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Biomedical subjects

William Wijns

Publications and source records attributed to William Wijns.

16 recordsLinked to original sources
PubMed2003

Intracoronary and intravenous adenosine 5'-triphosphate, adenosine, papaverine, and contrast medium to assess fractional flow reserve in humans.

BACKGROUND: Inducing both maximal and steady-state coronary hyperemia is of clinical importance to take full advantage of fractional flow reserve measurements. The present study compares different dosages and routes of administration of adenosine 5'-triphosphate (ATP), adenosine, contrast medium, and papaverine regarding their potential to achieve both maximal and steady-state hyperemia. METHODS AND RESULTS: In 21 patients with an isolated coronary stenosis, coronary vasodilation was induced successively by papaverine (20 mg intracoronary), adenosine (20 and 40 microg intracoronary), ATP (20 and 40 microg intracoronary), iohexol (6 mL intracoronary), adenosine or ATP through an antecubital vein (140 and 180 microg x kg(-1) x min(-1)), or adenosine or ATP through a femoral vein (140 and 180 microg x kg(-1) x min(-1)). Because vessel dimensions did not change, the ratio of distal coronary pressure (Pd) to aortic pressure (Pa) was used as an index of myocardial resistance. Pd/Pa was 0.77+/-0.21 at rest and decreased to 0.61+/-0.21 after papaverine. Pd/Pa decreased to a similar level with all other vasodilators, except with contrast medium (0.68+/-0.21; P<0.01 versus papaverine). Steady-state hyperemia could only be obtained by intracoronary papaverine and by intravenous ATP or adenosine. In another 23 patients, an intravenous infusion of ATP was varied from 0 to 280 microg x kg(-1) x min(-1). At doses >140 microg x kg(-1) x min(-1), there was neither a further decrease in Pd/Pa ratio nor a further increase in coronary flow velocities. CONCLUSIONS: Provided sufficient dosages are used, ATP, adenosine, and papaverine (but not contrast medium) induce maximal hyperemia and are therefore suitable to assess fractional flow reserve. Only intracoronary papaverine and intravenous ATP or adenosine induce steady-state hyperemia enabling a pressure pullback maneuver that is useful in assessing diffuse coronary atherosclerosis.

Adenosine↗
PubMed2003

Effect of angiotensin-converting enzyme inhibition on restenosis after coronary stenting.

The Plasma level of angiotensin-converting enzyme (ACE) has been identified as a major risk factor for restenosis after coronary stent implantation in selected patients; ACE inhibition may therefore contribute to prevent its occurrence. The effect of oral ACE inhibition at conventional doses was analyzed retrospectively in a series of 897 patients with ischemia who received >or=1 coronary stent on 998 lesions and underwent angiographic follow-up; no exclusion criteria were introduced in this analysis. The restenosis rate in 282 patients (31.4%) taking ACE inhibitors was 36.6% compared with 22.9% in 615 non-ACE-inhibited patients (p = 0.00001, odds ratio [OR] 1.94, 95% confidence interval [CI] 1.45 to 2.59), and the late loss in minimum lumen diameter was 1.25 +/- 0.8 versus 0.96 +/- 0.8 mm, respectively (p = 0.0001). During univariate analysis, a negative effect of the drug on restenosis was observed in all subgroups of patients (i.e., hypertensives, diabetics, women, and patients with previous myocardial infarction). Similar effects were observed independently of the ACE gene insertion/deletion polymorphism. During multivariate analysis, ACE inhibition was confirmed as an independent risk factor for restenosis (OR 1.84, 95% CI 1.35 to 2.51, p = 0.0001). Other predictors were the implantation of multiple stents (OR 2.41, 95% CI 1.60 to 3.64, p <0.0001), diabetes (OR 2.34, 95% CI 1.61 to 3.41, p <0.0001), and vessel reference diameter before angioplasty (OR 0.51, 95% CI 0.38 to 0.69, p <0.0001). Although unexplained and apparently contradictory, our data suggest that the use of conventional oral doses of ACE inhibitors in a "real-world" population who underwent coronary stent implantation increases the incidence of in-stent restenosis. Such a finding does not negate the known clinical benefits of ACE inhibitors, but it may deserve attention when a patient treated with ACE inhibitors becomes a candidate for stent implantation.

Analysis of Variance↗
PubMed2003

Direct stenting.

Stents have ameliorated the outcome of percutaneous coronary interventions. Improved design, profile and flexibility of the currently available stents now permit to deliver the stent without pre-dilatation. In western European countries, stent implantation now occurs in up to 80% of all percutaneous revascularization procedures. In selected cases the safety and feasibility of direct stenting over conventional balloon-predilatation stenting has been demonstrated, in association with slightly superior outcome. This likely results from reduced vessel wall damage-dissections are sealed at the moment they are created-and distal embolization is reduced. In addition, a significant reduction in terms of costs and duration of procedures was demonstrated, while restenosis rate is not reduced with direct stenting.

Angioplasty, Balloon, Coronary↗
PubMed2002

Angiographic analysis of the angioplasty versus rotational atherectomy for the treatment of diffuse in-stent restenosis trial (ARTIST).

Patients with diffuse in-stent restenoses (ISRs) are at high risk for recurrent restenosis after percutaneous transluminal balloon angioplasty (PTCA). Percutaneous transluminal rotational ablation (PTCR) has proved effective in removing neointimal burden in ISRs. This study compares the acute and long-term results of PTCA and PTCR for the treatment of diffuse ISR in a randomized, multicenter investigation. The primary end point was the comparison of the minimum luminal diameter (MLD) between both groups at 6-month follow-up. Patients with symptomatic, diffuse, or high-grade ISRs were included; 146 patients were randomized to PTCA and 152 patients to PTCR. Diameter stenosis was reduced from 80 +/- 12% to 29 +/- 10% and from 80 +/- 11% to 28 +/- 12%, respectively, and MLD increased from 0.55 +/- 0.3 to 1.9 +/- 0.3 mm in the PTCA group and from 0.54 +/- 0.3 mm to 1.9 +/- 0.4 mm in the PTCR group. Spasm in the treated vessel and an intermittent slow flow phenomenon occurred more often after rotational ablation (17.7% vs 8.6%, p = 0.001; 5.3% vs 0%, p = 0.007). Minimum stenosis diameter at 6-month follow-up was smaller in the PTCR group than in the PTCA group (1.0 +/- 0.6 vs 1.2 +/- 0.6 mm, p = 0.008) and the restenosis rate was higher (64.9% vs 51.2%, p = 0.027). Procedural factors did not influence long-term outcome. In the PTCR group, the restenosis rate increased with decreasing vessel size, whereas this was not seen in the PTCA group. The lesion length and the baseline diameter stenosis were found to be predictive of restenosis with both treatment strategies; however, a residual diameter stenosis of <30% predicted absence of a restenosis only in the PTCR group. Thus, PTCA and PTCR of diffuse ISRs yield comparable acute angiographic results. The recurrence of a restenosis is higher after PTCR than after PTCA.

Aged↗
PubMed2002

Intravascular ultrasound findings in the multicenter, randomized, double-blind RAVEL (RAndomized study with the sirolimus-eluting VElocity balloon-expandable stent in the treatment of patients with de novo native coronary artery Lesions) trial.

BACKGROUND: The goal of this intravascular ultrasound investigation was to provide a more detailed morphological analysis of the local biological effects of the implantation of a sirolimus-eluting stent compared with an uncoated stent. METHODS AND RESULTS: In the RAVEL trial, 238 patients with single de novo lesions were randomized to receive either an 18-mm sirolimus-eluting stent (Bx VELOCITY stent, Cordis) or an uncoated stent (Bx VELOCITY stent). In a subset of 95 patients (sirolimus-eluting stent=48, uncoated stent=47), motorized intravascular ultrasound pullback (0.5 mm/s) was performed at a 6-month follow-up. Stent volumes, total vessel volumes, and plaque-behind-stent volumes were comparable. However, the difference in neointimal hyperplasia (2+/-5 versus 37+/-28 mm3) and percent of volume obstruction (1+/-3% versus 29+/-20%) at 6 months between the 2 groups was highly significant (P<0.001), emphasizing the nearly complete abolition of the proliferative process inside the drug-eluting stent. Analysis of the proximal and distal edge volumes showed no significant difference between the 2 groups in external elastic membrane or lumen and plaque volume at the proximal and distal edges. There was also no evidence of intrastent thrombosis or persisting dissection at the stent edges. Although there was a higher incidence of incomplete stent apposition in the sirolimus group compared with the uncoated stent group (P<0.05), it was not associated with any adverse clinical events at 1 year. CONCLUSIONS: Sirolimus-eluting stents are effective in preventing neointimal hyperplasia without creating edge effect and without affecting the plaque burden behind the struts.

Blood Vessel Prosthesis Implantation↗
PubMed2002

Accuracy of PET in predicting functional recovery after revascularisation in patients with chronic ischaemic dysfunction: head-to-head comparison between blood flow, glucose utilisation and water-perfusable tissue fraction.

Accurate prediction of improvement in left ventricular ejection fraction (LVEF) after revascularisation is critical in the therapeutic decision-making process in patients with chronic ischaemic dysfunction. Positron emission tomography (PET) allows non-invasive evaluation of myocardial blood flow (MBF), metabolic rate of glucose (MRG, absolute and relative) and the water-perfusable tissue fraction (PTF). Each of these indices has been proposed for the prediction of functional recovery. Their relative merits, however, are unknown, because a direct head-to-head comparison of their predictive accuracy in the same patients has not been performed. In this study, MBF, MRG (absolute and relative) and PTF were evaluated in 34 patients with severe ischaemic LV dysfunction (LVEF 32%+/-9%). MBF and PTF were determined by oxygen-15 labelled water PET, and MRG (absolute and relative) was determined by fluorine-18 fluorodeoxyglucose (FDG) PET during hyperinsulinaemic euglycaemic clamp. LVEF was measured by radionuclide ventriculography before and 4-6 months after surgery. Sensitivities of MBF, PTF, absolute MRG and relative MRG in predicting improvement in LVEF were 80%, 80%, 90% and 100%, respectively. Their specificities were 54%, 67%, 71% and 71%, respectively. The lowest specificity was obtained for MBF, an intermediate specificity was obtained for PTF and the highest specificities were obtained with FDG PET using absolute and relative MRG. It is concluded that metabolic imaging is superior to perfusion-based indexes for assessment of the potential for functional recovery after revascularisation.

Adult↗
PubMed2002

Haptoglobin phenotype and the risk of restenosis after coronary artery stent implantation.

We recently demonstrated that an allelic polymorphism in the haptoglobin gene is a major determinant of susceptibility to a number of vascular disorders. We set out to determine if haptoglobin phenotype was predictive of the development of restenosis in a consecutive series of patients, all of whom underwent stent implantation followed by repeat angiography with quantitative coronary angiography analysis 6 months later. This study included 214 consecutive patients undergoing stent implantation for de novo lesions between 1998 and 1999 in Aalst, Belgium. All underwent follow-up quantitative coronary angiography analysis 6 months after the procedure. The haptoglobin phenotype was determined by electrophoresis. No significant differences were found between patients segregated by phenotype with respect to clinical, procedural, and angiographic factors previously suggested to influence the development of restenosis. None of the diabetic patients homozygous for the haptoglobin 1 allele developed restenosis compared with a >50% restenosis rate for diabetic patients with at least 1 haptoglobin 2 allele (p <0.02). In all patients (diabetic and nondiabetic), we observed a trend toward a lower incidence of restenosis in patients homozygous for the 1 allele (21% vs 33%, p <0.09). Moreover, we found a graded risk relation to the number of haptoglobin 2 alleles. The risk of developing restenosis was greater in subjects with 2 haptoglobin 2 alleles (36%) than in those with 1 haptoglobin 2 allele (31%) or no haptoglobin 2 alleles (21%). Thus, knowledge of the haptoglobin phenotype may be useful in assessing and utilizing new therapies that attempt to reduce restenosis, and may have important implications for the risk stratification algorithm used in managing diabetic patients with coronary artery disease.

Aged↗
PubMed2002

The effect of completeness of revascularization on event-free survival at one year in the ARTS trial.

OBJECTIVES: We sought to assess the relationship between completeness of revascularization and adverse events at one year in the ARTS (Arterial Revascularization Therapies Study) trial. BACKGROUND: There is uncertainty to what extent degree of completeness of revascularization, using up-to-date techniques, influences medium-term outcome. METHODS: After consensus between surgeon and cardiologist regarding the potential for equivalence in the completeness of revascularization, 1,205 patients with multivessel disease were randomly assigned to either bypass surgery or stent implantation. All baseline and procedural angiograms and surgical case-record forms were centrally assessed for completeness of revascularization. RESULTS: Of 1,205 patients randomized, 1,172 underwent the assigned treatment. Complete data for review were available in 1,143 patients (97.5%). Complete revascularization was achieved in 84.1% of the surgically treated patients and 70.5% of the angioplasty patients (p < 0.001). After one year, the stented angioplasty patients with incomplete revascularization showed a significantly lower event-free survival than stented patients with complete revascularization (i.e., freedom from death, myocardial infarction, cerebrovascular accident and repeat revascularization) (69.4% vs. 76.6%; p < 0.05). This difference was due to a higher incidence of subsequent bypass procedures (10.0% vs. 2.0%; p < 0.05). Conversely, at one year, bypass surgery patients with incomplete revascularization showed only a marginally lower event-free survival rate than those with complete revascularization (87.8% vs. 89.9%). CONCLUSIONS: Complete revascularization was more frequently accomplished by bypass surgery than by stent implantation. One year after bypass, there was no significant difference in event-free survival between surgically treated patients with complete revascularization and those with incomplete revascularization, but patients randomized to stenting with incomplete revascularization had a greater need for subsequent bypass surgery.

Aged↗
PubMed2002

A randomized comparison of the value of additional stenting after optimal balloon angioplasty for long coronary lesions: final results of the additional value of NIR stents for treatment of long coronary lesions (ADVANCE) study.

OBJECTIVES: We sought to investigate the clinical benefit of additional stent implantation after achieving an optimal result of balloon angioplasty (BA) in long coronary lesions (>20 mm). BACKGROUND: Long coronary lesions are associated with increased early complications and late restenosis after BA. Stenting improves the early outcome, but stent restenosis is also related to both lesion length and stent length. METHODS: A total of 437 patients with a single native lesion 20 to 50 mm in length were included and underwent BA, using long balloons matched to lesion length and vessel diameter (balloon/artery ratio 1.1) to achieve a diameter stenosis (DS) <30% by on-line quantitative coronary angiography (QCA). "Bail-out stenting" was performed for flow-limiting dissections or >50% DS. Patients in whom an optimal BA result was achieved were randomized to additional stenting (using NIR stents) or no stenting. The primary end point was freedom from major adverse cardiac events (MACE) at nine months, and core laboratory QCA was performed on serial angiograms. RESULTS: Bailout stenting was necessary in 149 patients (34%) and was associated with a significantly increased risk of peri-procedural infarction (p < 0.02). Among the 288 randomized patients, the mean lesion length was 27+/-9 mm, and the vessel diameter was 2.78+/-0.52 mm. The procedural success rate was 90% for the 143 patients assigned to BA alone (control group), as compared with 93% in the 145 patients assigned to additional stenting (stent group), which resulted in a superior early minimal lumen diameter (0.54 mm, p < 0.001) and led to reduced angiographic restenosis (27% vs. 42%, p = 0.022). Freedom from MACE at nine months was 77% in both groups. CONCLUSIONS: A strategy of provisional stenting for long coronary lesions led to bailout stenting in one-third of patients, with a threefold increase in peri-procedural infarction. Additional stenting yielded a lower angiographic restenosis rate, but no reduction in MACE at nine months.

Aged↗
PubMed2002

Dose distributions for 90Y intravascular brachytherapy sources used with balloon catheters.

The dose distribution around an intravascular brachytherapy 90Y line source with centering balloon catheters was measured with a plastic scintillator, TLD and radiochromic film. The absolute dose rates measured with the three detectors in a solid water phantom at 1, 2 and 3 mm distance from the centering balloon surfaces are in agreement within 3.5%, when the detectors are calibrated with the same 90Sr/90Y source. The dose rates measured with the plastic scintillator in the solid water phantom are in agreement with those directly measured in water. The measured relative dose distributions can be reproduced by Monte Carlo calculations. Also, the influence of the balloon diameter on the dose rate can be reproduced by the calculations. The dose rate calibration routinely performed with the plastic scintillator was checked for fifty-one sources with a well chamber and with another dedicated dose rate checking device. These measurements show that the consistency of the calibration of these sources was better than 10%. In a previous paper absolute dose rates for five other 90Y sources measured with TLD and radiochromic film in a solid water phantom were compared with those obtained with the plastic scintillator in water [Piessens and Reynaert, "Verification of absolute dose rates for intravascular beta sources," Phys. Med. Biol. 45, 2219-2231 (2000)]. Differences of 25 to 41%, depending on the balloon diameter, were reported. In this paper we show the evidence for three main reasons for these previously observed discrepancies: an inconsistency between a detector calibration performed with a 6 MeV electron beam and with a calibrated 90Sr/90Y source from NIST (16%), inaccuracies of the measuring distances in the solid water phantom (maximum 7.5%) and a time instability of the plastic scintillator, probably due to radiation damage (6%).

Brachytherapy↗
PubMedDate not supplied

Geographical miss and restenosis during catheter-based intracoronary beta-radiation for de novo lesions.

OBJECTIVES: We sought to determine the impact of geographical miss (GM) on restenosis rates after intracoronary beta-radiation therapy for de novo lesions. BACKGROUND: GM is the situation in which injured vessel segments (VSs) are receiving low-dose radiation and is accounted for edge restenosis. Its impact on the overall restenosis rates remains to be determined. METHODS: We analyzed 330 patients (356 vessels) treated according to the Beta Radiation in Europe (BRIE) and the Dose Finding study protocols. Using quantitative coronary angiography (QCA), the effective irradiated segment (EIRS), its edges and the total VS were analysed. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis > 50% at follow-up. GM was determined by the simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated and surrounded by contrast, at the site of injury, in identical angiographic projections. RESULTS: In 20.5% of the vessels, GM was non-interpretable due to inadequate filming. GM occurred at 30.4% of the interpretable edges and 53% of the interpretable vessels that were analysed. Edge restenosis was significantly increased in the GM compared to non-GM edges (13.16% vs. 4.17%, respectively, P = .001), both in the proximal (P = .03) and the distal (P = .001) edges. GM associated with stent injury significantly increased edge restenosis (P = .006). GM related to balloon injury tended to be associated with increment in edge restenosis (P = .07). The restenosis in the EIRS was similar between vessels with and without GM (17.78% and 14.85%, respectively, P = .6). GM was associated with significant increment in the restenosis at the analyzed VS (31.85% vs. 21.48%, P = .05). CONCLUSIONS: GM is strongly associated with edges and restenosis in the analysed VS. GM does not increase restenosis in the EIRS.

Angioplasty, Balloon, Coronary↗