PENGARUH DESAIN GEOMETRI STENT TERHADAP TEGANGAN GESER DINDING DI PEMBULUH DARAH PERCABANGAN

NAHAR TAUFIQ, Prof. dr. Marsetyawan HNES., M.Sc., Ph.D; Ir. Alva Edy Tontowi, M.Sc., Ph.D; Prof. Dr. dr. Budi Yuli Setianto, Sp.PD(K), Sp.JP(K)

2019 | Disertasi | DOKTOR BIOTEKNOLOGI

Latar Belakang. Prosedur Intervensi Koroner Perkutan (IKP) di lesi percabangan pembuluh darah koroner terdapat masalah 30% karena penyempitan ulang stent dan trombosis stent. Luas sel strut stent berperan menjaga keseimbangan antara terbukanya muara cabang dan mencegah prolap plak. Desain geometri stent pembentuk luas sel strut berpengaruh terhadap aliran. Tegangan Geser Dinding (TGD) mencerminkan hemodinamik aliran dalam proses penyempitan ulang stent dan trombosis stent. Tujuan penelitian ini mencari pengaruh faktor desain geometri stent pembentuk luas sel strut terhadap TGD optimal dan menyusun desain geometri stent baru untuk menghasilkan TGD optimal, serta mencari hubungan antara rasio (luas permukaan strut: luas seluruh permukaan sel) dengan persentase luas dinding pembuluh darah yang memiliki TGD optimal. Metode dan Cara Penelitian. Penelitian dilakukan secara in-silico. Faktor desain geometri stent diukur dari stent komersial sebagai sample penelitian. Metode Taguchi dengan matriks faktor dan level dari desain geometri stent digunakan untuk menentukan jumlah rekayasa desain stent. Setiap rekayasa desain stent diimplantasikan di pembuluh darah percabangan menggunakan 2 stent. Analisis dinamika fluida (ADF) dilakukan secara komputasi dan respon diharapkan adalah persentase luas dinding dengan TGD 1-7 Pa di dinding pembuluh utama, dinding sisi luar cabang, dan dinding sisi dalam cabang. Hasil Penelitian. Perhitungan Process Capability Ratio Technique for Order Preference by Similarity to Ideal Solution (PCR-TOPSIS) dilakukan analisis varian menunjukkan jumlah simpul-konektor, panjang cincin, jarak spasi cincin dan tipe hubungan konektor sebagai pembentuk luas sel strut berpengaruh terhadap TGD optimal di percabangan. Masing-masing memberikan kontribusi 32,26% dari jarak spasi cincin; 24,58% dari panjang cincin; 20,30% dari jumlah simpul-konektor; 9,52% dari tipe hubungan konektor. Desain geometri stent baru adalah jumlah simpul-konektor 8-2, panjang cincin 1440 mikromilimeter, jarak spasi cincin 150 mikromilimeter dan jenis hubungan konektor adalah tipe tengah-tengah. Terdapat hubungan antara rasio (luas permukaan strut: luas seluruh permukaan sel) dengan persentase luas dinding pembuluh darah yang memiliki TGD optimal, dengan p=0,016 dan nilai koefisiensi 0,944. Kesimpulan. Faktor desain geometri stent pembentuk luas sel strut, yaitu jumlah simpul-konektor, panjang cincin, jarak spasi antar cincin dan hubungan konektor tengah-tengah berperan dalam menghasilkan TGD optimal. Tersusun desain stent baru yaitu jumlah simpul-konektor 8-2, panjang cincin 1440 mikromilimeter, jarak spasi cincin 150 mikromilimeter serta tipe hubungan konektor tengah-tengah. Terdapat hubungan antara rasio (luas permukaan strut: luas seluruh permukaan sel) dengan luas dinding pembuluh darah yang memiliki TGD optimal, p=0,016 dan nilai koefisiensi 0,944. Kata kunci: sel strut, desain geometri stent, tegangan geser dinding, percabangan pembuluh darah. 1. Sekolah Pascasarjana UGM. 2. Departemen Kardiologi Kedokteran Vaskuler, FK-KMK UGM.

Background. The Percutaneous Coronary Intervention Procedure (PCI) in the coronary bifurcation lesions leaves 30% problem due to intra-stent restenosis and thrombosis. Specific lesions of stenosis require specific stents. The design of the stent geometry has an effect on hemodynamics flow. The availability of coronary stents is universal. After PCI in vascular bifurcation lesions, the Wall Shear Stress (WSS) reflects hemodynamic flow which plays a role in the occurrence of intra-stent restenosis and thrombosis. The cell size formed by several geometric design factors is very likely to play a role in producing optimal WSS. The aim of this study was to find out the influence of factors from the design of the cell-forming stent geometry to the optimal WSS and to design a new stent geometry to produce optimal WSS and to find the relationship between the ratio of strut surface area: the entire cell surface area with surface area in optimal WSS. Research Methods. The study was conducted In-Silico. Measurements were made from each of stent geometry design factor from the most usage of stent geometry commercial in Indonesia. The Taguchi method with a factor matrix and the level of geometry design is used to determine the number and formulas of geometric design factor engineering. Stent implantation was done in virtual branching vessels. The fluid dynamics analysis (ADF) was carried out computationally and the expected response was the percentage of the wall area in the main vessel, on the outside of the branch and on the inside of the branch with the WSS target of 1-7 Pa. Research results. The calculation of Process Capability Ratio Technique for Order Preference by Similarity to Ideal Solution (PCR-TOPSIS) carried out Analysis of Variants obtained the number of connectors, ring length, ring spacing and connector connection type as cell-width forming influenced the optimal WSS in branching. Each contributes 32.26% of the distance of the ring space; 24.58% of ring length; 20.30% of the number of connectors; 9.52% of the connector connection type. The new geometry design was the number of 8-2 connectors, 1440 mikromilimeter ring length, 150 mikromilimeter ring spacing and the connector connection type were Middle-type. There was a relationship between the ratio of strut surface area: the total area of the cell surface with the surface wall area with optimal WSS, with p = 0.016 and coefficient of 0.944. Conclusion. The number of 8-2 connectors, 1440 mikromilimeter ring lengths, 150 mikromilimeter ring spacing and the Middle-type connector connection were play a role in the optimal WSS in the bifurcation. There was a relationship between the ratio of strut surface area: the total surface area of the cell with optimal WSS surface area, with a value of p = 0.016 and coefficient of 0.944. Keywords: cell area, stent geometry design factor, wall shear stress, bifurcation. 1. Interdisciplinary Postgraduate School UGM. 2. Vascular Cardiology Medicine Department, FK-KMK UGM.

Kata Kunci : cell area, stent geometry design factor, wall shear stress, bifurcation