Bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly, with an incidence on the world population between 0.9% and 2%. It is characterized by a morphologically normal leaflet and by the fusion of the other two leaflets into a large leaflet that covers about two thirds of the aortic annulus. This geometric configuration increases the risk of various pathologies: aortic insufficiency, aortic stenosis, and early development of ascending aorta aneurysm. These pathologies require surgical treatment; when the aorta is affected but the valve function is preserved, the elective approach consists in valve-sparing techniques. These replace the aortic wall, including the root, with a prosthetic graft and preserve the native valve, which is positioned inside the graft and stitched to it. In particular, the David sparing technique offers the advantage of stabilizing the aortic annulus, thus preventing long-term annular dilations. In this scenario, it has been proposed to reposition the commissures of the valve in when housing it in the graft, so that the normal and the fused leaflet would each span a 180° angle. Indeed, it has been hypothesized that this manipulation may be beneficial to the fluid dynamics across the valve and downstream of it. However, it may be speculated that this same manipulation may induce stress overloads on the valve leaflets. In this work, we used finite element modeling to simulate this surgical approach on an image-based model of the aortic root, and we compared the associated biomechanical impact to that of a standard sparing surgery with no commissural repositioning. Our results suggest that the commissures repositioning has led to several advantages in the valvular dynamic, whereas an overstress was found on the physiological leaflet. This aspect needs more in-depth studies for the long-term effects analysis on the patient.
La valvola aortica bicuspide (BAV) è l’anomalia congenita cardiaca più comune, con un’incidenza sull’intera popolazione mondiale compresa tra lo 0.9% ed il 2%. Essa è caratterizzata da un lembo fisiologico e due lembi fusi in un unico grande lembo che spazza circa i due terzi dell’annulus aortico. Questa configurazione aumenta il rischio di diverse patologie: insufficienza aortica, stenosi aortica, sviluppo precoce di aneurisma dell’aorta ascendente. Tutte queste patologie richiedono trattamento chirurgico; quando interessano l’aorta ma non la valvola, il trattamento d’elezione consiste nelle tecniche di sparing valvolare. Esse prevedono la sostituzione di radice ed ascendente con un graft sintetico e la conservazione della valvola nativa, che viene rialloggiata all’interno del graft e suturata ad esso. Tra queste, la tecnica di David ha il pregio di stabilizzare l’annulus aortico riducendo il rischio di sue dilatazioni sul lungo termine. In questo contesto, in caso di pazienti affetti da BAV è stato proposto di rialloggiare la valvola nel graft protesico riposizionandone le commissure in posizioni diametralmente opposte, così che il lembo fisiologico e il lembo generato dalla fusione spazzino ognuno un angolo di 180°. Si ipotizza che questa configurazione più simmetrica possa migliorare la fluidodinamica trans-valvolare e quella a valle della valvola. Allo stesso tempo, però, è ipotizzabile che questa manipolazione chirurgica possa indurre sovrasollecitazioni nei lembi valvolari. In questo lavoro, tramite simulazioni ad elementi finiti l’impatto strutturale di questo trattamento chirurgico è stato quantificato e confrontato con quello della chirurgia senza riposizionamento delle commissure. I risultati computazionali hanno evidenziato che il riposizionamento delle commissure ha portato a diversi vantaggi nella dinamica valvolare, mentre è stata riscontrata una sovrasollecitazione sul lembo fisiologico che necessita di studi maggiormente approfonditi per l’analisi degli effetti sul paziente a lungo termine.
Riparazione di valvola aortica bicuspide tramite tecniche di sparing : analisi computazionale degli effetti del riposizionamento a 180° delle commissure sulla biomeccanica valvolare
CAPPELLETTI, MARICA;Berardi, Federica
2020/2021
Abstract
Bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly, with an incidence on the world population between 0.9% and 2%. It is characterized by a morphologically normal leaflet and by the fusion of the other two leaflets into a large leaflet that covers about two thirds of the aortic annulus. This geometric configuration increases the risk of various pathologies: aortic insufficiency, aortic stenosis, and early development of ascending aorta aneurysm. These pathologies require surgical treatment; when the aorta is affected but the valve function is preserved, the elective approach consists in valve-sparing techniques. These replace the aortic wall, including the root, with a prosthetic graft and preserve the native valve, which is positioned inside the graft and stitched to it. In particular, the David sparing technique offers the advantage of stabilizing the aortic annulus, thus preventing long-term annular dilations. In this scenario, it has been proposed to reposition the commissures of the valve in when housing it in the graft, so that the normal and the fused leaflet would each span a 180° angle. Indeed, it has been hypothesized that this manipulation may be beneficial to the fluid dynamics across the valve and downstream of it. However, it may be speculated that this same manipulation may induce stress overloads on the valve leaflets. In this work, we used finite element modeling to simulate this surgical approach on an image-based model of the aortic root, and we compared the associated biomechanical impact to that of a standard sparing surgery with no commissural repositioning. Our results suggest that the commissures repositioning has led to several advantages in the valvular dynamic, whereas an overstress was found on the physiological leaflet. This aspect needs more in-depth studies for the long-term effects analysis on the patient.File | Dimensione | Formato | |
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2022_04_Berardi_Cappelletti_01.pdf
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https://hdl.handle.net/10589/186943