Introduction: Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure that is emerging as a promising solution for the treatment of aortic stenosis. As part of the procedure, balloon post-dilatation aims to reduce the risk of paravalvular leakage by optimising the adhesion between the prosthesis and patient's aortic root. The aim of this work is to develop and validate a computational finite element (FE) model capable of reproducing this step in patients undergoing TAVI, and to evaluate any improvement in predicting the outcome of the procedure compared to simulations without post-dilation, used as a reference. Methods: A post-dilatation balloon model was reconstructed and three different simulations were carried out to reproduce deflation, crimping and inflation. The balloon was then integrated into patient-specific anatomical models reconstructed from preoperative CT images. In this study, two patients undergoing balloon post dilatation with implanted self-expandable valves were analysed. Subsequently, FE simulations of the post-dilatation were performed; in particular, two different configurations were investigated modelling calcifications as linear elastic or elasto plastic. Finally, model validation was based on qualitative and quantitative comparisons with post-operative clinical data, such as angiographies and CT images. Validation results were then used to assess any difference from the reference model. Results: A qualitative match between simulated and in vivo implanted stent configurations is evident from the superimposition of simulation results and angiographic images. Among all post-dilation simulations executed, the maximum and the minimum OA percentage differences between the final configuration of the simulated stent and segmented one are 2.33 ± 1.32 % and 1.14 ± 0.92 %; in terms of eccentricity, the maximum and minimum percentage error are 1.7301 % and 0.1112 %. Comparing these results with the simulations without post-dilatation, we obtain maximum improvements of 70 % and 75 % for OA and eccentricity respectively. Conclusion: In patients who underwent in vivo post-dilatation, simulating this phase is crucial. The significant error reduction observed in the analyzed cases highlights the importance of including this step, as its omission would introduce additional inaccuracies. Thus, incorporating post-dilatation represents a meaningful refinement to the developed TAVI in-silico model.
Introduzione: L’impianto valvolare aortico transcatetere (TAVI) è un intervento mininvasivo che si sta affermando come soluzione promettente per il trattamento della stenosi aortica. Nell’ambito dell’operazione, la procedura di post-dilatazione con palloncino è volta a ridurre il rischio di trafilamenti paravalvolari ottimizzando l’adesione tra la protesi e la radice aortica del paziente. Questo lavoro mira a sviluppare e validare un modello computazionale agli elementi finiti (FE) capace di riprodurre questo step in pazienti con impianto TAVI e a valutare l’eventuale miglioramento nel predire i risultati della procedura rispetto a simulazioni senza post dilatazione, prese come riferimento. Metodi: È stato ricostruito un modello di palloncino per post-dilatazione su cui sono state eseguite tre diverse simulazioni per riprodurne sgonfiaggio, crimping e gonfiaggio. Il palloncino è stato poi integrato in modelli anatomici paziente-specifici ricostruiti da immagini CT preoperatorie. In questo studio sono stati analizzati due pazienti sottoposti a post-dilatazione con palloncino post impianto di valvole autoespandibili. Su questi soggetti sono state eseguite simulazioni FE di post dilatazione; in particolare, sono state investigate due diverse configurazioni modellando le calcificazioni come elastiche lineari o elasto-plastiche. Infine, la validazione del modello si è basata su confronti qualitativi e quantitativi con dati clinici post-operatori, come angiografie e immagini CT. I risultati della validazione sono stati poi usati per valutare eventuali differenze rispetto al modello di riferimento. Risultati: Dalla sovrapposizione tra i risultati delle simulazioni e le immagini angiografiche emerge evidente una corrispondenza qualitativa tra la configurazione dello stent simulato e quello impiantato in-vivo. Tra tutte le simulazioni di post dilatazione eseguite, la massima e la minima differenza percentuale di OA tra le configurazioni finali dello stent simulato e di quello segmentato sono del 2.33 ± 1.32 % e dell’1.14 ± 0.92 %; in termini di eccentricità, il massimo e minimo errore percentuale sono 1.7301 % e 0.1112 %. Confrontando questi risultati con le simulazioni senza post dilatazione, si ottengono miglioramenti del 70 % e del 75 % rispettivamente per l’OA e per l’eccentricità. Conclusioni: Nei pazienti in cui è stata eseguita la post-dilatazione in-vivo, la simulazione di questa fase è cruciale. La significativa riduzione dell’errore osservato nei casi analizzati infatti evidenzia l’importanza di includere questo step poiché la sua omissione introdurrebbe inaccuratezze aggiuntive. In conclusione, l’inclusione della post-dilatazione nelle simulazioni definisce un buon raffinamento del già accurato modello in-silico precedente.
Modelli in silico di post-dilatazione in pazienti con impianto TAVI
Ruffino, Lorenzo;Merli, Chiara
2023/2024
Abstract
Introduction: Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure that is emerging as a promising solution for the treatment of aortic stenosis. As part of the procedure, balloon post-dilatation aims to reduce the risk of paravalvular leakage by optimising the adhesion between the prosthesis and patient's aortic root. The aim of this work is to develop and validate a computational finite element (FE) model capable of reproducing this step in patients undergoing TAVI, and to evaluate any improvement in predicting the outcome of the procedure compared to simulations without post-dilation, used as a reference. Methods: A post-dilatation balloon model was reconstructed and three different simulations were carried out to reproduce deflation, crimping and inflation. The balloon was then integrated into patient-specific anatomical models reconstructed from preoperative CT images. In this study, two patients undergoing balloon post dilatation with implanted self-expandable valves were analysed. Subsequently, FE simulations of the post-dilatation were performed; in particular, two different configurations were investigated modelling calcifications as linear elastic or elasto plastic. Finally, model validation was based on qualitative and quantitative comparisons with post-operative clinical data, such as angiographies and CT images. Validation results were then used to assess any difference from the reference model. Results: A qualitative match between simulated and in vivo implanted stent configurations is evident from the superimposition of simulation results and angiographic images. Among all post-dilation simulations executed, the maximum and the minimum OA percentage differences between the final configuration of the simulated stent and segmented one are 2.33 ± 1.32 % and 1.14 ± 0.92 %; in terms of eccentricity, the maximum and minimum percentage error are 1.7301 % and 0.1112 %. Comparing these results with the simulations without post-dilatation, we obtain maximum improvements of 70 % and 75 % for OA and eccentricity respectively. Conclusion: In patients who underwent in vivo post-dilatation, simulating this phase is crucial. The significant error reduction observed in the analyzed cases highlights the importance of including this step, as its omission would introduce additional inaccuracies. Thus, incorporating post-dilatation represents a meaningful refinement to the developed TAVI in-silico model.File | Dimensione | Formato | |
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2024_12_Merli_Ruffino_Tesi.pdf
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2024_12_Merli_Ruffino_ExecutiveSummary.pdf
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https://hdl.handle.net/10589/230434