Mechanism of mitral leaflet excursion

Papillary muscle intervention vs mitral ring annuloplasty in ischemic mitral regurgitation

Background and Aims

The 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.

Methods

A 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.

Results

MR 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; I² = 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).

Conclusions

Using 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.

Mitral Annular Kinetics, Left Atrial, and Left Ventricular Diastolic Function Post Mitral Valve Repair in Degenerative Mitral Regurgitation

Objective

The relationship of mitral annular (MA) kinetics to left ventricular (LV) and left atrial (LA) function before and after mitral valve (MV) repair has not been well studied. Here we sought to provide comprehensive analysis that relates to MA motions, and LA and LV diastolic function post MV repair.

Methods

Three-dimensional analyses of mitral annular motion, LA function, and LV volumetric and diastolic strain rates were performed on 35 degenerative mitral regurgitation (MR) patients at baseline and 1-year post MV repair, and 51 normal controls, utilizing cardiac magnetic resonance imaging with tissue tagging.

Results

All had normal LV ejection fraction (EF) at baseline. LV and LA EFs decreased 1-year post-surgery vs. controls. LV early diastolic myocardial strain rates decreased post-surgery along with decreases in normalized early diastolic filling rate, E/A ratio, and early diastolic MA relaxation rates. Post-surgical LA late active kick remained higher in MR patients vs. control. LV and LA EFs were significantly associated with peak MA centroid to apex shortening. Furthermore, during LV systolic phase, peak LV ejection and LA filling rates were significantly correlated with peak MA centroid to apex shortening rate, respectively. While during LV diastolic phase, both peak early diastolic MA centroid to apex relaxation rate and LA ejection rate were positively significantly associated with LV peak early diastolic filling rate.

Conclusion

MA motion is significantly associated with LA and LV function. Mitral annular motion, left atrial function, and LV diastolic strain rates are still impaired 1 year post MV repair. Long-term effects of these impairments should be prospectively evaluated.

Mitral regurgitation in patients with heart failure. Interventional therapies

Mitral regurgitation (MR) is a common complication in heart failure patients, severely worsening their outcome. Because of the high perioperative risk, mitral valve surgery, which is the standard therapy for MR, is often not offered to these patients. Interventional therapies for mitral valve therapy might therefore constitute a novel therapeutic option particularly in this group. This article gives an overview of the available and evolving interventional strategies for mitral valve repair with a special emphasis on heart failure patients.

Ischemic mitral regurgitation: not only a bystander

Ischemic mitral regurgitation (MR) is a common complication of left ventricular (LV) dysfunction related to chronic coronary artery disease. This complex multifactorial disease involves global and regional LV remodeling, as well as dysfunction and distortion of the components of the mitral valve including the chordae, the annulus, and the leaflets. Its occurrence is associated with a poor prognosis. The suboptimal results obtained with the most commonly used surgical strategy, involving mitral valve annuloplasty with coronary bypass grafting, emphasize the need to develop alternative surgical techniques targeting the causal mechanisms of the disease. A comprehensive preoperative assessment of mitral valve configuration and LV geometry and function and an accurate quantification of MR severity at rest and during exercise may contribute to improve risk stratification and to tailor the surgical strategy according to the individual characteristics of the patient.

Optimal surgical management of severe ischemic mitral regurgitation: to repair or to replace?

BACKGROUND

Ischemic mitral regurgitation, a complication of myocardial infarction and coronary artery disease more generally, is associated with a high mortality rate and is estimated to affect 2.8 million Americans. With 1-year mortality rates as high as 40%, recent practice guidelines of professional societies recommend repair or replacement, but there remains a lack of conclusive evidence supporting either intervention. The choice between therapeutic options is characterized by the trade-off between reduced operative morbidity and mortality with repair versus a better long-term correction of mitral insufficiency with replacement. The long-term benefits of repair versus replacement remain unknown, which has led to significant variation in surgical practice.

METHODS AND RESULTS

This article describes the design of a prospective randomized clinical trial to evaluate the safety and effectiveness of mitral valve repair and replacement in patients with severe ischemic mitral regurgitation. This trial is being conducted as part of the Cardiothoracic Surgical Trials Network. This article addresses challenges in selecting a feasible primary end point, characterizing the target population (including the degree of mitral regurgitation) and analytical challenges in this high mortality disease.

CONCLUSIONS

The article concludes by discussing the importance of information on functional status, survival, neurocognition, quality of life, and cardiac physiology in therapeutic decision making.

Mitral cerclage annuloplasty, a novel transcatheter treatment for secondary mitral valve regurgitation: initial results in swine

OBJECTIVES

We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy.

BACKGROUND

Catheter-based annuloplasty for secondary mitral regurgitation exploits the proximity of the coronary sinus to the mitral annulus, but is limited by anatomic variants and coronary artery entrapment.

METHODS

The procedure, "cerclage annuloplasty," is guided by magnetic resonance imaging (MRI) roadmaps fused with live X-ray. A coronary sinus guidewire traverses a short segment of the basal septal myocardium to re-enter the right heart where it is exchanged for a suture. Tension is applied interactively during imaging and secured with a locking device.

RESULTS

We found 2 feasible suture pathways from the great cardiac vein across the interventricular septum to create cerclage. Right ventricular septal re-entry required shorter fluoroscopy times than right atrial re-entry, which entailed a longer intramyocardial traversal but did not cross the tricuspid valve. Graded tension progressively reduced septal-lateral annular diameter, but not end-systolic elastance or regional myocardial function. A simple arch-like device protected entrapped coronary arteries from compression even during supratherapeutic tension. Cerclage reduced mitral regurgitation fraction (from 22.8 +/- 12.7% to 7.2 +/- 4.4%, p = 0.04) by slice tracking velocity-encoded MRI. Flexible cerclage reduced annular size but preserved annular motion. Cerclage also displaced the posterior annulus toward the papillary muscles. Cerclage introduced reciprocal constraint to the left ventricular outflow tract and mitral annulus that enhanced leaflet coaptation. A sample of human coronary venograms and computed tomography angiograms suggested that most have suitable venous anatomy for cerclage.

CONCLUSIONS

Transcatheter mitral cerclage annuloplasty acutely reduces mitral regurgitation in porcine ischemic cardiomyopathy. Entrapped coronary arteries can be protected. MRI provided insight into the mechanism of cerclage action.

Efficacy of chordal cutting in alleviating ischemic mitral regurgitation: insights from 3-dimensional echocardiography

Background

Ischemic mitral regurgitation often complicates severe ischemic heart disease and adversely affects the prognosis in these patients. There is wide variation in the clinical spectrum of ischemic mitral regurgitation due to varying location and chronicity of ischemia and anomalies in annular and ventricular remodeling. As a result, there is lack of consensus in treating these patients. Treatment has to be individualized for each patient. Most of the available surgical options do not consistently correct this condition in all the patients. Chordal cutting is one of the newer surgical approaches in which cutting a limited number of critically positioned basal chordae have found success by relieving the leaflet tethering and thereby improving the coaptation of leaflets. Three-dimensional echocardiography is a potentially valuable tool in identifying the specific pattern of tethering and thus the suitability of this procedure in a given clinical scenario.

Case Presentation

A 66-year-old man with cardiomyopathy and ischemic mitral regurgitation presented to us with the features of congestive heart failure. The three-dimensional echocardiography revealed severe mitral regurgitation associated with the tethering of the lateral (P1) and medial (P3) scallops of the posterior leaflet of the mitral valve due to secondary chordal attachments. The ejection fraction was only 15% with severe global systolic and diastolic dysfunction. Mitral regurgitation was successfully corrected with mitral annuloplasty and resection of the secondary chordae tethering the medial and lateral scallops of the posterior leaflet of the mitral valve.

Conclusion

Cutting the second order chordae along with mitral annuloplasty could be a novel method to remedy Ischemic mitral regurgitation by relieving the tethering of the valve leaflets. The preoperative three-dimensional echocardiography should be considered in all patients with Ischemic mitral regurgitation to assess the complex three-dimensional interactions between the mitral valve apparatus and the left ventricle. This aids in timely surgical planning.

Increased distance between mitral valve coaptation point and mitral annular plane: significance and correlations in patients with heart failure

OBJECTIVE

To measure the distance between the mitral leaflet coaptation point and the mitral annulus (CPMA) and assess the relation of this index to structural and functional characteristics of the failing left ventricle.

DESIGN

Echocardiographic indices and CPMA were measured at baseline and again during dobutamine infusion and leg lifting. Left ventricular diastolic and systolic dimensions, left ventricular ejection fraction (LVEF) by Simpson's rule, mitral annulus dimension, and E point septal separation were correlated with CPMA.

SETTING

Tertiary referral centre.

PATIENTS

The total study population of 129 patients included 94 with LVEF < 35% and 35 with LVEF 35%-45%; 76 had coronary artery disease and 53 had dilated cardiomyopathy.

INTERVENTIONS

A dobutamine infusion was given in 18 patients and preload increase by leg lifting in 28.

MAIN OUTCOME MEASURES

Correlations between CPMA and contractility indices at baseline and during interventions.

RESULTS

CPMA was correlated with left ventricular diastolic dimension (r = 0.52), left ventricular systolic dimension (r = 0.53), LVEF (r = -0.44), fractional shortening (r = -0.42), E point septal separation (r = 0.48), and mitral annulus dimension (r = 0.44) (all p < 0.001). Dobutamine decreased CPMA from (mean (SD)) 12.04 (3.64) mm to 8.92 (2.56) mm and increased LVEF from 27 (6.2)% at baseline to 33.4 (6.9)% at 10 microg/kg/min (both p < 0.001). These changes were strongly related (r = 0.68, p < 0.007). After leg lifting, CPMA decreased from 13 (4) mm at baseline to 10 (3) mm (p < 0.001), and LVEF increased from 32 (11)% at baseline to 39 (11)% (p < 0.001). Fractional shortening and left ventricular diastolic dimension also increased (p < 0.001) and mitral annulus dimension and E point septal separation decreased (p < 0.002), but left ventricular systolic dimension did not change.

CONCLUSIONS

The mechanism displacing the mitral coaptation point towards the left ventricular apex is multifactorial. The correlations between CPMA difference (before versus after interventions) and ejection fraction difference (before versus after interventions) shows that this index depends mainly on left ventricular function.