PubMed Health⌕ Search

Biomedical subjects

Hideo Tamai

Publications and source records attributed to Hideo Tamai.

18 recordsLinked to original sources
PubMed2006

Histopathological findings of new in-stent lesions developed beyond five years.

We analyzed 14 cases of new lesions inside implanted bare-metal stents. In every case, there was no angiographic restenosis within 3 years, but a new lesion was observed inside a stented segment at long-term follow-up (>5 years). Fourteen cases were evaluated: 9 with Wiktor stents, 2 with Palmaz-Schatz stents, and 3 with ACS Multilink stents. The interval from stent implantation to follow-up angiography was 63-147 months (89 +/- 23). Thirteen lesions were treated by percutaneous coronary intervention (PCI) and stenotic tissue was obtained by directional coronary atherectomy (DCA) in 10 cases. All retrieved samples were composed of newly developed atherosclerosis facing the healed neointimal layer, and four samples showed histopathological findings of acute coronary syndrome. Stent struts were retrieved in four cases and no inflammation was observed surrounding them. Qualitative and quantitative analysis of stent struts was performed in two cases that showed no metal corrosion. These findings suggest that new atherosclerotic progression occurred inside the implanted stent without peristrut inflammation.

Aged↗
PubMed2005

Serial angioscopic findings after successful intracoronary brachytherapy for in-stent restenosis.

The intracoronary changes that occur after brachytherapy for in-stent restenosis (ISR) have yet to be fully established. The purpose of this study in patients who had ISR was to examine the serial angioscopic changes in intracoronary lesions that occurred after brachytherapy. Forty-four patients who had ISR (49 lesions) underwent balloon angioplasty (n = 34) or directional atherectomy (n = 15), followed by intracoronary brachytherapy using a beta-emitting phosphorus-32 source wire. Angioscopic investigations were performed 3 and 9 months after brachytherapy. Uncovered stents were detected in 63.3% of lesions at 3 months. A significant decrease (p = 0.028) in this prevalence occurred over the next 6 months, with 36% of lesions having uncovered stents at 9 months. At 3 months, 33% of the lesions had visible erosion or ulceration and superficial thrombus. The prevalence of these characteristics was decreased at 9 months, although 17% of the lesions were still ulcerated or eroded at that time. Protruding thrombus was not observed in any lesion at 3 and 9 months. In conclusion, uncovered stents and intimal erosions or ulcerations were still present 9 months after brachytherapy in 36% and 17% of lesions, respectively. These results suggest that the healing process was not completed 9 months after brachytherapy in approximately 33% of lesions.

Aged↗
PubMed2005

The safety and efficacy of "pre-closure" utilizing the Closer suture-mediated vascular closure device for achievement of hemostasis in patients following coronary interventions: results of the second Perclose Accelerated Ambulation and Discharge (PARADISE II) Trial.

BACKGROUND: Suture-mediated closure devices have been developed to improve patient comfort and safety following percutaneous coronary interventions (PCI). The Perclose AcceleRated Ambulation and DISchargE (PARADISE) trial which we reported previously showed that the Prostar XL appears to be a safe and effective device to achieve hemostasis, improve time-to-ambulation and discharge post-PCI. The diameter of suture capture with the Closer 6 Fr suture-mediated closure device is larger than an 8 Fr hole. This study was performed to assess the pre-closure efficacy using the Closer device in terms of time-to-hemostasis, ambulation and discharge, as well as the incidence of peripheral vascular complications. METHODS: Between January and September 2001, 153 consecutive patients were enrolled in this study. In 97 patients, the Closer sutures were introduced prior to insertion of the 8 Fr sheath (pre-closure arm). In 56 patients, the sutures were tied at the conclusion of PCI upon sheath removal (standard arm). RESULTS: The Closer device was successfully placed on 152 of 153 attempts. The time-to-hemostasis, ambulation and discharge of the pre-closure arm patients seemed to be comparable to those of the standard arm and the PARADISE trial. No major complications were reported. CONCLUSION: The Closer seems to be as safe and effective as the Prostar XL device. The pre-closure technique is a safe means of achieving hemostasis post-PCI using large-sized sheaths without major complications.

Adult↗
PubMed2004

Frequency and time course of reocclusion and restenosis in coronary artery occlusions after balloon angioplasty versus Wiktor stent implantation: results from the Mayo-Japan Investigation for Chronic Total Occlusion (MAJIC) trial.

BACKGROUND: Compared with balloon angioplasty, stent implantation has been shown to reduce restenosis and reocclusion after treatment of chronic total coronary artery occlusions (CTOs). However, little is known about the time course of restenosis and reocclusion after the 2 procedures. The purpose of this study was to examine the frequency and time course of restenosis and reocclusion after treatment of CTOs with balloon angioplasty and Wiktor stent implantation. METHODS AND RESULTS: A total of 221 patients with successfully recanalized CTOs were randomly assigned to either treatment with a coil stent implantation (Wiktor stent, n = 110) or standard balloon angioplasty (n = 111). Repeat angiography was performed the day after treatment and at 6 months. Patients undergoing balloon angioplasty showed 29.8% restenosis and 1.1% reocclusion the following day versus 2% restenosis and no reocclusion in stent patients the following day. The cumulative reocclusion rate was significantly lower in the stent group than in the balloon group at 6 months (2.1% versus 9.3%, P <.05). As a result of the more frequent need of target vessel revascularization (49.5% in the balloon group and 30.6% in the stent group, P <.005) and earlier final follow-up angiography in the balloon group, the frequency of angiographic restenosis at 6 months was similar in both groups (57.3% in the stent group and 54.5% in the balloon group). CONCLUSIONS: The frequency and time course of reocclusion and restenosis after balloon angioplasty and stent placement differ within 24 hours of the procedure and remain different on angiography at 6 months.

Aged↗
PubMed2004

New tubular bioabsorbable knitted airway stent: feasibility assessment for delivery and deployment in a dog model.

PURPOSE: The aim of this study was to determine whether it is possible to deliver and deploy a new device, a poly-L-lactic acid (PLLA) tubular knitted airway stent, under bronchoscopic guidance in a dog model. DESCRIPTION: The delivery system consisted of a flexible balloon catheter (controlled radial expansion balloon dilator, M00558440, Boston Scientific Corporation, MA, USA) preloaded with a stent. A delivery catheter preloaded with a stent was advanced to a target point in the trachea under bronchoscopic guidance. Once the stent was positioned, the balloon was inflated for sixty seconds. The stent was in full contact with the tracheal wall upon deflation of the balloon. EVALUATION: The stents were successfully delivered into the tracheal lumen and successfully deployed in all dogs. CONCLUSIONS: This is the first study to prove the feasibility of delivering and deploying the PLLA stents in a dog model, using a balloon expansion technique. Further investigation with large numbers of subjects and long-term follow-up will be necessary to assess the utility of the bioabsorbable knitted tubular stent before clinical applications begin.

Absorbable Implants↗
PubMed2004

Predictors of improvement in left ventricular function after initially successful angioplasty of unprotected left main coronary artery stenoses.

BACKGROUND: Percutaneous coronary intervention (PCI) has been increasingly applied to unprotected left main coronary artery (LMCA) lesions, with varied procedural success and clinical outcomes. However, the effect of PCI on left ventricular performance is still unclear, and there are no clinical studies assessing factors that influence left ventricular ejection fraction (LVEF) in these cases. METHODS: Between April 1986 and August 2002, de novo PCI was performed for unprotected LMCA stenoses in 199 patients. Close clinical and angiographic follow-up were conducted after the procedure. RESULTS: One hundred eighty patients survived over six months and analysis of paired left ventriculography was possible in 175 patients. Improvement in LVEF was observed in the entire population (52.9 +/- 15.7% to 56.1 +/- 14.3%, p = 0.048). The LVEF change was 6.7 +/- 9.5% (p < 0.01) in group with baseline LVEF < or = 50% and 0.7 +/- 6.7 % (p = NS) in group with LVEF > 50%. There was significant intergroup difference (p < 0.001). Patients with baseline diameter stenosis > or = 60% had an improvement of 5.3 +/- 8.3% (p < 0.05) whereas those with stenosis < 60% had no improvement (2.0 +/- 8.4%, p = NS). CK-MB elevation > or = 3 times normal after PCI had a significant inverse association with improvement in LVEF (p < 0.05). Multivariate analysis revealed baseline LVEF < or = 50% was the only independent predictor of improvement in LVEF (standard estimate = 3.509, 95% CI: 2.164-4.854, p < 0.001). CONCLUSIONS: Successful PCI procedure is associated with significant improvement in LVEF, especially in patients with depressed left ventricular function.

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

Intravascular ultrasound-guided directional coronary atherectomy for unprotected left main coronary stenoses with distal bifurcation involvement.

Stent implantation in unprotected left main coronary artery (LMCA) bifurcation lesions may improve procedural and late clinical outcomes. However, concerns regarding stent-related complications, such as stent jail, subacute thrombosis, and in-stent restenosis remain. Optimal debulking by directional coronary atherectomy (DCA) with intravascular ultrasound (IVUS) guidance may be effective in this complex lesion subset, but this strategy has not yet been established. Our objective was to evaluate the safety and efficacy of IVUS-guided DCA for unprotected LMCA stenoses with distal bifurcation involvement. A total of 67 consecutive patients were included in this study and procedural success was achieved in all cases. Two cardiac deaths (2.9%) were noted and 3 patients (4.5%) underwent repeat angioplasty during hospitalization. There was no Q-wave myocardial infarction or emergency bypass surgery. Non-Q-wave myocardial infarction (creatine kinase-MB >3 times normal) occurred in 13.4% of patients. Stent implantation was necessary in 17 cases (25.4%) to achieve an optimal result. IVUS showed an improved lumen cross-sectional area and a low plaque burden in the LMCA after intervention. All-cause mortality, angiographic restenosis, and the target lesion revascularization rates at 6 months were 7.4%, 23.8%, and 20.0%, respectively. With IVUS guidance, aggressive DCA can be performed safely in unprotected LMCA bifurcation lesions, and optimal angiographic and IVUS results can be achieved with low residual plaque burden, which leads to a low restenosis rate. Optimal lesion debulking by DCA does not necessarily need adjunctive stenting in this specific anatomic subset.

Aged↗
PubMed2003

New technique for superior guiding catheter support during advancement of a balloon in coronary angioplasty: the anchor technique.

To get superior guiding catheter support, we tried a new method called the anchor technique. By inflating a balloon in a nontarget vessel and holding its shaft with backward force while advancing another balloon, the anchor effect for the guiding catheter could be obtained and it appeared to be helpful for a balloon or a stent to cross the target lesion.

Aged↗
PubMed2003

Biodegradable stents as a platform to drug loading.

Despite technical and mechanical improvement in coronary stents the incidence of restenosis caused by in-stent neointimal hyperplasia remains high. Oral administration of numerous pharmacological agents has failed to reduce restenosis after coronary stenting in humans, possibly owing to insufficient local drug concentration. Therefore, drug-eluting stents were developed as a vehicle for local drug administration. The authors developed a new drug-eluting polymer stent that is made of poly-l-lactic acid polymer mixed with tranilast, an anti-allergic drug that inhibits the migration and proliferation of vascular smooth muscle cells induced by platelet-derived growth factor and transforming growth factor->1. Polymer stents might be superior to polymer-coated metallic stents as local drug delivery stents in terms of biodegradation and the amount of loaded drug. Drug-mixed polymer stents can be loaded with a larger amount of drug than can drug-coated metallic stents because the polymer stent struts can contain the drug. Clinical application is required to assess the safety and efficacy of drug-eluting polymer stents against stent restenosis.

Absorbable Implants↗
PubMed2003

Lesion regression after percutaneous coronary intervention for unprotected left main trunk disease.

BACKGROUND: Although some studies have documented the six-month angiographic outcomes of percutaneous coronary intervention (PCI) with new devices for unprotected left main trunk disease (ULMTD), a long-term angiographic analysis is mandatory to evaluate the safety and effectiveness of this procedure. This study aims to assess a long-term (one year or more) angiographic analysis after PCI for this lesion. METHODS: PCI was performed for 225 ULMTD with de novo or restenotic lesions. There were 19 deaths and 12 repeat PCIs during the hospital stay. The remaining 194 lesions were followed, and 126 lesions showed no angiographic restenosis or target lesion revascularization within six months. Finally, long-term quantitative angiographic follow-up was completed in 78 lesions (mean 2.4 years, maximum 7.5 years after PCI). RESULTS: Minimal lumen diameter increased significantly from 2.46 +/- 0.59 mm to 2.72 +/- 0.65 mm (p < 0.0001) and percent diameter stenosis decreased significantly from 26 +/- 14% to 19 +/- 14% (p < 0.0001) between the six-month and the long-term follow-ups. No additional restenosis or new lesions were found at long-term follow-up, and significant lesion regression was ascertained in each procedure (directional coronary atherectomy, p < 0.005; ballooning, p < 0.005; stenting, p < 0.05). CONCLUSIONS: These findings support the safety and effectiveness of PCI for ULMTD during the long-term period.

Adult↗
PubMed2002

Comparison of the self-expanding Radius stent and the balloon-expandable Multilink stent for elective treatment of coronary stenoses: a serial analysis by intravascular ultrasound.

We compared the outcome of the self-expanding Radius stent and the balloon-expandable Multilink stent serially by angiography and intravascular ultrasound. Successful stent deployment was achieved in 66 lesions of 56 stable angina patients (34 lesions with Radius stents and 32 lesions with Multilink stents). At follow-up, there were no significant differences in minimal lumen diameter or percent diameter stenosis between the groups, nor in restenosis rates, although the Radius stent group rate was slightly lower (23.5% vs. 31.3%). In the Radius stent group, stent cross-sectional area (CSA) increased gradually after implantation until the 6-month follow-up (8.37 +/- 1.83 to 10.16 +/- 2.59 mm(2); n = 15), giving a larger CSA (P = 0.03) than the Multilink stent group, which decreased (9.00 +/- 2.05 to 8.27 +/- 2.15 mm(2); n = 17). The lumen CSA was also slightly larger (6.82 +/- 3.06 vs. 5.84 +/- 1.85 mm(2); P = 0.29) in the Radius stent group. These findings indicated that the Radius stent enlarged progressively after implantation, which might be useful for prevention of restenosis.

Aged↗
PubMed2002

The impact of tranilast on restenosis after coronary angioplasty: the Second Tranilast Restenosis Following Angioplasty Trial (TREAT-2).

BACKGROUND: The Tranilast Restenosis Following Angioplasty Trial showed that oral administration of 600 mg/day of tranilast for 3 months markedly reduced the restenosis rate after percutaneous transluminal coronary angioplasty (PTCA) for de novo lesions. METHODS: We conducted the second multicenter, randomized, double-blinded placebo-controlled trial. A total of 297 patients with 329 lesions were randomly assigned to treatment with tranilast or a placebo for 3 months after successful PTCA for both de novo and restenotic lesions. Angiographic follow-up examination was done at 3 months, and angiograms were interpreted with a quantitative approach. RESULTS: Two hundred thirty-nine lesions (72.6%) in 216 of the patients (72.7%) met the criteria and were included in the assessment of restenosis. Lesion restenosis was defined as a loss of 50% or more of the initial gain, and the restenosis rates were 18.8% in the tranilast group (n = 112) and 44.1% in the placebo group (n = 127; P =.00005). The restenosis rate, defined as a percent stenosis of > or = 50% at follow-up examination, was also significantly lower in the tranilast group (25.9% versus 41.9%; P =.012). The numbers of restenotic lesions were 38 (33.9% of 112) in the tranilast group and 30 (23.6% of 127) in the placebo group. In restenotic lesions, the lesion restenosis rate was significantly lower in the tranilast subgroup (18.4% versus 53.3% with the first restenosis criterion; P =.004). CONCLUSION: The oral administration of tranilast for 3 months markedly reduced the restenosis rate after PTCA, even in restenotic lesions.

Administration, Oral↗
PubMed2001

Biodegradable Polymeric Stents.

To overcome several problems of conventional metallic stents, there have been many attempts to manufacture stents made of biodegradable materials. Although some studies have noted various degrees of inflammatory responses after biodegradable stent implantation, stents made of poly-l-lactic acid (PLLA) showed high biocompatibility with minimal inflammatory response and neointimal formation in porcine coronary arteries. Therefore, PLLA materials are more likely to cover the specific need for human coronary arteries in terms of biodegradation period and scaffolding ability over 6 months. A clinical study of PLLA self-expanding stent implantation is underway in Japan. The initial and 6-month results are favorable and suggest the feasibility, safety, and efficacy of the PLLA biodegradable stent in humans. However, long-term follow-up with larger numbers of patients will be required to validate the long-term efficacy of PLLA stents.

Journal Article↗