Biomedical subjects

Wolfgang Sperker

Publications and source records attributed to Wolfgang Sperker.

16 recordsLinked to original sources

PubMed2006

Platelet activation and high tissue factor level predict acute stent thrombosis in pig coronary arteries: prothrombogenic response of drug-eluting or bare stent implantation within the first 24 hours.

Increased thrombogenicity of drug-eluting stents (DESs) has recently been reported. The aim of the present study was to investigate the prothrombogenic effect of DESs and Bare stents, and determine factors predictive of acute stent thrombosis (AST) in preclinical experiments using new stent design or coating. Circulating pre- and post-stenting parameters of platelet activation (mean platelet volume, MPV; platelet distribution width, platelet large cell ratio), thrombin activation (thrombin-antithrombin complex, TAT and prothrombin fragments, F1+2), tissue factor antigen (TF-ag) and -activity (TF-act) and plasminogen activator inhibitor-1 (PAI-1) were measured in 141 consecutive pigs. Stent implantations were performed after pretreatment with aspirin and clopidogrel with unfractionated heparin anticoagulation. Nineteen pigs (groups AST-DES, n = 12; and AST-Bare, n = 7) died mean 6.3 +/- 2.9 h after stent implantation from AST. The remaining 122 control (C) pigs (groups C-DES, n = 76, and C-Bare, n = 46) survived the 1-month follow-up. Non-significantly elevated levels of post-stent F1+2 and TAT were measured in AST groups. Post-stenting MPV was increased significantly in the groups ASTDES and AST-Bare as compared with the groups C-DES and C-Bare (11.73 +/- 1.12 and 11.6 +/- 0.68 vs. 8.85 +/- 0.78 and 9.04 +/- 0.81 fL; p < 0.001), similarly to TF-ag (189.1 +/- 87.5 and 127 +/- 34.9 vs. 42.5 +/- 24.6 and 35.3 +/- 37.6 pg/ml; p < 0.001, respectively), Tfact (3.23 +/- 0.95 and 2.73 +/- 1.68 vs. 1.43 +/- 1.12 and 1.61 +/- 1.31 pM; p < 0.01, respectively) and PAI-1 (99.1 +/- 15.8 and 99 +/- 14.7 vs.53.4 +/- 40.2 and 46.9 +/- 42.4 ng/ml;p < 0.01, respectively). Multivariate analysis revealed elevated post-stenting plasma levels of TF-ag (p = 0.016) and MPV (p = 0.001) as independent risk factors for developing AST within the first 24 h in a porcine coronary stent model.

Angiography↗

PubMed2006

Paradoxical effects of aurintricarboxylic acid and RG-13577: acute thrombosis and in-stent stenosis in a passive-coated stent.

PURPOSE: To investigate if a platelet inhibitor (aurintricarboxylic acid [ATA]) and a heparin-mimicking antagonist (RG-13577) of basic fibroblast growth factor 2 (bFGF2) could be combined as a stable compound and attached to conventional bare metal stents to hinder thrombus formation and inflammatory reactions of stenting. METHODS: Fifteen domestic pigs were stented with RG-13577/ATA-coated (n=6), ATA-coated (n=12), and bare metal stents (n=12) in the left anterior descending (LAD) and left circumflex (LCX) coronary arteries. All surviving pigs were evaluated with contrast angiography and intravascular ultrasonography (IVUS) after 4 weeks. Histological analysis of the stented arteries was performed after hematoxylin-eosin staining. Tissue factor (TF) staining and scanning electron microscopy (SEM) were performed in animals with acute stent thrombosis. RESULTS: Five of the 6 animals receiving an RG-13577/ATA-coated stent experienced acute stent thrombosis, while no adverse events occurred in the animals of the other 2 groups. Follow-up angiography did not show significant in-stent stenosis in either bare or ATA-coated stents. However, histomorphometry revealed larger neointimal area (3.54+/-0.69 mm2 versus 1.82+/-0.27 mm2, p<0.05) and outward plaque area (1.56+/-0.34 mm2 versus 0.61+/-0.12 mm2, p<0.05) in ATA-coated stents. Three-dimensional IVUS analysis showed analogous results, with significantly larger neointimal volume and outward plaque volume in ATA-coated stents. There was a slight increase in TF staining around the stent struts, while SEM showed increased platelet adhesion and activity in RG-13577/ATA-coated stents versus the ATA-coated and bare metal stents. CONCLUSION: RG-13577/ATA-coated stents lead to acute stent thrombosis. The ATA coating alone did not lead to acute events, but resulted in higher neointimal hyperplasia and expansive remodeling. These results underline the importance of preclinical studies before using new coated stents in human arteries.

Animals↗

PubMed2005

NOGA-guided analysis of regional myocardial perfusion abnormalities treated with intramyocardial injections of plasmid encoding vascular endothelial growth factor A-165 in patients with chronic myocardial ischemia: subanalysis of the EUROINJECT-ONE multicenter double-blind randomized study.

BACKGROUND: The aim of this substudy of the EUROINJECT-ONE double-blind randomized trial was to analyze changes in myocardial perfusion in NOGA-defined regions with intramyocardial injections of plasmid encoding plasmid human (ph)VEGF-A(165) using an elaborated transformation algorithm. METHODS AND RESULTS: After randomization, 80 no-option patients received either active, phVEGF-A165 (n=40), or placebo plasmid (n=40) percutaneously via NOGA-Myostar injections. The injected area (region of interest, ROI) was delineated as a best polygon by connecting of the injection points marked on NOGA polar maps. The ROI was projected onto the baseline and follow-up rest and stress polar maps of the 99m-Tc-sestamibi/tetrofosmin single-photon emission computed tomography scintigraphy calculating the extent and severity (expressed as the mean normalized tracer uptake) of the ROI automatically. The extents of the ROI were similar in the VEGF and placebo groups (19.4+/-4.2% versus 21.5+/-5.4% of entire myocardium). No differences were found between VEGF and placebo groups at baseline with regard to the perfusion defect severity (rest: 69+/-11.7% versus 68.7+/-13.3%; stress: 63+/-13.3% versus 62.6+/-13.6%; and reversibility: 6.0+/-7.7% versus 6.7+/-9.0%). At follow-up, a trend toward improvement in perfusion defect severity at stress was observed in VEGF group as compared with placebo (68.5+/-11.9% versus 62.5+/-13.5%, P=0.072) without reaching normal values. The reversibility of the ROI decreased significantly at follow-up in VEGF group as compared with the placebo group (1.2+/-9.0% versus 7.1+/-9.0%, P=0.016). Twenty-one patients in VEGF and 8 patients in placebo group (P<0.01) exhibited an improvement in tracer uptake during stress, defined as a >or =5% increase in the normalized tracer uptake of the ROI. CONCLUSIONS: Projection of the NOGA-guided injection area onto the single-photon emission computed tomography polar maps permits quantitative evaluation of myocardial perfusion in regions treated with angiogenic substances. Injections of phVEGF A165 plasmid improve, but do not normalize, the stress-induced perfusion abnormalities.

Algorithms↗

PubMed2005

Characterization of hibernating myocardium with NOGA electroanatomic endocardial mapping.

Because the terms "hibernation" and "viability" are not interchangeable, the recognition of hibernating myocardium within viable segments remained elusive for NOGA electroanatomic endocardial mapping. The aim of the present study was to determine the characteristics of hibernating myocardium in NOGA mapping. Baseline and follow-up endocardial mapping, thallium-201 myocardial perfusion scintigraphy at rest, and contrast ventriculography were performed in 28 patients who had proved viable myocardium before and 7.3 +/- 2.5 months after percutaneous coronary intervention. Significantly improved regional wall motion in the revascularized territory (region of interest) was confirmed in 9 patients (group 1) at follow-up (from -2.11 +/- 0.87 to -1.48 +/- 0.43 SD/chord, p <0.05), whereas no change in regional wall motion was observed in 19 patients (group 2; from -2.56 +/- 0.88 to -2.79 +/- 0.91 SD/chord). Average normalized thallium uptake at rest increased significantly in groups 1 and 2 after revascularization. A trend toward increased unipolar voltages in the region of interest was observed in group 1 at follow-up (from 10.6 +/- 3.5 to 11.7 +/- 4.0 mV, p = 0.073), whereas no change was observed in group 2 (from 8.7 +/- 4.4 to 8.9 +/- 3.8 mV). A significant increase in local linear shortening was measured only in group 1 (from 7.5 +/- 5.2% to 10.3 +/- 3.9%, p <0.05). Hibernating myocardial segments exhibited significantly higher unipolar voltages and late thallium uptake at rest at baseline. Receiver-operator characteristic analysis showed a mean unipolar voltage of 9.0 mV (predictive accuracy 0.708, common sensitivity and specificity 72%) in the region of interest for prediction of functional recovery. In conclusion, for characterizing the hibernating myocardium within viable segments, NOGA endocardial mapping offers on-line guidance for percutaneous coronary and noncoronary myocardial revascularization.

Aged↗

PubMed2004

Vascular remodeling in atherosclerotic femoral arteries: three-dimensional US analysis.

PURPOSE: To investigate the various modes of vascular remodeling of atherosclerotic femoral arteries and determine the associations between type of arterial remodeling and clinical data (age, sex, and medical history) and inflammatory parameters. MATERIALS AND METHODS: Intravascular ultrasonography (US) of the femoral arteries was performed in 50 patients with clinical symptoms of peripheral vascular disease. To determine the arterial remodeling mode (expansive remodeling [ER], involving compensatory enlargement of the artery, or constrictive remodeling [CR], involving vessel constriction during progression of atherosclerosis), the cross-sectional areas (CSAs) of the external elastic membrane (EEM), lumen, and plaque-plus-media were measured every 0.1 mm by using three-dimensional reconstruction. Clinical, laboratory, and intravascular US data were compared in the different remodeling groups (dominant ER, dominant CR, or mixed remodeling) by using analysis of variance supplemented by Tukey-Kramer tests. Multivariate analysis was performed to test independent variables predicting dominant ER. RESULTS: Intravascular US revealed the parallel existence of ER and CR in all patients: Increases and decreases in EEM in response to plaque growth could be observed within the same artery. ER dominated in 13 (26%) patients, and CR dominated in 11 (22%) patients: At least 80% of EEM CSAs were higher or lower than the mean of the EEM CSAs of the segments proximal and distal to the lesion. Patients with dominant ER had higher levels of serum C-reactive protein (CRP) compared with levels in patients with dominant CR and patients with mixed remodeling (1.62 mg/dL +/- 2.05 [standard deviation] vs 0.19 mg/dL +/- 0.33 and 0.21 mg/dL +/- 0.39, respectively, P < .005). Multivariate analysis revealed high CRP level to be a significant independent predictor for dominant ER (P < .01). CONCLUSION: The parallel existence of ER and CR was found in all patients with peripheral atherosclerosis, with a dominance of vessel expansion in 26% of patients. Higher plasma CRP level was associated with dominant ER.

Aged↗

PubMed2004

[Long-term results of percutaneous transmyocardial laser revascularization therapy at the University of Vienna Medical Center].

INTRODUCTION: Percutaneous transmyocardial laser revascularization (PTMR) was used for treating patients with therapy refractory angina pectoris who are not amenable for angioplasty or bypass surgery ("no-option patients"). The aim of this study was to evaluate the short- and long-term results of PTMR-interventions performed at the University of Vienna between February 1999 and May 2000. PATIENTS AND METHODS: Twenty-four "no-option" patients underwent PTMR. The chronically ischemic myocardial areas were determined by perfusion scintigraphy; after coronary angiography and contrast ventriculography 10 patients were treated with the Biosense laser using 3D-NOGA-mapping guidance and 14 patients with the Eclipse laser using biplane fluoroscopic guidance. After an average follow-up period (FUP) of 7.7 +/- 4.2 months, all patients underwent perfusion scintigraphy, coronary angiography and contrast ventriculography. Global and regional left ventricular (LV) function were calculated by the area-length method. RESULTS: The ischemic myocardial areas of the patients were treated with an average of 16 laser points. In one patient, an intramural hematoma caused by the Biosense laser catheter was observed, in another patient the ventricular wall was perforated by the Eclipse laser (both events were resolved conservatively); during the in-hospital stay 2 patients suffered from severe angina pectoris and in one patient a pacemaker was implanted. During the 7-month-FUP one patient had a myocardial infarction; in one patient a stent implantation, in another one coronary bypass surgery had to be performed (in not-lasered areas), 2 patients died. Thus, the composite MACE rate was 33.3%. Angina class improved significantly during the FUP, but a trend to deterioration of global ejection fraction was observed. The rest and late rest myocardial perfusion remained unchanged. CONCLUSION: While the angina class of the patients improved significantly, no significant change of myocardial perfusion but a trend to deterioration of LV function after the FUP were observed.

Aged↗

PubMed2004

Short- and long-term clinical outcome after various stent implantation: overview of the results of uni- and multicenter stent registries.

The present study reports the results of the short- and long-term outcomes of prospective uni- and multicenter stent registries: Palmaz-Schatz (n = 140 patients), Ave-Micro and GFX (n = 280), Multilink Duet (n = 340), Multilink Tetra (n = 192), and Carbo (n = 140) Stent Registries, as well as the predictors and angiographic cutoff points predicting major adverse cardiac events (MACE) after different stent implantations. Significant decrease in subacute stent thrombosis (from 2.9% to 0) and MACE (from 35% to 8.3%) occurred as the improved stents, optimized stent implantation technique, and new postintervention drug therapy were introduced. The changes of angiographic cutoff values (postintervention minimal lumen diameter and preintervention reference diameter: from 2.9 and 3.1 mm for Palmaz-Schatz to 2.5 and 2.8 mm for Multilink Duet, Multilink Tetra, and Carbo stents) and clinical and angiographic factors predicting MACE indicated the change of traditional restenosis paradigm and that progress in clinical practice might be able to counterbalance unfavorable lesion and intervention-related characteristics.

Coronary Angiography↗

PubMed2003

Evaluation of myocardial perfusion and left ventricular function six months after percutaneous transmyocardial laser revascularization: comparison of two Ho-YAG laser systems with the same wavelength, but different energy delivery and navigation systems.

BACKGROUND AND OBJECTIVES: Myocardial perfusion and left ventricular function (LVF) were assessed after percutaneous transmyocardial laser revascularization (PTMR) in patients not amenable to conventional revascularization, with a comparison of two laser systems. STUDY DESIGN/MATERIALS AND METHODS: PTMR was performed with an Eclipse laser in 15 patients, and with a Biosense DMR in 10 patients. (201)Thallium scintigraphy, coronary angiography, and ventriculography were performed at baseline and at the 7.5+/-4.3-month follow-up. All patients in the Biosense DMR group and 10 in the Eclipse group underwent NOGA mapping before PTMR and after follow-up. RESULTS: The event-free survival rates were comparable, and the angina scores of all patients improved significantly, but more so in the Biosense DMR group than in the Eclipse group (1.2+/-1.1 vs. 2.3+/-0.9, P < 0.05). Both, the electrical activity assessed by NOGA mapping and the normalized (201)thallium uptake at redistribution improved significantly in the treated segments after Biosense DMR, while the global LVF decreased insignificantly in the Eclipse group. CONCLUSIONS: PTMR resulted in significant improvements in the clinical symptoms, but the electrical activity improved only in the Biosense DMR group, without transforming to a better LVF.

Aged↗

PubMed2003

Serial intravascular ultrasonographic measurements after implantation of biodegradable polymer-coated stents in porcine coronary arteries.

BACKGROUND: Biodegradable stent coatings provide a potential for local drug delivery at the time of vascular injury, while possible tissue toxicity is avoided through constant degradation, leaving behind a bare metal stent. DESIGN: Serial three-dimensional (3D) intravascular ultrasonographic results on bare Megaflex stents and biodegradable polymer-coated Megaflex stents (Hyper stents) (Eurocor, Bonn, Germany) were compared 1 and 4 weeks after intracoronary implantation in pigs. METHODS: Under general anaesthesia, the left anterior descending and circumflex coronary arteries of domestic pigs were stented with Megaflex and Hyper stents, using right femoral artery access. Control coronary angiography and intravascular ultrasonography (IVUS) were performed 1 and 4 weeks after stent implantation using left femoral artery access and right carotid artery access. After recording of angiographic and IVUS data, the pigs were allowed to recover. RESULTS: The 1- and 4-week IVUS follow-ups revealed less neointima formation with Hyper stents than with Megaflex stents: 1-week intimal volume, 11.8+/-0.93 compared with 15.02+/-4.18 mm3, P=0.065; intimal area, 0.81+/-0.06 compared with 1.1+/-0.16 mm2, P =0.003; maximal intimal thickness, 0.12+/-0.01 compared with 0.14+/-0.02 mm, P =0.049; 4-week intimal volume, 12.4+/-1.77 compared with 27.32+/-12.79 mm3, P =0.016; intimal area, 0.82+/-0.12 compared with 1.95+/-0.65 mm2, P=0.003; and maximal intimal thickness, 0.13+/-0.04 compared with 0.30+/-0.10 mm, P=0.003. CONCLUSIONS: Implantation of biodegradable polymer-coated (Hyper) stents results in significantly less neointima formation 1 and 4 weeks after intracoronary implantation than with bare Megaflex stents. Taking advantage of the good collateralization of femoral and carotid arteries of pigs, the use of different arterial accesses allows serial angiographic and 3D IVUS measurements on neointimal development without sacrificing the animals.

Animals↗

PubMed2003

Effects of radial stretch on target lesion revascularization after percutaneous coronary intervention: an intravascular ultrasound study.

OBJECTIVE: To analyze possible associations between radial stretch during coronary angioplasty and the incidence of target lesion revascularization (TLR). PATIENTS AND METHODS: Intravascular ultrasound images were obtained before and after revascularization in 182 native coronary lesions. The quantitative intravascular ultrasound parameters (external elastic membrane cross-sectional area [EEM-A], lumen areas [LA], plaque area [PA], calculated as EEM-A-LA, and changes between pre- and postinterventional LA [DLA], EEM-A [DEEM-A] and PA [DPA]) were correlated with the incidence of TLR. RESULTS: TLR was performed in 60 (33%) patients, while 122 (67%) patients remained event free. Postinterventional PA remained significantly larger in the TLR group than in the event-free group (9.2 +/- 3.3 mm2 versus 7.9 +/- 3.3 mm2; P=0.02). The radial stretch during intervention, expressed as DEEM-A, and the balloon to artery ratio was significantly larger in the TLR group (DEEM-A: 1.9 +/- 2.1 mm2 versus 1.3 +/- 2.0 mm2; P=0.03; balloon to artery ratio: 1.3 +/- 0.2 versus 1.0 +/- 0.5; P=0.04). Multivariate analysis revealed DEEM-A (P=0.01), DPA (P=0.03), diabetes (P=0.001, odds ratio 5.2, 95% CI 4.9 to 6.5) and adaptive remodelling (P<0.001, odds ratio 4.1, 95% CI 3.5 to 6.4) as independent predictors for TLR. CONCLUSION: Whereas patients in whom lumen gain is achieved primarily by plaque reduction with less wall stretch tend to remain event free, patients with significant radial stretch (ie, less reduction of the PA, but a radial outward shift of the plaque mass) experience a higher incidence of TLR.

Aged↗

PubMed2003

Inhibition of interleukin-1beta convertase is associated with decrease of neointimal hyperplasia after coronary artery stenting in pigs.

Inhibition of IL-1beta convertase has been shown to decrease inflammation and apoptosis, which are features of the neointimal development after vascular interventions. The aim of our study was to reduce neointimal proliferation after stenting of the porcine coronary artery, using the irreversible IL-1beta convertase and caspase-1 inhibitor acetyl-tyrosinyl-valyl-alanyl-aspartyl-chloromethyl-ketone (Ac-YVAD-cmk). Before coronary stent implantation, 8 pigs received an intracoronary infusion of 50 mg Ac-YVAD-cmk into the left coronary artery (group 1, n = 8), while 8 animals served as untreated controls (group 2). After 4 weeks, coronary angiography and intracoronary ultrasound (IVUS) with 3D measurements were performed. IVUS revealed a smaller in-stent intimal volume (27.3 +/- 11.6 vs. 75.8 +/- 18.4 mm3, p < 0.005) and a decreased maximal percentage area stenosis (36.1 +/- 8.5 vs. 69.0 +/- 8.2%, p < 0.001) in group 1 vs. group 2. A smaller maximal neointimal thickness (0.63 +/- 0.28 vs. 1.75 +/- 0.94 mm, p < 0.005) and a decreased maximal neointimal area (2.14 +/- 1.29 vs. 5.03 +/- 1.92 mm2, p < 0.005), assessed by computerized planimetry, were found in group 1 vs. group 2. Lower apoptotic indices of the neointimal cells were observed in the treated animals (3.0 vs. 13.4% of total intimal cells, p < 0.05). The coronary arterial tissue IL-1beta level was significantly decreased in the animals treated with Ac-YVAD-cmk (0.254 +/- 0.162 vs. 0.463 +/- 0.307 pg/mg protein, p < 0.05), and exhibited a positive linear correlation (r = 0.581, p = 0.013) with the in-stent plaque volume. In conclusion, intracoronary administration of Ac-YVAD-cmk before coronary artery stenting results in significantly decreased neointimal hyperplasia due to the inhibition of local IL-1beta production and decreased neointimal apoptosis.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Coronary no-reflow is caused by shedding of active tissue factor from dissected atherosclerotic plaque.

Defined angiographically, no-reflow (NR) manifests as an acute reduction in coronary flow in the absence of epicardial vessel obstruction. One candidate protein to cause coronary NR is tissue factor (TF), which is abundant in atherosclerotic plaque and a cofactor for activated plasma coagulation factor VII. Scrapings from atherosclerotic carotid arteries contained TF activity (corresponding to 33.03 +/- 13.00 pg/cm(2) luminal plaque surface). Active TF was sedimented, indicating that TF was associated with membranes. Coronary blood was drawn from 6 patients undergoing coronary interventions with the distal protection device PercuSurge GuardWire (Traatek, Miami, FL). Fine particulate material that was recovered from coronary blood showed TF activity (corresponding to 91.1 +/- 62.16 pg/mL authentic TF). To examine the role of TF in acute coronary NR, blood was drawn via a catheter from coronary vessels in 13 patients during NR and after restoration of flow. Mean TF antigen levels were elevated during NR (194.3 +/- 142.8 pg/mL) as compared with levels after flow restoration (73.27 +/- 31.90 pg/mL; P =.02). To dissect the effects of particulate material and purified TF on flow, selective intracoronary injection of atherosclerotic material or purified relipidated TF was performed in a porcine model. TF induced NR in the model, thus strengthening the concept that TF is causal, not just a bystander to atherosclerotic plaque material. The data suggest that active TF is released from dissected coronary atherosclerotic plaque and is one of the factors causing the NR phenomenon. Thus, blood-borne TF in the coronary circulation is a major determinant of flow.

Angioplasty↗

PubMed2002

Short- and long-term results of emergency and elective percutaneous interventions on left main coronary artery stenoses.

In this prospective study, we analyzed the short- and long-term outcomes of percutaneous interventions on significant left main coronary artery (LM) stenoses. Between January 1998 and June 2000, 18 patients underwent emergency interventions on unprotected LM stenoses (group 1), while 15 patients had elective interventions on protected LM stenoses (group 2). Despite a procedural success of 88.9% in group 1, event-free in-hospital and mortality rates were 50.0% and 38.9%. After 6.4 +/- 4.4 months of follow-up, late event-free survival and mortality rates were 33.3% and 38.9%. In group 2, procedural success was 100%, with 100% event-free in-hospital survival; late event-free survival and mortality rates were 93.3% and 0% after 6.7 +/- 4.1 months of follow-up. Emergency interventions on LM stenoses remain a procedure with high acute and mid-term mortality. In spite of the high rate of major adverse cardiac events, an acceptable long-term survival can be achieved.

Aged↗

PubMed2002

Case-based distance measurements for the selection of controls in case-matched studies: application in coronary interventions.

In case-based studies, controls are retrospectively assigned to patients in order to permit a statistical evaluation of the study results through a comparison of the main outcome measures for the patient and retrieved control groups. Inappropriate selection of the controls by using false retrieval parameters or a false algorithm might lead to an incorrect data analysis and a false interpretation of the results. The main hypothesis of the presented study was that, if the matching baseline parameters were at least nearly perfectly selected, then the outcomes of the matched pairs should be similar, or no significant differences in study outcome should be observed between the patients and the matched controls. In the present study, the case-based domain was created from 1566 patients who had undergone intracoronary stent implantation. Uni- and multivariate logistic regression analysis determined nine significant predictors (matching variables) for the occurrence of major adverse cardiac events. An additional 425 consecutive patients undergoing intracoronary stent implantation were then matched with all the potential controls from the database by calculating the individual distance between the patient and the matched control on the basis of the elaborated retrieval algorithm. To test the matching hypothesis, different distance measurements, and an altered outcome and retrieval process were examined. With "flexible" distance measurements, the mean distance between the patients and the first matched controls was 1.31. The major adverse cardiac events were compared in the patient and matched control groups. The best sensitivity and specificity values of the matching system could be achieved in matched pairs with the distance < or =3.00 (95.1% of all patients). On the further stepwise exclusion of the matched pairs exhibiting a distance greater than 2 and 1, then the number of "matchable" controls and the specificity of our matching concept decreased considerably. When the short- or mid-term outcome was compared by using the long-term follow-up matching parameters, no correlation could be found between the treated subjects and controls, indicating that for the other study, main measures of other appropriate parameters must be selected, and demonstrating the importance of the outcome-oriented selection of the retrieval parameters. Furthermore, the outcome measures of the patients and randomly (non-systematically) selected controls did not correlate, revealing the impossibility of drawing correct study conclusions from a non-matched, randomly assigned pairs. In conclusion, the sensitivity and specificity of the matching program, and the study conclusions depend on the appropriately predefined matching parameters and retrieval algorithm.

Algorithms↗

PubMed2002

Mechanism of lumen gain during coronary stent deployment in diabetic patients compared with non-diabetic patients.

BACKGROUND: Diabetic patients show an increased incidence of restenosis after coronary angioplasty than non-diabetic patients. This may be because of differences in the mechanism of lumen gain during coronary revascularization in this population cohort. DESIGN: This study analyses the mechanism of lumen gain during coronary stent deployment in diabetic patients compared with non-diabetic patients with intravascular ultrasound (IVUS). METHODS: IVUS images were obtained prior to and after revascularization in 26 diabetic and 97 non-diabetic patients. The external elastic membrane cross-sectional area (EEM) and lumen cross-sectional area (LA) were measured. Plaque area (PA) was calculated as EEM minus LA. Differences between pre- and post-LA (deltaLA), EEM (deltaEEM) and PA (deltaPA) were calculated. RESULTS: Pre-interventional PA (diabetic patients: 12.4 +/- 4.4 mm2 compared with non-diabetic patients: 10.7 +/- 3.6 mm2, = 0.04) and pre-interventional EEM (15.5 +/- 4.4 mm2 compared with 13.6 +/- 3.7 mm2 respectively, P = 0.02) were larger in the diabetic group. Postinterventional PA (10.2 +/- 3.2 mm2 compared with 8.0 +/- 3.4 mm2, P = 0.004) was also larger and postinterventional LA (6.3 +/- 2.2 mm2 compared with 7.4 +/- 2.4 mm2 = 0.04), deltaEEM (0.9 +/- 1.8 mm2 compared with 1.8 +/- 1.8 mm2 P = 0.04) and deltaLA (3.1 +/- 1.6 mm2 compared with 4.2 +/- 2.2 mm2, P = 0.03) were smaller in the diabetic group. The diabetic group exhibited longer lesion lengths (P = 0.04) and a higher inflation pressure was used during revascularization in this patient cohort (P = 0.02). CONCLUSION: Diabetic patients have less reduction of PA during revascularization and because the vessel wall cannot be stretched outwards despite higher inflation pressure, postinterventional LA remains smaller than in the non-diabetic population cohort. This might be a rudiment for consideration of different treatment strategies such as cutting balloon or atherectomy prior to stenting in this population group in order to achieve better procedural outcome.

Aged↗

PubMed2002

Usefulness of intravascular ultrasound-guided histological measurements after stenting in porcine coronary artery.

BACKGROUND: We evaluated the usefulness of intravascular ultrasound (IVUS) in the non-uniform distribution of in-stent neointimal hyperplasia, comparing macroscopic measurements with IVUS-guided histomorphometry. METHODS: Coronary stenting was performed in 45 left coronaries of 39 pigs, using 18 Tenax (Biotronik Gmbh and Co., Berlin, Germany), 11 bare Genius (Eurocor, Bonn, Germany), 10 polymer-coated Genius (Eurocor) and six Biodivysio Matrix LO (Biodivysio Ltd, Farnham, Surrey, UK) stents. After 4 weeks, coronary angiography and IVUS with automatic pullback were performed. IVUS images were analysed using three-dimensional analysis (EchoPlaque 2; INDEC Systems Inc., Mountain View, California, USA). The stented segments were formalin fixed, embedded in Technovit 9100 and cut to 4-8 microm thick slides. The most diseased in-stent segment was 4.49 +/- 4.54 mm away from the distal stent edge assessed by IVUS. Sections of these segments were stained for histomorphometry. RESULTS: A significant correlation was found between IVUS-guided histomorphometry and three-dimensional IVUS measurements of maximal intimal thickness (r = 0.6985, P < 0.005) and area (r = 0.7736, P < 0.001). Macroscopic measurements resulted in comparable maximal intimal thickness (0.83 +/- 0.43 mm compared with 0.81 +/- 0.46 mm) and area (4.44 +/- 1.73 mm2 compared with 3.45 +/- 1.55 mm2) by IVUS and histomorphometry, respectively. Although stent length, diameter, nominal inflation pressure and time and injury score did not differ between the stents, bare Genius stents resulted in significant smaller neointimal volume compared to Tenax, polymer-coated Genius and Biodivysio stents: 24.46 +/- 4.98 mm3 compared with 59.18 +/- 26.41, 60.46 +/- 10.03 and 61.41 +/- 16.27 mm3, respectively (P < 0.05). CONCLUSION: The significant correlation between IVUS-guided histomorphometry and IVUS measurements confirms the usefulness of IVUS in evaluation of experimental in-stent restenosis. Implantation of bare Genius stents resulted in significant lower neointimal hyperplasia compared to Tenax, polymer-coated Genius or phosphorylcholine-coated Biodivysio stents.

Animals↗