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Efficacy of the Edge-to-Edge Repair in the Setting of a Dilated Ventricle: An In Vitro Study
Abstract
The edge-to-edge repair to correct mitral regurgitation (MR) has shown substandard results in cases of ischemic MR or dilated cardiomyopathy.
Ten porcine mitral valves were investigated in a left heart simulator (120 mm Hg, 5 L/min). Pathologic conditions of a dilated ventricle were simulated by using an annular model capable of three levels of dilation (normal, 56%, and 120%) and by displacing papillary muscles (PMs) 10 mm in the apical, lateral, and posterior directions. The edge-to-edge repair was performed; a central stitch was investigated for symmetric and asymmetric PM displacements, and a paracommissural stitch was investigated for asymmetric PM displacements. Left ventricular pressure and mitral flow rate were monitored, and regurgitation fraction was calculated from the mitral flow curve.
Under symmetric PM displacement, the repair reduced MR by 5.1% at dilation level one and by 9.1% at dilation level two. The repair decreased MR by 10.9% (dilation level two) after asymmetric displacement of the anterior-lateral PM, and by 5.4% (dilation level one) and 7.9% (dilation level two) after asymmetric displacement of the posterior-medial PM. The edge-to-edge repair reduced (p < 0.05) MR owing to annular dilation; however, it was unable to completely eliminate the MR. The repair did not significantly reduce MR caused by PM displacement, regardless of the displacement geometry. Stitch location did not affect repair efficacy.
The edge-to-edge repair is not an effective procedure in correcting MR associated with PM displacement, although it is able to partially reduce MR caused by annular dilation.
... Neilsen et al. measured the edgeto-edge suture tension in sheep, reporting highest tension in diastole when the leaflets retract away from coaptation, and the septal-lateral dimension of the mitral annulus is maximal. 138 In a dilated annulus, such diastolic tension could increase substantially, as demonstrated by an elegant study by Jimenez et al. 41,92 The impact of this tethering force on mitral leaflet stresses was investigated by numerous groups using finite element analysis, of which Votta et al. are pioneers. 172,182 Their model predicted that diastolic peak von mises stresses were compared to those computed at peak systole, indicating that the mitral leaflets were mechanically loaded through most of the cardiac cycle, which is highly non-physiological. ...
... Croft et al. in an elegant in vitro setup confirmed this hypothesis, observing that reduction in sMR was low after edge-to-edge repair in the setting of papillary muscle displacement. 41 The COAPT trial is an ongoing clinical trial investigating the safety and efficacy of the MitraClip system in patients with moderate to severe secondary mitral regurgitation who are high risk candidates for surgery, results from which will further elucidate the challenges with treating sMR with this device. ...
Mitral regurgitation is a common cardiac valve lesion, developing from primary lesions of the mitral valve or secondary to cardiomyopathies. Moderate or higher severity of mitral regurgitation imposes significant volume overload on the left ventricle, causing permanent structural and functional deterioration of the myocardium and heart failure. Timely correction of regurgitation is essential to preserve cardiac function, but surgical mitral valve repair is often delayed due to the risks of open heart surgery. Since correction of mitral regurgitation can provide symptomatic relief and halt progressive cardiac dysfunction, transcatheter mitral valve repair technologies are emerging as alternative therapies. In this approach, the mitral valve is repaired either with sutures or implants that are delivered to the native valve on catheters introduced into the cardiovascular system under image guidance, through small vascular or ventricular ports. Several transcatheter mitral valve technologies are in development, but limited clinical success has been achieved. In this review, we present a historical perspective of mitral valve repair, review the transcatheter technologies emerging from surgical concepts, the challenges they face in achieving successful clinical application, and the increasing rigor of safety and durability standards for new transcatheter valve technologies.
... MVs were explanted and mounted in the extensively studied Georgia Tech Left Heart Simulator, as previously described ( Figure 1A). [18][19][20][21] Using this closed-loop system, healthy human left heart hemodynamics were established for each valve (cardiac output 5.0 L/min, heart rate 70 beats/min with 70% diastole, peak transmitral pressure 120 mm Hg). Zero or trace MR was observed at this stage. ...
... 17 In the present study we explored the validity of 3D FOM in an ex vivo platform featuring whole explanted MVs (including the complete subvalvular apparatus) and a gold-standard flow probe. [18][19][20][21] The value of a diagnostic tool can be understood in terms of ease of use, accuracy, and repeatability. In evaluating ease of use, image acquisition and analysis should be considered separately. ...
Background: Accurate diagnosis of mitral regurgitation (MR) severity is central to proper treatment. While numerous approaches exist, an accurate, gold-standard clinical technique remains elusive. We previously reported on initial development and demonstration of the automated 3D-FOM algorithm, which exploits 3D-Color Doppler ultrasound imaging and builds on existing MR quantification techniques. The present study sought to extensively validate the three-dimensional Field Optimization Method (3D-FOM) in terms of accuracy, ease of use, and repeatability.
Methods: 3D-FOM was applied to 5 explanted ovine mitral valves in a left heart simulator, which were systematically perturbed to yield a total of 29 unique regurgitant geometries. 3D-FOM was compared to a gold-standard flow probe, as well as to the most clinically prevalent MR volume quantification technique, the two-dimensional Proximal Isovelocity Surface Area method (2D-PISA).
Results: Overall, 3D-FOM overestimated and 2D-PISA underestimated MR volume, but 3D-FOM error had smaller magnitude (5.2±9.9ml) than 2D-PISA error (-6.9±7.7ml). 2D-PISA remained superior in diagnosis for round orifices and especially mild MR, as predicted by ultrasound physics theory. For slit type orifices and severe MR, 3D-FOM showed significant improvement over 2D-PISA. 3D-FOM processing was technically simpler and significantly faster than 2D-PISA, while requiring fewer ultrasound acquisitions. 3D-FOM did not show significant inter-user variability, while 2D-PISA did.
Conclusions: 3D-FOM may provide increased clinical value compared to 2D-PISA, due to increased accuracy in the case of complex/severe regurgitant orifices as well as its greater repeatability and simpler workflow.
... The efficacy of a procedure is specified using an immense combination of factors, such as the durability of the repaired valve as well as the valve's function and hemodynamics under stress states. Thus, a myriad of studies are carried out to assess these parameters at follow-ups [59][60][61][62]. By approximating edge-to-edge repair (to repair ruptured/elongated chords) with chordal replacement, it was discovered that edge-to-edge repair and chordal replacement are sufficiently suited for the restoration of both the anterior and posterior leaflets [63]. ...
This paper provides a review of engineering applications and computational methods used to analyze the dynamics of heart valve closures in healthy and diseased states. Computational methods are a cost-effective tool that can be used to evaluate the flow parameters of heart valves. Valve repair and replacement have long-term stability and biocompatibility issues, highlighting the need for a more robust method for resolving valvular disease. For example, while fluid–structure interaction analyses are still scarcely utilized to study aortic valves, computational fluid dynamics is used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress, and oscillatory shear index in the thoracic aorta. It has been analyzed that computational flow dynamic analyses can be integrated with other methods to create a superior, more compatible method of understanding risk and compatibility.
... Note that the MV chamber acts as the left ventricle chamber, which is similar to previous studies. 4,10,14,15,21,24,32 More details on the setup are available in previous published work by our group. 15 A custom LabVIEW program controlled flow and pressure data acquisition as well as timing of compressed air and a vacuum that regulated the bladder pumps. ...
MitraClip transcatheter edge-to-edge repair is used to treat mitral regurgitation (MR). While MR is reduced, diastolic left ventricular flows are altered. An in vitro left heart simulator was used to assess a porcine mitral valve in the native, MR, and MR plus MitraClip cases. Velocity, vorticity, and Reynolds shear stress (RSS) were quantified by particle image velocimetry. Peak velocity increased from 1.20 m/s for native to 1.30 m/s with MR. With MitraClip, two divergent jets of 1.18 and 0.61 m/s emerged. Higher vorticity was observed with MR than native and lessened with MitraClip. MitraClip resulted in shear layer formation and downstream vortex formation. Native RSS decreased from 33 Pa in acceleration to 29 Pa at peak flow, then increased to 31 Pa with deceleration. MR RSS increased from 27 Pa in acceleration to 40 Pa at peak flow to 59 Pa during deceleration. MitraClip RSS increased from 79 Pa in acceleration to 162 Pa during peak flow, then decreased to 45 Pa during deceleration. After MitraClip, two divergent jets of reduced velocity emerged, accompanied by shear layers and recirculation. Chaotic flow developed, resulting in elevated RSS magnitude and coverage. Findings help understand consequences of MitraClip on left ventricular flow dynamics.
... Several in vitro models of SMR exist in literature [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], but none mimics the dynamic pathogenic interaction between the mitral valve and the left ventricle that is central to this lesion. We and others have reported isolated mitral Communicated by Associate Editor Adrian Chester oversaw the review of this article. ...
Development of transcatheter mitral valve interventions has ushered a significant need for large animal models of secondary mitral regurgitation. Though currently used heart failure models that chronically develop secondary mitral regurgitation are viable, the severity is lower than patients, the incubation time is long, and mortality is high. We sought to develop a swine model of acute secondary mitral regurgitation that uses image-guided placement of snares around the mitral chordae. Twenty-seven adult swine (n = 27) were assigned to secondary mitral regurgitation induced by valve tethering with image-guided chordal encircling snares (group 1, n = 7, tether MR (tMR)); secondary mitral regurgitation by percutaneous posterolateral myocardial infarction causing ventricular dysfunction and regurgitation (group 2, n = 6, functional MR (fMR)); and control animals (group 3, n = 14). Regurgitant fraction in tMR was 42.1 ± 14.2%, in fMR was 22 ± 9.6%, and in controls was 5.3 ± 3.8%. Mitral tenting height was 9.6 ± 1.3 mm in tMR, 10.1 ± 1.5 mm in fMR, and 5.8 ± 1.2 mm in controls. Chordal encircling tethers reproducibly induce clinically relevant levels of secondary mitral regurgitation, providing a new animal model for use in translational research.
Graphical abstract
... These altered dimensions were based on a variety of clinical findings comparing patients with FMR to controls 7,20,39 and values used to create in vitro FMR. 11,25,37 The harvested valves were then placed in the neutral position and papillary muscles were displaced 5 mm apically, away from the valve annulus, and 5 mm laterally, creating the high-tension tethering of FMR. These displacements have been previously shown to elevate tension on anterior strut, posterior basal, and commissural chordae, thereby increasing leaflet tenting and regurgitation. ...
Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5 mm displacement of papillary muscles towards the annulus), and FMR (5 mm apical, 5 mm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics.
... Sheep models showed no significant difference in terms of degree of regurgitation between repaired and non-repaired valves during acute IMR 31 . In an elegant in vitro study, Croft and colleagues simulated IMR with and without annular dilation, before and after edge-to-edge repair, on porcine isolated valves mounted in a pulsatile mock loop comprising a left-heart simulator (GeorgiaTech Left Heart Simulator) and instrumented with pressure and flow transducers 35 . The experimental set-up allowed for tuning PMs position in the 3D space by means of ad hoc actuators and annular dimensions by means of a draw string mechanism. ...
Mitral regurgitation is the most prevalent heart valve disease in the western population. When severe, it requires surgical treatment, repair being the preferred option. The edge-to-edge repair technique treats mitral regurgitation by suturing the leaflets together and creating a double-orifice valve. Due to its relative simplicity and versatility, it has become progressively more widespread. Recently, its percutaneous version has become feasible, and has raised interest thanks to the positive results of the Mitraclip® device. Edge-to-edge features and evolution have stimulated debate and multidisciplinary research by both clinicians and engineers. After providing an overview of representative studies in the field, here we propose a novel computational approach to the most recent percutaneous evolution of the edge-to-edge technique. Image-based structural finite element models of three mitral valves affected by posterior prolapse were derived from cine-cardiac magnetic resonance imaging. The models accounted for the patient-specific 3D geometry of the valve, including leaflet compound curvature pattern, patient-specific motion of annulus and papillary muscles, and hyperelastic and anisotropic mechanical properties of tissues. The biomechanics of the three valves throughout the entire cardiac cycle was simulated before and after Mitraclip® implantation, assessing the biomechanical impact of the procedure. For all three simulated MVs, Mitraclip® implantation significantly improved systolic leaflets coaptation, without inducing major alterations in systolic peak stresses. Diastolic orifice area was decreased, by up to 58.9%, and leaflets diastolic stresses became comparable, although lower, to systolic ones. Despite established knowledge on the edge-to-edge surgical repair, latest technological advances make its percutanoues implementation a challenging field of research. The modeling approach herein proposed may be expanded to analyze clinical scenarios that are currently critical for Mitraclip® implantation, helping the search for possible solutions.
... A left heart flow loop was developed in order to reproduce physiologic pressure and flow waveforms (Fig. 1A). Others have used similar flow simulators in an effort to study MV disease states and the effects of various repair strategies on MV mechanics (Croft et al., 2007;Padala et al., 2009). MVs were obtained from healthy pigs from a local abattoir (Hampton Meats, Hopkinsville, KY), and the entire MV apparatus was excised and kept intact. ...
... We believe these in vivo data will supplement the elegant in vitro experiments and computational models of Dr Yoganathan's Georgia Tech Group. 3 As to the study at hand, we have amended our original article with revised versions of Figures 2 and 3 to include standard deviation bars so as to address the potential inconsistencies pointed out by Dasi and colleagues. Neither mitral annular area nor stitch tension decreased during diastole as shown in the revised Figure 2 and confirmed by frame-to-frame statistical analysis throughout diastole. ...
We welcome the salient comments by Dasi and colleagues pertaining to our work on the effect of chronotropy and inotropy on leaflet stitch tension in the Alfieri mitral valve repair.1 The authors make sound scientific arguments, and we agree that knowing instantaneous flow rate would enhance our understanding of the true determinants of stitch …
... These results indicate that combined annuloplasty may be necessary in many patients to increase durability of the edge-to-edge repair by reducing annular dilation. A further study by Croft et al. demonstrated that edge-to-edge repair alone can reduce, but not completely eliminate, MR due to annular dilation [37]. It was also found that edge-to-edge repair alone is ineffective at reducing MR due to papillary muscle displacement, providing evidence that in many cases, edge-to-edge repair may be secondary to annuloplasty in the reduction of MR. ...
There has been a great deal of interest in percutaneous mitral valve repair techniques in recent years, with several devices undergoing animal testing and clinical trials. Percutaneous annuloplasty and leaflet repair devices are currently in development, and while safety rates have generally been equal or superior to conventional surgical techniques, efficacy has been suboptimal. Most current percutaneous mitral valve repair devices can only reduce regurgitant volumes by approximately 20-40%, but these reductions may be enough to treat high-risk patients, including the elderly and those with comorbidities, who are otherwise ineligible for surgery. An analysis of how these devices alter the geometry and mechanics of the mitral valve apparatus can provide insight into long-term efficacy and durability and may lead to improvements in the reduction of mitral regurgitation. In the future, multiple percutaneous techniques may be utilized in combination to increase overall efficacy. In this article, we report on percutaneous mitral valve repair techniques with published clinical or animal data.
Understanding the biomechanics of mitral valves (MVs) has significance for both surgical treatment and regenerative medicine. The biomechanics and mechanobiology of MVs is influenced by their complex anatomy, together with their extracellular matrix (ECM) composition and organization. Valve cells are mechanoresponsive, both to the hemodynamically active environment which the valve tissue is constantly exposed, as well as the altered hemodynamics of valve disease. This chapter will discuss the various tissue and cell level culture techniques and biomechanical approaches to date for examining MV biomechanics and mechanobiology, as well as directions for future studies.
The edge-to-edge repair (ETER) technique has been used as a stand-alone procedure, or as a secondary procedure with ring annuloplasty for degenerative, functional mitral regurgitation, or for mitral regurgitation of other kinds of valvular etiologies. The percutaneous MitraClip technique based on ETER has been used in patients who are inoperable or at high surgical risk. However, adverse events such as residual mitral regurgitation, and clip detachment or fracture indicate that the mechanics underlying these procedures is not well understood. Therefore, current studies on mitral valve functionality and mechanics related to the ETER and MitraClip procedures are reviewed to improve the efficacy and safety of both procedures. Extensive in vivo, in vitro, and in silico studies related to ETER and MitraClip procedures along with MitraClip clinical trial results are presented and discussed herein. The ETER suture force and the mitral valve tissue mechanics and hemodynamics of each procedure are discussed. A quantitative understanding of the interplay of mitral valve components and as to biological response to the procedures remains challenging. Based on mitral valve mechanics, ETER or MitraClip therapy can be optimized to enhance repair efficacy and durability.
The mitral valve (MV), located between the left atrium and left ventricle of the heart, is responsible for preventing retrograde blood flow by closing during systole. There are two MV leaflets, anterior and posterior. The anterior is the larger of the two and semicircular; the posterior leaflet is more rectangular and can be subdivided into three scallops, the middle scallop being the largest in most human hearts. The two leaflets are anchored to the wall of the left ventricle by the chordae tendinae. The MV annulus forms a complete fibrous ring anchored along the anterior leaflet (1).
Computational models for the heart's mitral valve (MV) exhibit several uncertainties that may be reduced by further developing these models using ground-truth data-sets. This study generated a ground-truth data-set by quantifying the effects of isolated mitral annular flattening, symmetric annular dilatation, symmetric papillary muscle (PM) displacement and asymmetric PM displacement on leaflet coaptation, mitral regurgitation (MR) and anterior leaflet strain. MVs were mounted in an in vitro left heart simulator and tested under pulsatile haemodynamics. Mitral leaflet coaptation length, coaptation depth, tenting area, MR volume, MR jet direction and anterior leaflet strain in the radial and circumferential directions were successfully quantified at increasing levels of geometric distortion. From these data, increase in the levels of isolated PM displacement resulted in the greatest mean change in coaptation depth (70% increase), tenting area (150% increase) and radial leaflet strain (37% increase) while annular dilatation resulted in the largest mean change in coaptation length (50% decrease) and regurgitation volume (134% increase). Regurgitant jets were centrally located for symmetric annular dilatation and symmetric PM displacement. Asymmetric PM displacement resulted in asymmetrically directed jets. Peak changes in anterior leaflet strain in the circumferential direction were smaller and exhibited non-significant differences across the tested conditions. When used together, this ground-truth data-set may be used to parametrically evaluate and develop modelling assumptions for both the MV leaflets and subvalvular apparatus. This novel data may improve MV computational models and provide a platform for the development of future surgical planning tools.
AimsPercutaneous treatment of mitral regurgitation (MR) has been shown to reduce MR severity and improve functional outcomes. Surgical treatment of MR usually includes mitral annulus reduction. The influence of the MitraClip ® on annulus geometry is not clear. We wanted to investigate whether the procedure itself reduces annulus diameter and if there may be differences between secondary or functional (SMR) and primary (PMR) MR.Methods and resultsWe retrospectively assessed 3D echocardiography (3D-TEE) data of 55 patients acquired during the procedure shortly before and after clip placement for changes in annulus diameter and area. Measurements were done with QLAB software. Patients were categorized as having either SMR (n = 41) or PMR (n = 14). In SMR, we were able to demonstrate a significant reduction in annulus area (meanΔ 1.30 ± 1.44 cm2; P < 0.001), anterior-posterior (AP)-diameter (meanΔ 0.28 ± 0.32 cm; P < 0.001), tenting area (meanΔ 0.39 ± 0.49 cm2; P < 0.001). No significant change could be found for latero-medial (LM)-diameter. In contrast, we could not demonstrate significant changes in any of the parameters described above in patients with PMR.Conclusion
Percutaneous treatment with the MitraClip® device can produce immediate reductions in mitral annulus size in SMR, probably supporting procedural success. It also reduces tenting, which may have prognostic implications. In contrast, these effects on mitral geometry cannot be demonstrated in PMR. Knowledge of this difference between SMR and PMR may be important to improve procedural strategies. © 2013 Published on behalf of the European Society of Cardiology. All rights reserved.
Myxomatous mitral valve disease is a form of mitral valve prolapse, which is characterized by a disorganized collagen matrix
with excessive glycosaminoglycan content. Due to loss of mechanical competence and increased surface area of the mitral valve
leaflets, this disease leads to regurgitation and cardiac dysfunction. There is a strong clinical need for percutaneous treatment
of patients with myxomatous mitral valve disease and regurgitation as an alternative to open-chest surgery. We have previously
examined the efficacy of radiofrequency ablation of the mitral valve leaflets as a strategy to reduce prolapse and regurgitation
in a canine model. Prior to testing this strategy further in a large animal model, we sought to determine the ‘therapeutic
window’ that should be targeted in vitro. Here, we quantified both the geometrical and biomechanical compliance changes of porcine mitral valve anterior leaflets
before and after radiofrequency ablation at various powers (Watts) for 15s. Following ablation, there was significant shortening
in the circumferential direction after 15 and 25W, which led to significant decreases in surface area at these powers. Under
an equibiaxial membrane tension of 90N/m, which approximates systolic loading of 120mmHg, axial strain in the radial direction
was predominantly affected following ablation with significant decreases following 10, 15, and 25W. Circumferential strain
was not different following any ablation power, except 25W when it was significantly increased. Areal strain at 90N/m was
significantly decreased following 10 and 15W ablations, but was increased following 25W. These data indicate that radiofrequency
ablation decreases mitral valve leaflet surface area and compliance, but only achieving both within a narrow therapeutic window.
To maximize both of these effects, 15W appears to be the target power. While 25W leads to ~25% reduction in tissue area,
it results in increased compliance. We speculate that at this power, collagen fibers may be failing due to rupture, either
directly from ablation or once they are mechanically loaded.
KeywordsMitral valve-Catheter ablation-Mechanics
We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy.
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.
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.
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.
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.
The mitral valve edge-to-edge repair (ETER) procedure inevitably alters mitral valve leaflet mechanics. The study aim was to quantify the effects of papillary muscle (PM) position on stretches in the central area of the anterior leaflet after mitral valve ETER.
Sixteen markers of a 4x4 array were attached onto the central area of the mitral valve anterior leaflet. The free edges of the mitral valve leaflets were sutured together with a single stitch to mimic the ETER. The mitral valve was then mounted in an in-vitro flow loop that was capable of simulating physiological loading conditions. The PM of the mitral valve was set in slack, normal, and taut positions. Displacements of the markers were obtained from the images of the markers, in order to calculate the stretches and stretch rates.
The major principal stretch during systole was significantly greater than that during diastole in the three PM positions. The major principal (radial) stretch was significantly greater in the taut PM position than in the normal and slack PM positions during diastole. However, there was no significant difference in the minor principal (circumferential) stretch during diastole in the three PM positions. The loading and unloading stretch rates were not affected by the PM position, except for the major principal stretch rate during loading.
With regards to the central region of the mitral valve anterior leaflet, the radial stretch during diastole was significantly less than that during systole. Therefore, the load on the anterior leaflet during systole, rather than that during diastole, should be considered when evaluating ETER durability, especially in the taut PM position. The circumferential stretch during diastole was not influenced by the PM positions.
Mitral insufficiency, a common and morbid pathology, has been related to topological changes in the left ventricle. These changes may affect mitral leaflet coaptation by displacing the tips of the papillary muscles (PMs), subsequently changing the tension distribution on the chordae tendineae. Therefore, further understanding of the effects of PM displacement on chordal force distribution is required.
Six human and five porcine mitral valves were studied in a physiological left heart simulator. Cardiac output and transmitral pressure were recorded online and maintained within physiological ranges. Force transducers were placed on six chordae tendineae to measure chordal force distribution. Tension on individual chordae tendineae was recorded online during the cardiac cycle. The experiment was conducted for eight different PM positions, which were constructed from 5-mm vectorial displacements from the normal PM position.
The anterior strut chord showed significant (p <0.05) variations in peak systolic tension (PST) for those positions associated with apical motion of the PMs. The posterior intermediate chord also showed significant variations in PST for positions associated with apical displacement of the PMs, whereas posterior displacement of the PMs resulted in a reduction in tension. In contrast, both the anterior marginal and posterior marginal chords showed a relatively uniform PST for the eight different PM positions. The posterior basal and commissural chords were the most sensitive to tension variations due to PM displacement. These chords showed relatively large and significant (p <0.05) variations in PST for most of the different PM displacements.
The effects of PM relocation on chordal tension depended on chordal type. Chords which insert closer to the annulus were more sensitive to PM displacement, whereas those further from the annulus, the marginal chords, were the least sensitive to PM displacement.
Objectives:
The aim of this study was to examine the temporal association between the onset of functional mitral regurgitation and the development of changes in left ventricular shape, chamber enlargement, mitral anulus dilation and regional wall motion abnormalities during the course of evolving heart failure.
Background:
Despite extensive characterization, the exact etiology of functional mitral regurgitation in patients with chronic heart failure remains unknown.
Methods:
Heart failure was produced in seven dogs by multiple sequential intracoronary microembolizations. Serial changes in left ventricular chamber volume and shape were evaluated from ventriculograms. Changes in mitral anulus diameter and ventricular regional wall motion abnormalities were evaluated echocardiographically. The presence and severity of mitral regurgitation were determined with Doppler color flow mapping. Measurements were obtained at baseline and then biweekly until mitral regurgitation was first observed.
Results:
No dog had mitral regurgitation at baseline but all developed mild to moderate regurgitation 12 +/- 1 weeks after the first embolization. The onset of mitral regurgitation was not associated with an increase in left ventricular end-diastolic volume relative to baseline (58 +/- 3 vs. 62 +/- 3 ml), mitral anulus diameter (2.4 +/- 0.1 vs. 2.4 +/- 0.1 cm) or wall motion abnormalities of left ventricular wall segments overlying the papillary muscles. In contrast, the onset of mitral regurgitation was accompanied by significant changes in global left ventricular shape evidenced by increased end-systolic chamber sphericity index (0.22 +/- 0.02 vs. 0.30 +/- 0.01) (p < 0.01) and decreased end-systolic major axis/minor axis ratio (1.71 +/- 0.05 vs. 1.43 +/- 0.04) (p < 0.001).
Conclusions:
These data indicate that transformation of left ventricular shape (increased chamber sphericity) is the most likely substrate for the development of functional mitral regurgitation.
Recent advances in three-dimensional (3D) echocardiography allow us to address uniquely 3D scientific questions, such as the mechanism of functional mitral regurgitation (MR) in patients with left ventricular (LV) dysfunction and its relation to the 3D geometry of mitral leaflet attachments. Competing hypotheses include global LV dysfunction with inadequate leaflet closing force versus geometric distortion of the mitral apparatus by LV dilatation, which increases leaflet tethering and restricts closure. Because geometric changes generally accompany dysfunction, these possibilities have been difficult to separate.
We created a model of global LV dysfunction by esmolol and phenylephrine infusion in six dogs. initially with LV expansion limited by increasing pericardial restraint and then with the pericardium opened. The mid-systolic 3D relations of the papillary muscle (PM) tips and mitral valve were reconstructed. Despite severe LV dysfunction (ejection fraction, 18+/-6%), only trace MR developed when pericardial restraint limited LV dilatation; with the pericardium opened, moderate MR accompanied LV dilatation (end-systolic volume, 44+/-5 mL versus 12+/-5 mL control, P<.001). Mitral regurgitant volume and orifice area did not correlate with LV ejection fraction and dP/dt (global function) but did correlate with changes in the tethering distance from the PMs to the anterior annulus derived from the 3D reconstructions, especially PM shifts in the posterior and mediolateral directions, as well as with annular area (P<.0005). By multiple regression, only changes in the PM-to-annulus distance independently predicted MR volume and orifice area (R2=.82 to .85, P=2x10(-7) to 6x10(-8)).
LV dysfunction without dilatation fails to produce important MR. Functional MR relates strongly to changes in the 3D geometry of the mitral valve attachments at the PM and annular levels, with practical implications for approaches that would restore a more favorable configuration.
Functional mitral regurgitation in patients with ischemic or dilated ventricles has been related to competing factors: altered tension on the leaflets due to displacement of their papillary muscle and annular attachments, which restricts leaflet closure, versus global ventricular dysfunction with reduced transmitral pressure to close the leaflets. In vivo, however, geometric changes accompany dysfunction, making it difficult to study these factors independently. Functional mitral regurgitation also paradoxically decreases in midsystole, despite peak transmitral driving pressure, suggesting a change in the force balance acting to create a regurgitant orifice, with rising transmitral pressure counteracting forces that restrict leaflet closure. In vivo, this mechanism cannot be tested independently of annular contraction that could also reduce midsystolic regurgitation.
An in vitro model was developed that allows independent variation of papillary muscle position, annular size, and transmitral pressure, with direct regurgitant flow rate measurement, to test the hypothesis that functional mitral regurgitation reflects an altered balance of forces acting on the leaflets. Hemodynamic and echocardiographic measurements of excised porcine valves were made under physiological pressures and flows. Apical and posterolateral papillary muscle displacement caused decreased leaflet mobility and apical leaflet tethering or tenting with regurgitation, as seen clinically. It reproduced the clinically observed midsystolic decrease in regurgitant flow and orifice area as transmitral pressure increased. Tethering delayed valve closure, increased the early systolic regurgitant volume before complete coaptation, and decreased the duration of coaptation. Annular dilatation increased regurgitation for any papillary muscle position, creating clinically important regurgitation; conversely, increased transmitral pressure decreased regurgitant orifice area for any geometric configuration.
The clinically observed tented-leaflet configuration and dynamic regurgitant orifice area variation can be reproduced in vitro by altering the three-dimensional relationship of the annular and papillary muscle attachments of the valve so as to increase leaflet tension. Increased transmitral pressure acting to close the leaflets decreases the regurgitant orifice area. These results are consistent with a mechanism in which an altered balance of tethering versus coapting forces acting on the leaflets creates the regurgitant orifice.
In the absence of papillary muscle rupture, the precise deformations that cause acute postinfarction mitral valve regurgitation are not understood and impair reparative efforts.
In 6 Dorsett hybrid sheep, sonomicrometry transducers were placed around the mitral annulus (n = 6) and at the tips and bases of both papillary muscles (n = 4). Later, specific circumflex coronary arteries were occluded to infarct approximately 32% of the posterior left ventricle and produce acute 2 to 3+ mitral regurgitation. Before and after infarction, distance measurements between sonomicrometry transducers produced three-dimensional coordinates of each transducer every 5 ms.
After infarction, the annulus dilated asymmetrically orthogonal to the line of leaflet coaptation, but the annular area increased only 9.2% +/- 6.3% (p = 0.02). At end-systole, posterior papillary muscle length increased 2.3 +/- 0.9 mm (p = 0.005); the posterior papillary muscle tip moved closer to the annular plane and centroid, and the anterior papillary muscle tip moved away.
Small deformations in mitral valvular spatial geometry after large posterior infarctions are sufficient to produce moderate to severe mitral regurgitation. The most important changes are asymmetric annular dilatation, prolapse of leaflet tissue tethered by the posterior papillary muscle, and restriction of leaflet tissue attached to the anterior papillary muscle.
Acute posterior myocardial infarction that produces immediate mitral regurgitation alters the mitral annulus and its spatial relationship with both papillary muscles. The precise deformations that cause valve insufficiency are not understood and impair efforts to repair the valve.
In six Dorsett hybrid sheep, sonomicrometry transducers were placed around the mitral annulus (6) and at the tips and bases of both papillary muscles (4). Two weeks later, three branches of the circumflex coronary artery were occluded to infarct approximately 32% of the posterior left ventricle. This infarction produced acute 2 to 3+ mitral regurgitation in all animals, as determined by color flow Doppler velocity mapping. Before and after infarction, distance measurements between sonomicrometry transducers were used to produce the three-dimensional coordinates of each transducer every 5 ms. After infarction, the area of the annulus increased only 9.2+/-6.3% at end systole (ES). In addition, the normal shortening of the posterior papillary muscle was obliterated to allow its tip to move 1.4+/-0.6 mm closer to the centroid of the annulus at ES. After infarction, the anterior papillary muscle continued to shorten normally, but at ES, its tip and base were 0.9+/-0.7 mm and 1.3+/-0.7 mm farther from the centroid, respectively.
These deformations tend to produce a relative prolapse of leaflet tissue attached to the posterior papillary muscle and restriction of leaflet tissue attached to the anterior papillary muscle. This papillary muscle discoordination with minimal annular dilatation distorts leaflet coaptation sufficiently to produce severe mitral regurgitation.
Repair of mitral regurgitation (MR) is more demanding in case of prolapse of the anterior leaflet, posterior leaflet with calcified annulus, or prolapse of both leaflets. We evaluated a repair which consists of anchoring the free edge of the prolapsing leaflet to the corresponding free edge of the facing leaflet: the 'edge-to-edge' (E-to-E) technique. The correction results in a double orifice valve when the prolapse is in the middle portion of the leaflet and in a smaller valve orifice when the prolapse is close to a commissure.
Out of 432 patients with MR submitted to valve repair between January 1991 and September 1997, 121 (mean age 56 +/- 15.8 years) underwent E-to-E correction. The most prevalent etiology was degenerative disease (82 patients, 68%). The mechanism of MR was anterior leaflet prolapse (61 patients), posterior leaflet prolapse (24 patients), prolapse of both leaflets (28 patients) and other complex mechanisms (8 patients). In 72 patients, a double orifice was created, the paracommissural repair was done in 49 patients.
Hospital mortality was 1.6%. Overall survival was 92 +/- 3.1% at 6 years with 95 +/- 4.8% freedom from reoperation. Mortality was unrelated to the type of repair. Mitral stenosis was never observed after the correction. At the follow-up (mean 2.2 +/- 1.5 years), all patients but 15 are class I or II. Symptoms at the follow-up are not related to residual MR.
Midterm results of this alternative repair technique are promising, considering the high prevalence of complex anatomical lesions. The technique is simple, easily reproducible and rapidly feasible also when mitral exposure is suboptimal.
Mitral annulus dilatation has been identified as an important factor in functional mitral regurgitation (FMR). However, the pathophysiologic interaction of annular dilatation and papillary muscle (PM) displacement in FMR, which occurs clinically in left ventricular (LV) dilatation, is still not well understood. It is difficult to separate these competing factors in vivo, leading to confusion in identifying the real role of the annular dilatation in FMR and its interaction with PM displacement.
To better understand the competing factors, an in vitro model was developed with a D-shaped adjustable mitral annulus that could be changed from 5.5 cm2 to 13.0 cm2 during experiments, independent of varying PM positions. Six excised normal porcine mitral valves were mounted in a left ventricular model with the adjustable annulus device and tested in a physiologic pulsatile flow system under normal cardiac output and left ventricular pressure (5.0 l/min, 120 mmHg). Papillary muscles were placed in normal and then displaced to an apical posterolateral position, to simulate pathological conditions seen clinically. Regurgitation was measured directly by a flow probe and the mitral valve geometry and leaflet coaptation were recorded by video camera through the model's atrium window. In addition, 2D echocardiography was used to evaluate leaflet coaptation and color Doppler flow mapping to detect the regurgitant flow field.
The results showed that in normal PM position, the mitral regurgitant was consistently at low level until the annulus was enlarged to 1.75 times the normal size, at which time it increased sharply. Papillary muscle apical posterolateral displacement, which simulates a dilated LV, caused regurgitation to occur earlier (1.5 times the normal annulus size), and had an increased regurgitant volume (p < 0.05). The leaflet gaps were first observed at the commissural areas of the valves, consistent with the location of regurgitant jets detected by color Doppler flow mapping. Asymmetric PM displacement created more regurgitation than both the symmetric PM tethering (p = 0.063) and normal PM position (p < 0.01). The regurgitant jets were observed at the same commissural side as the PM displacement, even without significant enlargement of the annulus.
This in vitro study provides insight into the interaction between annular dilatation and PM displacement on FMR. The resulting effects and their overall similarity to clinical observation could help further understand the mechanism of FMR and provide additional information to improve future therapeutic strategies.
The study aim was to test the hypothesis that asymmetric alignment (misalignment) of the papillary muscles is sufficient to cause incomplete mitral leaflet coaptation and functional mitral regurgitation (MR).
Different spatial relationships between the papillary muscles and the mitral annulus were investigated in isolated porcine mitral valves in vitro to assess the impact on mitral valve competence. The systolic occlusional leaflet area (OLA) needed to cover the mitral orifice and the anterolateral (ACOM) and posteromedial (PCOM) commissural portion (OLA(ACOM), OLA(PCOM)) were assessed by 2D echocardiography to quantitate incomplete mitral leaflet coaptation. The regurgitant fraction (RF) and MR jet location were assessed by a flow meter and color Doppler ultrasound.
Posterolateral dislocation of the posteromedial papillary muscle impaired mitral leaflet coaptation at the corresponding half-portion of the mitral orifice (OLA(PCOM): 351-397 mm2 versus 296 mm2 (normal); p < 0.001) and modified the contralateral part (OLA(ACOM): 354-387 mm2 versus 304 mm2 (normal); p <0.001). The mitral leaflet coaptation line moved in apical and posterior directions, creating a commissural MR orifice at the PCOM side. At the ACOM side, anterior leaflet prolapse and restricted posterior leaflet mobility created an additional commissural regurgitant jet (RF = 0.11-0.13). Symmetrical papillary muscle misalignment restricted mitral leaflet mobility on both sides of the orifice in a synergistic manner (OLA(PCOM): 416-459 mm2 and OLA(ACOM): 427-489 mm2; both p <0.001 versus normal). The central MR jet orifice, which extended towards both commissures, caused more significant MR (RF = 0.15-0.26).
Papillary muscle misalignment caused mitral regurgitant jet ambiguity with an anterior MR jet location following posteromedial papillary muscle displacement. These findings may improve understanding of the relation between myocardial lesion and mitral regurgitant jet location and thereby facilitate rational strategies for valvular interventions.
To compare mitral annular shape and motion throughout the cardiac cycle in patients with normal hearts versus those with functional mitral regurgitation (FMR).
The causes of mitral regurgitation without valvular disease are unclear, but the condition is associated with changes in annular shape and dynamics. Three-dimensional (3D) imaging provides a more comprehensive view of annular structure and allows accurate reconstructions at high spatial and temporal resolution.
Nine normal subjects and 8 patients with FMR undergoing surgery underwent rotationally scanned transesophageal echocardiography. At every video frame of 1 sinus beat, the mitral annulus was manually traced and reconstructed in 3D by Fourier series. Annular projected area, nonplanarity, eccentricity, perimeter length, and interpeak and intervalley spans were determined at 10 time points in systole and 10 points in diastole.
The mitral annulus in patients with FMR had a larger area, perimeter, and interpeak span than in normal subjects (P <.001 for all). At mid-systole in normal annuli, area and perimeter reach a minimum, nonplanarity is greatest, and projected shape is least circular. These cyclic variations were not significant in patients with FMR. Annular area change closely paralleled perimeter change in all patients (mean r = 0.96 +/- 0.07).
FMR is associated with annular dilation and reduced cyclic variation in annular shape and area. Normal mitral valve function may depend on normal annular 3D shape and dimensions as well as annular plasticity. These observations may have implications for design and selection of mitral annular prostheses.
Mitral regurgitation in cases of prolapse of the anterior leaflet, posterior leaflet with calcified annulus, or prolapse of both leaflets is thought to be difficult to repair. The Alfieri repair has been developed to address these conditions.
Seven patients (four men and three women, mean age 71 +/- 9 years) underwent the Alfieri repair for mitral regurgitation at Austin and Repatriation Medical Centre between January 1999 and December 1999. The mechanism of mitral regurgitation was prolapse of the posterior leaflet with calcified annulus in one patient, prolapse of the anterior leaflet in two, and prolapse of both leaflets in four. Mitral regurgitation before operation was severe in all patients. The Cosgrove ring was used in all patients. Four patients underwent combined operation, coronary artery bypass surgery in three and tricuspid annuloplasty in one.
There was no hospital death. Two patients had postoperative complications, transient ischemic attack in one patient and rapid atrial fibrillation in one. The mean hospital stay was 11.3 +/- 8.7 days. Mitral regurgitation after operation was mild in five patients and trivial in two. Mean pressure gradient of the transmitral valve was 4.0 +/- 1.4 mmHg.
The Alfieri mitral valve repair is a simple and satisfactory technique to repair mitral regurgitation in selected patients. Long-term follow-up is required to evaluate the durability of this technique.
The aim of this study is to report our results with the central double-orifice technique used for the treatment of complex mitral valve lesions.
The central double-orifice repair has been used in 260 patients (mean age, 56 +/- 14.3 years) over a period of 7 years. The mechanism responsible for mitral regurgitation was prolapse of both leaflets in 148 patients, prolapse of the anterior leaflet in 68, prolapse of the posterior leaflet with annular calcification or other unfavorable features in 31, and lack of leaflet coaptation for restricted motion or erosion of the free edge in 13. Degenerative disease was the cause of mitral regurgitation in 80.8% of the patients, rheumatic disease was the cause in 9.6%, endocarditis was the cause in 6.1%, and ischemic disease was the cause in 2.3%.
Hospital mortality was 0.7%, and the overall survival at 5 years was 94.4% +/- 2.59%. Thirteen patients required a reoperation (2 early postoperatively and 11 late during the follow-up), for an overall freedom from reoperation of 90.0% +/- 3.37% at 5 years. Freedom from reoperation was lower in patients with rheumatic valve disease and in patients who did not undergo an annuloplasty procedure.
The effectiveness and durability of the central double-orifice technique were assessed in this study. This type of repair can be a useful addition to the surgical armamentarium in mitral valve reconstruction.
Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Because such MR is related to increased leaflet tethering by displaced attachments to the papillary muscles (PMs), it is incompletely treated by annular reduction. We therefore addressed the hypothesis that such MR can be reduced by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. This was tested in 8 mitral valves: a porcine in vitro pilot with PM displacement and 7 sheep with acute inferobasal infarcts studied in vivo with three-dimensional (3D) echo to quantify MR in relation to 3D valve geometry.
In all 8 valves, PM displacement restricted leaflet closure, with anterior leaflet angulation at the basal chord insertion, and mild-to-moderate MR. Cutting the 2 central basal chordae reversed this without prolapse. In vivo, MR increased from 0.8+/-0.2 to 7.1+/-0.5 mL/beat after infarction and then decreased to 0.9+/-0.1 mL/beat with chordal cutting (P<0.0001); this paralleled changes in the 3D leaflet area required to cover the orifice as dictated by chordal tethering (r(2)=0.76).
Cutting a minimum number of basal chordae can improve coaptation and reduce ischemic MR. Such an approach also suggests the potential for future minimally invasive implementation.
We sought to compare mitral valve repair and replacement as treatments for degenerative mitral valve disease with coexisting ischemic heart disease. Specifically, we sought to (1) identify differences between patients undergoing repair and replacement, (2) determine whether the choice of mitral valve procedure affected survival after adjusting for those differences, and (3) discover which patients were predicted to benefit from mitral valve repair and which from replacement.
From 1973 to 1999, 679 patients (mean age, 67 +/- 9.1 years; 73% men) with degenerative mitral valve and ischemic heart diseases underwent combined coronary artery bypass grafting and either mitral valve repair (66%) or replacement (34%). Factors associated with repair and replacement were used for multivariable propensity matching. Risk factors for death were identified by means of multivariable, multiphase hazard-function analysis.
Patients more likely to undergo repair had isolated posterior chordal rupture (P <.0001) or more recent date of operation (P <.0001); those more likely to undergo replacement were older (P =.0003) or had bileaflet prolapse (P <.0001). Unadjusted survival at 30 days and 1, 5, and 10 years was 97%, 92%, 79%, and 59% after repair and 94%, 88%, 70%, and 37% after replacement. After adjusting for comorbid factors, the extent and effect of ischemic heart disease, and propensity score, the survival benefit of repair became evident after 2 years (P =.01). Eighty-nine percent of patients were predicted to benefit from repair.
In patients with degenerative mitral valve and ischemic heart diseases, mitral valve repair confers a survival advantage over replacement that becomes evident about 2 years after the operation.
Chronic ischemic mitral regurgitation (CIMR) is poorly understood and repair operations are often unsatisfactory. This study elucidates the mechanism of CIMR in an ovine model.
Sonomicrometry array localization measured the three-dimensional geometry of the mitral annulus and subvalvular apparatus in five sheep before and 8 weeks after a posterior infarction of the left ventricle that produced progressive severe CIMR.
End systolic annular area increased from 647 +/- 44 mm(2) to 1,094 +/- 173 mm(2) (p = 0.01). Annular dilatation occurred equally along the anterior (47.0 +/- 5.6 mm to 60.2 +/- 4.9 mm, p = 0.001) and posterior (53.8 +/- 3.1 mm to 68.5 +/- 8.4 mm, p = 0.005) portions of the annulus. The tip of the anterior papillary muscle moved away from both the anterior and posterior commissures by 5.2 +/- 3.2 mm (p = 0.021) and 7.3 +/- 2.2 mm (p = 0.002), respectively. The distance from the tip of the posterior papillary muscle to the anterior commissure increased by 11.0 +/- 5.7 mm (p = 0.032) while the distance from the tip of the posterior papillary muscle to the posterior commissure remained constant.
Progressive dilatation of both the anterior and posterior mitral annuli, increased annular area, and asymmetric ventricular dilatation combine to cause CIMR by distortion of mitral valve geometry and tethering of leaflet coaptation. Therefore complete ring annuloplasty may be superior to partial annuloplasty in the treatment of CIMR.
Complex mitral regurgitation (MR) jets can make repair challenging; edge-to-edge (Alfieri) repair augments the repertoire of repair techniques. Objectives of this study were to demonstrate causes of MR amenable to edge-to-edge repair and to determine safety, obstructive potential, and durability of edge-to-edge repair.
From January 1997 to October 2001, 224 patients underwent Alfieri repair. Indications included ischemic cardiomyopathy (n = 143, 64%), myxomatous disease (n = 31, 14%), dilated cardiomyopathy (n = 27, 12%), and hypertrophic obstructive cardiomyopathy (n = 14, 6%). Concomitant ring annuloplasty was performed in 188 patients (84%). Two additional patients had takedown of an Alfieri repair in the operating room for obstruction. Preoperative MR was 4+ in 109 patients (50%) and 3+ in 65 (30%). Postoperative and follow-up mitral gradient and return of MR were assessed using 396 transthoracic echocardiograms and longitudinal analyses.
Hospital mortality was 2% (5 of 224). Mitral valve mean gradient was low (3.7 mm Hg) and nonprogressive (p = 0.7), although peak gradient rose slightly, from mean 8.4 to 10.0 mm Hg (p = 0.01). During the first 3 postoperative months, absence of MR declined to 40%, and prevalence of 3+ MR increased to 14%, then rose slowly thereafter. Fourteen patients--12 within 2 years--underwent mitral valve reoperation, none for stenosis; 7 patients--6 within 2 years--underwent heart transplantation.
Alfieri mitral repair can be used in a variety of settings with a low risk of creating mitral stenosis. However, in ischemic MR, steadily increasing prevalence of moderately severe and severe regurgitation after edge-to-edge repair suggests other techniques are needed.
Percutaneous mitral valve procedures are under investigation as a novel method to treat mitral valve insufficiency with a catheter-based, closed heart, non-surgical approach. The technical opportunities, the expectations for the future and the implications for the conventional surgery are discussed.
The aim of this study was to assess the results of mitral valve (MV) repair in functional mitral regurgitation because of end-stage dilated cardiomyopathy (DCM).
Seventy-seven patients with end-stage idiopathic (26 patients) or ischemic (51 patients) DCM underwent MV repair for functional mitral regurgitation (3 to 4+/4+). Fifty-eight patients (75.3%) were in New York Heart Association class III, and 19 (24.6%) were in IV. In 23 patients (29.8%) with a coaptation depth <1 cm, an isolated undersized annuloplasty was used. In the remaining 54 (70.1%), with a coaptation depth > or =1 cm, the "edge-to-edge" technique was associated with the annuloplasty. In most of the cases (88.3%), a complete rigid/semirigid ring was used. Concomitant coronary artery bypass graft was performed in 39 patients (50.6%). Hospital mortality was 3.8% (3 of 77). Actuarial survival was 90.7+/-3.64%, and freedom from cardiac events was 81.8+/-7.96% at 2.7 years. At a mean follow-up of 18.4+/-9.8 months (range, 1 month to 5 years) New York Heart Association class improved from 3.4+/-0.4 to 1.4+/-0.6 (P<0.0001). Mitral repair failure (recurrence of MR > or =3+/4+) was documented in 7 patients (9%): 2 in the edge-to-edge (2 of 54, 3.7%) and 5 in the isolated annuloplasty group (5 of 23, 21.7%) (P=0.03). Freedom from repair failure at 1.5 years was 95.0+/-3.4% and 77+/-12.1%, respectively (P=0.04). The absence of the edge-to-edge was the only predictor of repair failure (P=0.03). When residual MR was absent or mild, a reverse left ventricular remodeling was clearly documented.
In patients with end-stage DCM, MV repair is feasible with low hospital mortality and important symptomatic improvement. The association of the edge-to-edge technique to the undersized annuloplasty can significantly improve the durability of the repair.
Residual or recurrent mitral regurgitation frequently occurs after mitral ring annuloplasty repair for ischemic mitral regurgitation (IMR), because annuloplasty primarily addresses annular dilatation. We describe a subvalvular repair technique addressing posterior papillary muscle (PPM) displacement.
Ten sheep had radiopaque markers placed on the left ventricle (LV) and mitral apparatus. A suture was anchored at the right fibrous trigone, passed through the PPM tip and LV wall, and exteriorized through a tourniquet (STRING-1). A second suture was anchored transmurally in the high septum (anterobasal LV wall) and passed through the PPM and LV wall (STRING-2). Reversible posterolateral ischemia was induced by temporarily occluding the proximal circumflex artery. Under open chest conditions, 3D marker coordinates were obtained with biplane videofluoroscopy at baseline and during acute ischemia before and after tightening of each STRING using transesophageal echocardiography to grade IMR. IMR decreased (mean+/-SEM, 2.0+/-0.1 to 1.2+/-0.1; P<0.05) when STRING-1 was tightened, did not change after tightening STRING-2 (2.3+/-0.1 to 2.3+/-0.1), and decreased after tightening both sutures (STRING-1+2, 2.3+/-0.2 to 1.3+/-0.2; P<0.05). STRING-1 and STRING-1+2 (STRING-1, 1.7+/-0.4 mm; STRING-2, 0.7+/-0.5 mm; STRING-1+2, 1.5+/-0.3 mm; P<0.05) resulted in significant PPM basal repositioning. Tightening of any STRING sutures did not affect anterior mitral leaflet excursion.
Basal repositioning of the PPM with STRING-1 reduced acute IMR without concomitant annular reduction. This technique may be a useful adjunct if residual IMR is likely after undersized ring annuloplasty.
This study sought to evaluate the clinical results of a percutaneous approach to mitral valve repair for mitral regurgitation (MR).
A surgical technique approximating the middle scallops of the mitral leaflets to create a double orifice with improved leaflet coaptation was introduced in the early 1990s. Recently, a percutaneous method to create the same type of repair was developed. A trans-septal approach was used to deliver a clip device that grasps the mitral leaflet edges to create the double orifice.
General anesthesia, fluoroscopy, and echocardiographic guidance are used. A 24-F guide is positioned in the left atrium. The clip is centered over the mitral orifice, passed into the left ventricle, and pulled back to grasp the mitral leaflets. After verification that MR is reduced, the clip is released.
Twenty-seven patients had six-month follow-up. Clips were implanted in 24 patients. There were no procedural complications and four 30-day major adverse events: partial clip detachment in three patients, who underwent elective valve surgery, and one patient with post-procedure stroke that resolved at one month. Three additional patients had surgery for unresolved MR, leaving 18 patients free from surgery. In 13 of 14 patients with reduction of MR to < or =2+ after one month, the reduction was maintained at six months.
Percutaneous edge-to-edge mitral valve repair can be performed safely and a reduction in MR can be achieved in a significant proportion of patients to six months. Patients who required subsequent surgery had elective mitral valve repair or intended replacement.
Perturbations of leaflet geometry are the final end point through which left ventricular (LV) ischemia causes incomplete mitral leaflet closure and resultant mitral regurgitation (MR). Geometric inconsistencies observed with valvular or subvalvular structural alterations raise several questions.
A new in-vitro LV flexible bag model was developed in order to visualize and analyze leaflet geometric changes under simulated pathological ischemic MR conditions.
Papillary muscle (PM) displacement and annular dilatation decreased leaflet coaptation length, leading to significant MR. Symmetrical PM displacement shifted the coaptation line towards the leaflet edges and created central gaps along this line. Asymmetric PM displacement generated diametrically uneven coaptation with a tent-shaped leaflet at the tethered PM side, while the leaflet bulged at the opposite side towards the left atrium.
Leaflet geometry during systole is affected by subvalvular structures. Asymmetric PM displacement, which may occur in regional or acute myocardial infarction, induces irregular deformation of the leaflet's coaptation line and, as a result, MR at the tethered side. Direct visualization of leaflet perturbation under these simulated pathological conditions may promote understanding of mechanisms present in ischemic MR.
Edge-to-edge mitral valve repair is usually performed in association with annuloplasty, with rare exceptions. We retrospectively analyzed the results of ringless edge-to-edge repair, particularly in view of minimally invasive and percutaneous approaches.
From November 1993 to December 2001, 81 patients underwent edge-to-edge mitral repair without associated annuloplasty. The cause was degenerative in most patients. In 32 patients the annulus was severely calcified. Type I lesions were present in 6 patients, type II lesions in 60 patients, and type III lesions in 15 patients. A double-orifice repair was done in 69 patients, and paracommissural repair was done in 12 patients. In 5 patients edge-to-edge repair was used as a rescue procedure.
There were 3 hospital and 4 late deaths, for a 4-year survival of 85% +/- 6.7%. At latest follow-up, 63 patients were in New York Heart Association classes I or II, and 9 patients were in classes III or IV. Nine patients required reoperation (89% +/- 3.9% overall freedom from reoperation at 4 years). Annular calcification was associated with a greater reoperation rate (77% +/- 22% vs 95% +/- 4.6% freedom from reoperation, P =.03). Intraoperative water testing and postrepair transesophageal echocardiography predicted late failure. Only 1 of 42 patients required reoperation in the follow-up period when annular calcification, rheumatic disease, or rescue procedure were not present as risk factors.
Our data confirm overall suboptimal results of the edge-to-edge technique when annuloplasty is not added to the repair. Annular calcification, rheumatic cause, and edge-to-edge repair done as a rescue procedure were associated with the worst outcome. Midterm results in selected patients encourage future developments in catheter-based edge-to-edge procedures.
Alfieri edge-to-edge mitral repair has been used clinically with ring annuloplasty to correct ischemic mitral regurgitation (IMR), but its efficacy without concomitant ring annuloplasty has not been described in this setting.
Seventeen sheep underwent implantation of 9 radiopaque markers on the left ventricle, 8 on the mitral annulus (MA), 1 on each papillary muscle (PM) tip, and 1 on the anterior and posterior leaflet edges near the anterior and posterior commissures. Alfieri repair was performed in 7 animals, and 10 were controls. Biplane videofluoroscopy and transesophageal echocardiography (TEE) were performed (open chest) before and continuously during left circumflex coronary artery occlusion to induce acute IMR. MA area (MAA), anterior (APM), and posterior (PPM) papillary muscle tip distances to midseptal MA ("saddle horn"), and distance of each leaflet marker to the mitral annular plane were calculated from 3-dimensional marker coordinates at end-systole (ES).
Severity of IMR was not different between groups (+1.9+/-0.7 versus +1.4+/-0.5 for Control and Alfieri, respectively; P=not significant [NS]). Mitral annular area (MAA; 21+/-15 versus 19+/-9%; P =NS) and septal-lateral (SL) annular diameter (12+/-6 versus 12+/-11%; P =NS) increased similarly during ischemia. While PPM-saddle horn distance increased in both groups (1.5+/-1.3 and 1.6+/-1.4 mm for Control and Alfieri, respectively; P<0.05 versus preischemia), APM-saddle horn distance increased in Control (1.0+/-1.2 mm; P=0.03) but not in the Alfieri animals (0.8+/-08 mm; P=0.07). Leaflet edge displacements from the annular plane during ischemia were similar in both groups.
Alfieri repair did not prevent acute IMR nor alter ischemic valvular or subvalvular geometric perturbations. Adjunct surgical procedures, such as ring annuloplasty, are also necessary.
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