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TATE-OF-THE-ART PAPER

ercutaneous Transcatheter Mitral Valve RepairClassification of the Technology

aul T. L. Chiam, MBBS,* Carlos E. Ruiz, MD, PHD†

ingapore; and New York, New York

urgical treatment of mitral regurgitation (MR) has evolved from mitral valve replacement (MVR) to

epair (MVRe), because MVRe produces superior long-term outcomes. In addition, MVRe can be

chieved through minimally invasive approaches. This desire for less invasive approaches coupled with

he fact that a significant proportion of patients—especially elderly persons or those with significant

omorbidities or severe left ventricular (LV) dysfunction, are not referred for surgery, has driven the

eld of percutaneous MVRe. Various technologies have emerged and are at different stages of investi-

ation. A classification of percutaneous MVRe technologies on the basis of functional anatomy is pro-

osed that groups the devices into those targeting the leaflets (percutaneous leaflet plication, percuta-

eous leaflet coaptation, percutaneous leaflet ablation), the annulus (indirect: coronary sinus approach

r an asymmetrical approach; direct: true percutaneous or a hybrid approach), the chordae (percutane-

us chordal implantation), or the LV (percutaneous LV remodeling). The percutaneous edge-to-edge

epair technology has been shown to be noninferior to open repair in a randomized clinical trial (EVER-

ST II [Endovascular Valve Edge-to-Edge REpair Study]). Several other technologies employing the con-

epts of direct and indirect annuloplasty and LV remodeling have achieved first-in-man results. Most

ikely a combination of these technologies will be required for satisfactory MVRe. However, MVRe is not

ossible for many patients, and MVR will be required. Surgical MVR is the standard of care in such pa-

ients, although percutaneous options are under development. (J Am Coll Cardiol Intv 2011;4:1–13)

2011 by the American College of Cardiology Foundation

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itral regurgitation (MR) is a common valvularbnormality, being present in 24% of adults withalvular heart disease and in 7% of the population75 years of age (1,2). Surgical intervention is

ecommended for symptomatic severe MR orsymptomatic severe MR with left ventricular (LV)ysfunction or enlargement (3). Treatment of se-ere degenerative MR has evolved from mitralalve replacement (MVR) to mitral valve repairMVRe) (3), because repair produces superior out-omes (4,5). For functional MR, however, theenefit of repair over MVR is less certain (6)

rom the *Department of Cardiology, National Heart Centre, Singa-ore, Singapore; and the †Department of Cardiac and Vascular Inter-entional Services, Lenox Hill Heart and Vascular Institute of Nework, New York, New York. Dr. Chiam reports that he has no

elationships to disclose. Dr. Ruiz is a consultant for CoreValve.

aanuscript received June 14, 2010; revised manuscript received Septem-

er 8, 2010, accepted September 17, 2010.

With increased understanding of the hetero-enic pathophysiology of MR, cardiac surgeonsave developed various techniques that increase the

ikelihood of successful repair (7). Mitral valveepair can also be achieved through minimallynvasive approaches (8,9). This desire for lessnvasive approaches coupled with the fact that aignificant proportion of patients—especially el-erly persons or those with significant comorbidi-ies or severe LV dysfunction—are not referred forurgery (10) has driven the field of percutaneous

VRe. Various technologies have emerged and aret different stages of investigation.

ercutaneous Approaches toitral Valve (MV) Therapies

he MV is just one of the elements of the mitral
pparatus, and as such pathologies affecting the

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J A N U A R Y 2 0 1 1 : 1 – 1 3

Chiam and Ruiz

Percutaneous Mitral Valve Repair

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nnulus (mitral annulus [MA]), leaflets, papillary muscle,hordae tendineae, LV, and left atrium (LA) can all producer contribute to MR. The functional anatomy and classifi-ation of MR have been reviewed recently (7) and would note further discussed. Surgical techniques are primarilyimed at correcting the culprit mechanism(s) (e.g., pro-apsed leaflet, annular dilation) that lead to MR (7), and aombination of techniques may be used to obtain the bestutcome. These surgical techniques can be broadly classifiednto those aimed at the leaflets, MA, commissures, chordae,apillary muscles, and LV. Current percutaneous technol-gies for MVRe have been developed on the basis of somef these surgical principles.These technologies have been previously grouped into

hose acting on the leaflets, direct annuloplasty or indirectnnuloplasty (via the coronary sinus [CS]), and chamberLV) remodeling (11–15). A modified classification ofercutaneous MVRe technology according to functionalnatomy and device action is proposed (Table 1). This

might facilitate more precise de-scription of the current devicesand accommodate emergingtechnologies.

Percutaneous LeafletPlication (Edge-to-EdgeLeaflet Repair)

Principle. The leaflet plicationtechnology is based on the sur-gical Alfieri technique (16),which brings the anterior andposterior leaflets together with asuture, creating a “double ori-fice” MV. This re-establishes

eaflet coaptation, thereby reducing MR. This technique isost suitable for degenerative MR, although it could be

mployed in functional MR.evices. The MitraClip (Abbott Vascular, Santa Clara, Cal-

fornia) system uses a steerable catheter to deliver a clip to thenterior leaflet and posterior leaflet via transseptal accessFig. 1). The safety and feasibility study (EVEREST I [En-ovascular Valve Edge-to-Edge REpair Study]) (17) showedhat, in 107 patients, procedural success (post-procedure MR

2�) was achieved in 74% with �1% in-hospital mortality17). At 1-year, freedom from death, MV surgery or MR �2�as 66%. Freedom from death and freedom from surgery were0.1% and 76.3% at 3 years, respectively. No clip embolized,lthough partial clip detachment occurred in 10 patients (9%).ubsequently, 32 patients required surgery for MR; repair—hen planned—was possible in 84%, demonstrating that

urgical options were preserved (17,18).Data from the EVEREST II study, randomizing Mitra-

bbreviationsnd Acronyms

S � coronary sinus

IM � first-in-man

A � left atrium

V � left ventricle

A � mitral annulus

R � mitral regurgitation

S � mitral stenosis

V � mitral valve

VR � mitral valveeplacement

VRe � mitral valve repair

lip versus surgical repair, were recently presented (Amer- d

can College of Cardiology 2010). Patients (n � 279) withymptomatic severe MR or asymptomatic severe MR withV dysfunction were randomized in a 2:1 (device: surgery)

ashion. Freedom from combined end point of death, MVurgery or reoperation �90 days after index procedure, and

R �2� at 1 year was 72.4% and 87.8% in the device andurgical groups, respectively, meeting the noninferiorityypothesis. The safety end point (all predefined adversevents plus blood transfusions �2 U) was superior in theevice group (9.6% vs. 57% for surgery). The MitraCliphus seems to be an alternative option for selected patients.

The Mobius device (Edwards Life Sciences, Irving,alifornia) used a suture to create a double orifice MV.espite feasibility in the animal model, initial human

xperience was limited by suture dehiscence and technicalifficulties (19), and the program has been abandoned.The MitraFlex (TransCardiac Therapeutics, Atlanta,eorgia), which deploys a clip to the leaflets via the

ransapical route, is undergoing pre-clinical testing (thisevice also allows an artificial chord to be implanted duringhe same procedure).imitations. The major limitation of this percutaneousechnology is that the surgical Alfieri technique is typicallysed with an annuloplasty, because results without annulo-lasty have been suboptimal with significant rates of recur-ent MR and need for reoperation (20), especially inschemic MR (21) or if annular calcification is present (20).

owever, in a small group of well-selected patients, 90%reedom from recurrent MR �2� or reoperation at 5 yearsould be achieved (22). Another limitation is the possibilityf causing iatrogenic mitral stenosis (MS) (7), althougherrmann et al. (23) reported no significant stenosis in 96

atients with successful MitraClip(s) implanted.

eaflet Ablation

rinciple. Radiofrequency energy is delivered to the leaf-et(s) to effect structural (fibrosis) or functional (reduced

otion) alteration. This technology is designed to targetegenerative MR.evice. The Thermocool irrigation ablation electrode (Bio-

ense Webster, Inc., Diamond Bar, California) is a radiofre-uency ablation (RFA) catheter that is delivered via femoralrtery access retrograde into the LV. The catheter is placed inontact with the anterior leaflet, and RFA is delivered, causingcarring and fibrosis and reduced leaflet motion. Proof-of-oncept was demonstrated in an animal study (24).imitations. Scarring and fibrosis from the RFA might not berecise, resulting in too-long or too-short post-ablation leafletith residual or even worsening MR. Leaflet perforation and
amage to adjacent cardiac structures might occur.

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eaflet Space Occupier

rinciple. A device acting like a “buoy” is positioned acrosshe MV orifice to provide a surface against which the leafletsan coapt, reducing MR. This could be applied to degen-rative or functional MR.evice. The Percu-Pro device (Cardiosolutions, Stough-

Table 1. Percutaneous MVRe and MVR Technologies

Site of Action Mechanism of Action Device

Percutaneous

Leaflets Edge-to-edge (leaflet plication) MitraClip

MitraFlex

Space occupier (leafletcoaptation)

Percu-Pro

Leaflet ablation Thermocool

Annulus Indirect annuloplasty

● Coronary sinus approach(CS reshaping)

Monarc

Carillon

Viacor

● Asymmetrical approach St. Jude device

NIH-Cerclage technology

Direct annuloplasty

● Percutaneous mechanicalcinching

Mitralign

Accucinch GDS

Millipede ring system

● Percutaneous energy-mediated cinching

QuantumCor

ReCor

● Hybrid Mitral solutions

MiCardia

Chordal implants Transapical

● Artificial chord Neochord,MitraFlex

Transapical-Transseptal

● Artificial chord Babic

LV LV (and MA) remodeling Mardil-BACE

Percutaneous

Valve implants Right mini-thoracotomy Endovalve-Herrmann prosth

Transapical Lutter prosthesis

Transseptal CardiaQ prosthesis

CS � coronary sinus; FIM � first-in-man; LV � left ventricle/ventricular; MA � mitral annulus; MR �

NIH � National Institutes of Health.

on, Massachusetts) consists of a polyurethane-silicone b

olymer space-occupying buoy that is anchored at thepex through the MV (Fig. 2) acting as a “spacer” in theitral orifice. A transseptal approach is required to

mplant the anchor in the apex. It is undergoing phase 1rial.

imitations. Possible limitations are thrombus formation onhe device, residual MR, or iatrogenic MS (restricted inflow

Status Major Limitations

Technologies

Randomized trial data presented Results when performed alone may not bedurable. Possibility of iatrogenic MS.

Pre-clinical development As for MitraClip

Phase 1 trial Device thrombus formation. Residual MR oriatrogenic MS.

Animal models Scarring not precise with residual MR.Leaflet/cardiac structure perforation.

FIM results. Feasibility studyongoing.

CS at a distance from MA. Possibility ofcoronary artery compression.

FIM results. Feasibility studycomplete.

As above

FIM results. Feasibility studyongoing.

As above

Animal models CS at a distance from MA. Unequal tensionon LA or MA. Device fracture or erosion, andthrombus formation.

Animal models CS at a distance from MA. Unequal tensionon LA or MA.

FIM results Only posterior MA cinching.

FIM results As above

Pre-clinical development Feasibility and stability of fixation unknown

Animal models Scarring not precise. Possible residual MR oriatrogenic MS. Risk of cardiac structureperforation.

Pre-clinical development As above

Pre-clinical development Not true “percutaneous” technique


Pre-clinical development Residual leaflet prolapse or restriction withresidual MR. Thrombus formation.


Temporary human implant Requires mini-thoracotomy. Long-termeffects unknown.

Technologies

Animal models Anchoring challenges. LV outflowobstruction. Paravalvular leaks.

Animal models As above


egurgitation; MS � mitral stenosis; MVR � mitral valve replacement; MVRe � mitral valve repair;

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nnuloplasty—Indirect

his approach mimics surgical annuloplasty rings, which areommonly used for repair of both degenerative and functional

R. Because surgical annuloplasty necessitates cardiac bypass, it issually performed with another indication such as coronary arteryypass graft (25). The percutaneous devices might thus offer anlternative for those at excessive surgical-risk or who do not requirenother concomitant cardiac surgical procedure. Several percuta-eous devices are in clinical testing, mainly for functional MR.

S Approach (CS Reshaping)

rinciple. This approach involves implantation of devices withinhe CS with the aim of “pushing” the posterior annulus anteriorly,hereby reducing the septal-lateral (anterior-posterior) dimensionf the MA. This has been demonstrated in surgical data tomprove leaflet coaptation and decrease MR (26).evices. The Monarc (previously Viking) system (Fig. 3) (Ed-ards Lifesciences) consists of an outer guide catheter, a smallerelivery catheter, and a nitinol implant. The implant has 3ections: distal and proximal self-expanding anchors, and a spring-

Figure 1. MitraClip Device

Picture of the MitraClip device (left), the MitraClip deployed on the mitral valve le

Figure 2. Percu-Pro Device

Diagram showing transseptal implantation of the Percu-Pro (Cardiosolutions, S
face for leaflet coaptation (right).
ike “bridge” that has shortening forces. This draws the proximalS and distal great cardiac vein closer, indirectly displacing theosterior annulus anteriorly. The Viking device produced an initialavorable effect on MR, although device fracture and recurrence of

R occurred, and the feasibility study was stopped (27). Thee-engineered device (Monarc) has a reinforced bridge segment.he phase 1 trial (Evolution) of functional MR with the Monarcevice demonstrated implantation success in 82% (59 of 72atients), with 13 failures (18%) due to tortuous anatomy ornappropriate CS dimensions. Three myocardial infarctions oc-urred due to coronary artery compression (1 received coronarytenting, 1 treated medically, 1 fatality). Event-free survival was1%, 72%, and 64% at 1 year and 2 and 3 years, respectively (Janarnek, European Society of Cardiology Congress 2010, Stock-

olm, Sweden). A larger Evolution II study is ongoing.The Carillon Mitral Contour System (Cardiac Dimension,

nc., Kirkland, Washington) (Fig. 4) consists of self-expandableitinol distal and proximal anchors connected by a nitinol bridgehat are placed in the great cardiac vein and proximal CS via aatheter-based system. Tension applied on the system results ininching of the posterior periannular tissue and deflection of the

(middle), and the tissue bridge with a “double-orifice” mitral valve (right).

ton, Massachusetts) “spacer” (left, middle), and the “spacer” providing a sur-
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osterior MA anteriorly. A feasibility study showed modestlyeduced septal-lateral dimension and MR when placed tempo-arily (28). Slippage of the anchors occurred, requiring deviceodification. Data from the AMADEUS trial (CARILLONitral Annuloplasty Device European Union Study) using theodified CARILLON XE device (Cardiac Dimension, Inc.) in

unctional MR due to dilated cardiomyopathy demonstratedmplantation success in 62% (30 of 48 patients), with mean 1rade reduction of MR (although it is uncertain whether thisould be clinically meaningful). Implantation could not be

chieved in 18 patients (38%) due to access issues (CS dissection/erforation), insufficient MR reduction, and coronary artery com-ression. Coronary arteries were crossed frequently (36 of 43mplant attempts), although device was recaptured in only 17%here compromise was significant (29).The Viacor percutaneous transvenous mitral annuloplasty de-

ice (Viacor, Inc., Wilmington, Massachusetts) (Fig. 5) usesitinol rods of varying length and stiffness, delivered via a cathetero the CS. This exerts outward force resulting in anterior displace-ent of the posterior annulus. Temporary human implantationas feasible. Subsequent permanent implantation was achieved

lthough successful only in a small proportion (9 of 27 patients)30). Problems encountered were access issues, unsuccessful MReduction, unstable device, and technical delivery difficulties. Dur-

Figure 3. Monarc Device

The Monarc (Edwards Life Sciences, Irving, California) device (top) compris-ing proximal (larger) and distal anchors and a bridge, and diagrammaticalrepresentation after implantation in the coronary sinus.

ng the study, the device remained in only 4 patients (17%) (1

evice fracture, 3 underwent surgical annuloplasty, 1 died 3onths after implant) (30).imitations. There are major limitations to the use of CSeshaping. The technique exploits the proximity of the CS to the

A. However, surgical anatomy suggests that the CS is locatedehind the LA wall at a significant distance from the MA (31,32).he projection of CS annuloplasty covered just over one-half of

he total MA perimeter (32). Similarly with computed tomogra-hy angiography, there was significant variability in the relation ofhe CS to MA, and this distance was increased in severe MR withnnular dilation (33,34). These CS devices likely shrink the MAnly indirectly by traction on the LA wall. The annulus might inact continue to dilate, reducing device effectiveness.

Furthermore, there is a risk that these devices might compresscoronary artery. It has been demonstrated that a diagonal or

amus branch crossed between the CS and MA in 16% ofatients, whereas it was between 64% and 80% for the leftircumflex artery (31–34). Therefore, anatomic assessment of theS, coronary artery, and MA relationship is mandatory before

onsidering these devices.Other limitations include significant MA calcification, presence

f CS pacing leads, coronary venous branch point variability,oronary venous system size constraints (risk of CS perforation),nd structural leaflet abnormalities. This approach might theoret-cally jeopardize future attempts at implanting cardiac resynchro-

Figure 4. Carillon XE Device

The Carillon XE (Cardiac Dimension, Inc., Kirkland, Washington) device(top), comprising proximal (larger) and distal anchors and a bridge.Sequence of implantation with the delivery sheath in the coronary sinus(middle left), removal of sheath (middle right, bottom left), and only
device remaining (bottom right).

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ization devices, although initial experience has been reassuring35).

symmetrical Approach

rinciple. This group of devices uses the proximity of the CS tohe annulus to try to reshape the MA but in addition exert tractionorce on another portion of the LA or right atrium, resulting insymmetrical forces. The aim is to reduce septal-lateral dimensionnd decrease MR.evices. The percutaneous septal sinus shortening (PS3) system

Ample Medical, Foster City, California) employed a CS anchorositioned behind posterior leaflet, a bridge (cinching wire) con-ecting the CS anchor to an atrial septal anchor (Amplatzer PFOccluder [AGA Medical, Plymouth, Minnesota]). Tension on theridge reduced septal-lateral dimension and reduced MR (36).urther device development, however, has been abandoned.Another device by St. Jude Medical (Minneapolis, Minnesota)

Fig. 6) implanted in animal models consists of 4 helical anchors,loading spacers, a tether rope, and a locking mechanism. The

istal pair of anchors is delivered via the CS into the LVyocardium near the posterior leaflet scallop. The proximal pair

s implanted via the right atrium into the postero-medialrigone. The 2 pairs of anchors are connected by a cable toffect cinching of the postero-medial MA. Dynamic shorten-ng can be performed manually and reversibly, and the locking

echanism is a self-retracting, nitinol structure that maintains

Figure 5. Viacor Device

The Viacor (Viacor, Inc., Wilmington, Massachusetts) PTMA rods (top left), acceafter full implantation of the rods (bottom right) in the coronary sinus.

inched load (37). M

The National Institutes of Health cerclage technology directs auidewire via the CS into the first septal perforator of the greatardiac vein and, under imaging, across the myocardium toe-enter a right heart chamber. It is ensnared and exchanged for auture and tension-fixation device. Initial animal models haveroved promising with success in reducing MR (38).imitations. The major drawbacks of this technology are: 1) theS might not be in the same plane as the MA (true annuloplastyight not take place); and 2) unequal tension exerted on the CS

r LA, with unknown long-term consequences. There is aheoretical risk of device erosion or fracture and possible thrombusormation on the connecting cable.

nnuloplasty—Direct:ercutaneous Mechanicalinching Approach

rinciple. This technology reshapes the MA directly withoutsing the CS, approaching the MA from the LV or the LA side.utures or some other device are implanted onto the MA itselfnd used to directly “cinch” the MA. These technologies might beble to address the potential limitations of the indirect annulo-lasty method and would be most useful for functional MRalthough it could be employed in degenerative MR).evices. The Mitralign device (Mitralign, Tewksbury, Massa-husetts) (Fig. 7) gains access to the annulus from the transven-ricular approach. Anchors are placed directly on the posterior

the coronary sinus (bottom left), introduction of the rods (top right), and
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inch the MA. Retrograde LV access to the periannular space haseen achieved reliably with successful first-in-man (FIM) resultsunpublished data).

The Accucinch Annuloplasty System (Guided Delivery Sys-ems, Santa Clara, California) uses a transventricular approach andas FIM results (unpublished data). The posterior annulus isinched circumferentially from trigone to trigone (Fig. 8), withmprovement in MR.

The Millipede system (Millipede, LLC, Ann Arbor, Michi-an) involves placement of a novel repositionable and retrievablennular ring with a unique attachment system via percutaneoustransseptal) or minimally invasive methods.

nnuloplasty—Direct:ercutaneous Energy-Mediatedinching Approach

rinciple. Heat energy is applied to the MA, causingcarring and shrinkage of the MA.evices. By the transatrial (transseptal) route, the Quan-

umCor (QuantumCor, Lake Forest, California) deviceFig. 9) effects direct annuloplasty by use of radiofrequencynergy to cause scarring and constriction of the MA. It hasloop tip that contains electrodes and thermocouples to

egulate the amount of energy delivered. This device haseen tested in animal models with reduction of MA

Figure 6. St. Jude Device

The St. Jude Medical device (St. Jude Medical, Minneapolis, Minnesota)(bottom left arrow denotes distal anchors near P2, bottom right arrowdenotes proximal anchors near the postero-medial trigone).

istances and nonischemic MR (39). c

The ReCor (ReCor, Paris, France) device delivers high-ntensity focused ultrasound circumferentially and perpen-icularly to the catheter shaft to induce tissue heating andollagen (and thus MA) shrinkage.imitations. The limitation of the Mitralign and Accucinchevices is that only the posterior MA is cinched. Optimalurgical correction is currently thought to be obtained byerforming an annuloplasty with a complete rather than aartial ring (32), because the intertrigonal distance is not fixeds previously believed (7). The Millipede system overcomeshis issue, but feasibility and stability of annular fixation isnknown. Scarring induced by the QuantumCor and Recorevices might not be precisely controlled, and over-constrictionith resultant MS or under-correction with residual MR could

onceivably occur. Damage or perforation of neighboringardiac structures including the CS is possible, although thisas not observed in animal models (39).

nnuloplasty—Direct:ybrid Approach

rinciple. An annuloplasty ring is implanted surgically andan be subsequently adjusted via transseptal access if MRecurs or worsens.evices. The Adjustable Annuloplasty Ring (MitralSolu-

ions, Fort Lauderdale, Florida) (Fig. 10) is implantedurgically and can be adjusted with a mechanical rotatingable, whereas the Dynamic annuloplasty Ring SystemMiCardia, Inc., Irving, California), which recently hadIM results, is adjusted with radiofrequency energy.imitations. Although this approach seems an effective way ofustomizing device size-shape to each patient under real-lifeoading conditions, initial surgical implantation is required.herefore, these technologies are more of a hybrid technique.

t is conceivable that they might evolve into true percutaneousechnologies. Both are in pre-clinical development.

hordal Implantation

rinciple. Synthetic chords or sutures are implanted eitherrom a transapical or transseptal approach and anchorednto the LV myocardium at one end, with the leaflet at thether. The length of the chord is then adjusted to achieveptimal leaflet coaptation and reduce MR. This approachould be mainly for degenerative MR.evices. There are 3 devices currently in development: the

ransapically delivered MitraFlex (TransCardiac Therapeu-ics) and NeoChord (Neochord, Inc., Minnetonka, Minne-ota) devices, and the transapical-transseptal route of theabic device (Fig. 11). The MitraFlex and Neochordevices place an anchor in the inner LV myocardium andnother on the leaflet via a transapical approach and connecthe 2 with a synthetic “chord.” In the Babic device, 2
ontinuous suture tracks are created from the LV puncture


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Figure 7. Mitralign Device

Figures showing the Mitralign device (Mitralign, Tewksbury, Massachusetts) gaining access via the left ventricle (top left), placement of anchors on the posterior
mitral annulus (top right, bottom left), and after cinching (bottom right).
Figure 8. Accucinch Annuloplasty System

Figure (left) showing action of the Accucinch device (Guided Delivery Systems, Santa Clara, California) and animal model (right) of the deployed Accucinch sys-
tem (arrows denote suture along the posterior annulus).

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ite through the puncture of the target leaflet and arexteriorized via the transseptal route. A pledget is apposednto the exteriorized venous sutures and anchored onto thetrial side of the leaflet by retracting the guiding suturesrom the epicardial end. A polymer tube is then interposedetween the leaflet and free myocardial wall and secured athe epicardial surface by an adjustable knob.imitations. Possible problems that might be encoun-ered with this technology are residual leaflet prolapse

Figure 9. QuantumCor Device

The QuantumCor device (QuantumCor, Lake Forest, California) (left) and devic

Figure 10. Adjustable Annuloplasty Ring System

The Adjustable Annuloplasty Ring (MitralSolutions, Fort Lauderdale, Florida) (top left); th

artificial chords too long) or leaflet restriction (chordsoo short) and residual MR (7) and device thrombusormation.

V Remodeling

rinciple. A device is used to reduce the anterior–posteriorimension of the LV. This indirectly decreases the septal-

ateral annular distance and also brings the LV papillary

lied to the mitral annulus via the transseptal approach (right).

e connecting cable (top right). The cable connected to the ring (bottom).

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uscles closer to the leaflets. This approach seems suitableainly for functional MR due to ischemic or cardiomyopathic

tiologies.The percutaneous iCoapsys technology was based on the

oapsys surgical system (Myocor, Maple Grove, Minnesota),hich places pads on either side of the LV with a cord passing

hrough the LV cavity to apply tension to the MA and basalV wall, moving the posterior leaflet to better coapt with thenterior leaflet. Surgical data demonstrated implantationafety, reduction in MR, and positive LV remodeling (40).

Figure 11. Transcatheter Chordal Implants

The MitraFlex device sheath (TransCardiac Therapeutics, Atlanta, Georgia) (top(top right); the NeoChord device (Neochord, Inc., Minnetonka, Minnesota) imp

lthough transpericardial percutaneous device implantation n

ia a sub-xiphoid approach was feasible in animal models (41),evice development has been discontinued.The Mardil-BACE (Mardil, Inc., Morrisville, North Caro-

ina) (Fig. 12) device requires a mini-thoracotomy but ismplanted on a beating heart. A silicone band is placed aroundhe atrioventricular groove with built-in inflatable chamberslaced on the MA. This reshapes the MA for better leafletoaptation and can be remotely adjusted after implantation. Nooronary artery compromise was shown in animal models, androof-of-concept was demonstrated in 15 patients, although

clip for leaflet plication (top middle), and artificial chord implantationfrom a transapical approach (middle); the Babic device (bottom).

left),

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imitations. There are sparse clinical data, and longer-termutcomes and adverse events are unknown.

arget Patient Populations

espite the enthusiasm generated by these emerging devices, its important to consider what patient populations are suitable

Figure 12. Mardil-BACE Device

The Mardil-BACE device (Mardil, Inc., Morrisville, North Carolina) consists ofa silicone band with inflatable chambers implanted around the atrioventric-ular groove.

Figure 13. Endovalve-Herrmann Prosthesis

The Endovalve-Herrmann prosthesis (top right), loaded in the delivery sheath (top l

or these technologies. The 2 etiologies of MR most amenableo surgical repair are degenerative and functional. Annuloplastys the main technique used in functional MR, whereas leafletepair is also usually performed in degenerative MR.

In the EuroHeart survey, degenerative and functionaltiologies accounted for 61% and 7%, respectively (2). Fromglobal perspective, however, rheumatic disease (which haslow probability of repair) will take on greater prominence

up to 50%) (42).Despite numerous surgical techniques and performance

nder direct vision, repair was performed in just underne-half of patients with MR who required surgery in the.S. and Europe (2,43), with unfavorable anatomy, absencef surgical expertise, and failure of conservative surgeryeing the major reasons (2). In addition, certain pathologiesrheumatic, endocarditic, inflammatory, and so forth) areften not repairable. Therefore, current percutaneous op-ions might be useful only in a selected patient pool. Theeed for a cautious approach to percutaneous MVRe isurther emphasized by the excellent results of surgical repairnd the low perioperative mortality (44).

ercutaneous MVR

combination of percutaneous techniques will most likelye needed if results comparable to surgery are expected.espite the armamentarium available to surgeons and the

ncreasing preference for repair, in a significant proportion

eft), and sequence of implantation (bottom left and right).

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f patients, surgical MVRe is not possible or fails, and MVRs required (45).

In the future, the novel technology of percutaneous MVRight become a possible alternative in a selected group of

atients with a low probability of successful repair. However,he challenges are formidable. The MA has an asymmetricaladdle shape, and different anchoring designs might be re-uired for different MR etiologies. Left ventricular outflowbstruction might occur due to retained native valve tissue.aravalvular leaks might also pose a problem.There are 3 devices in development. The Endovalve-errmann prosthesis (Endovalve Inc., Princeton, New

ersey) (Fig. 13) is implanted from the LA side via a rightini-thoracotomy on a beating heart. The device is a

oldable nitinol structure that attaches to the native valveith specially designed grippers, is fully valve sparing,

nd repositionable before release. Animal models haveeen successful, and a true percutaneous version islanned. The Lutter prosthesis, a nitinol stent-valve, haseen implanted transapically in porcine models (46). TheardiAQ (CardiAQ Valve Technologies, Inc., Winches-

er, Massachusetts) prosthesis (Fig. 14) is in pre-clinicalevelopment and is delivered transseptally. Given theomplexities involved with this approach, further im-rovements to these technologies will be required beforelinical testing.

onclusions

he field of percutaneous transcatheter MVRe is evolvingxponentially. These emerging technologies can be classifiedy their site of action and device mechanism. The proposedlassification is based on therapies aimed at the leafletsleaflet plication, leaflet coaptation, leaflet ablation), annu-oplasty (indirect: CS approach or asymmetrical approach;

Figure 14. CardiAQ Prosthesis

The CardiAQ (CardiAQ Valve Technologies, Inc., Winchester, Massachusetts) pro(middle) and superior (right) surfaces of the mitral annulus.

nd direct: true percutaneous or hybrid), percutaneous

hords, and LV remodeling. Percutaneous edge-to-edgeeaflet repair has been shown to be noninferior to surgery in

randomized trial. Several other technologies—includingarious direct and indirect annuloplasty and LV remodelingevices—have achieved first-in-man results or are in pre-linical testing. Most likely a combination of these technol-gies will be required for satisfactory MVRe. However, forany patients repair will not be possible, and MVR will be

equired. Although there are significant challenges, severalercutaneous MVR prototypes are already in development.

eprint requests and correspondence: Dr. Carlos E. Ruiz, Lenoxill Heart and Vascular Institute, 130 East 77th Street, Nework, New York 10021. E-mail: [email protected].

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ey Words: catheter � mitral regurgitation � mitral valve �
ercutaneous � surgery.
http://www.sts.org/documents/pdf/Spring2005STS-ExecutiveSummary.pdf

http://www.sts.org/documents/pdf/Spring2005STS-ExecutiveSummary.pdf

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