SurgAid

The aim of the SurgAid project is to develop and apply new methods for diagnosis and support in mitral valve (MV) surgery repair procedures, based on the combined analysis and integration of the finite element modelling (FEM) approach with the quantification of 4D echocardiographic images by advanced image processing.

Severe MV regurgitation associated to degenerative MV prolapse is one of the most common valvular pathologies in the industrialized countries, and it is characterized by high morbidity and mortality. MV repair with annuloplasty (i.e., the insertion of a prothesic ring on the mitral annulus), is currently the primary surgical solution for this pathology. However, some clinical questions related to this approach are still unsolved:

• what are the ring characteristics able to maximize the benefit for the patient in the left ventricular (LV) remodeling phase following the intervention?
• how does the interaction of the ring with the sub-valvular apparatus (chordae tendinee and papillary muscles) influence the ring 3D morphology and dynamics in the short- and long-term?

The recent developments in ultrasound technology allow real-time 3D echocardiographic (E3D) imaging to be noninvasively obtained, thus providing an imaging modality potentially suitable for the quantification of useful information to reply to those questions. However, proper image processing methods able to reliably extract this 4D (3D+time) data are actually missing. On the other hand, finite element models of the MV could potentially help in the comprehension of the effect of pathophysiology on mechanical parameters, but they are currently based on in-vivo animal data or ex-vivo human measurements. Moreover, several simplifications on MV geometry and function have been introduced, thus limiting their clinical applicability.

The SurgAid project aims to overcome these limitations, by providing new image processing techniques in order to extract from E3D images novel quantitative information about MV annulus regional geometry and dynamics, papillary muscles position, LV global and regional shape. These tools will be applied to the analysis of 25 normal subject, together with at least 60 patients with mitral valve prolapse undergoing mitral valve repair procedure with annuloplasty, evaluated pre- and post-surgery (at 3 and 6 months). The obtained quantitative information will be utilized and integrated in order to create a realistic physiologic FEM of the MV (ie, thus overcoming previous limitations), to modify this model in order to simulate two pathologic conditions (segmental prolapse and Barlow syndrome), and different post-surgical scenarios, after insertion of annular rings with different structural and mechanical characteristics.

This combined approach is novel and unconventional, and will have important implications both in clinical practice and in the biomedical engineering field.

This project is both interdisciplinary (involving both electronic and mechanical biomedical engineering competences) and multi-disciplinary (in collaboration with heart surgeons, cardiologists and cardiac imaging technicians of the partner clinical institutions).

In fact, it will be realized by the collaboration or three research units (RU):

• Biomedical Engineering Dpt at the Politecnico di Milano (PoliMI RU) coordinated by Dr. Enrico Caiani, national coordinator of the whole project
• Medicine and Surgery Dpt at the Università degli Studi di Milano (UniMI RU), coordinated by Prof. Francesco Alamanni, operating at the Centro Cardiologico Monzino in Milano
• Electronics, Informatic and Systems Dpt at the Università di Bologna (UniBO RU), coordinated by Dr. Alessandro Sarti

These RUs have all the experience and knowledge to fully accomplish the expected goals. Also, a collaboration among them is already active on several research project, thus ensuring strong synergy to the project development. Moreover, the external collaboration of the Noninvasive Cardiac Imaging Laboratory at the University of Chicago Hospitals, coordinated by Dr. RM Lang, is foreseen. Both the POLIMI and UNIBO RUs have long-established links with this center, that will contribute providing a database of E3D images already acquired from a normal population, and in the phase of clinical interpretation of the results.