Double orifice mitral valve

Abstract: Objectives: A 3D computational model has been implemented for the evaluation of the hemodynamics of the double orifice repair. Critical issues for surgical decision making and echo-Doppler evaluation of the results of the procedure are investigated. Methods: A parametric 3D computational model of the double-orifice mitral valve based on the finite elements model has been constructed from clinical data. Nine different geometries were investigated, corresponding to three total inflow areas (1.5, 2.25 and 3 cm 2 ) and to three orifice configurations (two equal orifices, two orifices of different areas, i.e. one twice as much the other one, and a single orifice). The simulations were performed in transit; the fluid was initially quiescent and was accelerated to the maximum flow rate with a cubic function. For each case, some characteristic values of velocity and pressure were determined : velocities were calculated downstream of each orifice, at the centre of it (V cen1 , V cen2 ). The maximum velocity was also determined for each orifice (V m V max2 ). Maximum pressure drops (ΔP max ) across the valve were compared with the estimations (Δp Bernoulli ) based on the Bernoulli formula (4 V 2 ). Results: In each simulation, no notable difference was observed between V cen1 and V cen2 , and between V and V regardless of the valve configuration. Maximum velocity and Δp max were related to the total orifice area and were not influenced by the orifice configuration. Δp Bernoulli calculated with V max was well correlated with the Δp max obtained throughout the simulations (y = 0.9126x + 0.3464, r = 0.996); on the contrary the pressure drops estimated using V underestimated (y = 0.6757x + 0.3073, r = 0.999) the actual pressure drops. Conclusions: The hemodynamic behaviour of a double orifice mitral valve does not differ from that of a physiological valve of same total area: pressure drops and flow velocity across the valve are not influenced by the configuration of the valve. Echo Doppler estimation of the maximum velocities is a reliable method for the calculation of pressure gradients across the repaired valve. © 1999 Elsevier Science B.V. All rights reserved.

Abstract: Objective: The ‘double-orifice’ (DO) technique has been recently proposed as an additional option in mitral valve repair (MVR). However, little is known regarding the long-term postoperative outcome and the predictors of DO results. Therefore, the aim of this study was to evaluate our clinical series and to identify prognostic factors of DO repair. Methods: From 1992, 75 patients underwent DO procedure because of severe mitral regurgitation. The study population consisted of 48 male and 27 female patients with a mean age of 58 ^ 13 years (range 16‐80 years). The aetiology of mitral incompetence was Barlow disease in 30 cases, rheumatic disease in 18 cases, acute or healed endocarditis in 16 cases and other causes in 11 cases. Carpentier rigid ring was used in 38 patients, whereas autologous pericardium was used in 24 patients. Thirteen patients had no annuloplasty procedure. Statistical analysis included univariate and multivariate Cox proportional models to evaluate the predictors of the DO failure. Results: There were four hospital and three late deaths with a survival rate of 92% at 8 years. Mean follow-up was 42 ^ 24 months (range 1‐93 months). Twelve patients underwent reoperation (five cases of early failure) and had valve replacement, leading to 80% freedom from reoperation at 8 years. At follow-up, 13 patients had no mitral regurgitation, 36 patients had trivial or mild mitral incompetence, whereas eight patients had moderate or severe mitral insufficiency at transthoracic echocardiography. Preoperative low left ventricular ejection faction, pulmonary arterial hypertension and marked left atrial enlargement were predictorsOP , 0:05U of DO failure at univariate analysis. Pericardial annuloplasty was also a risk factorOP , 0:05U for unsuccessful DO repair at long term. Cox proportional multivariate analysis confirmed left atrial dilatation, pulmonary hypertension and pericardial annuloplasty as independent predictors of unfavourable postoperative results. Conclusions: This study suggests that preoperative factors, like pulmonary hypertension and severe left atrial dilatation, may predict late DO failure. Our findings also indicate that pericardial annuloplasty may negatively influence mitral valve reconstruction at long term when DO is employed in MVR. q 2001 Elsevier Science B.V. All rights reserved.