Early results of endovascular treatment of chronic coronary occlusion in patients with ischemic heart disease

The early results of endovascular treatment of chronic coronary occlusion were studied. Immediate success rates were 67%. The factors that promote successful endovascular treatment in patients with this condition were as follows: less than 2-month disease duration, well-developed intersystemic collaterals, no "bridge" collaterals. Successful recanalization for chronic coronary occlusion improves the quality of life and bicycle ergometer test finding in patients, which reduces their needs of nitrates and beta-blockers. Coronary occlusion stenting yields better immediate angiographic results than does balloon angioplasty: residual stenosis and the minimum diameter of stenosis after stenting were 13.61 +/- 6.3% and 2.69 +/- 0.4 mm, respectively; those after balloon angioplasty were 23.1 +/- 8.1% and 2.31 +/- 0.37 mm, respectively.     

The nucleotide analogue 3-deazaadenosine prevents neointima-formation after balloon injury

We have recently shown that 3-deazaadenosine (c3Ado) inhibits atherogenesis in mice. We studied whether its anti-inflammatory capacity would also affect neointima-formation after balloon injury. Sprague Dawley rats underwent balloon angioplasty. C3Ado was administered orally, starting 5 days prior to the balloon injury and continued for 2 weeks. Fourteen days after balloon injury the intima/media ratio in the c3Ado-treated group was reduced by 67% (p < 0.001) and luminal stenosis by 50% (p < 0.001). Neointimal cellular density was decreased by 25% (p < 0.001) and the induction of c-Jun and ki67 was markedly lower. The reduction of the intima/media ratio was still observed 3 months after balloon injury. Furthermore, a c3Ado-dependent inhibition of PDGF-mediated ERK-activation and proliferation could be demonstrated.Short-term administration of C3Ado inhibits neointima-formation in rats for at least 3 months after injury. The present findings implicate that c3Ado may be useful as an inhibitor of restenosis-formation after balloon angioplasty in humans.     

YC-1, a benzyl indazole derivative, stimulates vascular cGMP and inhibits neointima formation

The pathobiologic process of arterial stenosis following balloon angioplasty continues to be an enigmatic problem in clinical settings. This research project investigates the ability of YC-1, a benzyl indazole derivative that sensitizes sGC/cGMP, to stimulate endogenous cGMP and attenuate balloon injury-induced neointima (NI) formation in the rat carotid artery. Northern and Western blot analyses revealed enhanced acute expression of iNOS and inducible heme oxygenase (HO-1) mRNA and protein in the injured artery. The contralateral uninjured artery also demonstrated acute HO-1 mRNA and protein induction without detectable iNOS expression. Perivascular application of YC-1 immediately following injury significantly stimulated acute vessel wall cGMP compared to untreated controls. YC-1 treated sections demonstrated significant reduction in NI area (-74%), NI area/medial wall area (-72%), and NI thickness (-76%) 2 weeks post-injury. These results directly implicate YC-1 as a potent new therapeutic agent capable of reducing post-angioplasty stenosis through endogenous CO- and/or NO-mediated, cGMP-dependent processes.     

Catheter obstruction effect on pulsatile flow rate--pressure drop during coronary angioplasty.

The coupling of computational hemodynamics to measured translesional mean pressure gradients with an angioplasty catheter in human coronary stenoses was evaluated. A narrowed flow cross section with the catheter present effectively introduced a tighter stenosis than the enlarged residual stenoses after balloon angioplasty; thus elevating the pressure gradient and reducing blood flow during the measurements. For resting conditions with the catheter present, flow was believed to be about 40 percent of normal basal flow in the absence of the catheter, and for hyperemia, about 20 percent of elevated flow in the patient group. The computations indicated that the velocity field was viscous dominated and quasi-steady with negligible phase lag in the delta p(t)-u(t) relation during the cardiac cycle at the lower hydraulic Reynolds numbers and frequency parameter. Hemodynamic interactions with smaller catheter-based pressure sensors evolving in clinical use require subsequent study since artifactually elevated translesional pressure gradients can occur during measurements with current angioplasty catheters.     

Late color duplex scanning diagnosis of the areas of endovascular intervention into arteries and lower extremity shunts

The purpose of the study was to assess the areas of balloon angioplasty (BAP) and stenting of lower extremity arteries and femoral, popliteal, mainly, in situ autovenous shunts, by using color duplex scanning (CDS) in the late period of a follow-up. Materials and methods. The CDS technique could diagnose 344 (64%) areas of BAP and stenting of lower extremity arteries and shunts. The echosemiotics of complications typical of a late period was determined. Based on the specified echosemiotics of late complications, the author detected 99 (28.8%) cases of hemodynamically significant complications: BAP and stenting area stenosis (n=25 (7.3%)); BAP area restenosis (reocciusion) (n=33 (9.6%)); stent restenosis (n=19 (5.5%), arterial stenosis proximal and distal to a stent (n=17 4.9%)), and stent breakage (n=5 (1.5%)). Hemodynamically insignificant complications were revealed in 90 (26.2%) cases: intimal dissection in 16 (4.7%) cases, BAP area restenosis in 35 (10%), stent restenosis in 15 (4.4%), and arterial stenosis proximal or distal to the stent and between the stents. In the late period following BAP and stenting aortoiliac patency was 87.50 + 3.18% during a mean follow-up o 27.58 + 1.50 months. In the late period, the patency of the superficial femoral artery (SFR) was 55.41 + 14.43% during a mean follow-up of 22.60 + 2.73 months, that of the popliteal artery (PA) was 67.34 + 15.98% during a mean follow-up of 43.08 + 5.81 months, that of shin arteries was 44.96 + 19.77% during a mean follow-up of 18.76 + 2.58 months, and that of shunts, was 40.89 + 18.47% during a mean follow-up of 23.32 + 2.29 months. Thus, changes caused by the progression of the underlying disease--atherosclerosis were found in the areas of BAP and stenting of lower extremity arteries and shunts. Stent breakage may be due to "metal deterioration" and the presence of a stent in the superficial femoral artery with greatest functional load on extremity movement and flexion. The blood flow spectrum mode recording a local hemodynamic shift with > 2.0-2.5-fold linear blood flow velocity increase in the complication area was leading in the operation of an ultrasound apparatuses in the differential diagnosis of hemodynamically significant and insignificant complications. The results of good late patency of the areas of BAP and stentming of SFR and PA may be accounted for by strict criteria for selecting patients for endovascular surgery, by taking into account the indications for and contraindications to TASC (2001). In our study, 20 endovascular reinterventions (repeated balloon angioplasty, additional stenting stent balloon angioplasty) in complicated areas were performed, which maintained and prolonged the function of segments. The detection of hemodynamically insignificant complications revealed patients who need further meticulous follow-up ultrasound studies.     

Telomeric restriction analysis of vascular smooth muscle cells following balloon angioplasty in rabbits

Intimal hyperplasia due to smooth muscle cell proliferation and migration has been reported to be responsible for the pathogenesis of atherosclerosis and restenosis, manifested following balloon angioplasty. In this study, we employed the balloon angioplasty model to study telomere length regulation in proliferating vascular smooth muscle cells. Our results showed that balloon angioplasty in iliac arteries resulted in intimal hyperplasia due to proliferation of the smooth muscle cells and small size telomeric restrictional fragments were evident in injured arteries.     

Acute coronary syndrome during pregnancy

Two cases of myocardial infarction during the second trimester of pregnancy are presented. Both patients were treated with thrombolytic therapy. In the first case the treatment was successful, in the other patient thrombolysis only temporarily relieved the symptoms. Therefore, angiography was performed and a significant stenosis in the left anterior descending coronary artery was successfully treated with balloon angioplasty. Both women delivered a healthy child, the first child was born at term, the second at a gestational age of 33 weeks. Percutaneous intervention versus thrombolytic therapy in pregnancy is discussed.     

An introduction to provisional stenting

Provisional or conditional stenting should be defined as the use of stents limited to those conditions and cases in which the operator, despite an aggressive balloon angioplasty technique with large balloons and high pressure, has been unable to obtain a result that ensures optimal chances of early and late patency. The paramount issue is how to discriminate the patients with optimal results after balloon angioplasty for whom additional stent implantation is unlikely to improve or may even worsen long-term outcome. The better results of elective stent implantation in the OPUS study suggest that visual assessment of the PTCA result is not sufficient to detect lesions with suboptimal lumen gain after PTCA. The addition of physiologic parameters (Doppler flow velocity measurements, fractional flow reserve) has improved the results of the provisional stent group, with the best outcome observed when complex lesions and multivessel treatment were included in these studies (FROST, DESTINI). Intravascular ultrasound, although more expensive and time-consuming, has the additional advantage to guide the dilatation strategy.     

Rat carotid artery dilation by PTCA balloon catheter induces neointima formation in presence of IEL rupture

The best animal angioplasty model is the porcine model, which is expensive and not available in all laboratories. The aim of this study was to describe a new rat model of angioplasty. An injury was induced with the use of a standard percutaneous transluminal coronary angioplasty (PTCA) 1.5-mm balloon catheter. The neointimal tissue, arterial dimensions, and the injury index were assessed following angioplasty. Ki-67 expression was detected to evaluate cell turnover after balloon angioplasty. In contrast with the standard Clowes model, a significant neointimal formation was detected only in the presence of ruptured internal elastic lamina (IEL). A positive correlation between the percentage of ruptured IEL and the amount of neointimal tissue was also demonstrated. The percentage of IEL fracture correlates with the proliferation index by anti-Ki-67 immunolabeling 7 and 14 days after the angioplasty. Significant arterial negative remodeling was observed following PTCA balloon dilation. In conclusion, our inexpensive animal model of restenosis after angioplasty may have great relevance toward a better understanding of the mechanisms and toward assessment of new therapeutical strategies for this phenomenon.     

Analysis of the transient expansion behavior and design optimization of coronary stents by finite element method

The percutaneous transluminal coronary angioplasty (PTCA) assisted with stenting technique has become a primary therapy to coronary heart disease. In practice, the structure conditions of both ends of stent/balloon system influence a stent's instantaneous expansion behavior. The transitory nonuniform expansion, the so-called dogboning, of stent/balloon system is one of the main reasons to induce the acute vascular injury at the two edges of a stent. This kind of vascular injury has a close relationship with the in-stent restenosis. In the present paper, the finite element method (FEM) was applied to simulate the transient expansion process of stent/balloon system with different stent structure and balloon length under the internal pressure. And two types of stent and six collocations of stent and balloon were modeled. Modeling results showed that the dogboning phenomenon can be eliminated by improving geometry of a stent or/and varying the length of balloon over stent. The above modeled results were further confirmed by following in situ observation.     

Plasma endothelin levels as a function of coronary artery manipulation during balloon angioplasty and high-speed rotational atherectomy

This study was conducted to test the hypothesis that endothelin levels may be related to the coronary artery manipulation during balloon angioplasty (BA) or rotational atherectomy (RA). Blood endothelin levels were measured in 35 patients who underwent BA and in 11 patients who underwent RA followed by adjunctive balloon angioplasty. Arterial and venous levels were measured before, immediately after, and 24 h after the procedure. The levels were then related to the number of balloon inflations, the total inflation time and the maximal pressure in the balloon during inflation. There were no significant differences between groups or time periods. However, 24 h after BA the endothelin plasma levels in venous blood were directly related to the number of balloon inflations (r 3 0.49; P 3 0.03), to the total inflation time (r 3 0.67; P 3 0.005) and to the maximal inflation pressure (r 3 0.71; P 3 0.001). No such correlation was found in venous blood immediately after BA, either in arterial blood or in the RA group. It can be concluded that plasma endothelin levels do not change significantly after balloon angioplasty; however, venous endothelin levels 24 h after BA are related to procedural parameters, reflecting endothelial damage, which may determine the post-angioplasty late results.     

Provisional stenting in the real world: results in 1058 consecutive patients undergoing percutaneous coronary angioplasty

OBJECTIVE: To study a strategy of aggressive coronary balloon angioplasty with provisional stenting in allcomers. In randomized trials, stenting has improved the outcome of patients undergoing coronary intervention. However, whether these results hold up in clinical practice is largely unknown. Furthermore, the results of balloon angioplasty have also improved dramatically. It is therefore essential to evaluate the current results of balloon angioplasty and to assess whether stents are required in all patients. METHODS: The authors prospectively studied the occurrence of death, myocardial infarction (MI) and target lesion revascularization (TLR) of a large consecutive group of patients undergoing aggressive balloon angioplasty with provisional stenting. None of the patients received a platelet glycoprotein IIb/IIIa receptor blocker. The results were compared with the outcome of routine stenting in recent randomized trials. RESULTS: Angioplasty was performed in 1058 patients of whom 369 (34.9%) received a stent. The angiographic success rate was 98.9%. During hospital stay, 4.8% of the patients suffered any cardiac event. At one-year follow-up, death occurred in 1.1%, MI in 3.3%, TLR in 12.4% and any event in 16.7% of the patients. Event-free survival at one-year was 82.3%. These results compare favorably with routine stenting in recent trials. CONCLUSIONS: Aggressive balloon angioplasty with provisional stenting yields excellent results in a general patient population.     

Ultrasound guidance: technique and results of aggressive ultrasound-guided PTCA. The UPSIZE Pilot Trial

Stenting results in a larger lumen than conventional balloon angioplasty. This is the major determinant of a good acute and long-term result. In this non-randomised, single centre trial, intravascular ultrasound was used preinterventionally to guide the choice of the balloon size. The aim was to achieve a maximum lumen area with balloon angioplasty only. We included 346 patients with 360 lesions. The diameter of the external elastic lamina by intravascular ultrasound was 4.67 mm. A mean balloon size of 4.0 mm was chosen. The initial luminal gain was 1.82 mm, the lumen area post intervention was 6.6 mm(2). Dissections occurred frequently but the incidence of major adverse events was not increased. At one year follow-up, the overall event free survival was 81%. Target lesion revascularisation was performed in 34 patients (10%). An angiographic follow-up was available for 261 patients (76%). Restenosis (> 50% diameter Stenosis) was found in 21%. The results show, that ultrasound guidance of balloon angioplasty provides a means to achieve a large initial luminal gain without the routine use of stents. The acute and long-term results suggest that the approach is safe and efficient. The data compare favorably with similar studies using advanced intravascular diagnostic tools to guide the angioplasty procedure.     

Comparison of the results of stenting ans balloon angioplasty of coronary arteries in relation to the type of stenosis

Based on the comparison of the immediate and late results of stenting and balloon angioplasty (BA), the authors consider whether it is expedient to perform stenting of coronary arteries (CA) in all cases of BA in patients with coronary heart disease (CHD) and different types of CA stenosis. The study included 410 patients: a group of stenting (n = 197) and a group of traditional BA (n = 213). All the patients in both groups were divided into four subgroups in relation to the type of detected stenosis according to the classification of the American Association of Cardiologists (ACC/AHA). The positive angiographic and clinical results were observed in all 197 patients after stenting. This was associated neither with the type of dilated stenosis nor with the design of an implanted stent. In dilation of types A and B1 stenoses, a stent-like result was significantly more frequently observed than in dilation of types B2 and C stenoses. There was no significant difference in the development of restenosis in patients after routine BA and stenting of types A and B1 stenoses. At the same time, after BA of types B2 and C stenoses, restenosis developed significantly more frequently than in stenting. Thus, on the basis of this study, it may be stated that the traditional BA yields the so-called stent-like result significantly more frequently in patients with uncomplicated forms of CA stenoses than in those with complicated ones. Once the stent-like result is achieved in patients with type A stenoses, stenting should not be performed since the latter fails to improve the immediate and late results of angioplasty. Despite that the stent-like result is achieved in patients with complicated forms of CA stenoses, it is expedient to make stenting. Our findings indicate that the obtained good immediate result reduces the incidence of restenosis.     

Long period of balloon inflation and the implantation of stents potentiate smooth muscle cell death. Possible role of chronic vascular injury in restenosis

BACKGROUND: It has been suggested that the severity of acute vascular injury immediately after percutaneous transluminal coronary angioplasty (PTCA) or stent implantation correlates with the extent of neointimal hyperplasia and restenosis. However, the influence of prolonged or chronic vessel injury on the pathogenesis of restenosis is unclear. METHODS: Rabbit iliac arteries were balloon dilated for a short (1 min) or prolonged (10 min) period of time, or were chronically dilated and received a Palmaz-Schatz stent (balloon inflation for 1 min). All arteries were overexpanded to a balloon:artery ratio of 1.2:1 as determined by angiography. The arteries were removed 30 min and 4 weeks after the angioplasty procedures. The sites of injury were evaluated by gross histology and transmission electron microscopy (TEM). Cell death of medial smooth muscle cells (SMCs) was specified by TEM images 30 min after the procedures. Computer-assisted quantification of the neointimal cross-sectional areas was performed after 4 weeks using a light microscope connected to a digital image analyser. RESULTS: The results show that prolonged balloon dilatation and stent implantation increased necrotic SMC death compared with balloon dilatation for 1 min. After 30 min, increased staining of SMC nuclei, enlarged intercellular spaces and changes in SMC shape in the media indicated cell death induced by prolonged balloon dilatation or chronic stent injury. Stent implantation markedly augmented vessel damage by persistent compression of the media, compared with a balloon dilatation for 1 or 10 min. Both prolonged balloon dilatation and stent implantation increased neointimal hyperplasia at 4 weeks compared with balloon dilatation for 1 min (0.6 3 0.2 and 1.0 3 0.2 mm(2) versus 0.2 3 0.1 mm(2), P < 0.001 versus dilatation for 1 min). CONCLUSION: Prolonged or chronic vascular expansion due to long balloon-inflation periods or the implantation of stents increases medial SMC death, which subsequently stimulates neointimal growth in this restenosis model. Chronic vascular injury may be an important stimulus for restenosis after angioplasty procedures.     

Safety and efficacy of treatment with platelet GPIIb/IIIa receptor blockade in unstable angina patients awaiting PTCA at a referring clinic

BACKGROUND: Although balloon angioplasty has assumed an important role in the management of refractory unstable angina (UA), that is, UA that does not respond to conventional therapy, it is limited by complications related to thrombosis and acute coronary occlusion. The complication rate is higher in patients with UA than in those whose condition is stable. Preprocedural use of abciximab, a monoclonal platelet glycoprotein IIb/IIIa receptor blocker, has been used effectively in patients with UA, but its acceptance may be limited by safety concerns and economic constraints. The current trial investigated a protocol for abciximab pretreatment in patients with UA awaiting transfer from referring hospitals to a site of intervention (the 'drip and ship' protocol). AIMS: This observational study was conducted to evaluate whether a prophylactic, preprocedural regimen of abciximab can be safely and effectively administered to UA patients in referring hospitals while awaiting coronary angioplasty at the interventional clinic. METHODS: From April 1996 to December 1998, 168 consecutive patients with refractory UA (Braunwald class II or III) received abciximab prospectively at the referring clinic before undergoing PTCA or stent implantation at the interventional clinic. The following cost-conscious protocol was used: a 0.25 mg/kg bolus of abciximab followed by 10 micro g/min intravenously for 16 hours, in addition to intravenous nitrates, heparin and aspirin therapy. Patients were then transferred to a facility with PTCA capability via high-speed ambulance transport. No specific alterations of routine-transfer protocol were needed. Platelet aggregation studies were conducted during abciximab infusion. All interventions were performed while abciximab was given. Procedural and clinical success and long-term outcomes also were assessed. RESULTS: The primary angiographic success rate (patients with post-PTCA diameter stenosis < 50%) was 98%, and the in-hospital clinical success rate (angiographic success without major complications) was 98%. No major bleeding complications occurred during the abciximab pretreatment period. Platelet aggregation findings in the study patients showed a stable inhibition of >80% at the time of angioplasty. At 30-day follow-up, all patients were alive and 91% were free of major adverse events. Outcomes of balloon angioplasty and stenting were equally favorable, indicating no device-specific effect. Event-free survival at six months was 89% with a target vessel revascularization rate of 10%. CONCLUSION: Abciximab was administered safely and effectively to angioplasty patients with refractory UA awaiting transfer from a noninterventional setting to the site of angioplasty. These results extend the current knowledge base that has been established in randomized trials performed in interventional centers. The study protocol potentially could make abciximab therapy more feasible economically, and therefore more widely available to patients who are most likely to benefit from prophylactic administration.     

Changes in the mechanical environment of stenotic arteries during interaction with stents: computational assessment of parametric stent designs

Clinical studies have identified factors such as the stent design and the deployment technique that are one cause for the success or failure of angioplasty treatments. In addition, the success rate may also depend on the stenosis type. Hence, for a particular stenotic artery, the optimal intervention can only be identified by studying the influence of factors such as stent type, strut thickness, geometry of the stent cell, and stent-artery radial mismatch with the wall. We propose a methodology that allows a set of stent parameters to be varied, with the aim of evaluating the difference in the mechanical environment within the wall before and after angioplasty with stenting. Novel scalar quantities attempt to characterize the wall changes inform of the contact pressure caused by the stent struts, and the stresses within the individual components of the wall caused by the stent. These quantities are derived numerically and serve as indicators, which allow the determination of the correct size and type of the stent for each individual stenosis. In addition, the luminal change due to angioplasty may be computed as well. The methodology is demonstrated by using a full three-dimensional geometrical model of a postmortem specimen of a human iliac artery with a stenosis using imaging data. To describe the material behavior of the artery, we considered mechanical data of eight different vascular tissues, which formed the stenosis. The constitutive models for the tissue components capture the typical anisotropic, nonlinear and dissipative characteristics under supra-physiological loading conditions. Three-dimensional stent models were parametrized in such a way as to enable new designs to be generated simply with regard to variations in their geometric structure. For the three-dimensional stent-artery interaction we use a contact algorithm based on smooth contact surfaces of at least C-continuity, which prevents numerical problems known from standard facet-based contact algorithm. The proposed methodology has the potential to provide a scientific basis for optimizing treatment procedures and stent geometries and materials, to help stent designers examine new stent designs "virtually," and to assist clinicians in choosing the most suitable stent for a particular stenosis.     

经隐动脉建立糖尿病兔股动脉血管狭窄模型

目的探讨建立糖尿病兔股动脉损伤后血管狭窄的模型方法。方法采用四氧嘧啶静脉注射建立糖尿病兔模型。建模成功后分为手术组、对照组,手术组接受了经隐动脉途径行球囊损伤股动脉术,对照组不行球囊损伤。术后均给予普食喂养,4周处死,行HE染色后观察血管狭窄情况。结果所有兔均完成了手术,24只存活至实验结束,平均手术时间（26±7）min,成功造成糖尿病兔股动脉狭窄模型,平均相关狭窄达（88.11±1.9）%。结论成功建立了糖尿病兔股动脉损伤后狭窄的实验模型,手术成功率高,操作时间少,存活率高,模型稳定,重复性好,为糖尿病外周血管病变的实验研究提供了借鉴方法。     

Interventional radiology in congenital and acquired cardiovascular diseases

The paper outlines the present-day achievements in interventional radiology in cardiovascular diseases: balloon valvuloplasty in cardiac diseases (isolated pulmonary arterial stenosis, aortic and mitral stenosis), balloon vasodilatation (peripheral pulmonary arterial stenosis, aortic coarctation), embolization of the vessels and pathological communications, atrioseptostomy, transcatheter closure of atrial septal defects.