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Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Anvar Babaev has an investigator’s agreement with Cardiovascular Systems, Inc (CSI). Akiko Maehara is employed at the Cardiovascular Research Foundation, which receives funding from CSI. Brad Martinsen is employed by CSI.

Coronary artery injury is a rare complication following blunt chest trauma (BCT), and can be fatal. Here we report findings on postmortem selective coronary angiography of right coronary artery rupture after an assault involving blunt trauma to the chest. A woman in her 60s died after her son stomped on her chest. There were no appreciable signs of injury on external examination, and cause of death could not be determined by postmortem computed tomography (PMCT). Internal findings indicated that an external force had been applied to the anterior chest, as evidenced by subcutaneous hemorrhage and pericardial and cardiac contusions. Postmortem coronary angiography revealed irregularity of the intima and of the fat tissue surrounding the proximal part of the right coronary artery associated with a local filling defect. Histopathological examination suggested coronary rupture with dissection of the tunica media and compression of the lumen cavity. The key points in the present case are that no fatal injuries could be determined on external examination, and the heart and coronary artery injuries were not evident on PMCT. Criminality might be overlooked in such cases, as external investigation at the crime scene would be inadequate and could result in a facile diagnosis of cause of death. This is the first report of coronary artery rupture with dissection that was detected by CT coronary angiography, and provides helpful findings for reaching an appropriate decision both forensically and clinically.

Purpose: To investigate the impact on restenosis rates of deep injury to the adventitial layer during directional atherectomy., Methods: Between 2007 and 2010, 116 consecutive patients (mean age 69.6 years; 56 men) with symptomatic femoropopliteal stenoses were treated with directional atherectomy at a single center. All patients had claudication and TASC A/B lesions in the superficial femoral or popliteal arteries. Histopathology analysis of atherectomy specimens was performed to identify adventitial injury. Clinical follow-up included physical examination and duplex ultrasound scans at 3, 6, and 12 months in all patients. The primary endpoint was the duplex-documented 1-year rate of restenosis, which was determined by a peak systolic velocity ratio <2.4. Patients were dichotomized by the presence or absence of adventitial or medial cuts as evaluated by histopathology., Results: Adventitial injury were identified in 62 (53%) of patients. There were no differences in baseline demographic and clinical features (p>0.05), lesion length (58.7±12.8 vs 56.2±13.6 mm, p=0.40), or vessel runoff (1.9±0.6 vs 2.0±0.6, p=0.37) between patients with and without adventitial injury, respectively. The overall 1-year incidence of restenosis was 57%, but the rate was significantly higher (p<0.0001) in patients with adventitial or medial injury (97%, 60/62) as compared with those without (11%, 6/54)., Conclusion: Lack of adventitial injury after atherectomy for femoropopliteal stenosis is strongly related to patency at 1 year., (© The Author(s) 2015.)

A subset of coronary arterial dissections is associated with eosinophilic coronary periarteritis (ECPA); however, the pathogenesis of the process remains unclear. Mast cells normally reside in coronary arterial adventitia and are known mediators of eosinophilic inflammatory conditions such as type I hypersensitivity reactions. We report two cases in which coronary arterial dissection with ECPA was detected at autopsy. Tryptase, CD68, CD4, CD8, and CD1a immunohistochemical staining was performed to better characterize inflammation. While eosinophils represented a prominent periadventitial inflammatory cell, there were slightly more lymphocytes: CD4/CD8 ratios were within expected reference ranges. There were moderate numbers of macrophages, and few neutrophils or dendritic cells. Numbers of mast cells in dissected versus nondissected sections were compared: adventitial mast cell densities were threefold higher in dissected portions and showed a trend toward increased degranulation. These findings suggest that mast cells may play a role in orchestrating inflammation in cases of ECPA., (© 2015 American Academy of Forensic Sciences.)

Objective: The dynamic expressions of monocyte chemo attractant protein-1 (MCP-1) and CC chamomile receptor 2 (CCR2) after balloon injury and their effects in intimal proliferation were discussed. In this study, the expression of MCP-1 and its receptor during the intimal proliferation in rat artery after balloon injury were studied., Methods: Using the model of balloon injury of rats' arteries, the changes of intimal proliferation were observed with optical microscopy and the expressions of MCP-1 and CCR2 at different times were examined with the methods of RT-PCR and immunohistochemistry. The expressions of MCP-1 and CCR2 in the arterial tissues were detected using reverse transcription polymerase chain reaction (RT-PCR) and analyzed by semi-quantitative method., Results: The expressions of MCP-1 and CCR2 mRNA began to gradually increase after balloon injury. The MCP-1 reached to the peak on the first day, but decreased gradually later on. Expressions of CCR2 mRNA began to increase on the first day and reached to the peak on the 7th day, but then started to decrease gradually until 28th day when we can still detect it. The expressions of MCP-1 proteins began to increase gradually after balloon injury and were obviously detected in the VSMC on the 4th and 7th day, until 14th day when we can still detect it clearly in the proliferating intima., Conclusion: The dynamic expressions of MCP-1, MCP-1 proteins and CCR2 mRNA after balloon injury were shown to play an important role in intimal proliferation.

The aim of this study was to evaluate the diagnostic criteria and to identify the radiological signs (derived from known radiological signs) for the detection of aortic dissections using postmortem computed tomography (PMCT). Thirty-three aortic dissection cases were retrospectively evaluated; all underwent PMCT and autopsy. The images were initially evaluated independently by two readers and were subsequently evaluated in consensus. Known radiological signs, such as dislocated calcification and an intimomedial flap, were identified. The prevalence of the double sedimentation level in the true and false lumen of the dissected aorta was assessed and defined as a postmortem characteristic sign of aortic dissection. Dislocated calcification was detected in 85% of the cases with aortic calcification; whereas in 54% of the non-calcified aortas, the intimomedial flap could also be recognized. Double sedimentation was identified in 16/33 of the cases. Overall, in 76% (25/33) of the study cases, the described signs, which are indicative for aortic dissection, could be identified. In this study, three diagnostic criteria of aortic dissection were identified using non-enhanced PMCT images of autopsy-confirmed dissection cases.

We present two cases of dissection of the thoracic aorta associated with dissection and rupture of the pulmonary artery. In both cases the initial dissection was hypothesized to occur in the thoracic aorta, with secondary dissection and rupture of the pulmonary artery., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

After strangulation, cervical arterial injuries (CAI) are uncommon. We report three unusual cases where strangulation induced immediate stroke. CAI were examined using brain CT scan and Doppler ultrasonography in the three cases and then by autopsy in one of the victims. One of the two victims who survived the attempted strangulation had a unilateral carotid dissection, whereas in the other victim, no arterial dissection or thrombosis was observed. As regards the deceased victim, the autopsy confirmed the bilateral dissection showed on CT scan and Doppler ultrasonic examination and revealed that both carotid arteries were dilated up to two times the normal diameter. Microscopic examination showed a major bilateral hemorrhagic dissection of the media with obliterating fibrous endarteritis lesions associated with inflammatory damage. CT scan with arteriography does not demonstrate all the different types of arterial injury, particularly atheromatous embolism, direct compression, or prolonged spasm. Thus, traditional autopsy remains an essential forensic tool after strangulation to show the type of CAI., (© 2013 American Academy of Forensic Sciences.)

This study is to understand the nature and functional significance of the activated cell death programs and rehabilitation signs during late vascular changes after brain injury. We used light and transmission electron microscopy to describe changes of cells within the vascular endothelium and tunica media of the cortical arteries four weeks after craniocerebral traumatism. Within tunica media of the posttraumatic damaged artery, apoptotic and paraptotic phenotypes were identified as well as some early ultrastructural signs of smooth muscle cells regeneration, these cell highlighting a remarkable degree of plasticity. Surprisingly, some endothelial cells showed an extensive rough endoplasmic reticulum development, whereas other endothelial cells showed typical necrosis. In conclusion, two groups of suicidal cells apoptotic and paraptotic cells were encountered in the same lesional vascular wall after neurotrauma, showing also signs of cell regeneration. The pathophysiologic significance of the coexisting double cell death programs and cell regeneration seems to be in relation with late cell survival, after arterial damage when some cells disappear and other cells try to survive undergoing reversible injury., (Celsius.)

Objective: Proliferation of smooth muscle cells (SMC) in response to vascular injury is central to neointimal vascular remodeling. There is accumulating evidence that histone acetylation constitutes a major epigenetic modification for the transcriptional control of proliferative gene expression; however, the physiological role of histone acetylation for proliferative vascular disease remains elusive., Methods and Results: In the present study, we investigated the role of histone deacetylase (HDAC) inhibition in SMC proliferation and neointimal remodeling. We demonstrate that mitogens induce transcription of HDAC 1, 2, and 3 in SMC. Short interfering RNA-mediated knockdown of either HDAC 1, 2, or 3 and pharmacological inhibition of HDAC prevented mitogen-induced SMC proliferation. The mechanisms underlying this reduction of SMC proliferation by HDAC inhibition involve a growth arrest in the G(1) phase of the cell cycle that is due to an inhibition of retinoblastoma protein phosphorylation. HDAC inhibition resulted in a transcriptional and posttranscriptional regulation of the cyclin-dependent kinase inhibitors p21(Cip1) and p27(Kip). Furthermore, HDAC inhibition repressed mitogen-induced cyclin D1 mRNA expression and cyclin D1 promoter activity. As a result of this differential cell cycle-regulatory gene expression by HDAC inhibition, the retinoblastoma protein retains a transcriptional repression of its downstream target genes required for S phase entry. Finally, we provide evidence that these observations are applicable in vivo by demonstrating that HDAC inhibition decreased neointima formation and expression of cyclin D1 in a murine model of vascular injury., Conclusions: These findings identify HDAC as a critical component of a transcriptional cascade regulating SMC proliferation and suggest that HDAC might play a pivotal role in the development of proliferative vascular diseases, including atherosclerosis and in-stent restenosis.

Aims: Expression of SM22 (also known as SM22alpha and transgelin), a vascular smooth muscle cells (VSMCs) marker, is down-regulated in arterial diseases involving medial osteochondrogenesis. We investigated the effect of SM22 deficiency in a mouse artery injury model to determine the role of SM22 in arterial chondrogenesis., Methods and Results: Sm22 knockout (Sm22(-/-)) mice developed prominent medial chondrogenesis 2 weeks after carotid denudation as evidenced by the enhanced expression of chondrogenic markers including type II collagen, aggrecan, osteopontin, bone morphogenetic protein 2, and SRY-box containing gene 9 (SOX9). This was concomitant with suppression of VSMC key transcription factor myocardin and of VSMC markers such as SM α-actin and myosin heavy chain. The conversion tendency from myogenesis to chondrogenesis was also observed in primary Sm22(-/-) VSMCs and in a VSMC line after Sm22 knockdown: SM22 deficiency altered VSMC morphology with compromised stress fibre formation and increased actin dynamics. Meanwhile, the expression level of Sox9 mRNA was up-regulated while the mRNA levels of myocardin and VSMC markers were down-regulated, indicating a pro-chondrogenic transcriptional switch in SM22-deficient VSMCs. Furthermore, the increased expression of SOX9 was mediated by enhanced reactive oxygen species production and nuclear factor-κB pathway activation., Conclusion: These findings suggest that disruption of SM22 alters the actin cytoskeleton and promotes chondrogenic conversion of VSMCs.

Aims: Transradial coronary intervention (TRI) introduces a trauma to the radial artery (RA), possibly influencing quality as a bypass conduit if subsequently used. We sought to determine the acute and chronic effects of TRI on the RA by optical coherence tomography (OCT)., Methods and Results: Immediately after TRI completion, 73 RAs in 69 patients were examined. The sheath was pulled back 2 cm distal to the puncture site, and OCT imaging was performed. The acute injuries and intimal thickening were compared between first-TRI RAs and repeat-TRI RAs. Intimal tears were observed in 49 RAs (67.1%) and were more frequent in the distal than in the proximal RA (P = 0.001). Medial dissections were not uncommon (26 RAs, 35.6%). The frequency of acute injury was significantly higher in repeat-TRI RAs (P < 0.001). Intima/medial area, the maximum intimal thickness/medial thickness ratio, and per cent narrowing were all significantly greater in repeat-TRI RAs in the distal and proximal RA. Multivariate analysis revealed that a repeated TRI procedure was the only independent predictor of intimal thickening., Conclusion: Optical coherence tomography clearly demonstrated significant acute injuries and chronic intimal thickening of RA after TRI. Further study should evaluate the impact of these effects when TRI RAs are subsequently used as conduits, on long-term graft patency and on clinical outcomes after bypass surgery.

Introduction: Chronic allograft vasculopathy is an important cause of graft loss. Considering the inflammatory response in the development of chronic vascular lesions, therapeutic approaches to target the inflammatory process may be useful. We sought to investigate the possible protective effects on balloon catheter-induced vascular injury of thalidomide and tamoxifen, 2 drugs with powerful anti-inflammatory, immunomodulatory, and antifibrotic effects, using an animal model that mimics the morphologic features of chronic allograft vasculopathy., Methods: Male Wistar rats subjected to balloon catheter carotid injury (INJ) were treated with thalidomide (100 mg/kg), or tamoxifen (10 mg/kg), or vehicle. Contralateral right carotid arteries were used as uninjured controls. Morphometric and immunohistochemical analyses were performed at 14 days postinjury., Results: Injured carotid arteries showed marked neointimal hyperplasia, which was significantly inhibited among animals treated with thalidomide or tamoxifen: neointimal/media ratios of 1.4 +/- 0.4 versus 0.2 +/- 0.1 versus 0.4 +/- 0.2, for INJ, INJ + Thalid, and INJ + Tamox; respectively (P < .001). The endothelial cell loss was significantly less pronounced among animals subjected to carotid balloon injury that were treated with thalidomide (24 +/- 14 vs 1 +/- 1 cells per section in INJ, respectively (P < .05). Therapy with either thalidomide or tamoxifen effectively maintained alpha-smooth muscle actin expression in the media, similar to uninjured arteries. In this setting, tamoxifen was additionally effective to prevent the migration of myofibroblasts in to the intima., Conclusion: Thalidomide and tamoxifen were effective to reduce neointimal hyperplasia secondary to vascular damage. The vasculoprotective effects of thalidomide were more pronounced to preserve endothelial cells, whereas tamoxifen inhibited smooth muscle cell migration and proliferation. A possible beneficial effect of combined therapy with thalidomide plus tamoxifen should be addressed in future studies., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Introduction: Recanalisation rates (20-32%) 1-3 years after truncal vein foam sclerotherapy (FS) suggest thrombotic occlusion rather than irreversible vein wall injury. This study examines the injury inflicted by sodium tetradecyl sulphate (STD) foam before and after balloon endothelial denudation (BD)., Methods: In 20 patients undergoing great saphenous vein (GSV) stripping 1.5 cm proximal GSV were harvested (controls). The next 1.5 cm were harvested after in situ BD (n = 10) or no denudation (n = 10). These test segments were filled with 1% or 3% STD foam (5 min), flushed and fixed in formalin. Percentage endothelial cell loss (ECL) and tunica media injury were determined (H&E staining) and collagen structure assessed (transmission electron microscopy, TEM)., Results: Controls showed no injury. 1% and 3% STD foam caused 86.3% and 92.2% ECL (p < 0.001 versus controls; 1% versus 3%, p = 0.55). Endothelial cells persisted in all sections. BD increased ECL (1%: 96.9%, 3%: 98.1%, p = 0.01) Tunica media injury (smooth muscle vacuolation) was minimal (8.9% (1% STD) and 12% (3% STD) of its depth) and not enhanced by BD (1%: 8.7%, p = 0.93; 3%: 11.3%; p = 0.86). No collagen disruption occurred (TEM)., Conclusions: Balloon denudation increased ECL but did not facilitate tunica media injury. Equivalent injury was inflicted by 1% and 3% STD., (Copyright 2009 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.)

Aim: Almost all cross-clamps utilized in vascular surgery, even atraumatic clamps, have been shown to cause mechanical damage to the vascular wall. In recent years, surgical procedures using an endoluminal balloon technique have been reported as an alternative occlusion strategy. This study discusses the histopathological characteristics and comparison between vascular wall damage secondary to the two occlusion techniques in the early postoperative period., Methods: Twelve adult rabbits were divided into two experimental groups: the clamp group (N. = 6) and the balloon group (N. = 6). External cross-clamp occlusion was applied to the abdominal aorta for 30 minutes via laparotomy in the clamp group. In the balloon group, occlusion was applied for 30 minutes by inflating the catheter balloon, which was inserted through the iliac artery and advanced into the abdominal aorta. The appropriate aortic segments were subsequently extracted in both groups and tissue samples were examined by light and electron microscopy. Finally, the samples were scored for grade of tissue damage., Results: In both experimental groups, tissue damage was apparent. In the investigations carried out under light microscopy, it was observed that the damage caused by balloon occlusion was remarkably less than the damage caused by the cross-clamp technique. In the balloon group, eight tissue samples (66.7%) had grade 1 damage. On the other hand, five tissue samples had grade 3 damage, all of which were in the clamp group. Investigation by electron microscopy revealed that greater intimal, medial, and adventitial damage occurred in the vascular walls of the clamp group samples, and this also corresponded with an increase in immune response and intraluminal thrombosis., Conclusion: External clamp and internal balloon occlusion techniques applied to the aorta were compared, and widespread intimal and medial damage were observed in both techniques. However, endoluminal occlusion of the aorta should be the technique of choice in properly selected cases, since it results in lower damage grades, and it should also be used if application of an external clamp is technically difficult.

Objective: Vascular remodeling is a physiological process that occurs in response to long-term changes in hemodynamic conditions, but may also contribute to the pathophysiology of intima-media thickening (IMT) and vascular disease. Shear stress detection by the endothelium is thought to be an important determinant of vascular remodeling. Previous work showed that platelet endothelial cell adhesion molecule-1 (PECAM-1) is a component of a mechanosensory complex that mediates endothelial cell (EC) responses to shear stress., Methods and Results: We tested the hypothesis that PECAM-1 contributes to vascular remodeling by analyzing the response to partial carotid artery ligation in PECAM-1 knockout mice and wild-type littermates. PECAM-1 deficiency resulted in impaired vascular remodeling and significantly reduced IMT in areas of low flow. Inward remodeling was associated with PECAM-1-dependent NFkappaB activation, surface adhesion molecule expression, and leukocyte infiltration as well as Akt activation and vascular cell proliferation., Conclusions: PECAM-1 plays a crucial role in the activation of the NFkappaB and Akt pathways and inflammatory cell accumulation during vascular remodeling and IMT. Elucidation of some of the signals that drive vascular remodeling represent pharmacologically tractable targets for the treatment of restenosis after balloon angioplasty or stent placement.

Introduction: Vascular intimal hyperplasia is associated with increased mortality and morbidity. The authors investigated the effects of atorvastatin on vascular intimal hyperplasia., Materials and Methods: Rats were divided into 4 groups. Groups 1, 2, and 3 had experimental aortic injury and received intraperitoneal injection of atorvastatin, solvent, or 0.9% NaCl, respectively. Group 4 was a nonintervention (laparotomy only) control group. Animals were sacrificed after 3 weeks. Blood samples and injured aortic segment were analyzed., Results: Atorvastatin administration significantly lowered total and low-density lipoprotein cholesterol levels (P = .012 and P = .001, respectively), intima-media ratio (P = .002), and intimal smooth muscle cell accumulation (P < .05) in group 1. Luminal narrowing in animals in group 1 was significantly lower than that in animals in groups 2 and 3, but was higher than in animals in group 4 (P = .009)., Conclusions: Atorvastatin suppresses intimal hyerplasia and aids in intimal regeneration by lowering blood lipids and intimal smooth muscle cell accumulation.

The authors report a case of restenosis in the bilateral internal carotid arteries (ICAs) following angioplasty for cerebral vasospasm. This 53-year-old woman suffering subarachnoid hemorrhage due to a ruptured posterior communicating artery aneurysm had severe vasospasm and underwent angioplasty of the left and right ICAs and middle cerebral arteries. Two months later, a follow-up CT angiogram revealed bilateral ICA stenoses. Transluminal angioplasty leads to long-term connective tissue damage in the medial and adventitial layers from the disruption of the arrangement of collagen fibers due to stretching and tearing, resulting in loss of transmission of contractile forces. Furthermore, following endothelial cell denudation and stretching and rupture of internal elastic lamina from angioplasty, reendothelialization of the intimal layer composed of smooth muscle cells may also explain the contractile properties of restenosis. Other factors such as macrophage-induced inflammation and reactive oxygen species accumulation may also contribute to restenosis. This is the second reported case of restenosis following angioplasty to treat vasospasm, although restenosis is a known complication of angioplasty for treatment of atherosclerosis. In addition, this is the first case of restenosis in the bilateral ICAs following angioplasty for vasospasm. This report presents an illustrative case study and reviews the pathophysiology of angioplasty and restenosis.

We attempted to establish histopathological identification between traumatic rupture and nontraumatic arterial dissection of the intracranial vertebral artery (IVA) resulting in subarachnoid hemorrhage (SAH). Step-serial observations of ruptured IVAs among four traumatic and 44 nontraumatic SAH patients were investigated. We found that the most specific characteristic for differentiation was the shape of the ruptured adventitia. Extension of the adventitia was clearly observed in nontraumatic cases. In contrast, traumatic cases showed transmural ruptures. Other specific characteristics were also detected. For traumatic cases, small incomplete tears of intima and media were frequently found; they formed oblique tears without adventitial extension. Fragmentized internal elastic lamina was also observed in traumatic cases. In contrast, previous arterial dissections were frequently confirmed in nontraumatic cases. Medial degenerations or defects were detected in all nontraumatic cases. In these cases, the peripheral lesion of the rupture was appeared as intimal tears at recessed vascular wall caused by medial defects. This suggested a relationship between medial lesions and pathogenesis of arterial dissections. These additional features were found in both ruptured and non-ruptured intracranial arteries. We concluded that histopathological investigation is a reliable method for differential diagnosis between traumatic and nontraumatic rupture of the IVA resulting in fatal SAH. These morphological differentiations could be valuable for medicolegal diagnosis.

Objective: The immediate effects of transradial access on the radial artery wall are unknown. In this study we sought to assess the histological changes induced by catheterization on the radial artery., Methods: Thirty-four patients undergoing coronary artery bypass grafting (CABG) had radial arteries harvested to serve as bypass conduits. The proximal and distal ends of the radial artery conduits were sectioned and embedded in paraffin. Both ends of all specimens were evaluated by a blinded pathologist for intimal hyperplasia, medial inflammation, medial calcification, periarterial tissue or fat necrosis, adventitial inflammation, adventitial necrosis, and adventitial neovascularization. Fisher's exact test was used for statistical analysis., Results: Fifteen previously catheterized radial arteries (TRA group) were compared with 19 noncatheterized arteries (NCA group). The distal ends of the TRA group showed significantly more intimal hyperplasia (73.3% vs 21.1%; p = 0.03), periarterial tissue or fat necrosis (26% vs 0%; p = 0.02), and more adventitial inflammation (33.3% vs 0%; p = 0.01) than the distal ends of the NCA group. The distal ends of the TRA group also showed significantly more intimal hyperplasia (73.3% vs 26.6%; p = 0.03) and adventitial inflammation (33.3% vs 0%; p = 0.01) than the proximal ends of the same arteries. There were no histological differences in the proximal ends of the two groups., Conclusion: Transradial catheterization induces significant histological changes suggestive of radial artery injury limited to the puncture site in the form of intimal hyperplasia, medial inflammation, and tissue necrosis. Both the proximal and distal ends of the radial artery show a spectrum of atherosclerotic changes independent of its use for transradial catheterization.

Vascular proliferative diseases are characterized by VSMC proliferation and migration. Kinase interacting with stathmin (KIS) targets 2 key regulators of cell proliferation and migration, the cyclin-dependent kinase inhibitor p27Kip1 and the microtubule-destabilizing protein stathmin. Phosphorylation of p27Kip1 by KIS leads to cell-cycle progression, whereas the target sequence and the physiological relevance of KIS-mediated stathmin phosphorylation in VSMCs are unknown. Here we demonstrated that vascular wound repair in KIS-/- mice resulted in accelerated formation of neointima, which is composed predominantly of VSMCs. Deletion of KIS increased VSMC migratory activity and cytoplasmic tubulin destabilizing activity, but abolished VSMC proliferation through the delayed nuclear export and degradation of p27Kip1. This promigratory phenotype resulted from increased stathmin protein levels, caused by a lack of KIS-mediated stathmin phosphorylation at serine 38 and diminished stathmin protein degradation. Downregulation of stathmin in KIS-/- VSMCs fully restored the phenotype, and stathmin-deficient mice demonstrated reduced lesion formation in response to vascular injury. These data suggest that KIS protects against excessive neointima formation by opposing stathmin-mediated VSMC migration and that VSMC migration represents a major mechanism of vascular wound repair, constituting a relevant target and mechanism for therapeutic interventions.

Aims: To study how the balance between tacrolimus elution and polymer degradation from drug-eluting stents (DES) affects neointimal thickening (NIT) in swine coronary arteries., Methods and Results: We assessed a fast-degrading high dose (2 microg/mm2), a slow degrading low dose (1 microg/mm2) or polymer-only coated DES (Pol) versus bare metal stent (BMS). Coronary segments were pre-injured with a balloon/artery ratio of 1.1 to 1.3. Then stents were implanted at that site with a stent/artery ratio of 1.1, with a follow-up period of 5 to 180 days. Histology showed a well endothelialised neointima (82 +/- 1% in high dose DES vs. 93 +/- 8% in BMS) already at five days, without differences in eNOS expression. Morphometry indicated that neointimal thickness in DES was significantly reduced as compared to BMS and Pol at 28 and 90 days. Polymer degradation products induced a distinct inflammatory response which was effectively suppressed in DES. Between 90 and 180 days, however, the slow degrading low-dose stent showed catch-up of NIT., Conclusions: Tacrolimus eluted from a biodegradable stent coating can suppress the inflammatory effect of the coating degradation products if the balance between the drug levels and the degradation products is favorable.

A marked difference in the healing process of the inferior vena cava in rats following a stab with a 17-G (1.48 mm phi) ultrahard zirconium ceramic (Zr) needle and with a common stainless steel (St) needle (also 1.48 mm phi was observed. This was investigated in vivo by histological imaging and biochemical micro-autoradiographic imaging using [2-(14)C]-thymidine as a biomarker in vivo. On the first day after the stab with either, the Zr or the St injection needle, the tunica adventitia showed the most pronounced damage, as evidenced by a large puncture wound characterized by blood congestion, but with few inflammatory cells being observed. A marked contraction of the tunica media was observed. The depth of the injury reached the tunica layer, but amounted to less than 1/3 of the needle diameter. Loose fragments of the endothelial lining were detected, together with scattered red corpuscles. The survival rate of the experimental animals amounted to less than 40% on the 3rd day after the stab by either the Zr or St needle, due to the large needle diameter. In addition, histological imaging of the wound area in the endothelial layer and tunica media showed considerable congestion and inflammation, which limited the evaluation of the regeneration status of the inferior vena cava of the surviving animals. Results were obtained from a few animals that displayed satisfactory recovery status. On the 3rd day after the stab by either the Zr or St injection needle, a relatively large proportion of the hemostatic clots became incorporated into the collagenous tissue, i.e. the tunica adventitia. A marked contraction of the tunica media was also observed, similar to that on the 1st day, following the needle injury. In the case of the endothelium (tunica intima), the injury caused by the Zr needle was reinfiltrated by adult stem cells 3 days after the stab, but the tunica media, composed of endothelial cells, still contained relatively contracted collagenous material. In addition, several interesting cell colonies were observed in the medial layer at the short distance from the boundary of the damaged tissue. It was assumed that these colonies produced medial tissue composed of collagenous supporting tissue or smooth muscle cells. In the experiment using the St needle, the incorporation of [2-(14)C]-thymidine into the nucleus of the stem cells was observed in the small capillaries of the tunica media, but not in the support cells of the latter.

Background: The short-term results for the prevention of coronary restenosis after intravascular brachytherapy (IVBT) and use of drug-eluting stents (DESs) are excellent. The long-term results either lack or present with late complications (e.g., late thrombosis and late catch-up phenomenon leading to late restenosis even years after the initial procedure). Both IVBT and DESs mediate their potent antirestenotic effects via a cytostatic mechanism, but the cardiovascular pathology at late time points after the use of these antiproliferative therapies is incompletely understood. This study investigated the long-term effects of antiproliferative beta-irradiation in a clinically relevant porcine coronary model to address the pathophysiology of late coronary restenosis after antiproliferative vascular interventions., Methods: We performed percutaneous transluminal coronary angioplasty (PTCA) in two major coronary arteries in 12 domestic crossbred pigs. One of the two balloon-injured segments was randomly assigned to receive immediate beta-irradiation (PTCA+IVBT group) using a noncentered delivery catheter (20 Gy; Novoste Beta-Cath System, Novoste, Norcross, GA, USA). The animals were sacrificed after 14 days (n=6) or 3 months (n=6)., Results: The luminal area in the PTCA+IVBT group decreased significantly 3 months after the intervention as compared with that in the PTCA group (PTCA 3.45+/-0.46 mm2 vs. PTCA+IVBT 1.22+/-0.26 mm2; P=.0017). This lumen loss was primarily due to shrinkage of the external elastic lamina area (negative arterial remodeling; PTCA 5.22+/-0.27 mm2 vs. PTCA+IVBT 3.42+/-0.45 mm2; P=.0064), which was accompanied by an increase in the adventitial area (PTCA 3.07+/-0.2 mm2 vs. PTCA+IVBT 5.41+/-0.5 mm2; P=.0049)., Conclusions: The application of antiproliferative radiation in a porcine coronary model caused an early beneficial effect (reduction of intimal-medial lesion and luminal gain) that was followed by a late lumen loss primarily due to negative arterial remodeling. This mechanism may in part help us understand the pathophysiology of late adverse events occurring after IVBT.

We developed a canine model of arterial dissection and serially observed morphological changes angiographically and histopathologically to clarify the causes and mechanisms resulting in dissecting aneurysm formation or arterial occlusion. Intimal defects of various sizes and shapes were made on the arterial walls to provide an entry zone for dissection, so as to simulate the extent of arterial wall injury. Our experimental model showed angiographic and histopathological changes similar to those in clinical cases. As for our initial findings immediately after lesioning, either a double shadow (pseudolumen) or stenosis of the affected artery, due to compression from the subadventitial hematoma, was observed in the angiograms of all lesions. In some lesions with a pseudolumen, a dissecting aneurysm developed subsequently. Some arteries showing focal occlusion recanalized, and stenosis spontaneously improved. Very small dissections resulted in spontaneous healing, while a large intimal entry zone caused stenotic lesions. However, a medium-sized entry zone (4-6 mm) may induce aneurysm formation. The different features of dissection may be caused by the characteristics of flow into the subadventitial cavity and by thrombogenesis. Morphological changes after arterial dissection were closely related to the extent of intimal injury, suggesting that the size of the intimal entry zone may determine whether or not a dissecting aneurysm is formed.

Background: Percutaneous transluminal angioplasty (PTA) of severely stenotic peripheral vascular lesions is hampered by a higher restenosis rate. The effects of PTA on vascular wall as well as the effects of the antirestenotic properties of endovascular brachytherapy (EVBT) remain unclear. MRI allows in vivo noninvasive assessment of the vascular effects of such treatment strategies. We sought to elucidate the vascular effect of PTA and PTA+EVBT by serial MRI., Methods and Results: Twenty symptomatic patients with severe stenosis of the femoropopliteal artery were randomly assigned to PTA (n=10) or PTA+EVBT (n=10; 14 Gy by gamma-irradiation source) and imaged by high-resolution MRI before and 24 hours and 3 months after intervention. An independent observer blinded to the procedure analyzed the MRI data. At 24 hours, cross-sectional MRI revealed that lumen area (86% and 67%) and total vessel area (47% and 34%) increased similarly in the PTA and PTA+EVBT groups, respectively. All patients showed severe splitting of the atherosclerotic plaque, resulting in an irregularly shaped lumen. At 3 months, MRI revealed a significant difference in lumen area change between the PTA and PTA+EVBT groups (40% and 106%, respectively; P=0.026) and in the total vessel area (14% and 39%, respectively; P=0.018). At 3 months, plaque disruption was still present in 50% of the patients treated with PTA+EVBT., Conclusions: After PTA, there is deep disruption of the atherosclerotic plaques and an extensive remodeling process of the arterial wall. Luminal loss after PTA is partially due to inward vessel remodeling. Brachytherapy prevents inward remodeling and induces an increase in lumen area but partially prevents healing of disrupted vessel surface.

Objectives: In a histopathologic study, we assessed the balance of cell proliferation and apoptosis by counting the number of apoptotic and proliferating cell nuclear antigen-positive cells in freshly harvested atherectomy specimens from 34 patients., Background: Remodeling of human coronary arteries is an adaptive process that alters vascular lumen size., Methods: Intravascular ultrasound was performed prior to atherectomy. Total vessel area (area within the external elastic lamina [EEL]), lumen area and plaque area were measured at the region of interest (ROI), and at a proximal and distal reference segment, utilizing the formula Delta(%)=100x(ROI-reference segment)/reference segment. Positive arterial remodeling (R+) resulting in luminal expansion was defined as DeltaEEL >10%. Absence of remodeling (0 < DeltaEEL <10%) and constrictive arterial remodeling (DeltaEEL <0) were considered as neutral remodeling (R0) and negative remodeling (R-), respectively., Results: In R- lesions, apoptotic indices (APO) were significantly elevated (17.17 +/- 2.19%) compared with R+ lesions (4.89 +/- 1.7%; p = 0.0007). In a rabbit iliac percutaneous transluminal coronary angioplasty model intimal apoptosis was increased four weeks after balloon angioplasty injury (APO 8.8 +/- 0.03%) compared with contralateral untreated segments (APO 3.0 +/- 0.04%, n = 6). Lesions with an EEL/intimal area <3.0 showed significantly more intimal apoptosis than untreated lesions (p = 0.02)., Conclusions: The data indicate that constrictive remodeling of atherosclerotic coronary lesions is associated with increased apoptosis of intimal cells. We speculate that increased apoptosis is due to extensive plaque healing after episodes of symptomatic or asymptomatic plaque rupture.

Background: Surgical and ischemic injury to the artery wall initiates vascular wound-healing responses that stimulate atherosclerotic plaque growth. The plasminogen activators have cellular chemotactic, adhesion, and proteolytic activity. Serp-1 is a secreted myxoma virus glycoprotein serpin that binds and inhibits plasminogen activators. We have examined the effects of Serp-1 on plaque growth and inflammatory cell invasion in animal models after balloon injury and after aortic allograft transplant., Methods: We used histologic analysis to assess 4 animal models of angioplasty-mediated injury and 2 models of aortic allograft transplant for intimal hyperplasia and cellular invasion. We assessed plasminogen activator (uPA and tPA) and inhibitor (PAI-1) expression in rat iliofemoral arteries after balloon injury using Western blot, enzyme activity, and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR)., Results: Plaque growth after balloon injury decreased after Serp-1 treatment in all balloon-injury models tested. Transplant vasculopathy also significantly decreased in 2 rat models of aortic allograft transplant. Infusion of a Serp-1 active site mutant, that lacked plasminogen activator inhibiting activity, did not inhibit plaque growth. Quantitative RT-PCR detected increased transcription of PAI-1 mRNA. Increased PAI-1 protein and enzyme-inhibitory activity was also detected in Serp-1-treated arteries by activity assay and Western blot., Conclusions: Thrombolytic serpins are central regulatory agents in vascular wound-healing responses. Investigation of the inhibitory mechanisms of viral serpins may provide new insights into atherogenesis.

Recent evidence supports a role for cell death and inflammation as etiologic factors in neointimal formation and restenosis after angioplasty. This study was undertaken to examine the pattern and intensity of the proliferative response, cell death, and activation of inflammatory, endothelial and smooth muscle cells (SMC) in a model of intimal reinjury. Two ballooning injuries were performed to rat aorta, the second one 14 days after the first injury. Our results demonstrate that ballooning injury to pre-existing neointima differs clearly from an injury to a normal aorta. First, ballooning injury to pre-existing neointima doubled the proliferative response of SMC and intimal thickening, but proliferation of SMC occurred only in the intima, and did not extend into the media. Second, within four hours after the first injury, the number of TUNEL-positive SMC in the media increased from 3% to 23%, but no such increase was found in the pre-existing neointima after the second injury. Third, the prompt proliferative response of intimal SMC after the second injury was linked with a significant increase in endothelial P-selectin and neointimal VCAM-1 immunoreactivity, compared to the first injury at corresponding time points, followed by high numbers of activated ED3+ macrophages and CD4+ T cells in the developing neointima. A balance in injury-induced cell death and proliferation obviously maintains stable cell numbers observed in the media, whereas in the neointima, the resistance of SMC to injury-induced cell death may contribute to a rapid lesion formation in restenosis.

It is generally believed that injury of the vessel wall is an important condition for the development of atherosclerosis. The nature of this injury and its relationship to lesion origin, however, are not clearly understood. Based on early work by the author and a selective review of the literature, evidence is presented to show how a common cardiovascular event, vasospasm, may be one of the factors responsible for this tissue damage, because it produces a substantial arteriopathy in the very vessel in which it occurs.

We have observed that acute medial cell loss is an initial event in the response to vascular injury induced by balloon-catheter distention of the rabbit carotid artery. Numerous apoptotic medial cells were observed as early as 30 minutes after balloon inflation, and a 70% loss of cellularity was evident by 90 minutes. Balloon injury was associated with oxidative stress as reflected by a fall in glutathione levels by 63% within 30 minutes after injury. We hypothesized that balloon injury activated a redox-sensitive signaling pathway coupled to the regulation of apoptosis. Indeed, the activity of the proapoptotic signal mediator, stress-activated protein kinase, was increased severalfold within 10 minutes after injury. Moreover, modifying the vascular redox state by the administration of 1 of 2 structurally dissimilar antioxidants, N-acetyl cysteine or pyrrolidine dithiocarbamate, markedly attenuated both stress-activated protein kinase activation and the induction of apoptosis at 30 minutes. We hypothesized further that the induction of vascular smooth muscle cell apoptosis is modulated by phenotype. In contrast to medial cells, we observed that neointimal cells were relatively resistant to apoptotic death induced by angioplasty injury. This resistance to balloon injury-induced death was associated with an upregulation of the antiapoptotic mediator bcl-xL. This study suggests that acute apoptotic cell death after vascular injury is a highly regulated process governed by cellular redox state and the relative expression of antiapoptotic genes. Angioplasty-induced vascular cell apoptosis may be an important determinant of vascular remodeling and restenosis.

Ischemia-induced tissue activation may contribute to the pathogenesis of graft vasculopathy, but the mediators implicated have only partially been characterized. To gain further insight into the molecular mechanisms involved, syngeneic rat aortic transplants with cold-storage-induced vasculopathy were studied for differentially expressed mRNA transcripts. Vessel segments were exposed to either 1 or 18 hours of cold ischemia, followed by transplantation into syngeneic recipients. After 3 days or 4 weeks, the grafts were removed and total mRNA was isolated and used for differential display to identify modulation of transcript expression related to prolonged storage. Using 15 sets of random primers, 17 polymerase chain reaction products were up-regulated and 2 were downregulated in grafts exposed to 18 hours of ischemia. Sequencing of these amplicons showed that 6 had a high degree of homology to known sequences whereas 13 had no homology to any of the genes in the database. Two of the differentially displayed amplicons (capping protein and eotaxin) were cloned, re-amplified, and used as probes for Northern blot analysis to confirm their differential expression. Immunohistochemistry using monoclonal antibodies against capping protein-alpha and eotaxin confirmed that both proteins are expressed in the media of normal aortas and that there was an increased expression in vessels exposed to prolonged ischemia albeit that the increase at the protein level seemed less compared with changes in transcript expression. Northern blots with RNA from aortic allografts exposed to prolonged ischemic storage also showed increased levels of capping protein and eotaxin mRNA whereas there was a decrease in the relative amount of these transcripts in vessels exposed to balloon denudation, suggesting that the increase after prolonged ischemic exposure is not the result of a nonspecific response to injury. Based on the biological characteristics of capping protein and eotaxin it is conceivable that they play a pathogenetic role in ischemia-induced vessel wall remodeling. It remains to be established whether these genes or their products serve as target molecules for therapeutic interventions to prevent or treat cold-storage-induced graft vasculopathy.

Background: Injury to the smooth muscle cells of the media affects the remodeling process of vein grafts. The purpose of this study was to determine whether different techniques of surgical preparation influence the degree of medial smooth muscle injury., Methods: Carotid-saphenous vein interposition grafting was performed in crossbred pigs (n = 32), using distended (n = 16) or nondistended (n = 16) conduits. After 3 to 90 days, the media was evaluated for the presence of smooth muscle cells (desmin stains), myofibroblast formation (transient alpha-SM actin expression), and apoptosis (TdT-mediated dUTP nick end-labeling [TUNEL])., Results: Smooth muscle loss was uniformly severe; only 5% +/- 5% (p < 0.01) and 14% +/- 9% (p < 0.01) of the medial area of distended and nondistended veins were desmin positive in comparison with 80% +/- 9% of controls. Apoptosis appeared to contribute to medial smooth muscle loss (5.7% +/- 4.3% in vein grafts versus 0.0% +/- 0.0% of TUNEL-positive cells in controls; p = 0.05). There was a time dependent increase in medial myofibroblast formation (p < 0.05)., Conclusions: Severe medial smooth muscle loss occurs in vein grafts, even when prepared without distension. Apoptosis contributes to the early disappearance of smooth muscle cells. Adjunctive measures, in addition to ideal surgical techniques, should be developed to prevent medial muscle loss.

To characterize long-term vascular remodeling associated with neointimal formation in vivo, we established a model of balloon injury in normal chow fed rabbits. The iliac artery was injured by denudation using a 2F embolectomy catheter. Injured vessels were removed after perfusion fixation (90 mm Hg) in situ at 2, 4, 6, and 12 weeks post-injury; control vessels were obtained from 2- and 12-week age-matched, uninjured animals. Intimal growth was observed in all animals post-injury. Intimal area averaged 0.13 +/- 0.02 mm2 2 weeks post-injury and continued to increase at 4 and 6 weeks post-injury; +38% and +77% relative to the 2-week time point, respectively. Medical areas were similar among the 2-, 4-, and 6-week injury groups and the 2- and 12-week control groups. From 6 to 12 weeks post-injury, both intimal and medial areas decreased significantly (30% and 34%, respectively); while lumen area increased 53% from 4 to 12 weeks and overall vessel size (area enclosed by the external elastic lamina) remained the same. These data demonstrate that intimal and medial thinning contribute to long term maintenance of lumen area in response to neointimal formation.

Background and Objective: Restenosis after balloon angioplasty is the summated effect of intimal hyperplasia and arterial shrinkage, both caused by hyperproliferation. In the present study, the potential of a photochemotherapeutic modality (Psoralen + UVA: PUVA) for the prevention of angioplasty induced proliferation was explored., Study Design/materials and Methods: In rabbit iliac arteries, balloon dilation followed by PUVA-therapy (H = 1 J/cm2) was performed (n = 15). Contralateral arteries served as control. After 2 and 28 days of survival, the contribution of intimal hyperplasia and remodeling to lumen loss was determined by means of angiography and histological analysis., Results: After 2 days, large parts of the media had become acellular, while proliferation was occurring predominantly in the adventitia in both groups. After 28 days, late loss, arterial shrinkage, but not intimal hyperplasia were larger in the PUVA group (P < 0.05)., Conclusion: PUVA-therapy did not prevent intimal hyperplasia following balloon dilation but enhanced luminal narrowing by augmented constrictive remodeling.

The study evaluates whether the Watanabe heritable hyperlipidemic (WHHL) rabbit is an adequate model to study mechanisms that underlie differences in tissue response after postangioplasty injury. Postangioplasty studies of human coronary arteries have revealed that healing and restenotic processes differ depending on whether the laceration is limited to the atherosclerotic plaque or whether injury extends into the media. Forty-five homozygous WHHL rabbits underwent percutaneous transluminal angioplasty of the left subclavian artery. The inflated arterial segment was studied histologically at 3, 7, 14, 28, and 56 days, using conventional and immunohistochemical techniques to identify macrophages, smooth muscle cell (SMC) phenotypes, and cell proliferation. Electron microscopy was done to study reendothelialization. There were marked differences in response between those segments with medial injury and those with injury limited to the atherosclerotic plaque tissues. The latter category shows a distinct retardation in redifferentiation of SMCs, confirming previous observations in human coronary arteries. In these segments, moreover, cell proliferation occurred mainly in macrophages and spindle cells. Medial injury showed a more florid fibrocellular response, as in human coronary arteries, with cell proliferation initially confined to areas with dedifferentiated SMCs in the preexistent media and, once neointimal tissue was formed, among spindle cells also. The similarities with the repair processes encountered in postangioplasty human coronary arteries suggest that the WHHL rabbit is an adequate model to study differences in the response related to different types of angioplasty injury.

Background: Ionizing radiation has been shown to reduce vascular lesion formation after balloon overstretch injury of pig coronary arteries. The present series of experiments examines the mechanism by which this occurs., Methods and Results: Balloon injury was performed on porcine coronary arteries, followed immediately by ionizing radiation using either a source train of 90Sr/Y or 192Ir seeds designed to deliver 14 or 28 Gy at a depth of 2 mm from the source. The animals were killed 3, 7, or 14 days after injury. Bromodeoxyuridine was administered 24 hours before euthanasia to label proliferating cells. Cell proliferation was significantly reduced on day 3 in the adventitia and media of the irradiated vessels compared with controls. Two weeks after injury, there were fewer alpha-actin-positive myofibroblasts in the adventitia of the irradiated vessels than in nonirradiated controls, and morphometric analysis indicated that the vessel perimeter of the irradiated vessels was significantly larger than in controls. Together, these results suggest a positive effect of intravascular irradiation on vascular remodeling. Apoptosis was estimated by terminal transferase dUTP-biotin nick-end labeling (TUNEL) 3 and 7 days after injury. TUNEL-labeled cells were found primarily in the adventitia at the medial tear, but no differences were detected between irradiated and control vessels., Conclusions: These studies suggest that intracoronary radiation primarily inhibits the first wave of cell proliferation in the vessel wall and demonstrates a favorable effect on late remodeling by preventing adventitial fibrosis at the injury site.

Objectives: We describe a new angioplasty device (Infiltrator Angioplasty Balloon Catheter; IABC) with intramural drug delivery capability. The conventional balloon part of the device, when inflated, dilates the vessel or has three rows of longitudinally mounted infiltrator nipples to penetrate the tunica media. Through an independent infiltrator port and nipples, drugs can be infiltrated directly into the vessel wall., Methods: The device was tested in 117 normal coronary arteries of 58 farm pigs., Results: (1) The infiltration procedure does not damage the vessel angiographically or histologically. At the infiltration site, the endothelial layer and the internal elastic lamina has a controlled interruption, and the infiltrated fluid is distributed among the medial layers, causing a mild focal edema and medial thickening (1.8 times on average). (2) Rhodamine tracer is circularly and evenly distributed through the whole width of the vessel wall within 10 min after infiltration. (3) Two weeks after the infiltration procedure, the medial layer reveals mild local thickening and remodelling without luminal narrowing. (4) Of the intramurally infiltrated Tcm99-labeled surfurcolloid, 83.8% is detectable at 5 min after the delivery procedure by gamma camera. (5) The IABC, if oversized, is able to achieve angiographic dilatation in normal pig coronary arteries, causing histologic damage similar to or less than that induced by conventional balloon dilatation., Conclusions: The IABC can deliver fluid-phase substances directly into the vessel wall with microliter accuracy and with 90% efficiency without significant acute and subacute damage to the vessel wall. It is also suitable for combined dilatation and local drug delivery.

Objectives: Sufficient intramural drug concentrations with the use of porous balloon catheters can be achieved with additional vascular trauma only. However, effective delivery of a potent drug even in deeper layers of the vessel wall might outweigh these traumatic side effects. Given the porous balloon catheter, the parameters of injection pressure and applied fluid volume will influence the interventional result., Methods: We tested a 2.5-mm porous balloon (35 75-micron pores) in the right carotid artery of New Zealand rabbits and used injection pressures of 1, 2, and 5 atm and fluid volumes of 2 and 4 ml of low-molecular-weight heparin solution in combination with the different parameters (n = 5 animals/group). In 50 rabbits, an intimal fibromuscular plaque was induced by using the electrostimulation model. Balloon dilatation and then application of the porous balloon was performed in 30 animals, 10 animals were only electrostimulated, and 10 animals served as a control group with balloon dilatation only. The vessels were excised 7 d after intervention, stained, and analyzed histomorpologically. Anti-Xa assays revealed the extent of systemically escaped drug, and serial cuts allowed for exact determination of vessel wall injuries., Results: Effective local drug delivery could not be achieved with an injection pressure of less than 2 atm. Specific pressure-driven effects such as jet injuries could be identified. When the pressure was high enough for disruptive drug delivery (> or = 2 atm), fluid volumes of 4 ml led to loose elastic membranes and local thickening within the media., Conclusions: Sufficient intramural drug distribution using porous balloon catheters can be achieved with low injection pressures. Different fluid volumes strongly determine the extent of additional vascular injury.

This study was designed to evaluate the feasibility of applying locally delivered polylactic acid microspheres for drug delivery to the arterial wall. To study drug persistence, rhodamine-loaded microspheres were infused into one carotid artery of 14 rabbits and plain rhodamine solution into the other by using a porous balloon. To study tissue response, plain microspheres and dexamethasone-loaded microspheres were infused into the carotid arteries of another group of rabbits. To study the antiproliferative effects of locally delivered drug, 20 rabbits were subjected to overstretch balloon injury to both carotid arteries and divided into 4 groups: injury alone, plain microspheres, dexamethasone-loaded microspheres, and microspheres containing colchicine and dexamethasone. Fluorescent microspheres persisted in the vessel wall for 4 wk, whereas rhodamine without microspheres disappeared at 72 h. Histopathologic studies in arteries infused with unloaded microspheres showed inflammatory cell infiltrate with polymorphonuclear cells at 1 wk and macrophages and giant cells at 4 wk. Arteries infused with dexamethasone-loaded microspheres did not show any inflammatory cell infiltrate. Local delivery of dexamethasone or dexamethasone plus colchicine did not result in significant change in the intima-to-media ratio or in residual lumen following balloon injury. Polylactic acid microspheres may be used for prolonged delivery of drugs or other bioactive agents locally to the arterial wall. They induce an inflammatory reaction that is suppressable by dexamethasone in the microspheres. Dexamethasone or dexamethasone and colchicine delivered via this system, however, failed to reduce the degree of intimal hyperplasia after overstretch balloon injury to the rabbit carotid arteries.

Drug delivery by iontophoresis involves the application of an electric field to move selectively charged drug molecules across biological membranes. The purpose of this study was to assess the efficacy of intravascular iontophoresis in the local delivery of heparin to balloon angioplasty sites by using a recently designed iontophoretic catheter. In vivo heparin iontophoresis was assessed in 33 rats and 21 pigs in four protocols designed to measure the technical determinants of intramural drug deposition, the pharmacokinetics and localization of coronary delivery, and the effect of this technique on platelet deposition following balloon injury. First, iontophoresis of 3H-heparin into the aorta of 33 rats was performed to determine the effects of iontophoretic current, iontophoretic membrane balloon initiation pressure, iontophoresis time, and heparin concentration on intramural drug deposition. Second, iontophoresis of 3H-heparin was performed in 16 porcine coronary arteries to quantitate immediate drug delivery and subsequent wash-out over 24 h. Third, iontophoresis of fluorescent heparin was performed in 8 porcine coronary arteries to define intramural localization of locally delivered drug. Fourth, 111In-labeled platelet deposition was measured 1 h following balloon angioplasty and local iontophoretic heparin delivery in 16 porcine carotid and iliac vessels. Contralateral control vessels that were dilated with the same size balloon and treated with iontophoresis of saline served as controls. Rat aortic studies demonstrated that iontophoresis resulted in 13 times more intramural heparin deposition than passive delivery (passive: 0.3 +/- 0.4 microgram, iontophoresis: 4.6 +/- 1.6 micrograms, P < 0.0004). Iontophoretic membrane balloon inflation pressure had no significant effect on intramural drug deposition, but longer iontophoresis times and higher heparin concentrations resulted in higher levels of intramural heparin (P < 0.05). Porcine coronary studies demonstrated successful intramural deposition of heparin in all arteries without adverse electrical or hemodynamic sequelae, with persistence of the drug for at least 24 h. Localization studies demonstrated immediate deposition of fluorescent heparin in the intima and internal elastic lamina, with subsequent rapid diffusion of the drug into the media. Porcine platelet studies demonstrated that heparin iontophoresis decreased platelet deposition following balloon injury by approximately 66% compared with saline-treated control vessels (heparin-treated: 1.46 +/- 2.51 x 10(8), control: 4.27 +/- 7.02 x 10(8), P = 0.001). This study has demonstrated that local intramural heparin delivery is feasible with an intravascular iontophoretic catheter. Following intracoronary heparin iontophoresis in the porcine model, intramural drug is detected for at least 24 h. Local delivery of heparin with this technique significantly decreases early platelet deposition following balloon injury in peripheral porcine arteries.

The Channel balloon is a new local drug-delivery catheter that has the dual capability of high-pressure lesion dilation and low-pressure drug infusion. The purpose of this study was to assess the safety and efficacy of this device in the local delivery of urokinase in the porcine model. Three in vivo protocols were performed in 57 anesthetized swine to assess the safety of Channel balloon use in the coronary vasculature, the pharmacokinetics of local urokinase delivery, and the ability of the catheter to lyse intraluminal thrombus. First, safety studies were performed in 18 coronary vessels in 13 pigs to compare angiographic and histologic changes following use of the Channel balloon with conventional balloon angioplasty. Second, intramural deposition of 123I-labeled urokinase was measured in 24 coronary arteries in 20 pigs to assess the efficiency and technical determinants of urokinase delivery and the time course of intramural drug retention. Finally, an in vivo thrombus model was used in 24 pigs to compare the thrombolytic capacity of local urokinase delivery with the Channel balloon in comparison with conventional urokinase infusion techniques. All balloon inflations and drug infusions with the Channel balloon were well tolerated in all animals without adverse angiographic, hemodynamic, or electrical sequelae. Comparative histologic studies with the Channel balloon demonstrated no additional vessel trauma beyond that seen with conventional balloon angioplasty. Between 0.09 and 0.35% of infused urokinase was intramurally deposited, with intracoronary persistence for at least 5 h. Drug infusion pressure did not significantly affect drug deposition, although larger amounts of urokinase were deposited with larger balloon:artery ratios and higher urokinase concentrations. In comparison to conventional systemic and guiding catheter infusions, local delivery of urokinase with the Channel balloon resulted in higher levels of clot dissolution. These studies have demonstrated safe intracoronary use of the Channel balloon in the porcine model. Local infusion of urokinase with this device results in significant intramural drug deposition that persists for at least 5 h. In comparison with conventional thrombolytic techniques, local urokinase delivery with the Channel balloon may result in enhanced intravascular thrombolysis.

When delivered locally to the arterial wall by passive fluid transfer systems such as perforated balloons, water-soluble compounds in aqueous solution are not readily taken up by tissue, show low levels of cellular localization, and are quickly lost by wash-out. One approach to improve delivery is addition of an "active" component to the catheter system to change the nature of the drug-to-tissue interaction. Using an iontophoretic balloon catheter to deliver antisense oligonucleotide (ODN) to pig coronary arteries after balloon angioplasty, we determined the quantity and localization of ODN in the tissue. By radiolabeling, 7.3 +/- 2.4 micrograms ODN was present at 30 min, 1.5 +/- 0.6 at 2 h, 0.52 +/- 0.35 at 24 h, and 0.26 +/- 0.11 at 7 d. By fluorescent labeling, circumferential medial uptake and adventitial delivery at the site of medial injury was observed, with primarily cellular localization. The iontophoretic catheter thus appears to be a useful device for ODN delivery to arterial tissue.

The objective was to assess the arterial wall response to temporary stenting with a removable nitinol stent in comparison with permanent stenting and balloon injury at 28 days in the rabbit carotid artery. Restenosis remains an important limiting factor after the implantation of permanent metallic stents and balloon angioplasty. We have developed a temporary nitinol stent that uses a bolus injection of warmed saline to collapse the stent for percutaneous removal. Vascular changes related to the thermal saline bolus injection required to remove a nitinol implanted stent were assessed in 12 rabbit carotid arteries at 7 and 28 days postinjection. Nitinol stents, inflated to 3.0 mm diameter, were implanted for 3 days (n = 6) and histology and quantitative histomorphometry examined at 28 days. Results were compared with permanently implanted stents (n = 5) and balloon injury (n = 9). Dual bolus injection of 10 ml at 70 degrees C created an acute necrotizing injury and chronic neointimal proliferation, whereas injections of 5 ml at 63 degrees C were minimally injurious. Temporary stenting resulted in the least neointimal proliferation measured by the intima to media ratio (0.22 +/- 0.10 vs. 1.59 +/- 0.31 for permanent stenting and; 0.49 +/- 0.14 for balloon injury; P < 0.001). Temporary stenting maintained a significantly larger lumen than balloon (1.53 +/- 0.72 mm2 vs. 0.64 +/- 0.14 mm2; P < 0.001), which could not be explained by absolute changes in intimal cross sectional area (0.14 +/- 0.07 mm2 vs. 0.21 +/- 0.06 mm2 respectively; P = 0.33). Temporary stenting resulted in a relatively larger vessel area within the external elastic lamina than with balloon (2.28 +/- 1.06 mm2 vs. 1.30 +/- 0.18 mm2; P = 0.007). The thermal stent recovery process can create necrotizing vascular injury and neointimal proliferation at higher temperatures and injectate volumes. Stent removal after 3 days using 63 degrees C saline bolus injection results in less neointimal proliferation than with permanent stents or balloon injury. In comparison to balloon injury, temporary stenting also may have a long-lasting beneficial effect on vessel recoil and remodeling, resulting in larger lumen size after stent removal.

We studied the expression of each component of the renin-angiotensin system (renin, angiotensin I-converting enzyme, angiotensinogen, and angiotensin II type I receptor) in balloon-injured rat carotid artery. We assessed the expression levels of the respective mRNAs by competitive polymerase chain reaction. Renin mRNA concentration was markedly increased 24 hours after balloon injury and remained higher than that in the control at 7 days after balloon injury. Angiotensin-converting enzyme mRNA concentration was decreased 24 hours after balloon injury and was increased at 14 days after balloon injury. No significant change in angiotensinogen mRNA concentration was observed throughout the study period. Angiotensin type I receptor mRNA concentration was increased beginning 3 days after balloon injury and remained higher than that in the control at 14 days after balloon injury. Immunohistochemical analysis showed that renin was transiently expressed in medial smooth muscle cells after balloon injury. Administration of quinapril markedly reduced neointimal formation and was accompanied by an attenuation of the increase in the concentrations of angiotensin type I receptor and angiotensin-converting enzyme mRNAs. The upregulation of renin mRNA in balloon-injured rat carotid artery preceded and may play a role in neointimal formation.