Biomechanical drawbacks of different techniques of mitral neochordal implantation: When an apparently optimal repair can fail.
OBJECTIVE
Intraoperative assessment of the proper neochordal length during mitral plasty may be complex sometimes. Patient-specific finite element models were used to elucidate the biomechanical drawbacks underlying an apparently correct mitral repair for isolated posterior prolapse.


METHODS
Preoperative patient-specific models were derived from cardiac magnetic resonance images; integrated with intraoperative surgical details to assess the location and extent of the prolapsing region, including the number and type of diseased chordae; and complemented by the biomechanical properties of mitral leaflets, chordae tendineae, and artificial neochordae. We investigated postoperative mitral valve biomechanics in a wide spectrum of different techniques (single neochorda, double neochordae, and preconfigured neochordal loop), all reestablishing adequate valvular competence, but differing in suboptimal millimetric expanded polytetrafluoroethylene suture lengths in a range of ±2 mm, compared with the corresponding "ideal repair."


RESULTS
Despite the absence of residual regurgitation, alterations in chordal forces and leaflet stresses arose simulating suboptimal repairs; alterations were increasingly relevant as more complex prolapse anatomies were considered and were worst when simulating single neochorda implantation. Multiple chordae implantations were less sensitive to errors in neochordal length tuning, but associated postoperative biomechanics were hampered when asymmetric configurations were reproduced. Computational outcomes were consistent with the presence and entity of recurrent mitral regurgitation at midterm follow-up of simulated patients.


CONCLUSIONS
Suboptimal suture length tuning significantly alters chordal forces and leaflet stresses, which may be key parameters in determining the long-term outcome of the repair. The comparison of the different simulated techniques suggests possible criteria for the selection and implementation of neochordae implantation techniques.
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy; Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milano, Italy. Electronic address: francesco.sturla@polimi.it.
Francesco
F
Sturla
Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milano, Italy.
Emiliano
E
Votta
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy.
Francesco
F
Onorati
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy.
Konstantinos
K
Pechlivanidis
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy; Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milano, Italy.
Omar A
OA
Pappalardo
Department of Anesthesia, Università degli Studi di Verona, Verona, Italy.
Leonardo
L
Gottin
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy.
Aldo D
AD
Milano
Department of Radiology, Università degli Studi di Verona, Verona, Italy.
Giovanni
G
Puppini
Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milano, Italy.
Alberto
A
Redaelli
Division of Cardiovascular Surgery, Università degli Studi di Verona, Verona, Italy.
Giuseppe
G
Faggian
D001696:Biomechanical Phenomena; D002815:Chordae Tendineae / Q000473:pathology / Q000503:physiopathology / Q000637:transplantation*; D003198:Computer Simulation; D020342:Finite Element Analysis; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging; D008943:Mitral Valve / Q000473:pathology / Q000503:physiopathology / Q000637:transplantation*; D058386:Mitral Valve Annuloplasty / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D008944:Mitral Valve Insufficiency / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D008945:Mitral Valve Prolapse / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D008955:Models, Cardiovascular; D011138:Polytetrafluoroethylene; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012008:Recurrence; D012307:Risk Factors; D013536:Suture Techniques; D013537:Sutures; D017211:Treatment Failure
D011138:Polytetrafluoroethylene
finite element models; mitral neochordoplasty; mitral valve prolapse; mitral valve repair; suture length