Publications

Magnetic Navigation in Percutaneous Coronary Intervention

Magnetic navigation is the use of adjustable magnetic fields to precisely direct wires and equipment for clinical applications. It is a recently developed option that is now available for interventional cardiology. Procedures are based on the production of a three‐dimensional reconstruction of the vessel lumen from standard angiographic images. Knowledge of the positions of the table and image intensifier during angiography allows calculation of the vessel coordinates in real space within the patient's chest. The applied magnetic field can be changed at any time to redirect the wire tip in order to improve navigation through complex and tortuous anatomy. The digital information of the coronary reconstruction can be used in further novel ways. Firstly, the integration of multislice computerized tomography images adds information about the path of the previous lumen of chronic total occlusions. Secondly, the computed center‐line of the reconstructed vessel can be superimposed onto the live fluoroscopy images as a three‐dimensional guide. The combination of improved navigation together with the other available system features may improve time, contrast, and material usage in a range of coronary lesions. Future potential developments include improvements in equipment and software, and potential therapeutic strategies under consideration include the use of equipment to perform remote control procedures, and the integration of the system to improve bone marrow–derived stem cell delivery.

Pulmonary α-adrenoceptors: Autoradiographic localization using [3H]prazosin

Role for platelet‐activating factor in asthma

Abstract Recent studies of the effects of platelet‐activating factor (PAF) on huan and animal airways would support a putative role for this lipid mediator in asthma. PAF can induce many aspects of the clinical and pathological features seen in asthmatic airways such as airway oedema, eosinophil accumulation in the airway wall, and bronchial hyperresponsiveness. PAF has potent activity as a chemotactic agent and as an activator of eosinophils, which are prominent cells in asthmatic airways, through the activation of specific surface receptors. The interaction between PAF and eosinophils may be crucial in the pathogenesis of bronchial hyperresponsiveness in asthma. A role for PAF in asthma can now be studied using the recently developed antagonists of the PAF receptor.

Differential Regulation of Cyclo-Oxygenase-1 and Cyclo-Oxygenase-2 Gene Expression by Lipopolysaccharide Treatment <i>in vivo</i> in the Rat

1. Prostaglandins are important regulatory mediators of cardiovascular and pulmonary functions which may become disordered in patients with sepsis. The mechanisms controlling their synthesis and release under these circumstances remain unclear. Cyclo-oxygenase (COX, prostaglandin G/H synthase) is a key enzyme in prostaglandin synthesis and has two isoforms (COX-1 and COX-2). COX-1 is constitutively expressed and is probably responsible for prostaglandin release under physiological conditions, whereas COX-2 is expressed at high levels upon induction. 2. We investigated the effect of lipopolysaccharide treatment in vivo on differential COX-1 and COX-2 mRNA expression in the rat. 3. The 2.8 kb COX-1 message was detected in all lungs and seven hearts of eight control rats. In lipopolysaccharide-treated animals, COX-1 expression was reduced by approximately 5-fold in lungs and 2-fold in hearts as quantified by densitometry. In parallel, a marked upregulation of COX-2 mRNA expression was observed. The 4.4 kb COX-2 transcript was absent or expressed at low level in control lungs and hearts, but was increased by approximately 7- and 12-fold in lipopolysaccharide-treated lungs and hearts respectively. Neither the down-regulation of COX-1 nor the upregulation of COX-2 mRNA induced by lipopolysaccharide was significantly affected by pretreatment with dexamethasone in lung and heart, although expression of inducible nitric oxide synthase, induced by lipopolysaccharide, was markedly inhibited in the same tissues. 4. The down-regulation of COX-1 and upregulation of COX-2 may contribute to the multi-organ failure seen in sepsis.

Structural Response and Design of Austenitic Stainless Steel I‐section Beam‐columns Undergoing Flexural‐Torsional Buckling

Abstract In this paper, the flexural‐torsional buckling response of austenitic stainless steel I‐section beam‐columns is investigated. Finite element simulations are performed with the aim of analysing the parameters affecting the behaviour of the studied members. The accuracy and safety of the existing design provisions of the European structural stainless steel design standard EN 1993‐1‐4 (2015) are assessed. A new method providing more accurate ultimate resistance predictions for austenitic stainless steel I‐section beam‐columns undergoing flexural‐torsional buckling is put forward. The higher accuracy, safety and reliability of the proposed design rules relative to EN 1993‐1‐4 (2015) are demonstrated and the new proposals have now been included in the revised Eurocode – prEN 1993‐1‐4 (2021).

Ex-vivo and In-vivo Validation of Novel Quantitative Videodensitometric Assessment of Mitral Regurgitation Following Surgical Mitral Valve Replacement

Objective: To investigate the accuracy and interobserver variability of Quantitative videodensitometric assessment of Mitral Regurgitation (QMR) after mitral valve replacement in a preclinical ovine model.Background: Quantitative videodensitometric aortography using the time-density principle is a well-documented technique for assessment of aortic regurgitation following transcatheter aortic valve replacement, but angiographic assessment of mitral regurgitation remains at best semi-quantitative (Sellers classification) and operator dependent.Methods: Fourteen sheep underwent surgical mitral valve replacement and were followed-up up to 1 year. A tricuspid valve with endogenous tissue restoration technology - the Xeltis valve (Xeltis BV, Eindhoven, the Netherlands) was implanted in 9 animals and the Trifecta valve (St. Jude Medical, St. Paul, MN, USA) was implanted in 5 animals. At the end of the follow-up period, the animals underwent a cardiac catheterization to measure their cardiac output and transmitral gradients immediately followed by ventriculography for QMR, then the animals were euthanatized, and the valve and peri-valvular tissue were excised. A mock-circulation (HDT-500 Hydrodynamic Test System [BDC Laboratory, US]) was used to assess the ex-vivo regurgitation fraction at a cardiac output comparable to the measurement obtained in-vivo. The CAAS A-valve 2.0.2 (Pie Medical Imaging BV, Maastricht, the Netherlands) was used for assessment of QMR. The QMR values (ex-vivo or in-vivo) as well as interobserver agreements were quantified after one, two, three, and four heart cycles.Results: The in-vivo QMR had significant correlations with the ex-vivo regurgitation fraction in all the cardiac cycles (best correlation: after 3 beats R2=0.784; p=0.002). The interobserver validation analysis showed significant agreements for all individual cardiac cycle (best agreement: after 4 beats R2=0.907; p<0.001).Conclusions: Angiographic quantification of mitral regurgitation using the CAAS-A valve prototype software is feasible, accurate, and highly reproducible in a preclinical setting. Further studies are necessary to establish the clinical value of this software.

Corticosteroids

701-1 Relationship of Coronary Lesion Length to Late Angiographic and Clinical Outcome After Successful Balloon Angioplasty

The influence of target lesion length, measured by an automated edge detection system (CAAS), on late angiographic and clinical outcome after successful coronary balloon angioplasty (SA), was investigated among 3124 patients with 3513 non-occlusive native coronary lesions. Quantitative angiography was performed before and after BA and at 6 month follow up. Visually assessed post-BA diameter stenosis&lt;50% was considered successful. Late clinical outcome was considered as occurrence of or freedom from, major adverse cardiac events (“MACE”: death, myocardial infarction, coronary artery bypass graft surgery, re-intervention), or target lesion reocclusion at follow up angiography, within 6 months of BA. In univariate analysis, longer lesions were associated with larger reference vessel diameter (p&lt;0.0001) and greater acute luminal gain (p&lt;0.01), but also greater late loss (p&lt;0.001) and greater % stenosis at follow up (p&lt;0.0001). To determine whether lesion length is an independent determinant of late loss or late luminal diameter, multiple linear regression analysis was carried out, including the influence of lesion location, vessel size, pre-procedural minimal luminal diameter and procedural luminal gain. Although lesion length was associated with larger vessel size, which is an independent determinant of less luminal loss (p&lt;0.0001), longer lesions were found to be independently associated with greater late loss and a smaller luminal diameter at follow up. Dividing the lesion population in 9 equal groups (noniles), the shortest lesions (mean 2.98±0.66 mm) had a loss of 0.25±0.49 mm and a % stenosis at follow up of 43±20% while the longest (mean 10.86±1.70 mm) had a loss of 0.37±0.55 mm and a % stenosis at follow up of 50±19% (p&lt;0.0001). Despite these angiographic findings of poorer late angiographic results, the frequency of major adverse cardiac events, total occlusion or binary restenosis (diameter stenosis≥50%) at follow up, did not vary with lesion length. Conclusion Although longer coronary lesions are independently associated with less favourable late angiographic results after successful balloon angioplasty, this does not appear to translate into poorer late clinical outcome. The long term clinical implications of angiographically quantified preinterventionallesion length remain to be determined.

Analysis of concrete-filled stainless steel tubular columns under combined fire and loading

In fire scenarios, concrete-filled stainless steel tubular (CFSST) columns undergo initial loading at ambient temperature, loading during the heating phase as the fire develops, loading during the cooling phase as the fire dies out and continual loading after the fire. CFSST columns may fail some points during this process under combined fire and loading. In this paper, the failure modes and corresponding working mechanism of CFSST columns subjected to an entire loading and fire history are investigated. Sequentially coupled thermal-stress analyses in ABAQUS are employed to establish the temperature field and structural response of the CFSST column. To improve the precision of the finite element (FE) model, the influence of moisture on the thermal conductivity and specific heat of concrete during both the heating and cooling phases is considered using subroutines. Existing fire and post-fire test data of CFSST columns are used to validate the FE models. Comparisons between predicted and test results confirm that the accuracy of the FE models is acceptable; the FE models are then extended to simulate a typical CFSST column subjected to the entire loading and fire history. The behaviour of the CFSST column is explained by analysis of the temperature distribution, load versus axial deformation curves and failure response.

TCT- 309 Influence of subtended myocardial mass on intracoronary physiology indices of stenosis severity and microcirculatory function.

No abstract is provided for this article.

Five-year outcomes in patients with multivessel coronary artery disease undergoing surgery or percutaneous intervention

The outcomes from real-life clinical studies regarding the optimal revascularization strategy in patients with multivessel coronary artery disease (MVD) are still poorly investigated. In this retrospective study we assessed 5-year outcomes: primary, secondary endpoints and quality of life of 1035 individuals with severe coronary artery disease (CAD) treated either with coronary artery bypass grafting (CABG)—356 patients or percutaneous coronary intervention (PCI)—679 patients according to the recommendation of a local Heart Team (HT). At 5 years no significant difference in overall mortality and rates of myocardial infarctions (MI) were observed between CABG and PCI cohorts (11.0% vs. 13.4% for PCI, P = 0.27 and 9.6% vs. 12.8% for PCI, P = 0.12, respectively). The incidence of major adverse cardiac and cerebrovascular events (MACCE), mainly driven by increased rates of repeat revascularization (RR) were higher in PCI-cohort than in CABG-group (56.1% vs. 40.4%, P &lt; 0.01 and 26.8% vs. 12.6%, P &lt; 0.01, respectively), while CABG-patients experienced stroke more often (7.3% vs. 3.1% for PCI, P &lt; 0.01). In real-life practice with long-term follow-up, none of the two revascularization modalities implemented following HT decisions showed overwhelming superiority: occurrence of death and MI were similar, rates of RR favoured CABG, while incidence of strokes advocated PCI.

A Search for intermediate Mass Star-Forming Regions Within One KPC of the Sun

The incidence and potential mechanism of side-branch occlusion after implantation of bioresorbable scaffolds: Insights from ABSORB II

Despite advances in interventional technology, the incidence of postprocedural cardiac marker elevation has not substantially decreased since the first serial assessment 20 years ago. As of now, these postprocedural cardiac marker elevations are considered to represent periprocedural myocardial injury (PMI) with worse long-term outcome potential.

901-21 Percutaneous Vascular Surgery: Suture Mediated Percutaneous Closure of Femoral Artery Access Site Following Coronary Intervention

A new device (prostarTm, Perclose, Inc.) was developed to close femoral artery access sites percutaneously following coronary interventions in fully anticoagulated patients. The catheter deploys four needles with two pairs of sutures around the hole of femoral artery access sites. The sutures are then tied to close the arteriotomy site mechanically to achieve immediate hemostasis. As a pilot phase, the device was tested in six centers. The device was used immediately following coronary intervention in 91 access sites. Despite an average ACT at the time of the procedure of &gt;300 seconds, immediate complete hemostasis was achieved in 82 sites (90%). The devices were not appropriately positioned in 8 cases and procedures were aborted followed by reinsertion of a sheath or manual compression. Two patients (2.2%) required surgical repair of the femoral artery; one with device mechanical failure and one with bleeding from the initial puncture site in the posterior wall despite successful closure of the sheath site in the front wall. There were no AV fistulae or pseudoaneurysms requiring surgery and no infection, distal embolism or need for blood transfusion. In conclusion, this pilot study suggests that this suture mediated closure device appears to provide safe and effective hemostasis at the femoral access site in fully anticoagulated patients following coronary interventions.

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Is intravascular ultrasound after coronary stenting a safe procedure? Three cases of stent damage attributable to ICUS in a tantalum coil stent

The use of coronary stents decreases the morbidity associated with acute closure and restenosis after balloon angioplasty. Intracoronary ultrasound (ICUS) guidance of stent implantation has been advocated to improve stent deployment and thereby to further improve the clinical outcome after stenting, over and above balloon angioplasty. Whereas the merits of intracoronary ultrasound in this respect still remain to be proven, the present paper illustrates that ICUS itself may also entail complications. This paper repoorts on three cases of stent damage induced or aggravated by the ICUS procedure. Cathet. Cardiovasc. Diagn. 40:265–270, 1997. © 1997 Wiley-Liss, Inc.

Respiratory Pharmacology

Technology Insight: an overview of research in drug-eluting stents

No abstract is provided for this article.