Biomedical subjects

Masaharu Okada

Publications and source records attributed to Masaharu Okada.

11 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

Mast cell tryptase in mast cell granules enhances MCP-1 and interleukin-8 production in human endothelial cells.

OBJECTIVE: Recent studies have highlighted the pathogenetic importance of chronic inflammation in cardiovascular disorders such as congestive heart failure and atherosclerosis. Mast cells release a wide variety of immune mediators that may initiate inflammatory responses, whereas endothelial cells (ECs) play a prominent role in the pathogenesis of cardiovascular diseases by secreting cytokines. The purpose of this study was to clarify the role of mast cells as an activator of ECs. METHODS AND RESULTS: ECs harvested from human umbilical cord veins were stimulated with mast cell granules (MCGs) prepared from sonicated human leukemic mast cells. The supernatants and total RNA from cells were collected. Levels of interleukin (IL)-1beta, tumor necrosis factor-alpha, and granulocyte colony-stimulating factor remained unchanged up to 24 hours. In contrast, levels of monocyte chemoattractant protein-1 (MCP-1) and IL-8 increased significantly within 6 hours. Northern blot analysis revealed an increase in MCP-1 and IL-8 mRNA expression in MCG-treated ECs. Induction of these chemokines was attenuated by antitryptase neutralizing antibody. Furthermore, MCP-1 and IL-8 were induced in ECs by incubation with human mast cell tryptase, but not with chymase. CONCLUSIONS: These results indicate that the production of MCP-1 and IL-8 in ECs was induced by MCG and amplified by tryptase.

Cells, Cultured↗

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

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

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

Evidence for a role of mast cells in the evolution to congestive heart failure.

Mast cells are believed to be involved in the pathophysiology of heart failure, but their precise role in the process is unknown. This study examined the role of mast cells in the progression of heart failure, using mast cell-deficient (WBB6F1-W/W(v)) mice and their congenic controls (wild-type [WT] mice). Systolic pressure overload was produced by banding of the abdominal aorta, and cardiac function was monitored over 15 wk. At 4 wk after aortic constriction, cardiac hypertrophy with preserved left ventricular performance (compensated hypertrophy) was observed in both W/W(v) and WT mice. Thereafter, left ventricular performance gradually decreased in WT mice, and pulmonary congestion became apparent at 15 wk (decompensated hypertrophy). In contrast, decompensation of cardiac function did not occur in W/W(v) mice; left ventricular performance was preserved throughout, and pulmonary congestion was not observed. Perivascular fibrosis and upregulation of mast cell chymase were all less apparent in W/W(v) mice. Treatment with tranilast, a mast cell-stabilizing agent, also prevented the evolution from compensated hypertrophy to heart failure. These observations suggest that mast cells play a critical role in the progression of heart failure. Stabilization of mast cells may represent a new approach in the management of heart failure.

Animals↗

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

Circulating hepatocyte growth factor as a diagnostic marker of thrombus formation in patients with cerebral infarction.

Circulating levels of hepatocyte growth factor (HGF) are increased in the early stage of an acute myocardial infarction because of arterial thrombosis. The purpose of this study was to use a new sensitive enzyme-linked immunosorbent assay to investigate whether circulating HGF is increased in patients with cerebral infarction. Circulating HGF was measured in 32 patients with cerebral infarction on admission to hospital and on days 2, 3, 7 and 14 after the onset of symptoms. Serum HGF levels exceeded the mean value +2SD (329pg/ml) measured in controls in 10 of 20 patients (50%) within 6 h after onset and in 15 of 32 patients (47%) within 24 h. Plasma D-dimer was increased in more than half of the patients with elevated HGF values. HGF levels in 16 patients who were measured serially were persistently increased throughout the study period. The results suggests that circulating HGF is a reliable early marker of cerebral infarction, and that this new sensitive HGF assay may be useful for diagnosing cerebral thrombosis.

Aged↗

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↗