Interpapillary Muscle Distance Research Articles

Abstract 14766: Acute Impact of Transapical Ventricular Reshaping Device on Dilated Left Ventricle With Functional Mitral Regurgitation in Swine Model

Introduction: Functional mitral regurgitation (FMR) after myocardial infarction (MI) exacerbates morbidity and mortality. Correcting FMR plays a critical role in mitigating or reversing ventricular remodeling in MI patients with FMR. However, the COAPT trial demonstrated that FMR correction yields favorable results in smaller left ventricles (LVs) but not in severely dilated LVs. In this study, we evaluated the efficacy of a transapical device in MI swine model with FMR, which can perform papillary muscle approximation (PMA) and simultaneous reduction of LV volume. Methods: Yorkshire pig (n=15) were used in this study. MI was induced by percutaneous occlusion of the left circumflex artery, which caused LV dilatation and FMR by 3 months. The device was implanted through the LV apex to achieve PMA and LV reshaping until FMR was eliminated (Figure A). The immediate effects of the device implantation on the mitral valve and the LV were assessed using echocardiography and pressure-volume loops. Results: The device implantation decreased inter-papillary muscle distance from 24.5±3.8mm to 16.7±3.8mm (p<0.0001), and significantly reduced FMR. Coaptation length significantly increased from 3.4±0.7mm to 5.5±1.2mm (p<0.0001). End-diastolic volume decreased from 153±48ml to 117±33ml, a 23.5% reduction (p=0.0004). The end-systolic pressure-volume relationship and preload adjusted dP/dt max significantly increased after the device implant, indicating an improvement of LV contractility. There were no differences observed in Tau and end-diastolic pressure-volume relationship, depicting minimal acute impact on diastolic ventricular function after device implantation (Figure B and C). Conclusions: This transapical reshaping device effectively corrects FMR in very enlarged LVs, but also reduces systolic chamber wall stress by reducing the LV volume. An acute improvement in LV systolic function was observed, potentially indicating a therapeutic effect.

Mechanism of improvement in atrial functional mitral regurgitation after catheter ablation for atrial fibrillation: Three-dimensional analysis using multislice computed tomography.

Several factors associated with atrial functional mitral regurgitation development have been reported; however, geometric changes in the mitral apparatus after catheter ablation for atrial fibrillation have not been sufficiently investigated. This study aimed to clarify what determines improvements in atrial functional mitral regurgitation after sinus rhythm restoration in patients who underwent catheter ablation for atrial fibrillation by using multislice computed tomography. We analysed volumetric multislice computed tomography images of 44 atrial fibrillation patients with significant atrial functional mitral regurgitation (moderate or worse) before and after catheter ablation. We measured the three-dimensional geometry of the mitral apparatus including the mitral annular area and interpapillary muscle distance. We calculated the differences before and after catheter ablation (Δmitral annular area, Δinterpapillary muscle distance) and assessed mitral regurgitation severity based on the mitral regurgitant jet area and its changes before and after catheter ablation (Δjet area) using transthoracic echocardiography. After catheter ablation, the jet area was significantly decreased. The left ventricular ejection fraction was significantly increased and the left ventricular volume had a decreasing trend. The Δjet area was significantly correlated with the Δinterpapillary muscle distance (r = .43; p = .004). The Δinterpapillary muscle distance was the strongest determinant of improvements in atrial functional mitral regurgitation severity (p = .026). Decreased interpapillary muscle distance was strongly associated with improvements in atrial functional mitral regurgitation. Amelioration of left ventricular dysfunction by sinus rhythm restoration might be related to improvements in atrial functional mitral regurgitation after catheter ablation.

Left atrial geometry in an ovine ischemic mitral regurgitation model: implications for transcatheter mitral valve replacement devices with a left atrial anchoring mechanism

BackgroundTranscatheter mitral valve replacement (TMVR) is a challenging, but promising minimally invasive treatment option for patients with mitral valve disease. Depending on the anchoring mechanism, complications such as mitral leaflet or chordal disruption, aortic valve disruption or left ventricular outflow tract obstruction may occur. Supra-annular devices only anchor at the left atrial (LA) level with a low risk of these complications. For development of transcatheter valves based on LA anchoring, animal feasibility studies are required. In this study we sought to describe LA systolic and diastolic geometry in an ovine ischemic mitral regurgitation (IMR) model using magnetic resonance imaging (MRI) and echocardiography in order to facilitate future research focusing on TMVR device development for (I)MR with LA anchoring mechanisms.MethodsA group of 10 adult male Dorsett sheep underwent a left lateral thoracotomy. Posterolateral myocardial infarction was created by ligation of the left circumflex coronary artery, the obtuse marginal and diagonal branches. MRI and echocardiography were performed at baseline and 8 weeks after myocardial infarction (MI).ResultsSix animals survived to 8 weeks follow-up. All animals had grade 2 + or higher IMR 8 weeks post-MI. All LA geometric parameters did not change significantly 8 weeks post-MI compared to baseline. Diastolic and systolic interpapillary muscle distance increased significantly 8 weeks post-MI.ConclusionsSystolic and diastolic LA geometry do not change significantly in the presence of grade 2 + or higher IMR 8 weeks post-MI. These findings help facilitate future tailored TMVR device development with LA anchoring mechanisms.

Left ventricular remodeling after mitral valve repair and papillary muscle approximation.

Mitral valve repair with papillary muscle approximation (MVr-PMA) for severe secondary mitral regurgitation (MR) decreases MR recurrence compared with MVr alone. This study assessed the effects of MVr-PMA on left ventricular (LV) remodeling and shape, systolic function and strain mechanics. Forty-eight patients who underwent MVr-PMA for severe secondary MR and had follow-up echocardiograms available for review were identified. Student's t-test, linear regression modeling, and receiver-operating characteristic curves were used in the statistical analyses. Median follow-up time was 14.9 months. MVr-PMA was associated with significant LV reverse remodeling with a smaller LV end-diastolic diameter, Systolic Sphericity Index, and interpapillary muscle distance at follow-up. Nine patients (18.8%) experienced moderate recurrent MR. When compared to recurrent MR patients at follow-up, those with durable MVr-PMA had a greater LV ejection fraction (32.8 vs. 22.0%, P=0.03), a smaller end-diastolic diameter (59.6 vs. 67.3 mm, P=0.03), Systolic Sphericity Index (0.35 vs. 0.47, P=0.03), and end-systolic interpapillary muscle distance (16.3 vs. 21.1 mm, P=0.03). A durable MVr-PMA also resulted in stable global longitudinal strain when compared with pre-operative values, while the recurrent MR group experienced a further decline (no recurrent MR: -8.4 vs. -7.5%; recurrent MR: -8.2 vs. -5.4%; P<0.05). A pre-operative LV end-diastolic diameter ≥ 64 mm was a discriminative predictor of MR recurrence (sensitivity=100%, specificity=51%, AUC=0.756, P=0.02). A durable MVr-PMA confers improved LV geometry and function, and stable LV mechanics. The extent of baseline LV remodeling identifies patients at risk for recurrent MR.

Annular and subvalvular dynamics after extracellular matrix mitral tube graft implantation in pigs.

Entire mitral valve reconstruction with an extracellular matrix tube graft is a potential candidate to overcome the current limitations of mechanical and bioprosthetic valves. However, clinical data have raised concern with respect to patch failure. The aim of our study was to evaluate the impact of extracellular matrix mitral tube graft implantation on mitral annular and subvalvular regional dynamics in pigs. A modified tube graft design made of 2-ply extracellular matrix was used (CorMatrix®; Cardiovascular Inc., Alpharetta, GA, USA). The reconstructions were performed in an acute 80-kg porcine model (N = 8), where each pig acted as its own control. Haemodynamics were assessed with Mikro-Tip pressure catheters and mitral annular and subvalvular geometry and dynamics with sonomicrometry. Catheter-based peak left atrial pressure and pressure difference across the mitral and aortic valves in the reconstructions were comparable to the values seen in the native mitral valves. Also comparable were maximum mitral annular area (755 ± 100 mm2), maximum septal-lateral distance (29.7 ± 1.7 mm), maximum commissure-commissure distance (35.0 ± 3.4 mm), end-systolic annular height-to-commissural width ratio (10.2 ± 1.0%) and end-diastolic interpapillary muscle distance (27.7 ± 3.3 mm). Systolic expansion of the mitral annulus was, however, observed after reconstruction. The reconstructed mitral valves were fully functional without regurgitation, obstruction or stenosis. The reconstructed mitral annular and subvalvular geometry and subvalvular dynamics were found in the same range to those in the native mitral valve. A regional annular ballooning effect occurred that might predispose to patch failure. However, the greatest risk was found at the papillary muscle attachments.

Left ventricle and mitral valve reverse remodeling in response to cardiac resynchronization therapy in nonischemic cardiomyopathy.

Cardiac resynchronization therapy (CRT) improves left heart geometry and function in nonischemic cardiomyopathy (NICMP). We aimed to detail the effects of CRT on left ventricular (LV) and mitral valve (MV) remodeling using 2-dimensional transthoracic echocardiography. Forty-five consecutive patients with NICMP who underwent CRT implantation between 2009 and 2012, and had pre-CRT and follow-up echocardiograms available, were included. Paired t test, linear and logistic regression, and Kaplan-Meier survival analyses were used for statistical assessment. The mean age and QRS duration were 60years and 157ms, respectively, and 13 (28.9%) were female. At a mean follow-up of 3years, there were 22 (48.9%) "CRT responders" (≥15% reduction in LV end-systolic volume index [LVESVi]). Significant improvements were observed in LV ejection fraction (26.3% vs 34.3%) and LVESVi (87.7 vs 71.1mL/m2 ), as well as mitral regurgitation vena contracta width, MV tenting height and area, and end-systolic interpapillary muscle distance. Five-year actuarial survival was 87.5%. Multivariate regression analyses revealed the pre-CRT LVESVi (β=0.52), and MV coaptation length (β=-0.34) and septolateral annular diameter (β=0.25) as good correlates of follow-up LVESVi. Variables associated with CRT response were pre-CRT MV coaptation length (OR 1.75, 95% CI 1.0-3.1) and posterior leaflet tethering angle (OR 1.07, 95% CI 1.0-1.14), irrespective of baseline QRS morphology and duration (all P<.05). Cardiac resynchronization therapy improves LV and MV geometry and function in half of patients with NICMP, which is paralleled by decreased mitral regurgitation severity. The extent of pre-CRT LV remodeling and MV tethering are associated with CRT response.

Effect of Edge-to-Edge Mitral Valve Repair on Chordal Strain: Fluid-Structure Interaction Simulations.

Edge-to-edge repair for mitral valve regurgitation is being increasingly performed in high-surgical risk patients using minimally invasive mitral clipping devices. Known procedural complications include chordal rupture and mitral leaflet perforation. Hence, it is important to quantitatively evaluate the effect of edge-to-edge repair on chordal integrity. in this study, we employ a computational mitral valve model to simulate functional mitral regurgitation (FMR) by creating papillary muscle displacement. Edge-to-edge repair is then modeled by simulated coaptation of the mid portion of the mitral leaflets. in the setting of simulated FMR, edge-to-edge repair was shown to sustain low regurgitant orifice area, until a two fold increase in the inter-papillary muscle distance as compared to the normal mitral valve. Strain in the chordae was evaluated near the papillary muscles and the leaflets. Following edge-to-edge repair, strain near the papillary muscles did not significantly change relative to the unrepaired valve, while strain near the leaflets increased significantly relative to the unrepaired valve. These data demonstrate the potential for computational simulations to aid in the pre-procedural evaluation of possible complications such as chordal rupture and leaflet perforation following percutaneous edge-to-edge repair.

Unique mechanism of mitral valve prolapse in atrial septal defect: Three-dimensional insights into mitral complex geometry using real-time transesophageal echocardiography.

Mitral valve prolapse (MVP) is often identified in patients with atrial septal defect (ASD), which occasionally require surgical intervention at the time of ASD closure or even long after the surgery. Ventricular and valvular geometric characteristics in preoperative ASD patients were evaluated by three-dimensional (3D) transesophageal echocardiography. Mitral valve (MV) complex geometry was quantitatively measured by 3D transesophageal echocardiography in 11 ASD patients (Qp/Qs>1.5) and 11 controls. The ASD group had a significantly larger indexed prolapse volume and height, with a larger anterior mitral leaflet than controls (0.53 [0.33-0.75] vs 0.057 [0.027-0.11] mL/m2 , P=.0001; 2.89 [2.13-3.50] vs 0.92 [0.48-1.32] mm/m2 , P<.0001; 391.3 [346.4-445.1] vs 295.3 (281.9-330.0) mm2 /m2 , P=.011, respectively). The right ventricular (RV)-to-left ventricular (LV) end-systolic diameter ratio was larger in the ASD group than in the control group (1.34 [0.96-1.45] vs 0.85 [0.75-0.88], P=.004). The indexed inter-papillary muscle distance (IPMD) was significantly shorter in the ASD group than in the control group (7.77 [6.55-8.24] vs 9.71 [8.64-10.8] mm/m2 , P=.011). IPMD was significantly correlated with the RV-LV end-systolic diameter ratio (r=-.70, P=.017). Inward shift of the LV papillary muscle tips due to RV dilation may be a major mechanism of MV prolapse in ASD. At the same time, positive remodeling of the anterior leaflet was observed in the ASD group, which may compensate for the billowing leaflet geometry to maintain effective coaptation. Three-dimensional assessment of the MV apparatus geometry will help to further understand perioperative mitral regurgitation in patients with ASD.

Prognostic value of mitral valve tenting area in patients with functional mitral regurgitation

Mitral valve (MV) repair in functional mitral regurgitation is still associated with suboptimal outcomes. Our goal was to determine whether the clinical outcome following MV repair correlates with preoperative tenting parameters. We retrospectively identified consecutive patients with functional mitral regurgitation who underwent an isolated MV annuloplasty during a 7-year period (2010-2016) from our institutional database. Preoperative tenting parameters (i.e. tenting height, coaptation length, tenting area, posterior mitral leaflet and anterior mitral leaflet angles and interpapillary muscle distance) were systematically measured. The primary end point was the composite of survival and freedom from adverse cardiac events. The follow-up protocol consisted of a structured clinical questionnaire and an analysis of the echocardiographic data. A total of 240 patients (mean age 67.8 ± 9.8 years, 57% of men) were analysed. The overall 5-year survival rate for the whole study cohort was 74.7 ± 4.2%, and freedom from adverse cardiac events was 84.8 ± 3.4%. A tenting area ≥2.4 cm2 was identified as a cut-off value, independently predicting the composite primary study end point (hazard ratio 2.0; P = 0.03). Furthermore, a Kaplan-Meier analysis revealed a strong tendency towards worse 5-year outcomes in patients with a tenting area ≥2.4 cm2 (n = 153) versus patients with a tenting area <2.4 cm2 (n = 87) (65.3 ± 5.5% vs 77.1 ± 6.3%; P = 0.06). MV annuloplasty is associated with acceptable clinical and echocardiographic outcomes in patients with functional mitral regurgitation 5 years postoperatively. A preoperative tenting area ≥2.4 cm2 showed a strong trend towards a worse 5-year survival rate and an increased risk of adverse cardiac events after an isolated MV annuloplasty.

The effects of cardiac resynchronization therapy on left ventricular and mitral valve geometry and secondary mitral regurgitation in patients with left bundle branch block.

Secondary mitral regurgitation (MR) is common in patients with left bundle branch block (LBBB) undergoing cardiac resynchronization therapy (CRT). We aimed to define CRT effects on left ventricular (LV) and mitral valve (MV) geometry, and their correlation with MR severity. Forty-one patients with LBBB and ≥mild secondary MR underwent CRT between 2009 and 2012, and had baseline and follow-up echocardiograms available. Repeated measure and linear regression analyses were performed to assess for changes in MV and LV geometry and MR severity, and associations with follow-up MR grade. The mean age and baseline QRS duration were 65.5±14.9years and 160±24ms. At a mean follow-up of 2.6±1.8years, there was an increase in LV ejection fraction and reductions in LV end-systolic volume index, MR grade, and end-systolic interpapillary muscle distance (P<.05 for all). Linear correlations were observed between follow-up MR grade and baseline MV tenting height (r=.44), left atrial volume index (r=.41), LV end-systolic volume index (r=.4), MV tenting area (r=.38), LV ejection fraction (r=-.34), and end-systolic interpapillary muscle distance (r=.34) (P<.05 for all). Multiple regression analysis revealed associations between follow-up MR grade and baseline MV tenting height (β/mm=0.42, P=.006) and left atrial volume index (β/mL/m2 =0.4, P=.008), independent of QRS duration (β/ms=-0.07; P=0.6) and nonischemic cardiomyopathy (β=-0.34, P=.02). Cardiac resynchronization therapy in patients with LBBB and secondary MR results in LV and MV geometric reverse remodeling and decreases MR severity. Extent of baseline MV tethering is independently associated with persistent MR at follow-up.

Mathematical Blueprint of a Mitral Valve

Mathematical modeling tries to simplify understanding and proposes a fundamental mechanism that governs the motion and function of a complex biological system such as a mitral valve (MV) motion which represents a dynamic interplay between papillary muscle (PM) position in the context of left ventricular (LV) shape dynamics. Current therapeutic strategies to intervene on the MV may not have exploited these relationships due to lack of understanding of the interactions. We present a MV 3D mathematical model characterized by LV shape dynamics to understand fundamental working principles of ventriculo-papillary-mitral complex. A complex 3D functional unit of MV apparatus was mathematically modeled based on a principle of dynamics. The model comprises of primary components including the annulus, anterior leaflet, posterior leaflet, chordae tendineae, anterior and posterior PM, and LV wall based on normal anatomical reference values from published series. Simulations based on Carpentier's classification of MV disease were created as well as based on LV shape dynamics and presented graphically. Autodesk Inventor (Autodesk Inc., San Rafael, CA) and Matlab (Mathworks, Natick, MA) were used for modeling and analysis. A stepwise analysis and mathematical models of the annulus, leaflets, chords, PMs, and LV were obtained by combining finite element analysis and computerized model creations. The model was then applied to Carpentier's functional classification. PM positions extrapolated based on different LV deformation in normal and mitral regurgitation (MR) model resulted in a different degree of MV leaflet coaptation with regurgitation (presented numerically and graphically). Abnormal MV coaptation was amended by manipulating PM positions independent with LV size or shape deformation, demonstrating that PM positioning maneuver may improve leaflet coaptation. LV dilation combined with increased interpapillary muscle distance turned out to intensify the level of leaflet prolapse, creating even greater regurgitation volume. Our mathematical model may provide a clue to complex interactions in play within a mitral, papillary, and LV complex. The model offers a possibility of manipulating various variables to obtain the desired outcome.

Beneficial effects of restrictive annuloplasty on subvalvular geometry in patients with functional mitral regurgitation and advanced cardiomyopathy

ObjectivesThe effects of restrictive mitral annuloplasty (RMA) on subvalvular geometry remains unknown. We evaluated changes in left ventricular (LV) function, severity of mitral regurgitation (MR), and leaflet tethering parameters after RMA and clarified their associations. MethodsIn 44 patients with clinically relevant functional MR who underwent RMA, distances between papillary muscle (PM) tips and anterior mitral annulus (PM tethering distance), leaflet angles relative to lines connecting annuli, and interpapillary muscle distance (IPMD) were serially quantified. ResultsOne month after surgery, LV function and MR severity improved with decreased anterior (34 ± 5 to 30 ± 4 mm) and posterior PM tethering distance (37 ± 4 to 32 ± 4 mm), anterior leaflet angle (32 ± 8° to 22 ± 7°), and IPMD (31 ± 6 to 25 ± 5 mm), whereas these variables remained abnormal and posterior leaflet angle increased (34 ± 8° to 48 ± 14°; P < .01 for all). During follow-up (66 ± 37 months), these effects were maintained in 33 patients without MR recurrence, whereas 11 with it showed worsened tethering with less LV function recovery. Multiple linear regression analyses identified that change in MR severity from baseline to 12-month examination independently associated with corresponding change in IPMD (parameter estimate of 0.100 with standard error of 0.039; P = .019) and that in posterior PM tethering distance (parameter estimate of −0.104 with standard error of 0.045; P = .035), whereas not with change in posterior-leaflet angle. The IPMD change was independently associated with change in LV end-systolic dimension (parameter estimate of 0.299 with standard error of 0.110; P = .013). ConclusionsThe RMA procedure partially relieved leaflet tethering, evidenced by decreased tethering distances and IPMD; the latter was the main determinant of MR. These beneficial effects might be mainly attributed to post-RMA reverse LV remodeling, potentially offsetting the negative effect of augmented posterior leaflet angle in selected patients.

Impact of cardiac resynchronization therapy on mitral valve apparatus geometry and clinical outcomes in patients with secondary mitral regurgitation.

Cardiac resynchronization therapy (CRT) may improve secondary mitral regurgitation (MR) in patients with cardiomyopathy. The effects on mitral valve (MV) and left ventricular (LV) geometry, however, have not been clearly defined. Between 2009 and 2012, 229 CRT implants were performed at a single academic center. Seventy-one had ≥mild MR at baseline and serial echocardiography, without subsequent MV intervention. The pre-CRT and follow-up echocardiograms were retrospectively reviewed for (1) MV and LV geometry measurements; (2) MR grade; and (3) LV remodeling indices. The mean age was 67±15years, and the cardiomyopathy was ischemic in 37 (52%). At a mean follow-up of 4.0±1.9years, there were significant improvements in LV ejection fraction and size, MR grade, MV tenting area and anterior leaflet tethering angle, and end-systolic interpapillary muscle distance (IPMD), and reductions in moderate-to-severe or severe MR (27% vs 15%; P=.04) and New York Heart Association functional class III/IV symptoms (83% vs 41%; P<.001). Multivariable analysis revealed the pre-CRT MV tenting height (OR 1.25, 95% CI 1.01-1.56; P=.04) and end-systolic IPMD (OR 1.14, 95% CI 0.99-1.32; P=.08) as independently associated with moderate or greater MR at follow-up. Finally, at 5years post-CRT implantation, the estimated survival and freedom from LV assist device or cardiac transplantation was 61%. CRT results in favorable effects on MV and LV geometry and decreases the prevalence of moderate-to-severe or severe MR and heart failure symptoms. The pre-CRT MV tenting height and IPMD are independently associated with persistent MR at follow-up.

Abstract 35: Transendocardial Mesenchymal Stem Cell Injection Demonstrates Reverse Remodeling Effects of Global LV Volumes and Enhanced Lateral Papillary Muscle Shortening

Rationale: Secondary mitral regurgitation (MR) carries a poor prognosis despite improvements in surgical and transcatheter interventions. Mesenchymal stem cell (MSC) therapy for heart disease reduces infarct size and left ventricle (LV) dilatation, reverses remodeling, and improves regional contractility and functional capacity. However, it is unknown if the benefits of MSC therapy on LV structure and function apply to lateral papillary muscle shortening, an important predictor of secondary MR severity. Hypothesis: Test the hypothesis that administration of MSCs promotes interpapillary muscle distance (IPMD) shortening. Methods/Results: This retrospective analysis draws on results from autologous or allogeneic MSC injection therapies in a Göttingen swine model of chronic ischemic cardiomyopathy (ICM). MRI was used to measure end-diastolic volume (EDV), end-systolic volume (ESV), diastolic/systolic IPMD, and IPMD shortening. NOGA mapping and angiographic tracings of left ventriculography allowed for assessment of the effect of injection localized to papillary muscles (defined as injection within cardiac segments 4, 6, 10 and 12 in the 16-segment model). Three months after stem cell injection, EDV increased in both placebo- (12.2±3.6 mL; p=0.002) and MSC- (10.2±2.6 mL; p=0.03) treated swine. ESV increased only in placebo- (7.1±2.2 mL; p=0.003) but not MSC- treated swine. Systolic IPMD was maintained with MSC therapy (1.20±0.74 mm; p=0.33) but increased in placebo (1.83±0.60 mm; p=0.01). Systolic IPMD was preserved whether MSC injection was localized to papillary muscle (0.53±0.49 mm; p=0.44) or not (0.22±0.40 mm; p=0.24). Notably, IPMD shortening was significantly greater in MSC- (8.1±5.6%; p=0.02) but not placebo-injected (4.7±5.0%; p=0.69) swine. There were no between group differences in IPMD shortening (p=0.08). Conclusion: This study is the first to show that transendocardial MSC injections significantly enhanced IPMD shortening and lateral interpapillary muscle contraction in a model of chronic ICM. This effect was independent of injection site.

Papillary muscle approximation in mitral valve repair for secondary MR.

Ischemic mitral regurgitation (IMR) is a complex disorder occurring after a myocardial infarction and affecting both the mitral valvular and subvalvular apparati. Several abnormalities can be detected in IMR as annular dilatation, leaflet tethering with impaired coaptation and papillary muscle (PM) displacement along a posterior, apical or lateral vectors. Treatments available include, beside myocardial revascularization, mitral-valve repair or chordal-sparing replacement. Repair is normally achieved downsizing the mitral valve annulus with a rigid or semirigid ring. However, considering the involvement of the subvalvular apparatus, techniques addressing the PM have been developed. The rationale at the basis of this strategy relies in the possibility to reduce the interpapillary muscle distance restoring the geometry of the left ventricle (LV) and ultimately resolving the leaflet tethering at the basis of IMR. Subvalvular apparatus surgical approaches include the papillary muscle approximation (PMA), surgical relocation and PM sling. Improved outcomes in terms of postoperative positive left ventricular remodeling and recurrence of mitral regurgitation have been reported, but more investigations are required to confirm the efficacy of subvalvular apparatus surgery. Application of finite element analysis to improve preoperative and intraoperative planning and achieve a correct and durable repair by means of subvalvular surgery is an exciting new avenue in IMR research.

Left ventricle-mitral valve ring size mismatch: understanding the limitations of mitral valve repair for ischemic mitral regurgitation.

There are 750,000 patients diagnosed with a myocardial infarction in the United States yearly, of which approximately 25% will develop an ischemic cardiomyopathy complicated by significant mitral regurgitation (MR) (1,2). The occurrence of ischemic MR is associated with significant morbidity and mortality, which increases commensurate with the MR severity (2). It is caused by the abnormal mitral valve geometry that develops after the onset of left ventricular (LV) remodeling and dilatation, which results in posterolateral and apical papillary muscle displacement, impaired systolic shortening of the interpapillary muscle distance, and mitral valve leaflet tethering (3,4). The subsequent disruption of the mitral valve closing-tethering forces leads to an incomplete systolic mitral valve closure and the development of ischemic MR. A dilated mitral annulus is also a common finding; however, its role in the development versus exacerbation of ischemic MR, is not clearly defined (4,5).

Combined papillary muscle sling and ring annuloplasty for moderate-to-severe secondary mitral regurgitation.

There is a 30-60% incidence of recurrent mitral regurgitation (MR) after mitral valve annuloplasty (Ring) for secondary MR. A concomitant papillary muscle sling (Ring+Sling) may improve valve repair by providing a more physiologic geometry of the mitral apparatus. We retrospectively identified 58 consecutive patients with moderate-to-severe secondary MR who underwent a Ring+Sling repair, between March 2008 and May 2015. A Ring+Sling consisted of combined annuloplasty and papillary muscle approximation, utilizing a 4-mm polytetrafluoroethylene graft placed around the base of each muscle. Comparison of echocardiographic variables with patients who underwent a Ring only was performed utilizing 2:1 propensity-score matching (Ring+Sling = 34; Ring = 17). The baseline demographics were similar between the groups. The mean time to follow-up echocardiogram was 10.1 months (range 0.25-42 months). At follow-up, a Ring+Sling repair was associated with a lower mitral valve tenting height (p = 0.005), mitral valve tenting area (p = 0.009), and interpapillary muscle distance (p = 0.001); a smaller posterior leaflet tethering angle (p = 0.003); and a greater leaflet coaptation length (p = 0.002), when compared with Ring only. Recurrence of moderate or greater MR occurred significantly less in the Ring+Sling group (14.7%), as compared with Ring only (35.3%) (p < 0.001). Finally, actuarial survival at three years was 87% for Ring+Sling, and 82% for Ring only (p = 0.49). A Ring+Sling for secondary MR results in favorable changes in the mitral valve apparatus geometry, and is associated with less MR recurrence in the early postoperative period. Longer-term follow-up is needed to assess its durability and effects on left ventricular remodeling and survival.

Chronic ischemic mitral regurgitation and papillary muscle infarction detected by late gadolinium-enhanced cardiac magnetic resonance imaging in patients with ST-segment elevation myocardial infarction.

BackgroundBoth papillary muscle infarction (PMI) and chronic ischemic mitral regurgitation (CIMR) are associated with reduced survival after myocardial infarction. The influence of PMI on CIMR and factors influencing both entities are incompletely understood.ObjectivesWe sought to determine the influence of PMI on CIMR after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) and to define independent predictors of PMI and CIMR.MethodsBetween January 2011 and May 2013, 263 patients (mean age 57.8 ± 11.5 years) underwent late gadolinium-enhanced cardiac magnetic resonance imaging and transthoracic echocardiography 4 months after PCI for STEMI. Infarct size, PMI, and mitral valve and left ventricular geometric and functional parameters were assessed. Univariate and multivariate analyses were performed to identify predictors of PMI and CIMR (≥grade 2+).ResultsPMI was present in 61 patients (23 %) and CIMR was present in 86 patients (33 %). In patients with PMI, 52 % had CIMR, and in patients without PMI, 27 % had CIMR (P < 0.001). In multivariate analyses, infarct size [odds ratio (OR) 1.09 (95 % confidence interval 1.04–1.13), P < 0.001], inferior MI [OR 4.64 (1.04–20.62), P = 0.044], and circumflex infarct-related artery [OR 8.21 (3.80–17.74), P < 0.001] were independent predictors of PMI. Age [OR 1.08 (1.04–1.11), P < 0.001], infarct size [OR 1.09 (1.03-1.16), P = 0.003], tethering height [OR 19.30 (3.28–113.61), P = 0.001], and interpapillary muscle distance [OR 3.32 (1.31–8.42), P = 0.011] were independent predictors of CIMR.ConclusionsThe risk of PMI is mainly associated with inferior infarction and infarction in the circumflex coronary artery. Although the prevalence of CIMR is almost doubled in the presence of PMI, PMI is not an independent predictor of CIMR. Tethering height and interpapillary muscle distance are the strongest independent predictors of CIMR.

Multislice computed tomography-guided surgical repair of acquired posterior left ventricular aneurysms: demonstration of mitral valve and left ventricular reverse remodelling.

Involvement of the mitral valve (MV) apparatus represents a challenge in surgical ventricular repair (SVR) of posterior left ventricular (LV) aneurysms. This study sought to investigate whether multislice computed tomography (MSCT) assessment can be used to optimize the surgical procedure for posterior LV aneurysms. Thirty patients (m : w = 24 : 6, age 38-78, median 66 years; mean New York Heart Association class 2.98) with posterior LV aneurysm were operated upon. MSCT was performed in 24 patients before and after surgery. End-diastolic and end-systolic volumes of LV and aneurysm were indexed to body surface area (LVEDVI/LVESVI, AEDVI/AESVI). The MV apparatus was characterized by coaptation distance (CD), tenting area (TA), MV closure angle (MVCA), MV annulus area (MVAA) and interpapillary muscle distance (IMD). Thirty-day mortality was 10% and 5-year survival rate was 83%. After surgery, LVEDVI decreased from 151.2 ± 84.1 to 85.7 ± 28.3 ml/m(2) (P = 0.001) and LVESVI from 110.6 ± 88.8 to 50.2 ± 22.9 ml/m(2) (P = 0.001). LV ejection fraction increased from 31.5 ± 15.1 to 43.4 ± 9.9% (P = 0.001). Preoperative MSCT showed significantly higher values of MVAA, CD and TA in patients who needed MV repair or replacement. Postoperative reduction of mitral regurgitation in patients without MV surgery corresponded with significant reduction in intercommissural diameter, anteroposterior diameter, MVAA, TA, CD, MVCA and IMD. MSCT represents an excellent diagnostic tool for the assessment of MV and LV geometry. MSCT-guided SVR of submitral LV aneurysms leads to excellent mid-term results. On the basis of the MSCT assessment, we propose an algorithm for surgical planning in posterior LV aneurysms.

Cardiac computed tomography assessment of the near term impact of percutaneous ventricular restoration therapy (parachute(®) ) on mitral valve geometry.

The aim of current study is to assess the near term impact of percutaneous ventricular restoration therapy (PVR), Parachute(®) on mitral valve (MV) geometry by cardiac computed tomography (CCT). Recent data demonstrates the feasibility of PVR for treatment of post anterior myocardial infarction (MI) heart failure. Little is known, however, about the interaction of the device and left ventricular structures, particularly the MV apparatus. This is a retrospective Core Laboratory analysis of Parachute Trials' CCT data. Patients with paired (before and after Parachute implant) CCT acquisitions were included into analysis. MV geometric parameters were measured. Thirty-three patients were included in the analysis. The mean time of follow-up CCT post procedure was 188 ± 52 days. There were significant reduction in tenting height (A1P1: -1.70 ± 1.89 mm, -17.40 ± 20.20%; A2P2: -1.43 ± 1.89 mm, -12.10 ± 15.00%; A3P3: -1.54 ± 1.58 mm, -15.50 ± 15.20%, P < 0.001), tenting volume (-0.93 ± 0.60 mm3, -22.00 ± 11.40%, P < 0.001), systolic interpapillary muscle distance (-2.22 ± 2.11 mm, -7.51 ± 7.23%, P < 0.001) and diastolic interpapillary muscle distance (-3.14 ± 2.20 mm, -8.46 ± 5.73%, P < 0.001) post PVR. In post anterior MI heart failure patients, PVR has favorable near term impact on MV geometry as assessed by CCT. © 2015 Wiley Periodicals, Inc.