RING plus STRING: papillary muscle repositioning as an adjunctive repair technique for ischemic mitral regurgitation

Mitral valve repair with papillary muscle repositioning for functional mitral regurgitation (Type IIIb) with metal allergies: a case report

Background

Prosthetic heart valves, rings, and clips commonly used in heart surgery may contain metals, such as nickel and cobalt, that can cause severe hypersensitivity reactions in allergic patients. These reactions can cause paravalvular leakage and valve dysfunction. Similarly, stainless steel sternal wires can cause contact dermatitis. We should select rings, valves, and wires that do not contain any metals known to cause allergies in patients undergoing cardiac surgery.

Case summary

We report the case of a 79-year-old man with severe functional mitral regurgitation (Type IIIb) and a history of nickel and cobalt allergies. We safely performed mitral valve repair with papillary muscle repositioning with nickel- and cobalt-free rings in this patient. He was discharged from the hospital on the 26th postoperative day without dialysis intervention. Two years after surgery, mitral and tricuspid regurgitation had not worsened.

Discussion

According to the 2020 American Heart Association guidelines, surgery for severe functional mitral valve insufficiency (Type IIIb) is considered class IIb. Meanwhile, transcatheter edge-to-edge repair is class IIa. Long-term regurgitation is difficult to control with valve replacement and annuloplasty alone; recurrence has been observed. Therefore, additional techniques were considered. Papillary muscle repositioning has been reported and shown good results. The method used in the present case made intervening in the subvalvular tissue easy and demonstrated technical feasibility, safety, and effectiveness.

Bilateral papillary muscle repositioning: successful repair of functional mitral regurgitation in dilative cardiomyopathy

OBJECTIVES

Functional mitral regurgitation (FMR) in patients with non-ischaemic dilative cardiomyopathy (DCM) is associated with heart failure and poor outcome. Aggressively undersized annuloplasty as an annular solution for a ventricular problem ameliorates heart failure but may be associated with recurrent FMR and does not improve survival. We sought to analyse if moderately undersized annuloplasty with repositioning of both papillary muscles can lead to improved valve stability and outcome in patients with DCM and FMR.

METHODS

In 66 patients with DCM-associated FMR (age 66 ± 12 years, ejection fraction 29 ± 6% and mean pulmonary artery pressure 35 ± 11 mmHg) and severe leaflet tethering (tenting height ≥10 mm) bilateral papillary muscle repositioning was added to moderately undersized ring annuloplasty (median size 30 mm). Concomitant surgery included tricuspid valve repair in 86% of patients and atrial ablation in 44%.

RESULTS

The early mortality rate was 9%. Overall 5-year freedom from all-cause death, left ventricular assist device implantation or heart transplant was 58% (95% confidence interval 45-71%). Six patients underwent reoperation (redo repair n = 4). Reverse remodelling was observed during follow-up in 66% of patients with decreasing left ventricular end-diastolic diameters (66 ± 5 to 61 ± 12 mm; P < 0.001) and left ventricular end-systolic diameters (56 ± 9 to 51 ± 14 mm; P = 0.001). Subgroup analyses (partial versus complete ring, preoperative left ventricular end-diastolic diameters <65 mm vs left ventricular end-diastolic diameter ≥65 mm) documented similar survival rates. A competing risks regression analysis identified cerebral vascular disease (P = 0.01), use of a partial ring (P = 0.03) and absence of tricuspid valve repair (P = 0.03) as independent predictors of death.

CONCLUSIONS

The combination of bilateral papillary muscle repositioning and moderately undersized ring annuloplasty leads to stable mid-term repair results and reverse remodelling in patients with DCM and FMR and severe leaflet tethering.

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.

Mitral regurgitation: anatomy is destiny

Mitral regurgitation (MR) occurs when any of the valve and ventricular mitral apparatus components are disturbed. As MR progresses, left ventricular remodelling occurs, ultimately causing heart failure when the enlarging left ventricle (LV) loses its conical shape and becomes globular. Heart failure and lethal ventricular arrhythmias may develop if the left ventricular end-systolic volume index exceeds 55 ml/m2. These adverse changes persist despite satisfactory correction of the annular component of MR. Our goal was to describe this process and summarize evolving interventions that reduce the volume of the left ventricle and rebuild its elliptical shape. This 'valve/ventricle' approach addresses the spherical ventricular culprit and offsets the limits of treating MR by correcting only its annular component.

Minimally Invasive Mitral Valve Annuloplasty With Realignment of Both Papillary Muscles for Correction of Type IIIb Functional Mitral Regurgitation

OBJECTIVE

Pathophysiological background of type IIIb functional mitral regurgitation (FMR) is a progressively increasing distance between papillary muscle tips and mitral annular plane. Standard surgical treatment of such FMR by means of undersized mitral annuloplasty is associated with a high recurrence rate.

METHODS

We propose a modified subannular maneuver to correct type IIIb FMR while combining undersized annuloplasty with a controlled realignment of both papillary muscles, thereby fixing the distance between mitral annular plane and papillary muscle tips. The differences of this subannular maneuver as compared with the previously published techniques are the following: (1) controlled realignment of both papillary muscles, (2) fixation of the papillary muscles to mitral annulus distance on an annuloplasty ring, and (3) application in a three-dimensional endoscopic minithoracotomy setting.

RESULTS

We describe a surgical technique of minimally invasive mitral valve repair performed due to severe type IIIb FMR, which includes a modified subannular maneuver to realign both papillary muscles. Preliminary results of the first 10 patients who underwent this procedure at our institution are presented. There was no in-hospital mortality and follow-up echocardiography (mean ± SD echocardiographic follow-up = 10 ± 6 months) demonstrated stable functional results.

CONCLUSIONS

Our initial experience indicates that adding of this subannular maneuver to the standard annuloplasty and thereby fixing the distance between papillary muscles and mitral annular plane have a potential to improve results of surgical FMR treatment.

Mitral valve disease--morphology and mechanisms

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

Benefits of submitral procedures for ischemic mitral regurgitation

The surgical strategy for ischemic mitral regurgitation (MR) remains controversial. Ischemic MR is a secondary valve disease caused by left ventricular (LV) remodeling and subsequent papillary muscle displacement, usually without structural valve lesions. Reduction annuloplasty is the standard surgical procedure for this condition, though it cannot clearly provide a survival benefit for those with LV dysfunction and is associated with a high prevalence of late recurrence of MR. The valvular procedure alone could be insufficient to treat ischemic MR in terms of long-term survival and the prevention of recurrence because ischemic MR is primarily a ventricular disorder. Thus, recent studies have focused on alternative procedures that target the primary cause of ischemic MR, the papillary muscles and left ventricle. We believe that the appropriate selection of surgical procedures among valvular, subvalvular, and even ventricular ones, considering the severity of LV remodeling for each patient would be more beneficial. Here we review recent studies featuring various surgical approaches to ischemic MR, especially with submitral procedures.

Adjustable mitral annuloplasty for the surgical treatment of ischaemic mitral insufficiency

Presentation of the MiCardia enCorSQ annuloplasty device implantation technique for ischaemic mitral regurgitation including late-stage activation: exposure of mitral valve using video-assisted right lateral mini-thoracotomy, annuloplasty, tunnelling of permanently attached lead through the left atrial wall and subcutaneous implantation; and late activation: minor cut-down procedure for lead exposure, connection to proprietary energy source (MC-100 RF generator), echocardiography and fluoroscopy guidance, anterior-posterior diameter reduction of memory-shape alloy core annuloplasty device by raising the temperature a few degrees above body temperature.

Mitral valve replacement versus annuloplasty for treating severe functional mitral regurgitation

OBJECTIVES

To improve the clinical outcome of patients with severe functional mitral regurgitation (FMR) associated with ischemic cardiomyopathy (ICM), we compared the therapeutic efficacy of mitral annuloplasty (MAP) with that of mitral valve replacement (MVR).

METHODS

In a retrospective observation 63 consecutive patients underwent mitral valve surgery for severe ICM-FMR from November 1999 to March 2012. All patients had severe FMR (regurgitant volume >60 ml/beat) with Carpentier type I and type IIIb disease. Mean RV was 74.0 ± 35.0 ml/beat and coaptation depth was 12.7 ± 3.0 mm. Twenty-six patients (41.3 %) were treated by MVR with sparing of the subvalvular apparatus and 37 (58.7 %) by MAP.

RESULTS

Total in-hospital mortality was 6.3 %. Kaplan-Meier survival estimates at 1 and 5 years were 84.2 and 78.6 % in the MVR group and 82.6 and 71.6 % in the MAP group, with no significant difference between groups (p = 0.758). Freedom from major adverse cardiac and cerebrovascular events (MACCE) at 5 years was 66.9 % for patients treated by MVR and 64.1 % for those treated by MAP (p = 0.866). At the last follow-up visit, >grade II MR had recurred in 4 annuloplasty patients (10.8 %). In multivariate analysis, independent predictors of increased late death and MACCE were significantly associated with residual pulmonary hypertension (late death: odds ratio = 25.0, p = 0.0009; MACCE: odds ratio = 31.3, p = 0.0001).

CONCLUSIONS

Mitral valve replacement with sparing of the subvalvular apparatus is a safe and effective surgical alternative for patients with severe FMR.

Surgical management of ischemic mitral regurgitation: indications, procedures, and future prospects

Ischemic mitral regurgitation (IMR) is one of the most important risk factors affecting prognosis of patients who suffer from myocardial infarction. The mechanisms of IMR, the indications for surgical intervention, the operative procedures, and the limitations of surgical procedures are discussed in this review article.

Successful postoperative activation of an adjustable annuloplasty ring (MiCardia) in recurrent ischemic mitral valve regurgitation

We report the case of a 73-year-old patient with severe ischemic mitral regurgitation (MR). She subsequently underwent combined coronary artery revascularization and mitral valve annuloplasty using the adjustable enCorSQ device (MiCardia Corporation, Irvine, CA). Three months later she experienced recurrent symptomatic severe MR. Accessing the subcutaneous lead, activation and downsizing of the device within 45 seconds resulted in trace MR. The result was unchanged 1 month later.

Patient-specific finite element-based analysis of ventricular myofiber stress after Coapsys: importance of residual stress

BACKGROUND

We sought to determine regional myofiber stress after Coapsys device (Myocor, Inc, Maple Grove, MN) implantation using a finite element model of the left ventricle (LV). Chronic ischemic mitral regurgitation is caused by LV remodeling after posterolateral myocardial infarction. The Coapsys device consists of a single trans-LV chord placed below the mitral valve such that when tensioned it alters LV shape and decreases chronic ischemic mitral regurgitation.

METHODS

Finite element models of the LV were based on magnetic resonance images obtained before (preoperatively) and after (postoperatively) coronary artery bypass grafting with Coapsys implantation in a single patient. To determine the effect of Coapsys and LV before stress, virtual Coapsys was performed on the preoperative model. Diastolic and systolic material variables in the preoperative, postoperative, and virtual Coapsys models were adjusted so that model LV volume agreed with magnetic resonance imaging data. Chronic ischemic mitral regurgitation was abolished in the postoperative models. In each case, myofiber stress and pump function were calculated.

RESULTS

Both postoperative and virtual Coapsys models shifted end-systolic and end-diastolic pressure-volume relationships to the left. As a consequence and because chronic ischemic mitral regurgitation was reduced after Coapsys, pump function was unchanged. Coapsys decreased myofiber stress at end-diastole and end-systole in both the remote and infarct regions of the myocardium. However, knowledge of Coapsys and LV prestress was necessary for accurate calculation of LV myofiber stress, especially in the remote zone.

CONCLUSIONS

Coapsys decreases myofiber stress at end-diastole and end-systole. The improvement in myofiber stress may contribute to the long-term effect of Coapsys on LV remodeling.

Importance of anterior leaflet tethering in predicting recurrence of ischemic mitral regurgitation after restrictive annuloplasty

OBJECTIVE

We investigated the relationship between anterior mitral leaflet (AML) tethering and recurrent ischemic mitral regurgitation (MR) after restrictive annuloplasty. We also explored whether the effect of AML tethering was secondary to modifications in left ventricular size and geometry.

METHODS

The study population consisted of 435 consecutive patients with chronic ischemic MR who survived combined coronary artery bypass grafting and undersized mitral ring annuloplasty performed at 3 institutions (University Hospital, Maastricht, The Netherlands; Careggi Hospital, Florence, Italy; and Civic Hospital, Brescia, Italy) from 2001 to 2008. The median follow-up was 44.7 months (interquartile range 25.9-66.4). The patients were divided by the baseline measurements into quintiles of AML tethering angle α' as follows: group 1, normal/slight AML tethering; group 2, mild AML tethering; group 3, moderate AML tethering; group 4, moderate-to-severe AML tethering; and group 5, severe AML tethering.

RESULTS

Recurrence of MR was significantly greater in patients with moderate-to-severe (28.3%) and severe (39.4%) AML tethering (P < .001). A strong correlation was found between α' (r = 0.83, P < .001) and recurrent MR but a weak correlation with the posterior mitral angle β' (r = 0.12, P = .05). On logistic regression analysis corrected for other echocardiographic risk factors, moderate-severe AML tethering or worse (adjusted odds ratio, 3.6; 95% confidence interval, 3.0-4.1; P < .001) was a strong predictor of MR recurrence. Compared with patients with β' of 45 or greater, those with severe and moderate-severe AML tethering had more than 3.7 and 1.7 times greater odds of MR recurrence, respectively. No significant interactions were found between α' and the indexes of left ventricular function and geometry.

CONCLUSIONS

Preoperative moderate-severe AML tethering or worse was strongly associated with MR recurrence. Thus, assessment of leaflet tethering should be incorporated into clinical risk assessment and prediction models.

Impact of preoperative anterior leaflet tethering on the recurrence of ischemic mitral regurgitation and the lack of left ventricular reverse remodeling after restrictive annuloplasty

BACKGROUND

The aim of this multicenter study was to investigate the impact of the preoperative anterior mitral leaflet tethering angle, α', on the recurrence of mitral regurgitation (MR) and left ventricular (LV) reverse remodeling (LVRR) after undersized mitral ring annuloplasty.

METHODS

The study population consisted of 362 patients, who were divided into two groups by baseline α': group 1, α' < 39.5° (n = 196), and group 2, α' ≥ 39.5° (n = 166). End points were recurrent MR ≥ 2+; LVRR, defined as a reduction in end-systolic volume index > 15%; and LV geometric reverse remodeling, defined as a reduction in systolic sphericity index to a normal value of <0.72 in patients with altered baseline geometry.

RESULTS

MR occurred in 9.6% (n = 19) and 43.3% (n = 72) of the patients in groups 1 and 2, respectively (P < .001). LVRR (85.7% vs 22.2%) at follow-up was higher in group 1 (P < .001). On multivariate regression analysis, α' ≥ 39.5° was a strong predictor of MR recurrence, lack of LV reverse remodeling and lack of LV geometric reverse remodeling (all P values < .001). In contrast, the posterior mitral leaflet tethering angle, β', was not significant (all P values > .05). When we allowed for interactions between α' and other risk factors, this effect occurred also in low-risk subgroups, and it was equivalent or generally attenuated in higher risk patients. There were no significant interactions between α' and any of the covariates (all P values > .05).

CONCLUSIONS

Anterior mitral leaflet tethering is a powerful predictor of MR recurrence and lack of LVRR after undersized mitral ring annuloplasty. Evaluation of leaflet tethering should be incorporated into clinical risk assessment and prediction models.

Contribution of myocardium overlying the anterolateral papillary muscle to left ventricular deformation

Previous studies of transmural left ventricular (LV) strains suggested that the myocardium overlying the papillary muscle displays decreased deformation relative to the anterior LV free wall or significant regional heterogeneity. These comparisons, however, were made using different hearts. We sought to extend these studies by examining three equatorial LV regions in the same heart during the same heartbeat. Therefore, deformation was analyzed from transmural beadsets placed in the equatorial LV myocardium overlying the anterolateral papillary muscle (PAP), as well as adjacent equatorial LV regions located more anteriorly (ANT) and laterally (LAT). We found that the magnitudes of LAT normal longitudinal and radial strains, as well as major principal strains, were less than ANT, while those of PAP were intermediate. Subepicardial and midwall myofiber angles of LAT, PAP, and ANT were not significantly different, but PAP subendocardial myofiber angles were significantly higher (more longitudinal as opposed to circumferential orientation). Subepicardial and midwall myofiber strains of ANT, PAP, and LAT were not significantly different, but PAP subendocardial myofiber strains were less. Transmural gradients in circumferential and radial normal strains, and major principal strains, were observed in each region. The two main findings of this study were as follows: 1) PAP strains are largely consistent with adjacent LV equatorial free wall regions, and 2) there is a gradient of strains across the anterolateral equatorial left ventricle despite similarities in myofiber angles and strains. These findings point to graduated equatorial LV heterogeneity and suggest that regional differences in myofiber coupling may constitute the basis for such heterogeneity.

Impact of papillary muscle relocation as adjunct procedure to mitral ring annuloplasty in functional ischemic mitral regurgitation

BACKGROUND

The optimal surgical treatment in functional ischemic mitral regurgitation (FIMR) remains controversial. Recently, a posterior papillary muscle relocation (PMR) technique as adjunct procedure to ring annuloplasty has been proposed to prevent recurrent FIMR. In the present study, we used 3D cardiac MRI to assess the impact of relocating both papillary muscles as adjunct procedure to downsized ring annuloplasty on mitral leaflet coaptation geometry in FIMR pigs.

METHODS AND RESULTS

Eleven FIMR pigs were randomized to downsized ring annuloplasty (RA; n=6) or RA combined with PMR (RA+PMR, n=5). In the RA+PMR group, a 2-0 Gore-Tex suture was attached to each trigone, exteriorized through the corresponding papillary muscle, mounted on an epicardial pad, and tightened to relocate the myocardium adjacent to the anterior and posterior papillary muscles 5 and 15 mm, respectively. Using 3D MRI, the impact from these interventions on leaflet geometry was assessed. The distance from the posterior papillary muscle to the anterior trigone was reduced significantly more (median values) in the RA+PMR compared with RA animals at end-diastole (-7.9% versus 3.8%, P<0.01) and end-systole (-9.7% versus 2.5%, P=0.02). Accordingly, lateral tethering of the coaptation point (median values) was reduced significantly more in RA+PMR compared with RA animals (-42.8% versus -29.1%, P<0.01).

CONCLUSIONS

Adding papillary muscle relocation to downsized ring annuloplasty reduced lateral leaflet tethering in a porcine experimental model of FIMR. Therefore, this technique holds promise for reducing persistent and recurrent FIMR in patients.

Impact of subvalvular procedure for ischemic mitral regurgitation on leaflet configuration, mobility, and recurrence

BACKGROUND

Procedures on the subvalvular apparatus are an etiology-based treatment for ischemic mitral regurgitation (IMR).

METHODS AND RESULTS

Fifty-nine patients with IMR were divided into 3 groups: mitral annuloplasty (MAP) (M group, n=27), MAP+left ventricular reconstruction (LVR) (LV group, n=18), and MAP+LVR+subvalvular procedure (S group, n=14). Tenting height and area, angle between the annular line and the line connecting leaflet base to the bending- or tip-point of either the anterior or posterior leaflet, and leaflet mobility were measured echocardiographically preoperatively and at immediate- and mid-term postoperative follow-up. The angles at the bending-point of the anterior leaflet in mid-systole remained greater than those at its tip-point in the M and LV groups, but became significantly smaller postoperatively only in the S group (p<0.05). Postoperative leaflet mobility at the bending-point in the S group became significantly greater than in the other groups (p<0.01). The grade of MR, after significant reduction by the procedure, increased again in the M and LV groups, but remained almost unchanged in the S group.

CONCLUSION

Subvalvular procedures improved the configuration and mobility of the anterior leaflet, and can be expected to reduce the recurrence of IMR.