Biomechanical drawbacks of different techniques of mitral neochordal implantation: When an apparently optimal repair can fail.

OBJECTIVES: 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.

Is it possible to assess the best mitral valve repair in the individual patient? Preliminary results of a finite element study from magnetic resonance imaging data.

OBJECTIVES: Finite element modeling was adopted to quantitatively compare, for the first time and on a patient-specific basis, the biomechanical effects of a broad spectrum of different neochordal implantation techniques for the repair of isolated posterior mitral leaflet prolapse. METHODS: Cardiac magnetic resonance images were acquired from 4 patients undergoing surgery. A patient-specific 3-dimensional model of the mitral apparatus and the motion of the annulus and papillary muscles were reconstructed. The location and extent of the prolapsing region were confirmed by intraoperative findings, and the mechanical properties of the mitral leaflets, chordae tendineae and expanded polytetrafluoroethylene neochordae were included. Mitral systolic biomechanics was simulated under preoperative conditions and after 5 different neochordal procedures: single neochorda, double neochorda, standard neochordal loop with 3 neochordae of the same length and 2 premeasured loops with 1 common neochordal loop and 3 different branched neochordae arising from it, alternatively one third and two thirds of the entire length. RESULTS: The best repair in terms of biomechanics was achieved with a specific neochordal technique in the single patient, according to the location of the prolapsing region. However, all techniques achieved a slight reduction in papillary muscle forces and tension relief in intact native chordae proximal to the prolapsing region. Multiple neochordae implantation improved the repositioning of the prolapsing region below the annular plane and better redistributed mechanical stresses on the leaflet. CONCLUSIONS: Although applied on a small cohort of patients, systematic biomechanical differences were noticed between neochordal techniques, potentially affecting their short- to long-term clinical outcomes. This study opens the way to patient-specific optimization of neochordal techniques.

Functional mitral regurgitation: a 30-year unresolved surgical journey from valve replacement to complex valve repairs.

Functional mitral regurgitation remains one of the most complex and controversial aspect--for both clinicians and surgeons--in the management of mitral valve disease in the context of left ventricular dysfunction. Given the current absence of clear guidelines, as well as of results from randomized trials comparing the outcome of different surgical strategies potentially available for this complex scenario, surgical decision making for these high-risk patients poses a real dilemma in the daily practice. The resulting surgical choices often represent a questionable combination of surgeons' personal feeling, local supplies, patients' life expectancy and risk/benefit ratios, opinions and statements of the experts, and so on. This review provides an overview of the present knowledge about the complex pathophysiology underlying functional mitral regurgitation, the different pathophysiology-guided surgical techniques suggested in the last decades, as well as the current results following these different surgical techniques.

In which patients is transcatheter aortic valve replacement potentially better indicated than surgery for redo aortic valve disease? Long-term results of a 10-year surgical experience.

BACKGROUND: Redo aortic valve replacement procedures have been reduced by the growing practice of trans-catheter aortic valve-in-valve procedures. We analyzed our long-term results of redo aortic valve replacement procedures during a 10-year period in an effort to define subgroups in which trans-catheter aortic valve-in-valve procedures may be better than surgery. METHODS: From 2002 to 2010, 131 redo aortic valve replacement procedures with at least 18 months of follow-up were prospectively enrolled. Hospital and follow-up outcome of the entire population and of high-risk subgroups were evaluated. RESULTS: Hospital mortality was 2.3%, major re-entry complications were seen in 1.5%, re-exploration for bleeding was seen in 9.2%, perioperative low cardiac output state (ie, low cardiac output syndrome) was seen in 9.9%, stroke was seen in 3.1%, prolonged ventilation was seen in 18.3%, pneumonia was seen in 4.6%, acute renal insufficiency was seen in 11.5%, intra-aortic counterpulsation (intra-aortic balloon pump) was seen in 9.2%, renal replacement therapy was seen in 4.6%, need for transfusions was seen in 60.3%, and permanent pacemaker implantation was seen in 2.3%. One hundred twenty-month actuarial survival, freedom from acute heart failure, reinterventions, stroke, and thromboembolisms were 61.5% ± 8.6%, 62.9% ± 6.9%, 97.8% ± 1.5%, 93.2% ± 3.0%, and 91.2% ± 3.2%, respectively. Patients aged >75 years had similar outcome to younger patients (nonsignificant P for all). Endocarditis resulted in higher hospital mortality (P = .034), low cardiac output state (P < .0001), intra-aortic balloon pump (P < .0001), prolonged ventilation (P = .011), pneumonia (P = .049), acute renal insufficiency (P = .004), lower actuarial survival (log-rank P = .0001), freedom from acute heart failure (P = .002), and re-intervention (P = .003). New York Heart Association functional class IV at admission resulted in a higher incidence of low cardiac output state (P < .0001), intra-aortic balloon pump (P = .0001), prolonged ventilation (P < .0001), pneumonia (P = .015), and a lower actuarial freedom from re-intervention (P = .0001). Higher need for permanent pacemaker implantation (P = .015) and lower freedom from acute heart failure (P = .019) emerged after urgencies/emergencies. CONCLUSIONS: Redo aortic valve replacement procedures achieves good results, especially in nonendocarditic or elective cases, and young or New York Heart Association functional class I/II patients. Indeed, endocarditis significantly affects outcome. New York Heart Association functional class IV and nonelective procedures might benefit from trans-catheter aortic valve-in-valve procedures.