New methods for diagnosis and support in mitral valve surgery repair procedures based on the integration of finite element modelling and 4D echocardiographic image processing


People involved: Alberto Redaelli, Emiliano Votta, Marco Stevanella

Funding source: Italian Research Ministry Grant

Grant number: PRIN-2007-B9B39B

Funding period: 2007 - 2009

Partners: Bioengineering Department, Politecnico di Milano; Medicine Faculty, Università degli Studi di Milano; Department of Electronics, Computer Sciences and Systems, Bologna University; Cardiology and Cardiac Surgery Divisions, Centro Cardiologico Monzino IRCCS; CILEA Consorzio Interuniversitario; University of Chicago.

Severe mitral valve (MV) regurgitation associated to degenerative MV prolapse is one of the most common valvular pathologies in the industrialized countries. It is characterized by high morbidity and mortality, and consists of the presence of a regurgitant blood flow towards the left atrium, causing dilation of the valvular orifice. Its aetiology is manifold and its development and effects vary considerably, in terms of both stability and required treatments.
MV repair, when technically possible, is currently the primary surgical solution in patients with insufficiency due to leaflets prolapse. As compared to MV replacement, it allows to preserve the whole sub-valvular apparatus and the continuity between the ventricular myocardium and the valvular plane, thus preserving the geometry and improving left ventricular (LV) function, thus increasing the long-term survival. Normally, MV repair includes annuloplasty, i.e. the insertion of an artificial ring to reshape the valvular orifice.
In the last 15 years, patients’ prognosis has been improving, thanks to the advances in echocardiographic imaging techniques, which provide more accurate diagnoses, to the availability of new surgical prostheses and techniques and to the development of useful guidelines for surgical planning. However, some questions regarding the performance of annuloplasty rings are still without a clear answer: what are the ring characteristics able to maximize the benefit for the patient in the left ventricular (LV) remodelling phase following the intervention? How does the interaction of the ring with the sub-valvular apparatus (chordae tendineae and papillary muscles) influence the ring 3D morphology and dynamics in the short- and long-term?
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. The recent developments in ultrasound technology allow real-time 3D echocardiographic (E3D) imaging to be non-invasively 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. The obtained quantitative information will be utilized and integrated in order to create realistic, patient-specific finite element models of the MV to analyse MV biomechanics in normal, pathological and post-operative conditions.