Biomedical subjects

Michael Collins

Publications and source records attributed to Michael Collins.

At least 19 recordsLinked to original sources

PubMed2006

Volumetric intravascular ultrasound assessment of neointimal hyperplasia and nonuniform stent strut distribution in sirolimus-eluting stent restenosis.

The neointimal hyperplasia (IH) distribution pattern of in-stent restenotic lesions after sirolimus-eluting stent (SES) implantation has not been well described. We identified 48 in-stent restenotic lesions (41 patients) after SES implantation and performed volumetric intravascular ultrasound analyses. Lumen area, stent area, and IH area at the minimal lumen area site were 2.7 +/- 1.0, 5.4 +/- 1.9, and 2.7 +/- 1.4 mm(2), respectively. IH area at the minimal lumen site was larger in the group with a stent area > or =5.0 mm(2) than the group with a stent area <5.0 mm(2) (3.7 +/- 1.3 vs 1.9 +/- 0.8 mm(2), p <0.001). There were fewer visualized stent struts in lesions with a minimum stent area > or =5.0 mm(2) at the minimum lumen site compared with those with a stent area <5.0 mm(2) (0.69 +/- 0.25 vs 0.83 +/- 0.16, p = 0.04). When we compared lesions in patients with diabetes mellitus with patients without diabetes, minimum lumen areas, percent IH at minimal lumen area, percent IH, and neointima-free stent length were identical. In conclusion, (1) lesions without SES underexpansion at the minimum lumen site had more IH and greater nonuniform stent strut distribution compared with restenotic SESs that were underexpanded, and (2) the IH response did not appear to be more aggressive in patients with diabetes mellitus than in those without diabetes mellitus.

Aged↗

PubMed2006

Outcome after acute incomplete sirolimus-eluting stent apposition as assessed by serial intravascular ultrasound.

We investigated the fate of postprocedural incomplete stent apposition (ISA) after sirolimus-eluting stent (SES) implantation by evaluating long-term intravascular ultrasound findings in 168 consecutive patients (182 de novo lesions). Postprocedural ISA was defined as > or = 1 stent strut that was clearly separated from the vessel wall with evidence of blood speckle behind the strut without overlapping a side branch. After SES implantation, there were 61 ISA sites in 46 stents in 31 patients (23 at the proximal edge, 7 at the distal edge, and 31 within the stent body). There were no clinical, procedural, or intravascular ultrasound measurement differences between patients and lesions with versus without ISA. At follow-up, 15 acute ISA sites (25%) in 11 patients completely resolved and 40 sites (75%) in 20 patients persisted, although 32 of 46 persisting ISA sites (70%) decreased. There was a greater decrease in effective lumen area and a greater increase in peristent plaque area in the complete-resolution group than in the persistent-ISA group. No lesion developed stent thrombosis or in-stent restenosis (angiographic diameter stenosis > 50%). Six acute ISA sites were also associated with new, late acquired ISA, only 1 of which resulted in aneurysm formation. Although most ISAs after SES implantation do not resolve completely, the incidence of restenosis or thrombosis is not affected.

Acute Disease↗

PubMed2006

Treatment of coronary artery perforations complicating percutaneous coronary intervention with a polytetrafluoroethylene-covered stent graft.

Coronary artery perforation is a rare, but dreaded, complication of percutaneous coronary intervention. Conventional treatment, including reversal of anticoagulation and prolonged balloon inflation, is associated with a high incidence of death, Q-wave myocardial infarction, and emergency coronary bypass surgery. Although a number of case reports have demonstrated the feasibility of sealing coronary perforations with synthetic material-covered stent grafts, the efficacy of this treatment has not been reported in a large, multicenter series. We used a retrospective international registry to examine the outcomes of the polytetrafluoroethylene-coated JOSTENT coronary stent graft (CSG) in 41 cases of coronary perforations. Perforations were relatively severe: 16.7% Ellis grade 1, 54.2% grade 2, and 29.1% grade 3. Of the 41 patients, > 1/3 (n = 14) experienced life-threatening complications before stent graft implantation, including pericardial tamponade (12.2%), cardiogenic shock (9.8%), and cardiac arrest (2.4%). A total of 52 CSGs were used to treat the 41 perforations (mean 1.3 per lesion). All CSGs were placed successfully, with 92.9% of the perforations sealed completely and 7.1% partially. One patient developed abrupt vessel closure after CSG deployment, resulting in an overall procedure success rate of 96.4%. No in-hospital Q-wave myocardial infarctions, emergency coronary bypass surgeries, or deaths resulted. The CSG may be a reliable and highly effective treatment option for sealing coronary perforations complicating percutaneous coronary interventions.

Aged↗

PubMed2006

Predictors of vinorelbine pharmacokinetics and pharmacodynamics in patients with cancer.

PURPOSE: Marked interindividual variation in drug disposition and toxicity pose an ongoing challenge to chemotherapy dosage individualization. The aim of this study was to evaluate pretreatment clinical features, genotype and functional indicators of drug clearance as predictors of vinorelbine clearance, and myelotoxicity that could inform dosage optimization. PATIENTS AND METHODS: Forty-one patients with cancer received a 60 mg intravenous dose of vinorelbine. Pretreatment routine body size measurements and blood tests were performed. Midazolam clearance and hepatic technetium labeled sestamibi (99mTc-MIBI) clearance were used to investigate CYP3A and ABCB1 (MDR1, P-glycoprotein) phenotype respectively and selected single nucleotide polymorphisms in CYP3A and ABCB1 were documented. A limited blood sampling strategy was employed and vinorelbine concentrations were determined by high-performance liquid chromatography. Posterior Bayesian estimates of vinorelbine clearance were obtained for each patient using population pharmacokinetic modeling. Myelotoxicity was estimated from the fractional survival of neutrophils post-treatment. RESULTS: There was 4.3-fold variation in vinorelbine clearance across the cohort. In a multivariable analysis, pretreatment estimated creatinine clearance (P < .01) and hepatic (99m)Tc-MIBI clearance (P = .01) were independent predictors of vinorelbine clearance. Fractional survival of neutrophils ranged from 1.3% to 100% and was significantly correlated with vinorelbine clearance (P < .01). Body-surface area was the only pretreatment predictor of fractional survival of neutrophils independent of vinorelbine clearance (P = .02). CONCLUSION: Specific indicators of drug clearance provide predictive information about vinorelbine pharmacokinetics, and body-surface area, probably reflecting normal bone marrow reserve, provides an additional pharmacodynamic indicator. Use of a fixed dose of vinorelbine with modifications guided by pretreatment measures is worthy of prospective evaluation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

Intravascular ultrasonic differences between aorto-ostial and shaft narrowing in saphenous veins used as aortocoronary bypass grafts.

Previous studies have reported differences in interventional complication rates that depend on saphenous vein graft (SVG) lesion location. However, little is known about morphologic differences between lesions in different SVG locations. We evaluated preintervention intravascular ultrasound (IVUS) images of 75 de novo SVG lesions (aorto-ostial, n = 15; shaft, n = 60) in 63 patients. IVUS data were measured at the minimal lumen area and at 2 proximal and 2 distal references. Positive remodeling was defined as a lesion site SVG area that was larger than the average of the 2 distal references. Shaft lesions more often contained soft plaque (60.0% vs 26.7%, p = 0.02). Minimal lumen areas were identical (4.5 +/- 2.9 vs 4.3 +/- 1.5 mm2, p = 0.3); however, plaque burden at the minimal lumen area was greater in shaft locations (79.3 +/- 9.4% vs 72.1 +/- 9.2%, p = 0.01). The frequency of positive remodeling in shaft versus aorto-ostial lesions was 70.2% versus 26.7% (p = 0.002). SVG shaft lesions have more soft plaque and larger plaque burdens and undergo positive remodeling more frequently than SVG aorto-ostial lesions. These IVUS differences may account for some of the location-specific differences in interventional complications.

Aged↗

PubMed2006

A prospective registry to evaluate sirolimus-eluting stents implanted at coronary bifurcation lesions using the "crush technique".

The "crush technique" has been proposed as an alternative approach to treat bifurcation lesions because of its predictability and high procedural success rate. However, few data are available regarding its safety and long-term efficacy. We report the long-term clinical outcomes of patients with coronary bifurcation lesions treated with sirolimus-eluting stents using the crush technique. From April 2003 to May 2004, 120 patients with coronary bifurcation lesions were treated with sirolimus-eluting stents using the crush technique. Six months of clinical follow-up was completed in 95.8% of patients. Mean patient age was 64 years; 36% had diabetes mellitus, and the left anterior descending artery/diagonal was the most frequent bifurcation location (69%). Final kissing balloon inflation was performed in 87.5% of patients. Compared with the main vessel, side branch lesions were shorter, with a smaller reference diameter and final in-stent minimum lumen diameter. Procedural success was achieved in 97.5%. At 30 days of follow-up, 1 patient had died of noncardiac causes and 2 patients (1.7%) had subacute stent thrombosis. At 6 months of follow-up, target lesion revascularization was required in 13 patients (11.3%), all of whom had focal restenosis predominantly at the side branch ostium. In conclusion, the crush technique with final kissing balloon inflation can be safely used by experienced operators to treat highly complex bifurcation lesions with sirolimus-eluting stents. The safety profile of this technique is similar to that of other bifurcation stenting techniques reported thus far. Nonetheless, despite the excellent patency rates of the main vessel, the need for revascularization at the ostium of the side branch was not fully eliminated.

Angioplasty, Balloon, Coronary↗

PubMed2006

IkappaB kinase-2-independent and -dependent inflammation in airway disease models: relevance of IKK-2 inhibition to the clinic.

Nuclear factor kappaB (NF-kappaB) is a transcription factor believed to be central in the expression of numerous inflammatory genes and the pathogenesis of many respiratory diseases. We have previously demonstrated increased NF-kappaB pathway activation in a steroid-sensitive animal model of lipopolysaccharide (LPS)-driven airway inflammation. It is noteworthy that this phenomenon was not observed in a steroid-insensitive model of elastase-induced inflammation in the rat. The aim of this study was to gather further evidence to suggest that these similar profiles of neutrophilic inflammation can be NF-kappaB-dependent or -independent by determining the impact of an IkappaB kinase-2 (IKK-2) inhibitor, 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1). In the LPS model, TPCA-1 blocked the increase in NF-kappaB DNA binding, a marker of NF-kappaB pathway activation. This inhibition was associated with a reduction in inflammatory mediator release [tumor necrosis factor alpha (TNFalpha)/interleukin-1beta (IL-1beta)/matrix metalloproteinase-9 (MMP-9)] and lung inflammatory cell burden (neutrophilia/eosinophilia). These data were paralleled with a steroid and in human cell based assays. In the elastase-driven inflammation model, in which our group has previously failed to measure an increase in NF-kappaB DNA binding, neither TPCA-1 nor the steroid, affected mediator release (IL-1beta/MMP-9) or cellular burden (neutrophilia/lymphomononuclear cells). This is the first study to examine the effect of an IKK-2 inhibitor in well validated models that mimic aspects of the inflammatory lesion evident in diseases such as COPD. In conclusion, we have demonstrated that animal models with similar profiles of airway inflammation can be IKK-2 inhibitor/steroid-sensitive or -insensitive. If both profiles of inflammation exist in the clinic, then this finding is extremely exciting and may lead to greater understanding of disease pathology and the discovery of novel anti-inflammatory targets.

Amides↗

PubMed2006

The Prestige crisis: operational oceanography applied to oil recovery, by the Basque fishing fleet.

On 19th November 2002, the oil tanker Prestige (containing 77,000 tonnes of heavy fuel no. 2 (M100)) sank in 3500 m of water, off the coast of northwestern Spain. Intermittent discharge of oil from the stricken tanker, combined with large-scale sea surface dispersion, created a tracking and recovery problem. Initially, conventional oil recovery approaches were adopted, close to the wreck. With time and distance from the source, the oil dispersed dramatically and became less viscous. Consequently, a unique monitoring, prediction and data dissemination system was established, based upon the principles of 'operational oceanography'; this utilised in situ tracked buoys and numerical (spill trajectory) modelling outputs, in combination with remote sensing (satellite sensors and visual observation). Overall, wind effects on the surface waters were found to be the most important mechanism controlling the smaller oil slick movements. The recovery operation involved up to 180 fishing boats, 9-30 m in length. Such labour-intensive recovery of the oil (21,000 tonnes, representing an unprecedented ratio of 6.6 tonnes at sea, per tonne recovered on land) continued over a 10 month period. The overall recovery at sea, by the fishing vessels, represented 63% of the total oil recovered at sea; this compares to only 37% recovered by specialised 'counter- pollution' vessels.

Atlantic Ocean↗

PubMed2006

Transcatheter aortic valve replacement in patients with critical aortic stenosis: rationale, device descriptions, early clinical experiences, and perspectives.

The development of lesser invasive transcatheter techniques for aortic valve replacement (AVR) to treat high surgical risk patients with severe aortic stenosis (AS) has engendered controversy among traditional cardiovascular therapists. Presently, there are two catheter-based treatment systems (the Cribier-Edwards Aortic Bioprosthesis and the CoreValve Revalving System) utilizing either a balloon-expandable or a self-expanding stent (or cage) platform which unfolds a pericardial tissue valve within the displaced diseased aortic valve. After ex vivo durability testing and animal studies, several clinical registries with these transcatheter AVR systems in almost 300 patients worldwide have demonstrated the following: (1) good acute hemodynamic performance with reduction in mean aortic valve gradients to <10 mm Hg; (2) frequent para-valvular regurgitation, which has improved with self-expanding devices and the use of larger (26 mm) valve sizes; (3) acceptable periprocedural (30-day) mortality (<10%) with the newest generation devices and improved operator techniques. Enlightened interdisciplinary treatment teams incorporating surgeons, interventionalists, and medical therapists as well as rigorously conducted randomized clinical trials will be required to determine if these innovative transcatheter AVR approaches will represent a viable therapy for high-risk patients with severe AS in the future.

Aortic Valve Insufficiency↗

PubMed2006

Chemical profiling of heroin recovered from the North Korean merchant vessel Pong Su.

Heroin samples, seized from the North Korean merchant vessel Pong Su in Australian waters, were analyzed to determine geographic origin. Duplicate samples were analyzed by the National Measurement Institute's Australian Forensic Drug Laboratory and the United States Drug Enforcement Administration's Special Testing and Research Laboratory. Alkaloid ratios were determined by both liquid chromatography-diode array detection (LC-DAD) and capillary electrophoresis-diode array detection (CE-DAD) techniques. Acid/neutral manufacturing by-products were determined by solvent extraction followed by gas chromatography-mass spectrometry (GC-MS). Solvents, trapped in the heroin particles during manufacture, were detected by both static headspace GC-MS and purge and trap GC-MS. The alkaloid ratios obtained were consistent with heroin of a Southeast Asian (SEA) origin and principal component analysis of the alkaloid results demonstrated the presence of at least four subgroupings within the seizure. The solvent analysis detected diethyl ether and ethyl acetate, solvents typically seen in SEA heroin. However, the acid/neutral analysis revealed compounds not normally seen in heroin of a SEA origin. Furthermore, sterol-like molecules, always detected in the acid/neutral analysis of SEA heroin, were absent from the Pong Su samples. The Pong Su heroin, although similar to SEA heroin, has sufficient differences to classify it as having an unknown origin at the time of this writing.

Journal Article↗

PubMed2006

Stable isotope analyses of heroin seized from the merchant vessel Pong Su.

A new type of heroin HCl seized in Australia was examined by stable isotope analysis. The final origin/process classification of these samples by chromatographic signature profiles of the impurity/manufacturing by-products was previously determined to be "unknown" by two independent national laboratories. Various drug enforcement authorities speculated that the heroin might be from a new region or new illicit process due to the unusual chromatographic impurity profiles that were present. Samples from 20 different kilogram packages were examined for isotopic content to determine if the samples fit isotopic patterns of known origins or if they were unique to any known origins. Authentic specimens from Southeast Asian (N=59), Southwest Asia (N=37), South America (N=104), and Mexico (N=21) we concomitantly examined for comparison purposes. Both continuous flow elemental analysis-isotope ratio mass spectrometry and gas chromatography-isotope ratio mass spectrometry techniques were utilized. Heroin samples were also converted to morphine, without apparent isotopic fractionation, utilizing methanolic HCl for gas chromatography-isotope ratio mass spectrometry. The Pong Su samples were found to be isotopically and isotopically/alkaloidally distinct from the known origin/process classifications of Southwest Asian, Southeast Asian, South American, and Mexican.

Journal Article↗

PubMed2006

Whole-genome plasticity among Mycobacterium avium subspecies: insights from comparative genomic hybridizations.

Infection with Mycobacterium avium subsp. paratuberculosis causes Johne's disease in cattle and is also implicated in cases of Crohn's disease in humans. Another closely related strain, M. avium subsp. avium, is a health problem for immunocompromised patients. To understand the molecular pathogenesis of M. avium subspecies, we analyzed the genome contents of isolates collected from humans and domesticated or wildlife animals. Comparative genomic hybridizations indicated distinct lineages for each subspecies where the closest genomic relatedness existed between M. avium subsp. paratuberculosis isolates collected from human and clinical cow samples. Genomic islands (n = 24) comprising 846 kb were present in the reference M. avium subsp. avium strain but absent from 95% of M. avium subsp. paratuberculosis isolates. Additional analysis identified a group of 18 M. avium subsp. paratuberculosis-associated islands comprising 240 kb that were absent from most of the M. avium subsp. avium isolates. Sequence analysis of DNA regions flanking the genomic islands identified three large inversions in addition to several small inversions that could play a role in regulation of gene expression. Analysis of genes encoded in the genomic islands reveals factors that are probably important for various mechanisms of virulence. Overall, M. avium subsp. avium isolates displayed a higher level of genomic diversity than M. avium subsp. paratuberculosis isolates. Among M. avium subsp. paratuberculosis isolates, those from wildlife animals displayed the highest level of genomic rearrangements that were not observed in other isolates. The presented findings will affect the future design of diagnostics and vaccines for Johne's and Crohn's diseases and provide a model for genomic analysis of closely related bacteria.

Animals↗

PubMed2006

A multicenter, randomized, dose-finding study of gamma intracoronary radiation therapy to inhibit recurrent restenosis after stenting.

OBJECTIVES: The objective of this double-blind, randomized study was to determine the safety and efficacy of intracoronary radiation therapy (ICRT) with a dose of 17 Gray (Gy) compared to the currently recommended dose prescription of 14 Gy for the treatment of in-stent restenosis within bare metal stents. BACKGROUND: While gamma ICRT for in-stent restenosis has been proven efficacious, the optimal dose is unknown, and radiation failure due to recurrent neointimal hyperplasia remains a significant clinical problem for some patients. A higher radiation dose may improve outcomes, but may potentially increase adverse events. METHODS: Following coronary intervention, 336 patients with in-stent restenosis were randomly assigned to receive ICRT with either 14 Gy or 17 Gy at 2 mm from an 192-iridium source. RESULTS: At 8-month follow up, fewer patients in the 17 Gy group underwent target lesion revascularization (TLR = 15.2% versus 27.2%; p = 0.01), target vessel revascularization (21.3% versus 33.1%; p = 0.02), or reached the composite endpoint of death, myocardial infarction, thrombosis, or TLR (17.1% versus 28.4%; p = 0.02). There were no differences in late thrombosis or mortality between treatment groups. There was a strong trend toward reduced in-lesion late loss (0.36 +/- 0.63 mm vs. 0.51 +/- 0.64 mm; p = 0.09) and a significantly lower rate of binary restenosis (23.9% versus 38.1%; p = 0.031) in the high dose group. CONCLUSIONS: Gamma ICRT with 17 Gy is safe and, compared to 14 Gy, reduces recurrent stenosis and clinical events at 8-month follow up. An increase in the currently recommended gamma radiation dose prescription from 14 Gy to 17 Gy should be strongly considered.

Aged↗

PubMed2005

Impact of coronary culprit lesion calcium in patients undergoing paclitaxel-eluting stent implantation (a TAXUS-IV sub study).

Randomized clinical trials have shown that paclitaxel-eluting stents significantly reduce restenosis after percutaneous coronary intervention. The impact of lesion calcification on the efficacy of paclitaxel-eluting stents is unknown. In the TAXUS-IV trial, 1,314 patients who underwent percutaneous coronary intervention were randomly assigned to a bare-metal or paclitaxel-eluting stent. By core laboratory analysis, 247 lesions (19%) were moderately or severely calcified. At the 9-month angiographic follow-up examination, the paclitaxel-eluting stent had significantly reduced the amount of late loss compared with the control stent (0.26 +/- 0.56 vs 0.51 +/- 0.48 mm, p = 0.015) within the analysis segment in the calcific lesions. The analysis segment restenosis rate was similar in patients with calcified and noncalcified lesions after paclitaxel-eluting stent implantation (7.5% vs 8.0%, respectively; p = 1.0). The rate of ischemia-driven target lesion revascularization (TLR) at 1 year was reduced by 56% in patients with calcified lesions (11.9% vs 5.1%, p = 0.09) and by 75% in noncalcified lesions (15.7% vs 4.3%, p <0.0001). By interaction testing, the efficacy of the paclitaxel-eluting stent in reducing TLR at 1 year was similar in the calcified and noncalcified lesions (p = 0.30). Moreover, by multivariate analysis, implantation of the paclitaxel-eluting stent was a powerful independent predictor of freedom from TLR, with similar hazard ratios for efficacy in calcified and noncalcified lesions (0.30 and 0.26, respectively). In conclusion, implantation of paclitaxel-eluting stents in patients with de novo coronary lesions significantly reduced restenosis in patients with and without calcified lesions.

Angioplasty, Balloon, Coronary↗

PubMed2005

Bifurcation coronary lesions treated with the "crush" technique: an intravascular ultrasound analysis.

OBJECTIVES: We report intravascular ultrasound (IVUS) findings after crush-stenting of bifurcation lesions. BACKGROUND: Preliminary results with the crush-stent technique are encouraging; however, isolated reports suggest that restenosis at the side branch (SB) ostium continues to be a problem. METHODS: Forty patients with bifurcation lesions underwent crush-stenting with the sirolimus-eluting stent. Postintervention IVUS was performed in both branches in 25 lesions and only the main vessel (MV) in 15 lesions; IVUS analysis included five distinct locations: MV proximal stent, crush area, distal stent, SB ostium, and SB distal stent. RESULTS: Overall, the MV minimum stent area was larger than the SB (6.7 +/- 1.7 mm2 vs. 4.4 +/- 1.4 mm2, p < 0.0001, respectively). When only the MV was considered, the minimum stent area was found in the crush area (rather than the proximal or MV distal stent) in 56%. When both the MV and the SB were considered, the minimum stent area was found at the SB ostium in 68%. The MV minimum stent area measured <4 mm2 in 8% of lesions and <5 mm2 in 20%. For the SB, a minimum stent area <4 mm2 was found in 44%, and a minimum stent area <5 mm2 in 76%, typically at the ostium. "Incomplete crushing"--incomplete apposition of SB or MV stent struts against the MV wall proximal to the carina--was seen in >60% of non-left main lesions. CONCLUSIONS: In the majority of bifurcation lesions treated with the crush technique, the smallest minimum stent area appeared at the SB ostium. This may contribute to a higher restenosis rate at this location.

Angioplasty, Balloon, Coronary↗

PubMed2005

Intravascular ultrasound study of patterns of calcium in ruptured coronary plaques.

Coronary calcium is intimately associated with coronary atherosclerotic plaque development, although it is controversial as to whether coronary calcium is associated with plaque instability. We analyzed 101 IVUS-detected ruptured plaques and compared them with 101 computer-matched control plaques without evidence of plaque rupture. The arc of calcium was measured every 0.5 mm within 10-mm-long segments that spanned the minimum lumen cross-sectional area, and the number and length of calcium deposits were assessed. Ruptured plaques had a significantly larger number of individual calcium deposits than control plaques (3.5 +/- 1.7 vs 1.8 +/- 1.1, p <0.001). However, the arc of the largest calcium deposit was smaller and the length of the largest calcium deposit in each plaque was shorter in ruptured plaques compared with control plaques (67.3 degrees +/- 41.4 degrees vs 114.9 degrees +/- 77.4 degrees , p <0.001, and 1.6 +/- 1.3 vs 4.0 +/- 2.7 mm, p <0.001, respectively). There was no difference in the number of superficial calcium deposits between the 2 groups, although ruptured plaques had significantly smaller arcs of superficial calcium compared with control plaques (56.2 degrees +/- 35.5 degrees vs 95.8 degrees +/- 65.2 degrees , p <0.001). Conversely, the number of deep calcium deposits was significantly larger in ruptured plaques than in control plaques (1.8 +/- 1.4 vs 0.3 +/- 0.6, p <0.001), although the arc of deep calcium was similar in the 2 groups. Ruptured plaques had quantitatively less calcium, especially superficial calcium, but a larger number of small calcium deposits, especially deep calcium deposits. In conclusion, ruptured plaques are associated with a larger number of calcium deposits within an arc of <90 degrees , a larger number of deep calcium deposits, and a remodeling index.

Aged↗

PubMed2005

Intravascular ultrasonic assessment of stent diameters derived from manufacturer's compliance charts.

We used intravascular ultrasound (IVUS) to assess the accuracy of manufacturers' stent balloon compliance charts. Many interventional cardiologists rely on manufacturers' compliance charts to select stent size and optimize stent diameters according to inflation pressures during percutaneous procedures. We randomly selected 212 patients who had de novo coronary lesions that had been treated with a single, bare metal, > or =3.0-mm stent (Bx velocity, NIR, TETRA/PENTA, S660/S670/S7) under IVUS guidance. Cases of stent overlap and postdilatation with another balloon were excluded. Predicted stent diameters were derived from each manufacturer's compliance charts, and stent size and final maximal deployment pressures were derived from each physician's report. IVUS-measured minimum stent diameters (range 1.4 to 4.0 mm, mean 2.79 +/- 0.48) were smaller than predicted diameters (range 3.1 to 4.57 mm, mean 3.79 +/- 0.44). The ratio of IVUS to predicted diameters ranged from 44% to 97% (mean 74 +/- 10%). This finding was common to all 3 stent sizes: 74 +/- 12% for 3.0 mm, 73 +/- 9% for 3.5 mm, and 74 +/- 9% for 4.0-mm stents (p = 0.9). This finding was also common to all 4 stent manufacturers, 72 +/- 8% for Boston Scientific, 76 +/- 11% for Guidant, 73 +/- 9% for Cordis, and 74 +/- 11% for Medtronic (p = 0.13), and to different stent lengths. Only 3.8% of the stents achieved 90% of the predicted minimum stent diameters, and only 24.6% achieved 80% of the predicted minimum stent diameters. In conclusion, in human coronary arteries, minimal stent diameter measured by IVUS is significantly smaller than that predicted by in vitro compliance charts. These differences are independent of stent manufacturer, length, diameter, and deployment pressure.

Aged↗

PubMed2005

Stent underexpansion and residual reference segment stenosis are related to stent thrombosis after sirolimus-eluting stent implantation: an intravascular ultrasound study.

OBJECTIVES: We sought to determine the predictors of stent thrombosis after sirolimus-eluting stent (SES) implantation. BACKGROUND: A number of cases of stent thrombosis have been reported after commercial release of the SES in the "real world," such that the U.S. Food and Drug Administration issued a warning. METHODS: Fifteen patients who developed stent thrombosis after successful SES implantation were analyzed and compared with 45 matched control patients who had no evidence of stent thrombosis. RESULTS: Minimum stent cross-sectional area (MSA) (4.3 +/- 1.6 mm(2) vs. 6.2 +/- 1.9 mm(2), p < 0.001) and stent expansion (0.65 +/- 0.18 vs. 0.85 +/- 0.14, p < 0.001) were significantly smaller in the stent thrombosis group than in the matched control patients. There was no significant difference in the rate of SES malapposition between the groups. However, the presence of a significant residual reference segment stenosis was more common in the stent thrombosis group compared with the matched control group (67% vs. 9%, p < 0.001). Independent predictors of stent thrombosis were stent underexpansion (p = 0.03) and a significant residual reference segment stenosis (p = 0.02). CONCLUSIONS: Stent underexpansion and residual reference segment stenosis are associated with stent thrombosis after successful SES implantation.

Aged↗