Limited balloon expansion through the struts of the Palmaz-Schatz and NIR stents compared with the Multi-Link stent

After placing a stent in the main vessel of a bifurcation lesion, it is sometimes necessary to perform further balloon inflation in order to treat an ostial lesion in a side branch. The stent struts may prevent full balloon expansion at the ostium of a side branch, resulting in residual ostial stenosis. The degree of completeness of balloon inflation may vary significantly depending on the stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the side branch were both 3.5 mm. Deployment of the Palmaz-Schatz stent (n=5), NIR stent (n=5) or Multi-Link stent (n=5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 12 atm. A 3.5-mm balloon catheter was then inflated to 12 atm through the stent struts of the main vessel and into the ostium of the side branch. The degree of completeness of balloon inflation (% balloon expansion) was calculated as (smallest diameter of balloon catheter/reference diameter of balloon catheter) x 100%. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch created with the stent struts were also measured. Limited balloon expansion through the struts was observed with the Palmaz-Schatz stent and the NIR stent, but almost full balloon expansion was observed with the Multi-Link stent (% balloon expansion: Palmaz-Schatz stent 80%, NIR stent 60%, Multi-Link stent 94%, p<0.01). The MLD and CSA of the dilated struts, representing the ostium of the side branch, of the Palmaz-Schatz stent (2.2+/-0.1 mm, 4.5+/-0.3 mm2) and the NIR stent (1.8+/-0.1 mm, 3.1+/-0.3 mm2) were significantly smaller compared with those of the Multi-Link stent (3.0+/-0.2 mm, 8.4+/-0.6 mm2) (p<0.01). The struts of the Palmaz-Schatz stent and the NIR stent deployed in the main vessel of a bifurcation prevent full expansion of a balloon catheter inflated at the side branch ostium. In contrast, almost full balloon expansion through the struts of the Multi-Link stent is achieved.     

Influence of expanded balloon diameter on palmaz-schatz stent recoil

After successful stent implantation, the residual luminal diameter of the stented vessel is usually smaller than the maximal stent-expanded balloon diameter. The goal of this study was to determine whether immediate vessel diameter recoil after Palmaz-Schatz stenting is affected by the final expanding balloon diameter used during stent deployment. Single Palmaz-Schatz balloon expandable stents were successfully placed in 108 stenotic lesions. There were 68 patients with 75 saphenous vein graft (SVG) and 30 patients with 33 native coronary artery lesions, including 26 restenotic and 82 de novo occlusive (>50% diameter stenosis) lesions. Quantitative coronary angiography was used for the assessment of stent recoil, defined as the difference between the minimal diameter of the fully expanded balloon and the postprocedure minimal lumen diameter divided by minimal diameter of the fully expanded balloon. A strong correlation (r = 0.94) was found between the minimal diameter of the fully expanded balloon and poststenting minimal lumen diameter. Immediate recoil was 11.3 ± 7.5%, responsible on an average for 0.4 ± 0.2-mm acute lumen loss. Recoil was less in SVG than in coronary arteries (9.7 ± 6.6% vs. 14.0 ± 7.8%; P = 0.004, and 0.3 ± 0.2 vs. 0.4 ± 0.2 mm; p = 0.01). Lesions were divided into four subgroups, based on the final stent expanding balloon diameter: (1) ?3.0 mm (n = 33); (2) >3 ± 3.5 mm (n = 43); (3) >3.5 ± 4 mm (n = 23); and (4) >4 mm (n = 9). For the four subgroups, the percentage recoil values were 15.0 ± 5.7, 10.4 ± 8.2, 9.0 ± 5.4, and 4.7 ± 2.0, respectively (P <0.001). Mean values of diameter stenosis, lesion length, maximal balloon pressure, balloon-to-artery ratio, relative vessel stretch, and absolute recoil were not statistically different. Immediate vascular recoil in single implanted Palmaz-Schatz stent is a function of the final expanding balloon diameter, with recoil larger at small-balloon diameters and almost eliminated at large inflation diameters. This finding could contribute to less acute gain, increased restenosis, and higher stent thrombosis rates after stenting vessels of <3-mm diameter. © 1995 Wiley-Liss, Inc.     

Effect of balloon inflation time on expansion of sirolimus-eluting stent

There is little information about the relationship between balloon inflation time and sirolimus-eluting stent (SES) expansion. In this randomized intravascular ultrasound (IVUS) study, 92 de novo lesions in native coronary arteries that underwent SES implantation were enrolled. Sirolimus-eluting stent was implanted using an inflation pressure of 14 atm. Stent balloon was gradually inflated until 14 atm in 10 s. In the short inflation group, it was deflated immediately after an image of the balloon inflated at 14 atm was taken. Stent balloon inflation lasted 60 s in the long inflation group. Intravascular ultrasound was then performed. The long balloon inflation resulted in a larger stent cross-sectional area (4.9 ± 1.6 mm² vs 4.3 ± 1.4 mm², P < 0.05) and expansion (71% ± 13% vs 60% ± 13%, P < 0.001) compared to the short balloon inflation, although stent expansion was relatively low in both groups. The relatively longer balloon inflation time using an inflation pressure of 14 atm results in better SES expansion. However, in the majority of lesions, adequate stent expansion is not achieved even using long balloon inflation, if it is inflated at 14 atm.     

Underexpansion of sirolimus-eluting stents: incidence and relationship to delivery pressure.

We aimed to assess the incidence of underexpansion and the relationship between delivery pressure and expansion with sirolimus-eluting stents. Adequate stent expansion contributes to early and late improved outcomes. In 51 patients (53 lesions) with native coronary artery narrowing, balloon-expandable sirolimus-eluting stents (Cypher) were serially expanded with gradual balloon inflations [14 atm, 20 atm, and in case of minimal stent cross-sectional area (CSA)/reference lumen CSA < 50% at 20 atm, postdilatation with 0.5 mm larger balloon]. Intravascular ultrasound (IVUS) imaging was performed before intervention and after each gradual balloon inflation. Stent expansion (minimal stent CSA/reference lumen CSA) was measured. Stent expansion was 72% +/- 16% after 14 atm balloon inflation, 90% +/- 18% after 20 atm balloon inflation (P < 0.001 vs. 14 atm), and 90% +/- 18% at the end of the procedure (including optional postdilatations with 0.5 mm larger balloon; P = NS vs. 20 atm). Stent expansion addressed by MUSIC criteria (all struts apposed, no tissue protrusion, and final lumen CSA > 80% of the reference or > 90% if minimal lumen CSA was < 9 mm2) was adequate in 15% of the cases after 14 atm balloon inflation, in 60% after 20 atm balloon inflation (P < 0.001 vs. 14 atm), and in 60% at the end of the procedure (P = NS vs. 20 atm). Sirolimus-eluting stent underexpansion is common when deployed at conventional pressures. Increasing balloon delivery pressure or assessing stent expansion with IVUS seems warranted in order to ensure adequate sirolimus-eluting stent deployment.     

The role of elastic recoil after balloon angioplasty of rabbit arteries and its prevention by stent implantation

Elastic recoil, neointima formation and vessel narrowing afterballoon angioplasty or stent implantation were compared in 17non-atherosclerotic New Zealand White rabbits. The implantationof a balloon-expandable Palmaz-Schatz stent was performed inone iliac artery and a balloon angioplasty alone was performedin the contralateral artery (n=34 arteries). Quantitative histomorphometrywas performed by a computer-assisted analysis 1 h and 4, 10and 24 weeks after the initial procedure. The histological appearanceof the neointima was similar to that of human restenosis. Theamount of the neointima was increased within sten ted vesselsas compared to balloon angioplasty alone (1·0±0·1vs 0·4±0·1 mm² at 4 weeks, P<0·001).However, the neointimal lumen narrowing was smaller in the stentedvessels due to persistent increase in vessel perimeter as comparedto balloon angio plasty alone (16·5±0·9vs 34·7±16·5% lumen narrowing at 4 weeks,P<0·05). In conclusion, stent implantation enhancesneointima formation as compared to angioplasty in non-atheroscleroticrabbits. The prevention of elastic recoil after stent implantation,however, reduces the neointimal lumen narrowing. This studysupports clinical observations demonstrating lower restenosisrates after stent implantation compared to standard balloonangioplasty.     

New stent delivery balloon: A technical note

This study reports the first clinical application of a new noncompliant balloon composed of a middle polyurethane layer sandwiched between an inner layer of polyethylene terephtalate and an outer membrane that provides for consistent even expansion. With this balloon design, the very low compliance and high pressure resistance of polyethylene terephthalate are associated with the high elasticity of polyurethane, preventing balloon damage from stent crimping and expansion and allowing a firm embedding of the stent struts. Palmaz-Schatz stent implantation was successful in 33/35 stents (94%), and the two stents that could not be advanced up to the lesion were successfully withdrawn. High pressure expansion of the stent was obtained during deployment with no balloon ruptures at inflation pressures equal or lower than 16 atmospheres (atm). Accurate positioning of the stent was facilitated by the two markers at the balloon ends and by the optimal visualization after contrast injection, even with 6 Fr guiding catheters. This new delivery system maintains the advantages of hand-crimped stents on noncompliant balloons, reducing the risk of stent loss. Cathet Cardiovasc. Diagn. 42:452–456, 1997. © 1997 Wiley-Liss, Inc.     

Intracoronary stent implantation using a single high-pressure perfusion balloon catheter

Currently, the recommended strategy for Palmaz-Schatz intracoronary stent implantation is to use two balloons: an undersized balloon for predilation to facilitate a channel for the stent and a high pressure balloon for postdilation to obtain good apposition of the struts into the vessel wall. We reported our experience using the perfusion balloon as the initial balloon to dilate intracoronary lesions and demonstrated a reduction in the total number of balloons used per angioplasty procedure. The objective of this study was to examine whether a single balloon could effectively be used for stent implantation. The study population included 95 patients who underwent elective intracoronary stent placement to 100 lesions using 110 Palmaz-Schatz stents by nine individual operators. Lesions were predilated with an ACS RX LIFESTREAM balloon at a low pressure of 4–6 atm (mean 5.7 ± 2.6). After stent deployment, the same balloon was used at a high pressure (mean 16.2 ± 1.2). Mean balloon size, which was chosen as the stent size, was 3.4 ± 0.4 mm. Comparison of this strategy with the recommended strategy of 68 consecutive elective stent deployments at a single center during the same time was performed. Stent implantation using a single balloon strategy was angiographically successful in 99 of 100 (99.0%) lesions. The single balloon strategy was associated with a balloon burst rate of 9.1%. The number of balloons used per stent deployment was 1.2 vs. 2.4 using the recommended strategy (P < 0.0001). There was no evidence of stent thrombosis, any MI, or target lesion revascularization during the procedure and hospitalization. One in-hospital death as a result of nonhemorragic stroke was documented in the treated group. We concluded that using a single high pressure perfusion balloon for pre and postdilation in patients undergoing elective stent placement is safe and reduces the number of balloons used per procedure. Cathet. Cardiovasc. Diagn. 40:140–143, 1997. © 1997 Wiley-Liss, Inc.     

Benefits of cutting balloon before stenting

The objectives of this study were to prospectively evaluate the safety and feasibility of pretreating the culprit coronary artery lesion with cutting balloon (CB) angioplasty prior to coronary stent implantation. BACKGROUND: The CB has shown promise for the treatment of de novo coronary lesions and in-stent restenoses, but has not been prospectively evaluated for use prior to stent implantation. METHODS: Patients with significant coronary artery disease requiring stent placement had the culprit lesion pretreated with a CB. Stents were deployed to cover the entire segment pretreated with the CB. Intravascular ultrasound (IVUS) was used to interrogate acute luminal gain following stent implantation and after serial post-deployment inflation pressures ranging from 8 16 atmospheres (atm). Coronary angiograms were also obtained to determine luminal diameter. In-hospital complication rates were noted. RESULTS: Fifty-one patients were treated with the CB prior to stent implantation. Minimal stent cross-sectional area increased significantly with increasing inflation pressures between 8 and 10 atm (p < 0.0004) and between 10 and 12 atm (p = 0.0049). The minimal stent cross-sectional area achieved, as measured by IVUS, was 7.59 mm2 2.00 mm2 at 8 atm, 8.06 mm2 1.53 mm2 at 10 atm and 8.72 mm2 1.58 mm2 at 12 atm. The final in-stent percent diameter stenosis was lower compared to pre-procedure (5.4% 12.2% versus 64.1% 14.1%, respectively) by quantitative coronary angiography. CONCLUSION: The CB can be used prior to stent implantation to attain significant gains in minimal stent cross-sectional areas at relatively low pressures.     

Safety and Efficacy of Angiographic Guided Elective Palmaz-Schatz Stent Implantation Without Coumadin: Comparison of Stent Implantation and Angioplasty

This study was designed to evaluate the safety and efficacy of routine high-pressure Palmaz-Schatz coronary stenting in patients with symptomatic coronary heart disease with only angiographic guidance without coumadin for poststenting treatment. Intracoronary stenting reduces restenosis rate after coronary angioplasty. High pressure stent deployment with intravascular ultrasound guidance reduces the incidence of stent thrombosis, despite reduction of anticoagulation. However, the feasibility of routine stent implantation with only angiographic guidance and without coumadin for poststenting treatment has not yet been determined. Patients undergoing coronary angioplasty for symptomatic coronary heart disease received stent implantation for abrupt or threatening vessel occlusion, vessel dissection without compromised antegrade blood flow (but at high risk for subacute occlusion and early restenosis), unsatisfactory angioplasty result with > 30% residual stenosis, and elective stent implantation in de novo lesions, restenotic lesions, and lesions in bypass grafts. Quantitative coronary analysis was performed before the procedure, immediately after, and at follow-up 6 ± 1 (SD) months later. This patient group was matched for clinical and angiographic characteristics with those patients who underwent balloon angioplasty during the same period. Patients who underwent coronary stenting had larger net gain (1.95 ± 1.0 vs 1.42 ± 0.9; P < 0.001) resulting in a larger minimal luminal diameter (2.48 ± 1.19 vs 1.78 ± 1.01; P < 0.001) at follow-up as compared with balloon angioplasty. Restenosis, defined as > 50% diameter stenosis at follow-up, occurred in 35.0% in the PTCA group and in 16.1% in the stent group (P < 0.001). Subacute stent thrombosis occured in one patient (0.8%) due to angiographically evident suboptimal stent expansion. Routine coronary high pressure Palmaz-Schatz stenting with angiographie guidance without coumadin for poststenting treatment represents a safe and effective option in patients with symptomatic coronary heart disease without increasing the incidence of (sub)acute stent thrombosis.     

Predictors of Restenosis After Coronary Stent Implantation

Objectives. We sought to determine predictors of restenosis after coronary stenting (CS) in a consecutive series of patients.Background. Although stenting in highly selected patient groups reduces restenosis, the results of stenting in a heterogeneous patient group and the effects of clinical and procedural factors on stent restenosis are currently unclear.Methods. We analyzed the 6-month angiographic outcome of 500 lesions in 463 consecutive patients undergoing successful CS. Clinical, qualitative and quantitative angiographic variables were correlated with restenosis assessed as both a binary and a continuous variable.Results. Restenosis, defined as the presence of >50% diameter stenosis in the dilated segment, was present in 105 (26%) of the 405 lesions with angiographic follow-up. The mean late lumen loss during the follow-up period was 0.79 ± 0.64 mm. Implantation of multiple stents (p < 0.0001) and a high acute gain (p < 0.0002) were independently associated with a higher late lumen loss. In contrast, the use of high inflation pressure (p < 0.02) and Palmaz-Schatz stents (p < 0.005) was independently associated with a lower late lumen loss. When restenosis was defined as a qualitative variable, implantation of multiple stents (p < 0.001), stenosis length (p < 0.01), small reference diameter (p < 0.02) and stent type other than Palmaz-Schatz (p < 0.01) were independent predictors of restenosis. None of the clinical variables tested was associated with restenosis.Conclusions. Coronary stenting in an unselected patient group is associated with an acceptable restenosis rate. Although some risk factors were identified, the risk of restenosis was not related to most of the variables tested. This suggests that the superiority of CS over balloon angioplasty, in terms of restenosis, might also apply to subgroups of patients that were not included in the recent randomized studies.     

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.     

Balloon angioplasty for the treatment of coronary in-stent restenosis: immediate results and 6-month angiographic recurrent restenosis rate

Objectives. The purpose of this prospective study was to evaluate the immediate results and the 6-month angiographic recurrent restenosis rate after balloon angioplasty for in-stent restenosis.Background. Despite excellent immediate and mid-term results, 20% to 30% of patients with coronary stent implantation will present an angiographic restenosis and may require additional treatment. The optimal treatment for in-stent restenosis is still unclear.Methods. Quantitative coronary angiography (QCA) analyses were performed before and after stent implantation, before and after balloon angioplasty for in-stent restenosis and on a 6-month systematic coronary angiogram to assess the recurrent angiographic restenosis rate.Results. Balloon angioplasty was performed in 52 patients presenting in-stent restenosis. In-stent restenosis was either diffuse (≥ 10 mm) inside the stent (71%) or focal (29%). Mean stent length was 16 ± 7 mm. Balloon diameter of 2.98 ± 0.37 mm and maximal inflation pressure of 10 ± 3 atm were used for balloon angioplasty. Angiographic success rate was 100% without any complication. Acute gain was lower after balloon angioplasty for in-stent restenosis than after stent implantation: 1.19 ± 0.60 mm vs. 1.75 ± 0.68 mm (p = 0.0002). At 6-month follow-up, 60% of patients were asymptomatic and no patient died. Eighteen patients (35%) had repeat target vessel revascularization. Angiographic restenosis rate was 54%. Recurrent restenosis rate was higher when in-stent restenosis was diffuse: 63% vs. 31% when focal, p = 0.046.Conclusions. Although balloon angioplasty for in-stent restenosis can be safely and successfully performed, it leads to less immediate stenosis improvement than at time of stent implantation and carries a high recurrent angiographic restenosis rate at 6 months, in particular in diffuse in-stent restenosis lesions.     

Difference in security of stent jail between Palmaz-Schatz, NIR, and Multi-Link stents: the effect of balloon inflation through stent struts.

After placing a stent in the main vessel of a bifurcation lesion, it is often necessary to perform further balloon inflation or stent placement through the stent struts in order to treat a lesion of the secondary vessel or side branch. This balloon inflation with dilatation through the cells of the stent in the main vessel results in stent strut disfigurement. This disfigurement causes various degrees of stenosis within the main vessel secondary to stent strut deformity. The degree of strut deformity, and therefore stenosis, may vary significantly depending on stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the secondary vessel were both 3.5 mm. Deployment of the Palmaz-Schatz stent (PS, n = 5), NIR stent (n = 5), or Multi-Link stent (n = 5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 6 atm. A second 3.5-mm balloon catheter was then inflated to 6 atm through the stent struts of the main vessel and into the ostium of the secondary vessel. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch and the stenosis within the main vessel were then measured, taking into account the stent deformity that occurred. Kissing balloon dilatation with two 3.5-mm balloon catheters was then performed and the stenosis secondary to stent deformity in the main vessel was remeasured. The MLD of the Multi-Link stent at the side-branch ostium was greater compared with those of the Palmaz-Schatz stent or the NIR stent (2.4 +/- 0.1, 1.6 +/- 0.1, 1.7 +/- 0.1 mm, P < 0.01) and CSA (4.9 +/- 0.5, 2.7 +/- 0.3, 2.5 +/- 0.3 mm(2), P < 0.01). Balloon inflation through the stent struts caused stent deformity that resulted in some degree of stenosis within the stent of the main vessel in all three stent types. Kissing balloon inflation reduced, but never eliminated, this stenosis. The percent stenosis in the main vessel secondary to stent deformity (PS 34% +/- 9%, NIR 25% +/- 8%, Multi-Link 34% +/- 7%, NS) and residual stenosis postkissing balloon inflation (PS 12% +/- 1%, NIR 10% +/- 3%, Multi-Link 14% +/- 3%, NS) were not significantly different among these three stents. At the side-branch ostium, the MLD and CSA were significantly greater for the Multi-Link stent compared with those of the Palmaz-Schatz or NIR stent. Balloon inflation through the stent struts caused stent deformity that resulted in stenosis within the stent in the main vessel. Kissing balloon inflation reduced this stenosis, but some residual stenosis always remained. The stenoses within the main vessel did not differ among the three stent types. Cathet. Cardiovasc. Intervent. 48:230-234, 1999.     

Should every eligible lesion undergo direct stenting?

Although significant coronary artery (CA) calcification is believed to affect stent deployment, the exact impact on stent deployment after high-pressure balloon inflations is unknown. Intracoronary intravascular examination (ICUS) was performed in 27 moderate-severe calcified CA lesions before and after stent implantation. In case of unsatisfactory results (in-stent area < 90%, minimal in-stent diameter/maximal in-stent diameter < 0.8), further inflations up to 20 atm guided by ICUS were applied. Initially, stent expansion was adequate in 10 stents (37%) and symmetric in 19 (70%). After inflation at 20 atm, stents with adequate expansion increased to 16 (59%, P = 0.0036), but stents with symmetry decreased to 13 (48%, P = 0.0045). Stent expansion was inversely correlated to the arc of calcium (r = -0.8, P < 0.0001). There were five patients with clinical restenosis at 6 months (18%). Increases in stent lumen area with high-pressure balloon inflations in moderate-severe calcified CA lesions are at the expense of symmetry. This may affect clinical restenosis.     

Comparison of paclitaxel-eluting stent and sirolimus-eluting stent expansion at incremental delivery pressures

OBJECTIVES: We sought to compare the adequacy of paclitaxel-eluting stent (PES) and sirolimus-eluting stent (SES) expansion based on intravascular ultrasound (IVUS) imaging criteria at conventional delivery pressures. METHODS: Forty-six patients underwent SES implantation and 42 patients underwent PES implantation for de novo native coronary lesions<33 mm in length with reference lumen diameters of 2.5-3.5 mm. Stents were serially expanded with gradual balloon inflations at 14 and 20 atm. IVUS imaging was performed prior to intervention and after each balloon inflation. Stent expansion (minimal stent cross-sectional area/reference lumen cross-sectional area) was measured. Inadequate stent expansion was defined using the MUSIC criteria (all struts apposed, no tissue protrusion, and final lumen cross-sectional area>80% of the reference or >90% if minimal lumen cross-sectional area was <9 mm2). RESULTS: The baseline characteristics of the two groups were similar except for shorter lesion length, larger mean lumen cross-sectional area, larger lumen diameter, and lower plaque burden in the PES group. Stent expansion was inadequate in 80% of patients with SES versus 63% of patients with PES at 14 atm, although this was not statistically significant. After 20 atm, 48% of patients with SES remained underexpanded as compared with 35% of patients with PES. CONCLUSION: Drug-eluting stents showed significant underexpansion by MUSIC criteria at conventionally used inflation pressures. Higher balloon inflations are required especially during deployment of a SES. IVUS guidance is recommended to ensure optimal results and outcomes with both stents.     

Intracoronary Stenting for Restenosis: Long-Term Follow-up: A Single Center Experience

One-hundred thirteen stents (78 Wallstents, 29 Palmaz-Schatz and 6 Wiktor) were implanted in 106 patients aged 63 +/- 5 years to treat a restenosis following previous angioplasty in a native coronary artery (86 cases) and in a venous graft (20 cases). Implantation was technically possible in all cases. The native vessels had a mean reference diameter of 3.3 +/- 0.3 mm and their mean minimal lumen diameter increased from 1.2 +/- 0.3 mm before angioplasty to 2.8 +/- 0.8 after stent implantation. The venous grafts mean reference diameter was 4.4 +/- 0.7 mm and their mean minimal lumen diameter increased from 1.3 +/- 0.4 mm before angioplasty to 4.0 +/- 0.7 mm after implantation. Percentage stenosis in the native arteries and in the venous grafts were respectively 78 +/- 13% and 69 +/- 14% before angioplasty and 24 +/- 8% and 22 +/- 8% after stent implantation. Complications at 6 months, presented as a ranking scale with 100% follow-up rate were, overall, of 20% clinical events (4% deaths, 6% myocardial infractions, 2% coronary artery bypass grafting and 8% re-angioplasty). Angiographic complications were of 8% subacute thrombosis and 19% restenosis and chronic occlusions. Long-term, at 65 +/- 9 months, clinical (86% follow-up) and angiographic (74% follow-up) showed that only a further 9% clinical events and 14% restenosis (12% of them between 6 and 12 months) occurred after 6 months. At an estimated follow-up time of 104 months, 70% patients remain event-free and the survival rate is 95%. In conclusion, stent implantation in the treatment of restenosis following conventional balloon angioplasty is a valid strategy with good long-term results.     

A prospective evaluation of angiography-guided coronary stent implantation with high versus very high balloon inflation pressure

BACKGROUND: High inflation pressure (HP) after coronary stent deployment has become a standard approach because it has been associated with a decreased subacute stent thrombosis (SAT) rate. However, the impact of HP on long-term outcomes is still unclear. We compared the long-term results of a strategy of increasing HP (>/=12 atm) until the achievement of angiographic success (<20% residual stenosis) with a prespecified very high inflation pressure (VHP) strategy of 20 atm without intermediate inflations. METHODS AND RESULTS: We conducted a parallel-group, nonrandomized study to evaluate the short- and long-term results in 136 consecutive eligible patients who underwent successful single Palmaz-Schatz stent implantation in vessels >/=3 mm. Major adverse cardiac events (MACE), that is, death, myocardial infarction, and target lesion revascularization (TLR), were monitored for a minimum of 6 months. No significant differences were observed between the two strategies in terms of final minimal lumen diameter (HP, 3.0 +/- 0.5 vs VHP, 3. 1 +/- 0.5 mm) and acute gain (HP, 2.1 +/- 0.7 vs VHP, 2.2 +/- 0.6). The overall rate of subacute stent thrombosis was 0.7%. During a 405 +/- 148-day follow-up, 21 (28.8%) patients in the VHP group and 6 (9. 5%) in the HP group (P =.005) had MACE, with a TLR rate of 27.4% versus 7.9% (P =.009), respectively. By multivariate analysis, the use of VHP increased the odds of long-term MACE by a factor of 3.48 (P =.009). Among patients undergoing TLR, those treated with VHP had a greater lumen loss (HP, 1.83 +/- 0.57 vs VHP, 2.15 +/- 0.36 mm, P =.02) and a more frequent pattern of diffuse restenosis (71% vs 16%, P =.06). CONCLUSIONS: In our study, the two strategies had similar acute and short-term results, but VHP was associated with a poorer long-term outcome. These data provide a rationale for a less aggressive strategy for stent deployment by optimizing rather than attempting to maximize inflation pressure and stent expansion.     

普通球囊与切割球囊成形术对冠状动脉支架内再狭窄的近远期疗效

目的　对切割球囊成形术 (CBA)与普通球囊成形术 (POBA)支架内再狭窄病变的近远期血管造影结果比较 ,评价 CBA对支架内再狭窄病变的有效性。方法　 37例 ,共 39处病变 ,2 3处进入 CBA组 ,16处进入 POBA组。分别比较术后即刻及远期定量冠状动脉造影最小血管径 (ML D)、狭窄度 (DS)、再狭窄率、即刻管腔获得 (AL G)、即刻血管弹性回缩 (AR)及弹性回缩率 (ARR)。结果　术后即刻 ML D、DS、AL G两组差异无显著性。 CBA组最大扩张压、AR及 ARR均较 POBA组低 (P<0 .0 5或 P<0 .0 0 1)。随访造影结果 ,CBA组 ML D明显大于 POBA组 (P<0 .0 5 ) ;DS及再狭窄率均小于 POBA组 (P<0 .0 1)。结论　 CBA组的低压扩张治疗支架内再狭窄病变是有效的 ,对血管损伤小于 POBA,且获得较 POBA低的再狭窄率 ,值得进一步探讨     

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.     

Incomplete expansion of Palmaz-Schatz stents despite high-pressure implantation technique: impact on target lesion revascularization.

Improved expansion of stents using high-pressure implantation technique with subsequent antiplatelet therapy has improved patient outcome regarding the incidence of subacute stent thrombosis, bleeding complications and restenosis. Whether high-pressure implantation per se guarantees adequate stent expansion remains unclear. The aim of the study was to determine (1) stent expansion after high-pressure implantation technique and (2) whether stent expansion influences rate of target lesion revascularization within 6 months of follow-up. One hundred Palmaz-Schatz stents were implanted in 98 lesions (91 native vessels, 7 graft vessels) of 94 patients using high-pressure implantation technique (balloon pressure 12-20 atm). Stent expansion was investigated using intravascular ultrasound imaging (IVUS). Clinical follow-up of the patients was performed for 6 months. After implantation, stent/mean reference ratio was 0.81 +/- 0.16. Noncompliant balloons used for implantation were chosen by angiographic criteria. Mean balloon/reference ratio was 1.08 +/- 0.22; therefore balloons were not undersized. Additional balloon dilataion using higher pressures and/or larger balloons based on IVUS criteria and subsequent IVUS measurements was performed in 52 patients (55%); in these patients, stent expansion improved from 79 +/- 16 to 91 +/- 15% (mean +/- SD) of average reference areas (p < 0.002). Within the 6 months' clinical follow-up, target lesion revascularization was performed in 19 patients (20%). The only prognostic factors for the development of in-stent restenosis requiring target lesion revascularization were the vessel size (p < 0.05) and the extent of plaque distal to the stents (p < 0.05). Implantation of Palmaz-Schatz stents using high-pressure technique does not guarantee adequate stent expansion. Additional dilatation with higher pressures and/or larger balloons improves stent expansion. The size of the stented vessel and the extent of plaque at the distal stent end (residual outflow stenosis) but not the degree of stent expansion were predictors for target lesion revascularization within 6 months' follow-up.