A nine months follow-up study of hemodynamic effect on bioabsorbable coronary stent implantation

Coronary artery disease has emerged as one of the major diseases causing death worldwide. Coronary stent has great effect to improve blood flow to the myocardium subtended by that artery, in which bioresorbable vascular scaffolds are new-generation stents used by people. However, Coronary stents implantation has a risk of restenosis, which is relative to hemodynamic parameters. Most of existing literatures studied in this issue have not taken into account such important factors as the strut thickness and lumen profile, and has yet to analyze the time effects among hemodynamic parameters over a certain period of time based on individual models. In this research, we proposed a framework to assess the chronic impact of hemodynamic on coronary stent implantation. In the framework, the optical coherence tomography (OCT) is combined with angiography to reconstruct patient-specific models of bioresorbable vascular scaffolds. Then, the hemodynamics parameters are extracted through the simulated 3D models, obtaining the distribution of wall shear stress (WSS), relative residence time (RRT) and oscillatory shear index (OSI). Finally, the changes of these parameters representing the effectiveness of hemodynamics exerted on the implanted stent can be assessed to estimate the chronic impacts. By a 9-month follow-up case study, it is observed that the difference of hemodynamic parameters are not significance. Both at baseline and 9-month follow-up experiments show that the hemodynamic parameters remain normal and similar, proving that the coronary stent implantation nowadays appears to have a robust and everlasting curative effect

Drug Eluding Stents for Malignant Airway Obstruction: A Critical Review of the Literature

Lung cancer being the most prevalent malignancy in men and the 3rd most frequent in women is still associated with dismal prognosis due to advanced disease at the time of diagnosis. Novel targeted therapies are already on the market and several others are under investigation. However non-specific cytotoxic agents still remain the cornerstone of treatment for many patients. Central airways stenosis or obstruction may often complicate and decrease quality of life and survival of these patients. Interventional pulmonology modalities (mainly debulking and stent placement) can alleviate symptoms related to airways stenosis and improve the quality of life of patients. Mitomycin C and sirolimus have been observed to assist a successful stent placement by reducing granuloma tissue formation. Additionally, these drugs enhance the normal tissue ability against cancer cell infiltration. In this mini review we will concentrate on mitomycin C and sirolimus and their use in stent placement

Vascular Healing after Coronary Stenting Evaluated by Optical Coherence Tomography

Optical coherence tomography (OCT) is a novel intracoronary imaging application for the assessment of native lesions and coronary stents. The purpose of this thesis was to evaluate the safety and feasibility of frequency-domain OCT (FD-OCT) based on experiences of the Satakunta Central Hospital (I). Early vascular healing was evaluated after implantation of endothelial progenitor cell capturing (II) and bio-active titanium-nitride-oxide coated stents (III) in two studies, each with 20 patients. Vascular healing was also compared after implantation of bio-active and everolimus-eluting stents on 28 patients after 9-month follow-up (IV). Long-term vascular healing of bio-active and paclitaxel-eluting stents was assessed in the last study with 18 patients (V). The results indicate that FD-OCT is safe and feasible (I). Both bio-active and endothelial progenitor cell capturing stents showed near-complete endothelialisation after one-month follow-up, which is desirable when prolonged dual anti-platelet therapy needs to be avoided after stenting (II and III). Endothelialisation of bio-active stents showed a predictable pattern at mid-term and long-term follow up (IV and V). Endothelialisation of everolimus-eluting stents was not complete at 9 months follow-up, which may suggest that interruption of dual antiplatelet therapy at this time point may not be safe (IV). Finally, delayed vascular healing may be present in patients treated with paclitaxel-eluting stents as long as 4 years from implantation, which reinforces the previously raised concerns on the long-term safety of this device (V).Sepelvaltimon paranemisen arvioiminen valokerroskuvauksella stenttauksen jälkeen Valokerroskuvaus on uusi suonensisäinen kuvantamismenetelmä sepelvaltimoiden ja sepelvaltimostenttien tutkimiseen. Väitöskirjatyön tarkoituksena oli arvioida menetelmän turvallisuutta ja käyttökelpoisuutta Satakunnan keskussairaalan kokemusten perusteella (I). Suonen varhaista paranemista arvioitiin endoteelisolujen esiasteita houkuttelevan stentin (II) sekä bioaktiivisen, titaanityppioksidilla päällystetyn stentin (III) asennuksen jälkeen kahdessa osatyössä, joissa kummassakin oli 20 potilasta. Verisuonen paranemista verrattiin myös bioaktiivisen stentin sekä everolimuusia vapauttavan lääkestentin välillä 9 kuukauden seurannan jälkeen 28 potilaalla (IV). Suonen pitkäaikaisparanemista verrattiin bioaktiivisen stentin ja paklitakselia vapauttavan lääkestentin välillä 18 potilaalla (V). Tulokset osoittavat, että sepelvaltimon valokerroskuvaus on turvallinen ja käyttökelpoinen (I). Sekä bioaktiivinen että endoteelisolujen esiasteita houkutteleva stentti endotelisoituivat lähes täydellisesti kuukaudessa, mikä on edullista, jos pitkäkestoista verihiutaleiden kaksoisestolääkitystä halutaan välttää (II ja III). Bioaktiivinen stentti endotelisoitui ennustettavalla tavalla keskipitkän ja pitkän seuranta-ajan jälkeen (IV ja V). Everolimuusia vapauttavan stentin endotelisaatio ei ollut täydellistä 9 kuukauden seurannassa, mikä voi viitata siihen, ettei verihiutaleiden kaksoisestolääkityksen keskeyttäminen tässä vaiheessa ole turvallista (IV). Lopuksi, verisuonen viivästynyttä paranemista todettiin jopa neljän vuoden kuluttua paklitakselia vapauttavan stentin asennuksesta, mikä vahvistaa aiemmin heränneitä epäilyjä tämän stentin turvallisuudesta (V).Siirretty Doriast

Implantation of bioresorbable scaffolds under guidance of optical coherence tomography: Feasibility and pilot clinical results of a systematic protocol

Background: Herein is hypothesised that a comprehensive optical coherence tomography (OCT)-guided implantation protocol for bioresorbable scaffolds (BRS) can improve expansion and apposition, thus resulting in better clinical outcomes, particularly in reducing thrombotic events.Methods: Patients considered suitable for BRS therapy in de novo coronary lesions underwent OCT. The predominant type of plaque was classified as lipidic, fibrous or calcific. Accordingly they underwent tailored plaque preparation. After proper sizing, BRS was deployed and final OCT was acquired. Post-dilation was performed only in cases of suboptimal deployment. Procedural and 12 month clinical follow-up is reported.Results: Twenty nine patients (41 lesions) who were considered clinically and angiographically suitable for BRS were enrolled, including challenging clinical scenarios such as ST-segment elevation myocardial infarction or CTOs. The OCT-guided protocol was feasible in 90.2% of the lesions: 14 (37.8%) lipidic, 11 (29.7%) fibrous, and 12 (32.4%) calcific. Three (8%) lesions classified as calcific were changed to treatment with metallic stent. BRS were implanted in 34 (91.9%) lesions, thereof 30 (88.2%) with optimal deployment in OCT. One (3.6%) periprocedural MI occurred, resulting in 3.6% target vessel failure and 0% scaffold thrombosis of any kind after a 12 month follow-up.Conclusions: OCT-guided BRS implantation is feasible in 90.2% of de novo lesions and results in optimal expansion and apposition, correlating with 3.6% incidence of target vessel failure and 0% scaffold thrombosis at 12 m follow-up, probably due to better selection of lesions amenable for BRS treatment and to a possibility of tailoring intervention to the type of plaque. These encouraging pilot results require confirmation in larger clinical studies

Drug Eluting Stent Implantation for High Risk Patients and Novel Technologies in Percutaneous Coronary Intervention

Percutaneous coronary intervention is a major treatment strategy for patients with coronary artery disease, and currently coronary stents are widely used in the world.1 Although stent implantation itself has shown to reduce restenosis by preventing both early elastic recoil and late vascular remodeling compared to balloon angioplasty, in-stent restenosis (ISR) still occurs in 10-40% of patients and has been the ‘Achilles’ heel’ of coronary interventions, frequently resulting in repeated revascularization.2,3 Restenosis after coronary stenting occurs secondary to the accumulation of smooth muscle cells and extracellular matrix proteoglycans.4 Despite the sophistication of the new techniques and enormous advance in devices, ISR requiring repeat procedure has been considered as a main limitation of coronary stenting. The advent of drug eluting stents (DES), which consist of a drug (immunosuppressive or antiproliferative drug), a polymer and a metallic platform, has revolutionized the practice of interventional cardiology by significantly reducing the rates of restenosis and repeat revascularization as compared to bare metal stents.5 After the first approval of DES, a large number of patients with coronary artery disease have undergone percutaneous revascularization with DES. However, many trials conducted in the ‘real world’ showed that the problem of restenosis was not completely resolved and still persists. Effect of DES for patients at high risk for ISR, such as acute myocardial infarction, small coronary vessels, aorto-ostial lesions, or lesions of chronic total occlusion (Part 1 of this thesis), have not been fully investigated. In addition, certain potential safety concerns regarding the widespread use of DES have arisen. The most notable drawback of DES is that they could increase the risk of thrombotic complication, especially late stent thrombosis6, although its incidence is low.7 The increased risk of thrombosis with DES utilization may be associated with altered endothelial function8 and/or delayed vascular healing9 induced by cytotoxic and cytostatic drug use. Localized hypersensitivity reactions to the polymer coating of DES and drug itself may also contribute to stent thrombosis.10 To retain the positive clinical aspects of DES and overcome their drawbacks, new concept stents have been developed (Part 2 of this thesis)