Papillary muscle sling: a new functional approach to mitral repair in patients with ischemic left ventricular dysfunction and functional mitral regurgitation

Reverse Left Ventricular Remodeling With Transcatheter Interventions in Chronic Heart Failure Syndromes: An Updated Appraisal of the Device Landscape

Chronic heart failure (HF) is a clinical syndrome of myocardial dysfunction characterized by inadequate cardiac output or preserved output that can only be achieved by sustaining abnormal loading conditions. Morphologically, HF with reduced left ventricular function results in progressive chamber remodeling, meaning the ventricle dilates, operating at larger end-diastolic and end-systolic volumes, and takes on an abnormal, spherical shape that increases wall stress. Reverse remodeling is the goal of HF-directed therapies and can be achieved by biological means, ie, altering the loading conditions that, at a cellular level, promote myocardial dysfunction, or physical means, ie, directly altering myocardial mass or shape. In this review, we highlight the existing and emerging device-based mechanisms for biologically and physically reverse remodeling the left ventricle in chronic HF.

Description, Feasibility, and Histological Assessment of the Vsling, a Novel Transcatheter Ventricular Repair Device

Background

Reshaping the dilated left ventricle using a surgically implanted papillary muscle sling has been shown to provide long-term improvement in cardiac function compared to annuloplasty alone in patients with systolic heart failure. A papillary muscle sling which can be implanted via a transcatheter approach has the potential to make this treatment more widely available to patients.

Methods

The Vsling transcatheter papillary muscle sling device was evaluated in a chronic animal model (sacrificed at 30 and 90 days), in a simulator, and in a human cadaver.

Results

The Vsling device was successfully implanted in 10 pigs, 6 simulator procedures, and 1 human cadaver. Procedure complexity and device usability were rated as reasonable or better by 6 interventional cardiologists. Gross and histological analysis in chronic pigs through 90 days demonstrated near-complete endothelial coverage with mild inflammation and small hematoma formation but without adverse tissue reactions, thrombi, or embolization.

Conclusions

Preliminary feasibility and safety of the Vsling implant and implantation procedure have been demonstrated. Human trials are planned to begin in the summer of 2022.

Left ventricular remodeling after mitral valve repair and papillary muscle approximation

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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

Background

Undersizing 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.

Methods

An 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.

Results

FMR 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.

Conclusions

This 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.

Too much of a good thing in ischemic mitral: lessons for surgeons and cardiologists

No abstract present.

A Novel Quantitative Ex Vivo Model of Functional Mitral Regurgitation

OBJECTIVE

Durability of mitral valve (MV) repair for functional mitral regurgitation (FMR) remains suboptimal. We sought to create a highly reproducible, quantitative ex vivo model of FMR that functions as a platform to test novel repair techniques.

METHODS

Fresh swine hearts (n = 10) were pressurized with air to a left ventricular pressure of 120 mmHg. The left atrium was excised and the altered geometry of FMR was created by radially dilating the annulus and displacing the papillary muscle tips apically and radially in a calibrated fashion. This was continued in a graduated fashion until coaptation was exhausted. Imaging of the MV was performed with a 3-dimensional (3D) structured-light scanner, which records 3D structure, texture, and color. The model was validated using transesophageal echocardiography in patients with normal MVs and severe FMR.

RESULTS

Compared to controls, the anteroposterior diameter in the FMR state increased 32% and the annular area increased 35% (P < 0.001). While the anterior annular circumference remained fixed, the posterior circumference increased by 20% (P = 0.026). The annulus became more planar and the tenting height increased 56% (9 to 14 mm, P < 0.001). The median coaptation depth significantly decreased (anterior leaflet: 5 vs 2 mm; posterior leaflet: 7 vs 3 mm, P < 0.001). The ex vivo normal and FMR models had similar characteristics as clinical controls and patients with severe FMR.

CONCLUSIONS

This novel quantitative ex vivo model provides a simple, reproducible, and inexpensive benchtop representation of FMR that mimics the systolic valvular changes of patients with FMR.

Ischemic Mitral Regurgitation: A Multifaceted Syndrome with Evolving Therapies

Dysfunction of the left ventricle (LV) with impaired contractility following chronic ischemia or acute myocardial infarction (AMI) is the main cause of ischemic mitral regurgitation (IMR), leading to moderate and moderate-to-severe mitral regurgitation (MR). The site of AMI exerts a specific influence determining different patterns of adverse LV remodeling. In general, inferior-posterior AMI is more frequently associated with regional structural changes than the anterolateral one, which is associated with global adverse LV remodeling, ultimately leading to different phenotypes of IMR. In this narrative review, starting from the aforementioned categorization, we proceed to describe current knowledge regarding surgical approaches in the management of IMR.

Meta-analysis of results of subvalvular repair for severe ischemic mitral regurgitation

BACKGROUND AND AIM OF THE STUDY

The aim of this meta-analysis was to compare short- and long-term outcomes of patients undergoing mitral annuloplasty (MA) with or without papillary muscle surgery (PMS) for the treatment of ischemic mitral regurgitation (IMR).

METHODS

A systematic review and meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were performed.

RESULTS

Nine studies met the inclusion criteria. This meta-analysis identified 478 patients: 228 patients underwent MA alone and 250 patients underwent concomitant PMS. Early mortality was similar between two groups (odds ratio [OR] 1.14, 95% confidence interval [CI], 0.51-2.53; P = .75). PMS was associated at follow-up with a higher freedom from cardiac-related events (P = .050); moreover, although both surgical techniques had a positive impact on ventricular remodeling, the PMS group showed a significant higher reduction of left ventricle end-diastolic diameter (OR, 4.89, 95% CI, 2.77-7.01; P < .001) and left ventricle end-systolic diameter values (OR, 4.11, 95% CI, 1.98-6.24; P < .001). Finally, PMS compared with MA alone was associated with a significant reduction of recurrent mitral regurgitation at follow-up (OR, 3.25, 95% CI, 1.60-6.59; P = .001).

CONCLUSIONS

This meta-analysis demonstrated superiority in terms of ventricular remodeling of a combined approach encompassing PMS and MA over MA alone in IMR. Moreover, the association of subvalvular surgery with restrictive MA decreases the incidence of mitral regurgitation recurrence and cardiac-related events at follow-up.

Chirurgie bei funktioneller Mitralklappeninsuffizienz

Hintergrund

Neue Studien haben in den letzten Jahren wesentlich zum Verständnis der Behandlung der funktionellen Mitralklappeninsuffizienz (FMR) beigetragen. Dabei scheint vordergründig der interventionellen „Edge-to-edge“-Plastik die tragende Rolle zuzukommen.

Fragestellung

Welche Bedeutung hat die chirurgische Mitralklappenrekonstruktion bei FMR im Lichte der aktuellen Evidenz?

Material und Methoden

Die kritische Betrachtung aktueller Studien (CTSNet, MITRA-FR, COAPT), von Metaanalysen und neuer chirurgischer Studien zeigt Mängel der erstgenannten Studien sowie fehlendes Potenzial für Verallgemeinerungen und die Wertigkeit neuerer chirurgischer Ansätze auf.

Ergebnisse

Erstmals konnte in einer randomisierten Studie die Überlegenheit einer Klappenintervention gegenüber optimaler medikamentöser Therapie gezeigt werden. Neue chirurgische Techniken mit Einschluss subanulärer Rekonstruktionen in minimalinvasiver Technik gehen mit einer deutlich besseren Prognose für den Patienten einher als die restriktive Anuloplastie allein und als interventionelle Rekonstruktionen durch Edge-to-edge-Plastik.

Schlussfolgerung

Diese Ergebnisse verdeutlichen die Vorteile der Mitralklappenrekonstruktion in der Behandlung der FMR. Ergänzende subanuläre Rekonstruktionen bergen das Potenzial für eine anhaltende Freiheit von Mitralklappeninsuffizienz Rezidiven und klinischen Ereignissen, das die isolierte Edge-to-edge-Plastik nicht erreicht. Allein durch interdisziplinäre Diskussion im Herz-Team kann die optimale individualisierte Therapiestrategie unter Einbeziehung aller Techniken gefunden werden.

Risk of Ischemic Mitral Regurgitation Recurrence After Combined Valvular and Subvalvular Repair

BACKGROUND

Mitral valve repair (MVr) combined with papillary muscle approximation (PMA) may improve repair durability in severe ischemic mitral regurgitation (MR), when compared with MVr alone. We sought to identify preoperative transthoracic echocardiographic markers associated with MR recurrence after MVr with PMA.

METHODS

A post-hoc analysis was performed on patients with severe ischemic MR who underwent coronary artery bypass graft surgery with MVr with PMA in the papillary muscle approximation randomized trial. The PMA was performed utilizing a 4-mm polytetrafluoroethylene graft placed around the papillary muscles. Linear regression analyses and receiver-operating characteristic curves were used to identify echocardiographic variables and diagnostic models associated with recurrent MR.

RESULTS

There were 48 patients with a mean age of 63 ± 7 years, a left ventricular ejection fraction of 35% ± 5%, and a left ventricular end-diastolic diameter of 63 ± 3 mm. Of these, 37 patients had baseline and 5-year follow-up echocardiograms, with moderate-to-severe MR recurring in 27%. Linear regression analyses revealed associations between preoperative pulmonary artery systolic pressure (standardized beta coefficient, β = 0.49/mm Hg, p = 0.002), MV tenting area (β = 0.47/cm2, p = 0.004), a symmetric MV tethering pattern (β = 0.44, p = 0.007), and left ventricular end-diastolic diameter (β = 0.37/mm, p = 0.02) with follow-up MR grade. The presence of both MV tenting area 3.1 cm2 or greater (area under the curve 0.822) and left ventricular end-diastolic diameter of 64 mm or greater (area under the curve 0.801) was the most robust discriminative model for moderate-to-severe MR recurrence (specificity 92%, sensitivity 69%, area under the curve 0.804, p = 0.003).

CONCLUSIONS

In patients undergoing coronary artery bypass graft surgery with MVr plus PMA, the extent of baseline MV apparatus and left ventricle geometric remodeling identifies patients at increased risk for MR recurrence.

The unique mechanism of functional mitral regurgitation in acute myocardial infarction: a prospective dynamic 4D quantitative echocardiographic study

AIMS

Mechanisms of chronic ischaemic mitral regurgitation (IMR) are well-characterized by apically tethered leaflet caused by papillary muscles (PMs) displacement and adynamic mitral apparatus. We investigated the unique geometry and dynamics of the mitral apparatus in first acute myocardial infarction (MI) by using quantified 3D echocardiography.

METHODS AND RESULTS

We prospectively performed 3D echocardiography 2.3 ± 1.8 days after first MI, in 174 matched patients with (n = 87) and without IMR (n = 87). 3D echocardiography of left ventricular (LV) volumes and of mitral apparatus dynamics throughout cardiac cycle was quantified. Similar mitral quantification was obtained at chronic post-MI stage (n = 44). Mechanistically, acute IMR was associated with larger and flatter annulus (area 9.29 ± 1.74 cm2 vs. 8.57 ± 1.94 cm2, P = 0.002, saddle shape 12.7 ± 4.5% vs. 15.0 ± 4.6%, P = 0.001), and larger tenting (length 6.36 ± 1.78 mm vs. 5.60 ± 1.55 mm, P = 0.003) but vs. chronic MI, mitral apparatus displayed smaller alterations (all P < 0.01) and annular size, PM movement remained dynamic (all P < 0.01). Specific to acute IMR, without PM apical displacement (P > 0.70), greater separation (21.7 ± 4.9 mm vs. 20.0 ± 3.4 mm, P = 0.01), and widest angulation of PM (38.4 ± 6.2° for moderate vs. 33.5 ± 7.3° for mild vs. 31.4 ± 6.3° for no-IMR, P = 0.0009) wider vs. chronic MI (P < 0.01).

CONCLUSIONS

3D echocardiography of patients with first MI provides insights into unique 4D dynamics of the mitral apparatus in acute IMR. Mitral apparatus remained dynamic in acute MI and distinct IMR mechanism in acute MI is not PM displacement seen in chronic IMR but separation and excess angulation of PM deforming the mitral valve, probably because of sudden-onset regional wall motion abnormality without apparent global LV remodelling. This specific mechanism should be considered in novel therapeutic strategies for IMR complicating acute MI.

Clinical manifestations, diagnosis, and treatment of ischemic mitral regurgitation: a review

Ischemic mitral regurgitation (IMR) is a frequent complication after acute myocardial infarction (AMI) associated with a worse prognosis. The pathophysiological mechanisms of IMR are not fully understood, but it is known to be a complex process in which ventricular remodelling is the main causal factor. The various imaging techniques in cardiology and echocardiography fundamentally have contributed significantly to clarify the mechanisms that cause and progressively aggravate IMR. At present, different therapeutic options, the most important of which are cardio-surgical, address this problem. Nowadays the improvement in cardiac surgery and transcatheter therapies, have shown a therapeutic advance in IMR management. IMR is a predictor of poor prognosis in patients with heart failure and depressed left ventricular (LV) systolic function. However, it remains controversial whether mitral regurgitation (MR) in these patients is a consequence of dilation and dysfunction of the LV, or whether it contributes to worsening the prognosis of the ventricular dysfunction. Given that echocardiography has a fundamental reference role in the identification, graduation of severity and evaluation of the therapeutics used in the treatment of MR, we are going to focus on it over the rest of the imaging techniques. In contrast to primary MR the benefits of mitral surgery in patients with secondary MR are uncertain. Therefore, we will comment fundamentally on the role of mitral surgery in patients with IMR, with an update of the different surgical interventions available, without forgetting to mention the other therapeutic options currently available.

Functional mitral regurgitation: an overview for surgical management framework

Functional mitral regurgitation (FMR) is one the most common complications of myocardial infarction (MI) in adults carrying a significant clinical and economic burden. Despite specific randomized controlled studies to address its treatment have been performed, there are still a number of questions remained unanswered. Outcomes of surgical repair of FMR are still hampered by a significant rate of recurrence of regurgitation and need for reoperation. Mechanisms underlying failure of repairs still need to be completely clarified and questions regarding the indications and optimal timing for intervention as well as the best suitable operative technique to be applied are still debated. This work will review the current knowledge on FMR including its pathogenic mechanisms, the available treatment strategies, the evidences from trials and observational studies and the potential future directions to address the issues related to its treatment.

Mitral Valve and Subvalvular Repair for Secondary Mitral Regurgitation: Rationale and Clinical Outcomes of the Papillary Muscle Sling

Secondary mitral regurgitation (MR) is a common finding in patients with dilated cardiomyopathy, and it is associated with poor outcomes. It is the result of incomplete systolic closure of the mitral valve (MV) as a consequence of left ventricular dilatation, papillary muscle displacement with impaired systolic shortening, and mitral leaflet tethering. MV surgery may be performed in cases of significant secondary MR despite guideline-directed medical therapy. However, MV repair, which is most commonly performed with an undersized ring annuloplasty, is associated with a 30-60% recurrence of moderate or greater MR at mid-term follow-up. To improve MV repair durability, several adjunctive subvalvular procedures have been proposed, one of which is the addition of papillary muscle approximation utilizing a papillary muscle sling. Recent studies comparing the outcomes of a conventional undersized ring annuloplasty with a MV repair utilizing a papillary muscle sling have reported a significant reduction in recurrent moderate or severe MR, greater left ventricular reverse remodeling, and improved MV apparatus geometry with the addition of the papillary muscle sling. We present a comprehensive review of the pathophysiology of secondary MR, and the rationale and clinical outcomes of MV repair with papillary muscle sling placement for the treatment of secondary MR.

Application of polymer-mesh device to remodel left ventricular-mitral valve apparatus in ischemic mitral regurgitation

OBJECTIVES

Ischemic mitral regurgitation (IMR) results from ischemic left ventricular (LV) distortion and remodeling, which displaces the papillary muscles and tethers the mitral valve leaflets apically. The aim of this experimental study was to examine efficacy of an adjustable novel polymer filled mesh (poly-mesh) device to reverse LV remodeling and reduce IMR.

METHODS

Acute (N = 8) and chronic (8 weeks; N = 5) sheep models of IMR were studied. IMR was produced by ligation of circumflex branches to create myocardial infarction. An adjustable poly-mesh device was attached to infarcted myocardium in acute and chronic IMR models and compared with untreated sham sheep. Two- and 3-dimensional echocardiography and hemodynamic measurements were performed at baseline, post IMR, and post poly-mesh (humanely killed).

RESULTS

In acute models, moderate IMR developed in all sheep and decreased to trace/mild (vena contracta: 0.50 ± 0.09 cm to 0.26 ± 0.12 cm; P < .01) after poly-mesh. In chronic models, IMR decreased in all sheep after poly-mesh, and this reduction persisted over 8 weeks (vena contracta: 0.42 ± 0.09 cm to 0.08 ± 0.12 cm; P < .01) with significant increase in the slope of end-systolic pressure-volume relationship (1.1 ± 0.5 mm Hg/mL to 2.9 ± 0.7 mm Hg/mL; P < .05). There was a significant reduction in LV volumes from chronic IMR to euthanasia stage with poly-mesh compared with sham group (%end-diastolic volume change -20 ± 11 vs 15% ± 16%, P < .01; %end-systolic volume change -14% ± 19% vs 22% ± 22%, P < .05; poly-mesh vs sham group) consistent with reverse remodeling.

CONCLUSIONS

An adjustable polymer filled mesh device reduces IMR and prevents continued LV remodeling during chronic follow-up.

Comparison of mitral competence after mitral repair with papillary muscle approximation versus papillary muscle relocation for functional mitral regurgitation

The purpose of this study was to evaluate the surgical results of papillary muscle approximation (PMA) and papillary muscle relocation (PMR) for functional mitral regurgitation (FMR) and to compare the effects of both procedures on the change in mitral regurgitation (MR) and echocardiogram parameters associated with tethering. Eighteen patients with moderate-to-severe FMR (MR grade ≥2) who underwent PMA or PMR were retrospectively analyzed. Underlying diseases were ischemic cardiomyopathy, idiopathic dilated cardiomyopathy, and aortic valve disease for seven, six, and five patients, respectively. Eleven patients underwent PMA and seven patients underwent PMR. Mitral annuloplasty and surgical ventricular restoration were performed concomitantly for 18 and 6 patients, respectively. None of these patients died in the hospital. Three patients died during the late period; two of these deaths were cardiac related. The rate of 3 years of freedom from cardiac-related death was 89%. After a mean follow-up of 33 months, MR grade was significantly improved compared with preoperative values (3.0 ± 0.8 to 0.7 ± 1.2; p < 0.01). Recurrence of MR grade ≥2 occurred in three patients and the rate of 3 years of freedom from recurrence of MR grade ≥2 was 87%. During follow-up, tenting height (1.1 ± 0.2 to 0.7 ± 0.2 cm; p < 0.01), tenting area (2.2 ± 0.7 to 0.9 ± 0.5 cm²; p < 0.01), and anterior leaflet tethering angle (39° ± 11° to 26° ± 8°; p < 0.01) were significantly improved compared with preoperative values. Posterior leaflet tethering angle significantly deteriorated from 40° ± 7° to 53° ± 15° (p < 0.01); however, it did not further deteriorate compared with the early postoperative value of 55° ± 16° (p = 0.7). There was no difference in echocardiogram parameters associated with tethering between PMA and PMR throughout the observation period. Both methods were associated with lasting relief of MR and reverse left ventricular remodeling. There was no difference between PMA and PMR regarding the effect on mitral valve competence. Both methods allowed durable mitral repair and good clinical outcomes.

Analysing the reasons of failure of surgical mitral repair approaches-do we need to better think in biomechanics?

The failure of mitral valve repair procedures revealed in the outcomes of the recent randomized studies is suggesting the necessity for a better understanding of the biomechanical mechanisms underlying the failure of the surgical approaches. Use of biomechanical modelling and finite element analysis (FEA) in cardiovascular research is an important aid in this context. In our group we developed a biomechanical model taking into account all the component of the mitral valve functional unit including the valve leaflets, the annulus, the papillary muscles, the chordae tendinea and the ventricular geometry. The two-dimensional mathematical model was capable to predict some of the actual geometrical and mechanical features of the valvular and subvalvular apparatuses in physiological and pathological conditions providing the engineering quantitative relations between closing and tethering forces and the mechanisms governing the mitral valve unit function. This model might further become patient-specific by means of 3D reconstruction of clinical imaging. Images are first converted in a standard vector format (DICOM, etc.), then automatically translated in a "structural" finite element model and finally implemented in a finite element code. This allows for in silico simulations to virtually explore the effects of different surgical approaches at an early stage after the procedure, to help the operative decision processes, or to optimize the design of surgical implants.

Mitral valve repair and subvalvular intervention for secondary mitral regurgitation: a systematic review and meta-analysis of randomized controlled and propensity matched studies

BACKGROUND

Combining a ring annuloplasty (Ring) with a mitral subvalvular intervention (Ring + subvalvular) in patients with secondary mitral regurgitation (MR) may improve mitral valve (MV) repair durability. However, the outcomes of this strategy compared with a Ring only, have not been clearly defined.

METHODS

A systematic review and meta-analysis was performed utilizing randomized controlled and propensity matched studies which compared a Ring + subvalvular versus Ring MV repair for the treatment of secondary MR. Risk ratio (RR), weighted mean difference (MD), and the 95% confidence interval (CI) were calculated by the Mantel-Haenszel and inverse-variance methods, for clinical outcomes and echocardiographic measures of follow-up MR, left ventricular (LV) reverse remodeling, and MV apparatus geometry.

RESULTS

Five studies were identified, with a total of 397 patients. Baseline characteristics were similar between groups, and all patients had moderate to severe secondary MR, with the vast majority in the setting of ischemic cardiomyopathy. A Ring + subvalvular repair consisted of papillary muscle approximation (n=2), papillary muscle relocation (n=2), or secondary chordal cutting (n=1). Follow-up ranged from 10.1 (mean range =0.25-42) to 69 [interquartile range (IQR) =23-82] months. When compared with Ring only at last follow-up, a Ring + subvalvular MV repair was associated with: (I) a smaller MR grade (MD =-0.44, 95% CI -0.69 to -0.19; P=0.0005); (II) a reduced risk of moderate or greater recurrent MR (RR =0.43, 95% CI, 0.27-0.66; P=0.0002); (III) a smaller mean LV end-diastolic diameter (MD =-3.56 mm, 95% CI -5.40 to -1.73; P=0.0001) and a greater ejection fraction (MD =2.64%, 95% CI, 0.13-5.15; P=0.04); and, (IV) an improved MV apparatus geometry. There were no differences in operative mortality, post-operative morbidity, or follow-up survival between surgical approaches.

CONCLUSIONS

When compared with Ring only, a Ring + subvalvular MV repair is associated with greater LV reverse remodeling and systolic function, less recurrence of moderate or greater MR, and an improved geometry of the MV apparatus at short and mid-term follow-up.

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.

The role of papillary muscle approximation in mitral valve repair for the treatment of secondary mitral regurgitation

Secondary mitral regurgitation (MR) is present in up to half of patients with dilated cardiomyopathy, and is associated with a poor prognosis. It primarily results from progressive left ventricular remodelling, papillary muscle displacement and tethering of the mitral valve leaflets. Mitral valve repair with an undersized ring annuloplasty is the reparative procedure of choice in the treatment of secondary MR. However, this technique is associated with a 30-60% incidence of recurrent moderate or greater MR at mid-term follow-up, which results in progressive deterioration of left ventricular function and increased morbidity. Combined mitral valve repair and papillary muscle approximation has been applied in order to address both the annular and subvalvular dysfunction that coexist in secondary MR, which include graft and suture-based techniques. Herein, we provide a systematic review of the published literature regarding the technical aspects, clinical application, and outcomes of mitral valve repair with combined ring annuloplasty and papillary muscle approximation for the treatment of secondary MR.

Management of Tricuspid Regurgitation in Patients With Hypoplastic Left Heart Syndrome

Tricuspid valve (TV) performance is critical for palliation of hypoplastic left heart syndrome. We will review current TV repair techniques, outcomes, and novel approaches.

Ischemic mitral valve prolapse

Ischemic mitral prolapse (IMP) is a pathologic entity encountered in about one-third among the patients undergoing surgery for ischemic mitral regurgitation (IMR). IMP is generally the result of a papillary muscle injury consequent to myocardial, but the recent literature is progressively unveiling a more complex pathogenesis. The mechanisms underlying its development regards the impairment of one or more components of the mitral apparatus, which comprises the annulus, the chordae tendineae, the papillary muscle and the left ventricular wall. IMP is not only a disorder of valvular function, but also entails coexistent aspects of a geometric disturbance of the mitral valve configuration and of the left ventricular function and dimension and a correct understanding of all these aspects is crucial to guide and tailor the correct therapeutic strategy to be adopted. Localization of prolapse, anatomic features of the prolapsed leaflets and the subvalvular apparatus should be carefully evaluated as also constituting the major determinants defining patient's outcomes. This review will summarize our current understanding of the pathophysiology and clinical evidence on IMP with a particular focus on the surgical treatment.

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

BACKGROUND

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.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Is subvalvular repair worthwhile in severe ischemic mitral regurgitation? Subanalysis of the Papillary Muscle Approximation trial

OBJECTIVE

The symmetry of mitral valve tethering and regional left ventricle wall dysfunction are reported to play a fundamental role in the outcomes and long-term durability of surgical repair in ischemic mitral regurgitation (IMR). We recently demonstrated in a randomized clinical trial (the Papillary Muscle Approximation trial) the superiority of papillary muscle approximation (PMA) in combination with standard restrictive annuloplasty (RA) in severe IMR over annuloplasty alone in terms of adverse left ventricular remodeling and mitral regurgitation (MR) recurrence. This approach, however, failed to produce a survival advantage and was still plagued by a high incidence of reoperation. We therefore performed a subanalysis of the PMA trial on the basis of preoperative parameters to elucidate the value of subvalvular surgery in certain subcategories of patients with the aim of creating a decisional algorithm on the best operative strategy.

METHODS

We performed a subanalysis of PMA trial, evaluating 96 patients with severe IMR and eligible for myocardial revascularization randomized to PMA + RA (n = 48) versus RA alone (n = 48) in association with coronary artery bypass grafting. Endpoints included left ventricular remodeling, MR recurrence, overall mortality, reoperation, and a composite cardiac endpoint (cardiac death, stroke, reintervention, hospitalization for heart failure, or New York Heart Association class worsening). Stratification variables were preoperative symmetry of mitral valve tethering and regional wall motion abnormality.

RESULTS

PMA improved ventricular remodeling and recurrence of MR in both preoperative symmetric and asymmetric tethering and in case of inferior wall dyskinesia but did not produce an additional benefit in anterolateral wall dysfunction.

CONCLUSIONS

Preoperative symmetric and asymmetric tethering and isolated inferior wall dyskinesia are an indication for subvalvular apparatus surgery in IMR.

Mid-term results of mitral valve repair for ischemic mitral regurgitation with ETlogix ring: A single-center study

BACKGROUND

Ischemic mitral regurgitation (IMR) is a common complication of coronary artery disease and represents an independent predictor of mortality. In the IMR the pattern of mitral valve annular dilatation is asymmetrical: this can explain the long-term incidence of recurrent mitral regurgitation after surgical annular size reduction with a symmetrical ring. The aim of this study is to analyze early and mid-term results of mitral valve repair (MVR) with the CMA IMR ETlogix ring, specifically developed for the surgical correction of IMR.

METHODS

Retrospectively, we studied 157 consecutive patients who underwent MVR with the CMA ETlogix ring for the treatment of grade ≥2 IMR in our center between June 2006 and December 2012. We reported clinical and echocardiographic early and mid-term results of this surgical technique.

RESULTS

Postoperative 30days mortality was 6.3%. Postoperative echocardiography evaluation at discharge revealed the absence of residual MR in 70%, mild MR in 26.5% and moderate MR in 3.5% of patients respectively. Median echographic follow-up time was 28 (3-84) months: survival rate was 92.1% at 32months; free from mitral valve reoperation rate was 97.5% and grade >2 MR recurrence free survival rate was 96.6%.

CONCLUSION

There are a few reports in the literature concerning the mid-term results of IMR surgical correction with CMA Etlogix ring. Our study, taking into account a large series of patients and an important follow-up period, demonstrates the effectiveness of this surgical repair technique reporting a low mid-term incidence of recurrent MR.

Papillary Muscle Approximation Versus Restrictive Annuloplasty Alone for Severe Ischemic Mitral Regurgitation

BACKGROUND

Guidelines recommend surgery for patients with severe ischemic mitral regurgitation (MR). Nonrandomized studies suggest that subvalvular repair is associated with longer survival, but randomized studies are lacking.

OBJECTIVES

This study sought to investigate the benefit of papillary muscle surgery on long-term clinical outcomes of patients with ischemic MR.

METHODS

Ninety-six patients with severe ischemic MR were randomized to either undersizing restrictive mitral annuloplasty (RA) or papillary muscle approximation with undersizing restrictive mitral annuloplasty (PMA) associated with complete surgical myocardial revascularization. The primary endpoint was change in left ventricular end-diastolic diameter (LVEDD) after 5 years, measured as the absolute difference from baseline, which was evaluated by paired Student t tests. Secondary endpoints included changes in echocardiographic parameters, overall mortality, the composite cardiac endpoint (major adverse cardiac and cerebrovascular events [MACCE]), and quality of life (QOL) during the 5-year follow-up.

RESULTS

At 5 years, mean LVEDD was 56.5 ± 5.7 mm with PMA versus 60.6 ± 4.6 mm with RA (mean change from baseline -5.8 ± 4.1 mm and -0.2 ± 2.3 mm, respectively; p < 0.001). Ejection fraction was 44.1 ± 6% in the PMA group versus 39.9 ± 3.9% in the RA group (mean change from baseline 8.8 ± 5.9% and 2.5 ± 4.3%, respectively; p < 0.001). There was no statistically significant difference in mortality at 5 years, but freedom from MACCE favored PMA in the last year of follow-up. PMA significantly reduced tenting height, tenting area, and interpapillary distance soon after surgery and for the long-term, and significantly lowered moderate-to-severe MR recurrence. No differences were found in QOL measures.

CONCLUSIONS

Compared with RA only, PMA exerted a long-term beneficial effect on left ventricular remodeling and more effectively restored the mitral valve geometric configuration in ischemic MR, which improved long-term cardiac outcomes, but did not produce differences in overall mortality and QOL.

Early Results of a Novel Mitral Valve Repair Procedure: The Interpapillary Polytetrafluoroethylene Bridge Formation

BACKGROUND

Surgical repair of ischemic mitral regurgitation (IMR) associated with chordal rupture in patients with ischemic cardiomyopathy is challenging as it aims to correct several structural pathologies at once. There are ongoing studies evaluating multiple approaches, however long term results are still scarce.

METHODS AND RESULTS

19 patients with IMR underwent mitral valve repair with interpapillary polytetrafluoroethylene (PTFE) bridge and neochordae formation at the Zala County Teaching Hospital. Concomitant coronary artery bypass grafting was performed in all patients. Post-procedural Transesophageal Echocardiogram (TEE) showed no mitral regurgitation (MR) in eighteen (94.7%) patients, with a leaflet coaptation mean height of 8 ± 3 mm. No operative mortality was observed. At the follow up (mean 17.7 ± 4.6 months; range 9 to 24 months), 17 (89%) patients showed no leakage and 2 had regurgitation grade ≤1, with documented NYHA functional class I or II in all patients.

CONCLUSION

This retrospective study presents the first results of a novel surgical approach to treating ischemic mitral regurgitation. The interpapillary PTFE bridge formation is a safe and feasible surgical procedure that is reproducible, time sparing and effectively eliminates mitral valve regurgitation with promising long-term results.

Double row of overlapping sutures for downsizing annuloplasty decreases the risk of residual regurgitation in ischaemic mitral valve repair

OBJECTIVES

The aim of this study was to evaluate a novel insertion technique of the prosthetic ring that would further magnify the degree of annulus narrowing, thereby reducing the potential for a residual leak in ischaemic mitral valve repair.

METHODS

Thirty-six patients with ischaemic mitral regurgitation (MR) were randomly assigned into two groups. In 18 patients, the prosthetic ring was inserted in the conventional manner with a single row of sutures (control group). In the remaining 18 patients, the ring was attached using a double row of sutures tied both on the inner and on the outer part of the sewing cuff. Both groups had similar preoperative clinical and echocardiographic characteristics with severe leaflet tethering: mean tenting area >2.5 cm(2), mean anterior leaflet angle >25° and posterior leaflet angle >45°. The mean prosthetic ring sizes inserted in both groups were identical (mean: 27.3 mm).

RESULTS

At 12 months, there was no clinical event except for 1 rehospitalization in the control group. The mean mitral regurgitation grade was higher in the control group than in the group with the double row of sutures at 1.6 ± 0.9 vs 0.7 ± 0.3 (P = 0.0003). Annulus diameter reduction was less pronounced in the control group when compared with the group with the double row of sutures, both in the parasternal long-axis: 29.3 ± 3 vs 26.3 ± 3 mm (P = 0.0003) and in apical four-chamber views: 31 ± 3 vs 28 ± 2 mm (P = 0.003). Leaflet tethering indices were greater in the control group than in the group with the double row of sutures: tenting area: 1.42 ± 0.3 vs 1.1 ± 0.5 cm(2) (P = 0.002), anterior leaflet angle: 33 ± 3° vs 28 ± 5° (P = 0.0009) and posterior leaflet angle: 110 ± 13° vs 80 ± 11° (P = 0.0001). Left ventricular function parameters were not statistically different among the two groups.

CONCLUSION

A double row of overlapping sutures for attaching the prosthetic ring in downsizing annuloplasty is more efficient in narrowing the mitral annulus than the conventional technique in ischaemic mitral repair. Even in high-risk patients whose leaflets were severely tethered on echocardiography, it almost eliminated the risk of MR recurrence in this study.

Mitral valve repair over five decades

It has become evident that mitral valve (MV) repair is the preferable treatment for the majority of patients presenting with severe mitral regurgitation (MR). This success clearly testifies that the surgical procedure is accessible, reproducible and is carrying excellent long-lasting results. From the pre-extracorporeal circulation's era to the last percutaneous approaches, a large variety of techniques have been proposed to address the different features of MV diseases. This article aimed at reviewing chronologically the development of these dedicated techniques through their origins and the debates that they generated in the literature.

A novel coaptation plate device for functional mitral regurgitation: an in vitro study

A novel mitral valve repair device, coaptation plate (CP), was proposed to treat functional mitral regurgitation. The objective of this study was to test efficacy of the CP in an in vitro model of functional mitral regurgitation. Ten fresh porcine mitral valves were mounted in a left heart simulator, Mitral regurgitation was emulated by means of annular dilatation, and the asymmetrical or symmetrical papillary muscles (PM) displacement. A rigid and an elastic CPs were fabricated and mounted in the orifice of regurgitant mitral valves. Steady flow leakage in a hydrostatic condition and regurgitant volume in a pulsatile flow were measured before and after implantation of the CPs. The rigid and elastic CPs reduced mitral valve regurgitant volume fraction from 60.5 ± 11.4 to 35 ± 11.6 and 36.5 ± 9.9%, respectively, in the asymmetric PM displacement. Mitral regurgitation was much lower in the symmetric PM displacement than in the asymmetric PM displacement, and was not significantly reduced after implantation of either CP. In conclusion, both the rigid and elastic CPs are effective and have no difference in reduction of functional mitral regurgitation. The CP does not aggravate mitral valve coaptation and may be used as a preventive way.

Morphological study of chordae tendinae in human cadaveric hearts

Objectives:

The chordae tendinae (CT) are strong, fibrous connections between the valve leaflets and the papillary muscles. Dysfunction of the papillary muscles and chordae is frequent. Mitral valve replacement with preservation of CT and papillary muscles may preserve postoperative left ventricular function better than conventional mitral valve replacement in patients with chronic mitral regurgitation.

Methods:

The study was carried out on 116 human cadaveric hearts. The heart was opened through the atrioventricular valve to view the constituents of the complex. Origin, attachments, insertions, distribution, branching pattern and gross structure of CT were observed and studied in detail.

Results:

In the present study more than 21 terminologies of CT were defined by classifying it into six different types. Classification is done according to the origin, attachments, insertion, distribution, branching pattern and gross structure. Terminologies defined are as follows. Apical pillar chordae, Basal pillar chordae, True chordae, False chordae, Interpillar chordae, Pillar wall chordae, Cusp chordae, Cleft chordae, Commissural chordae, First order chordae, Second order chordae, Free zone chordae, Marginal chordae, Rough zone chordae, Straight chordae, Branched-fan shaped chordae, Spiral chordae, Irregular-web chordae, Tendinous chordae, Muscular chordae, Membranous chordae. Basal pillar chordae are found in 9.48%. Mean number of chordae taking origin from apical half of a single papillary muscle or single head of papillary muscle was 9.09 with the range of 3-18. Mean number of the marginal chordae attached to a single cusp was 22.63 ranging from 11 to 35. Strut chordae showed interesting insertion with broad aponeurosis in 38.79% and large muscular flaps in 13.79%. Chordae muscularis were found in 14% and membranous chordae were found in 6%.

Conclusions:

This knowledge may prove useful for cardiologists and cardiac surgeons.

Surgical strategy for ischemic mitral regurgitation adopting subvalvular and ventricular procedures

PURPOSE

The progression of left ventricular (LV) remodeling and subsequent mitral valve tethering impair the results of reduction annuloplasty for ischemic mitral regurgitation (MR).

METHODS

We studied 90 patients who underwent surgical repair of ischemic MR between 1999 and 2013 according to our surgical strategy adding submitral and ventricular procedures to annuloplasty as follows: annuloplasty alone (stage 1, n = 30), additional papillary muscle approximation (PMA) for progression of tethering (stage 2, n = 26), and additional left ventriculoplasty with PMA for progression of LV remodeling and tethering (stage 3, n = 34).

RESULTS

The preoperative New York Heart Association (NYHA) functional classes (2.5 ± 0.7, 3.1 ± 0.7 and 3.3 ± 0.7 for stages 1, 2 and 3, respectively, P <0.001), LV end-diastolic diameters (56 ± 7 mm, 66 ± 5 mm and 70 ± 7 mm, P <0.001), and LV ejection fractions (45 ± 12%, 32 ± 9% and 27 ± 9%, P <0.001) significantly differed among the stages. In contrast, the MR grades did not significantly differ (2.9 ± 0.8, 3.0 ± 1.0, and 2.9 ± 1.1, respectively; P = 0.93). Both the rates of cardiac-related survival and freedom from reoperation were comparable among the 3 groups (log-rank P = 0.92 and 0.58, respectively).

CONCLUSION

Additional submitral and ventricular procedures can compensate for the possible impairment of the outcomes after annuloplasty alone for ischemic MR in patients with severe LV remodeling and tethering.

Visualization and measurement of mitral valve chordae tendineae using three-dimensional transesophageal echocardiography from the transgastric approach

BACKGROUND

The evaluation of the submitral apparatus is challenging from the conventional transesophageal approach. The aim of this study was to test the feasibility of using three-dimensional (3D) transesophageal echocardiographic (TEE) imaging from the transgastric approach to visualize the submitral apparatus and quantify the lengths of the chordae tendineae by using multiplanar reconstruction analysis.

METHODS

Twenty-two patients who had transgastric full-volume 3D TEE data sets before mitral valve surgery underwent surgical measurement of chordal length. A short-axis plane at the chordal level was extracted from the 3D data set to identify leaflet segments and the corresponding primary chords. Then, for each chord, the optimal plane was selected to visualize and measure the entire chordal length from its origin at the leaflet margin to the papillary muscle tips. Measurements were performed at the phase of the cardiac cycle when chordal length reached its maximum. Measured values were compared with surgical measurements using linear regression and Bland-Altman analyses.

RESULT

One hundred forty-six primary chords were measured intraoperatively. Three-dimensional TEE imaging was able to measure the lengths of all these chords. The surgical and 3D TEE measurements (mean, 1.96 ± 0.56 vs 1.93 ± 0.50 cm, respectively) correlated highly (r = 0.93, P < .0001), with a minimal bias of 0.03 cm and narrow limits of agreement from -0.39 to 0.45 cm.

CONCLUSION

Transgastric 3D TEE imaging of the submitral apparatus allows visualization and accurate measurement of chordae tendineae lengths, which may be useful for planning mitral valve repair, including percutaneous transcatheter procedures.

Surgical management of moderate ischemic mitral valve regurgitation: Where do we stand?

Ischemic mitral regurgitation (IMR) represents a common complication after myocardial infarction. The valve is anatomically normal and the incompetence is the result of papillary muscles displacement and annular dilatation, causing leaflets tethering. Functionally the leaflets present a restricted systolic motion due to tethering forces that displaces the coaptation surface toward the left ventricle apex. The patients present poor left ventricular function at the time of surgery and the severity of the mitral regurgitation increases the risk of mortality. Currently there is general agreement to treat surgically severe IMR nevertheless strong evidences for patient with moderate insufficiency remains poor and proper treatment debated. The most effective surgical approach for the treatment of IMR remains debated. Some authors demonstrated that coronary artery bypass graft (CABG) alone is beneficial in patients with IMR. Conversely, in most patients, moderate IMR will persist or worsen after CABG alone which translate in higher long-term mortality as a function of residual mitral regurgitation severity. A probable reason for this unclear surgical management of functional MR is due to the contemporary suboptimal results of reparative techniques. The standard surgical treatment of chronic IMR is CABG associated with undersized annuloplasty using complete ring. Though, the recurrence of mitral regurgitation remains high (> 30%) because of continous left ventricle remodeling. To get better long term results, in the last decade, several subvalvular procedures in adjunct to mitral anuloplasty have been developed. Among them, surgical papillary muscle relocation represents the most appreciated option capable to restore normal left ventricle geometry. In the next future new preoperative predictors of increased mitral regurgitation recurrence are certainly needed to find an individual time period of treatment in each patient with moderate IMR.