ALTIGEN BİRİM HÜCRELİ STENT TASARIMININ PERFORMANS ANALİZLERİ VE FDM İLE TEK KATMANLI ÜRETİLEBİLİRLİK ÇALIŞMASI

Öz

İlaç salınımlı stentlerden sonra geliştirilen biyobozunur polimer esaslı stentler için yapılan ön klinik çalışmalardan elde edilen sonuçlara göre polimer stentlerin kullanılabilirliği sorgulanmaktadır. Polimer stentlerde strat kalınlığının yüksek olması ve mekanik özelliklerin zayıflığı nedeniyle tasarım ve malzeme iyileştirmesine gidilerek yeni modellerin ortaya çıkarılması üzerine araştırmalara devam edilmektedir. Balonla genişleyen stentlerde oluşan uç açılması arter içerisinde intimal ve medial katmanlara zarar vermektedir. Bu zarar, erken dönemde neointimal hiperplazi ve restenoza sebep olmaktadır. Metalik stent geometrilerinden biri olan Palmaz-Schatz birim hücre modelinde balonla genişleme esnasında uç açılması ve kısalma oranı meydana gelmektedir. Bu çalışmada, Palmaz-Schatz stent geometrisinin genişlemesiyle oluşturduğu geometri dikkate alınarak PLLA malzemeden altıgen birim stent geometrisinde yeni tasarım gerçekleştirilmiştir. Sonlu elemanlar simülasyonuyla, ince strat kalınlığında tasarlanan altıgen stendin genişlemesinde oluşan uç açılması ve kısalma oranı belirlenmiştir. Ayrıca, stent genişlemesinde üç katmanlı arter ve kalsifik plak yapısında meydana gelen doku hasarı ölçülmüştür. Altıgen geometrideki stentte oluşan uç açılması ve kısalma oranı Palmaz-Schatz modeline göre azaltılmıştır. Bununla birlikte, PLA/PHA karışımı malzemeden eriyik yığma modelleme ile altıgen stent geometrisinin 3B plaka baskısı tek katmanlı olarak üretilmesi sonrası ısıtıcı bir tubular tabla üzerinde sarılarak stent formuna getirilmiştir

Anahtar Kelimeler

• Biyobozunur Stent
• Stent Tasarımı
• Uç Açılması
• Kısalma Oranı
• 3B Baskı

PERFORMANCE ANALYSIS OF HEXAGONAL UNIT CELL STENT DESIGN AND SINGLE-LAYERED MANUFACTURABILITY WITH FDM

Öz

The usability of polymer stents is questioned according to the results obtained from preliminary clinical studies for biodegradable polymer-based stents developed after drug-eluting stents. Due to the high strut thickness and weak mechanical properties of polymer stents, research continues on the creation of new models by improving the design and material. The dog-boning in balloon-expanded stents damages the intimal and medial layers within the artery. This damage causes neointimal hyperplasia and restenosis in the early period. During the balloon expansion of the Palmaz-Schatz unit cell model, which is one of the metallic stent geometries, dog-boning and foreshortening rates occur. In this study, a new design was carried out in hexagonal unit stent geometry from PLLA material, taking into account the geometry formed by the expansion of the Palmaz-Schatz stent geometry. The dog-boning and foreshortening ratio of the hexagonal stent designed in thin strut thickness was determined by finite element simulation. In addition, vessel injury in the three-layered artery and calcified plaque structure was measured during stent expansion. The dog-boning and foreshortening ratio of the stent with hexagonal geometry is reduced compared to the Palmaz-Schatz model. However, after the 3D printing of the hexagonal stent geometry was produced as a single layer by fused deposition modeling from PLA/PHA blends, it was wrapped on a heating tubular table and brought into the stent form.

Anahtar Kelimeler

• Biodegradable Stent
• Stent Design
• Dog-boning
• Foreshortening Ratio
• 3D Printing

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