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R Bonan

Publications and source records attributed to R Bonan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Reliability of mechanical and phased-array designs for serial intravascular ultrasound examinations--animal and clinical studies in stented and non-stented coronary arteries.

BACKGROUND: Both mechanical and multi-element intravascular ultrasound designs have potential advantages and limitations that may impact on their value for clinical and research purposes. Determination of the reproducibility of measurements is critical before a given system can be used in studies such as regression of atherosclerosis trials. METHODS: We performed serial intravascular ultrasound imaging with catheters using mechanical and phased-array designs in stented and non-stented coronary arteries in dogs and in patients. RESULTS: Both systems correlated well for areas (r > or = 0.90, p < 0.0001) and diameters (r > or = 0.84. p < 0.0001) in dogs and in patients. There was a slight difference between multi-element and mechanical designs for measurements of area (mean difference in dogs and in patients: -0.24 and 0.96 mm2, p < 0.055) and diameter (-0.08 and 0.16 mm, p < 0.0001). The reproducibility of the multi-element system for reanalysis of the same frames and for analysis of serial pullbacks was similar to the same measurements with the mechanical system (r > or = 0.96 for all measurements). The differences in absolute and relative variability between the mechanical and phased-array designs, both for reanalysis of same frames and serial pullbacks, were very small. CONCLUSIONS: Although multi-element and mechanical intravascular ultrasound designs are not strictly interchangeable, their similar reproducibility and the small differences in measurements demonstrate that both designs are acceptable alternatives for trials of regression of atherosclerosis. Determination of the variability for serial pullbacks of both designs was also important to assess the statistical power of such trials.

Animals↗
PubMed2000

Multicenter evaluation of the phosphorylcholine-coated biodivYsio stent in short de novo coronary lesions: The SOPHOS study.

AIMS: The BiodivYsio trade mark stent (Biocompatibles Ltd, Farnham, UK) is coated with a phosphorylcholine (PC)-containing copolymer to confer biocompatibility. The SOPHOS (Study Of PHosphorylcholine coating On Stents) study was designed to assess the safety and efficacy of this novel coronary stent and by indirect comparison to indicate equivalence with other formal stent studies. METHODS AND RESULTS: Patients with angina and a single short (#x2A7F;12 mm) de novo lesion in a native coronary artery of >/=2.75 mm diameter were included. A total of 425 patients were allocated in 24 centers. Clinical data were collected at one-, six- and nine-month follow-up. Angiography was performed before and after the stent implantation. In addition, in the first 200 patients (SOPHOS A) angiography was routinely performed at six months. The following 225 patients (SOPHOS B) were merely followed up clinically. The primary end-point of the study, the six-month MACE-rate (MACE = Major Adverse Cardiac Events) was 13.4% (two cardiac death; five Q-wave/nine non-Q-wave myocardial infarctions (MI); nine CABG and 32 target lesion revascularization (TLR), which is similar to the calculated 15% MACE-rate in comparable reference studies. Secondary end-points included among others restenosis at six months in the SOPHOS A population. The target vessel diameter was 2.98 +/- 0.48 mm. Minimal lumen diameter pre/post procedure and at follow-up was 1.00 +/- 0.32, 2.69 +/- 0.37, 1.91 +/- 0.71 mm, respectively. The binary restenosis rate (>/=50% diameter stenosis at follow-up) was 17.7%. CONCLUSION: The coronary BiodivYsio stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with stable or unstable angina pectoris. Clinical and angiographic results are in the statistical range of equivalence with comparable studies with other current stents.

Journal Article↗
PubMed1999

Value of exercise electrocardiography in the detection of restenosis after coronary angioplasty in patients with one-vessel disease.

Exercise treadmill testing (ETT) is considered an unreliable method for detection of restenosis after percutaneous transluminal coronary angioplasty (PTCA). The studies on which this belief is based have used quantitative coronary angiography (QCA) as a reference. The inherent limitations of angiography have been demonstrated by intravascular ultrasound (IVUS). To determine the value of ETT for detecting restenosis when IVUS criteria are used to define restenosis, we studied 29 patients with angiographically documented 1-vessel coronary disease (<35% stenosis in all nondilated segments) who underwent angioplasty. ETT was performed < or =2 weeks before follow-up angiography and IVUS imaging. Only patients without any abnormalities precluding an accurate reading of the ST segment during ETT were included. Restenosis was defined as a > or =50% diameter stenosis by QCA criteria and as a cross-sectional area narrowing of > or =75% by IVUS. The ETT was positive in 12 patients and restenosis was documented by QCA and IVUS in 38% and 48% of cases, respectively. Sensitivity, specificity, and positive and negative predictive values of ETT when QCA was used as a reference were 55%, 67%, 50%, and 71%, respectively. This corresponded to an accuracy of 62% when compared with QCA. Sensitivity, specificity, and positive and negative predictive values were 79%, 93%, 92%, and 82% when ETT was compared with IVUS, with an accuracy of 86% (p = 0.002). Thus, ETT is a reliable noninvasive method for detecting the presence of restenosis after PTCA in patients with 1-vessel coronary artery disease. The presence of > or =75% cross-sectional narrowing shown by IVUS is well correlated with > or =1-mm ST-segment depression at follow-up ETT after PTCA.

Aged↗
PubMed1999

Effects of intracoronary beta-radiation therapy after coronary angioplasty: an intravascular ultrasound study.

BACKGROUND: Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound. METHODS AND RESULTS: Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups. CONCLUSIONS: beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.

Adult↗
PubMed1998

Local administration of L-703,081 using a composite polymeric stent reduces platelet deposition in canine coronary arteries.

We compared the effect on platelet deposition of the glycoprotein IIb/IIIa receptor antagonist L-703,081, administered locally via a drug delivery stent, with that of a standard metal stent in a canine coronary model. There was a significant reduction in platelet deposition using the L-703,081-impregnated stent compared with the bare metal stent. This study demonstrates an alternative route of delivery of GPIIb/IIIa antagonists with potential advantages over systemic administration.

Animals↗
PubMed1998

Efficacy of beta radiation in prevention of post-angioplasty restenosis. An interim report from the beta energy restenosis trial.

UNLABELLED: Restenosis remains a major limitation of coronary angioplasty in spite of major advances in techniques and technology. Recent studies have demonstrated that ionizing radiation may limit the degree of this problem. Gamma radiation has been shown to be effective in reducing in stent restenosis in humans, and beta radiation following encouraging results in animals has been shown to be feasible in humans. The objective of this study was to assess the feasibility of a 5 F non-centered catheter to deliver beta radiation emitting seeds to the lesion site post angioplasty and its effect on restenosis. Following successful angioplasty, patients were randomized to treatment with 12, 14 or 16 Gy at the angioplasty site. This was delivered with a 5 F non-centered catheter. Twelve beta radiation emitting seeds (90Sr/Y) were delivered to an area 3 cm in length to cover the angioplasty site. Angiographic follow-up was performed at 6 months. Baseline and follow-up angiograms were performed by blinded investigators at a core laboratory. This interim report comprises the first 35 patients to complete 6-month angiographic follow-up. There were no major radiation incidents. Four patients had evidence of angiographic restenosis. The MLD (mm) and percent stenosis were 0.77 +/- 0.27/72.5 +/- 8.6 pre angioplasty, 2.08 +/- 0.4/25.7 +/- 9.8 post angioplasty and radiation and 2.05 +/- 0.59/25.7 +/- 19.8 at follow-up respectively. CONCLUSION: Beta radiation can be feasibly and safely delivered post coronary angioplasty with a very encouraging reduction of restenosis.

Adult↗
PubMed1998

Comparison of ionic and nonionic low osmolar contrast media in relation to thrombotic complications of angioplasty in patients with unstable angina.

BACKGROUND: Acute complications of percutaneous transluminal coronary angioplasty (PTCA) are more common in patients with unstable coronary syndromes. The objective of this study was to prospectively determine the differences between ionic and nonionic low osmolar contrast media (LOCM) on potential risk of acute complications, particularly abrupt vessel closure, in patients with unstable angina undergoing PTCA. METHODS: A total of 210 patients with 278 lesions were randomized to receive either ionic or nonionic LOCM during PTCA. Quantitative coronary angiographic measurements and assessment of filling defects were made by experienced observers who were blinded to the type of contrast media used. RESULTS: The baseline clinical and angiographic characteristics, the immediate postangioplasty results, and clinical outcome were similar in both groups. Subacute recoil, defined as the difference between minimal luminal diameter (in millimeters) at 0 and 15 minutes after angioplasty, was significantly greater in patients receiving nonionic LOCM (0.17 +/- 0.36 mm vs 0.07 +/- 0.18 mm, p = 0.004). A filling defect abnormality attributable to dissection, thrombus, or a combination of the two was noted in similar proportions of the two groups. Although nonsignificant, more thrombus was noted in the nonionic group (21 of 129 vs 15 of 141, p = NS). The abrupt vessel closure rate was similar in the two groups and was only 1.9% in the first 24 hours. However, 17 (8.3%) patients had a repeat PTCA at 15 minutes (9 ionic vs 8 nonionic). CONCLUSION: In patients with unstable angina the choice of ionic or nonionic LOCM does not appear to significantly affect the clinical outcome of PTCA.

Adult↗
PubMed1998

Reduced pulmonary clearance of endothelin-1 in pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension (PHT) is associated with increased endothelin-1 (ET-1) levels that correlate with the severity of the disease. The pulmonary circulation is an important site for ET-1 metabolism and may modulate plasma ET-1 through an increase in production, a reduction in removal, or a combination of both. We measured and compared pulmonary metabolism of circulating ET-1 in controls and in patients with PHT. METHODS AND RESULTS: The indicator-dilution technique was combined with measurements of ET-1 levels to quantify pulmonary metabolism of ET-1 in controls (n = 13) and in patients with PHT (n = 17). ET-1 levels doubled in PHT (p < 0.05) and, although there was no difference between aortic and pulmonary artery levels in controls (0.68+/-0.09 and 0.61+/-0.08 pg/ml, respectively, p = 0.22), they tended to be higher in PHT (1.23+/-0.26 vs 1.07+/-0.19 pg/ml, p = 0.08). Pulmonary extraction of tracer iodine-125-ET-1 was reduced from 47%+/-2.0% in the controls to 34%+/-3.6% in PHT (p = 0.005) and inversely correlated with the severity of pulmonary hypertension (r = -0.524, p = 0.03). Consequently, circulating ET-1 clearance was reduced by PHT from 1424+/-77 ml/min to 892+/-119 ml/min (p < 0.001). Pulmonary production of circulating ET-1 (in picograms per minute) was not different but the quantity of ET-1 that survives passage through the lungs was increased by PHT (1860+/-359 pg/min vs 992+/-152 pg/min, p = 0.037). CONCLUSION: PHT is associated with a reduced pulmonary clearance of ET-1 that contributes to the increase in circulating levels.

Aorta, Thoracic↗
PubMed1998

Incidence, outcome and prediction of early clinical events following percutaneous transluminal coronary angioplasty. A comparison between treatment with reviparin and unfractionated heparin/placebo (results of a substudy of the REDUCE trial).

BACKGROUND: Unfractionated heparin and its low molecular weight fragments possess antithrombotic properties, properties that are routinely exploited in coronary angioplasty (PTCA). OBJECTIVES: In the setting of the REDUCE trial, a randomized, double-blind, multicentre trial, the occurrence of acute or early clinical events was compared in patients treated with either unfractionated heparin/placebo or low molecular weight heparin (reviparin). METHODS AND RESULTS: Six hundred and twelve patients with native coronary artery obstructions randomized between unfractionated heparin/placebo and reviparin, were analysed. Baseline characteristics were similar in both groups. Using the intention-to-treat analysis, major acute or early events (myocardial infarction, re-PTCA, bypass surgery, death) occurred in 42 patients (7%), 29 in the control group and 13 in the treatment group (P=0.027). In order to develop a predictive model for the risk of early events following coronary balloon angioplasty, clinical as well as pre-PTCA and procedural characteristics were analysed. Thrombi at the treated lesion site (P=0.02), dissection (P<0.001), lesion type B2 and C according to the NHLBI classification (P<0.001), diameter stenosis >50% post-PTCA (P<0.001), and length of stenosis >20mm (P=0.005) were significantly associated with the occurrence of acute events. By multiple logistic regression analysis, in which these variables and the treatment regimen were entered, dissection (P=0.042), diameter stenosis >50% (P<0.028) and lesion type B2 and C (P=0.017) were found to be independently predictive of early adverse events. Bleeding complications were similar in the two treatment groups. CONCLUSIONS: Reviparin, given in a very early stage of vascular injury, compares favourably with unfractionated heparin/placebo, by reducing abrupt closure and acute-phase adverse outcome following PTCA. With respect to the evaluated risk factors for acute events, the positive effect of reviparin on early adverse outcome after PTCA may be due to improved antithrombotic properties as compared to unfractionated heparin.

Angina Pectoris↗
PubMed1998

Local Delivery of TGF-b Antibodies to Prevent Neointima Formation after Balloon Injury in a Pig Coronary Artery Model.

BACKGROUND: The formation of neointima after vessel injury results from smooth muscle cell proliferation and extracellular matrix secretion. This process is activated by multiple growth factor release. Among these, Transforming Growth Factor-b (TGF-b) has been shown to play an important role. We hypothesized that local delivery of TGF-b antibodies could reduce neointima formation after balloon angioplasty. METHODS AND RESULTS: Using autoperfusion double-balloon catheters (Baxter, Irvine, California), we infused polyclonal TGF-b antibodies in 30 minutes, immediately after oversized balloon angioplasty in pig coronary arteries. Eleven coronary arteries received 100 m anti-TGF-b and thirteen served as controls. Animals were sacrificed 10 weeks later; coronary segments were harvested and processed for histologic quantitative assessment of the neointima. The extent of injury was similar in treated versus control vessels (39% +/- 5% vs. 30% +/- 4%) and there was no difference in intimal thickening (0.63 +/- 0.19 mm for treated vs. 0.52 +/- 0.12 mm for controls). A previously validated restenosis injury index (ratio of neointimal area to total wall area over extent of injury) was also similar in both groups, 1.46 +/- 0.15 for treated versus 1.55 +/- 0.14 for controls. CONCLUSION: Local delivery of a single dose of TGF-b antibodies failed to demonstrate a benefit on neointima formation in a pig coronary artery model.

Journal Article↗
PubMed1997

Directional coronary atherectomy (DCA): a report from the New Approaches to Coronary Intervention (NACI) registry.

Directional coronary atherectomy (DCA) with the Simpson coronary atherocath seeks to debulk rather than simply displace obstructive tissue and is a means of enlarging the stenotic coronary lumen. This report from the New Approaches to Coronary Intervention (NACI) registry describes the experience of 1,196 patients who underwent DCA as the sole treatment for either native vessel or vein graft lesions. Device success (post-DCA residual stenosis <50% and > or =20% improvement) was achieved in 87.8%, with a lesion success rate (postprocedural residual stenosis <50% and > or =20% improvement) of 94.0%. The mean resultant stenosis after all interventions (by core laboratory) was 19%. Significant in-hospital complications occurred in 2.8% of patients with DCA attempts, including death 0.6%, Q-wave myocardial infarction (MI) 1.5%, and emergent coronary artery bypass graft surgery (CABG) 2.8%. At 1-year follow-up, cumulative mortality was 3.6%, with repeat revascularization in 28% (repeat percutaneous transluminal coronary angioplasty, 20.1%; CABG, 10.6%). This reflected percutaneous or surgical revascularization of the original lesion (target lesion revascularization) in 22.6% of patients. Subgroup analysis showed a lower lesion success rate and an increased complication rate for unplanned use, vein graft treatment, and treatment of a de novo (vs a restenotic) lesion. Multivariate analysis shows that diabetes mellitus, unstable angina, treatment of a restenotic lesion, and greater residual stenosis after the initial procedure were independent predictors of the composite endpoint of death/Q-wave MI/target lesion revascularization by 1-year follow-up. Among these generally favorable acute and 1-year results, the NACI directional atherectomy data confirm the "bigger is better" hypothesis: that lesions with a lower residual stenosis after a successful procedure had significantly fewer target lesion revascularizations between 30 days and 1 year, with no increase in major adverse events.

Atherectomy, Coronary↗
PubMed1997

Management of resistant coronary lesions by the cutting balloon catheter: initial experience.

Resistant coronary lesions remain a challenge for modern angioplasty. Classical approaches include high-pressure inflations, prolonged inflations, or balloon oversizing. More recently, new technologies like rotablator, atherectomy, or laser have been proposed as adjunct to balloon angioplasty for the treatment of these specific lesions. However, all these technologies remain more difficult to handle, costly, and they do not offer long-term benefit over conventional methods. Therefore, a simple device such as the cutting balloon catheter which has been developed from a standard over the wire balloon catheter, may prove to be useful in resistant coronary lesions. We present our single center experience using the new cutting balloon catheter in six resistant lesions.

Aged↗
PubMed1997

[Low molecular weight heparin, reviparin, after PTCA: results of a randomized double-blind, standard heparin and placebo controlled multicenter study (REDUCE Study].

BACKGROUND: Unfractionated heparin and its low molecular fragments possess antiproliferative effects and have been shown to reduce neointimal smooth muscle cell migration and proliferation in response to vascular injury in experimental studies. OBJECTIVES: The specific objective of the REDUCE trial was to evaluate the effect of a low molecular weight heparin on the incidence and occurrence of restenosis in patients undergoing percutaneous transluminal coronary angioplasty. METHODS: The REDUCE trial is an international prospective, randomized, double-blind, multicenter study. Twenty-six centers in Europe and Canada enrolled 625 patients with single lesion coronary artery obstructions suitable for PTCA. Three hundred and six patients received reviparin as a 7000 U bolus before PTCA followed by 10,500 U as an infusion over 24 hours and then twice a day 3500 U s.c. application for 28 days. The 306 patients in the control group received a bolus of 10,000 U unfractionated heparin followed by an infusion of 24,000 U over 24 hours. These patients then received 28 days of s.c. placebo injections. The primary endpoints were efficacy (defined as a reduction in the incidence of major adverse events, i.e., death, myocardial infarction, need for reintervention or bypass surgery), absolute loss of minimal luminal diameter, and incidence of restenosis during the observation period of 30 weeks after PTCA. RESULTS: Using the intention-to-treat analysis for all patients, 102 patients (33.3%) of the reviparin group and 98 patients (32%) of the control group have reached a primary clinical endpoint (relative risk = 0.98; 95% confidence limit, 0.88-1.09; p = 0.707). Likewise, no difference in late loss of minimal luminal diameter was evident for either group. Acute events within 24 hrs occurred in 3.9% of the reviparin group and in 8.2% of the control group (relative risk = 0.49; 95% confidence limit, 0.26-0.92; p = 0.027) during or immediately after the initial procedure. In the control group, 8 major bleedings occurred, and in the reviparin group, 7 major bleeding complications were observed within 35 days after PTCA. CONCLUSIONS: Reviparin use during and after coronary angioplasty did not reduce the occurrence of major clinical events or the incidence of angiographic restenosis over 30 weeks.

Adult↗