Mitral Annular Dynamics Research Articles

Invited Commentary

Undersizing mitral annuloplasty (UMA) has emerged as a mitral repair technique of choice to correct ischemic mitral regurgitation (IMR). Despite the unphysiological leaflet coaptation that results from this repair and the potential deleterious impact that restricting mitral annular dynamics and basal myocardial contraction may have on left ventricular function, extensive surgical experience with UMA and its procedural ease makes this a procedure of choice. However, to achieve better long-term patient outcomes after UMA, the adverse impact of UMA on the valve and the ventricle needs to be better understood. In this study, Pantoja and colleagues [1Pantoja J.L. Morgan A.E. Grossi E.A. et al.Undersized mitral annuloplasty increases strain in the proximal lateral left ventricular wall.Ann Thorac Surg. 2017; 103: 820-827Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar] use a finite element model of an IMR-like left ventricle to demonstrate that UMA impacts basal myocardial mechanics and acutely alters left ventricular shape. Specifically, the end-diastolic longitudinal strain in the lateral left ventricular wall was elevated when compared with the preoperative configuration, but the fiber strain in the same region was decreased. The authors conclude that UMA induced changes in left ventricular shape and that mechanics can trigger continued remodeling of the ventricle and result in recurrent IMR and poor ventricular function. This is a nicely done computational study, albeit with some limitations, which follow:1.Preannuloplasty annular size and shape—in the clinical scenario, the mitral annular sizes, shapes, and extent of dilatation differs significantly between patients, and the effect of an annuloplasty ring on each annulus may be variable. Despite using 5 sheep-specific models in this study, the variability in annular geometry and its impact on postannuloplasty strains were not investigated.2.Impact of IMR correction—Annuloplasty acutely abolishes IMR and thus reduces. Reduced end-diastolic strain may reduce the impact that the ring may have on the ventricular shape and mechanics. The computational model does not consider the physiological effects of the ring on the ventricle.3.The distinction of the myocardium into layers is only hypothetical and not ultrastructure driven in this model. Specifically, the infarcted myocardium is thinned, lacks distinct layers, and is often stiffened from fibrosis. The computational model did not seem to consider these regional structural features, which may have an impact on the reported strains. Notwithstanding these limitations, this study provides some preliminary insights into the deleterious impact that undersizing annuloplasty may have on the left ventricle. However, whether it causes continued left ventricular remodeling or impairs systolic function remains speculative at best and needs careful experimental validation. In 2012, Shudo and coworkers [2Shudo Y. Nakatani S. Sakaguchi T. et al.Left ventricular mechanics following restrictive mitral annuloplasty for functional mitral regurgitation: two dimensional speckle tracking echocardiographic study.Echocardiography. 2012; 29: 445-450Crossref PubMed Scopus (4) Google Scholar] investigated left ventricular mechanics at 4 weeks after UMA in patients with IMR and reported that ejection fraction and longitudinal strains were largely unaltered. Radial and longitudinal strains were improved at the mid and apical levels but were unaltered at the base of the ventricle. Left ventricular twist was significantly elevated in these patients after UMA, compared with their preoperative measurements. The discrepancy between such improved left ventricular mechanics in patients who underwent UMA and the adverse impact suggested in this simplified computational model will need to be explained for clinical translation of these findings. Undersized Mitral Annuloplasty Increases Strain in the Proximal Lateral Left Ventricular WallThe Annals of Thoracic SurgeryVol. 103Issue 3PreviewRecurrence of mitral regurgitation (MR) after undersized mitral annuloplasty (MA) for ischemic MR is as high as 60%, with the recurrence rate likely due to continued dilation of the left ventricle (LV). To better understand the causes of recurrent MR, we studied the effect of undersized MA on strain in the LV wall. We hypothesize that the acute change in ventricular shape induced by MA will cause increased strain in regions nearest the mitral valve. Full-Text PDF

Mitral Annular Dynamics and Left Ventricular Diastole.

BackgroundThough diastolic interrogation of the mitral annulus (MA) using tissue Doppler imaging (TDI) has been quite useful in assessing left ventricular (LV) diastolic function, the relative contribution of the previous cycle MA systolic displacement or velocity components to subsequent LV diastole has not been previously investigated. We therefore sought to determine the association between MA systolic dynamics and LV diastolic function parameters.MethodsFor this retrospective study, only complete echocardiograms having good endocardial border resolution of both left atrial (LA) and LV chambers with M-mode (MAPSE) and tissue Doppler of the lateral MA (MA TDI S’) as well as complete Doppler data to perform assessment of LV diastole were included in our analysis.ResultsData from 100 patients (mean age 54 ± 14) showed that both MA systolic displacement and velocity correlate with LV ejection fraction (P < 0.05). Only MA displacement was associated with age and LV mass. Most importantly no correlation was found between MAPSE and LV diastole. However, in sharp contrast MA TDI S’ correlated with MA relaxation velocities during both early and late LV diastole.ConclusionEven though MAPSE and MA TDI S’ are surrogate measures of LV ejection fraction, only MA TDI S’ correlates with diastolic MA velocities as no correlation was identified between MAPSE and measures of LV diastole. Additional studies are now warranted to explore whether a reduced MA TDI S’ may affect the symptomatic profile or the overall prognosis of patients with LV diastolic dysfunction.

Annular dynamics after mitral valve repair with different prosthetic rings: A real-time three-dimensional transesophageal echocardiography study.

We assessed the effects of different types of prosthetic rings on mitral annular dynamics using real-time three-dimensional echocardiography (RT3DE). RT3DE was performed in 44 patients, including patients undergoing mitral annuloplasty using the Cosgrove-Edwards flexible band (Group A, n=10), the semi-rigid Sorin Memo 3D ring (Group B, n=17), the semi-rigid Edwards Physio II ring (Group C, n=7) and ten control subjects. Various annular diameters were measured throughout the cardiac cycle. We observed flexible anterior annulus motion in all of the groups except Group C. A flexible posterior annulus was only observed in Group B and the Control group. The mitral annular area changed during the cardiac cycle by 8.4±3.2, 6.3±2.0, 3.2±1.3, and 11.6±5.0% in Group A, Group B, Group C, and the Control group, respectively. The dynamic diastolic to systolic change in mitral annular diameters was lost in Group C, while it was maintained in Group A, and to a good degree in Group B. In comparison to the Control group, the mitral annulus shape was more ellipsoid in Group B and Group C, and more circular in Group A. Although mitral regurgitation was well controlled by all of the types of rings that were utilized in the present study, we demonstrated that the annulus motion and annulus shape differed according to the type of prosthetic ring that was used, which might provide important information for the selection of an appropriate prosthetic ring.

Automatic mitral annulus tracking in volumetric ultrasound using non-rigid image registration.

Analysis of mitral annular dynamics plays an important role in the diagnosis and selection of optimal valve repair strategies, but remains cumbersome and time-consuming if performed manually. In this paper we propose non-rigid image registration to automatically track the annulus in 3D ultrasound images for both normal and pathological valves, and compare the performance against manual tracing. Relevant clinical properties such as annular area, circumference and excursion could be extracted reliably by the tracking algorithm. The root-mean-square error, calculated as the difference between the manually traced landmarks (18 in total) and the automatic tracking, was 1.96 ± 0.46 mm over 10 valves (5 healthy and 5 diseased) which is within the clinically acceptable error range.

Mitral Annular Dynamics in Mitral Annular Calcification: A Three-Dimensional Imaging Study

The mitral annulus displays complex conformational changes during the cardiac cycle that can now be quantified by three-dimensional echocardiography. Mitral annular calcification (MAC) is increasingly encountered, but its structural and dynamic consequences are largely unexplored. The objective of this study was to describe alterations in mitral annular dimensions and dynamics in patients with MAC. Transthoracic three-dimensional echocardiography was performed in 43 subjects with MAC and 36 age- and sex-matched normal control subjects. Mitral annular dimensions were quantified, using dedicated software, at six time points (three diastolic, three systolic) during the cardiac cycle. In diastole, the calcified annulus was larger and flatter than normal, with increased anteroposterior diameter (29.4 ± 0.6 vs 27.8 ± 0.6 mm, P = .046), reduced height (2.8 ± 0.2 vs 3.6 ± 0.2 mm, P = .006), and decreased saddle shape (8.9 ± 0.6% vs 11.4 ± 0.6%, P = .005). In systole, patients with MAC had greater annular area at all time points (P < .05 for each) compared with control subjects, because of reduced contraction along the anteroposterior diameter (P < .001). Saddle shape increased in early systole (from 10.5% to 13.5%, P = .04) in control subjects but not in those with MAC (P = NS). Valvular alterations were also noted; although mitral valve tent length decreased during systole in both groups, decreases were less in patients with MAC (P < .05 for mid- and late systole). For certain parameters (e.g., annular area), changes were confined largely to those patients with moderate to severe MAC (P = .006 vs control subjects, but nonsignificant for patients with mild MAC). Quantitative three-dimensional echocardiography provides new insights into the dynamic consequences of MAC. This imaging technique demonstrates that the mitral annulus is not made smaller by calcification. However, there is loss of annular contraction, particularly along the anteroposterior diameter, and loss of early systolic folding along the intercommissural diameter. Associated valvular alterations include smaller than usual declines in tenting during systole. These quantitative three-dimensional echocardiographic data provide new insights into the dynamic physiology of the calcified mitral annulus.

3 D assessment of mitral annular dynamics in mitral stenosis: A novel parameter to assess stenosis severity

3 D assessment of mitral annular dynamics in mitral stenosis: A novel parameter to assess stenosis severity

Mitral valve repair: an echocardiographic review: Part 2.

Echocardiographic imaging of the mitral valve before and immediately after repair is crucial to the immediate and long-term outcome. Prior to mitral valve repair, echocardiographic imaging helps determine the feasibility and method of repair. After the repair, echocardiographic imaging displays the new baseline anatomy, assesses function, and determines whether or not further management is necessary. Three-dimensional imaging has improved the assessment of the mitral valve and facilitates communication with the surgeon by providing the surgeon with an image that he/she might see upon opening up the atrium. Further advancements in imaging will continue to improve the understanding of the function and dysfunction of the mitral valve both before and after repair. This information will improve treatment options, timing of invasive therapies, and advancements of repair techniques to yield better short- and long-term patient outcomes. The purpose of this review was to connect the echocardiographic evaluation with the surgical procedure. Bridging the pre- and post-CPB imaging with the surgical procedure allows a greater understanding of mitral valve repair.

Normal mitral annulus dynamics and its relationships with left ventricular and left atrial function.

Mitral annulus (MA) geometry and dynamics are crucial for preserving normal mitral valve (MV) function. Static reference values for MA parameters have been reported, but the normal MA dynamics during the entire cardiac cycle remains controversial. MV full-volume datasets were obtained by three-dimensional transthoracic echocardiography from 50 healthy volunteers (18-74 years; 31 men) to assess MA changes in size and shape during entire cardiac cycle. Using simultaneous multiplanar review, projected MA area (MAA) and circumference (MAC), antero-posterior (AP) and anterolateral-posteromedial (ALPM) diameters, and sphericity index (SphI) were obtained at: mitral valve closure (MVC), mid- and end-systole (ES), early- (EDF) and late-diastolic filling, and end-diastole. MAA and AP diameter were the most "active" parameters, changing in all reference frames (p < 0.001). MAA and AP diameter started to contract before MVC (during the left atrial contraction), reaching their minimum at MVC. Maximum MAA occurred at ES, while maximum AP diameter and SphI occurred at EDF. MAA fractional shortening was 35 ± 10 %. AP diameter change was 25 ± 10 %. MAC, ALPM and SphI showed similar patterns during left ventricular (LV) systole, and remained unchanged during diastole. Fractional change was 35 ± 10 % for MAC, and 13 ± 8 % for ALPM diameter. Our study provides the normal dynamics of the MA during the entire cardiac cycle. It reveals "pre-systolic" contraction of the MA, related to left atrial (LA) contraction, and minimal MAA during early LV systole. Therefore, the normal MA dynamics relates to a "physiologic LA-LV coupling", and a complete MA contraction requires both and properly timed LA and LV systole.

In-Vivo Analysis of Selectively Flexible Mitral Annuloplasty Rings Using Three-Dimensional Echocardiography

Selectively flexible rings, Colvin-Galloway (CG) Future and Carpentier-Edwards (CE) Physio II, are used for annuloplasty during mitral valve repair to facilitate dynamic annular motion while preventing annular dilation. In this study, we assessed the extent and nature of the flexibility of these rings invivo, which has not been objectively demonstrated. Three-dimensional transesophageal echocardiography was used intraoperatively to acquire data regarding dynamic motion of mitral annuli and annuloplasty rings in 33 patients undergoing mitral repair (15 CG Future and 18 CE Physio II) and in 15 control patients. Data were analyzed to assess the dynamic changes in annular geometry after implantation of selectively flexible rings. After annuloplasty, there was an immediate and significant decrease in annular displacement (p < 0.001) and annular displacement velocity (p < 0.01). Dynamic change in multiple variables including anteroposterior diameter (p < 0.001) and annular area (p < 0.001) was also significantly depressed. In comparison with normal mitral valves, partially flexible rings allowed limited dynamic motion: percentage changes in anteroposterior diameter (p < 0.001), anterolateral posteromedial diameter (p < 0.001), and total circumference (p < 0.001) were significantly lower. Compared with each other, the two rings resulted in similar changes in anterior annulus length (p= 0.93), posterior annular length (p= 0.82), and annular area (p= 0.31). Mitral annular dynamics were uniformly depressed after implantation of these rings. Selective flexibility could not be demonstrated invivo using echocardiographic data.

Real‐Time 3‐Dimensional Dynamics of Functional Mitral Regurgitation: A Prospective Quantitative and Mechanistic Study

BackgroundThree‐dimensional transthoracic echocardiography (3D‐TTE) with dedicated software permits quantification of mitral annulus dynamics and papillary muscle motion throughout the cardiac cycle.Methods and ResultsMitral apparatus 3D‐TTE was acquired in controls (n=42), patients with left ventricle dysfunction and functional mitral regurgitation (LVD‐FMR; n=43) or without FMR (LVD‐noMR, n=35). Annulus in both normal and LVD‐noMR subjects displayed saddle shape accentuation in early‐systole (ratio of height to intercommissural diameter, 10.6±3.7 to 13.5±4.0 in normal and 9.1±4.3 to 12.6±3.6 in LVD‐noMR; P<0.001 for diastole to early‐systole motion, P=NS between those groups). In contrast, saddle shape was unchanged from diastole in FMR patients (10.0±6.4 to 8.0±5.2; P=NS, P<0.05 compared to both other groups). Papillary tips moved symmetrically towards to the midanterior annulus in control and LVD‐noMR subjects, maintaining constant ratio of the distances between both tips to midannulus (PtAR) throughout systole. In LVD‐FMR patients midsystolic posterior papillary tip to anterior annulus distance was increased, resulting in higher PtAR (P=0.05 compared to both other groups). Mechanisms of early‐ and midsystolic FMR differed between different etiologies of LV dysfunction. In patients with anterior MI and global dysfunction annular function and dilatation were the dominant parameters, while papillary muscle motion was the predominant determinant of FMR in patients with inferior MI.ConclusionsInadequate early‐systolic annular contraction and saddle‐shape accentuation in patients with impaired LV contribute to early–mitral incompetency. Asymmetric papillary tip movement towards the midanterior annulus is a major determinant of mid‐ and late‐systolic functional mitral regurgitation.

Three-Dimensional Echocardiographic Analysis of Mitral Annular Dynamics

Background— Proponents of flexible annuloplasty rings have hypothesized that such devices maintain annular dynamics. This hypothesis is based on the supposition that annular motion is relatively normal in patients undergoing mitral valve repair. We hypothesized that mitral annular dynamics are impaired in ischemic mitral regurgitation and myxomatous mitral regurgitation. Methods and Results— A Philips iE33 echocardiographic module and X7–2t probe were used to acquire full-volume real-time 3-dimensional transesophageal echocardiography loops in 11 normal subjects, 11 patients with ischemic mitral regurgitation and 11 patients with myxomatous mitral regurgitation. Image analysis was performed using Tomtec Image Arena, 4D-MV Assessment, 2.1 (Munich, Germany). A midsystolic frame was selected for the initiation of annular tracking using the semiautomated program. Continuous parameters were normalized in time to provide for uniform systolic and diastolic periods. Both ischemic mitral regurgitation (9.98±155 cm 2 ) and myxomatous mitral regurgitation annuli (13.29±3.05 cm 2 ) were larger in area than normal annuli (7.95±1.40 cm 2 ) at midsystole. In general, ischemic mitral regurgitation annuli were less dynamic than controls. In myxomatous mitral regurgitation, annular dynamics were also markedly abnormal with the mitral annulus dilating rapidly in early systole in response to rising ventricular pressure. Conclusions— In both ischemic mitral regurgitation and myxomatous mitral regurgitation, annular dynamics and anatomy are abnormal. Flexible annuloplasty devices used in mitral valve repair are, therefore, unlikely to result in either normal annular dynamics or normal anatomy.

Mitral Annulus Dynamics Early after Valve Repair: Preliminary Observations of the Effect of Resectional Versus Non-Resectional Approaches

Mitral repair is recommended for patients with significant organic mitral regurgitation (MR). The nonresectional dynamic mitral valve repair (NVR) method involves a complete flexible ring and artificial chordal insertion but without leaflet resection or annular plication. The aim of this study was to compare changes in mitral annular structure and function after the NVR technique with those after a resectional mitral valve repair (RVR) method, which involves leaflet resection and annuloplasty with a partial flexible ring. Patients with organic severe MR undergoing mitral valve repair with either technique underwent three-dimensional transesophageal echocardiography before and after surgery. The mitral annulus was tracked offline and measured throughout the cardiac cycle. Mitral leaflet mobility was also measured. Fifteen patients underwent repair with NVR, and 13 underwent repair with RVR (age, 56 vs 61 years, respectively). Both operations reduced mitral annular area significantly (maximum area reduction, from 18.5 ± 4.6 to 6.6 ± 1.7 cm(2) and from 20.1 ± 4.8 to 6 ± 1.5 cm(2) with the NVR and RVR techniques, respectively; P < .001). In contrast to RVR, patients who underwent NVR maintained dynamic changes in mitral annular area, circumference, and anterior-posterior diameter during the cardiac cycle. Mitral leaflet mobility was reduced with both techniques, but posterior leaflet mobility was restricted with RVR. The size of the mitral annulus is reduced after repair with either surgical approach. Compared with resectional valve repair, more dynamic changes in the structure of the mitral annulus are maintained during the cardiac cycle with the NVR technique early postoperatively, along with more preserved motion of the posterior leaflet.

Characterization of Mitral Valve Annular Dynamics in the Beating Heart

The objective of this study is to establish a mathematical characterization of the mitral valve annulus that allows a precise qualitative and quantitative assessment of annular dynamics in the beating heart. We define annular geometry through 16 miniature markers sewn onto the annuli of 55 sheep. Using biplane videofluoroscopy, we record marker coordinates in vivo. By approximating these 16 marker coordinates through piecewise cubic splines, we generate a smooth mathematical representation of the 55 mitral annuli. We time-align these 55 annulus representations with respect to characteristic hemodynamic time points to generate an averaged baseline annulus representation. To characterize annular physiology, we extract classical clinical metrics of annular form and function throughout the cardiac cycle. To characterize annular dynamics, we calculate displacements, strains, and curvature from the discrete mathematical representations. To illustrate potential future applications of this approach, we create rapid prototypes of the averaged mitral annulus at characteristic hemodynamic time points. In summary, this study introduces a novel mathematical model that allows us to identify temporal, regional, and inter-subject variations of clinical and mechanical metrics that characterize mitral annular form and function. Ultimately, this model can serve as a valuable tool to optimize both surgical and interventional approaches that aim at restoring mitral valve competence.

The Mitral Valve by Three-Dimensional Echocardiography

A comprehensive evaluation of patients with mitral valve disease must include an echocardiographic examination of the mitral valve apparatus and resultant hemodynamic changes due to mitral pathology. Three-dimensional echocardiography has impacted on the diagnosis of mitral valve prolapse but has mostly existed in a research realm. After decades of development, three-dimensional echocardiography is now easily performed and readily incorporated in the assessment of mitral valve disease in daily clinical practice. Unique anatomic views of the mitral valve, accurate quantitative assessment of the mitral valve orifice area, and delineation of segmental prolapse are several advantages of three-dimensional echocardiography. Moreover, there is a wealth of data that can be derived from a three-dimensional volume, enabling more detailed analysis of mitral valve apparatus and valve annular dynamics. This review highlights current applications of three-dimensional echocardiography in the routine evaluation of mitral valve disease.

Effect of Biodegradable Ring on Dimensions and Dynamics of Mitral Annulus

Effect of Biodegradable Ring on Dimensions and Dynamics of Mitral Annulus

Clinical Summaries

Clinical Summaries

Releasable annuloplasty ring insertion — a novel experimental implantation model☆

Experimental testing of annuloplasty ring (AR) effects requires a control group if the AR is implanted conventionally. Our goal was to develop a reversible AR insertion method that allows for beating heart assessment with and without an AR, providing the ability to evaluate the effects of an AR in the same animal (internal control). We tested the feasibility of this technique in an in vivo ovine model using four-dimensional (4-D) radiopaque marker tracking. Before the operation, a rigid AR (Edwards Geoform, Edwards Lifesciences, Irvine, CA, USA) was prepared by stitching the middle parts of eight double-armed sutures evenly spaced through the ring fabric using a Spring Eye needle. The resulting loops were 'locked' with polypropylene sutures. In addition, two drawstring sutures were attached to the AR. Using cardiopulmonary bypass and cardioplegic arrest, 12 adult sheep had 16 radiopaque markers sewn to the mitral annulus. The AR was implanted by stitching the eight sutures equidistantly in a perpendicular direction through the mitral annulus. The sheep were transferred to the catheterisation laboratory and 4-D marker coordinates were obtained using biplane videofluoroscopy (60 Hz) with the AR inserted (Geo-AR). The locking sutures were then released, the AR was pulled up to the atrial roof using the drawstring sutures and another dataset was acquired (control). Maximum and minimum mitral annular areas (MAA(max), MAA(min)) during the cardiac cycle were derived from implanted markers. Data are provided from one representative animal. AR insertion and release were uneventful in all animals. Whereas the mitral annulus was dynamic in the control state (MAA(max): 9.0 cm(2), MAA(min): 7.8 cm(2)), mitral annular dynamics were abolished in the Geo-AR case (MAA(max): 6.2 cm(2), MAA(min): 6.0 cm(2)). This novel releasable AR implantation method is feasible and permits in vivo assessment of AR effects in the same heart. The new technique should facilitate experimental AR testing and promote the development of ARs based on physical criteria.

Presystolic mitral annular septal–lateral shortening is independent from left atrial and left ventricular contraction during acute volume depletion☆☆☆

The mitral annulus (MA) is a dynamic structure that joins the left atrium (LA) and left ventricle (LV), but it is unknown whether MA motion is coupled to the LA or the LV or neither of the two. Since a well orchestrated coordination of LA, MA and LV septal-lateral (S-L) dynamics is essential for efficient valve closure, we assessed their functional coupling in an experimental ovine model. To assess the coupling under a wide range of physiological conditions, data were acquired in normal and acutely volume depleted hearts. In 10 sheep, radiopaque markers were placed in LA, MA and LV base (LVbase). Twelve weeks postoperatively, 4-D marker coordinates were obtained by stereo videofluoroscopy (60 frames/s) before (CTRL) and during acute inferior vena caval occlusion (VCO). Septal-lateral dimensions were calculated as distances between corresponding marker pairs in the LA, MA and LVbase 5 frames before end-diastole (ED-84 ms) and at end-diastole. Dynamics during late diastole are described as changes from ED-84 ms versus end-diastole. To study the functional coupling between LA, MA and LVbase we calculated slopes during late diastole from simple linear regressions on an animal-by-animal basis. During late diastole in CTRL, the LA and MA both shortened along the S-L dimension (32.9 +/- 6.6 mm vs 31.0 +/- 5.5 mm, p = 0.026 and 27.3 +/- 3.7 mm vs 24.6 +/- 4.1 mm, p = 0.005, respectively) whereas the LVbase lengthened (56.2 +/- 9.3 mm vs 57.3 +/- 9.3 mm, p = 0.012). VCO abolished septal-lateral dynamics of LA and LVbase during late diastole (27.8 +/- 4.3 mm vs 27.4 +/- 3.9 mm, p = 0.155 and 49.4 +/- 7.7 mm vs 49.5 +/- 7.5 mm, p = 0.752, respectively) while the MA still shortened (19.0 +/- 2.9 vs 18.0 +/- 2.8, p = 0.042). Under CTRL conditions LA dynamics were linearly dependent from MA dynamics (average coefficient 0.57, p = 0.001), suggesting that LA and MA are functionally coupled. With acute volume depletion, MA dynamics were linearly independent from both, LA and LV (average coefficient 0.28, p = 0.159 and 0.58, p = 0.192, respectively). Whereas MA and LA dynamics are coupled during late diastole in hearts with normal LV volumes, presystolic mitral annular septal-lateral shortening is independent from LA and LV dynamics with acute volume depletion. A better understanding of mitral annular dynamics and their functional coupling may help improve mitral valve repair strategies.

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

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. 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. 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. 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.

Influence of Ventricular Pressure Drop on Mitral Annulus Dynamics Through the Process of Vortex Ring Formation

Several studies have suggested that the mitral annulus displacement and velocity in early diastole can be used as indicators of diastolic performance. The peak velocity of the mitral annulus away from the LV apex during early diastole, which indicates the rate of longitudinal expansion of the LV, is reduced in patients with impaired diastolic relaxation. With the intention of relating the trans-mitral flow to mitral annulus plane dynamics, we measured mitral annulus recoil force for different valve sizes, while applying an exponential pressure drop in a simplified model of the ventricle. The temporal changes in diameter of the valve during rapid filling phase were also considered. The process of ventricular vortex formation was studied together with the measurement of mitral annulus recoil force within different pressure drop conditions. Matching the vorticity contour plots with the recoil force measurements resulted in the fact that the magnitude of recoil is maximal once the vortex ring is about to pinch off, regardless of the valve size or the characteristics of ventricular pressure drop. This study showed that the mitral annulus recoil is maximal once occurs at the vortex formation time ranging from 3.5 to 4.5. It was also shown that the presence of leaflets would dissipate the annulus recoil force.