Quantification of elastic recoil after balloon angioplasty in the iliac arteries

Serration Angioplasty Is Associated With Less Recoil in Infrapopliteal Arteries Compared With Plain Balloon Angioplasty

PURPOSE

Recoil following balloon angioplasty of tibial arteries is a known mechanism of lumen loss and widely considered to be a contributing factor in early failure or later restenosis. The Serranator balloon has been designed to provide a controlled lumen gain while minimizing vessel injury. The objective of this study was to assess the ability to define and measure postangioplasty recoil in infrapopliteal arteries and to compare recoil after serration angioplasty and plain balloon angioplasty (POBA).

METHODS

This multi-center, sequential comparative study included patients with de novo or restenotic lesions of infrapopliteal arteries up to 22 cm in length. Patients were enrolled sequentially and underwent alternating POBA or serration angioplasty with Serranator. The study captured angiographic imaging at pre, immediately post, and 15-minute after angioplasty. Vessel recoil, final diameter stenosis, and dissection were compared using core laboratory analysis.

RESULTS

This study enrolled 36 patients who underwent treatment of 39 infrapopliteal lesions. There was no significant difference between Serranator (n=20) and POBA (n=19) with respect to baseline demographics and lesion characteristics. Arterial recoil (>10%) occurred in 25% of Serranator-treated lesions versus 64% in POBA-treated lesions (p=0.02. Clinically relevant recoil (>30%) was present after serration angioplasty in 10% of patients and after POBA in 53% (p=0.01). There was no significant difference in technical success (100% for both), dissection rate between Serranator (5%) and POBA (5.2%).

CONCLUSIONS

Arterial recoil occurs after infrapopliteal angioplasty. Serration angioplasty produces substantially less arterial recoil compared with POBA. Additional studies are needed to assess whether reduced arterial recoil translates into superior long-term clinical outcomes.

CLINICAL IMPACT

Prior studies have demonstrated over 90% recoil in patients after balloon angioplasty (POBA) of the infrapopliteal vessels, which significantly impacts the durability and impact of endovascular interventions in this clinical space. This study compared recoil after infrapopliteal angioplasty with serration angioplasty and POBA. Serration angioplasty produces substantially less arterial recoil compared with POBA. Additional studies are needed to assess whether reduced arterial recoil translates into superior long-term clinical outcomes.

Endovascular Aneurysm Repair With AFX Stent-Grafts or Tube Grafts for Sacciform Infrarenal Pathologies in a Narrow Aortic Anatomy

PURPOSE

The objective of this study was to compare the outcomes of patients treated with tube grafts and AFX stent-graft in the narrow infrarenal aortic anatomy.

MATERIALS AND METHODS

Patients with penetrating aortic ulcers (PAUs) or sacciform aneurysms of the infrarenal aorta and an aortic bifurcation diameter ≤20 mm who underwent endovascular aneurysm repair (EVAR) with bifurcated AFX or tube stent-grafts (TUBE) between 2012 and 2020 were included. Demographic data and the outcome of the AFX group were compared with the TUBE group. All morphological measurements in the preoperative and postoperative computed tomography scans were performed in the aortic centerline.

RESULTS

Fifty-one patients (female: 12/51; 29%; median age: 72 years [63, 77]) with a median follow-up of 10 (3, 39) months, were included, of whom 35/51 (69%) had PAUs and 11/51 were symptomatic (22%). The aortic bifurcation diameter was 17 mm (15, 18) with severe calcifications in 25/51 (49%). The distal aortic landing zone was longer in the TUBE group (9 mm vs 24 mm; p<0.001). The technical success was 96% with a median aneurysm shrinkage of 8% (3, 13), which was comparable between the groups (p=0.264). Periprocedural mortality, conversion to open surgery, myocardial infarction, and stroke were not observed. Two type Ia endoleaks (EL) and 2 type Ib EL occurred, all in the TUBE group (Type 1 EL; 19 vs 0%; p=0.013). The limb patency in the AFX group was 100%. One patient with a tube graft developed an infrarenal aortic thrombosis 40 months after the intervention. The reintervention rate in the TUBE group was higher (14 vs 0%; p=0.032) and included 3 aortic cuff implantations and 1 covered endovascular aortic reconstruction of aortic bifurcation (CERAB).

CONCLUSION

AFX stent-graft showed a lower rate of type I endoleaks and reinterventions in sacciform infrarenal aortic pathologies during the early and midterm follow-up.

Creating a Natural Vascular Scaffold by Photochemical Treatment of the Extracellular Matrix for Vascular Applications

The development of bioscaffolds for cardiovascular medical applications, such as peripheral artery disease (PAD), remains to be a challenge for tissue engineering. PAD is an increasingly common and serious cardiovascular illness characterized by progressive atherosclerotic stenosis, resulting in decreased blood perfusion to the lower extremities. Percutaneous transluminal angioplasty and stent placement are routinely performed on these patients with suboptimal outcomes. Natural Vascular Scaffolding (NVS) is a novel treatment in the development for PAD, which offers an alternative to stenting by building on the natural structural constituents in the extracellular matrix (ECM) of the blood vessel wall. During NVS treatment, blood vessels are exposed to a photoactivatable small molecule (10-8-10 Dimer) delivered locally to the vessel wall via an angioplasty balloon. When activated with 450 nm wavelength light, this therapy induces the formation of covalent protein–protein crosslinks of the ECM proteins by a photochemical mechanism, creating a natural scaffold. This therapy has the potential to reduce the need for stent placement by maintaining a larger diameter post-angioplasty and minimizing elastic recoil. Experiments were conducted to elucidate the mechanism of action of NVS, including the molecular mechanism of light activation and the impact of NVS on the ECM.

Influence of balloon design, plaque material composition, and balloon sizing on acute post angioplasty outcomes: An implicit finite element analysis

In this work we propose a generic modeling approach for simulating percutaneous transluminal angioplasty (PTA) endovascular treatment, and evaluating the influence of balloon design, plaque composition, and balloon sizing on acute post-procedural outcomes right after PTA, without stent implantation. Clinically-used PTA balloons were classified into two categories according to their compliance characteristics, and were modeled correspondingly. Self-defined elastoplastic constitutive laws were implemented within the plaque and artery models, after calibration based on experimental and clinical data. Finite element method (FEM) implicit solver was used to simulate balloon inflation and deflation. Besides balloon profile at max inflation, results are mainly assessed in terms of the elastic recoil ratio (ERR) and lumen gain ratio (LGR) obtained immediately after PTA. No variations in ERR nor LGR values were detected when the balloon design changed, despite the differences observed in their profile at max inflation. Moreover, LGR and ERR inversely varied with the augmentation of calcification level within the plaque (-11% vs. +4% respectively, from fully lipidic to fully calcified plaque). Furthermore, results showed a direct correlation between balloon sizing and LGR and ERR, with noticeably higher rates of change for LGR (+18% and +2% for LGR and ERR respectively for a calcified plaque and a balloon pressure increasing from 10 to 14 atm). However a larger LGR comes with a higher risk of arterial rupture. This proposed methodology opens the way for evaluation of angioplasty balloon selections towards clinical procedure optimization.

One-year outcomes of drug-coated balloon treatment for long femoropopliteal lesions: a multicentre cohort and real-world study

Background

Drug-coated balloons (DCBs) have shown superiority in the endovascular treatment of short femoropopliteal artery disease. Few studies have focused on outcomes in long lesions. This study aimed to evaluate the safety and effectiveness of Orchid^® DCBs in long lesions over 1 year of follow-up.

Methods

This study is a multicentre cohort and real-world study. The patients had lesions longer than or equal to 150 mm of the femoropopliteal artery and were revascularized with DCBs. The primary endpoints were primary patency, freedom from clinically driven target lesion revascularization (TLR) at 12 months and major adverse events (all-cause death and major target limb amputation). The secondary endpoints were the changes in Rutherford classification and the ankle brachial index (ABI).

Results

One hundred fifteen lesions in 109 patients (mean age 67 ± 11 years, male proportion 71.6%) were included in this study. The mean lesion length was 252.3 ± 55.4 mm, and 78.3% of the lesions were chronic total occlusion (CTO). Primary patency by Kaplan–Meier estimation was 98.1% at 6 months and 82.1% at 12 months. The rate of freedom from TLR by Kaplan–Meier estimation was 88.4% through 12 months. There were no procedure- or device-related deaths through 12 months. The rate of all-cause death was 2.8%. Cox regression analysis suggested that renal failure and critical limb ischaemia (CLI) were statistically significant predictors of the primary patency endpoint.

Conclusion

In our real-world study, DCBs were safe and effective when used in long femoropopliteal lesions, and the primary patency rate at 12 months by Kaplan–Meier estimation was 82.1%.

The influence of angioplasty balloon sizing on acute post-procedural outcomes: a Finite Element Analysis

Atherosclerosis is one of the most common vascular pathologies in the world. Among the most commonly performed endovascular treatments, percutaneous transluminal angioplasty (PTA) has been showing significantly positive clinical outcomes. Due to the complex geometries, material properties and interactions that characterize PTA procedures, finite element analyses of acute angioplasty balloon deployment are limited. In this work, finite element method (FEM) was used to simulate the inflation and deflation of a semi-compliant balloon within the 3D model of a stenosed artery with two different plaque types (lipid and calcified). Self-defined constitutive models for the balloon and the plaque were developed based on experimental and literature data respectively. Balloon deployment was simulated at three different inflation pressures (10, 12 and 14 atm) within the two plaque types. Balloon sizing influence on the arterial elastic recoil obtained immediately after PTA was then investigated. The simulated results show that calcified plaques may lead to higher elastic recoil ratios compared to lipid stenosis, when the same balloon inflation pressures are applied. Also, elastic recoil increases for higher balloon inflation pressure independent of the plaque type. These findings open the way for a data-driven assessment of angioplasty balloon sizing selection and clinical procedures optimization.Clinical Relevance- The FE model developed in this work aims at providing quantitative evaluation of recoil after balloon angioplasty. It may be useful for both manufacturers and clinicians to improve efficiency of angioplasty balloon device design and sizing selection with respect to plaque geometry and constitution, consequently enhancing clinical outcomes.

Drug-eluting balloons with provisional bail-out or adjunctive stenting in de novo coronary artery lesions-a systematic review and meta-analysis

Background

Efficacy of drug-eluting balloons (DEB) for treatment of de novo coronary lesions remains controversial. The present systematic review and meta-analysis of randomised controlled trials assessed DEB with bare-metal stents (BMS) and also DEB with provisional bail-out stents ('DEB-only' strategy), to other conventional options: plain-old balloon angioplasty (POBA), BMS and drug-eluting stents (DES).

Methods

A systematic literature search from January 2000 until May 2017 was conducted. Primary outcome measure, late lumen loss (LLL); and secondary outcomes; binary restenosis, major adverse cardiac events (MACE), target lesion revascularization (TLR), myocardial infarction (MI), cardiovascular death and stent thrombosis were analysed.

Results

Seventeen RCTs were included with 2,616 patients. Several comparative groups showed significant differences. DEB with BMS were inferior to DES for LLL [mean difference (MD) =0.12 mm; 95% confidence interval (CI), 0.03 to 0.22; P=0.01]; and binary restenosis [risk ratio (RR) =1.89; (CI, 1.13 to 3.18); P=0.02]. DEB with BMS was superior to BMS for LLL [MD =-0.27 mm; (-0.45 to -0.10); P=0.002]; and MACE [RR =0.64; (0.46 to 0.90); P=0.010]. Finally, DEB alone was superior to POBA for LLL [MD =-0.39 mm; (-0.67 to -0.11); P=0.006] and binary restenosis [RR =0.20; (0.05 to 0.85); P=0.03] in bifurcation lesions.

Conclusions

The results of this meta-analysis showed that whilst DEB with BMS is superior to BMS alone, the combination is inferior to DES for treatment of de novo coronary lesions. Thus, DEB + BMS should not be applied in de novo lesions unless in patients who have absolute contraindications to DES. DEB alone, however, should be considered for relative contraindications to DES such as small vessel disease and bifurcation lesions.

Recombinant Human Elastase Alters the Compliance of Atherosclerotic Tibial Arteries After Ex Vivo Angioplasty

Supplemental Digital Content is Available in the Text.

Purpose:

This study was designed to determine whether vonapanitase (formerly PRT-201), a recombinant human elastase, treatment can fragment the protein elastin in elastic fibers and cause dilation of atherosclerotic human peripheral arteries subjected to ex vivo balloon angioplasty.

Materials and Methods:

Seven patients undergoing lower limb amputation for peripheral artery disease or who died and donated their bodies to science donated 11 tibial arteries (5 anterior, 6 posterior) for this study. All arteries were atherosclerotic by visual inspection. The arteries underwent ex vivo balloon angioplasty and thereafter were cut into rings and studied on wire myographs where the rings were stretched and tension was recorded. After treatment with vonapanitase 2 mg/mL or vehicle control, myography was repeated and the rings were then subject to elastin content measurement using a desmosine radioimmunoassay and elastic fiber visualization by histology. The wire myography data were used to derive compliance, stress-strain, and incremental elastic modulus curves.

Results:

Vonapanitase treatment reduced elastin (desmosine) content by 60% and decreased elastic fiber histologic staining. Vonapanitase-treated rings experienced less tension at any level of stretch and as a result had shifts in the compliance and stress-strain curves relative to vehicle-treated rings. Vonapanitase treatment did not alter the incremental elastic modulus curve.

Conclusions:

Vonapanitase treatment of atherosclerotic human peripheral arteries after ex vivo balloon angioplasty fragmented elastin in elastic fibers, decreased tension in the rings at any level of stretch, and altered the compliance and stress-strain curves in a manner predicting arterial dilation in vivo. Based on this result, local treatment of balloon angioplasty sites may increase blood vessel diameter and thereby improve the success of balloon angioplasty in peripheral artery disease.

Cryoplasty for the Treatment of Femoropopliteal Arterial Disease: Extended Follow-up Results

Purpose:

To report the findings from a multicenter study of patients treated with cryoplasty who were then followed for an average of >2 years post-treatment.

Methods:

Extended clinical follow-up was obtained for 70 patients (45 men; mean age 70.5±8.8 years) who originally received cryoplasty therapy to treat symptoms of intermittent claudication as part of a multicenter investigational device exemption (IDE) study. For all subjects, cryoplasty was used to treat stenoses or occlusions ≤10 cm in the femoropopliteal arteries. The original IDE study protocol enrolled 102 patients with a primary endpoint of target lesion patency at 9 months post-treatment. This collection of additional longer term follow-up data was initiated 2.5 years after the onset of study enrollment.

Results:

Extended clinical follow-up ranged from 11 to 41 months (mean 31). The clinical patency rate (freedom from target lesion revascularization) calculated by the Kaplan-Meier method was 83.2% after the original follow-up period of 300 days. After >3 years (1253 days), the clinical patency rate was well maintained at 75.0%.

Conclusions:

Long-term data indicate that cryoplasty is a durable therapy, with relatively low long-term restenosis rates compared to other endovascular treatment approaches.

Paclitaxel Drug-eluting Balloons to Recurrent In-stent Stenoses in Autogenous Dialysis Fistulas: A Retrospective Study

Purpose

To assess the effect of the Medtronic paclitaxel drug-eluting balloon (DEB) on re-intervention to in-stent stenoses in autogenous dialysis arteriovenous fistulas (AVFs).

Background

AVF is the optimum haemodialysis access. The commonest problem is stenosis, preventing maturation, causing inadequate dialysis or precipitating occlusion. Conventional angioplasty has a high recurrence rate. Successful drug elution in the coronary circulation led us to use DEBs in recurrent AVF stenoses since 2010.

Methods

This is a retrospective study, based on prospective audit data, using DEBs on recurrent in-stent stenotic lesions in the AVF circuit of our haemodialysis population. To analyse the effect of DEBs on re-intervention, we created two Kaplan–Meier curves. The first curve compares the last “disease-free-interval” pre-DEB intervention to the first “disease-free interval” post-DEB, giving us “re-intervention-free percentage at 12 months” pre- and post-DEB. The second curve takes into account the multiple pre- and post-DEB interventions to the index lesion, and uses a marginal proportional hazards model to estimate the hazard ratio for “DEBpresent vs. DEBabsent”.

Results

From 1 September 2010 to 1 December 2013, we treated 625 AVF stenoses with endovascular techniques. In 86 of these stenoses, DEBs were used. Of the 86 DEB interventions, 37 were included for this study, 49 were excluded. In the study group, there was a significant difference in “re-intervention-free percentage at 12 months” before and after DEB: 19% vs. 69%. The hazard ratio for “DEBpresent” vs. “DEBabsent” was 0.23 (95% CI 0.14 to 0.36, p<0.001).

Conclusions

This retrospective study suggests that DEBs significantly reduce re-intervention on recurrent in-stent AVF stenoses.

Preclinical Models of Restenosis and Their Application in the Evaluation of Drug-Eluting Stent Systems

Coronary arterial disease (CAD) is the leading cause of death in the United States, the European Union, and Canada. Percutaneous coronary intervention (PCI) has revolutionized the treatment of CAD, and it is the advent of drug-eluting stent (DES) systems that has effectively allayed much of the challenge of restenosis that has plagued the success of PCI through its 30-year history. However, DES systems have not been a panacea: There yet remain the challenges associated with interventions involving bare metallic stents as well as newly arisen concerns related to the application of DES systems. To effectively address these novel and ongoing issues, animal models are relied on both to project the safety and efficacy of endovascular devices and to provide insight into the pathophysiology underlying the vascular response to injury and mechanisms of restenosis. In this review, preclinical models of restenosis are presented, and their application and limitation in the evaluation of device-based interventional technologies for the treatment of CAD are discussed.

Embolic Protection and Platelet Inhibition During Renal Artery Stenting

Background— Preservation of renal function is an important objective of renal artery stent procedures. Although atheroembolization can cause renal dysfunction during renal stent procedures, whether adjunctive use of embolic protection devices or glycoprotein IIb/IIIa inhibitors improves renal function is unknown.

Methods and Results— One hundred patients undergoing renal artery stenting at 7 centers were randomly assigned to an open-label embolic protection device, Angioguard, or double-blind use of a platelet glycoprotein IIb/IIIa inhibitor, abciximab, in a 2×2 factorial design. The main effects of treatments and their interaction were assessed on percentage change in Modification in Diet in Renal Disease–derived glomerular filtration rate from baseline to 1 month using centrally analyzed creatinine. Filter devices were analyzed for the presence of platelet-rich thrombus. With stenting alone, stenting and embolic protection, and stenting with abciximab alone, glomerular filtration rate declined ( P <0.05), but with combination therapy, it did not decline and was superior to the other allocations in the 2×2 design ( P <0.01). The main effects of treatment demonstrated no overall improvement in glomerular filtration rate; although abciximab was superior to placebo (0±27% versus −10±20%; P <0.05), embolic protection was not (−1±28% versus −10±20%; P =0.08). An interaction was observed between abciximab and embolic protection ( P <0.05), favoring combination treatment. Abciximab reduced the occurrence of platelet-rich emboli in the filters from 42% to 7% ( P <0.01).

Conclusions— Renal artery stenting alone, stenting with embolic protection, and stenting with abciximab were associated with a decline in glomerular filtration rate. An unanticipated interaction between Angioguard and abciximab was seen, with combination therapy better than no treatment or either treatment alone.

Median arcuate ligament syndrome: open celiac artery reconstruction and ligament division after endovascular failure

Median arcuate ligament syndrome (MALS) is a rare disorder resulting from extrinsic compression and narrowing of the celiac artery, and--less often--the superior mesenteric artery, by the relatively low insertion of the ligament and/or prominent fibrous bands or ganglionic periaortic tissue of the celiac nervous plexus. We report on a young woman who after three consecutive attempts of endovascular therapy with balloon angioplasty and stenting for MALS, each followed by gross symptom recurrence and a cumulative weight loss of 10 kg, underwent open surgical division of the ligament and reconstruction of the celiac artery. Despite the initial response of MALS to endovascular therapy, the extrinsic pressure exerted on the celiac artery by the surrounding dense fibrous/ganglionic tissue resulted in slippage of the stents and/or failure of their material. These findings militate against the use of balloon angioplasty and stenting primarily in patients with MALS without prior release of the extrinsic compression on the celiac (and/or superior mesenteric) artery by dividing the surrounding median arcuate ligament and/or ganglionic tissue with open or laparoscopic surgery.

Immediate structural changes of porcine renal arteries after angioplasty: a histological and morphometric study

The aim of this research was to characterize the immediate alterations induced by angioplasty and to compare the results of the application of two types of balloons. Ten porcine renal arteries were dilated with a compliant balloon, and ten with a non-compliant balloon. After angioplastic treatment arterial specimens were wax embedded for light microscopy. Sections were stained with the orcein-Van Gieson method, orcein, haematoxylin-eosin, and PAS. Image analysis was performed taking into consideration the following parameters: thickness of the entire wall, of the tunica media and of the inner elastic lamina. The major axes of the smooth muscle cells nuclei were also measured. The effects of the two types of balloon resulted in changes consisting in thinning of the entire arterial wall, reduction of the tunica media, distension of reticular fibers, presence of wide spaces between smooth muscle cells, stretching of smooth muscle cells, inner elastic lamina thickening. Both angioplasty devices used can modify the vascular wall. The identification of the tunica media structural damages might be useful in order to estimate the behavior of the vascular wall in the follow-up after angioplasty, because the entity of modifications could be predictive of restenosis that often takes place weeks or months after angioplasty.

Cryoplasty for the Treatment of Femoropopliteal Arterial Disease: Results of a Prospective, Multicenter Registry

PURPOSE

Despite suboptimal results, angioplasty of femoropopliteal arterial lesions has been a mainstay of endovascular therapy for many years. The recent introduction of cryoplasty marks a potential advance in the ability to effectively treat peripheral arterial atherosclerotic stenoses. This article presents the results of a prospective, multicenter trial that evaluated the efficacy of cryoplasty for femoropopliteal disease.

MATERIALS AND METHODS

One hundred two patients with claudication and lesions of the superficial femoral and popliteal arteries of no greater than 10 cm were studied. All patients were treated with a primary strategy of stand-alone cryoplasty with use of the PolarCath cryoplasty system. The primary endpoints of the study were acute technical success and clinical patency at 9 months. Technical success was defined as the ability to achieve residual angiographic stenosis no greater than 30% and residual stenosis less than 50% by duplex ultrasound (US) imaging. Clinical patency was defined as freedom from target lesion revascularization within 9 months. Primary patency was defined by a duplex US systolic velocity ratio no greater than 2.0.

RESULTS

A total of 102 patients were enrolled at 16 centers. Of those treated, 31% had diabetes and 31% were active cigarette smokers. The majority of the lesions were confined to the superficial femoral artery (84.3%) and 14.7% presented with total occlusions. The mean vessel diameter treated was 5.5 mm +/- 0.5, the mean stenosis diameter was 87% +/- 10%, and the mean lesion length was 4.7 cm +/- 2.6. The technical success rate was 85.3% with a mean residual stenosis after cryoplasty of 11.2% +/- 11.2% (P < .05 vs baseline). Clinical patency in this group was 82.2%, as only 16 patients required target lesion revascularization during the 9-month surveillance period. Primary patency determined by duplex US was 70.1%.

CONCLUSIONS

Cryoplasty demonstrated a high degree of acute angiographic success and a low frequency of target lesion revascularization. The patency rate observed compares favorably to that previously documented with conventional angioplasty.

Angiographic Assessment of Initial Balloon Angioplasty Results

PURPOSE

To determine the influence of three factors involved in the angiographic assessment of balloon angioplasty-interobserver variability, operator bias, and the definition used to determine success-on the primary (technical) results of angioplasty in the peripheral arteries.

MATERIALS AND METHODS

Percent stenosis in 107 lesions in lower-extremity arteries was graded by three independent, experienced vascular radiologists ("observers") before and after balloon angioplasty and their estimates were compared with the initial interpretations reported by the physician performing the procedure ("operator") and an automated quantitative computer analysis. Observer variability was measured with use of intraclass correlation coefficients and SD. Differences among the operator, observers, and the computer were analyzed with use of the Wilcoxon signed-rank test and analysis of variance. For each evaluator, the results in this series of lesions were interpreted with three different definitions of success.

RESULTS

Estimation of residual stenosis varied by an average range of 22.76% with an average SD of 8.99. The intraclass correlation coefficients averaged 0.59 for residual stenosis after angioplasty for the three observers but decreased to 0.36 when the operator was included as the fourth evaluator. There was good to very good agreement among the three independent observers and the computer, but poor correlation with the operator (P </= .001). The primary success rates for this series of lesions varied from a low of 47% to high of 99%, depending solely on which definition of success was used. Significant differences among the operator, the three observers, and the computer were not present when the definition of success was based on less than 50% residual stenosis.

CONCLUSIONS

Observer variability and bias in the subjective evaluation of peripheral angioplasty can have a significant influence on the reported initial success rates. This effect can be largely eliminated with the use of residual stenosis of less than 50% to define success. Otherwise, meaningful evaluation of angioplasty results will require independent panels of evaluators or computerized measurements.