Three-dimensional geometric comparison of partial and complete flexible mitral annuloplasty rings

The impact of annuloplasty ring or band implantation on post-repair mitral valve haemodynamic performance

OBJECTIVES

The clinical importance of optimal post-repair mitral valve diastolic performance is increasingly being recognized. The haemodynamic effect of a partial annuloplasty band implantation, in comparison to a full ring, remains insufficiently explored.

METHODS

Patients undergoing mitral valve repair for pure degenerative disease between 2011 and 2019 at 2 experienced heart valve centres were eligible for inclusion. Exclusion criteria were concomitant procedures other than tricuspid valve repair and ablation procedures for atrial fibrillation. Pre-discharge and follow-up echocardiograms (1-4 years after surgery) were analysed to assess haemodynamic mitral valve performance.

RESULTS

Of 535 patients meeting the inclusion criteria, 364 (68.0%) patients underwent full annuloplasty ring and 171 (31.0%) partial band implantation. On predischarge echocardiogram, post-repair mitral valve gradient and area did not differ between groups [2.89 mmHg (IQR 2.26-3.72) vs 2.60 mmHg (IQR 1.91-3.55), P = 0.19 and 1.98 cm2 (IQR 1.66-2.46) vs 2.03 cm2 (IQR 1.55-3.06), P = 0.15]. However, multivariable linear regression analysis demonstrated band annuloplasty as a determinant of larger valve area (coefficient 0.467 cm2, standard error 0.105, P < 0.001). On multivariable analysis, no significant impact on post-repair gradient was observed (-0.370 mmHg, standard error 0.167, P = 0.36). At follow-up, the differences between groups disappeared and multivariable regression analysis failed to demonstrate a significant impact of annuloplasty device type on mitral valve gradient (coefficient -0.095 mmHg, standard error 0.171, P = 1.00) or area (coefficient -0.085 cm2, standard error 0.120, P = 1.00). These results were confirmed with a linear mixed model analysis.

CONCLUSIONS

Partial band annuloplasty was related to an improved haemodynamic profile directly after valve repair for degenerative disease but the effect was short-lived. Our results suggest that the type of annuloplasty device has no durable impact on diastolic valve performance.

DynaRing: A Patient-Specific Mitral Annuloplasty Ring With Selective Stiffness Segments

Annuloplasty ring choice and design are critical to the long-term efficacy of mitral valve (MV) repair. DynaRing is a selectively compliant annuloplasty ring composed of varying stiffness elastomer segments, a shape-set nitinol core, and a cross diameter filament. The ring provides sufficient stiffness to stabilize a diseased annulus while allowing physiological annular dynamics. Moreover, adjusting elastomer properties provides a mechanism for effectively tuning key MV metrics to specific patients. We evaluate the ring embedded in porcine valves with an ex-vivo left heart simulator and perform a 150 million cycle fatigue test via a custom oscillatory system. We present a patient-specific design approach for determining ring parameters using a finite element model optimization and patient MRI data. Ex-vivo experiment results demonstrate that motion of DynaRing closely matches literature values for healthy annuli. Findings from the patient-specific optimization establish DynaRing's ability to adjust the anterior-posterior and intercommissural diameters and saddle height by up to 8.8%, 5.6%, 19.8%, respectively, and match a wide range of patient data.

A toolbox for generating scalable mitral valve morphometric models

The mitral valve is a complex anatomical structure, whose shape is key to several traits of its function and disease, being crucial for the success of surgical repair and implantation of medical devices. The aim of this study was to develop a parametric, scalable, and clinically useful model of the mitral valve, enabling the biomechanical evaluation of mitral repair techniques through finite element simulations. MATLAB was used to parameterize the valve: the annular boundary was sampled from a porcine mitral valve mesh model and landmark points and relevant boundaries were selected for the parameterization of leaflets using polynomial fitting. Several geometric parameters describing the annulus, leaflet shape and papillary muscle position were implemented and used to scale the model according to patient dimensions. The developed model, available as a toolbox, allows for the generation of a population of models using patient-specific dimensions obtained from medical imaging or averaged dimensions evaluated from empirical equations based on the Golden Proportion. The average model developed using this framework accurately represents mitral valve shapes, associated with relative errors reaching less than 10% for annular and leaflet length dimensions, and less than 24% in comparison with clinical data. Moreover, model generation takes less than 5 min of computing time, and the toolbox can account for individual morphological variations and be employed to evaluate mitral valve biomechanics; following further development and validation, it will aid clinicians when choosing the best patient-specific clinical intervention and improve the design process of new medical devices.

Tricuspid Annuloplasty Rings: A Quantitative Comparison of Size, Nonplanar Shape, and Stiffness

BACKGROUND

Functional tricuspid regurgitation due to annular and ventricular dilatation is increasingly recognized as a significant source of morbidity and mortality. To repair the annulus, surgeons implant one of many annuloplasty devices that differ in size, 3-dimensional (3D) shape, and stiffness. However, there have been no quantitative comparisons between various available devices.

METHODS

Three-dimensional scanning, micro-computed tomography imaging, analytical methods, and mechanical tests were used to compare 3 Edwards Lifesciences (Irvine, CA) and 3 Medtronic (Minneapolis, MN) annuloplasty devices of all available sizes. We measured in-plane metrics of maximum diameter, perimeter, area, height, as well as elevation and curvature profiles. Furthermore, we computed bending stiffness as well as the maximum and minimum axes of the bending stiffness.

RESULTS

Most annular prostheses differed little in their in-plane geometries but varied significantly in height. In-plane properties deviated significantly from measurements of healthy human tricuspid annuli. Height of the Edwards' MC3 and Medtronic's Contour 3D resembled healthy human tricuspid valve annuli, whereas the Edwards' Physio and Classic, and Medtronic's TriAd, did not. Additionally, the elevation profiles of the MC3 and Contour 3D and curvature profiles between all devices were consistent and matched those of healthy human annuli. The tested devices also differed in their bending stiffness, both in terms of absolute values and their maximum and minimum axes.

CONCLUSIONS

Contoured devices, such as Edwards' MC3 and Medtronic's Contour 3D, most accurately resembled the healthy human tricuspid annulus but differed significantly in bending stiffness. To what extent prosthesis properties and shape affect tricuspid valve function remains to be determined.

Flexible or rigid ring in mitral annuloplasty-do the results differ?

Introduction

Mitral valve annuloplasty has evolved over the decades since its introduction and Carpentier played a major role in developing the technique. Mitral valve repair is preferred over replacement for severe primary mitral regurgitation, as it restores normal life expectancy when successful and does not require lifelong anticoagulation. There is an ongoing debate regarding the choice of ring for mitral valve annuloplasty-rigid or flexible. At present, the choice of ring is based on the availability of the ring and left to the surgeon's discretion.

Methodology

This is a retrospective study conducted at a tertiary referral centre.

Aim

To compare the outcomes of mitral valve repair annuloplasty with flexible and rigid rings. The hospital records of 112 patients who underwent mitral valve annuloplasty between January 2010 and December 2014 at our hospital were studied. All patients were followed up for 5 years. The rigid and flexible groups were compared for left ventricular (LV) size regression and the presence of mitral regurgitation (MR).

Results

One hundred and eight patients had no progression of mitral regurgitation at 5-year follow-up, compared with the immediate postoperative period. The choice of the ring (rigid and flexible) did not affect the recurrence of mitral regurgitation. At 5-year follow-up, three patients (2 patients in the rigid group and 1 patient in the flexible group) had 3+ MR. One of the two patients in the rigid group had poor functional status and underwent mitral valve replacement (MVR). The other two patients (one in the rigid group and one in the flexible group) with 3+ MR had class II NYHA symptoms and were on medical follow-up. The left ventricular internal diameter diastolic (LVIDD) measured 59.1 mm in the flexible ring group and 56.76 mm in the rigid group preoperatively and these values reduced to 48.4 mm and 47.3 mm, at 5-year follow-up respectively. The mean left ventricular internal diameter systolic (LVIDS) size regression at 5 years was 4.5 ± 6.09 mm in the flexible ring group and 3.2 ± 7.17 mm in the rigid ring group and the difference is not statistically significant (p value 0.314). The mean LVIDD size regression at 5 years was 10.62 ± 6.57 mm in the flexible ring group and 9.38 ± 9.29 mm in the rigid ring group and the difference is not statistically significant (p value 0.408).

Conclusion

The choice of rigid or flexible ring did not have a marked difference on the outcome of mitral valve annuloplasty at midterm follow-up.

Persistent reduction of mitral regurgitation by implantation of a transannular mitral bridge: durability and effectiveness of the repair at 2 years-results of a prospective trial†

OBJECTIVES

Ring annuloplasty reduces the septal-lateral diameter (SLD) indirectly by circumferential annular cinching and frequently results in the recurrence of mitral regurgitation (MR) in patients with functional MR (FMR). Our goal was to report the results from the trial and the 2-year post-trial surveillance data. We evaluated whether direct reduction of the SLD with a transannular mitral bridge could achieve significant and durable MR reduction in patients with FMR.

METHODS

In a prospective trial, 34 consecutive patients with FMR had a mitral bridge implanted surgically. Primary end points were MR ≤1+ at 1, 3 and 6 months postimplant and freedom from subsequent surgical mitral valve repair or replacement.

RESULTS

Thirty-two of 34 (94.1%) patients met the primary end points with MR ≤1+ at 6 months. At 2 years, there were no strokes or device-related adverse events. At 2 years, MR was reduced from 3.32 ± 0.47 to 0.50 ± 0.83 (P ≤ 0.001) with ≤1+ MR in 33/34 patients, including 4 reinterventions for periprosthetic recurrent MR ≥3 without mitral bridge explants or conventional mitral repair or replacement. At 2 years, the mean mitral gradient was 2.15 ± 0.82 mmHg; the mitral annular SLD decreased from 40.4 ± 2.91 mm to 28.9 ± 1.55 mm (P ≤ 0.001). The left ventricular ejection fraction increased (57.9 ± 10.4-62.4 ± 9.7%; P ≤ 0.001). The New York Heart Association functional class improved (2.19 ± 0.76-1.41 ± 0.61; P ≤ 0.001).

CONCLUSIONS

The single-centre trial data indicate that direct reduction in the SLD with a mitral bridge is feasible, safe and efficacious in patients with FMR. Validation in a larger population of patients and comparison to conventional annuloplasty ring are necessary.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03511716.

Influences of mitral annuloplasty on left ventricular flow dynamics assessed with 3-dimensional cine phase-contrast flow magnetic resonance imaging

OBJECTIVES

We assessed the influence of annuloplasty procedures in mitral repair on left ventricular (LV) vortex flow patterns and aortic outflow patterns, and flow energy loss (EL).

METHODS

Twenty healthy volunteers and 14 patients who had undergone mitral valve repair were examined using 3-dimensional cine phase-contrast magnetic resonance imaging. A band group included 7 patients with semi-rigid and 2 with flexible partial bands. The ring group included 5 patients with semi-rigid complete rings. LV vortex flow patterns, aortic outflow patterns, EL, and aortic annulus changes during one cardiac cycle were evaluated.

RESULTS

Mitral repair induced different vortex flow patterns compared with that of healthy volunteers. The vortex beneath the anterior mitral leaflet with semi-rigid devices was double-stranded in early diastole, and it was single-stranded with flexible bands with a large shift toward the apex during diastole. LVEL in patients who underwent mitral repair (0.84 ± 0.42 mW) was greater than that in healthy volunteers (0.47 ± 0.10 mW). Complete rings disturbed aortic outflow patterns, with EL distribution changes. Smaller devices relative to patient body size disturbed LV flow patterns and caused high EL. No significant relationship was found between indexed ring orifice area and transmitral mean pressure gradient (r = -0.25, P = .414), but a negative relationship exists between indexed ring orifice area and LVEL (r = -0.84, P < .001).

CONCLUSIONS

Mitral repair, especially with relatively small annuloplasty rings, induced abnormal LV flow patterns and EL elevation, which have the potential to be a novel hemodynamic evaluation method after mitral repair.

Effect of an artificial ring on mitral valve function

Differences of the effect of annuloplasty rings on the mitral annulus and leaflets, and differences between types of annuloplasty rings are not well known. We analyzed annular motion and leaflet movement with a rigid or flexible ring and without a ring using an isolated swine working heart model. Hearts of 10 swine (weight: 40–50 kg) were used for a rigid ring (n=5) and a flexible ring (n=5). Four ultrasound crystal tips were fixed around the annulus and an annuloplasty ring was implanted in the isolated heart. In the working heart mode, measurement of mitral annular dimension was acquired by sonomicrometry. Images of mitral valve motion were acquired by a high-speed video camera. The same analyses were performed after removing the artificial ring. The antero-posterior diameter of the diastole distance was significantly reduced in the flexible ring (21.59±0.71 mm) and rigid ring (15.93±1.88 mm) compared with no ring (23.51±2.01 mm). The flexible ring made the transverse diameter shrink significantly more than did the rigid ring. The contraction range of the transverse diameter was significantly smaller in the flexible ring compared with no ring. The duration of opening to closing of the mitral leaflet with the rigid (124.7±4.4 ms) and flexible rings (107.9±3.5 ms) was significantly shorter than that with no ring (168±36.5 ms). Annuloplasty rings allow simplicity of leaflet motion, regardless of the type of artificial ring. In a flexible ring, the mitral annulus shows a vertically long shape, suggesting preservation of posterior annular movement.

Mid-term results of mitral valve repair using flexible bands versus complete rings in patients with degenerative mitral valve disease: a prospective, randomized study

Background

We aimed to compare the outcomes of mitral valve repair with flexible band (FB) versus complete semirigid ring (SR) in degenerative mitral valve disease patients.

Methods

From September 2011 to 2014, 171 patients were randomized and underwent successful mitral valve repair using a SR (n = 85) or FB (n = 86). There were no significant between-group differences at baseline.

Results

There were no early mortalities. The mean follow up was 24.7 months. The 2-year survival was 96.0 ± 2.3% (95% confidence interval [CI], 88.6–98.7%) and 94.3 ± 2.8% (95% CI, 85.5–97.9%) in the SR and FB groups, respectively (p = 0.899). The left ventricle remodeling was similar between the groups. Higher transmitral peak (8.5 [3.9–17] vs. 6 [2.1–18] mmHg, p < 0.001), mean pressure gradients (3.7 [1.3–8] vs. 2.8 [0.6–6.8] mmHg, p = 0.001), and systolic pulmonary artery pressure (34.5 [20–68] vs. 29.5 [8–48] mmHg, p < 0.001) was observed in the SR group. The 2-year freedom from recurrence of significant mitral regurgitation was significantly higher in the FB group than the SR group (p = 0.002). Residual mitral regurgitation was an independent prognostic factor of recurrence of mitral regurgitation. The 3-year freedom from reoperation was significantly higher in the FB group than the SR group (p = 0.044).

Conclusion

Patients with degenerative mitral valve disease may benefit from valve repair with FBs. Residual mitral regurgitation before discharge is an independent risk factor of late insufficiency recurrence.

Trial registration

ClinicalTrials.gov NCT03278574, retrospectively registered on 06.09.2017.

Electronic supplementary material

The online version of this article (10.1186/s13019-017-0679-0) contains supplementary material, which is available to authorized users.

High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI

Imaging techniques of the mitral valve have improved tremendously during the last decade, but challenges persist. The delicate changes in annulus shape and papillary muscle position throughout the cardiac cycle have significant impact on the stress distribution in the leaflets and chords, thus preservation of anatomically accurate positioning is critical. The aim of this study was to develop an in vitro method and apparatus for obtaining high-resolution 3D MRI images of porcine mitral valves in both the diastolic and systolic configurations with physiologically appropriate annular shape, papillary muscle positions and orientations, specific to the heart from which the valve was harvested. Positioning and mounting was achieved through novel, customized mounting hardware consisting of papillary muscle and annulus holders with geometries determined via pre-mortem ultrasonic intra-valve measurements. A semi-automatic process was developed and employed to tailor Computer Aided Design models of the holders used to mount the valve. All valve mounting hardware was 3D printed using a stereolithographic printer, and the material of all fasteners used were brass for MRI compatibility. The mounted valves were placed within a clear acrylic case, capable of holding a zero-pressure and pressurized liquid bath of a MRI-compatible fluid. Obtaining images from the valve submerged in liquid fluid mimics the natural environment surrounding the valve, avoiding artefacts due to tissue surface tension mismatch and gravitational impact on tissue shape when not neutrally buoyant. Fluid pressure was supplied by reservoirs held at differing elevations and monitored and controlled to within ±1mmHg to ensure that the valves remained steady. The valves were scanned in a 7 Tesla MRI system providing a voxel resolution of at least 80μm. The systematic approach produced 3D datasets of high quality which, when combined with physiologically accurate positioning by the apparatus, can serve as an important input for validated computational models.

The geometric model of the human mitral valve

The mitral valve, which lies between the left atrium and the left ventricle, plays an important role in controlling the uniflux of blood from the left atrium to the left ventricle as one of the four human heart valves. A precise description of the shape of human mitral valve has vital significance in studying its physiological structure and periodic movement. Unsatisfyingly, there is almost no unified mathematical description of the same shape of human mitral valve in literature. In this paper, we present a geometric model for human mitral valve, as an elastic shell with a special shape. Parametric equations for the shape of human mitral valve are provided, including the anterior and the posterior parts, which can be thought as portions of two interfacing semi-elliptic cylindrical shells. The minor axis of one ellipse is equal to the major axis of the other. All the parameters are determined from the statistical data. Comparison of fitting results with existing examples validates the accuracy of our geometric model. Based on the fitting shape, one can further simulate the physiological function of the mitral valve using a suitable dynamic physical equation.

Computational virtual evaluation of the effect of annuloplasty ring shape

Mitral regurgitation (MR) is a result of mitral valve (MV) pathology. Its etiology can be categorized as degenerative or functional MR. Ring annuloplasty aims to reconfigure a dilated mitral annulus to its normal size and shape. We investigated the effect of annuloplasty ring shape on MR outcome using our established 3-dimensional (3-D) echocardiography-based computational MV evaluation protocols. Virtual patient MV models were created from 3-D transesophageal echocardiographic data in patients with MR because of mitral annular dilation. Two distinct annuloplasty rings (Physio II and GeoForm) were designed and virtually implanted to the patient MVs. Dynamic finite element simulations of MV function were performed for each MV after virtual ring annuloplasty of either ring, and physiologic and biomechanical characteristics of MV function were compared. Excessive stress values appeared primarily in the midanterior and midposterior regions, and lack of leaflet coaptation was found in pre-annuloplasty patient MVs. Both rings demonstrated marked reduction of stresses and efficient leaflet coaptation. The Physio II ring demonstrated more evenly distributed stress reduction across the leaflets and annulus compared with the GeoForm ring. Conversely, the highly nonplanar curvature of the GeoForm ring more effectively increased leaflet coaptation compared with the Physio II ring. This indicates that the shape of annuloplasty ring affects post-annuloplasty physiologic and biomechanical conditions, which can lead to tissue alteration over a longer period after ring annuloplasty. This virtual ring annuloplasty simulation strategy provides detailed physiologic and biomechanical information and may help better plan the optimal ring selection and improved patient-specific MV repairs.

Mitral Valve Annuloplasty with Carpentier-Edwards Physio Ring: Mid-term Results

The mid-term results of mitral valve repair with the Carpentier-Edwards Physio annuloplasty ring were assessed in 97 consecutive patients in a single tertiary-referral cardiothoracic surgical center. The mean follow-up time was 3.9 years (range, 1 month to 8.9 years). Most patients were in functional class II and III before the operation. Ejection fraction was < 40% in 8 patients. Causes of mitral regurgitation included degenerative disease (66%), infective endocarditis (13.4%), rheumatic disease (10.3%), and ischemic heart disease (9.3%). Thirty-day mortality was 2.1%. Actuarial survival and freedom from re-operation at 8 years were 91% and 90.8%, respectively. The only significant risk factor for re-operation was residual mitral regurgitation. Four patients suffered thromboembolic complications, giving an overall event-free survival of 93% ± 3.7% during the follow-up period. The Carpentier-Edwards Physio ring provides safe and effective repair of mitral regurgitation on mid-term follow-up.

Comparison of saddle-shape flexibility and elliptical-shape stability between Cosgrove-Edwards and Memo-3D annuloplasty rings using three-dimensional analysis software

OBJECTIVE

To compare three-dimensional dynamics between implanted Cosgrove-Edwards and Sorin Memo-3D annuloplasty rings during the cardiac cycle.

METHODS

We examined 11 Cosgrove-Edwards rings and 20 Sorin Memo-3D rings after mitral plasty using real-time three-dimensional transesophageal echocardiography. We evaluated ring height, ellipticity, and geometry during one cardiac cycle. Four evenly spaced phases each selected during systole and diastole were assessed using REAL VIEW software.

RESULTS

The height of the Cosgrove-Edwards and Sorin Memo-3D rings was similar (2.3 ± 0.8 vs. 1.9 ± 0.9 mm, p = 0.44). The maximum difference in ring height during one cardiac cycle (change in height) was larger for the Cosgrove-Edwards than the Sorin Memo-3D rings (2.3 ± 0.8 vs. 1.5 ± 0.6 mm, p = 0.014). Ellipticity and the maximum difference in ellipticity during one cardiac cycle (change in ellipticity) were larger for Cosgrove-Edwards than Sorin Memo-3D rings (80.0 ± 9.1 vs. 72.0 ± 4.8 %, p = 0.014, respectively, and 12.0 ± 3.1 vs. 6.0 ± 1.8 %, p < 0.001).

CONCLUSIONS

Cosgrove-Edwards rings were more flexible, whereas Sorin Memo-3D rings maintained the elliptical shape more effectively.

Movement of mitral fibrous components in an isolated porcine working heart model

BACKGROUND

There is little research regarding the movement of mitral fibrous components. We analyzed changes in mitral fibrous components in normal and deteriorated isolated working swine hearts.

METHODS

In 5 swine hearts, 6 sonomicrometry transducers were placed around the mitral annulus and 2 in the papillary muscle tip. During the working cycle, we evaluated the annular dimension and calculated the contraction range and contraction ratio during the cardiac cycle in normal and deteriorated modes.

RESULTS

The transverse (24.5 ± 2.3 vs. 27.4 ± 2.4 mm) and posterior longitudinal diameter (18.3 ± 7.0 vs. 22.5 ± 5.5 mm) increased significantly in deteriorated mode. The contraction range in transverse (1.8 ± 0.6 vs. 0.8 ± 0.7 mm) and posterior longitudinal (1.6 ± 0.6 vs. 0.8 ± 0.3 mm) diameters decreased significantly in deteriorated mode. The contraction range of the strut chordae was less than 1.0 mm in both modes, with no significant differences. The contraction ratio of the anterior strut chordae was significantly reduced in deteriorated mode (3.2 ± 1.1% vs. 2.2 ± 1.1%). The contraction ratio of the annulus was significantly lower in deteriorated mode with respect to transverse (6.9 ± 2.1% vs. 2.9 ± 2.9%) and longitudinal (13.3 ± 4.5% vs. 8.6 ± 5.1%) diameters.

CONCLUSIONS

In the deteriorated hearts, the mitral annulus was dilated and contractility decreased. The length of the strut chordae differed 1 mm between the deteriorated and normal modes; however, the contraction ratio of the anterior chordae during the cardiac cycle was reduced, indicating increased stretching.

Mitral Valve Annuloplasty Rings: Review of Literature and Comparison of Functional Outcome and Ventricular Dimensions

In the past decades, more than 40 mitral valve annuloplasty rings of various shapes and consistency were marketed for mitral regurgitation (MR), although the effect of ring type on clinical outcome remains unclear. Our objective was to review the literature and apply a simplification method to make rings of different shapes and rigidity more comparable. We studied relevant literature from MEDLINE and EMBASE databases related to clinical studies as well as animal and finite element models. Annuloplasty rings were clustered into 3 groups as follows: rigid (R), flexible (F), and semirigid (S). Only clinical articles regarding degenerative (DEG) or ischemic/dilated cardiomyopathy (ICM) MR were included and stratified into these groups. A total of 37 rings were clustered into R, F, and S subgroups. Clinical studies with a mean follow-up of less than 1 year and a reported mean etiology of valve incompetence of less than 60% were excluded from the analysis. Forty-one publications were included. Preimplant and postimplant end points were New York Heart Association class, left ventricular ejection fraction (LVEF), left ventricular end-systolic dimension (LVESD), and left ventricular end-diastolic dimension (LVEDD). Statistical analysis included paired-samples t test and analysis of variance with post hoc Bonferroni correction. P < 0.05 indicated statistical difference. Mean ± SD follow-up was 38.6 ± 27 and 29.7 ± 13.2 months for DEG and ICM, respectively. In DEG, LVEF remained unchanged, and LVESD decreased in all subgroups. In our analysis, LVEDD decreased only in F and R, and S did not change; however, the 4 individual studies showed a significant decline. In ICM, New York Heart Association class improved in all subgroups, and LVEF increased. Moreover, LVESD and LVEDD decreased only in F and S; R was underpowered (1 study). No statistical difference among R, F, and S in either ICM or DEG could be detected for all end points. Overall, owing to underpowered data sets derived from limited available publications, major statistical differences in clinical outcome between ring types could not be substantiated. Essential end points such as recurrent MR and survival were incomparable. In conclusion, ring morphology and consistency do not seem to play a major clinical role in mitral valve repair based on the present literature. Hence, until demonstrated otherwise, surgeons may choose their ring upon their judgment, tailored to specific patient needs.

FINITE ELEMENT MODELING OF THE HUMAN MITRAL VALVE: IMPLICATIONS OF MORPHOLOGIES AND DYNAMICS OF THE ANNULUS AND THE CHORDAE TENDINEAE

Objectives: To investigate the influences caused by special morphologies and dynamics of the substructures of mitral valve by the explicit finite element program LS-DYNA. Methods: A new finite element model for the mitral apparatus characterized by layered structure of leaflets tissue, saddle shape and contraction of annulus, an approximately accurate morphology of chordae tendineae was developed. The coaptation length, leaflets stress and strain of the present model were compared with those of two auxiliary models, one with planar annulus and the other with fixed annulus. The tensile function and force distribution of chordae tendineae were analyzed in the models with and without chordae tendineae. Results: The stretch ratios computed by the present model were most closely to the experimental data. The leaflets instantly turned over to the atrial side and larger load was observed in the model without chordae tendineae. Besides, tensile force was highly correlated with average diameter of chordae tendineae (r = 0.965). Conclusion: The saddle shape of annulus benefits valve coaptation and the contraction of annulus could help decrease loads on leaflets and prevent stress concentrating excessively. Chordae tendineae could bear partial loads on the leaflets, and prevent the leaflets to turn over to the side of the atrium and help the valve close successfully.

Mitral annulus segmentation from four-dimensional ultrasound using a valve state predictor and constrained optical flow

Measurement of the shape and motion of the mitral valve annulus has proven useful in a number of applications, including pathology diagnosis and mitral valve modeling. Current methods to delineate the annulus from four-dimensional (4D) ultrasound, however, either require extensive overhead or user-interaction, become inaccurate as they accumulate tracking error, or they do not account for annular shape or motion. This paper presents a new 4D annulus segmentation method to account for these deficiencies. The method builds on a previously published three-dimensional (3D) annulus segmentation algorithm that accurately and robustly segments the mitral annulus in a frame with a closed valve. In the 4D method, a valve state predictor determines when the valve is closed. Subsequently, the 3D annulus segmentation algorithm finds the annulus in those frames. For frames with an open valve, a constrained optical flow algorithm is used to the track the annulus. The only inputs to the algorithm are the selection of one frame with a closed valve and one user-specified point near the valve, neither of which needs to be precise. The accuracy of the tracking method is shown by comparing the tracking results to manual segmentations made by a group of experts, where an average RMS difference of 1.67±0.63mm was found across 30 tracked frames.

A novel shape memory alloy annuloplasty ring for minimally invasive surgery: design, fabrication, and evaluation

A novel annuloplasty ring with a shape memory alloy core has been developed to facilitate minimally invasive mitral valve repair. In its activated (austenitic) phase, this prototype ring has comparable mechanical properties to commercial semi-rigid rings. In its pre-activated (martensitic) phase, this ring is flexible enough to be introduced through an 8-mm trocar and easily manipulated with robotic instruments within the confines of a left atrial model. The core is constructed of 0.50 mm diameter NiTi, which is maintained below its martensitic transition temperature (24 °C) during deployment and suturing. After suturing, the ring is heated above its austenitic transition temperature (37 °C, normal human body temperature) enabling the NiTi core to attain its optimal geometry and stiffness characteristics indefinitely. This article summarizes the design, fabrication, and evaluation of this prototype ring. Experimental results suggest that the NiTi core ring could be a viable alternative to flexible bands in robot-assisted minimally invasive mitral valve repair.

Mitral annulus segmentation from 3D ultrasound using graph cuts

The shape of the mitral valve annulus is used in diagnostic and modeling applications, yet methods to accurately and reproducibly delineate the annulus are limited. This paper presents a mitral annulus segmentation algorithm designed for closed mitral valves which locates the annulus in three-dimensional ultrasound using only a single user-specified point near the center of the valve. The algorithm first constructs a surface at the location of the thin leaflets, and then locates the annulus by finding where the thin leaflet tissue meets the thicker heart wall. The algorithm iterates until convergence metrics are satisfied, resulting in an operator-independent mitral annulus segmentation. The accuracy of the algorithm was assessed from both a diagnostic and surgical standpoint by comparing the algorithm's results to delineations made by a group of experts on clinical ultrasound images of the mitral valve, and to delineations made by an expert with a surgical view of the mitral annulus on excised porcine hearts using an electromagnetically tracked pointer. In the former study, the algorithm was statistically indistinguishable from the best performing expert (p=0.85) and had an average RMS difference of 1.81+/-0.78 mm to the expert average. In the latter, the average RMS difference between the algorithm's annulus and the electromagnetically tracked points across six hearts was 1.19+/-0.17 mm .

Mitral Valve Finite Element Modeling: Implications of Tissues’ Nonlinear Response and Annular Motion

Finite element modeling represents an established method for the comprehension of the mitral function and for the simulation of interesting clinical scenarios. However, current models still do not include all the key aspects of the real system. We implemented a new structural finite element model that considers (i) an accurate morphological description of the valve, (ii) a description of the tissues’ mechanical properties that accounts for anisotropy and nonlinearity, and (iii) dynamic boundary conditions that mimic annulus and papillary muscles’ contraction. The influence of such contraction on valve biomechanics was assessed by comparing the computed results with the ones obtained through an auxiliary model with fixed annulus and papillary muscles. At the systolic peak, the leaflets’ maximum principal stress contour showed peak values in the anterior leaflet at the strut chordae insertion zone (300 kPa) and near the annulus (200–250 kPa), while much lower values were detected in the posterior leaflet. Both leaflets underwent larger tensile strains in the longitudinal direction, while in the circumferential one the anterior leaflet experienced nominal tensile strains up to 18% and the posterior one experienced compressive strains up to 23% associated with the folding of commissures and paracommissures, consistently with tissue redundancy. The force exerted by papillary muscles at the systolic peak was equal to 4.11 N, mainly borne by marginal chordae (76% of the force). Local reaction forces up to 45 mN were calculated on the annulus, leading to tensions of 89 N/m and 54 N/m for its anterior and posterior tracts, respectively. The comparison with the results of the auxiliary model showed that annular contraction mainly affects the leaflets’ circumferential strains. When it was suppressed, no more compressive strains could be observed and peak strain values were located in the belly of the anterior leaflet. Computational results agree to a great extent with experimental data from literature. They provided insight into some of the features characterizing normal mitral function, such as annular contraction and leaflets’ tissue anisotropy and nonlinearity. Some of the computed results may be useful in the design of surgical devices and techniques. In particular, forces applied on the annulus by the surrounding tissues could be considered as an indication for annular prostheses design.

Evaluation of a shape memory alloy reinforced annuloplasty band for minimally invasive mitral valve repair

PURPOSE

An in vitro study using explanted porcine hearts was conducted to evaluate a novel annuloplasty band, reinforced with a two-phase, shape memory alloy, designed specifically for minimally invasive mitral valve repair.

DESCRIPTION

In its rigid (austenitic) phase, this band provides the same mechanical properties as the commercial semi-rigid bands. In its compliant (martensitic) phase, this band is flexible enough to be introduced through an 8-mm trocar and is easily manipulated within the heart.

EVALUATION

In its rigid phase, the prototype band displayed similar mechanical properties to commercially available semi-rigid rings. Dynamic flow testing demonstrated no statistical differences in the reduction of mitral valve regurgitation. In its flexible phase, the band was easily deployed through an 8-mm trocar, robotically manipulated and sutured into place.

CONCLUSIONS

Experimental results suggest that the shape memory alloy reinforced band could be a viable alternative to flexible and semi-rigid bands in minimally invasive mitral valve repair.

Mitral annular hinge motion contribution to changes in mitral septal-lateral dimension and annular area

OBJECTIVE

The mitral annulus is a dynamic, saddle-shaped structure consisting of fibrous and muscular regions. Normal physiologic mechanisms of annular motion are incompletely understood, and more complete characterization is needed to provide rational basis for annuloplasty ring design and to enhance clinical outcomes.

METHODS

Seventeen sheep had radiopaque markers implanted; 16 around the annulus and 2 on middle anterior and posterior leaflet edges. Four-dimensional marker coordinates were acquired with biplanar videofluoroscopy at 60 Hz. Hinge angle was quantified between fibrous and muscular annular planes, with 0 degrees defined at end diastole, to characterize its contribution to alterations in mitral septal-lateral dimension and 2-dimensional total annular area throughout the cardiac cycle.

RESULTS

During isovolumic contraction (pre-ejection), hinge angle abruptly increased, reaching maximum (steepest saddle shape, change 18 degrees +/- 13 degrees ) at peak left ventricular pressure. During ejection, hinge angle did not change; it then decreased during early filling (change 2 degrees +/- 2 degrees ). Septal-lateral dimension and total area paralleled hinge angle dynamics and leaflet distance (anterior to posterior marker). Pre-ejection septal-lateral reduction was 13% +/- 7% (3.3 +/- 1.5 mm) from 9% muscular dimension fall and 18 degrees +/- 13 degrees hinge angle increase.

CONCLUSIONS

Pre-ejection increase in hinge angle contributes substantially to septal-lateral and total area reduction, facilitating leaflet coaptation. Semirigid annuloplasty rings or partial bands may preserve hinge motion, but possible recurrent annular dilatation could result in recurrent mitral regurgitation. Long-term clinical studies are required to determine who might benefit most from preserving intrinsic hinge motion without compromising repair durability.

Toward the development of a fully elastic mitral ring: preliminary, acute, in vivo evaluation of physiomechanical behavior

OBJECTIVES

The optimal repair of functional mitral regurgitation is still debated. No device is able to simultaneously abolish mitral regurgitation and replicate natural mitral annular dynamics. We have tested a fully elastic mitral ring in an acute animal study with the purpose of evaluating (1) ring design and implantation technique, (2) elastic performance, and (3) acute effects on the native mitral annulus.

METHODS

Ten healthy sheep underwent surgical implantation of mitral devices, the elastic component of which is represented by a helicoid metallic spring. Preimplantation and postimplantation echocardiographic parameter measurements to evaluate annular dynamics and ventricular function comprise mitral annular motion, systolic tissue Doppler imaging peak wave, transmitral pressure gradient, peak transmitral flow velocity, and ejection fraction. Postimplantation angiographic analysis allowed measurement of the mitral annular area and perimeter variations by means of segmentation of the radiopaque mitral device contour.

RESULTS

No significant difference in terms of ejection fraction (P = .13) and systolic tissue Doppler imaging peak wave (P = .87) was found before and after implantation. Mitral annular motion (1.16 cm) was preserved. The percentage of systolic annular reduction derived from angiographic analysis was 14.1% (range, 7.7%-19.7%) in terms of area and 7.2% (range, 4.9%-10.0%) in terms of perimeter.

CONCLUSIONS

A mitral elastic ring, implantable by using a standard technique, acutely preserves mitral annular dynamics, allowing area and perimeter changes. Further chronic study is needed to verify the biocompatibility and durability of the device.

Mitral valve finite-element modelling from ultrasound data: a pilot study for a new approach to understand mitral function and clinical scenarios

In the current scientific literature, particular attention is dedicated to the study of the mitral valve and to comprehension of the mechanisms that lead to its normal function, as well as those that trigger possible pathological conditions. One of the adopted approaches consists of computational modelling, which allows quantitative analysis of the mechanical behaviour of the valve by means of continuum mechanics theory and numerical techniques. However, none of the currently available models realistically accounts for all of the aspects that characterize the function of the mitral valve. Here, a new computational model of the mitral valve has been developed from in vivo data, as a first step towards the development of patient-specific models for the evaluation of annuloplasty procedures. A structural finite-element model of the mitral valve has been developed to account for all of the main valvular substructures. In particular, it includes the real geometry and the movement of the annulus and papillary muscles, reconstructed from four-dimensional ultrasound data from a healthy human subject, and a realistic description of the complex mechanical properties of mitral tissues. Preliminary simulations allowed mitral valve closure to be realistically mimicked and the role of annulus and papillary muscle dynamics to be quantified.

The Geoform disease-specific annuloplasty system: a finite element study

BACKGROUND

Functional mitral regurgitation (FMR) is the inability of mitral leaflets to coapt due to a combination of functional and geometrical factors. Valve competence is commonly restored by undersized annuloplasty, reducing the native annulus anteroposterior dimension. In case of severe FMR, this solution may be inadequate. The use of rings specific for the correction of FMR may lead to better results.

METHODS

The performance of the Geoform ring, a recently designed FMR-specific prosthesis, was compared with that of a standard Physio annuloplasty ring. Finite element modeling was used to simulate dilated cardiomyopathy-related FMR and compare, at the systolic peak, the valve's pathologic condition with the postoperative scenario corresponding to both devices. Three degrees of the pathology were simulated by progressively displacing papillary muscles apically, up to 5 mm. Three ring sizes were modeled.

RESULTS

Regurgitant area, coaptation length, and stresses acting on valve structures were assessed. When the use of the Geoform was modeled, coaptation length was always longer than 7 mm. In the most unfavorable case, the regurgitant area reduction was 74% with respect to baseline, and leaflets stresses were reduced by 20% when undersizing was simulated. When Physio ring implantation was simulated, coaptation length maximum extent was equal to 4.3 mm, the maximum regurgitant area reduction was equal to 60%, and leaflet stress reduction was observed.

CONCLUSIONS

Disease-specific prostheses may allow for restoration of valve competence even for significant degrees of leaflets tethering and avoid the need for aggressive undersizing, thus leading to more durable results.

Percutaneous Septal Sinus Shortening

Background— The septal-to-lateral (SL) mitral annular diameter is increased in functional mitral regurgitation (MR). We describe a novel percutaneous technique (the percutaneous septal sinus shortening system) that ameliorates functional MR in an ovine model.

Methods and Results— Sheep underwent rapid right ventricular pacing to obtain moderate to severe functional MR with SL enlargement. The percutaneous septal sinus shortening system was placed via standard interventional techniques consisting of a bridge (suture) element between interatrial septal wall and great cardiac vein anchors. Through progressive tensioning of the bridge element, direct SL shortening was achieved. Sheep underwent short-term (n=19) and long-term (n=4) evaluation after device implantation. In short-term studies, SL diameter decreased an average of 24% (32.5±3.5 to 24.6±2.4 mm; P <0.001), and MR grade significantly improved (2.1±0.6 to 0.4±0.4; P <0.001). Despite continued rapid pacing, chronic device implantation resulted in durable SL shortening (30.4±1.9 mm before implantation to 25.3±0.8 mm at 30 days; P =0.01) and MR reduction (1.8±0.5 before implantation to 0.2±0.1 at 30 days; P =0.01). Increased cardiac output, decreased wedge pressure, and decreased brain natriuretic peptide levels were observed in animals undergoing long-term device implantation.

Conclusions— The percutaneous septal sinus shortening system is effective in ameliorating functional MR in an ovine tachycardia model. The procedure, which uses standard catheter techniques, can be deployed largely under fluoroscopic guidance. The unique bridge element appears durable and allows direct and precise SL shortening to a diameter optimal for MR reduction.

Sovering annuloplasty rings: experimental pathology in the sheep model

INTRODUCTION

A new flexible annuloplasty ring (Sovering, Sorin Biomedica Cardio), both closed and open, has been designed and consists of radiopaque silicone core impregnated with barium sulfate and covered by a knitted polyester fabric coated with Carbofilm. The aim of the study was to test the biological compatibility of the new device in large animals in orthotopic position.

METHODS

Ten Sovering rings were implanted in 10 female adult sheep, 7 mitral (3 open, 4 closed) and 3 tricuspid (all open). The size was 23-25 mm in the mitral and 28-30 mm in the tricuspid position, and the time in place varied from 63 to 110 days (mean = 89 +/- 14) and from 58 to 63 days (mean = 61 +/- 3), respectively. The morphological analysis consisted of gross, histological, immunohistochemical and ultrastructural investigations.

RESULTS

The prosthetic ring appeared well implanted in the valve atrioventricular (AV) junction, encapsulated by a thin fibrous sheath without any evidence of thrombus deposition, fibrinous lining or exuberant fibrous tissue overgrowth. No adverse inflammatory reaction was observed, but rare lymphocytes, macrophages and foreign body giant cells. At electron microscopy, the fibrous tissue appeared to permeate deeply within the fabric network; reendothelization on the surface was noted and confirmed by immunohistochemistry. Sirius red staining at polarized light revealed a higher content of collagen type III in the mitral than in the tricuspid position.

CONCLUSIONS

Sovering annuloplasty rings implanted in the AV valves of adult sheep showed excellent biocompatibility, fibrous encapsulation and reendothelization. The absence of thrombosis and exuberant fibrous tissue reaction supports the effective use of Carbofilm covering in annuloplasty devices.

Geometric changes of mitral annulus assessed by real-time 3-dimensional echocardiography: Becoming enlarged and less nonplanar in the anteroposterior direction during systole in proportion to global left ventricular systolic function

OBJECTIVE

We sought to investigate the geometric changes of the mitral annulus during systole in relation to global left ventricular (LV) systolic function using real-time 3-dimensional (3D) echocardiography.

METHODS

Real-time 3D echocardiography was performed in 23 patients with global LV systolic dysfunction with ejection fraction of 37 +/- 19% and 9 control subjects with ejection fraction of 62 +/- 4%. Volumetric data were divided into 9 rotational apical planes (angle increment = 20 degrees) using 3D software. Nine rotational annular dimensions (ADs) were measured in all planes in early and late systole. Nonplanar angle (NPA) of the annulus between two vectors from two hinge points of the annulus in the anteroposterior plane to the center between two commissures in the commissure-commissure plane was measured during early and late systole. Fractional changes of NPA and AD were defined as changes in percentage during systole.

RESULTS

NPA significantly increased during systole (early, 145 +/- 12 degrees; late, 160 +/- 9 degrees; P < .01). Among 9 ADs, 3 anteroposteriorly directed ADs showed the most prominent fractional increases during systole in all patients. Both fractional changes of NPA ( R 2 = 0.87, P < .01) and the anteroposterior dimension, AD 1 ( R 2 = 0.85, P < .01) showed significant positive correlation with global LV systolic function.

CONCLUSIONS

Real-time 3D echocardiography demonstrated that saddle shape of the mitral annulus was getting enlarged and less nonplanar mainly in the anteroposterior direction during systole. These geometric changes were proportional to the global LV systolic function.

Effects of Paracommissural Septal-Lateral Annular Cinching on Acute Ischemic Mitral Regurgitation

BACKGROUND

Previous experimental studies demonstrated that central septal-lateral (SL) annular cinching (SLAC) abolishes acute ischemic mitral regurgitation (IMR), but whether localized cinching near the anterior (ACOM) or posterior (PCOM) commissure is equally effective is unknown.

METHODS

Six adult sheep underwent implantation of 9 radiopaque markers on the left ventricle, 8 around the mitral annulus (MA) and 1 on each papillary muscle (PM) tip. Transannular SL sutures were placed at the valve center (CENT) and near ACOM and PCOM and externalized. Acute IMR was induced by proximal circumflex coronary snare occlusion. Biplane videofluoroscopy and transesophageal echocardiography were performed before and continuously during 3 episodes of myocardial ischemia including 20 seconds of SLAC at each different location. End-systolic MA SL dimension at each suture location and distances between the anterior and posterior PM tips and mid-septal annulus ("saddle horn") were calculated from the 3-dimensional (3D) marker coordinates.

RESULTS

SLAC interventions in all 3 locations reduced the degree of IMR, but cinching at the center, SLAC(CENT), had a significantly greater effect on reducing the magnitude of IMR than SLAC(PCOM) or SLAC(ACOM) (mean grade of IMR reduction=1.0+/-0.5, 1.8+/-0.5, and 0.9+/-0.2 for SLAC(ACOM), SLAC(CENT), and SLAC(PCOM), respectively; P=0.044). Although ACOM and PCOM cinching reduced SL(CENT) somewhat, only SLAC(CENT) simultaneously reduced both SL(ACOM) and SL(PCOM) and also repositioned both PM tips closer to the annular saddle horn.

CONCLUSIONS

SLAC in all 3 positions reduced acute IMR, but central SLAC cinching was most effective, reduced all mitral annular SL dimensions, and relocated both PM tips closer to the mid-septal annulus. Central SLAC is most capable of correcting the annular and subvalvular perturbations accompanying acute left ventricular ischemia that lead to IMR.

Does septal-lateral annular cinching work for chronic ischemic mitral regurgitation?

OBJECTIVES

Ring annuloplasty, the current treatment of choice for chronic ischemic mitral regurgitation, abolishes dynamic annular motion and immobilizes the posterior leaflet. In a model of chronic ischemic mitral regurgitation, we tested septal-lateral annular cinching aimed at maintaining normal annular and leaflet dynamics.

METHODS

Twenty-five sheep had radiopaque markers placed on the mitral annulus and anterior and posterior mitral leaflets. A transannular suture was anchored to the midseptal mitral annulus and externalized through the midlateral mitral annulus. After 7 days, biplane cinefluoroscopy provided 3-dimensional marker data (baseline) prior to creating inferior myocardial infarction by snare occlusion of obtuse marginal branches. After 7 weeks, the 9 animals that developed chronic ischemic mitral regurgitation were restudied before and after septal-lateral annular cinching. Anterior and posterior mitral leaflet angular excursion and annular septal-lateral and commissure-commissure dimensions and percent shortening were computed.

RESULTS

Septal-lateral annular cinching reduced septal-lateral dimension (baseline: 3.0 +/- 0.2; chronic ischemic mitral regurgitation: 3.5 +/- 0.4 [P <.05 vs baseline by repeated measures analysis of variance and Dunnett's test]; septal-lateral annular cinching: 2.4 +/- 0.3 cm; maximum dimension) and eliminated chronic ischemic mitral regurgitation (baseline: 0.6 +/- 0.5; chronic ischemic mitral regurgitation: 2.3 +/- 1.0 [P <.05 vs baseline by repeated measures analysis of variance and Dunnett's test]; septal-lateral annular cinching: 0.6 +/- 0.6; mitral regurgitation grade [0 to 4+]) but did not alter dynamic annular shortening (baseline: 7 +/- 3; chronic ischemic mitral regurgitation: 10 +/- 5; septal-lateral annular cinching: 6 +/- 2, percent septal-lateral shortening) or posterior mitral leaflet excursion (baseline: 46 degrees +/- 8 degrees; chronic ischemic mitral regurgitation: 41 degrees +/- 13 degrees; septal-lateral annular cinching: 46 degrees +/- 8 degrees ).

CONCLUSIONS

In this model, septal-lateral annular cinching decreased chronic ischemic mitral regurgitation, reduced annular septal-lateral diameter (but not commissure-commissure diameter), and maintained normal annular and leaflet dynamics. These findings provide additional insight into the treatment of chronic ischemic mitral regurgitation.

Computer-generated three-dimensional animation of the mitral valve

OBJECTIVE

Three-dimensional motion-capture data offer insight into the mechanical differences of mitral valve function in pathologic states. Although this technique is precise, the resulting time-varying data sets can be both difficult to interpret and visualize. We used a new technique to transform these 3-dimensional ovine numeric analyses into an animated human model of the mitral apparatus that can be deformed into various pathologic states.

METHODS

In vivo, high-speed, biplane cinefluoroscopic images of tagged ovine mitral apparatus were previously analyzed under normal and pathologic conditions. These studies produced serial 3-dimensional coordinates. By using commercial animation and custom software, animated 3-dimensional models were constructed of the mitral annulus, leaflets, and subvalvular apparatus. The motion data were overlaid onto a detailed model of the human heart, resulting in a dynamic reconstruction.

RESULTS

Numeric motion-capture data were successfully converted into animated 3-dimensional models of the mitral valve. Structures of interest can be isolated by eliminating adjacent anatomy. The normal and pathophysiologic dynamics of the mitral valve complex can be viewed from any perspective.

CONCLUSION

This technique provides easy and understandable visualization of the complex and time-varying motion of the mitral apparatus. This technology creates a valuable research and teaching tool for the conceptualization of mitral valve dysfunction and the principles of repair.

Semirigid partial annuloplasty band allows dynamic mitral annular motion and minimizes valvular gradients: an echocardiographic study

BACKGROUND

Traditional mitral annuloplasty devices include both rigid rings, which restrict annular motion, and soft rings and bands, which can locally deform. Conflicting data exist regarding their impact on annular dynamics. We studied mitral annuloplasty with a semirigid partial band and with a nearly complete rigid ring.

METHODS

Intraoperative three-dimensional transesophageal echocardiograms (n = 14) and predischarge transthoracic echocardiograms were retrospectively analyzed in patients undergoing mitral valve repair for degenerative disease with either a rigid ring (n = 77) or a semirigid partial band (n = 38). Each transesophageal echocardiogram was analyzed with TomTec three-dimensional software to produce cardiac cycle frame planimetry and to measure device geometry. Actual device sizes provided reference dimensions. Blinded analysis of Doppler data from transthoracic echocardiograms was performed.

RESULTS

Validation of the quantitative transesophageal echocardiogram methodology revealed a 1.3% +/- 0.3% (mean +/- standard error of the mean) underestimation of actual linear dimension. With the semirigid partial band, systolic valve orifice area and intertrigonal distance decreased from 6.14 +/- 0.37 to 5.55 +/- 0.24 cm(2) (-9.6%; p = 0.01) and from 2.69 +/- 0.08 to 2.55 +/- 0.13 cm (-5.2%; p = 0.03), respectively. Systolic anterior-posterior distance decreased from 2.1 +/- 0.10 to 1.95 +/- 0.06 cm (-7.1%; p = 0.01) compared with diastole. In contrast, rigid ring orifice area was unchanged (4.12 +/- 0.15 to 4.10 +/- 0.16 cm(2); -0.5%; p = 0.48) during the cardiac cycle. Transthoracic echocardiography revealed significantly lower mitral inflow gradients with semirigid partial band (mean gradients compared with rigid ring, 4.0 +/- 0.3 versus 5.0 +/- 0.3 mm Hg; p = 0.02; peak gradients, 8.9 +/- 0.5 versus 11.1 +/- 0.5 mm Hg; p = 0.01).

CONCLUSIONS

Three-dimensional transesophageal echocardiographic measurements of annular dynamics are valid and reliable when discrete annuloplasty devices are present. In contrast to the rigid ring, the semirigid partial band permits more physiologic geometric changes and is associated with lower postoperative mitral valve gradients.