The aortic interleaflet triangles annuloplasty: a multidisciplinary appraisal§

Andrea Mangini a,c,*, Massimo Giovanni Lemma a,c, Monica Soncini b,c, Emiliano Votta b,c,Monica Contino a,c, Riccardo Vismara b,c, Alberto Redaelli b,c, Carlo Antona a,c

aCardiovascular Surgery Department, ‘Luigi Sacco’ University General Hospital, Milano, Italyb Bioengineering Department, Politecnico di Milano, Milano, Italy

c ForCardio.Lab, Universita di Milano — Politecnico di Milano, Milano, Italy

Received 1 September 2010; received in revised form 2 December 2010; accepted 6 December 2010; Available online 11 February 2011

www.elsevier.com/locate/ejctsEuropean Journal of Cardio-thoracic Surgery 40 (2011) 851—857

Abstract

Objective: Aortic interleaflets triangles annuloplasty (AITA) reduces interleaflet triangles’ circumferential extent through properly placedsutures. To achieve aortic root functional unit (ARFU) stabilization, we aimed at quantifying the effect of suture extent (SE) on aortic valvefunction and at finding general optimization criteria.Methods: A previously published ARFU finite element model was modified to simulate ARFUdilation and AITA, systematically varying the SE and quantifying the corresponding regurgitant orifice (RO), leaflets co-aptation area (CA) andannular diameter (Da). Computational outcomes were tested by comparison with postoperative virtual basal ring echo data of 105 successfullycorrected ARFUs. Results: According to our finite element simulations of AITA, RA and CA depended linearly on SE, through a relationship thatpredicted optimal surgical results when SE was equal to 48% of the interleaflet triangle height (ITH). Follow-up data showed that, after AITA, ARFUdiameter decreased from 23.4 � 3.93 to 20.1 � 1.8 mm, ( p < 0.05) at the annulus, from 41.53 � 6.347 to 38.2 � 4.0 mm, (p < 0.01) at thesinuses, and from 41.3 � 6.47 to 35.25 � 5.95 mm ( p = ns) at the sinotubular junction (STJ). Themean ITH was 11.18 � 1.74 mm and themean SEpredicted by our model was 5.34 � 0.6 mm, that is, 47.76% of the ITH, comparable to 48% of the computational model. Leaflet co-aptation length(CL) increased from 2.73 � 1.25 to 7.56 � 2.36 mm (p < 0.001), while the CA evaluated via finite element modeling changed from 8% to 48%.Conclusions: So far, the AITA seems to be a valuable technique to increase leaflet CL in aortic valve repair and in silicomodels seem to be able topredict the principles of the phenomena but not the individual complexity.# 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

Keywords: Aortic valve repair; Aortic valve finite element models; Computational cardiac surgery; Aortic annuloplasty; Interleaflet triangles

1. Introduction

Aortic interleaflets triangles annuloplasty (AITA), firstdescribed by Cabrol et al. in 1969 [1], was a simple techniqueto achieve aortic root functional unit (ARFU) stabilizationafter aortic valve leaflet repair, improving leaflet co-aptation and functional valve reserve. For the parabolicshape of the interleaflet triangles (ITs) edges, the AITA wasempirically performed at 50% of the IT height (ITH).However, the relationship between the height of the AITAand the clinical result in terms of virtual basal ring (VBR) [2]reduction, co-aptation area (CA), and regurgitant area (RA)are not known. Moreover, there are only a few data availableabout IT anatomy.

§ Presented at the 24th Annual Meeting of the European Association forCardio-thoracic Surgery, Geneva, Switzerland, September 11—15, 2010.* Corresponding author. Address: Cardiovascular Surgery Department, ‘Luigi

Sacco’ University General Hospital, Via G.B. Grassi 74, ZIP Code 20157, Milan,Italy. Tel.: +39 02 39042333; fax: +39 02 39042652.

E-mail address: mangini.andrea@hsacco.it (A. Mangini).

1010-7940/$ — see front matter # 2010 European Association for Cardio-Thoracicdoi:10.1016/j.ejcts.2010.12.038

The aim of this study was to identify the optimalheight to perform AITA using a multidisciplinary approachbased on finite element modeling of the AR, post-mortem investigation of the IT anatomy, and analysis ofechocardiographic data of several aortic valve repairprocedures.

2. Methods

The study protocol encompassed a multidisciplinaryapproach based on three different investigational areas:

(1) B

Surge

ioengineeristic area: Development of AITA finite ele-ment modeling to simulate different procedures and tofind out the mathematical relationship between AITAheight and VBR diameter, CA and RA;

(2) A

natomical area: To investigate the peculiar anatomicalfeatures of the three ITs and the differences amongthem; and

(3) C

linical area: To compare postoperative echocardio-graphic data of our surgical aortic valve repair population

ry. Published by Elsevier B.V. All rights reserved.

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857852[()TD$FIG]

Tablemode

Geomfeatu

dahad1h1dmhmd2h2dSTJhSTJlrlclfmlimIT he

da, arelatand iwidthlengtleafle

with the information provided by the bioengineeristicand anatomical areas.

2.1. Bioengineeristic area

(a) Physiological finite element modeling

Fig. 1. Physiological (a) and pathological (b) ARFU models. Top panel: aorticwall including ITs (orange), VSs (green) and AA (red). Bottom panel: detail ofthe aortic valve ITs (orange) and VLs (blue).

Geometry — The basis for the computational activitywas previously published in an article by our researchgroup; [3] hence, its main features are here brieflydescribed. The model assumes three-leaflet symmetryand includes all of the ARFU sub-structures: ITs, valvularleaflets (VLs), valsalva sinuses (VSs) and the proximaltract of the ascending aorta (AA). The initial unloadedconfiguration of the system was assumed correspondingto the open valve one, with 80 mmHg pressure in theventricle and in the AA and, thus, 0 mmHg transvalvularpressure drop.

ITs and VSs geometry was based on echocardiographicdata from 112 healthy subjects. VL configuration was setaccording to the Thubrikar [4] method, using an annulusdiameter equal to 24 mm, with the aim to make themodeled ARFU configuration comparable to the oneadopted in other studies from literature [5]. The AAproximal segment was assumed cylindrical, 11 mm long,and with a diameter equal to the diameter of thesinotubular junction (STJ). The main dimensions of themodel are synthesized in Table 1. The whole physiologi-cal root model was discretized with 32 722 4-node shellelements with reduced integration (Fig. 1(a)). Shellthickness was set to 2.13, 1.64, 0.71, and 2.30 mm forAA, VSs, VLs, and ITs, respectively, on the basis ofliterature data [6].

Tissues mechanical response — All tissues wereassumed as linear, elastic, isotropic materials; the YoungModulus was assumed equal to 1 MPa for VLs and ITs and2 MPa for VSs and the AA [5]. A 0.45 Poisson ratio wasassumed for all tissues [7]. The density was set to

1. Main dimensions used to build the physiological and the pathologicalls.

etricalre

Physiological model [mm] Pathological model [mm]

24.00 31.201.00 1.00

35.52 36.056.00 6.00

39.12 39.1212.24 12.2438.64 38.6418.00 18.0030.24 30.2424.00 24.0016.80 16.808.52 8.52

36.57 36.5731.10 35.58

ight 8.48 6.30

nnulus diameter, ha, annulus height; dm and hm, maximum width anded distance from the annular plane of the VSs; dSTJ and hSTJ, STJ diameterts position with respect to the annular plane; d1 and d2, two intermediates; h1 and h2, corresponding intermediate positions; lr, leaflet radialh; lc, leaflet commissural length; lfm, leaflet free margin length; lim,t insertion margin length; IT, interleaflet triangles.

1.1�10�04 kg mm�3 for the aortic valve and2�10�04 kg mm�3 for the AA, that is, two orders ofmagnitude higher than the corresponding real values, toaccount for blood inertia effects [3,5,8,9].

Boundary conditions and contact interactions — ARFUfunction was simulated during the entire cardiac cycle.The nodes of the aortic annulus were constrained withrespect to translations, while radial expansion orcontraction of the distal end of the AA was allowed.Blood pressure acting on root structures was modeledusing time-dependent pressure loads; a physiologicaltransvalvular pressure drop ranging from 0 to 107 mmHgwas applied to VLs, while a relative aortic pressureranging from 0 to 40 mmHg was applied to VSs and theAA. VL co-aptation and interactions between VLs and thesurrounding structures were modeled assuming a 0.05friction coefficient.

Simulations were run using the commercial solverABAQUS/Explicit 6.4-1 (Simulia, Dessault Systemes).

(b) P

athological finite element modeling

The model of dilated ARFU with aortic insufficiencydiffered from the physiological model only by itsgeometrical features. These were defined accordinglywith criteria identified by expert cardiac surgeons: theannulus diameter was increased to 31.2 mm and the VSswere dilated until their maximumdiameterwas increasedby 30%. VLs’ insertion line extent and VLs’ surface wereincreased by 15% and ITH was decreased from 8.5 to6.3 mm. The main dimensions of the model are shown inTable 1. The corresponding geometricalmodel, whichwasdiscretized into 33 696 four-node shell elements withreduced integration, is depicted in Fig. 1(b).

(c) A

ITA model

The AITA model was obtained through two steps. Inthe first step, the suturing of ITs was simulated on the

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857 853[()TD$FIG]

Fig. 2. Steps followed to simulate AITA. (a) Initial pathological geometry. (b)Detail of the zenith of an IT: the vertical dashed black line and the horizontalcontinuous one represent, respectively, the ITsymmetry plane and the thresh-old SE. Blue dots indicate nodes displaced radially inward by 1 mm, red dotsindicate nodes being moved onto the symmetry plane and black arrowsexemplify the imposed displacement for one couple of nodes. (c) Unpressur-ized geometry with simulating stitches. (d) smoothed geometry after theapplication of a 26 mmHg inner pressure to VSs.

[()TD$FIG]

Fig. 3. Example of anatomical measurement of the IT.

unloaded pathological model, as schematized in Fig. 2.The nodes on the symmetry plane of each ITwere movedradially inward by 1 mm, and the nodes located on thejunction between the VSs and ITs, within a thresholddistance (AITA level = H) from the zenith of the ITs in thelong-axis direction, were symmetrically displaced ontothe IT’s symmetry plane, so as to coincide two by two.Subsequently, coincident nodes were tied together viakinematic constraints to simulate the presence of thestitch. To test the effects of different locations of thesimulated stitches, three different values of H wereconsidered in three different AITA models: 1.8, 2.4, and3.0 mm. In the second step, the VSs’ profile, which wasaffected by the manipulations just described, wassmoothed by applying a 26 mmHg pressure on VSs innersurface, while preventing the annulus and the AA distalend from translating. The final configuration of thecorrected ARFU was exported and re-imported inABAQUS/Explicit to simulate ARFU function during thecardiac cycle. For this purpose, the same boundaryconditions described for the physiological model wereapplied.

2.2. Anatomical area

We studied 16 formol-fixed human hearts with normalaortic roots to specifically review the morphological featuresof the ITs together with their mode of connection to theadjacent structures. Mean cadaver age was 74 � 16 years(range 26—93 years), all Caucasian; nine were female. Thespecimens were prepared for measurements by trimming theAA 1 cm above the STJ, and circumferentially dissecting theleft ventricular outflow tract 1 cm below the nadir of the VSs.Specimen analysis was made after opening the ARFUlongitudinally through the middle portion of the non-coronary VSs, to keep the ITs intact and spreading the

opened ARFU on a flat surface without stretching it. Thespecimens were than photographed using a 6.1-megapixeldigital camera (Nikon D70) at a standard distance of 30 cm,both with the leaflets in place and after removing them.Pictures were subsequently reviewed using a computer-aideddesign software (Auto CADW, Autodesk, 2004) for indirectstructures’ measurements. A centimeter ruler was placedunder each specimen and included in the pictures allowed forsoftware calibration and image sizing. A 10-fold magnifica-tion was used to precisely contour the different ARFU parts tobe analyzed and to measure the ITs’ relationship (Fig. 3).

2.3. Clinical area

Between September 2003 and February 2008, we enrolleda total of 105 patients with a diagnosis of aortic valveregurgitation. The mean age was 59.5 � 15.2 years; 67patients were male and 38 female. All subjects werediagnosed based on echocardiography criteria and scheduledfor aortic valve surgical repair after signing an informativepaper on the planned repair procedures and their resultsfrom literature. Patients were excluded, if affected by valvestenosis with complete fusion and calcification of the threeleaflets, regardless of the ventriculo-aortic gradient (D) andif affected by a bicuspid aortic valve. None of the patientshad co-morbidities that could influence the modalitiesadopted for AITA, nor VSs’ dilation requiring a sparingprocedure. Coronary catheterization was performed inpatients aged > 45 years or in the presence of significantsurgical risk factors. Preoperative transthoracic echocardio-graphy (TTE) was performed to assess aortic valve pathology,left ventricular function, and to rule out the presence ofassociated mitral or tricuspid disease. The degree of valvularregurgitation was evaluated as grade 0 to IV. Beforecardiopulmonary bypass, transesophageal echocardiography(TEE) was performed to assess the mechanism of regurgita-tion according to the El Khoury Classification [10], and tomeasure the ARFU features as described by Anderson [2,11]:VBR, aortic root, STJ and AA.

The chest was opened through a median sternotomyincision and the patient was placed on cardiopulmonary

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857854

Table 2. Percentage of aortic valve repair techniques associated to AITA.

Concomitant surgical technique Percentage of patients (%)

Ascending aorta replacement 67.6Shaving 35.2Free margins reinforcement 27.6Leaflet plicature 11.4Free margins remodelling 10.5STJ plicature 9.5Triangular resection 2.9Leaflet patch 1.9

Table 3. Computational outcomes defining aortic valve competence: regur-gitant area (RA), leaflets coaptation area (CA), annular diameter (Da), aorticinterleaflets triangles annuloplasty (AITA), suture extent (SE).

Model RA [%] CA [%] Da [mm]

Physiological 0 45 24.0Pathological 10 0 31.2AITA SE 1.8 mm 9 8 29.6

SE 2.4 mm 5 32 28.0SE 3.0 mm 0 48 26.4

bypass with cannulation of the AA and of the right atriumappendage or, if a mitral or tricuspidal repair was necessary,of both venae cavae. After induction of cardiac arrest byinfusion of cold crystalloid cardioplegia (St. Thomas Solu-tionW) into the coronary ostia, the aortic valve and root wereinspected to add ‘surgical-oriented’ information to TEEanalysis, and the ARFU repaired by the association ofdifferent surgical techniques (Table 2).

[()TD$FIG]

3. Data analysis

The statistical analysis of data was performed usingStatistical Package for Social Sciences (SPSSW) 13.0 software(SPSS Inc., Chicago, IL, USA). Normal distribution was testedusing both the Kolmogorov—Smirnov statistics with aLilliefor’s significance level and the Shapiro—Wilk test.Continuous data are presented as means � standard devia-tions. The Student’s Paired t-test was used after evidence ofnormality. Nominal data are presented as absolute frequen-cies or percentages. Analysis of categorical variables wasperformed by the x2 test or Fisher’s exact test whereappropriate. A two-tailed p value < 0.05 was consideredstatistically significant.

Fig. 4. Interpolation of CA, RA and Da data obtained for the three simulatedAITA configurations showing their linear dependency on the suture extent SE.

4. Results

4.1. Bioengineeristic area

Given the purpose of the present study, the analysis ofcomputational data focused on leaflet CA, on aortic valveRA and on the annular diameter (Da in the finite elementmodel and VBR in surgical terminology) corresponding tothe three simulated AITA configurations. All of thementioned parameters were assessed at maximal diastolictransvalvular pressure drop. CA was quantified as thefraction of leaflet surface characterized by a non-zerocontact pressure, and RA was estimated as the fraction ofvalvular orifice area not occluded by VLs in a short-axisview. The values of the mentioned parameters are reportedin Table 3 for the physiological, pathological, and AITAmodels. According to AITA simulations, all of themdepended linearly on H in the considered range ofconfigurations (Fig. 4). The AITA repair simulation with Hequal to 3 mm seemed to be the optimal correction toperform; in this simulated postoperative configuration,valve competence was restored (RA = 0%). CA and Da valueswere very similar to the ones estimated for the physiolo-gical model. The CA value increased up to 48%.

4.2. Anatomical area

The mean ITH measured on the three ITs of 16 humanhearts was 11.1 � 1.7 mm (range 6.1—14.7 mm). The meanapex angle was 48 � 128 (range 28—628).

4.3. Clinical area

No patient underwent emergency surgery. One patientdied within 30 days from the procedure (operative mortality:0.95%) due to aortic wall rupture.

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857 855

After the repair procedure, there was an increase of co-aptation length (from 2.7 � 1.2 to 7.6 � 2.4 mm (significantp = 0.01) and a decrease of the diameters of the VBR (from23.4 � 3.9 to 20.1 � 1.8 mm (significant: p = 0.03) of theaortic root (from 41.5 � 6.3 to 38.2 � 4.0 mm (significant:p = 0.0003) and of the STJ (from 41.3 � 6.5 to 35.2 � 5.9 mm(significant: p = 0.003). Aortic regurgitation echocardio-graphic grade � II was found preoperatively in 102 patientsand at discharge in three patients (significant x2 = 181.9,p = 0.001). The mean and maximum ventriculo-aorticgradient did not change significantly (Dmax from19.5 � 10.2 mmHg to 21.8 � 11.7 mmHg, ns: p = 0.13; Dmean

from 11.8 � 7.4 mmHg to 12.8 � 6.9 mmHg, ns: p = 0.31).The left ventricular end-diastolic volume decreased from143 � 56.9 ml to 132.3 � 55.8 ml (ns: p = 0.06) and the leftventricular end-diastolic diameter changed from 56.1 �7.7 mm to 52.4 � 8.6 mm (ns: p = 0.12). During a follow-up of7 years, two patients were re-operated for aortic regurgita-tion grade > 2.

[()TD$FIG]

Fig. 5. ITschematic representation: a—b and a0—b0 could be considered almostparallel; b—c and b0—c0 are divergent.

5. Data synopsis

The in silicomodel returned a linear relation between theVBR diameter and the AITA level in terms of height:

VBRðdiameterÞ ¼ �2:68 � AITA levelþ 34:43

Resolving the equation for the AITA level, we obtained:

AITA level ¼ 34:43� VBRðdiameterÞ2:68

Our follow-up data included the postoperative VBR(diameter) of each patient measured by long-axis intra-operative TEE view. Thus, we could use this equation tocalculate the estimate height (eHi) of the stitch for eachpatient:

eHi ¼34:43� Postoperative VBRi

2:68; i ¼ 1; . . . ; 105

We then estimated the corresponding mean value andstandard deviation for our AITA procedures, thus obtainingeH = 5.34 � 0.6 mm.

The anatomical study reported a medium ITH of11.18 � 1.74 mm; our eH mean value represented 47.76%of the ITH mean value:

eH% ¼ eH

ITH¼ 5:34

11:18� 100 ¼ 47:76%

6. Discussion

The AITA was first introduced by Cabrol et al. in 1966(Cabrol stitch) [1] to repair the aortic valve in presence ofaortic valve regurgitation due to VBR dilatation. Histechnique consisted in a U suture reinforced by two Teflonpledgets in the apex of the IT to correct the STJ dilatationand at a non-defined height toward the left ventricle tocorrect what he called ‘the inferior aortic diameter’(currently VBR). The issue of non-defining a height or aneasy procedure to calculate an adequate height where to

perform the AITA led this technique to a non-standardization.El Khoury et al. [10] redefined these ideas with the concept ofthe functional aortic annulus (STJ + VBR) as the natural stentof the aortic valve responsible for inducing regurgitationwhen dilated, and described the importance of AITA withoutdefining an adequate height value. Fraser and Cosgrove [12]in 1994 underlined the importance of providing improvedsupport for the cusp after valve closure, increasing with thistechnique the area of leaflet co-aptation, called lunula. Thispart that in the model we call CA seems to be dependent onthe level at which the sutures are placed in the ITs. Moreover,the authors cautioned about avoiding an excessive AITA depthleading to potential valve stenosis without explaining how tocalibrate the surgical maneuver or the mechanism involved.In our experience, AITA has been used both to reduce the VBRand to stabilize the surgical repair in the long-term,borrowing the idea from mitral valve repair. We startedempirically performing AITA at 50% of the ITH. Themotivationof this choice is that, from an anatomical standpoint, the IT isnot a triangle but a structure formed by two rounded sides ofparabolic shape and a curve line connecting the nadir of thetwo adjacent cusps. In their upper half, from the STJ to 50%of the ITH, the two sides are almost parallel, and, in theirlower half, they start to diverge to reach the nadir of thecorrespondent cusp (Fig. 5). Closing the upper part with apledget-reinforced braided suture would increase the CAwithout significantly impinging leaflet motion or leftventricle-aortic root pressure drop, while going after thislandmark would alter the valve cinematic generatingpressure drop and stresses. On this basis, we built ourcomputational model to identify the best AITA height in termsof RA minimization, CA and VBR diameter size restoration.According to our numerical results, the optimal AITA sutureheight corresponds to 48% of ITH; in this configuration, CAwas increased nearly up to its physiological extent (48% vs45% physiological value), valve continence and normal VBRdiameter were restored (RA = 0%, VBR diameter = 26.4 mm vs24 mm physiological value). In preliminary in vitro analysescarried out in an ad hoc pulsatile mock loop, whose detaileddescription is beyond the goals of the present study, we

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857856

observed that an over-reduction of VBR diameter allows co-aptation of the lower part of the lunula, but induces theopening of its upper part, as in a funnel-like configuration.This configuration is of course non-physiologic and is likely tobe suboptimal from a functional standpoint. This experi-mental evidence, although preliminary, supports our con-clusions based on numerical results.

The knowledge of the human ITs anatomy and ourmeasures by the anatomical area allowed us to define asnormal an ITwith an apex angle < 608 and amedium height of10.7 � 1. 8 mm. To best standardize these measures, wepreferred to calculate mean values and standard deviationfor the complete series of 48 triangles, without grouping foranatomical position.

Using the three linear regression formulas, obtainedfrom finite elements, which expressed CA, RA, and VBR asa function of AITA suture height, we confirmed both theadequacy of the suture height we previously adopted inour surgical practice due to an empirical criterion, and themodel capability to explain the main relationships inthe aortic root functional unit corrected by an AITAprocedure. The starting hypothesis of performing theAITA at 50% of ITH was confirmed by the result of theestimated height eH% (47.7%) and the identification bythe model of the 48% as the best place where to performthe AITA.

We confirm from our experience the feasibility of the AITAprocedure in association with all the other aortic valve repairtechniques both to reduce the VBR and to stabilize the resultobtained. No Kaplan—Meier analysis was performed on thisgroup of patients, representing a part of the aortic valverepair patients treated in our hospital, identified to matchthe computational studies. The possibility of performingasymmetric AITAs depending on the insertion of the leafletson the commissures, to restore a symmetric lunula, couldexpand the use of this technique where the use of an externalor internal complete ring appears to be not adequate.Moreover, the observation by Dagum et al. [13] concerningthe importance of maintaining annular and commissureflexibility as a key component that allows the aortic root todissipate cuspal stress during valve closure associate to thefinding of an asymmetric torsional component of aortic rootdeformation, underline the importance of AITA. The AITA, infact, increases co-aptation leaving the VBR free to movefollowing the root dynamics, due to the ‘inverted Yconfiguration’ obtained. The left aortic region (the areaunder the non coronary left commissure) underwent thegreatest amount of circumferential and torsional deforma-tion, while the non coronary-right root region deformed theleast. This mechanism may minimize opening shear stresseson the valve cusps near their insertion along the commis-sures, decoupling the asymmetric torsional deformations ofthe annulus to the STJ symmetric ones [13].

So far, the AITA seems to be a valuable technique toincrease leaflet co-aptation length in aortic valve repair andin silico models seem to be able to predict the principles ofthe phenomena but not the individual complexity.

In conclusion, AITA stitch positioning at 50% of ITH allowsoptimal leaflet co-aptation and RA reduction, withoutimpinging blood flow through the VBR. These features makeit ideal not only to correct aortic valve regurgitation but also

to stabilize aortic valve repair procedures, preventing futureVBR dilation.

References

[1] Cabrol C, Cabrol A, Guiraudon G, Bertrand M. Le traitement de l’insuffi-sance aortique par l’annuloplastie aortique. Arch Mal Coeur Vaiss1966;59: 1305—12.

[2] Anderson RH. The surgical Anatomy of the aortic root. Multimed ManCardiothorac Surg, doi:10.1510/mmcts.2006.002527.

[3] Soncini M, Votta E, Zinicchino S, Burrone V, Mangini A, Lemma M, AntonaC, Redaelli A. Aortic root perfomance after valve sparing procedure: acomparative finite element analysis. Med Eng Phys 2009;31:234—43.

[4] Thubrikar M. The aortic valve. Boca Raton: CRC Press; 1990.[5] Gnyaneshwar R, Kumar RK, Balakrishnan K. Dynamic analysis of the aortic

valve using a finite element model. Ann Thorac Surg 2002;73:1122—9.[6] Grande-Allen KJ, Cochran RP, Reinhall PG, Kunzelman KS. Stress varia-

tions in the human aortic root and valve: the role of anatomic asymmetry.Ann Biomed Eng 1998;26:534—45.

[7] Sripathi VC, Tech B, Kumar KR, Balakrishnan RK. Further insights intonormal aortic valve function: role of a compliant aortic root on leafletopening and valve orifice area. Ann Thorac Surg 2004;77:844—51.

[8] Sutton III JP, Ho SY, Anderson RH. The forgotten interleaflet triangles: areview of the surgical anatomy of the aortic valve. Ann Thorac Surg1995;59:419—27.

[9] Hose DR, Narracott AJ, Penrose JM, Baguley D, Jones IP, Lawford PV.Fundamental mechanics of aortic heart valve closure. J Biomech2006;39:958—67.

[10] El Khoury G, Glineur D, Rubay J, Verhelst R, D’Udekem d’Acoz Y, PonceletA, Astarci P, Noirhomme Ph, Van Dyck M. Functional classification of aorticroot/valve abnormalities and their correlation with etiologies and surgi-cal procedures. Curr Opin Cardiol 2005;20:115—21.

[11] Anderson RH. Clinical anatomy of the aortic root. Heart 2000;84:670—3.[12] Fraser CD, Cosgrove DM. Surgical techniques for aortic valvuloplasty.

Texas Heart Inst J 1994;21:305—9.[13] Dagum P, Green RG, Nistal FJ, Daughters GT, Timek TA, Foppiano LE,

Bolger AF, Ingels NB, Miller DC. Deformation dynamics of the aortic root —modes and physiologic determinants. Circulation 1999;100:II54—62.

Appendix A. Conference discussion

de Dr H-J. Schafers (Homburg/Saar, Germany): My feeling is that theheight at which we place such a plication suture should depend on the degreeof annular enlargement. So do you suggest 50% in everybody, or would youmake specific recommendations regarding the height of subcommissuralplication depending on the degree of aorto-ventricular dilatation?

Dr Mangini: Absolutely. We have to consider stabilization or repair of thefunctional unit. If we perform an aortic valve repair procedure in which wewant to stabilize the functional unit, we have to put the stitch at 50% of thesubcommissural triangle. If we also have a pathology of the ventricular-aorticjunction, we strongly believe that could be a powerful tool for the possibility oftailoring this height in the three triangles in order to obtain the best result. Soif you have a ventriculo-aortic junction huge dilatation, with an apex angle ofmore than 60 degrees, we can bemore aggressive going down with the stitch toachieve more closure of the triangle. Otherwise, 50% of the interleaflettriangles height is a good option.

Dr Schafers: If you do the plication at the 50% level, you reduce thecircumference of the root by a total of maybe 6 or 7 mm. What is the sizereduction effect on the basal ring?

Dr Mangini: We have shown this in our data.

Dr Schafers: I missed it; it went by so quickly.

Dr Mangini: Sorry. We discovered a linear relationship between the aorticinterleaflets triangles annuloplasty height and the ventricular-aortic junctiondiameters. In clinical practice this means a reduction in terms of diameter ofabout 5 mm.

Dr A. Takriti (Damascus, Syria): Is it necessary to do the Cabrol stitch in thethree commissures if you have asymmetrical leaflet cusps? If you have onesmall cusp, do you do the three stitches?

Dr Mangini: Yes, I always perform it on the three triangles, never on onlyone, because you can completely change all the dynamics of the aortic root. Istrongly believe you don’t work on leaflets but on the aortic root functional

A. Mangini et al. / European Journal of Cardio-thoracic Surgery 40 (2011) 851—857 857

unit. If the leaflet is small and the triangle is small, this could stabilize yourlong-term results.

Dr El Khoury (Bruxelles, Belgium): Andrea, from your model I understandthat doing the subcommissural annuloplasty at 50% of the height maybe canimprove the coaptation, but I can’t see very well how it can stabilize thehorizontal plane or whatever of the aorto-ventricular junction.

Dr Mangini: The virtual basal ring?

Dr El Khoury: I understand that 50% maybe is very good at the level of theright main or the left-right, but between the main and left maybe we have to

go even, we have to go deeper anyway, because we want to stabilize the repairby improving the coaptation but also by reducing and really stabilizing theaorto-ventricular junction.

DrMangini: At 50% you already reduce the annulus. The problem is, and weclearly demonstrate it by our mock loop simulation, that going down the 50%you start to dramatically increase the pressure drop.We don’t want, of course,to create a valve stenosis by hampering the leaflet motion. The aorticinterleaflets triangles annuloplasty performed at 50%, produces a virtual basalring reduction without hampering their motion.