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

Relation of Mitral Annulus and Left Atrial Dysfunction to the Severity of Functional Mitral Regurgitation in Patients with Dilated Cardiomyopathy

METHODS

56 patients (58 ± 17 years, 42 men) with DCM and FMR and 52 controls, prospectively enrolled, underwent 3DTTE dedicated for mitral valve (MV), LA, and left ventricle (LV) quantitative analysis.

RESULTS

Patients with FMR vs. controls presented increased MA size and sphericity during the entire systole, whereas MA fractional area change (MAFAC) and MA displacement were decreased (15 ± 5 vs. 28 ± 5%; and 5 ± 3 vs. 10 ± 2 mm, p < 0.001). In patients with moderate/severe FMR, MA diameters correlated with PISA radius, EROA, and regurgitant volume (Rvol), as also did the MA area (with PISA radius, EROA, and Rvol: r = 0.48, r = 0.58, and r = 0.47, p < 0.05). MAFAC correlated inversely with EROA and Rvol (r = -0.32 and r = -0.35, p < 0.05), with both active and total LA emptying fractions and with LV ejection fraction as well. In a stepwise multivariate regression model, decreased MAFAC and increased LA volume independently predicted patients with severe FMR.

CONCLUSIONS

Patients with DCM and FMR have MA geometry remodeling and contractile dysfunction, correlated with the severity of FMR. MA contractile dysfunction correlated with both LA and left LV pumps dysfunctions and predicted patients with severe FMR. Our results provide new insights that might help with better selection of patients for MV transcatheter procedures.

Cardiac Magnetic Resonance Analysis of Mitral Annular Dynamics after Mitral Valve Repair

OBJECTIVES

The aim of this study was to analyze mitral annulus (MA) dynamics using cardiac magnetic resonance (CMR) in patients with degenerative mitral insufficiency who underwent mitral valve repair (MVR).

METHODS

Mitral valve imaging was performed by CMR in twenty-nine patients with degenerative mitral insufficiency who underwent MVR between July 2014 and August 2016, with quadrangular resection of the posterior leaflet without ring annuloplasty. They were prospectively followed up from the preoperative period up to 2 years postoperatively.

RESULTS

We observed a significant reduction in all measurements of the MA after surgery. The mean systolic circumference of the MA was reduced from 13.28±1.95 cm to 11.50±1.59 cm, and the diastolic circumference was reduced from 12.51±2.01 cm to 10.66±2.09 cm in the immediate postoperative period, measures that remained stable 2 years after MVR (p<0.001). The mean maximum area of the MA was significantly reduced from 14.34±4.03 to 10.45±3.17 cm2 when comparing the immediate postoperative period and the 2 year follow-up (p<0.001). The same occurred with the mean minimum area of the MA, which was reduced from 12.53±3.68 cm2 to 9.23±2.84 cm2 in the same period, and this reduction was greater in the antero-posterior diameter than in the mid-lateral diameter. The mobility of the MA was preserved after surgery, ranging between 19.6% and 25.7% at 2-year follow-up.

CONCLUSION

We observed a significant reduction in the MA size after MVR, with preservation of the MA mobility at the 2-year follow-up.

Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography

Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE.Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes).Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement.

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.

Mitral valve geometry in paediatric rheumatic mitral regurgitation

Rheumatic mitral valve disease is associated with valvulitis and valvular regurgitation; however, the effect of the rheumatic process on the mitral valve geometry and function is not well understood. To assess mitral valve annulus remodelling in rheumatic mitral valve disease, 16 subjects aged 6-15 years with rheumatic mitral valve regurgitation [MR] [6 mild or moderate (Group 1), 10 severe (Group 2)] and 7 age- and body size-matched normal controls with adequate trans-thoracic echocardiograms were recruited. None of the patients had undergone surgical intervention and none had more than mild aortic regurgitation. None of the patients had mitral stenosis. 3D mitral valve geometry was assessed using a Tomtec system. The non-planar angle was increased in all subjects during early (control 147° ± 10, Group 1 168° ± 9, Group 2 166° ± 10; p < 0.05) and late systole (control 149° ± 12, Group 1 162° ± 10, Group 2 164° ± 6; p < 0.05), indicating loss of saddle shape. 2D annular area increased in Group 2 (control 397 ± 48 mm(2)/m(2) vs Group 2 739 ± 207, p < 0.05) with no significant change in annular perimeter indicating leaflet effacement. Mitral valve area correlated with left ventricular size (p < 0.001, r (2) = 0.74). There was no significant change in valve area and perimeter between early and late systole. Remodelling of the mitral valve apparatus in childhood rheumatic heart disease results in abnormal annular geometry. The mitral valve loses its saddle shape regardless of the severity of MR. This may be a consequence of inflammation on the fibrous trigones and surrounding annulus. In contrast, annular area enlargement occurs as a result of leaflet effacement and relates to MR severity and LV size.

Another multidisciplinary look at ischemic mitral regurgitation

Ischemic mitral regurgitation (IMR) continues to challenge surgeons and scientists alike. This vexing clinical entity frequently complicates myocardial infarction and carries a poor prognosis both in the setting of coronary disease and idiopathic dilated cardiomyopathy. Ischemic mitral regurgitation encompasses a difficult patient population that is characterized by high operative mortality, poor long term outcomes, and frequent recurrent insufficiency after standard surgical repair. Yet optimal surgical repair and improved clinical outcomes can only be achieved with better knowledge of the pathophysiology of IMR which is still incompletely understood. The causative mechanism of IMR appears to lie in the annular and subvalvular frame of the valve rather than leaflet or chordal structure leading to such labels as "ischemic," "functional," "non-organic," and "cardiomyopathy associated" being applied in the clinical literature. Although ischemic mitral regurgitation is a prevailing clinical entity, it has not been consistently defined in the literature, contributing to considerable confusion and contradictory results of clinical studies. As the mechanisms of pathophysiology have been better elucidated, novel surgical and interventional strategies have been developed recently to provide better treatment for this difficult patient population. In this review, we undertake a multidisciplinary update of the pathophysiology, classification, and surgical and interventional treatment of ischemic mitral regurgitation in today's clinical practice.

Assessment of Mitral Valve Complex by Three-Dimensional Echocardiography: Therapeutic Strategy for Functional Mitral Regurgitation

The mitral valve complex is consisted of annulus, leaflets, chordae tendineae, papillary muscle (PMs) and surrounding left ventricle. Functional mitral regurgitation (MR) results from left ventricular remodeling such as dilatation or distortion, which displaces the PMs and then tethers the mitral leaflets, restricting leaflet coaptation. Undersized annuloplasty, which has been widely accepted as a simple and effective procedure for functional MR, sometimes worsens the tethering of posterior leaflet and induces recurrent MR. In order to overcome such problems, several additional procedures to the simple annuloplasty have been produced. Three dimensional echocardiography plays an essential role to understand the geometry of mitral valve complex and contributes greatly to decision making of the surgical strategy in functional MR and its postoperative assessment.

Mitral annular nonplanarity: correlation between annular height/commissural width ratio and the nonplanarity angle

OBJECTIVE

To compare two methods of mitral annular nonplanarity: the mathematically calculated annular height-to-commissural width ratio (AHCWR) and the echocardiographically derived nonplanarity angle.

DESIGN

Prospective.

SETTING

Tertiary care university hospital.

INTERVENTIONS

Three-dimensional transesophageal echocardiography.

PARTICIPANTS

Patients undergoing mitral valve surgery.

MEASUREMENTS AND MAIN RESULTS

Using 3-dimensional transesophageal echocardiography, volumetric datasets were acquired from 22 patients undergoing mitral valve surgery. The intraoperative nonplanarity angle was calculated with Mitral Valve Assessment software (Tomtec GmbH, Munich, Germany). Furthermore, the datasets acquired during 3-dimensional transesophageal echocardiography were exported to Matlab software (MathWorks, Natick, MA), which was used to calculate the AHCWR. The nonplanarity angle was seen to correlate favorably with the AHCWR (r = 0.70).

CONCLUSIONS

A favorable correlation was found between the nonplanarity angle and the AHCWR. This suggests that the nonplanarity angle can be used to assess mitral annular nonplanarity in a clinically feasible fashion.

RT-3D TEE: characteristics of mitral annulus using mitral valve quantification (MVQ) program

AIM

To evaluate the mitral annulus characteristics in significant mitral regurgitant lesions using mitral valve quantification (MVQ) program.

METHODS

We examined 117 patients (39 women), aged 18-86. Patients were separated into four subgroups: 35 patients with ischemic mitral regurgitation, 42 patients with isolated prolapse of the mitral valve, 12 patients with Barlow disease, and 28 healthy controls. Mitral annulus was examined in end-systole. The following parameters were assessed: anteroposterior and intercommissural diameter, perimeter of annulus, area of minimal surface spanning annulus and height of the mitral annulus. A new parameter--mitral annulus height index (height/circumference × 100) was introduced. Values of these parameters in subgroups with mitral pathology were compared with corresponding parameters of control group using Student t-test.

RESULTS

In subgroups with mitral pathology all parameters except mitral annulus height and mitral annulus height index were significantly higher than those in the control group. Mitral annulus height was significantly higher in Barlow disease, significantly lower in mitral prolapse group and comparable to normal controls in the ischemic regurgitation group. Mitral annulus height index was significantly higher in Barlow disease and significantly lower in patients with prolapse and ischemic regurgitation.

CONCLUSIONS

Barlow disease is characterized by dilation and vertical deformation of the mitral annulus (annulus height and height index increase). Prolapse of the mitral valve and ischemic regurgitation of mitral annulus involve dilation and flattening of the annulus (annulus height decreases in prolapse group significantly, in ischemic regurgitation nonsignificantly, while annulus height index decreases significantly in both subgroups).

Changes in mitral valve annular geometry after repair: saddle-shaped versus flat annuloplasty rings

BACKGROUND

Saddle-shaped annuloplasty rings are being increasingly used during mitral valve (MV) repair to conform the mitral annulus to a more nonplanar shape and possibly reduce leaflet stress. In this study utilizing three-dimensional transesophageal echocardiography we compared the effects of rigid flat rings with those of the saddle rings on the mitral annular geometry. Specifically we measured the changes in nonplanarity angle (NPA) before and after MV repair.

METHODS

Geometric analysis on 38 patients undergoing MV repair for myxomatous and ischemic mitral regurgitation with full flat rings (n = 18) and saddle rings (n = 18) were performed. The acquired three-dimensional volumetric data were analyzed utilizing the "Image Arena" software (TomTec GmBH, Munich, Germany). Specifically, the degree of change in the NPA was calculated and compared before and after repair for both types of rings.

RESULTS

Both types of annuloplasty rings resulted in significant changes in the geometric structure of the MV after repair. However, saddle rings lead to a decrease in the NPA (7% for ischemic and 8% for myxomatous MV repairs) (ie, made the annulus more nonplanar), whereas flat rings increased the NPA (7.9% for ischemic and 11.8% for myxomatous MV repairs) (ie, made the annulus less nonplanar); p value 0.001 or less.

CONCLUSIONS

Implantation of saddle-shaped rings during MV repair surgery is associated with augmentation of the nonplanar shape of the mitral annulus (ie, decreases NPA). This favorable change in the mitral annular geometry could possibly confer a structural advantage to MV repairs with the saddle rings.

Complete mapping of the tricuspid valve apparatus using three-dimensional sonomicrometry

OBJECTIVE

Many surgeons consider the tricuspid valve to be a second-class structure. Our objective was to determine the normal anatomy and dynamic characteristics of the tricuspid valve apparatus in vivo and to discern whether this would aid the design of a tricuspid valve annuloplasty ring model.

METHODS

Sixteen sonomicrometry crystals were placed around the tricuspid annulus, at the bases and tips of the papillary muscles, the free edges of the leaflets, and the right ventricular apex during cardiopulmonary bypass in 5 anesthetized York Hampshire pigs. Animals were studied after weaning of cardiopulmonary bypass on 10 cardiac cycles of normal hemodynamics.

RESULTS

Sonomicrometry array localizations demonstrate the multiplanar shape of the tricuspid annulus. The tricuspid annulus reaches its maximum area (97.9 ± 25.4 mm(2)) at the end of diastole and its minimum area (77.3 ± 22.5 mm(2)) at the end of systole, and increases again in early diastole. Papillary muscles shorten by 0.8 to 1.5 mm (11.2%) in systole, and chordae tendineae straighten by 0.8 to 1.7 mm (11.4%) in systole.

CONCLUSIONS

The shape of the tricuspid annulus is a multiplanar 3-dimensional one with its highest point at the anteroseptal commissure and its lowest point at the posteroseptal commissure, and the anteroposterior commissure is in a middle plane in between. The tricuspid annulus area reaches its maximum during diastole and its minimum during systole. The papillary muscles contract by the same amount of chordal straightening. The optimal tricuspid annuloplasty ring may be a multiplanar 3-dimensional one that mimics the normal tricuspid annulus.

Three-dimensional echocardiographic assessment of changes in mitral valve geometry after valve repair

BACKGROUND

Application of annuloplasty rings during mitral valve (MV) repair has been shown to significantly change the mitral annular geometry. Until recently, a comprehensive two-dimensional echocardiographic evaluation of annular geometric changes was difficult owing to its nonplanar orientation. In this study, an analysis of the three-dimensional intraoperative transesophageal echocardiographic evaluation of the MV annulus is presented before and immediately after repair.

METHODS

We performed three-dimensional geometric analysis on 75 patients undergoing MV repair during coronary artery bypass graft surgery for mitral regurgitation or myxomatous mitral valve disease. Geometric analysis of the MV was performed before and immediately after valve repair with full rings and annuloplasty bands. The acquired three-dimensional volumetric data were analyzed in the operating room. Specific measurements included annular diameter, leaflet lengths, the nonplanarity angle, and the circularity index. Before and after repair data were compared.

RESULTS

Complete echocardiographic assessment of the MV was feasible in 69 of 75 patients (92%) within 2 to 3 minutes of acquisition. Placement of full rings resulted in an increase in the nonplanarity angle or a less saddle shape of the native mitral annulus (137 +/- 14 versus 146 +/- 14; p = 0.002. By contrast, the nonplanarity angle did not change significantly after placement of partial rings.

CONCLUSIONS

Mitral annular nonplanarity can be assessed in the operating room. Application of full annuloplasty rings resulted in the mitral annulus becoming more planar. Partial annuloplasty bands did not significantly change the nonplanarity angle. Neither of the two types of rings restored the native annular planarity.

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.

Does the mitral annulus shrink or enlarge during systole? A real-time 3D echocardiography study

This study was conducted to explore the geometrical changes of the mitral annulus during systole. The 3D shape of the mitral annulus was reconstructed in 13 normal subjects who had normal structure of the mitral apparatus using real-time 3D echocardiography (RT3DE) and 3D computer software. The two orthogonal (antero-posterior and commissure-commissure) dimensions, the areas (2D projected and 3D surface) and the non-planarity of the mitral annulus were estimated during early, mid and late systole. We demonstrated that the MA had a "saddle shape" appearance and it consistently enlarged mainly in the antero-posterior direction from early to late systole with lessening of its non-planarity, as was determined by 3D reconstruction using RT3DE and 3D computer software.

A multiplanar three dimensional echocardiographic study of mitral valvar annular function in children with normal and regurgitant valves

INTRODUCTION

The mitral valvar complex is difficult to visualise accurately in only two dimensions. Three-dimensional echocardiography gives new insight into the dynamic changes of intra-cardiac structures during the cardiac cycle. The aim of this study was to study the mitral annulus in systole and diastole in normal children using three-dimensional echocardiography, and to analyse the effect of regurgitation on annular function.

MATERIALS AND METHODS

Three-dimensional echocardiographic datasets, acquired in 11 consecutive subjects with mitral regurgitation, and 20 normal subjects, were analysed offline using simultaneous multiplanar review.

RESULTS

The mitral valvar annular area decreased in diastole, and increased in systole, in both groups. The annulus in patients with mitral regurgitation is dilated compared to normal subjects, the systolic value for those with regurgitation having a mean of 6.79 plus or minus 2.55 centimetres2/metres2, and the diastolic value a mean of 5.01 plus or minus 1.78 centimetres2/metres2, as opposed to a systolic mean value of 5.28 centimetres2/metres2 plus or minus 1.68, p = 0.091, and diastolic mean value of 3.05 centimetres2/metres2 plus or minus 0.90, in normal subjects (p less than 0.0001). The proportional change in mitral valvar annular area from systole to diastole showed a trend towards being smaller in those with mitral regurgitation, although this did not reach significance (24.8% versus 41.13%, p equal to 0.249). Analysis of subgroups of patients with moderate or severe mitral regurgitation showed mitral excursion, expressed as percentage of left ventricular length, to be significantly less than in normal subjects, at 12.78 plus or minus 5.10% versus 15.84 plus or minus 4.23% (p equal to 0.012).

CONCLUSIONS

Mitral valvar annular area in children decreases in diastole, and increases in systole. In those with mitral regurgitation, the annulus is dilated and the dynamic annular function is depressed.

Description of regional mitral annular nonplanarity in healthy human subjects: a novel methodology

OBJECTIVE

Finite-element analysis demonstrates that the nonplanar shape of the mitral annulus diminishes mitral leaflet stress. It has therefore been postulated that repair with annuloplasty rings that maintain the nonplanar shape of the annulus could increase repair durability. Although the global nonplanarity of the mitral annulus has been adequately characterized, design of such a ring requires a quantitative description of regional annular geometry. By using real-time 3-dimensional echocardiography in conjunction with available image processing software, we developed a methodology for describing regional annular geometry and applied it to the characterization of the normal human mitral annulus.

METHODS

Five healthy volunteers underwent mitral valve imaging with real-time 3-dimensional echocardiography. Regional annular height was calculated at 36 evenly spaced intervals.

RESULTS

Maximal annular height/commissural width ratio was found to occur at the midpoint of the anterior annulus in all cases. These values averaged 26% +/- 3.1%, whereas those for the midposterior annulus averaged 18% +/- 3.0%. The average commissural width was 35.2 +/- 6.0 mm. Although substantial spatial heterogeneity was observed, regional annular height at a given rotational position was highly conserved among subjects when normalized to commissural width.

CONCLUSIONS

These quantitative imaging and analytic techniques demonstrate that the normal human mitral annulus is regionally heterogeneous in its nonplanarity, and they establish a means of describing annular geometry at a regional level. With wider application, these techniques may be used both to characterize pathologic annular geometry and to optimize the design of mitral valve annuloplasty devices.

Live/real-time three-dimensional transthoracic assessment of mitral regurgitation and mitral valve prolapse

Evaluation of the mitral valve requires appreciation of its complex geometry. To accurately guide surgical interventions and describe pathology, three-dimensional transthoracic echocardiography (TTE) is an immense improvement over the cumbersome mental reconstruction required by two-dimensional approaches. Here we describe real-time, three-dimensional transthoracic techniques for assessing mitral regurgitation and mitral valve prolapse.

Mitral Annular Remodeling with Varying Degrees and Mechanisms of Chronic Mitral Regurgitation

HYPOTHESES

Degree of mitral annular remodeling is directly associated with severity of chronic mitral regurgitation (MR). Mitral annular remodeling occurs in a symmetric fashion, regardless of MR severity. In addition to MR severity, MR mechanism plays a significant role in mitral annular remodeling.

BACKGROUND

Limited data exists on mitral annular remodeling in patients with MR. Identification of annular changes may be important in aiding surgical repair.

METHODS

Mitral annular dimensions (anteroposterior, intercommissural, surface area, and circumference) were measured in end systole and diastole using 3-dimensional reconstructive software in 83 patients: trace to no MR (23), mild MR (15), moderate MR (26), and severe MR (19). Annular sphericity indices were determined by dividing intercommissural by anteroposterior dimensions. Patients were further subgrouped by mechanism of MR.

RESULTS

With increasing MR severity, there was a corresponding increase in all annular measurements, most pronounced in the anteroposterior dimension, circumference, and area. Larger increases were seen in patients with prolapse/flail and dilated mechanisms. Furthermore, the mitral annulus became more circular (sphericity index approached 1.0) with increasing MR severity. Patients with prolapse/flail mechanisms exhibited normal left ventricular volumes despite significant annular enlargement.

CONCLUSIONS

Mitral annular remodeling is directly associated with MR severity and occurs in an asymmetric fashion, yet is not limited to one region of the annulus. Mechanism of MR plays a significant role in annular remodeling. Annular remodeling can occur independently of left ventricular remodeling.

Three-dimensional geometry of the tricuspid annulus in healthy subjects and in patients with functional tricuspid regurgitation: a real-time, 3-dimensional echocardiographic study

BACKGROUND

Most rings currently used for tricuspid valve annuloplasty are formed in a single plane, whereas the actual tricuspid annulus (TA) may have a nonplanar or 3-dimensional (3D) structure. The purpose of this study was therefore to investigate the 3D geometry of the TA in healthy subjects and in patients with functional tricuspid regurgitation (TR).

METHODS AND RESULTS

This study consisted of 15 healthy subjects and 16 patients with functional TR who had real-time 3D echocardiography. With our customized software, 8 points along the TA were determined with the rotated plane around the axis at 45 degrees intervals. The TA was traced during a cardiac cycle. The distance between diagonals connecting 2 points was measured. The height was defined as the distance from the plane determined by least-squares regression analysis at all 8 points. Both the maximum (7.5+/-2.1 versus 5.6+/-1.0 cm2/m2) and minimum (5.7+/-1.3 versus 3.9+/-0.8 cm2/m2) TA areas in patients with TR were larger than those in healthy subjects (both P<0.01). Healthy subjects had a nonplanar-shaped TA with homogeneous contraction. The posteroseptal portion was the lowest toward the apex from the right atrium, and the anteroseptal portion was the highest. In patients with functional TR, the TA was dilated in the septal to lateral direction, resulting in a more circular shape than in healthy subjects. A similar 3D pattern was observed in patients with TR, but it was more planar than that in healthy subjects.

CONCLUSIONS

Real-time 3D echocardiography showed a complicated 3D structure of the TA, which appeared to be different from the "saddle-shaped" mitral annulus, suggesting an annuloplasty for TR different from that for mitral regurgitation.

Real-time 3-dimensional echocardiographic imaging of congenital heart disease using matrix-array technology: freehand real-time scanning adds instant morphologic details not well delineated by conventional 2-dimensional imaging

OBJECTIVE

We sought to investigate whether real-time (RT) 3-dimensional echocardiography (RT3D) using matrix-array technology could resolve a specific morphologic detail that could not be well resolved during conventional 2-dimensional (2D)/Doppler echocardiographic imaging of congenital heart disease.

BACKGROUND

Although 2D echocardiography is currently the primary imaging modality of congenital heart disease, there are still some anatomic details that cannot be well delineated by that modality.

METHODS

In all, 70 patients underwent RT3D examination using matrix-array transducer. Applying the standard sweeping technique as for 2D imaging, freehand RT imaging was used for immediate feedback. The 2D examinations of the last 23 consecutive patients were used to validate the additional value of RT3D by 3 examiners blinded to the findings of RT3D.

RESULTS

The adequacy of 2D imaging to resolve the morphologic detail in question ranged from 30% to 70%, whereas RT3D imaging was considered successful in delineating the morphologic detail in 80% to 100% of patients instantly. The image resolution was superior or equivalent to that obtained by 2D imaging. Heart valves, septal defects, and volumetric valvular and vascular color flow morphologies were well delineated by RT3D.

CONCLUSION

Matrix-array RT3D is a significant breakthrough technology that allowed instant visualization of cardiac anatomic details that could not be well delineated by 2D imaging. Further improvements of some technical limitations should make RT3D matrix-array cardiac imaging a significant modality in the field of echocardiographic imaging of congenital cardiac anomalies.

Mitral annulus size links ventricular dilatation to functional mitral regurgitation

We compared the impact of annulus size and valve deformation (tethering) on mitral regurgitation in the animal dilated cardiomyopathy model, and assessed if acute left ventricular volume changes affect mitral annulus dimensions. We performed 3-dimensional echocardiography in 30 open-chest dogs with pacing-induced cardiomyopathy. Mitral annulus area was calculated from its two orthogonal diameters, whereas valve tethering was quantified by valve tenting area measurement. Mitral valve regurgitant volume showed the highest correlation with annulus area (r = 0.64, P < .001), left atrial volume (r = 0.40, P < .01), and left ventricular end-diastolic volume (r = 0.37, P < .01). Regurgitant volume showed poorer correlation with valve tethering in both septolateral and intercommissural planes (r = 0.35 and r = 0.31, P < .05 for both). Annulus dimensions correlated with acute changes of left ventricular end-diastolic volume (r = 0.68, P = .002). Mitral annulus dilation is the strongest predictor of functional mitral regurgitation in this animal dilated cardiomyopathy model.

Acute geometric changes of the mitral annulus after coronary occlusion: a real-time 3D echocardiographic study

We performed real-time 3D echocardiography in sixteen sheep to compare acute geometric changes in the mitral annulus after left anterior descending coronary artery (LAD, n=8) ligation and those after left circumflex coronary artery (LCX, n=8) ligation. The mitral regurgitation (MR) was quantified by regurgitant volume (RV) using the proximal isovelocity surface area method. The mitral annulus was reconstructed through the hinge points of the annulus traced on 9 rotational apical planes (angle increment=20 degrees). Mitral annular area (MAA) and the ratio of antero-posterior (AP) to commissure-commissure (CC) dimension of the annulus were calculated. Non-planar angle (NPA) representing non-planarity of the annulus was measured. After LCX occlusion, there were significant increases of the MAA during both early and late systole (p<0.01) with significant MR (RV: 30+/-14 mL), while there was neither a significant increase of MAA, nor a significant MR (RV: 4+/-5 mL) after LAD occlusion. AP/CC ratio (p<0.01) and NPA (p<0.01) also significantly increased after LCX occlusion during both early and late systole. The mitral annulus was significantly enlarged in the antero-posterior direction with significant decrease of non-planarity compared to LAD occlusion immediately after LCX occlusion.

Relationship of Mitral Annular Remodeling to Severity of Chronic Mitral Regurgitation

HYPOTHESES

(1) Mitral regurgitation (MR) severity is directly associated with mitral annular remodeling as evidenced by mitral annular enlargement. (2) Increasing severity of chronic MR will result in symmetric enlargement of the mitral annulus as measured by annular shape indices.

BACKGROUND

Limited data exist on mitral annular remodeling for patients with MR. Identification of annular changes may be important in aiding surgical repair.

METHODS

The mitral annulus was measured in several planes using transthoracic echocardiography in 173 patients: trace to no MR (34), mild MR (48), moderate MR (45), and severe MR (46). Patients were subgrouped by mechanism of MR and annular shape indices were determined.

RESULTS

With increasing MR severity, there was a corresponding symmetric increase in all systolic and diastolic measurements, but no significant differences in annular shape indices between subgroups by MR severity or by MR mechanism.

CONCLUSIONS

Mitral annular remodeling is symmetric, regardless of degree or mechanism of MR.

Electrical Conduction Disturbance Effects on Dynamic Changes of Functional Mitral Regurgitation

OBJECTIVES

The aim of this study was to investigate the relationship between dynamics of functional mitral regurgitation (MR) and the degree of electrical conduction disturbance, and to evaluate the impact of cardiac resynchronization therapy (CRT) on MR severity and its phasic pattern.

BACKGROUND

Mechanisms of phasic changes of functional MR, which may be determined by annulus dilation and tethering of the leaflet, remain unclear.

METHODS

Transthoracic two-dimensional echocardiography was performed in 60 patients with functional MR. A biventricular pacemaker was implanted in 19 patients. The mitral annulus area (MAA) and the tenting area (TA) were measured from apical views. The MR volume and fraction were assessed by the quantitative pulsed Doppler method. Instantaneous regurgitation flow rate was measured by proximal flow convergence method. A dynamic change in MR flow rate was evaluated by frame-by-frame analysis throughout systole.

RESULTS

A phasic pattern with two peaks at early- and late-systole and decrease in mid-systole was noticed in 57 patients. The early-systolic peak of MR was larger than the late-systolic peak (128.4 +/- 64.3 ml/s vs. 73.9 +/- 55.1 ml/s, p < 0.001). The ratio of flow rate at these two peaks correlated with QRS duration (r = 0.55, p < 0.001). Early-systolic flow rate reduced after CRT (143.9 +/- 60.8 ml/s to 90.7 +/- 54.1 ml/s, p < 0.05), but late-systolic flow rate did not (61.5 +/- 55.0 ml/s to 51.2 +/- 40.9 ml/s, p = NS). A similar pattern was observed for TA, whereas MAA did not change after CRT.

CONCLUSIONS

Biphasic pattern was found in functional MR, and the ratio of flow rate at two peaks correlated with QRS duration. The CRT decreased regurgitation flow volume by reducing early-systolic MR but not late-systolic MR, resulting in the change in phasic pattern of functional MR.