Plaque morphology and pathologic changes in arteries from patients dying after coronary balloon angioplasty

A unique mechanism of restenosis after drug-coated balloon in peripheral artery: Insight from optical frequency domain imaging

Drug-coated balloons (DCBs) have been widely used in endovascular therapy for femoropopliteal arteries with atherosclerotic lesions. Vascular response after DCBs remains unclear. This mini-review proposes a possible mechanism of restenosis after the DCB strategy. Balloon dilatation including DCBs expands the vascular lumen by producing dissections, which is composed of the original vascular lumen and the cavity surrounded by dissected flaps. The cavity surrounded by dissected flaps is eventually replaced with the thrombus in the healing process after balloon dilatation. However, the thrombus may propagate to the expanded vascular lumen through the entry point of the dissection. Subsequently, the thrombus both in the cavity and the expanded lumen would be organized over time. The vascular lumen in the chronic-phase after DCBs may be influenced by the propagated thrombus from the cavity surrounded by dissected flaps.

The Mechanism of Balloon Impact in Percutaneous Transluminal Coronary Angioplasty in Eccentric Coronary Artery Narrowings

In the early days of percutaneous transluminal coronary angioplasty (PTCA) and in particular before the stent era, the selection of the appropriate balloon diameter was crucial for risk and success of the intervention. With larger balloon diameters the risk of vessel wall dissection was increased but the rate of restenosis was much higher when smaller balloons were used. In retrospect, it is surprising how few histopathological studies have been performed during this time period to study the mechanism of PTCA. A main reason for this may have been that PTCA has been working well in most cases and was very effective for the relief of angina symptoms. This lack of basic research led even to the erroneous assumption by the PTCA pioneer Andreas Gruentzig, that the angioplasty procedure be characterized "by a concentric expansion of the vessel over a suitable portion of its length." This view has been challenged by Professor Jesse E. Edwards, a distinguished cardiovascular pathologist from Minneapolis, MN/USA, with a world-wide reputation. The disagreement was based on the finding that 70% of coronary stenoses have been found to be eccentric and only 30% to be concentric narrowings. Jesse E. Edwards therefore initiated a histopathological study about the mechanism of balloon angioplasty in coronary arteries of freshly autopsied hearts. The study was performed in 1982 by one of the authors (HS), then a young cardiology fellow in the laboratories of Professor Kurt A. Amplatz. Kurt A. Amplatz was in an early stage of his career to later become a world famous pioneer for the development of a variety of catheters, wires, instruments, and devices for the closure of the patent foramen ovale, atrial and ventricular septal defects, and the left atrial appendage. The study documents were unavailable for almost 40 years but have recently been made accessible again. Conclusion: This manuscript discusses the main findings of the histopathological study on the mechanism of coronary balloon dilatation and is dedicated to 2 giants of cardiovascular research, Jesse E. Edwards and Kurt A. Amplatz.

Perfusion Balloon for the Treatment of Very Late Stent Thrombosis

A method to manage ST-segment elevated myocardial infarction (STEMI) caused by very late stent thrombosis (VLST) has yet to be established. In this case series, we present several cases of STEMI caused by VLST, which were successfully revascularized using a perfusion balloon. Since the perfusion balloon (Ryusei: Kaneka Medix Corporation, Osaka, Japan) has the unique advantage of maintaining blood flow during balloon inflation, we can keep dilating the target lesion for more than several minutes. Extended inflation might work to prevent acute recoil, and to achieve optimal expansion without an additional stent. Our case series may provide a reasonable option for the treatment of VLST.

Mechanism of Drug-Eluting Absorbable Metal Scaffold Restenosis

Background:

The pathomechanisms underlying restenosis of the bioabsorbable sirolimus-eluting metallic scaffold (Magmaris) remain unknown. Using serial optical coherence tomography, we investigated causes of restenosis, including the contribution of late scaffold recoil versus neointimal hyperplasia.

Methods:

Patients enrolled in BIOSOLVE-II undergoing serial angiography and optical coherence tomography (post-intervention and follow-up: 6 months and/or 1 year) were analyzed. Patients were divided into 2 groups according to angiographic in-scaffold late lumen loss (LLL) <0.5 or ≥0.5 mm. End points were late absolute scaffold recoil and neointimal hyperplasia area as assessed by optical coherence tomography.

Results:

Serial data were available for analysis from 70 patients (LLL <0.5 mm: n=41; LLL ≥0.5 mm: n=29). Patient and lesion characteristics were comparable, and there was no significant difference in mean and minimal scaffold area between groups at post-intervention. Late absolute scaffold recoil was less among patients with LLL <0.5 mm (0.53±0.68 mm 2 ) compared with those with LLL ≥0.5 mm (1.48±1.20 mm 2 ; P <0.001). Neointimal hyperplasia area was smaller among patients with LLL <0.5 mm at follow-up (1.47±0.33 mm 2 ) compared with patients with LLL ≥0.5 mm (1.68±0.34 mm 2 ; P =0.013). In a matched-frame analysis (post-intervention and follow-up), late absolute scaffold recoil varied according to the underlying plaque type (lipid: 0.63±1.23 mm 2 ; calcified: 0.81±1.44 mm 2 ; and fibrous: 1.20±1.52 mm 2 ; P <0.001), while there was no difference with regards to neointimal hyperplasia area ( P =0.132).

Conclusions:

In addition to neointimal hyperplasia, late scaffold recoil contributed significantly to LLL of sirolimus-eluting absorbable metal scaffolds. The extent of late scaffold recoil was dependent on the underlying plaque morphology and was the highest among fibrotic lesions.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01960504.

A Case of an Obstructive Intramural Haematoma during Percutaneous Coronary Intervention Successfully Treated with Intima Microfenestrations Utilising a Cutting Balloon Inflation Technique

During percutaneous coronary interventions (PCI), good lesion preparation with adequate balloon predilatation is a fundamental step before stent deployment in order to achieve optimal stent expansion and favourable long-term outcomes post PCI. During PCI, inadvertent vessel tearing can occur, resulting in coronary dissections and formation of intramural haematomas. The latter might be associated with compression of the vessel lumen and significant compromise of the coronary blood flow leading to myocardial ischaemia and infarction. Herein, we present a case of intramural haematoma that occurred after PCI of the left anterior descending artery resulting in occlusion of the vessel and the subsequent use of a cutting balloon inflation technique to resolve the haematoma and restore the normal coronary blood flow.

The effect of statin treatment on the prevention of stent mediated flow limited edge dissections during PCI in patients with stable angina

OBJECTIVES

The effect of statin therapy before PCI with direct stenting may reduce the development of flow limited edge dissections (ED) in patients with stable angina.

BACKGROUND

Flow limited ED after PCI is associated with an increased risk of major adverse cardiovascular events. Statin therapy induces important changes in the plaque composition which have been previously identified as strong predictors of ED.

MATERIAL AND METHODS

100 patients complicated with flow limited ED and 100 control patients with successful procedure were enrolled into the study. EDs were described as the 5-mm regions that were immediately adjacent to the stent borders, both distally and proximally on the coronary angiography.

RESULTS

Rate of statin use and duration of statin use were significantly higher in patients with non-ED group (63%) versus ED group (25%) (p<0.001). In addition, patients in ED group had significantly higher levels of C-reactive protein (CRP) at admission (9.9mg/dL (5.89-16.45) vs. 4.40mg/dL (3.5-7.09), respectively, p=0.014).

CONCLUSIONS

Our findings suggested that maintenance statin treatment before PCI with direct stenting may reduce the development of flow limited ED in patients with stable angina.

Intravascular Ultrasound Guidance for Peripheral Vascular Interventions

Intravascular ultrasound (IVUS) imaging during peripheral endovascular interventions adds important information regarding the distribution of disease by providing controlled measurements of the cross-sectional area of the vessel lumen and wall prior to and following procedures. IVUS is useful in determining the mechanism and efficacy of balloon angioplasty, in guiding atherectomy devices, and in assuring appropriate placement of intravascular stents. The incorporation of an IVUS element into catheter-based interventional devices may improve the immediate and long-term results of endovascular interventions by decreasing complications from dissection and perforation of the arterial wall. Combined IVUS-stent prototype catheters are being developed to enable imaging and deployment simultaneously. Similar devices are being explored to enhance expedient, precise delivery of endoluminal grafts. Future studies of endovascular techniques should include IVUS, when possible, to accurately quantitate the initial efficacy of devices and to determine the nature and distribution of recurrent lesions.

Multi-modality imaging for stent edge assessment

Optical coherence tomography (OCT) has a sufficiently high resolution to allow assessment of stent edge dissection (ED). The aims of the present study were as follows: (1) evaluation of the frequency of stent ED using OCT; (2) comparison of stent ED detection rates obtained using angiography, intravascular ultrasound (IVUS), and OCT; and (3) IVUS-Virtual Histology (IVUS-VH) evaluation of plaque composition at the site of stent EDs detected by OCT after percutaneous coronary intervention (PCI). Fifty-eight consecutive patients (59 lesions, 100 stent edges) who underwent balloon-expandable stent implantation and post-stent assessment with OCT and IVUS-VH were included. OCT revealed stent ED in 24.0 % (24 of 100) of stent edges after PCI with a balloon-expandable stent. In contrast, ED was detected in only 3.0 % (3 of 100) of stent edges using angiography and 4.0 % (4 of 100) of stent edges using IVUS. Plaque evaluation using IVUS-VH showed that the percent necrotic core (21.2 ± 8.3 vs. 13.4 ± 10.7 %, p = 0.001) and absolute dense calcium (2.9 ± 2.4 vs. 1.3 ± 2.2 mm(3), p = 0.0104) and dense calcium (13.8 ± 9.3 vs. 5.4 ± 5.8 %, p < 0.001) volumes were greater in the ED group than in the non-ED group. Thus, OCT is superior to conventional coronary angiography and IVUS in the identification of stent ED. In addition, the plaque composition at the ED site is characterized by a necrotic core and greater dense calcium levels than those observed at the non-ED site.

Molecular atherectomy for restenosis

Receptors for basic (b) and acidic (a) fibroblast growth factor (FGF) are upregulated in activated smooth muscle cells. These cells, which proliferate in response to bFGF, can thus be killed by a conjugate of bFGF and the ribosome-inactivating enzyme, saporin (which, by itself, does not enter the cells). Quiescent smooth muscle cells and other cells that have few FGF receptors are not killed. In vivo, bFGF-saporin transiently inhibits smooth muscle cell proliferation and neointimal accumulation after balloon injury to the rat carotid artery. Delivery of saporin, diagnostic imaging agents, or antisense oligodeoxynucleotides might be made even more selective by linking these substances to antibodies against the extracellular domains of the putative FGF receptor isoform specific for activated smooth muscle cells.

Late loss in a disappearing frame of reference: is it still applicable to fully absorbable scaffolds?

Bioabsorbable stents are an important advancement in stent technology providing a temporary scaffold and may be augmented with drugs to suppress neointimal hyperplasia.Though changes are being made to the design of the stents, to ensure similar rates of acute recoil, residual stenosis postintervention remains higher when compared to contemporary durable stents. In order to achieve similar clinical restenosis outcomes, bioabsorbable stents must first show similar MLD or percent diameter stenosis at follow-up to drug-eluting stents.While variable different acute gain and post-procedure MLD for bioabsorbable stents make late lumen loss a poor marker for restenosis probability by itself, late loss can be an informative metric for neointimal hyperplasia over time in these stents.Metrics which are independent of acute gain such as minimal luminal diameter and percentage diameter stenosis may make better surrogates for restenosis (Table 1). Moreover, remodelling over time requires measurement of the vessel and lumen diameters in later follow-up. Since the natural history of the vascular response to bioabsorbable stents is in its infancy of investigation, follow-up of these stents at least beyond the duration of polymer is prudent. Finally, given a disappearing frame of reference, both careful angiographic and intravascular ultrasound assessments are helpful to delineate the varying contributions of recoil, remodelling, and neointima formation.

Intravascular ultrasound-guided troubleshooting in a large hematoma treated with fenestration using a cutting balloon

Intramural hematoma formation is not a well-studied complication of percutaneous coronary intervention. We describe a patient with stable angina who developed an intramural hematoma during elective percutaneous coronary intervention (PCI) in the right coronary artery (RCA). Total occlusion with dense dye staining developed a long way from the distal RCA, near the posterior descending artery bifurcation site. The true lumen was compressed by the enlarged, tense, false lumen. The patient was successfully treating with intravascular ultrasound-guided fenestration using a cutting balloon, and a stent was implanted in the distal RCA.

Sequential patterns of chemokine- and chemokine receptor-synthesis following vessel wall injury in porcine coronary arteries

Inflammation plays a central role in vascular repair, and spreads into perivascular tissue (PVT) following angioplasty. Chemokines (CK) and chemokine receptors (CKR) are key determinants of inflammatory chemotaxis. We sought to assess the arterial and perivascular expression of the CK CCL2 and CXCL2, and the CKR CCR2, CCR5, and CXCR4 in balloon-injured porcine coronary arteries. Vascular cells that express specific CK and CKR mRNA during post-angioplasty time course were detected by in situ hybridization (ISH), and expression was quantified by real time RT-PCR in PVT. CCL2 was maximal in PVT from 2 to 24h post injury, coincident with local macrophage-activation. Expression was upregulated in media and adventitia from 24h to 3 days, and in neointima at 7 days. CXCL2 was detected in media at 2 and 4h, and also in some neointimal cells. CCR2 and CCR5 were maximal in PVT at 24h and 3 days, respectively. Expression shifted to media and adventitia at 2 and 3 days, and to neointima and adventitia at 7 days, and was low at 14 days. CXCR4 was low in PVT, but was upregulated in media and adventitia at 2 and 3 days, as well as in neointima and adventitia at 7 days. In conclusion, PVT is the primary source of inflammatory CK and CKR early post-angioplasty. Specific sequential patterns of CK- and CKR-synthesis are identified that may regulate phase-specific chemotaxis by spatio-temporally differential expression during coronary response to injury.

In stent restenosis: bane of the stent era

The long term outcome of stent implantation is affected by a process called in stent restenosis (ISR). Multiple contributory factors have been identified, but clear understanding of the overall underlying mechanism remains an enigma. ISR progresses through several different phases and involves numerous cellular and molecular constituents. Platelets and macrophages play a central role via vascular smooth muscle cell migration and proliferation in the intima to produce neointimal hyperplasia, which is pathognomic of ISR. Increased extracellular matrix formation appears to form the bulk of the neointimal hyperplasia tissue. Emerging evidence of the role of inflammatory cytokines and suppressors of cytokine signalling make this an exciting and novel field of antirestenosis research. Activation of Akt pathway triggered by mechanical stretch may also be a contributory factor to ISR formation. Prevention of ISR appears to be a multipronged attack as no therapeutic "magic bullet" exists to block all the processes in one go.

Intravascular ultrasound: defining plaque regression

Intravascular ultrasound allows accurate assessment of the arterial vessel, including vessel luminal diameter and assessment of vessel disease in terms of plaque morphology, plaque volume and extent of calcification. Recently published trials highlight the role of intravascular ultrasound in monitoring disease progression in a clinical setting.

Extracellular Matrix Changes in Stented Human Coronary Arteries

Background— Restenosis after stenting occurs secondary to the accumulation of smooth muscle cells (SMCs) and extracellular matrix (ECM), with the ECM accounting for >50% of the neointimal volume. The composition of the in-stent ECM has not been well characterized in humans.

Methods and Results— Postmortem human coronary arteries (n=45) containing stents underwent histological assessment of neointimal proteoglycans, hyaluronan, collagen (types I and III), SMCs, and CD44 (a cell surface receptor for hyaluronan). The mean duration of stent implantation was 18.7 months; stents in place ≥3 to <9 months (n=17) were assigned to group 1, stents ≥9 to <18 months old (n=19) to group 2, and stents ≥18 months old (n=9) to group 3. In groups 1 and 2, neointimal versican and hyaluronan staining was strongly positive, colocalized with α-actin-positive SMCs, and was greater in intensity compared with group 3. Conversely, decorin staining was greatest in group 3. The neointima of both group 1 and 2 stents was rich in type III collagen, with reduced staining in group 3. Type I collagen staining was weakest in group 1 stents, with progressively stronger staining in groups 2 and 3. SMC density and stent stenosis were significantly reduced in group 3 stents compared with groups 1 and 2. CD44 staining colocalized with macrophages and was associated with increased neointimal thickness.

Conclusions— The ECM within human coronary stents resembles a wound that is not fully healed until 18 months after deployment, followed by neointimal retraction. ECM contraction may be a target for therapies aimed at stent restenosis prevention.

Histopathological evaluation of middle cerebral artery after percutaneous intracranial transluminal angioplasty

BACKGROUND

Intracranial atherosclerosis accounts for 8% to 10% of all ischemic strokes, and intracranial angioplasty is increasingly performed to treat stenotic lesions. We report an autopsy case and discuss the effects of intracranial angioplasty for atherosclerotic arteries.

CASE DESCRIPTION

A 77-year-old patient died 9 days after angioplasty of the left middle cerebral artery as a result of cardiorespiratory failure. The patient was anticoagulated before, during, and after the procedure with heparin, aspirin, and clopidogrel. At the site of angioplasty, the densely fibrotic eccentric plaque was displaced from the adjacent media into the lumen, distorting it and forming elongated projections. No local thrombosis, plaque compression, or inflammation was observed. Additionally, an intramural hemorrhage extended from the site of angioplasty into the stenotic proximal inferior division of the left middle cerebral artery.

CONCLUSIONS

Histopathological findings after intracranial angioplasty parallel those in other arterial territories. The implications of these pathological findings on the medical and endovascular treatment of intracranial atherosclerosis are discussed.

Intravascular brachytherapy: a review of the current vascular biology

Restenosis is a major limitation of coronary angioplasty, requiring further intervention in the majority of cases. Intracoronary radiation has been employed in recent years to prevent restenosis lesions with effective results, principally in in-stent restenosis. Restenosis is generally considered as an excessive form of normal wound healing divided up in processes: elastic recoil, neointimal hyperplasia, and negative vascular remodeling. Restenosis has previously been regarded as a proliferative process in which neointimal thickening, mediated by a cascade of inflammatory mediators and other factors, is the key factor. Data from recent studies have pointed to negative vascular remodeling as a major contributing factor. Recent studies have also identified particular cell lines that might be critical regulators of restenosis, particularly monocyte-derived macrophages and myofibroblasts. This review summarizes the current theories of vascular biology pertaining to restenosis in coronary arteries and the potential mechanisms of why radiation may effectively inhibit restenosis.

Evaluation of vascular injury following percutaneous transluminal coronary angioplasty: a comparison of the accuracy of two- and three-dimensional intracoronary ultrasound imaging

BACKGROUND

Following percutaneous transluminal coronary angioplasty (PTCA), the extent of vascular injury is underestimated by angiographic assessment. Conventional intracoronary ultrasound (ICUS) imaging provides additional information with regard to the extent of dissections but requires mental reconstruction of consecutive images. Three-dimensional ICUS reconstruction overcomes this limitation and may provide more accurate assessment of the extent of vascular injury. This study compares conventional two-dimensional ICUS imaging to combined two- and three-dimensional ICUS information in the assessment of vascular injury following PTCA.

METHODS

Atherosclerotic, human coronary arteries (n=24) were studied in a specially constructed flow system. Balloon dilatation of significant stenoses was performed followed by assessment using two- and three-dimensional ICUS imaging methods. Treated arteries were submitted for histological assessment after pressure fixation. Dissection depth and length measurements were made from obtained images and compared to histomorphometric assessments.

RESULTS

Of the 20 arterial segments confirmed histologically to contain dissection, 11 (55%) and 18 (90%) were identified by two-dimensional ICUS and combined two- and three-dimensional ICUS respectively. The kappa values for correlation of dissection type were 0.29 (0.23-0.35) and 0.64 (0.57-0.71) respectively indicating better agreement using combined two- and three-dimensional ICUS. Two-dimensional ICUS consistently underestimated dissection length (3.52+/-1.75 mm compared with 6.54+/-2.42 mm, P<0.001) and depth (0.61+/-0.24 mm compared with 0.92+/-0.32 mm, P=0.001). Combined two- and three-dimensional ICUS produced accurate dissection length (6.13+/-2.29 mm compared with 6.54+/-2.42 mm, P=0.09) and depth (0.86+/-0.32 mm compared with 0.92+/-0.32 mm, P=0.28) estimations.

CONCLUSION

Computerized three-dimensional reconstruction of ICUS images provides improved accuracy compared to conventional ICUS imaging in the detection and quantitation of arterial dissection. This technique would be a useful adjunct to angiography for the precise assessment of vascular injury following PTCA.

The effects of vasodilators on the relaxation of guinea-pig aorta during acute recoil

BACKGROUND

We have investigated the effects of various vasodilators on smooth muscle relaxation during acute recoil with guinea-pig aorta to find effective therapies to prevent acute recoil at percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Muscle strips from guinea-pig aorta without endothelium were placed in a bath filled with modified Krebs solution. The strip was isotonically stretched with a tension of 9 mN for 1 min, and then isometric tension was measured until the tension reached a steady state. Various vasodilators were applied during isometric tension measurement.

RESULTS

When no drug was applied (control), isometric tension reached a steady state within 20 min. The steady state was approximately 10% lower (more relaxed) than the stretched level. When isosorbide dinitrate (ISDN, 1 mM) was applied during isometric measurement, 18.7+/-5.3% greater relaxation occurred than in control relaxation (P<0.05, n=5). When nicorandil (1 mM) was applied, the following relaxation was 18.6+/-5.7% greater than control (P<0.05, n=8). The simultaneous application of glibenclamide (1 mM) completely inhibited such additional relaxation by nicorandil. Application of nifedipine (10 microM) caused a 12.9+/-2.5% greater relaxation than control (P=0.066, n=4). The first metabolite of sarpogrelate (BP984, 10 microM) caused much greater relaxation than control (23.7+/-7.9%, P<0.05, n=6). Amlodipine (10 microM), phentolamine (10 microM), and sarpogrelate (10 microM) had no influence on the relaxation of the strip.

CONCLUSIONS

ISDN, nicorandil and BP984 significantly increase relaxation of the muscle strips after stretching compared to the control. These vasodilators may reduce acute recoil of the smooth muscle after PTCA.

Incidence, morphology, angiographic findings, and outcomes of intramural hematomas after percutaneous coronary interventions: an intravascular ultrasound study

BACKGROUND

Intramural hematomas during percutaneous coronary intervention (PCI) have not been well studied.

METHODS AND RESULTS

We used intravascular ultrasound to determine the incidence, morphology, and clinical features of post-PCI intramural hematomas. In 905 patients with 1025 consecutive native coronary artery, non-in-stent restenosis lesions undergoing PCI, 72 hematomas were detected in 69 arteries in 68 patients. The incidence of intramural hematomas per artery was 6.7% (69 of 1025); 36% (26 of 72) involved the proximal reference artery, 18% (13 of 72) were confined to the lesion, and 46% (33 of 72) involved the distal reference artery. The entry site from the lumen into the hematoma was identified in 86% of hematomas (62 of 72) and had the appearance of a dissection into the media. Conversely, a re-entry site was identifiable in only 8% (6 of 72). The axial extension of the hematoma was distal in 63% and proximal in 37%. In 60% of the hematomas (42 of 72) the angiogram had the appearance of a dissection; in 11% (8 of 72), it appeared to be a new stenosis; and in 29% (22 of 72), no significant abnormality was detected. Non-Q-wave myocardial infarctions occurred in 26% of patients (17 of 65). In 3 patients, the creatine kinase-MB was not measured during the hospital stay. Repeat revascularization occurred in 2 patients in-hospital, 2 additional patients at 1 month, and 8 additional patients at 1 year. There were 3 sudden deaths at 1 year.

CONCLUSIONS

Intravascular ultrasound identified intramural hematomas after 6.7% of PCIs. The mechanism appeared to be a dissection into the media where blood accumulated because of a lack of re-entry. A third of ultrasound-identified hematomas showed no angiographic abnormalities. There was a high rate of non-Q-wave myocardial infarction, need for repeat revascularization, and sudden death in patients with hematomas.

Quantification of elastic recoil after balloon angioplasty in the iliac arteries

PURPOSE

Elastic recoil of the arterial wall has been shown to be responsible for a significant loss of luminal area after balloon angioplasty in the coronary arteries, but it has not been well studied in the peripheral arteries. Because elastic recoil depends on the presence of elastin in the arterial wall, and the amount of elastin varies by artery and proximity to the aorta, the importance of this response to angioplasty may be different in peripheral arteries. The purpose of this study is to document the degree of elastic recoil in the iliac arteries, and analyze variables that might influence the results.

MATERIALS AND METHODS

A series of 19 patients with 25 iliac artery stenoses underwent balloon angioplasty followed by placement of a Palmaz stent with the same-sized angioplasty balloon. The minimum luminal diameter of the lesion was measured before treatment, immediately after balloon angioplasty, and again after stent placement. The arterial diameter after stent placement was defined as the diameter of the inflated balloon. The degree of recoil was correlated with nine variables: patient age and sex, lesion location and length, lesion severity (as percent stenosis), the balloon:artery ratio, and three factors related to lesion morphology--complex versus simple, eccentric versus concentric, and calcified versus noncalcified.

RESULTS

Elastic recoil averaged 36% +/- 11% and ranged from 19% to 54% in this series of patients. The only variable that significantly influenced the degree of elastic recoil was the balloon:artery ratio (P =.039), which was directly related.

CONCLUSION

Elastic recoil is a significant limitation of balloon angioplasty in the iliac arteries. This study illustrates the importance of techniques that limit recoil, such as vascular stents, in angioplasty of the iliac arteries.

Local arterial responses to 32P beta-emitting stents

PURPOSE

32P beta-emitting stents reduce neointimal growth in rabbit iliac arteries for at least 12 months after deployment but are associated with incomplete healing. The aim of this study was to quantitate arterial cellularity, with emphasis on the inflammatory response following radioactive stenting.

METHODS

32P beta-emitting stents were placed in rabbit iliac arteries and analyzed at 3 months (6 and 24 microCi), and 6 and 12 months (6, 24, and 48 microCi). Arterial cellular proliferation and cell densities of smooth muscle cells (SMC), mononuclear cells (macrophages and lymphocytes), and neutrophils (PMN) were determined.

RESULTS

Total intimal cell density was greatest in control stents at all three time points, composed mostly of SMCs. SMC density associated with radioactive stents increased from 3 to 12 months but was significantly less than control nonradioactive stents. There was a 4-fold increase in cellular proliferation in the 24 and 48 microCi group vs. control stents. In the media, SMC density of radioactive stent groups was significantly reduced vs. control stents at all three time points, for all three activities. At 3, 6 and 12 months, there was a dose-dependent increase in intimal inflammatory cell density, which consisted mostly of macrophages. For 6-microCi stents inflammation peaked at 3 months and decreased thereafter. Inflammation for 24-microCi stents peaked at 6 months and then decreased at 12 months. Inflammation associated with 48-microCi stents remained high at 6 and 12 months. Focal atherosclerotic change was seen in 11% of stents in the 24-microCi group, and 37% and 50% in the 48-microCi group at 6 and 12 months, respectively.

CONCLUSION

Intimal SMC density remains suppressed out to 12 months after placement of 32P beta-emitting stents. However, inflammation and cell proliferation remain increased and may potentially result in greater neointimal formation over time.

Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

In the EPIC trial, high-risk patients received the integrin receptor antagonist abciximab v placebo during and for 12 h following percutaneous coronary intervention with a significant 23% decrease of repeat revascularisation at 6 months. However, EPILOG and CAPTURE trials could not confirm these promising long-term results. Recently presented data from the EPISTENT trial suggested a beneficial effect of abciximab on restenosis in patients with diabetes. Based on these divergent results the aim of this study was to test whether alpha v beta 3 receptor blockade by abciximab could cause inhibition of human coronary smooth muscle cell (hcSMC) proliferation, migration, and invasion which represent crucial steps during restenosis development. In contrast to quiescent hcSMCs, proliferating cells were capable to migrate towards chemoattractive stimuli and even capable to invade through a basement membrane equivalent. Abciximab and LM609, an alpha v beta 3 specific inhibiting antibody, caused only a modest dose-dependent inhibition of hcSMC proliferation. On the contrary, the chemotactic and invasive potential of hcSMCs was significantly inhibited by abciximab administration 24 h prior to and during migration. (IC(50)=33.0 microg/ml for chemotaxis and IC(50)=0.5 microg/ml for invasion). For LM609 similar results were obtained. Administration of the drugs just during migration without pretreatment inhibited migration equally but invasion to a lower extent (abciximab: IC(50)=32.6 microg/ml for chemotaxis and IC(50)=44.9 microg/ml for invasion; LM609 IC(50)=3.1 microg/ml for chemotaxis and IC(50)=2.0 microg/ml for invasion). The attachment to the extracellular matrix proteins collagen I, collagen IV, laminin and vitronectin was not influenced. Pretreatment for 24 h with abciximab or LM609 did not cause a downregulation of the alpha v beta 3-integrin receptor. The results of this study indicate that the alpha v beta 3 antagonist abciximab is a potent inhibitor of hcSMC migration and invasion which could explain the observed lower reintervention rate after PTCA and stent implantation.

Vascular repair after balloon overstretch injury in porcine model effects of intracoronary radiation

OBJECTIVES

The purpose of this study was to evaluate the effect of IR on thrombus formation and dissection repair following overstretch balloon injury in porcine coronary arteries.

BACKGROUND

Exposure of blood to the injured arterial wall after percutaneous transluminal coronary angioplasty (PTCA) induces thrombus formation and inflammation in the dissection plane. Neointima formation is related to smooth muscle cell (SMC) proliferation and migration into the preformed thrombus. Intracoronary radiation (IR) with doses of 10 to 25 Gy using either beta or gamma emitters can prevent neointima accumulation by reducing SMC proliferation. However, there are some indications that IR may delay the process of dissection repair after PTCA. The purpose of this study was to evaluate the effect of IR on thrombus formation and dissection repair after overstretch balloon injury in porcine coronary arteries.

METHODS

Forty porcine coronaries were injured by balloon overstretch followed by either 0 or 18 Gy of 90Y prescribed to 1.2 mm from the balloon center. The animals were euthanized 14 days after treatment, and intimal area (IA) and IA corrected for medial fracture length (IA/FL) were quantified by digital image analysis. Dissections were quantified by tracing the length, thickness and area behind the dissection flap. The rate of dissections was calculated for each group. Thrombi were identified and designated as intraluminal thrombus or thrombus within dissection planes (mural thrombus), and area measurements were obtained.

RESULTS

The irradiated group showed a significant reduction of IA/FL (0.55 +/- 0.29 vs. 0.05 +/- 0.09; p < 0.001). No difference was observed in the rate of dissection between control and irradiated arteries (77% vs. 88%, respectively). The control group showed a smaller dissection area (0.19 +/- 0.28 mm2 vs. 0.32 +/- 0.29 mm2; p < 0.05) with smaller mural thrombi (0.03 +/-0.01 mm2 vs. 0.29 +/- 0.30 mm2; p < 0.001). A strong correlation between dissection area and neointima area was observed only in the control group (R2 = 0.474; p < 0.003; alpha0.05 = 0.862). A positive correlation between mural thrombus and dissection area was observed only in the irradiated group (R2 = 0.889; p < 0.001; alpha0.05 = 1.00).

CONCLUSIONS

These results suggest that the dissection area may be a useful parameter by which to quantify the extent of injury and repair after IR and may indicate an incomplete healing process after IR at this time point.

Effects of local delivery of trapidil on neointima formation in a rabbit angioplasty model

1. Smooth muscle cell (SMC) proliferation can result in luminal reduction of a vessel following balloon angioplasty. This study was designed (i) to determine if local administration of trapidil (triazolopyrimidine) into a vessel wall reduces neointima formation, and (ii) to explore the mechanism involved in the subsequent reduction in cell proliferation. 2. Following balloon angioplasty in 40 anaesthetized New Zealand White rabbits, trapidil (50-200 mg) or its vehicle (saline) was injected into the dilated vessel wall of the right femoral artery. Experimental groups and time of investigation: (I) vehicle (2 weeks, n = 3), (II) trapidil-100 mg (2 weeks, n = 3), (III) vehicle (3 weeks, n = 8), (IV) trapidil-50 mg (3 weeks, n = 5); (V) trapidil-100 mg (3 weeks, n = 9) or (V) trapidil-200 mg (3 weeks, n = 7). 3. After 2 weeks, there was a significant reduction of intimal hyperplasia (expressed as intima to media area ratio) in the trapidil group compared with vehicle (0.44 +/- 0.04 vs 0.93 +/- 0.04, *P < 0.05) and also a significant reduction in cell proliferation (% ratio of BrdU-positive cells to total cell number: vehicle 14 +/- 2% vs trapidil 6 +/- 1%, *P < 0.05). 4. After 3 weeks, there was a dose-dependent reduction of intimal hyperplasia in the trapidil groups compared with vehicle (trapidil 50 mg 1.14 +/- 0.04; trapidil 100 mg 0.91 +/- 0.09*; trapidil 200 mg 0.77 +/- 0.09* vs vehicle 1.67 +/- 0.23, *P < 0.05). 5. Thus, the local administration of trapidil to the rabbit femoral artery reduces the neointima formation, which occurs 2 or 3 weeks after balloon angioplasty via a mechanism, which is dependent on inhibition of cell proliferation.

Five-Year Follow-Up of the Medicine, Angioplasty, or Surgery Study (MASS)

Background —Although coronary angioplasty and myocardial bypass surgery are routinely used, there is no conclusive evidence that these interventional methods offer greater benefit than medical therapy alone. This study is intended to evaluate, in a prospective, randomized, and comparative analysis, the benefit of the 3 current therapeutic strategies for patients with stable angina and single proximal left anterior descending coronary artery stenosis.

Methods and Results —In a single institution, 214 patients with stable angina, normal ventricular function, and severe proximal stenosis (>80%) on the left anterior descending artery were selected for the study. After random assignment, 70 patients were referred to surgical treatment, 72 to angioplasty, and 72 to medical treatment. The primary end points were the occurrence of acute myocardial infarction or death and presence of refractory angina. After a 5-year follow-up, these combined events were reported in only 6 patients referred to surgery as compared with 29 patients treated with angioplasty and 17 patients who only received medical treatment ( P =0.001). However, no differences were noted in relation to the occurrence of cardiac-related death in the 3 treatment groups ( P =0.622). No patient assigned to surgery needed repeat operation, whereas 8 patients assigned to angioplasty and 8 patients assigned to medical treatment required surgical bypass after the initial random assignment. Surgery and angioplasty reduced anginal symptoms and stress-induced ischemia considerably. However, all 3 treatments effectively improved limiting angina.

Conclusions —Bypass surgery for single-vessel coronary artery disease is associated with a lower incidence of medium-term and long-term events as well as fewer anginal symptoms than that found in the patients who underwent angioplasty or medical therapy. In this study, coronary angioplasty was only superior to medical strategies in relation to the anginal status. However, the 3 treatment regimens yielded a similar incidence of acute myocardial infarction and death. Such information should be useful when choosing the best therapeutic option for similar patients.

Histopathology of postpercutaneous transluminal coronary angioplasty remodeling in human coronary arteries

BACKGROUND

We studied the histomorphometric correlates of long-term successful coronary balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]). Restenosis after PTCA may occur secondary to the failure of compensatory arterial enlargement or post-PTCA arterial constriction. The histopathology of this process in human subjects remains poorly defined.

METHODS

Forty-two coronary segments from 41 patients treated with PTCA 60 +/- 58 weeks before death were studied. The histomorphometric findings at the PTCA site were compared with those obtained at a proximal reference site.

RESULTS

Histologic long-term success was seen in 18 (43%) of 42 arteries. Histologically successful PTCA arteries (PTCA site lumen of >/=50% of the reference lumen) demonstrated a larger acute lumen, smaller plaque size (normalized to the internal elastic lamina area), and thinner adventitia compared with histologic failures. Relative to the reference sites, histologically successful PTCA showed expansion of the external elastic lamina. In contrast, histologic failures showed a reduced external elastic lamina area, suggesting constrictive remodeling. Neointimal area correlated with the extent of internal elastic lamina disruption, but neither variable was related to histologic PTCA success or failure.

CONCLUSIONS

These data provide histomorphometric confirmation of the hypothesis that constrictive remodeling, not neointimal formation, determines the long-term outcome of PTCA.

Changes of hemostasis, endogenous fibrinolysis, platelet activation and endothelins after percutaneous transluminal coronary angioplasty in patients with stable angina

OBJECTIVES

This study investigated parameters of endogenous fibrinolysis, activation of coagulation and platelets, and endothelin levels before and after elective percutaneous transluminal coronary angioplasty (PTCA) in patients with stable coronary artery disease (CAD).

BACKGROUND

Abrupt vessel closure is a serious short-term complication after PTCA and is often unforeseeable. Detailed insight into the effect of PTCA on hemostasis, platelets and the release of vasoconstrictive substances, which are among the mainly discussed mechanisms of abrupt vessel closure, is needed to enhance the safety of coronary intervention.

METHODS

Plasma levels of markers of platelet activity, coagulation, endogenous fibrinolysis and endothelins were determined in 20 patients with stable CAD undergoing elective PTCA. The blood specimens were drawn before, immediately after, 1 h after intervention and on the next morning.

RESULTS

All patients showed an initially uncomplicated PTCA. Regarding the efficacy of anticoagulation after receiving 15.000 IU heparin during PTCA, two groups were compared. In eight patients with ineffective anticoagulation production of thrombin and platelet activation directly after and 1 h after PTCA was significantly higher compared with 12 patients with effective anticoagulation. Despite the strong activation of coagulation, only a low fibrinolytic response could be observed. Endothelins rose significantly after PTCA in both groups but stayed longer on higher levels in patients with distinct thrombin generation. Three of the eight patients without sufficient heparin treatment suffered abrupt vessel closure.

CONCLUSIONS

Initially uncomplicated dilation of coronary arteries leads to systemically measurable activation of coagulation and platelets in patients with ineffective doses of heparin and release of endothelins in all patients. Therefore, individual adjustment of anticoagulation and platelet inhibition in combination with effective antivasospastic substances are needed in every patient before, during and after initially uncomplicated PTCA to prevent this serious complication.

The effect of antiplatelet drugs, heparin, and preanalytical variables on platelet function detected by the platelet function analyzer (PFA-100)

The platelet function analyzer (PFA)-100 is a newly developed instrument that provides a rapid, in vitro, quantitative measurement of platelet adhesion and aggregation in whole blood flowing through a small aperture under high shear conditions. Thirty patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and ten normal individuals were included in this study. In vitro and in vivo studies were conducted to discern the effect of combinations of antiplatelet drugs (aspirin, ticlopidine, abciximab) and heparin on the performance of the device as well as the effects of preanalytical variables, such as method of sample collection and ex vivo anticoagulants. Studies were also conducted examining the effect of aperture size (standard 150 microns vs. smaller 120 microns) on the ability of the device to detect the effect of antiplatelet drugs. There was no difference in mean PFA-100 closure time with citrate versus PPACK anticoagulants or with venipuncture vs. sheath sampling. Closure times did not vary with heparin administration. Closure times were slightly longer for patients taking aspirin plus ticlopidine compared to aspirin alone (p = NS). In contrast adenosine disphosphate (ADP) induced platelet aggregation was significantly less in patients that took aspirin plus ticlopidine vs. aspirin alone (p = .0005). In vitro, there was a dose-dependent increase in closure time for both aperture sizes with increasing abciximab concentration. Although both cartridges showed infinite closure times at an abciximab concentration of 2.25 micrograms/mL, there was a slight benefit to using the 120 microns aperture cartridges at abciximab concentrations of 1.75 to 2.0 micrograms/mL. In ten patients who were followed during abciximab therapy to assess the effect of aperture size, the PFA-100 was able to detect in vivo platelet inhibition by abciximab, but detection of recovery from abciximab-induced platelet dysfunction was slightly better for the PFA-100 with the 120 microns aperture compared to the standard 150 microns aperture collagen/ADP cartridge.

The degree of neointimal formation after stent placement in atherosclerotic rabbit iliac arteries is dependent on the underlying plaque

The purpose of this study was to determine the effects of stent placement on the underlying arterial morphology and the relations of stent-vessel wall interactions with subsequent neointimal formation in an atherosclerotic artery. Seven New Zealand White rabbits with experimentally induced atherosclerosis underwent balloon angioplasty (n = 7) and stent placement after balloon angioplasty (n = 7) in the iliac arteries. Histologic analysis of the treated arteries was performed at 28 days to assess device interactions with the artery and the pattern of the neointimal response. The area within the external elastic lamina of the stented vessels was 66% greater than the arteries with balloon angioplasty alone (p = 0.001) which contributed to a significantly greater late lumen area (3.33 +/- 0.51 mm2 versus 1.33 +/- 0.20 mm2, p = 0.0028). Neointimal thickness was measured at 220 stent wire sites from 21 sections of stented arteries of which 139 (63%) had underlying plaque and 81 (37%) were adjacent to normal media. Rupture of the internal elastic lamina (IEL) occurred at only 9 (11%) of the 81 stent wire sites over normal media. The mean neointimal thickness was 0.16 +/- 0.01 mm lor all stent wire sites. The neointimal thickness was greater at the stent wire sites with underlying plaque (0.23 +/- 0.01 min) than at the stent wire sites adjacent to normal media (0.08 +/- 0.01 mm) or at sites with rupture of the internal elastic lamina (0.16 +/- 0.02 mm, p = 0.0001). The degree of neointimal formation within the stents strongly correlated with the area of the underlying atherosclerotic plaque (r = 0.76, p = 0.0007) and the extent of plaque or medial compression by the struts (r = 0.90, p = 0.006). The present study characterizes stent interactions in a model commonly employed to evaluate novel therapies for the prevention of restenosis. The neointimal response was influenced by the local arterial morphology and correlated with the extent of plaque or medial compression by the stent. These data may be useful for future studies in this model and understanding the mechanism of in-stent restenosis.

Impact of residual plaque burden on clinical outcomes of coronary interventions

In this study, we summarize the role of residual plaque burden, as determined by intravascular ultrasound, on the development of restenosis following percutaneus coronary interventions. Several clinical trials have shown that the amount of residual plaque is a consistent and independent predictor of subsequent restenosis. The impact of residual plaque burden on late lumen loss is particularly augmented by negative vessel remodeling that is commonly seen after balloon angioplasty and atherectomy. However, early evidence suggests that the importance of plaque burden also applies in the context of stenting. The cotreatment of debulking may further improve the long-term outcome of stenting by maximizing an acute lumen gain with less vessel stretching, preventing stent edge problems and possibly reducing the cell source involved in the intimal hyperplastic process. Evaluation of residual plaque burden with on-line intravascular ultrasound could lead to definitive therapies via risk stratification of the treated segments.

Remodeling after directional coronary atherectomy (with and without adjunct percutaneous transluminal coronary angioplasty): a serial angiographic and intravascular ultrasound analysis from the Optimal Atherectomy Restenosis Study

OBJECTIVES

The intravascular ultrasound (IVUS) substudy of OARS (Optimal Atherectomy Restenosis Study) was designed to assess the mechanisms of restenosis after directional coronary atherectomy (DCA).

BACKGROUND

Recent serial IVUS studies have indicated that late lumen loss after interventional procedures was determined primarily by the direction and magnitude of arterial remodeling, not by cellular proliferation.

METHODS

Complete quantitative coronary angiography (QCA) and IVUS were obtained in 104 patients before and after intervention and during follow-up. All studies were performed after administration of 200 microg of intracoronary nitroglycerin. Angiographic measurements included minimum lumen diameter (MLD), interpolated reference diameter and diameter stenosis (DS). Intravascular ultrasound measurements included lesion and reference external elastic membrane (EEM), lumen and plaque+media cross-sectional area (CSA). The axial location of the lesion site was at the smallest follow-up lumen CSA; the reference segment was the most normal-looking cross section within 10 mm proximal to the lesion but distal to any major side branch. Results are reported as mean +/- one standard deviation.

RESULTS

The QCA reference decreased from 3.51 +/- 0.46 mm to 3.22 +/- 0.44 mm; the MLD decreased from 3.22 +/- 0.47 mm to 2.03 +/- 0.72 mm; and the DS increased from 8 +/- 10% to 38 +/- 20%. On IVUS, the decrease in lumen CSA (from 8.8 +/- 2.5 mm2 to 5.5 +/- 4.0 mm2) was associated with a significant decrease in EEM (from 19.7 +/- 5.6 mm2 to 16.9 +/- 6.2 mm2); there was no significant increase in P+M (from 10.9 +/- 4.2 mm2 to 11.3 +/- 3.9 mm2). A change in lumen correlated with a change in EEM (r = 0.790, p < 0.0001), not with a change in P+M (r = 0.133, p = 0.2258). A decrease in reference EEM (from 19.1 +/- 7.7 mm2 to 17.6 +/- 8.0 mm2) also correlated with a decrease in lesion EEM (r = 0.665, p < 0.0001). Results in restenotic lesions were similar.

CONCLUSION

Restenosis after optimal DCA is caused primarily by a decrease in EEM CSA that extends into contiguous reference segments.

Intravascular ultrasound predictors of restenosis after balloon angioplasty of the femoropopliteal artery

OBJECTIVES

To determine intravascular ultrasound parameters related to restenosis following percutaneous transluminal balloon angioplasty (PTA) of the femoropopliteal artery.

DESIGN

Prospective study.

MATERIALS AND METHODS

Patients were studies with intravascular ultrasound before and after angiographic successful PTA (n = 114). Intravascular ultrasound cross-sections obtained with 1 cm interval in the dilated segment were analysed. A distinction was made between anatomic (duplex scanning) and clinical (Rutherford criteria) restenosis assessed within 1 month and at 6 months after PTA.

RESULTS

Intravascular ultrasound predictors of 1 month anatomic outcome were lumen area stenosis after PTA, lumen area increase, plaque area decrease, and area stenosis decrease; predictor of 6 months anatomic outcome was area stenosis after PTA. Multivariate analysis revealed that area stenosis after PTA was the only independent predictor of both 1 and 6 months anatomic outcome. Intravascular ultrasound predictors of 1 month clinical outcome were the presence of hard lesion and the mean arc of hard lesion. Multivariate analysis revealed that the mean arc of hard lesion was the only independent predictor of 1 month clinical outcome. No predictors for 6 months clinical outcome were found.

CONCLUSIONS

Intravascular ultrasound can elucidate parameters predictive of restonosis after PTA. The strongest intravascular ultrasound parameter predictive of anatomic restenosis was a large area stenosis after PTA.

Failure of intravascular ultrasound to predict dissection after balloon angioplasty by using plaque characteristics

Intravascular ultrasound (IVUS) is more sensitive than angiography in the assessment of plaque characteristics before intervention and vascular damage after balloon angioplasty. On the basis of IVUS data, this finding may improve clinical treatment by reducing the incidence of severe dissections after balloon angioplasty. We therefore studied the relation between plaque characteristics and dissections after balloon angioplasty. First, an in vitro study on atherosclerotic arteries (n = 42) was performed in which IVUS images were compared with histologic sections to validate the IVUS technique; second, the in vitro findings were compared with IVUS findings obtained in vivo (n = 73). Dissections were observed in 37 histologic sections and visualized on IVUS in 22 (59%) of the corresponding ultrasonic cross-sections; in vivo dissections were demonstrated by IVUS in 46 (63%) cases. Dissections were generally seen at the thinnest region of the plaque on both histologic sections (92%) and IVUS cross-sections (in vitro 83%; in vivo 93%). No significant relation was found between pre-interventional plaque characteristics such as composition features and eccentricity and the incidence, location, and extent of postinterventional dissections. Thus IVUS is able to identify dissections after balloon angioplasty, generally occurring at the site of the thinnest plaque diameter. However, neither the incidence nor the severity of these dissections was related to any of the preinterventional plaque characteristics.

Influence of coronary atherosclerotic remodeling on the mechanism of balloon angioplasty

OBJECTIVES

Intracoronary ultrasonography was used to assess coronary arteries before and after balloon percutaneous transluminal coronary angioplasty (PTCA) to determine whether the mode of coronary atherosclerotic remodeling affects the mechanism of balloon dilation.

BACKGROUND

Coronary arteries may enlarge or shrink in response to atherosclerotic plaque development. The effect of coronary remodeling on the mechanism of balloon PTCA has not yet been studied.

METHODS

Forty-one patients with 47 native de novo coronary artery lesions were studied with a 30 MHz intracoronary ultrasound catheter before and after balloon PTCA. Images were analyzed at the lesion site and the adjacent reference segments. At each site the lumen, vessel, and plaque area and the percent area stenosis were measured. Lesions were separated into two groups based on relative vessel area (lesion vessel area/reference vessel area). A relative vessel area >1.0 defines adaptive enlargement (group 1, n = 25), whereas a relative vessel area < or =1.0 reflects coronary shrinkage (group 2, n = 22). Regression analysis examined whether elastic recoil and the PTCA balloon/vessel area ratio correlated.

RESULTS

After balloon PTCA was performed, both the enlargement and shrinkage groups had similar gains in luminal area (2.3 +/- 1.8 mm2 [mean +/- SD] vs 2.8 +/- 1.7 mm2, p = 0.32), reduction in percent stenosis (-19.2% +/- 11.5% vs -14.4 +/- 12.7, p = 0.18), and final lumen area (4.9 +/- 1.7 mm2 vs 4.7 +/- 1.9 mm2, p = 0.73). However, the mechanism of luminal enlargement was different in each group. Reduction in plaque area was significantly greater in the enlargement group (group 1, -2.0 +/- 1.7 mm2 vs group 2, 0.04 +/- 2.2 mm2; p = 0.001), whereas increased vessel area was more important in the shrinkage group (group 1, 0.8 +/- 1.5 mm2 vs group 2, 2.4 +/- 2.3 mm2; p = 0.009). Positive correlation was seen between elastic recoil and the balloon/vessel area ratio in lesions with vessel enlargement (r = 0.80, p < 0.0001). No such correlation was observed in shrinkage vessels (r = 0.28, p = 0.21 ).

CONCLUSIONS

The acute luminal gain after balloon PTCA is similar regardless of the type of coronary remodeling. However, the mode of remodeling affects the mechanism of balloon dilation such that enlargement vessels exhibit plaque compression, whereas shrinkage arteries demonstrate vessel stretch. The post-PTCA elastic recoil correlates linearly to the balloon/vessel area ratio in arteries that have undergone adaptive enlargement.

Regional remodeling of atherosclerotic arteries: a major determinant of clinical manifestations of disease

In this review we present the current data on remodeling, based on in vivo ultrasound imaging or postmortem histologic analysis of native peripheral and coronary arteries from animal models and studies in patients (coronary artery saphenous vein bypass grafts, lesions of restenosis after balloon angioplasty and other catheter-based interventions). Histologic and ultrasound imaging studies of arteries with atherosclerosis and after vascular injury reveal that arterial remodeling is common and that the cross-sectional area of the vessel is not constant. Compensatory enlargement, inadequate compensatory enlargement and shrinkage at the site of atherosclerotic lesions occurs in coronary and peripheral arteries. Current studies demonstrate that arterial remodeling is a major determinant of vessel lumen size.

Abrupt vessel closure: changing importance, management, and consequences

Percutaneous coronary interventions have been performed for 20 years. Despite the success and progress of these interventions, abrupt vessel closure has been a dramatic adverse event of coronary interventions. Closure has frequently led to the major complications of death, myocardial infarction, and emergency coronary artery bypass. Because of the fear of this adverse event and its subsequent complications, the applicability of coronary interventions is sometimes limited. The pathologic characteristics of abrupt vessel closure have been recognized as predominantly caused by dissection, with vessel recoil and thrombus formation playing important secondary roles. The recognition of the lesions at risk for abrupt vessel closure has led to a strategy of lesion-specific device therapy to reduce complications. Similarly the role of antiplatelet and antithrombotic therapies have reduced complications. The earliest methods of dealing with abrupt closure was emergency coronary artery bypass surgery with significant rates of morbidity and mortality. With the advent of second-generation devices and techniques, particularly stents, the management of abrupt vessel closure has been simplified and alternatives to emergency coronary bypass are more available. This article will review the history and current status of the prevention and management of abrupt vessel closure and demonstrate that anticipation and management of this complication have been facilitated with reduction of subsequent complications and increased applicability of coronary interventions.

Endoluminal local delivery of PCNA/cdc2 antisense oligonucleotides by porous balloon catheter does not affect neointima formation or vessel size in the pig coronary artery model of postangioplasty restenosis

Localized delivery of antisense oligonucleotides directed against cell cycle regulatory proteins has been proposed as a means to prevent restenosis after angioplasty. To test whether single endoluminal delivery of a combination of proliferating cell nuclear antigen (PCNA) and cell-division cycle 2 kinase (cdc2) antisense might affect restenosis, we delivered 2 ml of lipid-complexed PCNA/cdc2 antisense oligomers (1.35 mg) to the coronary arteries of pigs after balloon overstretch angioplasty (AS group) and performed planimetric histomorphometry on arterial sections of the tissue, harvested at 4 wk. Compared with controls receiving 3'-5' reversed sequence oligomers (REV group), there were no differences in absolute intimal area (AS 1.36 +/- 0.08 mm2, REV 1.23 +/- 0.10 mm2, P = NS), intimal area normalized to extent of injury (AS 0.67 +/- 0.03, REV 0.77 +/- 0.10, P = NS), or vessel perimeter (AS 7.72 +/- 0.19 mm, REV 7.36 +/- 0.22 mm, P = NS). We conclude that single endoluminal delivery of antisense against key cell cycle regulatory proteins does not affect neointima formation or vessel size in this model of restenosis.