaller vessels (adequate segment: 3.8 +/- 0.4 mm, inadequate segment: 4.2 +/- 0.8 mm, p < 0.0001) or with centered image wire position (adequate segment: center 35%, inadequate segment: center 14%, p = 0.003). In addition, side branches did not affect image quality. CONCLUSIONS: To acquire continuous OCT images, the flush with occlusion method was more effective compared to flush alone. Moreover, image quality is affected by vessel size and imaging wire position. These results suggest that optimized OCT imaging can provide continuous vessel detection.

Animals↗
PubMed2005

Heterogeneity of neointimal distribution of in-stent restenosis in patients with diabetes mellitus.

Diabetes mellitus is an independent predictor of restenosis after percutaneous coronary intervention. The pattern of restenosis after bare metal stent implantation in diabetic patients was examined with 3-dimensional intravascular ultrasound analysis. Lumen and stent were manually traced at every 0.5-mm interval in stented segments. Using Simpson's method, stent, luminal, and neointimal (stent minus lumen) volumes were calculated and average area was calculated as volume data divided by length. To measure the cross-sectional and longitudinal severities of luminal encroachment by the neointima, percent neointimal area (neointimal area divided by stent area) and neointimal hyperplasia 50 (IH50) (defined as percent stent length with percent neointimal area >50%) were calculated. In 278 patients (68 with diabetes and 210 without diabetes), there was a significantly higher percentage of maximal percent neointimal area with significantly longer percent stent length that was severely encroached by the neointima in diabetic patients. Diabetic patients showed a more heterogenous pattern of the neointima after bare metal stenting, resulting in longer high-grade obstruction segments. This may have important implications for stent design and pharmacokinetic properties of next-generation drug-eluting technology for this complex patient subset.

Aged↗
PubMed2005

Effect of lumen narrowing within coronary stents on proximal and distal vessel segments following bare metal stent implantation.

Adjacent reference vessel response to smaller lumens at stented segments was examined with 3-dimensional intravascular ultrasound analysis. In 128 patients after bare metal stent implantation, minimal lumen area (MLA) within the stent and average lumen area at distal/proximal adjacent reference segments (5 mm) were obtained at baseline and follow-up. In the smaller in-stent MLA group (MLA <3 mm2), lumen area decreased significantly at the distal edge compared with the larger in-stent MLA group (MLA > or =3 mm2), although no significant difference was seen at the proximal edge. In-stent lumen patency may influence vascular responses at adjacent reference segments after bare metal stent implantation.

Coronary Disease↗
PubMed2004

Impact of HMG-CoA reductase inhibitors for non-treated coronary segments.

BACKGROUND: HMG-CoA reductase inhibitors (statin) have been reported to decrease coronary artery events in several angiographic studies. However, the mechanism by which statin achieve this is still unclear. The purpose of this study was to identify the effect of statin on coronary plaque using serial intravascular ultrasound analysis. METHODS AND RESULTS: In this study, 48 patients with 48 lesions were divided into the prescribed group (statin group, n = 22) or the non-prescribed group (control group, n = 26) after successful coronary artery stenting. IVUS images were obtained at consecutive 5 mm segments, 5 mm from the proximal stent edge, immediately after stenting and at 6 months follow up. External elastic membrane volume (EEMV), lumen volume (LV) and plaque volume (PV) were measured using Simpson's method. The control group revealed no significant serial change in EEMV, PV, and LV during 6 months. On the other hand, the statin group revealed significant reductions of PV (35.5 +/- 12.7 mm3 vs 30.9 +/- 15.6 mm3, p = 0.001), resulting in increase of LV (47.7 +/- 19.8 mm3 vs 52.5 +/- 22.2 mm3, p = 0.003) without EEMV change (82.8 +/- 21.8 mm3 vs 83.9 +/- 25.7 mm3, p = NS). Although percent EEMV and percent LV changes showed no differences between the two groups, a larger percent PV change was observed in the statin group compared to the control group (control; 5.8 +/- 20.3% vs statin; -20.4 +/- 21.8%, p = 0.02). CONCLUSION: The results of this study suggest that statin administration for 6 months reduces coronary plaque without positive vessel remodeling.

Aged↗
PubMed2004

The relationship between left ventricular geometric remodeling and cardiac function in essential hypertension.

BACKGROUND: Abnormal left ventricular (LV) diastolic relaxation is an early sign of hypertensive heart disease. Whether diastolic dysfunction differs between LV geometric patterns remains controversial. METHODS AND RESULTS: We examined 220 hypertensive patients by echocardiography to assess the relationship between diastolic function and LV geometric pattern. We identified four LV geometric patterns: normal geometry, concentric remodeling, concentric hypertrophy, and eccentric hypertrophy. Diastolic function was evaluated by the E/A ratio, E wave deceleration time (Dct), and isovolumic relaxation time (IRT). The E/A ratio was below one and Dct was prolonged in each group. The duration of IRT in the concentric and eccentric hypertrophy groups was significantly longer than that in normal geometry and concentric remodeling groups (p < 0.05). CONCLUSIONS: Hypertensive patients may be possible to have diastolic dysfunction, regardless of the differences in their structural geometry. The degree of impairment of cardiac diastolic function differed between hypertensive patients with different LV geometric patterns.

Aged↗
PubMed2004

The impact of IVUS guided bare metal stent implantation for non-small vessel.

UNLABELLED: Previous studies have shown larger target vessel or greater stent area contribute to reduced restenosis rate. Thus, intravascular ultrasound (IVUS)-guided bare metal stent (BMS) implantation for selected lesions might achieve drug-eluting stent-like outcomes. The aim was to examine the long-term outcomes of BMS using IVUS-guided optimization. METHODS: Consecutive 103 coronary artery lesions suitable for IVUS were enrolled. Using IVUS, final stent balloon size selected was 90 percent of media-to-media diameter at the lesion or distal reference. The balloon size was listed as follows: group A (3.0-3.5 mm, n = 15), group B (3.5-3.75 mm, n = 64), and group C (3.75-4.5 mm, n = 24). RESULTS: At post-intervention, average stent area increased by the balloon size (A: 7.2 +/- 1.4 mm2, B: 8.9 +/- 1.5 mm2, and C: 12.1 +/- 2.0 mm2, respectively p < 0.001). At 6 month follow up, the average lumen area increased by balloon size (A: 4.1 +/- 1.7 mm2, B: 5.7 +/- 1.2 mm2, and C: 8.1 +/- 2.0 mm2, respectively p < 0.001). Accordingly, group B and C revealed lower restenosis, compared to group A (A: 46.7%, B: 10.9%, C: 8.3%, A vs B: p = 0.001; C vs A: p = 0.015). Moreover, target lesion revascularization was less in group B and C than group A (A 26.6%, B 3.1%, C 0%, A vs B: p = 0.011; C vs A: p = 0.017). CONCLUSIONS: For non-small vessels, IVUS-guided BMS implantation showed less restenosis and target lesion revascularization compared to small vessels, mainly due to larger initial gain. These study results suggest that IVUS-guided optimal BMS implantation for selected lesions might result in favorable long-term outcomes similar to those seen using drug-eluting stents. For a decade, coronary stenting has become a standard therapy for coronary artery disease due to favorable long-term outcomes and simple treatment procedure. Furthermore, for the last two years, drug-eluting stents (DES), releasing antiproliferative agents from bare metal backbone, revealed the restenosis rates less than half of those seen using conventional bare metal stents (BMS). While target lesions especially suitable for DES continue to be identified, earlier BMS studies showed that larger target vessel or greater stent area contributed to less restenosis. Thus, optimal IVUS-guided BMS implantation for selected lesions might achieve DES-like long-term outcomes. This study was designed to examine the long-term outcomes of BMS with intravascular ultrasound (IVUS)-guided optimization, using coronary angiography and IVUS data.

Aged↗
PubMed2003

Late incomplete stent apposition and focal vessel expansion after bare metal stenting.

Late incomplete stent apposition was observed in 2.4% of the 412 stented segments studied by serial intravascular ultrasound analyses. Most of these phenomena and all late vessel expansions with incomplete stent apposition developed in vessels in which lesions were treated by atherectomy before stenting, suggesting a potential association between mechanical injury from debulking and these phenomena.

Aged↗
PubMed2003

Impact of deep vessel wall injury on acute response and remodeling of coronary artery segments after cutting balloon angioplasty.

Deep vessel wall injury is believed to affect vessel dimension following coronary intervention. The cutting balloon is designed to treat coronary artery stenoses with dilatation and surgical incisions, thereby reducing excess vessel injury. This study examines the effect of deep vessel wall injury on acute and late coronary arterial response after cutting balloon angioplasty. Serial volumetric intravascular ultrasound (IVUS) analyses were performed in 63 lesions treated with cutting balloon angioplasty alone. Before intervention, the longitudinal range of the lesion segment that included the smallest lumen area (LA) was determined as LA <4 mm(2) and/or LA stenosis >60%. The exact corresponding site at postintervention and follow-up was aligned using peri- and intravascular landmarks. Average vessel area (VA), plaque area (PA), and LA were measured. Lesion segments were categorized as with or without deep vessel wall injury, which was defined as the presence of plaque/vessel wall fracture extending to the sonolucent (medial) layer. Before intervention, the lesion vessel size of deep injury group was smaller than that of the nondeep injury group (p <0.05 for average VA and PA), whereas average lesion LA, lesion length, and reference vessel size did not differ. Immediately after cutting balloon angioplasty, the deep injury group showed a significant increase in VA (p <0.0001) and a lesser decrease in PA (p <0.01) compared with the nondeep injury group. During follow-up, the increase of VA tended to be greater in the deep injury group than in the nondeep injury group (p = 0.06), whereas the change of PA did not differ. Consequently, LA decrease was less in the deep injury group than in the nondeep injury group (p <0.05). From these results, it is suggested that deep vessel wall injury tends to occur in lesions with relatively small size and such lesions show favorable vessel response after cutting balloon angioplasty.

Aged↗
PubMed2003

Taxol-based eluting stents from theory to human validation: clinical and intravascular ultrasound observations.

Treatment with antiproliferative drugs via coated stents appears to be a promising approach to both mechanically remodel target lesions and biologically reduce neointimal hyperplasia. Drug-eluting stents can maximize local drug effects and minimize the potential for systemic toxic effects. The purpose of this review is to describe the effects of a lipophilic microtubular inhibitor, paclitaxel, a strong antiproliferative agent under clinical investigation, and to define the vascular response to taxol-based eluting stents by intravascular ultrasound.

Angiogenesis Inhibitors↗
PubMed2002

7-hexanoyltaxol-eluting stent for prevention of neointimal growth: an intravascular ultrasound analysis from the Study to COmpare REstenosis rate between QueST and QuaDS-QP2 (SCORE).

BACKGROUND: Inhibition of neointimal tissue growth has been demonstrated in preliminary human feasibility studies with a stent-based polymer sleeve delivering 7-hexanoyltaxol. The Study to COmpare REstenosis rate between QueST and QuaDS-QP2 (SCORE) trial is a human, randomized, multicenter trial comparing 7-hexanoyltaxol (QP2)-eluting stents (qDES) with bare metal stents (BMS) in the treatment of de novo coronary lesions. The purpose of this substudy was to evaluate the acute expansion property and long-term neointimal responses of qDES compared with BMS as assessed by intravascular ultrasound (IVUS). METHODS AND RESULTS: A total of 122 (qDES 66, BMS 56) patients were enrolled into the IVUS substudy. All IVUS images (immediately after the procedure and at 6-month follow-up) were analyzed at an independent core laboratory in a blind manner. At baseline, qDES achieved stent expansion similar to BMS. At follow-up, qDES showed reduced neointimal growth by 70% at the tightest cross section and by 68% over the stented segment (P<0.0001 for both), resulting in a significantly larger lumen in qDES than in BMS. Unlike intracoronary brachytherapy, there was no evidence of negative edge effects, unhealed dissections, or late stent-vessel wall malapposition over the stented and adjacent references segments in either group. CONCLUSIONS: Detailed IVUS analysis revealed that qDES had comparable acute mechanical and superior long-term biological effects to BMS. Although the long-term benefits and limitations of this technology require further investigation, the reduction in neointimal thickenings demonstrated that local delivery of 7-hexanoyltaxol through polymer sleeves augments conventional mechanical treatment of atherosclerotic disease.

Blood Vessel Prosthesis Implantation↗
PubMed2002

New catheter-based technology for the treatment of restenosis.

Catheter-based vascular interventions have been in development worldwide for several decades, leading to remarkable progress in device technology. Mechanical interventional devices, such as angioplasty balloons, atherectomy devices, and stents, were invented and have contributed greatly to the treatment of atherosclerotic vascular stenosis. However, mechanical approaches do not effectively prevent subsequent intimal growth. Recently, several biological approaches, including radiation therapy and drug-eluting stents, have shown striking inhibition of intimal growth. These significant results are likely to change the treatment strategy in the field of interventional cardiology. Furthermore, additional catheter-based technologies for vascular interventions are presently being evaluated. These latest technologies designed to prevent intimal proliferation include intravascular sonotherapy, cryotherapy, photoangioplasty, and soft X ray. To date, intravascular sonotherapy has proven its efficacy in animal studies and safety in human studies. Cryotherapy, the application of cold thermal energy during angioplasty, enhances the acute effects of conventional dilation while decreasing the likelihood of restenosis. Photoangioplasty has a unique property based on its selective mechanism of action to treat atheromatous plaque. Soft X ray systems provide convenient device handling and well-controlled radiation dose. Some of these technologies may play an important role in vascular interventions in the near future.

Animals↗