Papillary Muscle Approximation Research Articles

Comparing surgical techniques and results of secondary ischemic mitral regurgitation: a state-of-the-art literature review.

Surgery for mitral valve disease is a developing area with a wide range of surgical options. There is growing evidence on the best approach for secondary ischemic mitral regurgitation (SIMR) when the pathology is within the ventricle. The goal of this literature review is to provide a comprehensive comparison of surgical treatments for SIMR. The initial screening process included PubMed, Medline and Embase to identify randomized controlled trials, propensity-matched observational series, meta-analyses and unmatched observational series. The terms used were 'mitral valve disease', 'secondary mitral regurgitation', 'secondary ischemic mitral regurgitation', 'functional mitral regurgitation', 'restrictive mitral annuloplasty', 'subvalvular repair', 'Trans Catheter Edge to Edge Repair and echocardiography coupled with secondary mitral regurgitation', 'secondary ischemic mitral regurgitation', and 'functional mitral regurgitation'. Six strategies have been identified for treating SIMR. These include mitral valve replacement (MVR), restrictive mitral annuloplasty, surgical revascularisation (with and without mitral annuloplasty), subvalvular procedures [papillary muscle (PM) approximation, PM relocation, ring and string procedure], procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement), and transcatheter heart valve therapy. There is a deficiency of robust empirical data to enable meaningful comparisons between MVR, mitral valve repair (including subvalvular repair), and transcatheter mitral valve procedure. This review will definitively analyze the current outcomes of transcatheter mitral valve procedure using the edge-to-edge mitral valve repair technique and standard surgical mitral valve procedures in patients with secondary mitral regurgitation (MR). In addition, the seminar highlights the role of left ventricular assist devices in managing SIMR. It discusses the advantages and limitations of each intervention. Currently, there is no consensus on the optimal management strategy for patients with SIMR. Therefore, a multidisciplinary cardiac team should manage patients with secondary MR to ensure the best outcome by matching the ideal intervention with the patient.

Mid-term outcomes of right ventricular papillary muscle approximation for severe functional tricuspid regurgitation.

Recurrence of tricuspid regurgitation (TR) after tricuspid annuloplasty can occur in cases where a dilated right ventricle exists and subsequent leaflet tethering follows. We previously reported a new technique of the right ventricular papillary muscle approximation (RV-PMA) for functional TR associated with leaflet tethering. The objective of this study is to elucidate the mid-term outcomes and evaluate the durability of RV-PMA. Between January 2014 and March 2023, we applied RV-PMA in 20 patients of advanced functional TR with severe leaflet tethering. The indication of the technique was severe TR with leaflet tethering height >8 mm, and/or a right ventricular end-diastolic diameter >45 mm. The patients were followed up with echocardiography before discharge and at annual interval thereafter. There was no perioperative mortality. In the echocardiography performed before discharge, TR was decreased to mild or less in 85%, and a significant improvement in right ventricular end-diastolic diameter and tethering height were achieved (53-45 mm and 11.1-4.4 mm, respectively). Furthermore, during the median 3-year follow-up period, TR was kept controlled mild or less in 80% of the cases. RV-PMA is considered to be a safe, effective and durable technique as an additional approach for tricuspid annuloplasty.

Abstract 14699: Effects of Papillary Muscle Approximation and Annuloplasty Ring Sizing for Functional Mitral Regurgitation Repair in Enlarged Ventricles

Introduction: Our recent large animal study showed that papillary muscle approximation (PMA) repairs functional mitral regurgitation (FMR) and increases valve coaptation in enlarged left ventricles without negatively affecting ventricular function. However, since PMA does not reduce mitral annular dilation, addition of annuloplasty ring might be beneficial for such repair. In this study, we used computational modeling to investigate the benefit of the addition of annuloplasty to PMA and the effects of ring sizing on FMR repair in enlarged ventricles. Methods: 3D echo images were obtained in 3 pigs with heart failure, enlarged ventricles, and FMR. Each echo dataset was segmented, and computational model of the mitral valve was developed. To mimic PMA repair, the papillary muscles were drawn together in diastole. A true-sized annuloplasty ring of 40 mm and two downsized-rings of 38 mm and 36 mm were then added to each model. Leaflet closure was simulated and mitral valve geometry and biomechanics in peak systole were evaluated ( Fig A-B ). Results: On average, compared to pre-repair, PMA increased coaptation area by 30.6%, while the addition of annuloplasty increased this area by 85.1% with 40 mm, 138.1% with 38 mm, and 190.6% with 36 mm ring. Tenting area was reduced by 45.8% after PMA, 64.1% with the addition of 40 mm ring, 70.6% with 38 mm, and 76.5% with 36 mm ring. PMA reduced tension forces in chordae by 19.8%, while adding true-sized ring reduced forces by 16.4%. Annular downsizing allowed to reduce chordal forces by 31.2% with 38 mm, and 43.0% with 36 mm ring. Peak leaflet stress was observed on the P2 cusp, and PMA reduced it by 26.9%. True-sized ring reduced peak stress by only 10.7%, while 38 mm ring by 29.9%, and 36 mm by 43.7% ( Fig C ). Conclusions: Addition of true-sized ring to PMA further improved systolic valve geometry but not biomechanical parameters. Annular downsizing added to PMA was more beneficial for FMR repair, as it improved both mitral valve geometry and biomechanics.

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.

Right ventricular papillary muscle approximation to the septum as an adjunct technique during tricuspid valve repair in congenital heart surgery

ObjectiveTricuspid regurgitation is often caused by leaflet splaying from displaced papillary muscles or ventricular dilatation. Traditional annuloplasty may not address this mechanism. The present study describes a single institution's experience using right ventricular papillary muscle approximation for tricuspid valve repair. MethodsRight ventricular papillary muscle approximation consists of suturing the anterior papillary muscle to a point of the septum (septum or septal papillary muscle) that optimizes leaflet coaptation. We describe our technique and analyze clinical data of patients undergoing tricuspid valve repair with right ventricular papillary muscle approximation during congenital heart surgery between 2012 and 2021. ResultsRight ventricular papillary muscle approximation was performed as an adjunct procedure in 207 of 825 tricuspid valve repairs (25.1%). Discharge tricuspid regurgitation grade was mild tricuspid regurgitation or less in 153 patients (73.9%), and 140 patients (67.6%) had mild tricuspid regurgitation or less at a median latest follow-up of 3.2 years (interquartile range, 0.7-6.8). Thirty patients (14.5%) underwent 11 early tricuspid valve reinterventions (3 due to right ventricular papillary muscle approximation dehiscence) and 21 late tricuspid valve reinterventions. Estimated 5-year freedom from tricuspid valve reintervention was 84% (95% CI, 77.0-89.2). Systemic right ventricle physiology (odds ratio, 2.88, P = .048) and multiple mechanisms of tricuspid regurgitation (odds ratio, 7.35, P = .038) were significant predictors of tricuspid valve reintervention on multivariable analysis. ConclusionsTricuspid valve repair with right ventricular papillary muscle approximation demonstrates acceptable short-term durability, but similar to other tricuspid valve repair strategies is less durable in patients with systemic right ventricle pressure and multiple mechanisms of tricuspid regurgitation. Right ventricular papillary muscle approximation is a safe and effective adjunct technique that should be considered in patients with tricuspid regurgitation caused by leaflet splaying from displaced papillary muscles or right ventricle dilatation.

Papillary muscle approximation in chronic ovine functional tricuspid regurgitation

ObjectiveIsolated tricuspid ring annuloplasty remains the surgical standard for functional tricuspid regurgitation repair but offers suboptimal results when right ventricular dilation and remodeling along with papillary muscle displacement is present. Addressing subvalvular remodeling with papillary muscle approximation may improve clinical outcomes. MethodsFunctional tricuspid regurgitation and biventricular dysfunction were induced in 8 healthy sheep by rapid ventricular pacing (200-240 bpm) for 27 ± 6 days. Subsequently, animals underwent cardiopulmonary bypass for implantation of sonomicrometry crystals on the tricuspid annulus, right ventricle, and papillary muscle tips. Papillary approximation sutures were anchored between anterior-posterior and anterior-septal papillary muscles and externalized through right ventricular free wall to epicardial tourniquets. After weaning from cardiopulmonary bypass, sequential papillary muscle approximations were performed. Simultaneous hemodynamic, sonomicrometry, and echocardiographic data were collected at baseline and after each papillary muscle approximation. ResultsWith rapid pacing, right ventricular fractional area change decreased from 59 ± 6% to 38 ± 8% (P < .001), whereas tricuspid annulus diameter increased from 2.4 ± 0.3 cm to 3.3 ± 0.6 cm (P = .003). Tricuspid regurgitation (0-4+) increased from +0 ± 0 to +3.3 ± 0.7 (P < .001). Both anterior–posterior and anterior–septal papillary muscle approximation significantly reduced functional tricuspid regurgitation from +3.3 ± 0.7 to +2 ± 0.5 and +1.9 ± 0.6, respectively (P < .001). Reduction of tricuspid insufficiency with both subvalvular interventions was associated with decreased distance of the anterior papillary muscle to the annular centroid. ConclusionsPapillary muscle approximations were effective in reducing severe ovine functional tricuspid regurgitation associated with right ventricular dilation and papillary muscle displacement. Further studies are needed to evaluate efficacy of this adjunct to ring annuloplasty in repair of severe functional tricuspid regurgitation.

Impact of Mitral Regurgitation Recurrence on Mitral Valve Repair for Secondary Ischemic Mitral Regurgitation.

The current guidelines still do not include specific recommendations on the use of subvalvular repair (SV-r) for treatment of ischemic mitral regurgitation (IMR). Therefore, the objective of our study was to evaluate the clinical impact of mitral regurgitation (MR) recurrence and ventricular remodeling on long-term outcomes after SV-r combined with restrictive annuloplasty (RA-r). We performed a subanalysis of the papillary muscle approximation trial, studying 96 patients with severe IMR and coronary artery disease undergoing restrictive annuloplasty alongside subvalvular repair (SV-r + RA-r group) or restrictive annuloplasty alone (RA-r group). We analyzed treatment failure differences, the influence of residual MR, left ventricular remodeling, and clinical outcomes. The primary endpoint was treatment failure (composite of death; reoperation; or recurrence of moderate, moderate-to-severe, or severe MR) within 5 years of follow-up after the procedure. A total of 45 patients showed failure of the treatment within 5 years, of which 16 patients underwent SV-r + RA-r (35.6%) and 29 underwent RA-r (64.4%, p = 0.006). Patients with significant residual MR presented with a higher rate of all-cause mortality at 5 years compared with trivial MR (HR 9.09, 95% CI 2.08-33.33, p = 0.003). MR progression occurred earlier in the RA-r group, as 20 patients in the RA-r group vs. 6 in SV-r + RA-r group had a significant MR 2 years after surgery (p = 0.002). RA-r remains a surgical mitral repair technique with an increased risk of failure and mortality at 5 years compared with SV-r. The rates of recurrent MR are higher, and recurrence occurs earlier, with RA-r alone compared to SV-r. The addition of the subvalvular repair increases the durability of the repair, thus extending all of the benefits of preventing MR recurrence.

Abstract 15499: Adjunctive Papillary Muscle Approximation With Undersizing Mitral Annuloplasty Improves Mitral Valve Mobility and Biomechanics to Repair Functional Mitral Regurgitation

Introduction: Undersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation (FMR) has failed to achieve durable results. Though FMR recurrence rates of 60% at 2 years are often cited, even at 30 days, nearly 30% of the patients had moderate or greater FMR in the CTSN trial. We previously demonstrated experimentally that adjunctive papillary muscle approximation (PMA) can improve valve function, with or without UMA. In this modeling study, we used patient specific mitral valve geometries to investigate the effects of UMA and UMA+PMA on mitral valve biomechanics. Methods: 3D ultrasound was obtained in 3 pigs with chronic heart failure and moderate or severe FMR. Each 3D echo was segmented, and computational valve models were developed. UMA was mimicked with ring sizes of 36, 32, and 28 mm ( Fig A ). PMA was then added to each ring size, and the outcomes were reassessed ( Fig B ). In each simulation, leaflet stresses and chordal forces, coaptation area, and tenting parameters were computed. Results: Compared to pre-repair, UMA increased coaptation area by 178.3% with 36 mm, 279.1% with 32 mm, and 356.7% with 28 mm ring ( Fig C ). With 36 mm ring, leaflet stresses increased by 4.3%, while smaller rings reduced stresses by 24.3% (32 mm) and 33.8% (28 mm) ( Fig D ). Chordal forces after UMA decreased by 37.6%, 50.6%, and 55.2% ( Fig E ). Leaflet mobility was improved, as tenting area decreased by 46.1%, 57.9%, and 67.5% ( Fig F ). Adding PMA, achieved better valve closure and coaptation without the need for excessive annular downsizing: tenting area decreased by 76.5%, 85.2%, and 92%, and coaptation area increased by 190.6%, 309.8%, and 386.4%. In addition, leaflet stresses were reduced by 17.4%, 38.5%, and 44.9%, and chordal forces by 48.1%, 63.7%, and 72.9%. Conclusions: Adjunctive addition of PMA repaired FMR and restored physiological mitral valve mobility even at 36 mm annular size, reducing the need for excessive annular undersizing and potentially resulting in a durable repair.

Abstract 9397: Sex-Based Differences in Outcomes After Mitral Valve Repair for Severe Secondary Mitral Regurgitation

Background: Sex-based differences in outcomes after mitral valve repair for severe secondary ischemic mitral regurgitation (SIMR) is poorly understood. We examined differences in outcomes between men and women after mitral valve repair for severe SIMR. Methods: 96 patients with SIMR were randomized to undergo either papillary muscle approximation (PMA) with restrictive mitral annuloplasty (RMA) or RMA alone to evaluate efficacy and safety. The primary endpoint was death and major adverse cardiac or cerebrovascular events (MACCE) at 5 years. Results: 38 of the 96 enrolled (39.5%) were women. Five-year survival was 68% in women and 78% men (HR 1.48; 95% CI 0.67-3.24). Men and women had similar mortality rates in the PMA (HR 2.64; 95% CI 0.77-9.04) and RMA group (HR 0.93; 95%CI 0.31-2.78). Freedom from MACCE at 5 years was lower among women than men (6% vs 23%; HR 1.89; 95%CI 1.20-2.98). The hazard for MACCE was higher in women in the PMA group alone (HR 3.00; 95% CI 1.50-6.02). Freedom from treatment failure was similar between sexes (55% in women and 69% in men; HR 1.58; 95% CI 0.81-3.06). Similar functional status (26.3% vs 24.1%) and rehospitalization rates (23.7% vs 24.1%) were noted at 5 years. There were no significant differences in the percentage of change over 5 years in LVESD and LVEDD between the sexes. Conclusion: Women with SIMR who underwent mitral valve repair displayed no significant differences in the degree of five-year survival. MACCEs however, recurred more frequently in women.

Abstract 15663: Trasapical Mitral Valve and Left Ventricular Reshaping to Repair Functional Mitral Regurgitation in a Dilated Ventricle

Background: The COAPT trial demonstrated that repair of functional mitral regurgitation (FMR) in heart failure (HF) improves prognosis, only when the LV end diastolic diameter is &lt;65mm. A significant need exists for a new therapy that can address both FMR and the LV in patients with LV EDD&gt;65mm. In this study, we report a novel beating heart transapical device that can address FMR by beating heart papillary muscle approximation (PMA), and reduces the LV size and sphericity as well. Preclinical efficacy of this novel device in a swine HF/FMR model is reported. Methods: The device was prototyped using biocompatible 3D printed parts (Fig A), and a delivery catheter was custom designed for beating heart deployment (Fig B). In 7 healthy pigs, and 4 pigs induced with chronic post-myocardial infarction HF, with moderate or greater FMR, the device was implanted via a transapical access. The device was adjusted in steps - (step 1) reduce the inter-PM distance to an extent that FMR is mild or less; and (step 2) reshape the LV to achieve a 30% reduction in LV EDV and 25% reduction in sphericity index (SI). Echocardiography was used to assess mitral valve function and LV geometry, and LV function was assessed with invasive hemodynamics. Pigs were survived thereafter. Results: With this new device, MR was consistently reduced from moderate levels to none/mild. Mitral valve coaptation length increased from 3.49 ± 0.42 to 6.45± 1.13 mm (p=.019) and tenting area decreased from 158.09± 33 to 116.4± 16.7mm 2 (p=.05). LV EDV was reduced from 142.8± 29.6 to 97.5± 19.6ml (p=.025), SI was decreased from 0.67± 0.04 to 0.49± 0.07 (p=.0497) and IPMD was reduced from 23.5± 5.7 to 12.76± 3.0mm (p=.032). The device did not adversely impact cardiac output (6.59± 1.3 to 4.83± 1.6 LPM, p=.067) or E/A wave ratio (1.40± 0.23 to 1.35±0.29, p=.60). Conclusion: This novel transapical beating heart MV and LV reshaping device, significantly reduced FMR and reshaped the LV in this swine model.

Learning from Controversy and Revisiting the Randomized Trials of Secondary Mitral Regurgitation.

Until recently, conventional mitral valve surgery has been the treatment of choice even in secondary mitral regurgitation. Recent evidence, however, advocates the use of transcatheter edge-to-edge mitral valve repair (TEER) of the mitral valve. This has been reflected by the change in guidelines of the American College of Cardiology/American Heart Association. We reviewed the literature to shed light on the risks and benefits of all interventions, surgical, transcatheter and guideline-directed medical therapy. Secondary mitral regurgitation occurs due to an imbalance between closing forces and tethering forces. Given the pathology extends beyond the valve alone, treatment should be directed at restoring the geometrical shape of the left ventricle alongside the valve. Myocardial revascularization plays a pivotal role in preventing recurrence. The role of papillary muscle approximation in addition to restrictive mitral annuloplasty should be considered in a select group of patients. We also reviewed the current literature on TEERs from the COAPT and Mitra-FR trials while highlighting the concept of proportionate/disproportionate MR which may help identify which patients benefit from mitral valve restoration. Treatment of this condition will require robust randomized trials alongside the use of state-of-the-art imaging technologies available with the full complement of the multidisciplinary team to ensure the best outcomes for each patient.

A Nationwide Survey of Surgical Treatment for Severe Ischemic Mitral Regurgitation.

Objective: Mitral subvalvular procedures in addition to restrictive annuloplasty are promising for ischemic mitral regurgitation (IMR). However, the prevalence and efficacy of specific subvalvular repair in severe IMR have not been elucidated. This is the first nationwide survey regarding surgeons’ attitudes toward IMR in Japan.Methods: A questionnaire was sent to 543 institutions. From 2015 to 2019, numbers of elective first-time mitral valve replacement (MVR) with/without complete chordal preservation (CCP)/papillary muscle approximation (PMA) and mitral valvuloplasty (MVP) with/without papillary muscle relocation (PMR)/PMA in patients with severe IMR were collected. Concomitant procedures for coronary artery, tricuspid valve, and arrhythmia could be included but left ventricular reconstruction was excluded.Results: Completed questionnaires were received from 286 institutions (52.7%). The majority (90%) had less than 20 cases within 5 years. The number of MVP (1413, 61.5%) surpassed MVR (886, 38.5%). CCP was performed in half of MVR (50.0%), while PMA was included in only 1.9% of MVR. PMA and PMR were also performed infrequently, in only 7.7% and 10.9% of MVP, respectively.Conclusion: Japanese surgeons aggressively perform MVP for severe IMR. Subvalvular repair was also aggressively performed in addition to MVR, but not to MVP. A multicenter registry study is in progress.

Exploring the Operative Strategy for Secondary Mitral Regurgitation: A Systematic Review.

Background Mitral valve disease surgery is an evolving field with multiple possible interventions. There is an increasing body of evidence regarding the optimal strategy in secondary mitral regurgitation where the pathology lies within the ventricle. We conducted a systematic review to identify the benefits and limitations of each surgical option. Methods A systematic review of the literature was performed to identify pertinent randomized controlled trials (RCTs), propensity-matched observational series, and meta-analyses which were considered initially and followed by unmatched observational series using the MEDLINE, Ovid EMBASE, and Cochrane Library. Results We identified 6 different strategies for treating secondary mitral valve regurgitation: mitral valve replacement, restrictive mitral annuloplasty, surgical revascularization (with and without mitral annuloplasty), subvalvular procedures (papillary muscle approximation, papillary muscle relocation, ring and string procedure), and procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement) alongside transcatheter heart valve therapy. We also highlighted the role of left ventricular assist devices in the management of this condition. The benefits and limitations of each intervention are highlighted. Conclusion There is currently no unanimous and shared strategy for the optimal treatment of patients with secondary IMR. The management of patients with secondary mitral regurgitation must be entrusted to a multidisciplinary Heart Team to ensure ideal intervention and patient matching for the best outcomes.

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.

Papillary muscle approximation reduces systolic tethering forces and improves mitral valve closure in the repair of functional mitral regurgitation

BackgroundUndersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation (FMR) lacks durability, as it forces leaflet coaptation without relieving the subleaflet tethering forces. In this biomechanical study, we demonstrate that papillary muscle approximation (PMA) before UMA can drastically relieve tethering forces and improve valve function, without the need for significant annular downsizing. MethodsAn ex vivo model of FMR was used, in which pig mitral valves were geometrically perturbed to induce FMR, and the repairs were performed. Nine pig mitral valves were studied in the following sequence: normal (baseline), FMR, true-sized annuloplasty to 30 mm (true-sized ring [TSR]), and undersized annuloplasty to 26 mm (down-sized ring [DSR]), along with concomitant PMA at both ring sizes. Mitral regurgitation, valve kinematics, and chordal forces were measured and compared among the groups. ResultsFMR geometry induced a mean regurgitant fraction of 16.31 ± 7.33% compared with 0% at baseline. TSR reduced the regurgitant fraction to 6.05 ± 5.63%, whereas DSR reduced it to 5.06 ± 6.76%. The addition of PMA before the use of these rings reduced the mean regurgitant fraction to 3.87 ± 6.79% with the TSR (TSR + PMA) and 3.71 ± 6.25% with the DSR (DSR + PMA). Mean peak anterior and posterior marginal chordal forces were elevated to 0.09 ± 0.1 N and 0.12 ± 0.1 N, respectively, with FMR and were not reduced by annuloplasty of either sizes. The addition of PMA significantly reduced these forces to 0.23 ± 0.02 N and 0.51 ± 0.04 N. ConclusionsThis biomechanical study demonstrates that PMA relieves tethering forces, and concomitantly with annuloplasty it mobilizes the leaflets to achieve physiological valve closure. Such a result could be achieved without the need for extensive annular downsizing.

Abstract 16874: Papillary Muscle Approximation Relieves Tethering Forces and Improves Systolic Mitral Valve Kinematics in an Ex-Vivo Model of Functional Mitral Regurgitation

Introduction: Undersizing annuloplasty (UA), which is the current standard to correct functional mitral regurgitation (FMR) is effective, but the resulting unphysiological systolic geometry causes FMR recurrence. On the other hand, papillary muscle approximation (PMA), a sub-annular technique, reduces inter-papillary separation and tethering forces, mobilizing the leaflets. Objective: To investigate the effect of PMA on mitral valve tethering forces and systolic coaptation geometry, compared to UA. Methods: A left heart model with pig mitral valves was used to create a tethered mitral valve geometry and to perform surgical repairs ( Fig. A ). Mitral valve geometry, and marginal and strut chordal forces acting on both leaflets were measured. Eight individual pig valves (n=8) were studied, with hemodynamic and mechanics data acquired at normal geometry (BASELINE) ( Fig. B) , after tethering (FMR) ( Fig. C) , undersizing annuloplasty (UA) to size 34 (Edwards Lifesciences Physio ring) ( Fig. D) , papillary muscle approximation (PMA), and combination (PMA+UA). Results: Tenting height, which increased after FMR, was least with PMA (0.46 cm± 0.21) and PMA+UA (0.50± 0.16) but remained significantly high with UA (0.73±0.21, p=0.03) ( Fig. E ). Excursion angles of anterior and posterior leaflets were restored close to baseline values after PMA and PMA+UA but remained significantly tethered after UA ( Fig. F &amp; G ). Tethering of the valve increased the strut and marginal chordae forces from 0.47 and 0.14 N to 0.89 and 0.21 N, an increase of 89% and 50% respectively. PMA reduced the forces by 47% and 34%, and PMA+UA reducing it by 43% and 34%to 0.51 while UA only reduced it by 15% and 20% ( Fig. H &amp; I ). Conclusion: PMA significantly reduced the tethering forces on both marginal and strut chordae of both leaflets. Decrease in tethering forces restored the physiologically favorable valve geometry enabling better leaflet mobility and coaptation compared to UA.

Undersizing mitral annuloplasty alters left ventricular mechanics in a swine model of ischemic mitral regurgitation

ObjectiveUndersizing mitral annuloplasty (UMA) is a frequently used surgical repair technique to correct ischemic mitral regurgitation in patients with heart failure. In this study, we sought to test the hypothesis that downsizing the mitral annulus can adversely affect the shape and mechanics of the left ventricle inhibiting its functional recovery. MethodsEighteen farm swine that underwent an inferolateral myocardial infarction and developed ischemic mitral regurgitation of >2+ severity after 2 months were assigned as follows: 9 swine received an undersized mitral annuloplasty, 6 received papillary muscle approximation (PMA), and 3 animals did not receive any other intervention. Animals lived another 3 months and cardiac magnetic resonance imaging was performed before termination to assess ventricle mechanics and function. ResultsEjection fraction was comparable between the 2 repair groups before surgery, but was significantly lower in UMA at 38.89% ± 7.91% versus 50.83% ± 9.04% in the PMA group (P = .0397). Animals receiving UMA had lower regional peak fractional shortening and reduced systolic and diastolic radial velocities compared with PMA and in some regions were lower than sham. Animals that underwent UMA had higher circumferential strain than sham, but lower than PMA. UMA animals have lower longitudinal strain compared to sham group and lower LV torsion than PMA. ConclusionsUndersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricle mechanics. Mitral valve repair strategies should focus not only on restoring valve competence, but preserving ventricle mechanics.

Transcatheter left ventricular reshape of apical ischaemic aneurysm achieves left ventricular remodelling, improves wall motion, causes papillary muscle approximation, and a reduction of secondary MVR.

Transcatheter left ventricular reshape of apical ischaemic aneurysm achieves left ventricular remodelling, improves wall motion, causes papillary muscle approximation, and a reduction of secondary MVR.

Papillary muscle intervention vs mitral ring annuloplasty in ischemic mitral regurgitation.

Background and AimsThe main pathophysiological factor of chronic ischemic mitral regurgitation (MR) is the outward displacement of the papillary muscles (PMs) leading to leaflet tethering. For this reason, papillary muscle intervention (PMI) in combination with mitral ring annuloplasty (MRA) has recently been introduced into clinical practice to correct this displacement, and to reduce the recurrence of regurgitation.MethodsA meta‐analysis was conducted comparing the outcomes of PMI and MRA performed in combination vs MRA performed alone, in terms of MR recurrence and left ventricular reverse remodeling (LVRR). A meta‐regression was carried out to investigate the impact of the type of PMI procedure on the outcomes.ResultsMR recurrence in patients undergoing both PMI and MRA was lower than in those who only had MRA (log incidence rate ratio, −0.66; lower‐upper limits, −1.13 to 0.20; I 2 = 0.0%; p = .44; Egger's test: intercept 0.35 [−0.78 to 1.51]; p = .42).The group with both PMI and MRA and that with only MRA showed a slightly higher reduction in left ventricular diameters (−5.94%; −8.75% to 3.13%,). However, in both groups, LVRR was <10%. No difference was detected between PM relocation/repositioning and papillary muscle approximation in terms of LVRR (p = .33).ConclusionsUsing PMI and MRA together has a lower MR recurrence than using MRA alone. No significant LVRR was observed between the two groups nor between the PMI techniques employed.

Сравнение возможностей логистической регрессии и искусственных нейронных сетей в прогнозировании результатов исследования на малой выборке

В настоящее время все чаще предпринимаются попытки сравнивать различные количественные модели для решения конкретных задач классификации данных. При этом в литературе отсутствуют данные о сравнении математических моделей в условиях малых выборок и сложных клинических ситуаций. Цель работы. Сравнить производительность моделей искусственных нейронных сетей и логистической регрессии в прогнозировании результатов исследования в условиях малой выборки. Материалы и методы. В симуляцию включена группа больных из 50 человек, которым была выполнена пластическая операция на митральном клапане. Для симуляции выбраны пять независимых переменных: пол, возраст, индекс массы тела, методика аппроксимации папиллярных мышц. Зависимая переменная – регургитация на митральном клапане в отдаленном периоде. Результаты. По данным логистической регрессии возник феномен разделения данных и получена огромная среднеквадратичная ошибка. По результатам анализа ROC-кривой выявлена зависимость между предиктором возраст и регургитацией на митральном клапане, площадь под кривой говорит о среднем уровне взаимосвязи. Результаты анализа предикторов с помощью искусственных нейронных сетей указывают на то, что основной вклад в качестве предиктора отсутствия регургитации оказывает процедура аппроксимации папиллярных мышц. С помощью теста De-Long проведено сравнение ROC-кривых регрессии и нейронных сетей по фактору возраст: z = 10.71, p &lt;0,0001, выявлены статистически значимые различия, что говорит о преимуществе ИСН в выявлении предикторов. Заключение. При малой выборке с небольшим количеством событий искусственные нейронные сети имеют преимущество над другими методиками при определении предикторов влияния на зависимую переменную.