The effect of intracoronary fibroblast growth factor-2 on restenosis after primary angioplasty or stent placement in a pig model of atherosclerosis

BACKGROUND: Therapeutic angiogenesis, if combined with primary percutaneous transluminal coronary angioplasty or stent placement, could improve the outcome of patients suffering from multifocal coronary disease. HYPOTHESIS: Because of the concern that angiogenic growth factors might promote restenosis, we studied the effect of a single intracoronary administration of recombinant fibroblast growth factor (rFGF)-2 on restenosis after balloon angioplasty and stent placement in a pig model of coronary atherosclerosis. METHODS: In 24 Yucatan minipigs, coronary lesions were induced by arterial injury and 3 months of atherogenic diet. After 3 months, repeat catheterization was performed with balloon dilation or stent placement at the injured sites, with a follow-up of 6 weeks. Results were monitored using quantitative angiography, intravascular ultrasound (IVUS), and histomorphometry. RESULTS: Intracoronary rFGF-2 2 microg/kg did not affect neointima formation or remodeling in this model. A small but significant aggravation of late lumen loss was observed in the reference segments of the rFGF-2-treated group. Angiographic and echographic late lumen loss, intimal hyperplasia, and arterial remodeling, as well as histologic neointima were all similar in the rFGF-2- and the vehicle-treated group. Confirming earlier studies from our group and those of others, stented arteries compared with balloon-dilated arteries had increased angiographic late lumen loss, a trend toward increased intimal hyperplasia and decreased remodeling. CONCLUSION: We conclude that rFGF-2 does not aggravate restenosis after balloon dilation or stenting in this pig model of coronary atherosclerosis. Future combinations of angioplasty and therapeutic angiogenesis in a single session should be pursued as a feasible and safe strategy.     

Carotid artery stent type influences duplex ultrasonography derived peak systolic velocity: findings of an in-vitro model.

OBJECTIVE: The goal of this study is to evaluate the effect of stenting on Doppler ultrasonography (DU) [velocity] signals in an in-vitro carotid model. BACKGROUND: Considerable debate exists about whether DU overestimates velocity signals and thus the degree of stenosis in previously stented carotid arteries. METHODS: Constant, pulsatile flow was simulated with an experimental circulatory system containing a nonstenotic ovine internal carotid artery segment. Peak systolic velocity (PSV) and peak diastolic velocity were measured with an intravascular flow wire (FW) and DU. Velocities were evaluated at five predetermined locations within the vessel immediately prior to and following stent placement. RESULTS: Eleven stents were implanted. DU-derived PSV increased significantly following placement of the X-Act stent (80+/-26 cm/sec [pre] vs. 102+/-29 cm/sec [post], P=0.02), while FW-derived PSV (65+/-23 cm/sec [pre] vs. 66+/-9 cm/sec [post], P=0.93) did not change. The Precise stent did not influence PSV with either method (DU: 76+/-28 cm/sec [pre] vs. 72+/-35 cm/sec [post], P=0.95;), while the Acculink stent showed a trend towards a reduction in DU (69+/-37 cm/sec [pre] vs. 51+/-10 cm/sec [post], P=0.075) and FW (50+/-27 cm/sec [pre] vs. 40+/-12 cm/sec [post], P=0.14) derived PSV. Peak diastolic velocity revealed similar trends as PSV signals depending on the type of stent used. CONCLUSIONS: Stent type may have significant impact on DU derived velocity signals. DU seems to overestimate PSV in carotid arteries treated with the X-Act stent, but not with the Precise or Acculink stent. Larger scale clinical comparison of various stent types and their impact on DU are needed in order to clarify the value of DU surveillance following carotid artery stenting.     

Intermediate follow-up following intravascular stenting for treatment of coarctation of the aorta.

BACKGROUND: We report a multiinstitutional study on intermediate-term outcome of intravascular stenting for treatment of coarctation of the aorta using integrated arch imaging (IAI) techniques. METHODS AND RESULTS: Medical records of 578 patients from 17 institutions were reviewed. A total of 588 procedures were performed between May 1989 and Aug 2005. About 27% (160/588) procedures were followed up by further IAI of their aorta (MRI/CT/repeat cardiac catheterization) after initial stent procedures. Abnormal imaging studies included: the presence of dissection or aneurysm formation, stent fracture, or the presence of reobstruction within the stent (instent restenosis or significant intimal build-up within the stent). Forty-one abnormal imaging studies were reported in the intermediate follow-up at median 12 months (0.5-92 months). Smaller postintervention of the aorta (CoA) diameter and an increased persistent systolic pressure gradient were associated with encountering abnormal follow-up imaging studies. Aortic wall abnormalities included dissections (n = 5) and aneurysm (n = 13). The risk of encountering aortic wall abnormalities increased with larger percent increase in CoA diameter poststent implant, increasing balloon/coarc ratio, and performing prestent angioplasty. Stent restenosis was observed in 5/6 parts encountering stent fracture and neointimal buildup (n = 16). Small CoA diameter poststent implant and increased poststent residual pressure gradient increased the likelihood of encountering instent restenosis at intermediate follow-up. CONCLUSIONS: Abnormalities were observed at intermediate follow-up following IS placement for treatment of native and recurrent coarctation of the aorta. Not exceeding a balloon:coarctation ratio of 3.5 and avoidance of prestent angioplasty decreased the likelihood of encountering an abnormal follow-up imaging study in patients undergoing intravascular stent placement for the treatment of coarctation of the aorta. We recommend IAI for all patients undergoing IS placement for treatment of CoA.     

Vascular stenting in normal and atherosclerotic rabbits. Studies of the intravascular endoprosthesis of titanium-nickel-alloy

Percutaneous transluminal balloon angioplasty would be more effective if the rate of recurrent stenosis were reduced. To evaluate the prevention of restenosis after percutaneous transluminal angioplasty, intravascular endoprosthetic stents of titanium-nickel-alloy were implanted transluminally in seven normal and 21 atherosclerotic rabbits. In normal rabbits, a 3.5-mm diameter stent was implanted in the aorta and a 2.5-mm diameter stent in the right iliac artery, which were followed with serial angiograms from 6 weeks (n = 7) to 8 months (n = 4). There was a mean stenosis of 13.1% in the 2.5-mm and 13.6% in the 3.5-mm stent. There was no significant narrowing compared with the adjacent control segments of artery; histopathology showed a thin, fibrous neointima with smooth muscle cells. Each atherosclerotic rabbit was balloon dilated at two separate stenotic sites; each site was 2.0 cm in length. The aortic site (with 28.8 +/- 13.8% mean stenosis [+/- SD]) was dilated with a 3.5-mm balloon, and the iliac site (with 36.5 +/- 14.2% stenosis) was dilated with a 2.5-mm balloon. In each site, an intravascular stent of corresponding diameter and 7-mm length was implanted in one half of the dilated segment, assigned randomly, and the other half served as the angioplasty control. Angiographically observed restenosis rates and the corresponding histopathology were similar in the atherosclerotic segments that had angioplasty alone versus the atherosclerotic segments that had angioplasty plus stenting. The mean neointimal thickness in the aortas and iliac arteries, respectively, measured 247 +/- 181 microns (+/- SD) and 218 +/- 77 microns after 6 weeks (n = 8) versus 321 +/- 168 and 308 +/- 189 microns after 20 weeks (n = 5, p = NS). At 20 weeks follow-up, there was 29.1 +/- 29.8% (median, 16.4%) stenosis in the aortic stent versus 38.9 +/- 24.1% (median, 34.0%) stenosis in the percutaneous transluminal angioplasty control segment of aorta (n = 5, p = NS) and 81.4 +/- 25.5% stenosis in the iliac artery stent versus 89.3 +/- 15.3% stenosis in the PTA control segment of the right iliac artery (n = 5, p = NS). Comparing stenotic arterial segments treated with angioplasty alone with angioplasty plus intravascular stenting in the atherosclerotic rabbits showed that there was no significant difference in either the histopathologic changes or the restenosis rates.     

Controlled Release of Heparin Reduces Neointimal Hyperplasia in Stented Rabbit Arteries: Ramifications for Local Therapy

Percutaneous coronary angioplasty is limited by neointimal hyperplasia and restenosis. Endovascular stenting has been proposed as a possible means of limiting this process. In practice stents have achieved early patency but are beset by early thrombosis and late restenosis. Heparin administered locally or systemically reduces smooth muscle cell hyperplasia following arterial injury in animals. Balloon-expandable stainless steel stents were placed in de-endothelialized rabbit iliac arteries to determine whether heparin released locally from perivascular matrices could reduce stent induced thrombosis and intimal hyperplasia. All animals received oral aspirin beginning 1 day prior to implantation and an IV bolus of heparin at balloon injury and stent placement. Heparin releasing ethylene-vinyl acetate copolymer matrices were placed adjacent to the stented portion of the artery in the treated group of rabbits. Thrombosis was evident in 30% of ten control arteries 14 days after stent placement and was reduced to 0% in nine segments receiving local heparin therapy (P < 0.05). Intimal hyperplasia was present in all experimental arterial sections, but total intimal area normalized for induced injury was reduced at 14 days from 12.6 ± 0.9 mm² in controls, to 6.8 ± 1.0 mm² in treated arteries (P < 0.001). Our results with perivascular drug administration may shed some light on the pathobiology of the vascular response to endovascular stent insertion and might assist in the design of novel means for enhancing the utilization of angioplasty and other interventional procedures.     

Intravascular ultrasound assessment of the renal artery

OBJECTIVE: To determine the feasibility and diagnostic value of catheter-based intravascular ultrasound imaging compared with angiography for visualizing renal artery structure. DESIGN: Renal artery images were obtained in patients with renal artery stenosis having percutaneous balloon angioplasty and in normal subjects by digital angiography and by a 20-MHz, mechanically driven, catheter-based, intravascular ultrasound imaging system. SETTING: A referral-based university hospital. PATIENTS: Four randomly selected normal subjects without known renal disease and four consecutive patients with known renal artery stenosis referred for percutaneous balloon angioplasty. INTERVENTIONS: Digital angiograms and intravascular ultrasound images of nine renal artery segments were obtained. In patients with renal artery stenosis, imaging was done before and after balloon angioplasty. MAIN RESULTS: Digital angiography and ultrasonography correlated closely in the determination of arterial lumen diameter (r = 0.81) and cross-sectional area (r = 0.83). However, ultrasonography provided structural information not shown by angiography. All normal arteries showed discrete intimal, medial, and adventitial wall layers by ultrasonography. In the five stenotic segments, angiography identified the cause of stenosis to be atherosclerosis in four patients and fibromuscular dysplasia in one patient. Ultrasound imaging, however, identified the disease process as atherosclerosis in three patients and as fibromuscular dysplasia in two patients. After renal angioplasty, ultrasonography identified three arterial dissections, only one of which was shown by angiography. CONCLUSIONS: These preliminary data indicate that catheter-based intravascular ultrasound imaging of the renal artery is feasible and correlates well with angiography in assessing renal artery size and also provides potentially important additional structural information that permits a better characterization of arterial pathology.     

肠系膜上动脉狭窄的腔内介入治疗4例

目的:探讨肠系膜上动脉(SMA)狭窄所致缺血性肠病的诊断和治疗方法,评估腔内介入治疗的安全性及临床效果.方法:4例SMA狭窄患者通过介入治疗技术行SMA球囊扩张(PTA)及腔内支架植入术,术后随访了3-32 mo,观察腔内治疗的效果以及预后情况.结果:4例患者支架植入均成功.3例采用1枚支架,1例采用2枚支架.有3例在术后1 wk内症状消失,恢复良好.最快者术后当天腹痛消失,第2天肠梗阻即解除.3例患者在术后3 mo至6 mo内体质量恢复至接近正常.1例虽然术后症状较前明显缓解,但仍有间歇腹部不适,体质量恢复不明显.1例患者在术后32 mo死于突发心肌梗死,其生前症状未复发.随访期间复查腹部血管超声未发现有SMA再狭窄.结论:腹部血管CTA,MRA及选择性血管造影对确诊SMA狭窄致肠缺血具有重要意义.血管腔内技术应用于肠系膜血管疾病的治疗,是一种安全有效的方法,具有创伤小,恢复快等特点.     

Effects of intravascular cryotherapy on vessel wall repair in a balloon-injured rabbit iliac artery model

OBJECTIVE: Although the application of cold energy, cryotherapy, has been shown to cause selective damage to cellular components with preservation of matrix structure resulting in less fibrosis in a variety of tissues, the effects of intravascular cryotherapy on vessel wall repair after balloon angioplasty are unknown. We sought to characterize the effects of cryotherapy application on vessel wall repair after balloon angioplasty and study the relationship between collagen accumulation in the vessel wall and late lumen loss as assessed by serial intravascular ultrasound. METHODS: The immediate, early (72 h) and late (10 weeks) effects of three intravascular cryotherapy application time periods (60, 120 and 240 s) after iliac artery balloon angioplasty ('cryotherapy') were compared with balloon angioplasty alone ('control') in 59 rabbits. Arterial lumen area was measured by intravascular ultrasound immediately after the procedure, at 72 h and at 10 weeks. Collagen content was calculated separately for intima and media/adventitia layers and correlated with late lumen loss. RESULTS: Cryotherapy produced average vessel wall temperature of -26 degrees C (range, -20 to -45 degrees C) and resulted in significantly larger lumen cross-sectional area (CSA) immediately after application (5.74+/-1.18 vs. 4.14+/-0.75 mm(2), P=0.008) but was not different than control arteries at 10 weeks. At 72 h, there was extensive cell loss in the medial and adventitial layers accompanied by increased macrophage infiltration in cryotherapy treated arteries compared to control. At 10 weeks, intimal hyperplasia was increased 2-fold in cryotherapy treated arteries. Collagen content was increased 2-fold in the medial/adventitial layers, and nearly 3-fold in the intima of cryotherapy treated arteries. Collagen content in arterial intima (P=0.01) as well as media/adventitia (P=0.005) positively correlated with late lumen loss. Foci of chondro- and osseous metaplasia and calcification were evident at the medial-adventitial junction in cryotherapy treated arteries at 10 weeks. CONCLUSION: Intravascular cryotherapy induced early arterial wall cell loss and late intimal hyperplasia, vascular fibrosis and chondro- and osseous metaplastic changes with no late beneficial effects on lumen area compared to balloon angioplasty alone. Collagen accumulation in all three layers of the vessel wall contributes to the development of late inward remodeling after balloon angioplasty.     

Intravascular ultrasound imaging before and after balloon angioplasty for pulmonary artery stenosis

Previous reports regarding intravascular ultrasound (IVUS) imaging of the pulmonary arteries in children and its application to balloon pulmonary angioplasty are limited. This study was designed to compare findings of IVUS imaging and those of angiography of the pulmonary artery before and after the balloon angioplasty procedure. Thirty patients had significant pulmonary artery stenosis and underwent balloon angioplasty. In all, of 34 branch pulmonary arteries were dilated. All patients underwent both angiography and IVUS imaging at the time of balloon angioplasty. The mean age at balloon angioplasty was 5.7 ± 4.0 yr. One echo-dense layer on IVUS was detected in 9% of the 34 stenotic vessels, and a two- or three-layered vascular wall pattern in 91%. The thickness of intima-medial layer (inner and middle layers) was greater than normal in 91% of stenotic vessels. After balloon angioplasty, intimal flaps and aneurysm were observed at 29 and 28 locations, respectively. Of these locations, the intimal flaps were detected by angiography in 44% and by IVUS in 100%; the aneurysm was detected by angiography in 61% and by IVUS in 93%. Media rupture was observed at 26 locations, and the change was detected only by IVUS. The present study suggests that intimal and medial changes in the pulmonary artery can be detected more precisely by IVUS than by angiography. Cathet. Cardiovasc. Intervent. 46:68–78, 1999. © 1999 Wiley-Liss, Inc.     

Restenosis following placement of an intracoronary heparin treated tantulum stent in the hyperlipidemic miniature swine model

Restenosis persists as an important factor limiting a favorable long term outcome following mechanical revascularization. The objective of the present study was to compare the effects of an intracoronary heparin treated tantalum prototype stent and balloon angioplasty on intimal hyperplasia, luminal diameter, and thrombosis in a porcine restenosis model. Male miniswine maintained on a high cholesterol diet and 325 mg aspirin per day underwent cardiac catheterization and oversized balloon injury to the right and left circumflex coronary arteries. Two weeks later one artery was either balloon injured again or implanted with a stent. No additional anticoagulation following stent placement was given, however aspirin was continued throughout the study. At four weeks, the coronary arteries were harvested and prepared for histologic examination and blinded quantitative morphometric analysis. The prototype stent was successfully deployed in 10 coronary arteries. Histological examination at explant revealed no evidence for thrombus or platelet aggregation. The angiographic luminal diameter of stented vessels was not significantly different from the diameter measured prior to implantation. In contrast, the angiographic diameter of balloon injured vessels was significantly decreased (4.4 +/- 0.4 mm2, balloon injured, vs. 5.8 +/- 3.3 mm2, control; p < 0.05). Stented arteries showed significantly more intimal hyperplasia, compared to balloon injured vessels (2.99 +/- 0.58 mm2 intimal area, stented arteries vs. 0.38 +/- 0.15 mm2 intimal area, control arteries; p < 0.05). In conclusion, heparin treated tantalum wire prototype intracoronary stents were successfully deployed in swine coronary arteries with no evidence for thrombus formation. Despite a significant intimal response, luminal diameter was preserved in stented vessels. The data suggest that a heparin treated tantalum wire prototype intracoronary stent may be an effective method of coronary revascularization that results in the preservation of luminal diameter without thrombotic occlusion.     

低能量红激光局部照射预防血管成形术后再狭窄的实验研究

目的评价低能量红激光局部照射对血管成形术后再狭窄的预防作用。方法对雄性新西兰白兔进行腹主动脉和髂动脉球囊拉伤（单纯拉伤组５０只）和拉伤后低能量密度的红激光局部照射（激光照射组５０只）。两组分别于术后３天、１周、２周、４周和８周分批进行血管病理形态学、氚标记胸腺嘧啶核苷（３ＨＴＤＲ）渗透实验和血管造影检查。结果血管拉伤后８周造影显示,激光照射组血管最小内径显著大于单纯拉伤组（Ｐ＜００５）;血管狭窄程度明显减低（Ｐ＜００５）;病理形态学分析表明,两组血管损伤程度相同,与单纯拉伤组相比,激光照射后血管内膜增生受到显著抑制,血管壁３ＨＴＤＲ渗透量减少,外弹力膜围绕面积增大,管腔狭窄程度明显减轻。结论低能量红激光局部照射可以显著减少血管成形术后再狭窄的形成。     

Intravascular Ultrasound Predictors of Angiographic Restenosis in Lesions Treated With Palmaz-Schatz Stents

Objectives. This study sought to evaluate the clinical, procedural, preinterventional and postinterventional quantitative coronary angiographic (QCA) and intravascular ultrasound (IVUS) predictors of restenosis after Palmaz-Schatz stent placement.Background. Although Palmaz-Schatz stent placement reduces restenosis compared with balloon angioplasty, in-stent restenosis remains a major clinical problem.Methods. QCA and IVUS studies were performed before and after intervention (after stent placement and high pressure adjunct balloon angioplasty) in 382 lesions in 291 patients treated with 476 Palmaz-Schatz stents for whom follow-up QCA data were available 5.5 ± 4.8 months (mean ± SD) later. Univariate and multivariate predictors of QCA restenosis (≥50% diameter stenosis at follow-up, follow-up percent diameter stenosis [DS] and follow-up minimal lumen diameter [MLD]) were determined.Results. Three variables were the most consistent predictors of the follow-up angiographic findings: ostial lesion location, IVUS preinterventional lesion site plaque burden (plaque/total arterial area) and IVUS assessment of final lumen dimensions (whether final lumen area or final MLD). All three variables predicted both the primary (binary restenosis) and secondary (follow-up MLD and follow-up DS) end points. In addition, a number of variables predicted one or more but not all the end points: 1) restenosis (IVUS preinterventional lumen and arterial area); 2) follow-up DS (QCA lesion length); and 3) follow-up MLD (QCA lesion length and preinterventional MLD and DS and IVUS preinterventional lumen and arterial area).Conclusions. Ostial lesion location and IVUS preinterventional plaque burden and postinterventional lumen dimensions were the most consistent predictors of angiographic in-stent restenosis.     

A follow-up study of balloon angioplasty and de-novo stenting in Takayasu arteritis

Percutaneous balloon angioplasty (PTBA) is a universally accepted mode of therapy for stenotic coronary and peripheral arterial lesions. To establish the role of PTBA and stent placement in patients with Takayasu's arteritis (TA), these procedures were performed in 20 patients with TA. All patients received steroids, aspirin and ticlodipine (for stent placement) prior to procedure. Angioplasty was carried in patients with symptomatic stenotic vessel of more than 70% of normal diameter or a peak systolic gradient of more than 50 mm across stenotic aortic lesion. Stenting was performed for ostial lesion, long segment lesion or incomplete relief of stenosis and dissection following angioplasty. Carotid angioplasty and stenting was performed in five patients, aortic angioplasty in nine patients, aortic angioplasty and stenting in four patients, renal angioplasty in three patients, renal angioplasty and stenting in two patients and subclavian angioplasty in two patients, subclavian, angioplasty and stenting in three patients and coronary angioplasty and stent placement in one patient. The procedure was successful in all but one patient. On following up, two patients with carotid stent placement had restenosis. A saccular aneurysm developed at the lower end of stent in one patient with aortic stent placement. The PTBA with or without stent placement is a safe and effective method for relief of stenotic lesion in patients with TA.     

Management of coronary artery rupture: Covered stent or microcoil embolization

The management of three cases of coronary artery rupture is described: (1) after high-pressure balloon angioplasty following uneventful placement of three Gianturco-Roubin stents, (2) following balloon angioplasty of an occluded diagonal branch, and (3) subsequent to rotational ablation of a left main and proximal circumflex arteries. Placement of an autologous veincovered Palmaz stent or microcoil embolic vessel occlusion solved each problem. In each case, emergency surgery was avoided; subsequent management, including anticoagulation (when indicated), was performed without incident. This is the first communication detailing correction of a coronary vessel rupture with an autologous vein-covered stent or by microcoil embolic vessel occlusion.     

Randomized comparison of coronary stenting with optimal balloon angioplasty for treatment of lesions in small coronary arteries.

AIMS: Angioplasty of lesions in small coronary arteries remains a significant problem because of the increased risk of restenosis. The aim of this study was to compare the efficacy of elective coronary stent placement and optimal balloon angioplasty in small vessel disease. METHODS: One hundred and twenty patients with lesions in small coronary arteries (de novo, non-ostial lesion and reference diameter <3 mm) were randomly assigned to either balloon angioplasty or elective stent placement (7-cell NIR stent). The primary end-point was restenosis at 6 months follow-up. Optimal balloon angioplasty was defined as diameter stenosis less than or = 30% and the absence of major dissection after the angioplasty, and crossover to stenting was allowed. RESULTS: Baseline clinical and angiographic characteristics were similar in the two groups. Procedure was successful in all patients, and in-hospital events did not occur in any patient. However, 12 patients in the angioplasty group were stented because of suboptimal results or major dissection. Postprocedural lumen diameter was significantly larger in the stent group than in the angioplasty group (2.44 +/- 0.36 mm vs 2.14 +/- 0.36, P<0.05, respectively), but late loss was greater in the stent group (1.12 +/- 0.67 mm vs 0.63 +/- 0.48, P<0.01, respectively). The angiographic restenosis rate was 30.9% in the angioplasty group, and 35.7% in the stent group (P = ns). Clinical follow-up was available in all patients (15.9 +/- 5.7 months) and clinical events during the follow-up were similar in both groups. CONCLUSIONS: These results suggest that optimal balloon angioplasty with provisional stenting may be a reasonable approach for treatment of lesions in small coronary arteries.     

Ultrasound velocity criteria for carotid in-stent restenosis.

OBJECTIVE: To examine duplex ultrasound (US) criteria for carotid in-stent restenosis (ISR). BACKGROUND: Carotid artery stent (CAS) placement is an alternative to surgery for the treatment of carotid stenosis in high surgical risk patients. US is the primary method used to follow carotid stent patency. This study investigates US velocity measurements in carotid ISR. METHODS: Two hundred sixty consecutive patients with CAS placement from June 2000 to June 2004 were followed with serial US. ISR was determined by using the standard US velocity criteria for nonstented carotid artery using peak systolic velocity (PSV), end-diastolic velocity (EDV), and internal carotid artery to common carotid velocity ratio (ICA/CCA ratio). Patients suspected of having carotid ISR > or =50% by US, underwent invasive angiography with stenosis graded by NASCET criteria. Results were compared to patients with nonstented carotid artery stenosis using Two-tailed Student's t-test. RESULTS: PSV and ICA/CCA ratio increased to a greater degree in ISR. In 50-69% stenotic arteries, the mean ICA/CCA ratio was 2.76 +/- 0.7 in the ISR group compared to 2.04 +/- 0.3 in the nonstented carotid group (P < 0.05). In > or =70% stenotic arteries, there were increases in PSV (520 +/- 93 vs. 362 +/- 60, P < 0.05) and ICA/CCA ratio (7.58 +/- 2 vs. 4.51 +/- 1.3, P < 0.05) in ISR versus nonstented carotid arteries, respectively. CONCLUSION: PSV and ICA/CCA ratio in ISR increased to a greater extent for angiographic stenosis > or =50%. PSV 240 cm/sec and ICA/CCA ratio 2.45 are optimal thresholds for > or =50% ISR, and PSV 450 cm/sec and ICA/CCA ratio 4.3 are optimal thresholds for > or =70% ISR.     

Effect of intracoronary stenting on intimal dissection after balloon angioplasty: results of quantitative and qualitative coronary analysis

The effect of the Palmaz-Schatz stent on the angiographic appearance and residual luminal stenosis in patients with intimal dissection after balloon angioplasty was evaluated in 84 consecutive patients (90 lesions). Coronary angiography was performed before angioplasty, after conventional angioplasty and after stent implantation. The degree of intimal disruption was assessed as follows: grade 0, no dissection; grade 1, simple dissection (intraluminal linear defect or extraluminal cap extravasation); or grade 2, complex dissection (nonlinear spiral defect or luminal defect with multiple irregular borders). Quantitative coronary analysis of digitized cineangiograms was performed with use of a computerized automatic edge detection algorithm. After balloon angioplasty, 31 (34%) of 90 lesions demonstrated intimal dissection (18 simple, 13 complex). After stent implantation, intimal dissection improved by greater than or equal to 1 grade in 29 (94%) of the 31 lesions with 27 (87%) reduced to grade 0 (that is, no dissection). Dissection grade improved after stenting in 16 (89%) of 18 simple dissections and in all 13 complex dissections. Mean diameter stenosis was 77 +/- 17% before angioplasty, 47 +/- 17% after angioplasty and 14 +/- 10% after stenting (before angioplasty vs. after angioplasty and after angioplasty vs. after stenting, p less than 0.0001). In conclusion, intracoronary stenting is effective in reducing the residual luminal stenosis and in improving the angiographic appearance of intimal dissections after conventional balloon angioplasty.     

Tissue proliferation within and surrounding Palmaz-Schatz stents is dependent on the aggressiveness of stent implantation technique

In-stent restenosis is entirely due to intimal hyperplasia. Histologic studies have indicated that intimal hyperplasia is related to the arterial injury induced during stent implantation. We used intravascular ultrasound (IVUS) imaging to study whether tissue proliferation inside and surrounding stents is related to the aggressiveness of the implantation technique. After intervention and follow-up (mean 5.6 +/- 3.7 months), serial IVUS imaging was performed in 102 native artery stented stenoses in 91 patients. Measurements at 5 predetermined segments within each stented lesion included external elastic membrane, stent, and lumen cross-sectional areas (CSAs). Calculations included mean plaque CSA growth outside of the stent (external elastic membrane-stent) and mean neointimal hyperplasia CSA and thickness within the stent (stent-lumen). Stenoses were categorized depending on the aggressiveness of stent placement (group 1, adjunct percutaneous transluminal coronary angioplasty pressure < 16 atm and/or balloon/artery ratio < 1.1; group 2, adjunct percutaneous transluminal coronary angioplasty pressure > or = 16 atm and balloon/artery ratio > or = 1.1). An aggressiveness score was calculated as balloon/artery ratio x inflation pressure. Mean intimal hyperplasia CSA (2.9 +/- 1.5 vs 2.2 +/- 1.6 mm2, p = 0.028), mean intimal hyperplasia thickness (0.34 +/- 0.19 vs 0.25 +/- 0.19 mm, p = 0.012), and mean peristent tissue growth CSA (2.5 +/- 1.0 vs 1.1 +/- 1.4 mm2, p = 0.003) were significantly greater in group 2 stenoses. In addition, intimal hyperplasia CSA and thickness correlated significantly with balloon/artery ratio x inflation pressures: r = 0.305, p = 0.002 and r = 0.329, p = 0.0007, respectively, as did peristent tissue proliferation CSA (r = 0.466, p = 0.001). Tissue proliferation inside and surrounding stents may be related to aggressiveness of the stent implantation technique.     

In vitro validation of three-dimensional intravascular ultrasound for the evaluation of arterial injury after balloon angioplasty.

OBJECTIVES. The hypothesis of this study was that three-dimensional ultrasound imaging would facilitate the evaluation of arterial dissection after balloon angioplasty. BACKGROUND. The presence and extent of arterial dissection occurring at the time of balloon angioplasty may be important predictors of abrupt vessel closure or late restenosis. METHODS. Forty-one human arterial segments obtained after death were imaged in an in vitro system at physiologic pressure (80 to 100 mm Hg) before and after balloon angioplasty. Images were acquired with a 20- to 30-MHz mechanical intravascular ultrasound imaging system (Cardiovascular Imaging Systems) with a constant pullback technique (1 mm/s). Standard 0.5-in. (1.27-cm) video tapes were used for data storage and later playback for analog to digital conversion. Digitized data were reconstructed to three-dimensional images with use of voxel space modeling. The vessels were opened longitudinally and subjected to pathologic examination, photographed and classified histologically as normal, fibrous or calcified. Dissection was defined as a disruption and separation of components of the arterial wall. The length and depth of arterial dissection were evaluated grossly and microscopically. RESULTS. Of the 41 arteries studied, 36 (88%) exhibited dissection on pathologic examination after balloon angioplasty. Three-dimensional reconstruction of intravascular ultrasound images identified dissection in 11 (92%) of 12 normal, 8 (100%) of 8 fibrous and 11 (69%) of 16 calcified arteries. Excellent agreement between ultrasound and pathologic findings was achieved in the evaluation of length and depth of dissection for histologically normal and fibrous arteries (kappa = 0.72 to 1.0). When the vessels were severely calcified, the agreement was not as good (kappa = 0.27 to 0.56), particularly in detection of small, non-raised intimal flaps. CONCLUSIONS. This histopathologic validation study suggests that three-dimensional intravascular ultrasound imaging facilitates the evaluation of both quantitative and morphologic features of arterial dissection induced by balloon angioplasty. The advantage of three-dimensional intravascular ultrasound is its ability to assess the length and morphology of arterial injury over an entire vessel segment.     

Update on Interventions in Renal Artery Stenosis

Noninvasive techniques such as ultrasound and renal scanning have improved the frequency of detection of renal artery stenosis in patients with arterial hypertension, renal insufficiency, or multivascular disease. The results of conventional balloon angioplasty on nonostial renal artery stenoses caused by fibromuscular dysplasia or atherosclerosis showed a high recurrence rate and a moderate impact on the management of hypertension. In patients with ostial lesions, the results of angioplasty were disappointing with low initial success rates and a high rate of restenosis. Other limitations of balloon angioplasty include initial failure or suboptimal result, occluding dissection, and short- or mid-term restenosis. The immediate procedural results of renal artery stenting are excellent, with a low complication rate and satisfactory restenosis rate. Long-term effects on renal function and blood pressure seem to be good. Systematic stent placement is indicated for ostial stenosis. For nonostial lesions, the indication for stent placement may be reserved for residual stenosis or dissection. The indication for a stent would probably be more liberal in cases of bilateral lesions or lesions in a solitary kidney. Multicenter studies probably will be needed to assess the indications and benefits obtained in different clinical and anatomical situations.