The dynamic nature of coronary artery lesion morphology assessed by serial virtual histology intravascular ultrasound tissue characterization

OBJECTIVES

We used virtual histology intravascular ultrasound (VH-IVUS) to investigate the natural history of coronary artery lesion morphology.

BACKGROUND

Plaque stability is related to its histological composition.

METHODS

We performed serial (baseline and 12-month follow-up) VH-IVUS studies and examined 216 nonculprit lesions (plaque burden >or=40%) in 99 patients. Lesions were classified into pathological intimal thickening (PIT), VH-IVUS-derived thin-capped fibroatheroma (VH-TCFA), thick-capped fibroatheroma (ThCFA), fibrotic plaque, and fibrocalcific plaque.

RESULTS

At baseline, 20 lesions were VH-TCFAs; during follow-up, 15 (75%) VH-TCFAs "healed," 13 became ThCFAs, 2 became fibrotic plaque, and 5 (25%) VH-TCFAs remained unchanged. Compared with VH-TCFAs that healed, VH-TCFAs that remained VH-TCFAs located more proximally (values are median [interquartile range]) (16 mm [15 to 18 mm] vs. 31 mm [22 to 47 mm], p = 0.013) and had larger lumen (9.1 mm(2) [8.2 to 10.7 mm(2)] vs. 6.9 mm(2) [6.0 to 8.2 mm(2)], p = 0.021), vessel (18.7 mm(2) [17.3 to 28.6 mm(2)] vs. 15.5 mm(2) [13.3 to 16.6 mm(2)]; p = 0.010), and plaque (9.7 mm(2) [9.6 to 15.7 mm(2)] vs. 8.4 mm(2) [7 to 9.7 mm(2)], p = 0.027) areas; however, baseline VH-IVUS plaque composition did not differ between VH-TCFAs that healed and VH-TCFAs that remained VH-TCFAs. Conversely, 12 new VH-TCFAs developed; 6 late-developing VH-TCFAs were PITs, and 6 were ThCFAs at baseline. In addition, plaque area at minimum lumen sites increased significantly in PITs (7.8 mm(2) [6.2 to 10.0 mm(2)] to 9.0 mm(2) [6.5 to 12.0 mm(2)], p < 0.001), VH-TCFAs (8.6 mm(2) [7.3 to 9.9 mm(2)] to 9.5 mm(2) [7.8 to 10.8 mm(2)], p = 0.024), and ThCFAs (8.6 mm(2) [6.8 to 10.2 mm(2)] to 8.8 mm(2) [7.1 to 11.4 mm(2)], p < 0.001) with a corresponding decrease lumen areas, but not in fibrous or fibrocalcific plaque.

CONCLUSIONS

Most VH-TCFAs healed during 12-month follow-up, whereas new VH-TCFAs also developed. PITs, VH-TCFAs, and ThCFAs showed significant plaque progression compared with fibrous and fibrocalcific plaque.

MIR-23A microRNA cluster inhibits B-cell development

OBJECTIVE

The transcription factor PU.1 (encoded by Sfpi1) promotes myeloid differentiation, but it is unclear what downstream genes are involved. Micro RNAs (miRNAs) are a class of small RNAs that regulate many cellular pathways, including proliferation, survival, and differentiation. The objective of this study was to identify miRNAs downstream of PU.1 that regulate hematopoietic development.

MATERIALS AND METHODS

miRNAs that change expression in a PU.1-inducible cell line were identified with microarrays. The promoter for an miRNA cluster upregulated by PU.1 induction was analyzed for PU.1 binding by electrophoretic mobility shift and chromatin immunoprecipitation assays. Retroviral transduction of hematopoietic progenitors was performed to evaluate the effect of miRNA expression on hematopoietic development in vitro and in vivo.

RESULTS

We identified an miRNA cluster whose pri-transcript is regulated by PU.1. The pri-miRNA encodes three mature miRNAs: miR-23a, miR-27a, and miR-24-2. Each miRNA is more abundant in myeloid cells compared to lymphoid cells. When hematopoietic progenitors expressing the 23a cluster miRNAs were cultured in B-cell-promoting conditions, we observed a dramatic decrease in B lymphopoiesis and an increase in myelopoiesis compared to control cultures. In vivo, hematopoietic progenitors expressing the miR-23a cluster generate reduced numbers of B cells compared to control cells.

CONCLUSIONS

The miR-23a cluster is a downstream target of PU.1 involved in antagonizing lymphoid cell fate acquisition. Although miRNAs have been identified downstream of PU.1 in mediating development of monocytes and granulocytes, the 23a cluster is the first downstream miRNA target implicated in regulating development of myeloid vs lymphoid cells.

A randomized comparison of a novel bioabsorbable vascular closure device versus manual compression in the achievement of hemostasis after percutaneous femoral procedures: the ECLIPSE (Ensure's Vascular Closure Device Speeds Hemostasis Trial)

OBJECTIVES

This trial compared the performance of a novel bioabsorbable vascular closure device (VCD) versus manual compression (MC) for access site hemostasis in patients undergoing percutaneous trans-femoral coronary or peripheral procedures.

BACKGROUND

From a patient's perspective, access site management after percutaneous procedures remains challenging.

METHODS

Patients enrolled in this multicenter, nonblinded trial underwent 6-F diagnostic or interventional procedures were randomly assigned 2:1 to VCD versus MC. The primary efficacy end points were time to hemostasis (TTH) and time to ambulation (TTA), and the primary safety end points were periprocedural and 30-day incidence of arterial access-related complications.

RESULTS

The trial assigned 401 patients (mean age 62.7 +/- 10.9 years, 66.1% men) to VCD (n = 267) versus MC (n = 134) after 87 "roll-in" patients treated at 17 participating institutions. The baseline characteristics of the groups were similar. Procedural success was 91.8% in the VCD versus 91.0% in the MC group (p = NS). Mean TTH was 4.4 +/- 11.6 min in the VCD versus 20.1 +/- 22.5 min in the MC group (95% confidence interval: 19.0 to 12.3; p < 0.0001). Likewise, TTA was significantly shorter in the VCD (2.5 +/- 5.0 h) than in the MC (6.2 +/- 13.3 h) group (95% confidence interval: 5.5 to 1.9; p = 0.0028). No patient died or suffered a major access-site-related adverse event. Minor adverse events were few among all study groups.

CONCLUSIONS

After 6-F percutaneous invasive procedures, TTH and TTA were both significantly shorter in patients assigned to VCD than in patients managed with MC. The 30-day rates of access-site-related complications were remarkably low in all groups. (Safety and Effectiveness Study of the Ensure Medical Vascular Closure Device; NCT00345631).

The Tricuspid Valve

Cardiovascular specialists have entered an era of renewed interest and enthusiasm surrounding the diagnosis and treatment of valvular heart disease, driven in part by emerging percutaneous therapies for the treatment of aortic, pulmonic, and mitral valve disease. Despite this wave of investigation, little or no attention has been given to the treatment of tricuspid valve disease. Tricuspid regurgitation (TR) occurs mainly from tricuspid annular dilation, which can result from left-sided heart failure from myocardial or valvular causes, right ventricular volume and pressure overload, or dilation of cardiac chambers. If untreated at the time of surgical mitral valve repair, significant residual TR negatively impacts perioperative outcomes, functional class, and survival. TR does not reliably resolve after successful mitral valve surgery. If present at the time of mitral valve surgery, TR can usually be effectively addressed with ring annuloplasty. Because reoperations for recurrent TR carry high mortality rates, few patients are offered reoperation for redo tricuspid repair or replacement. As transcatheter therapies for mitral regurgitation arise, parallel percutaneous approaches for TR may be necessary. In this article, we review the anatomy, pathophysiology, and value of mechanical correction of TR, including potential transcatheter therapies for TR.

Long-term safety and durability of percutaneous septal sinus shortening (The PS(3) System) in an ovine model

OBJECTIVES

Chronic implants of the PS(3) system were conducted in an ovine model to assess durability and safety at up to 1 year follow-up.

BACKGROUND

The long-term durability and safety of emerging percutaneous devices for functional mitral regurgitation remain largely unknown.

METHODS

The PS(3) system (consisting of interatrial septal and great cardiac vein devices connected by an adjustable suture bridge) was placed in eight healthy adult sheep. The mitral annular septal-lateral dimension in systole (SLS) was acutely reduced by 15-20%. Animals were sacrificed at up to 12 months postimplant and characterized by intracardiac echocardiography, cardiac computed tomography (CT), and histopathology. In vivo forces exerted on the PS(3) bridge were measured by means of a novel load cell catheter.

RESULTS

At 3, 6, and 12 months after implantation, intracardiac echocardiographic and CT showed the PS(3) systems to be intact without erosion and with overall sustained reductions in the SLS. Histopathologic assessment revealed each component correctly deployed in its respective target site without evidence of erosion, thrombus, or device fracture. The SLS was 26.5 +/- 1.7 mm preimplant, 22.0 +/- 1.4 mm post-PS(3) (17.0% reduction), and 22.0 +/- 2.1 mm at latest follow-up. Mean forces exerted on the bridge in vivo ranged from 1.16 N to 1.87 N.

CONCLUSIONS

The PS(3) System demonstrated excellent biocompatibility without evidence of erosion, thrombosis, or perforation at up to one-year follow-up in this chronic healthy ovine model. Forces exerted in the PS(3) system were relatively modest and should contribute to the durability of the device.

Effect of percutaneous mitral repair with the MitraClip device on mitral valve area and gradient

AIMS

Percutaneous repair of mitral regurgitation (MR) by leaflet apposition using a clip deployed via transseptal catheterisation is undergoing evaluation.

METHODS AND RESULTS

In order to detect the potential for clinically significant left ventricular inflow obstruction after percutaneous repair, we measured mitral valve area (MVA) and mean transmitral gradient (MVG) echocardiographically in 96 patients implanted with a clip followed for up to 24 months. By planimetry, the mean MVA decreased from 6.0 +/- 1.3 cm2 to 3.6 +/- 1.2 cm2 (p < 0.05) (range 1.9 to 7.6 cm2) after clip placement, and remained unchanged after 24 months of follow-up (3.5 +/- 0.8 cm2). The mean MVG increased after clip placement from 1.7 +/- 0.9 mmHg to 4.1 +/- 2.2 mmHg (p < 0.05), and did not increase further to 24 months (3.8 +/- 1.9 mmHg). There were no differences in MVA or MVG between patients who received 1-clip (69%) and those receiving 2-clips (31%). Patients with functional MR (23%) had a slightly smaller MVA, both at baseline and after clip placement, but did not differ from degenerative MR patients at later follow-up. After 2 years of follow-up, no patient required surgery for LV inflow obstruction.

CONCLUSIONS

Mitral repair with the MitraClip device for MR decreases MVA without significant mitral obstruction. After 2 years of follow-up, no patient required surgery for LV inflow obstruction, and these results were not influenced by the use of more than 1 clip or the aetiology of MR.

Use of stent grafts and coils in vessel rupture and perforation

Vessel rupture and perforation are important complications of percutaneous treatment of coronary and peripheral arterial disease. These complications can result in abrupt vessel closure, distal organ injury, bleeding into the surrounding tissue, and death. Prompt management of such complications is therefore critically important. This paper reviews the management of vessel rupture and perforation, including the use of different types of covered stents (balloon-expandable and self-expanding), as well as the various types of embolization coils. Particular focus will be placed on percutaneous coronary artery and peripheral arterial interventions.

COURAGE: in the eye of the beholder

The following comment provides another perspective on the COURAGE Trial. A prior Editorial on this subject was by Franklin (Franklin BA. Lessons learned from the COURAGE Trial: generalizability, limitations, and implications. Prev Cardiol. 2007;10(3):117-120.).-Ezra A. Amsterdam, MD, Editor in Chief.

Dual mechanism platypnea-orthodeoxia syndrome from severe right coronary artery stenosis and a patent foramen ovale

Platypnea-orthodeoxia is a rare clinical syndrome characterized by hypoxemia induced during upright posture. Multiple mechanisms have been proposed to explain this clinical entity, usually involving posture-provoked intracardiac or transpulmonary shunting. In many cases, however, a single etiology may not be evident, and multiple factors are likely contributory. We herein describe an unusual and novel case of platypnea-orthodeoxia caused by the physiologic interaction between a severe proximal right coronary artery stenosis and a large patent foramen ovale. Percutaneous stenting of the right coronary artery and transcatheter closure of the patent foramen ovale during the same setting resulted in complete resolution of the patient's symptoms.

Safety and feasibility of acute percutaneous septal sinus shortening: First-in-human experience

BACKGROUND

Multiple percutaneous therapies for the treatment of functional and ischemic mitral regurgitation (FMR/IMR) are under development. We previously reported a novel percutaneous technique, the percutaneous septal sinus shortening [PS(3)] System which was effective in ameliorating FMR in an animal model. We herein report results from the first-in-human safety and feasibility pilot study involving the PS(3) System.

METHODS AND RESULTS

The primary objective of this first-in-human study was to evaluate the safety and feasibility of acute percutaneous septal-lateral shortening by using the PS(3) System in patients immediately prior to clinically-indicated surgical mitral valve repair. Two patients were enrolled. Patient One had severe aortic insufficiency with moderate functional mitral regurgitation. The PS(3) System reduced the MR grade from 2+ to 1+ with a decrease in the mean septal-lateral systolic (SLS) dimension from 38 to 27 mm (29% reduction). Patient Two had severe ischemic mitral regurgitation in the setting of severe multi-vessel disease and prior infero-posterior infarct. MR grade was reduced from 3+ to 1+ with a decrease in the mean SLS dimension from 36 to 25mm (31% reduction). There were no procedural complications and both patients proceeded to pre-planned cardiac surgery, where the devices were explanted under direct visualization.

CONCLUSIONS

The PS(3) System has been safely translated from the preclinical setting to first-in-human implantation. Both patients studied experienced a reduction in MR after device implantation, with significant SLS shortening. Further clinical trials will be needed to assess long-term efficacy and durability.

Diagnosis and Management of Subclavian Artery Stenosis Prior to Coronary Artery Bypass Grafting in the Current Era

There are several approaches to managing subclavian artery stenosis (SAS) prior to coronary artery bypass grafting (CABG) with an intended internal thoracic artery (ITA) graft to the left anterior descending (LAD) artery. We herein review the incidence of and various diagnostic modalities for detecting SAS. Published relevant clinical studies from the interventional cardiovascular and cardiac surgical literature are summarized. Particular emphasis is placed on the efficacy of various approaches to the patient diagnosed with SAS prior to CABG. Stenting the subclavian artery prior to bypass surgery and using an in situ ITA is compared to using the ITA as a "free" graft. The incidence of restenosis after subclavian artery angioplasty or stenting is not trivial and has been reported to occur at a rate of 6% to 21%; however, the average rate of restenosis with stenting appears to be in the mid-teens. Subacute subclavian stent thrombosis or occlusion is exceptionally rare, suggesting that a percutaneous approach to SAS is reasonable prior to CABG. For patients requiring emergent revascularization, placement of a free ITA graft to the LAD appears to be a safe and durable treatment as patency rates are comparable to that of an in situ LITA to the LAD. In summary, although no randomized clinical trials address the optimal management of SAS prior to CABG, both percutaneous and surgical options appear to be safe and reasonably durable.

Assessment of FFR-negative intermediate coronary artery stenoses by spectral analysis of the radiofrequency intravascular ultrasound signal

BACKGROUND

Assessing the clinical importance of angiographically intermediate coronary artery stenoses at the time of cardiac catheterization remains a challenge. Spectral analysis of radiofrequency ultrasound backscatter signals, or virtual histology (VH), allows in vivo assessment of plaque composition. This study characterizes the VH composition of fractional flow reserve (FFR)-negative intermediate stenoses and adjacent vessel segments.

METHODS

Intermediate coronary artery stenoses (> 40% and < 70% diameter stenosis) were assessed by pressure wire. If the FFR was > or = 0.75, percutaneous coronary intervention was deferred and VH was performed on the lesion and adjacent segments using a commercially available system. The primary clinical endpoint was any adverse cardiac event.

RESULTS

Thirty-seven intermediate stenoses in 30 patients were studied. The reference vessel size was 3.02 +/- 0.71 mm, the QCA diameter stenosis was 52 +/- 6% and the FFR was 0.89 +/- 0.07. The target stenoses were characterized by VH as: thin-cap fibroatheroma (VH-TCFA; n = 22); fibrous cap atheroma (n = 5), fibrocalcific lesion (n = 7) and pathological intimal thickening (n = 3). The relative contribution of each stenosis plaque component was conserved across adjacent segments ("signature" plaque). Three patients, all with VH-TCFAs at index, had events in the clinical follow-up period of 12 +/- 2 months, but only 1 of these patients had an event related to the index stenosis.

CONCLUSIONS

FFR-negative intermediate stenoses have heterogeneous plaque by VH, but are enriched in VH-TCFAs. Relative plaque composition is conserved along adjacent vessel segments. Although the specificity of VH-TCFA for index stenosis-related events appears low, larger trials are needed to assess the prognostic value of VH in this lesion subset.

Percutaneous Septal Sinus Shortening

Background— The septal-to-lateral (SL) mitral annular diameter is increased in functional mitral regurgitation (MR). We describe a novel percutaneous technique (the percutaneous septal sinus shortening system) that ameliorates functional MR in an ovine model.

Methods and Results— Sheep underwent rapid right ventricular pacing to obtain moderate to severe functional MR with SL enlargement. The percutaneous septal sinus shortening system was placed via standard interventional techniques consisting of a bridge (suture) element between interatrial septal wall and great cardiac vein anchors. Through progressive tensioning of the bridge element, direct SL shortening was achieved. Sheep underwent short-term (n=19) and long-term (n=4) evaluation after device implantation. In short-term studies, SL diameter decreased an average of 24% (32.5±3.5 to 24.6±2.4 mm; P <0.001), and MR grade significantly improved (2.1±0.6 to 0.4±0.4; P <0.001). Despite continued rapid pacing, chronic device implantation resulted in durable SL shortening (30.4±1.9 mm before implantation to 25.3±0.8 mm at 30 days; P =0.01) and MR reduction (1.8±0.5 before implantation to 0.2±0.1 at 30 days; P =0.01). Increased cardiac output, decreased wedge pressure, and decreased brain natriuretic peptide levels were observed in animals undergoing long-term device implantation.

Conclusions— The percutaneous septal sinus shortening system is effective in ameliorating functional MR in an ovine tachycardia model. The procedure, which uses standard catheter techniques, can be deployed largely under fluoroscopic guidance. The unique bridge element appears durable and allows direct and precise SL shortening to a diameter optimal for MR reduction.

Coronary artery dissection and perforation complicating percutaneous coronary intervention

Percutaneous coronary intervention (PCI) is widely utilized in the treatment of symptomatic coronary artery disease. Despite its numerous benefits, serious and potentially life-threatening complications of PCI can occur, including iatrogenic coronary artery dissection and perforation. The incidence of these complications has been augmented by the development of coronary interventional devices intended to remove or ablate tissue. We herein review the classification, incidence, pathogenesis, clinical sequelae and management of coronary artery dissection and perforation in the current era. Specifically, the current angiographic classifications of coronary artery dissections and perforations are reviewed. The findings of several recent, large registries of PCI-related coronary artery perforations are summarized. The management of coronary artery dissection and perforation is discussed at length, including the application of newer modalities such as covered stents.

Clinical Utility of Rapid Prescreening Magnetic Resonance Angiography of Peripheral Vascular Disease Prior to Cardiac Catheterization

PURPOSE

The presence of peripheral vascular disease, in particular iliofemoral disease, is responsible in part for vascular complications from femoral artery cannulation. We investigated whether prescreening for vascular obstructions with magnetic resonance angiography (MRA) in high-risk patients with peripheral vascular disease (PVD) would provide useful information to angiographers seeking to improve the safety and efficiency of femoral artery access at cardiac catheterization.

METHODS

Twelve consecutive patients with known or suspected PVD underwent contrast-enhanced, aorto-iliofemoral MRA using a real-time BolusTrak technique. Contrast-to-noise ratios for each patient were calculated. The cardiac angiographer reviewed the MRA prior to catheterization and selected an access site. The patients' subsequent clinical course was evaluated, and a postprocedure questionnaire was completed by the angiographer to define the value of the prescreening MRA.

RESULTS

No significant vascular complications occurred in these patients as defined by failure of initially chosen access site, arterial dissection, limb ischemia, pseudoaneurysm formation, hemorrhage (including retroperitoneal hematoma), or need for blood transfusion or emergency vascular surgical repair. Statistical frequency analysis of the responses in the postprocedure questionnaire demonstrated that the MR data were clinically valuable in (1) influencing the initial choice of access site; (2) influencing technical alterations to the standard access; and, (3) enhancing confidence in the selection of access site.

CONCLUSIONS

MRA prescreening in patients with PVD is an effective, novel adjunct to cardiac catheterization in selected patients that improves physician confidence and influences technical choices during coronary angiography from the femoral artery approach.

Percutaneous repair of coronary artery bypass graft-related pseudoaneurysms using covered JOSTENTs

Spontaneous rupture of a saphenous vein graft with pseudoaneurysm formation is a rare occurrence after coronary artery bypass grafting. Using polytetrafluoroethylene covered JOSTENTs (Jomed Inc., Rancho Cordova, California), we report the successful percutaneous repair of a large pseudoaneurysm emanating from a 23-year-old saphenous vein graft and pseudoaneurysm at the site of a radial artery graft to the circumflex coronary artery 18 days after bypass surgery. These are, respectively, the oldest saphenous vein graft-related and earliest radial artery graft-related pseudoaneurysms to have been reported in the literature to date, and illustrate the versatility of the JOSTENT in the treatment of these conditions.

Endovascular brachytherapy for treatment of bilateral renal artery in-stent restenosis

Percutaneous transluminal angioplasty of renal artery stenosis is an attractive alternative to surgical therapy. However, even with endovascular stenting, the overall rate of restenosis is 21%. While brachytherapy for coronary in-stent restenosis has proven efficacy, its use for renal artery in-stent restenosis has not been formally evaluated. We report a case of bilateral in-stent renal artery restenosis treated with endovascular brachytherapy.

Paradoxical embolization of a fractured guidewire: successful retrieval from left atrium using a snare device

In adults, paradoxical embolization of catheters or guidewire fragments related to central venous catheterization is a rare phenomenon. Reports of successful percutaneous retrieval of foreign bodies from the left atrium is also rare. We describe the successful percutaneous retrieval of a fractured guidewire that had undergone paradoxical embolization to the left atrium in an adult patient.

Matrix metalloproteases and their inhibitors are produced by overlapping populations of activated astrocytes

Matrix metalloproteases (MMPs) and tissue inhibitors of metalloproteases (TIMPs) are involved in many cell migration phenomena and produced by many cell types, including neurons and glia. To assess their possible roles in brain injury and regeneration, we investigate their production by glial cells, after brain injury and in tissue culture, and we investigate whether they are capable of digesting known axon-inhibitory proteoglycans. To determine the action of MMPs, we incubated astrocyte conditioned medium with activated MMPs, then did western blots for several chondroitin sulphate proteoglycans. MMP-3 digested all five proteoglycans tested, whereas MMP-2 digested only two and MMP-9 none. To determine whether MMPs or TIMPs are produced by astrocytes in vitro, we tested both primary cultures and astrocyte cell lines by western blotting, and compared them with Schwann cells. All cultures produced at least some MMPs and TIMPs, with no obvious correlation with the ability of axons to grow on those cells. Both MMP-9 and TIMP-3 were regulated by various cytokines. To determine which cells produce MMPs and TIMPs after brain injury, we made lesions of adult rat cortex, and did immunohistochemistry. MMP-2 was seen to be induced in activated astrocytes through the whole thickness of the cortex but not deeper, but MMP-3 was not seen in the injured brain. TIMP-2 and TIMP-3 immunoreactivities were induced in activated astrocytes in deep cortex and the underlying white matter. In situ hybridisation confirmed induction of TIMP-2 in glia as well as neurons, but showed no expression of TIMP-4. These results show that both MMPs and TIMPs are produced by some astrocytes, but TIMP production is particularly strong, especially in deep cortex and white matter which is more inhibitory for axon regeneration. Conversely the MMPs produced may not be adequate to promote migration of cells and axons within the glial scar.