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Eur J Cardiothorac Surg 1999;15:419-425
© 1999 Elsevier Science NL

The hemodynamic effects of double-orifice valve repair for mitral regurgitation: a 3D computational model¹

^a Cardiac Surgery Department, IRCCS, San Raffaele Hospital, Via Olgettina 60, 20132, Milan, Italy
^b CEBITEC, Politecnico di Milano, Milan, Italy

Received 22 September 1998; received in revised form 27 January 1999; accepted 2 February 1999.

Corresponding author. Tel.: +39-2-2643-7109; fax: +39-2-2643-7125; e-mail: maisano.francesco@hsr.it

	Abstract

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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 cm²) 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_max1, V_max2). Maximum pressure drops (p_max) across the valve were compared with the estimations (p_Bernoulli) based on the Bernoulli formula (4 V²). Results; In each simulation, no notable difference was observed between V_cen1 and V_cen2, and between V_max1 and V_max2, regardless of the valve configuration. Maximum velocity and p_max were related to the total orifice area and were not influenced by the orifice configuration. p_Bernoulli calculated with V_max was well correlated with the p_max obtained throughout the simulations (y=0.9126x+0.3464, r=0.996); on the contrary the pressure drops estimated using V_cen 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.

Key Words: Valve repair • Computer modelling • Mitral regurgitation • Echo-Doppler

	Introduction

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The edge-to-edge technique is an alternative method of valve repair that has been applied to treat mitral [1], as well as tricuspid [2] regurgitation. According to this procedure, valve competence is restored by suturing the free edges of the leaflets, either at the middle portion (creating a double orifice valve) or at the commissure (commissural obliteration), depending on the mechanism of the regurgitation and on the site of valvular lesions. The technique has been effectively used to treat mitral regurgitation due to complex mechanisms such as post-endocarditic, ischemic valve insufficiency, Barlow disease and regurgitation associated to dilated cardiomyopathy [3].

The drawback of the technique is that the edge-to-edge suture, significantly, reduces the effective orifice area. The valve area reduction is more considerable when a double orifice valve is created as in the case of the treatment of Barlow disease or mitral repair for dilated cardiomyopathy.

A computational model of a double-orifice mitral valve based on the Finite Elements Method (FEM) [4] was used to assess the hemodynamic effects of the repair. Computational analysis has been successfully applied in cardiovascular research to investigate on surgical and diagnostic procedures and is a valuable alternative to in vitro studies [5] [6] [7].

The model was developed to address three main issues arising from clinical experience: (1) is the hemodynamic performance of the mitral valve affected by the configuration of the orifice (single vs. double orifice)? (2) Does the design of the double orifice valve influence the hemodynamics (orifices of equal versus unequal areas)? (3) How Doppler-derived flow velocity analysis should be used to determine pressure gradients through the valve under the conditions of a double orifice flow pattern?

	Methods

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A parametric 3D-computational model of the double-orifice mitral valve, based on FEM, has been constructed from clinical data obtained in patients undergoing double orifice correction. A left heart was simulated ( Fig. 1 ): the geometry of the atrium was cylindrical, with a radius of 24 mm and a height of 24 mm; the ventricle was a cone frustum whose base and apical radii were equal to 24 mm and 12 mm, respectively; its height was equal to 44 mm. The model of the valve reproduced the post-operative configuration with proper dimensions: the annular shape and dimensions were derived from the configuration of a nr 36 Carpentier ring (Baxter, Irvine, CA), since most of the procedures are associated with an annuloplasty to reduce and remodel the diseased annulus; the valvular plane was saddle shaped, convex towards the ventricle; either one or two orifices were assigned. Nine different geometries were investigated, corresponding to three total inflow areas (1.5, 2.25 and 3 cm²) 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).

View larger version (55K): [in this window] [in a new window]   Fig. 1. (a) 3D-reconstruction of the left heart, refer to the text for dimensional characteristics (b) meshed cross-section of the mitral valve with a single orifice configuration (c) meshed cross-section of the mitral valve with a double orifice configuration (orifices of equal areas, ratio 1:1) (d) meshed cross-section of the mitral valve with double orifice configuration (two orifices of different areas, ratio 1:2).

The simulations were performed in transit; the fluid was initially quiescent and was accelerated to the maximum flow rate with a cubic function. For all the geometries the maximum flow rate was set to 11 l/min. The influence of the flow rate (7, 11 and 15 l/min) on the hemodynamics was also assessed using a specific orifice configuration (two orifices with equal area and total area equal to 2.25 cm²).

For each case, some characteristic values of velocity and pressure were determined: namely, the overall maximum velocity in the jet flow downstream each orifice (V_max1, V_max2), the maximum velocity at the centre of the jet flow (V_cen1, V_cen2), and the maximum pressure drop across the valve(p_max). A further value of pressure drop was estimated on the basis of the velocity values by means of the simplified Bernoulli formula (4 V²) [4] [8] [9]. Pressure gradients calculated by means of the simplified Bernoulli formula (p_Bernoulli) were compared with the ones resulting from the simulation (p_max).

The full Navier Stokes equation and the continuity equation in their axis-symmetric formulation were solved using Galerkin's weighted residual approach in conjunction with finite element approximation [7]. A commercial code named FIDAP (Fluid Dynamic International, Evanston, IL) was used. Eight-node 3D-elements were used in the discretization for a total number of 73.000 elements in the case of two orifices and of 82.000 for the single orifice. The proper grid refinement was determined by comparing the behaviour of models with different number of elements. A segregated solver was employed for the solution method. The time integration technique adopted, was the implicit backward Euler with a fixed time step of 3 ms. The computations were carried out on a HP735 (Hewlett Packard Company, Paolo Alto, CA). The CPU time varied from 30 to 48 h for each simulation, depending on the orifice number and shape.

	Results

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The fluid dynamics occurring in the investigated area is illustrated on the colour mapped plots of the velocities ( Fig. 2 ) and pressures ( Fig. 3 ) obtained for the cases with a total area equal to 2.25 cm² (simulations 4, 5, and 6 of Table 1). Similar fluid dynamic features also occurred in the other simulations. The component of the velocity vector which is normal to the valvular plane was plotted instead of the speed value, since its colour map corresponds to the colour Doppler image, attainable when the ultrasonic beam is aligned to the valve outflow.

View larger version (62K): [in this window] [in a new window]   Fig. 2. Velocity colour map for simulations #4, #5 and #6 (total effective orifice area 2.25 cm2 (a) single orifice (b) double orifice with equal and (c) unequal areas).

View larger version (63K): [in this window] [in a new window]   Fig. 3. Pressure colour map for simulations #4, #5 and #6 (total effective orifice area 2.25 cm2 (a) single orifice (b) double orifice with equal and (c) unequal areas).

In the simulation of two orifices with different dimensions (5), the symmetry of the flow field is lost ( Fig. 2c), even if the velocities are not appreciably different through the two orifices (Table 1). In this case, for a total cross-area equal to 1.50 cm², the velocity jets, mapped with red colour, exhaust about after half ventricle. In general, their lengths depend on the maximum velocity and hence on the total cross sectional area, for a given flow rate value. Approximately, in the performed simulations, their lengths decrease by increasing the total cross-area and become about one fourth of the ventricle long axis when a total cross-area equal to 3.00 cm² is adopted.

In all the simulations, the velocity jets show a `horned' shape in the colour map cross sectional contour. This behaviour is a consequence of higher velocities reached by the fluid closer to the valve perimeter ( Fig. 4 ) at the valvular plane, due to the convective acceleration, i.e. to the momentum transferred to the fluid particles crossing the orifices by the fluid which in the atrium converges towards the orifices.

View larger version (21K): [in this window] [in a new window]   Fig. 4. Velocity profiles obtained at different distances along the long axis of the left heart in simulation #5.

Pressure drop evaluation using V_max in the simplified Bernoulli equation is well correlated with the p_max calculated by the simulations (y=0.9126x+0.3464, r=0.996); on the contrary the pressure drops estimated using V_cen underestimate (y=0.6757x+0.3073, r=0.999) the actual pressure drops (Table 1 and Fig. 5 ).

View larger version (24K): [in this window] [in a new window]   Fig. 5. Comparison between the actual pressure drops and the pressure drops calculated by means of simplified Bernoulli formula. Squares indicate the correlation with the maximum velocity; circles indicate the correlation with the maximum velocity at the centre of the jets.

View larger version (15K): [in this window] [in a new window]   Fig. 6. Influence of the total orifice area on the pressure gradients at 11 l/min. pmax, maximum pressure gradient across the valve; pBernoulli, pressure gradient calculated with the simplified Bernoulli formula (4Vmax2).

	Discussion

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The double orifice repair is a convenient method to treat mitral regurgitation due to complex mechanisms [1]. From 1993 through September 1998, we applied the technique on 122 patients: the indications for the double orifice repair were the prolapse of the anterior leaflet, alone or in combination with the posterior leaflet prolapse (as seen in Barlow disease), the prolapse of the posterior leaflet associated with severe annular calcification, the endocarditic lesions with erosion of the free edge of the leaflets impeding normal coaptation, the ischemic mitral regurgitation, and the repair of mitral regurgitation in combination with either the Batista procedure [3] or left ventricular aneurysmectomy (in both cases, mitral repair was carried out through the ventricle). Since the introduction of the technique, a progressively larger proportion of patients have been submitting to mitral repair at our Institution (in the most recent years the ratio between repair and replacement for pure mitral regurgitation approached 98%); not only the application of the technique widened the indications for valve repair, but the predictability of good results allowed early intervention in asymptomatic patients with mitral regurgitation due to complex lesions. The technique proved to be extremely simple and reproducible, as witnessed by short cross-clamp times and by the feasibility and the efficacy of the repair even in case of suboptimal exposure or non-completely understood mechanism of valve regurgitation (e.g. during aneurysm repair or in case of ischemic regurgitation) [1].

Although reliability and simplicity are the main advantages of the double orifice repair, considerable reduction of valve orifice area is the major drawback of the procedure. Valve area can be reduced by less than half of the preoperative one after the completion of the repair, and, for any given preoperative area, the pressure loss through the valve should be expected to be highest when the suture is placed exactly in the middle of the leaflets. In the latter case, the total effective orifice area resulting from the correction is smaller than when the suture is placed more laterally obtaining two orifices of different area.

Although effective orifice area reduction is usually not a significant problem, since the preoperative valve area is large in patients with chronic valve regurgitation, there are cases when preoperative orifice area of the mitral valve is not redundant (e.g. rheumatic disease can be associated with relatively smaller orifices and should be considered a relative contraindication for the `edge-to-edge' repair). Another matter of concern is the possible implication of a non-physiological mitral orifice configuration on the hemodynamics of the valve during ventricular filling.

The simulation of the fluid dynamics through single- and double-orifice mitral valves showed that the velocity of the blood – and hence the pressure gradients – is exclusively influenced by the total valve area (either as a single area or the sum of two areas) and it does not depend on the conformation of the orifices. In double-orifice valve configuration, the velocity of the flow through each orifice is very similar to the one observed through a single orifice valve of area equal to the sum of the areas of the two orifices ( Fig. 2a,b). Moreover, the velocities of the blood through the two orifices are very similar regardless the ratio between the areas of the two orifices ( Fig. 2b,c). This finding warrants the applicability of echo-Doppler examination for the assessment of the results of valve repair by means of non-invasive methods. During echo-Doppler examination, the flow through the valve can be probed at any of the two orifices, obtaining data on overall valve performance (flow velocity, pressure gradient, functional valve area).

Our preliminary clinical experience confirms these findings: in a series of ten patients, previously submitted to double orifice repair, in sinus rhythm, the velocities recorded at each orifice by Doppler examination did not differ by more than 5%. Moreover, according to the simulation results ( Fig. 4), the maximum velocity was recorded laterally with respect to the centre of the orifice. Simulations show that the lateral velocity can be considerably higher than the central one (Table 1 and Fig. 5); consequently, the underestimation of the pressure gradients was notably up to 35%, when the maximum velocity at the centre of the jets was considered for the pressure drop calculations. To the best of the author's knowledge, this occurrence has never been reported previously. This may be due to the fact that in normal valves the leaflets surround the jet, thus mitigating the lateral velocities.

The simulation showed that the pattern of pressure fields within the ventricle during diastolic flow is similar either with a single orifice or a double orifice valve. The only variation is in the subvalvar area, while the pattern in the atrium and in the middle zone and at the apex of the ventricle do not change. Moreover, the model showed an important pressure recovery within the ventricle (about 20%), downstream of the valvular plane, thus indicating that the kinetic energy of the jet is not completely dissipated. This was not influenced either by the configuration (single vs. double orifice) or by the shape (equal or different orifices) of the valve.

Hemodynamical assessment of transvalvular gradients from clinical cases was not available for comparison with simulation results. This is probably the main limitation of the study. Also, the model does not include the subvalvular apparatus in the design of the valve. From anatomical observations we know that in congenital double orifice valve, in its more common form, each orifice is related to one papillary muscle, in a way that the valve/subvalvular relationship is the same of that observed in parachute valves [10]. Whether this arrangement has hemodynamical consequences is unknown, although several cases of totally asymptomatic congenital double-orifice mitral valve have been reported. A redundant subvalvar apparatus may decrease the pressure recovery within the ventricle by generating vortexes. Another limitation are the simplified boundary conditions imposed to the lateral wall of the ventricle. In the present work a uniform enlargement of the ventricular wall was simulated. Truly, the motion of the ventricular wall is driven by the blood pressure. This phenomenon, known as fluid–structure interaction effect [11], typically occurs when a fluid is bounded by a deformable solid domain. In the present study, this effect was neglected since it is likely not to affect the fluid-dynamics of jets.

Clinical validation of these results is mandatory to confirm, in vivo, the following findings suggested by the simulations: the hemodynamic performance of a double-orifice mitral valve is the same of that of a single orifice one of equivalent effective orifice area; the ratio between the orifice areas does not influence the hemodynamics of the valve; Doppler-derived velocities are a good indicator of pressure loss through the valve. These findings support the reliability of the double orifice repair for the treatment of mitral regurgitation, and allow correct estimation of the results by non-invasive echo-Doppler examination.

	Footnotes

 
Presented at the 12th Annual Meeting of the European Association for Cardio-thoracic Surgery, Brussels, Belgium, September 20–23, 1998.

	Appendix A. Conference discussion

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Dr A. Arbulu (Detroit, MI): In your clinical cases do you use anticoagulants after surgery, and if you do, for how long?

Dr Maisano: We routinely give anticoagulants to patients submitted to mitral repair. In patients in sinus rhythm, we discontinue this therapy after 3 months, unless otherwise indicated. The same strategy applies for patients undergoing double orifice repair.

During the follow-up period, we recorded two thromboembolic events out of 122 patients submitted to the double-orifice mitral repair. Both patients were in atrial fibrillation. According to the computational model and to our clinical experience, the risk of thromboembolic events after double orifice repair is not higher than after other repair techniques.

Dr L. von Segesser (Lausanne, Switzerland): You have shown in a very elegant fashion that effective valve area is the key determinant for this repair of its gradients. Can you tell us how much area you lose from the single orifice transformed into the double orifice valve?

Dr Maisano: Double orifice technique is invariably associated with a reduction of the total orifice area of the mitral valve. The extent of this reduction depends on the position of the `edge-to-edge' stitch. The greatest reduction is observed when the stitch is exactly in the middle of the valve, in which case the valve has two symmetric orifices. In this case more than 60% area reduction should be expected after the repair. Area reduction is usually not a problem in patients with chronic mitral regurgitation, since preoperative area is wide, often higher than 10 cm². In our series, a mean area of 3.5 cm² has been observed postoperatively, without significant pressure drops. However, the risk of post-repair mitral stenosis should always be kept in mind during the operation, and the double orifice technique should be avoided in case of preoperative small mitral valve area.

Dr G. Rizzoli (Padua, Italy): I would like to know if the presence of atrial fibrillation has any relationship with the hemodynamics of your model?

Dr Maisano: Atrial fibrillation may influence the beat-to-beat stroke volume. Diastolic flow is not constant and there is the chance for higher pressure drops concomitantly with higher transvalvar velocities when the R–R interval is longer. However, this is a common finding, not specific for the hemodynamics of the double orifice repair.

Dr S. Hagl (Heidelberg, Germany): Can you say anything about left ventricular mechanics, especially about the filling characteristics of the left ventricle? These may be changed by abnormal diastolic function of the subvalvular apparatus resulting from restricted leaflet motion.

Dr Maisano: The present model was designed to assess the hemodynamics of the double orifice repair, unfortunately it cannot be used to answer your intriguing question. I agree with you that the subvalvular apparatus is remodelled after the repair; it becomes very similar to the apparatus of a congenital double orifice mitral valve. Each orifice has chordae attached to one papillary muscle in a way that has been described as a double parachute valve. Whether this configuration has any hemodynamic consequence is not known and should be addressed by further investigation. A hypothesis is that the remodeled subvalvar apparatus could cause a more turbulent flow, decreasing the intraventricular pressure recovery.

Dr N. DeVega (Malaga, Spain): Sorry to insist on the same point. When I do one of these Alfieri repairs, just after placing the stitches in the middle of the valve, the valve seems to me to be absolutely competent. I can't see the point in going and placing a ring. I would also like to ask you, what is the reason in placing a ring in a valve where the disease is in the leaflets, not in the annulus? What is the meaning of using a ring? I practically don't use any ring at all and sometimes I feel guilty because I see all my colleagues always using them, and I would like to know your opinion about that.

Dr Maisano: In our series of double orifice repair, an annuloplasty ring was implanted in most cases. There is a growing evidence that a ring is not always necessary to restore valve competence. One issue against the use of the ring is the hypothetical reduction of valve area. In our experience, the use of a ring did not significantly influence the post-operative area of the mitral valve after double orifice repair.

Dr L. Cohn (Boston, MA): Let me just take the prerogative and ask you one last question related to this question. Obviously at your institution you have had a lot of experience with this repair. Do you notice any difference in the long-term reoperation rate versus when you use a ring or no ring with this particular technique?

Dr Maisano: In our experience, the double orifice technique has been associated with ring annuloplasty in most patients. A ring annuloplasty was not performed in case of small preoperative valve area, especially at the beginning of the surgical series. More recently, ring annuloplasty is associated almost routinely with enhanced valve coaptation and to stabilize the repair. We now have 5-years follow-up, and during this period, three patients underwent reoperation for valve repair failure: all of them had an annuloplasty at first operation (in one case, the cause of reoperation was the partial detachment of the ring producing hemolysis). However, we could not identify the use of a ring as a risk factor for late reoperation. Further follow-up is probably needed to address this issue.

	References

Top Abstract Introduction Methods Results Discussion Appendix A. Conference... References

 

1. Maisano F., Torracca L., Oppizzi M., Stefano P.L., D'Addario G., La Canna G., Zogno M., Alfieri O. The edge-to-edge technique, a simplified method to correct mitral insufficiency. Eur J Cardio-thoracic Surg 1998;13:240-246.[Abstract/Free Full Text]
2. Maisano F., Lorusso R., Sandrelli L., Torracca L., Coletti G., La Canna G., Alfieri O. Valve repair for traumatic tricuspid regurgitation. Eur J Cardio-thorac Surg 1996;10:867-873.[Abstract]
3. McCarthy J.F., McCarthy P.M., Starling R.C., Smedira N.G., Scalia G.M., Wong J., Kasirajan V., Goormastic M., Young J.B. Partial left ventriculectomy and mitral valve repair for end-stage congestive heart failure. Eur J Cardio-thoracic Surg 1998;13:337-343.[Abstract/Free Full Text]
4. Fluid Dynamic International. FIDAP Theory manual. Evanston: FDI, 1993.
5. Ge S., Jones M., Shiota T., Yamada I., DeGroff C.G., Teien D.E., Baptista A.M., Sahn D.J. Quantification of mitral flow by Doppler color flow mapping. J Am Soc Echocardiogr 1996;9:700-709.[Medline]
6. de Leval M.R., Dubini G., Migliavacca F., Jalali H., Camporini G., Redington A., Pietrabissa R. Use of computational fluid dynamics in the design of surgical procedures: application to the study of competitive flows in cavo–pulmonary connections. J Thorac Cardiovasc Surg 1996;111:502-513.[Abstract/Free Full Text]
7. Pennati G., Redaelli A., Bellotti M., Ferrazzi E. Computational analysis of the ductus venosus fluid dynamics based on Doppler measurements. Ultrasound Med Biol 1996;22:1017-1029.[Medline]
8. Holen J., Aaslid R., Landmark K., Simonsen S. Determination of pressure gradients in mitral stenosis with a non-invasive ultrasound Doppler technique. Acta Med Scand 1976;199:455-460.[Medline]
9. Yoganathan A.P., Cape E.G., Sung H.-W., Williams F.P., Jimoh A. Review of hydrodynamic principles for the cardiologist: applications to the study of blood flow and jets by imaging techniques. J. Am Coll Cardiol 1988;12:1344-1353.[Abstract]
10. Bano-Rodrigo A., van Praagh S., Trowitzsch E., van Praagh R. Double orifice mitral valve: a study of 27 post-mortem cases with developmental, diagnostic and surgical considerations. Am J Cardiol 1988;61:152-160.[Medline]
11. Redaelli A., Montevecchi F.M. Computational evaluation of intraventricular pressure gradients based on a fluid-structure approach. J Biomech Eng 1996;118:529-537.[Medline]

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