Anomalous Aortic Origin of the Coronary Artery (AAOCA) from the aorta is a congenital condition and is a major trigger of sudden cardiac death (SCD) in athletes and soldiers, while it can remain silent for life for most of the sedentary and nonsports population. The sudden death hypothesis is due to the abnormal course of the artery, which may be subject to under-stress compression. Surgical treatment aims to remove or resolve this abnormality; there are several intervention techniques, some more invasive than others (e.g., unroofing, reimplantation, osteoplasty patch), but all have the goal of creating a new ostium in an anatomically and physiologically correct position. An as yet unresolved unknown is which of the above techniques is the best and which intervention restores the most physiological coronary flow possible. This thesis aims to create a tool to support the surgeon, which can identify the best practice on that type of surgery for that specific patient, and - in case of doubts regarding the way forward - what are the differences between the various interventions and which of those is the best. The study thus aims to provide a useful tool for the prediction of possible postoperative scenarios. So how can the different postoperative scenarios be predicted? In this thesis, fluid dynamic variables such as: flow, pressure drop, and shear stress (WSS) were examined. This decision-making tool is based on a parametric CAD (Computer Aided Designed) model built based on preoperative morphological data. The key points of the model are aortic root and healthy coronary artery that will remain unchanged, and sections of the AAOCA on which the post-surgery vessel construction will be based. Initially, the idea was approached through the construction in Grasshopper (plug in of Rhinoceros6 software) of an ideal model later used in fluid dynamic simulations (CFD) performed through the software SimVascular 22.07.20. The construction of this general model and the following analyses were key steps in the execution of sensitivity studies necessary to create the basis for the final practice of the patient-specific study. The validation was possible due to the collaboration of the Università degli Studi di Pavia with IRCCS Policlinico San Donato. The study was therefore divided into two main sections: an initial part of ideal model analysis, and a second part concerning the validation of the method. The results coming from the ideal model led to the observation of better values after the application of the patch practice; in fact, comparing the three postoperative results with the healthy case, it was possible to observe, for example, that: in terms of Euclidean distance, patching is the practice that best approximates normal physiology (observing the flow, a distance of 8. 499 mL/min vs 11,475 mL/min and 17,178 mL/min of reimplantation and unroofing, respectively); in terms of percentage difference, an improvement of ≈ 91% in terms of total flow (compared with ≈ 88% of reimplantation, and ≈ 82% of unroofing), and ≈ 94% in terms of total pressure (compared with ≈ 93% of reimplantation, and ≈ 86% of unroofing) could be observed. The present study thus provides a clinician-supported decision-making tool that can simulate different surgeries so that the technique that can return the best results at the fluid dynamic level can be identified. Its applicability was demonstrated in the second part of the discussion, where it was possible to compare the results from CFD simulations with results from actually applied surgery.
L’origine anomala delle arterie coronarie dall’aorta (AAOCA) ha natura congenita e rappresenta una delle principali cause scatenanti morte cardiaca improvvisa (MCI) tra atleti e soldati, mentre può rimanere silente a vita per la maggior parte della popolazione sedentaria e non sportiva. L’ipotesi di morte improvvisa è dovuta al decorso anomalo dell’arteria, che può essere soggetta a compressione sotto sforzo. Il trattamento chirurgico mira a rimuovere o risolvere tale anomalia; esistono diverse tecniche di intervento, alcune più invasive di altre (e.g., unroofing, reimpianto, patch osteoplasty), ma tutte hanno come obiettivo la creazione di un nuovo ostio in posizione anatomicamente e fisiologicamente corretta. Un’incognita non ancora risolta è quale delle tecniche sopra citate è la migliore e quale sia l’intervento che permette di ristabilire il flusso coronarico più fisiologico possibile. Questa tesi si pone come obbiettivo la creazione di uno strumento a supporto del chirurgo, in grado di individuare la pratica migliore su quel tipo di chirurgia per quel paziente specifico, e – in caso di dubbi riguardanti la strada da percorrere – quali sono le differenze tra i diversi interventi e quale tra quelli in esame è il migliore. Lo studio si prefigge quindi l’obbiettivo di fornire uno strumento utile alla predizione dei possibili scenari post-operatori. Com’è possibile predire i diversi scenari? In questo trattato sono state esaminate variabili fluidodinamiche come: flusso, drop pressorio, e sforzo di taglio (WSS). Questo strumento decisionale si basa su un modello CAD (Computer Aided Designed) parametrico costruito sulla base di dati morfologici preoperatori. I punti fondamentali del modello sono radice aortica e coronaria sana che rimarranno inalterati, e le sezioni della coronaria anomala sulle quali si baserà la costruzione del vaso post-intervento. Inizialmente l’idea è stata affrontata attraverso la costruzione in Grasshopper (plug-in del software Rhinoceros6) di un modello ideale utilizzato poi nelle simulazioni fluidodinamiche (CFD) eseguite attraverso il software SimVascular. La costruzione di questo modello generale e le successive analisi sono stati passaggi fondamentali per lo svolgimento di studi di sensitività necessari per creare le fondamenta di quella che poi sarà la pratica definitiva dello studio patient-specific, la cui validazione sarà resa possibile grazie alla collaborazione dell’Università degli Studi di Pavia con l’IRCCS Policlinico San Donato. Lo studio è quindi stato diviso in due sezioni principali: una parte iniziale di analisi di modello ideale, e una seconda parte inerente alla validazione del metodo. I risultati provenienti dal modello ideale hanno portato ad osservare valori migliori dopo l’applicazione della pratica patch; infatti paragonando i tre risultati postoperatori con il caso sano, è stato possibile osservare ad esempio che: in termini di distanza euclidea, il patch è la pratica che meglio si avvicina alla fisiologia normale (osservando il flusso è possibile notare una distanza pari a 8.499 mL/min vs 11.475 mL/min e 17.178 mL/min di reimpianto e unroofing rispettivamente); in termini di differenza percentuale è stato possibile osservare un miglioramento del ≈ 91% in termini di flusso totale (rispetto al ≈ 88% di reimpianto, e ≈ 82% di unroofing), e del ≈ 94% in termini di pressione totale (rispetto al ≈ 93% di reimpianto, e ≈ 86% di unroofing). Il presente studio fornisce quindi uno strumento decisionale a supporto del clinico in grado di simulare i diversi interventi chirurgici, così da poter identificare la tecnica in grado di restituire i migliori risultati a livello fluidodinamico. La sua applicabilità è stata dimostrata nella seconda parte della trattazione, dove è stato possibile comparare i risultati provenienti dalle simulazioni CFD con quelli derivanti dalla chirurgia realmente applicata.
VALUTAZIONE DELL'EMODINAMICA POST-OPERATORIA PER LA PIANIFICAZIONE DEL TRATTAMENTO CHIRURGICO DI ARTERIE CORONARIE CON ORIGINE ANOMALA DALL’AORTA (AAOCA) ATTRAVERSO UN MODELLO COMPUTAZIONALE
ANGLESE, SERENA
2021/2022
Abstract
Anomalous Aortic Origin of the Coronary Artery (AAOCA) from the aorta is a congenital condition and is a major trigger of sudden cardiac death (SCD) in athletes and soldiers, while it can remain silent for life for most of the sedentary and nonsports population. The sudden death hypothesis is due to the abnormal course of the artery, which may be subject to under-stress compression. Surgical treatment aims to remove or resolve this abnormality; there are several intervention techniques, some more invasive than others (e.g., unroofing, reimplantation, osteoplasty patch), but all have the goal of creating a new ostium in an anatomically and physiologically correct position. An as yet unresolved unknown is which of the above techniques is the best and which intervention restores the most physiological coronary flow possible. This thesis aims to create a tool to support the surgeon, which can identify the best practice on that type of surgery for that specific patient, and - in case of doubts regarding the way forward - what are the differences between the various interventions and which of those is the best. The study thus aims to provide a useful tool for the prediction of possible postoperative scenarios. So how can the different postoperative scenarios be predicted? In this thesis, fluid dynamic variables such as: flow, pressure drop, and shear stress (WSS) were examined. This decision-making tool is based on a parametric CAD (Computer Aided Designed) model built based on preoperative morphological data. The key points of the model are aortic root and healthy coronary artery that will remain unchanged, and sections of the AAOCA on which the post-surgery vessel construction will be based. Initially, the idea was approached through the construction in Grasshopper (plug in of Rhinoceros6 software) of an ideal model later used in fluid dynamic simulations (CFD) performed through the software SimVascular 22.07.20. The construction of this general model and the following analyses were key steps in the execution of sensitivity studies necessary to create the basis for the final practice of the patient-specific study. The validation was possible due to the collaboration of the Università degli Studi di Pavia with IRCCS Policlinico San Donato. The study was therefore divided into two main sections: an initial part of ideal model analysis, and a second part concerning the validation of the method. The results coming from the ideal model led to the observation of better values after the application of the patch practice; in fact, comparing the three postoperative results with the healthy case, it was possible to observe, for example, that: in terms of Euclidean distance, patching is the practice that best approximates normal physiology (observing the flow, a distance of 8. 499 mL/min vs 11,475 mL/min and 17,178 mL/min of reimplantation and unroofing, respectively); in terms of percentage difference, an improvement of ≈ 91% in terms of total flow (compared with ≈ 88% of reimplantation, and ≈ 82% of unroofing), and ≈ 94% in terms of total pressure (compared with ≈ 93% of reimplantation, and ≈ 86% of unroofing) could be observed. The present study thus provides a clinician-supported decision-making tool that can simulate different surgeries so that the technique that can return the best results at the fluid dynamic level can be identified. Its applicability was demonstrated in the second part of the discussion, where it was possible to compare the results from CFD simulations with results from actually applied surgery.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/15369