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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3590_Библиотеки_им_академика_М_И_Перельмана
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Abstract: Percutaneous balloon mitral valvuloplasty (PBMV) is a safe and effective treatment
modality for selected patients with severe symptomatic mitral stenosis. However, the success of
this procedure relies on excellent understanding of indications of the procedure and the contemporary equipment and techniques utilized, which are the focus of this chapter.
Key words: Mitral stenosis, balloon valvuloplasty, rheumatic fever, mitral regurgitation.
CHAPTER 15
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Percutaneous Edge-to-Edge
Mitral Valve Repair Using the
MitraClip
Sidakpal Panaich Guy Reeder
Introduction
Mitral regurgitation (MR) is the most common valvular regurgitant abnormality, increasing in
prevalence with age and affecting approximately 4 million people in the United States alone.
Severe MR eventually leads to left ventricular (LV ) dilation and dysfunction resulting in heart
3
failure.
Although surgical mitral valve (MV) repair or replacement remains the first-line treatment for MR, a significant fraction of patients are poor surgical candidates
surgery. Such patients encounter increased morbidity and mortality, approaching 50% at 5 years.
Percutaneous edge-to-edge transcatheter mitral valve repair (TMVR) (also known as the Mitra-
Clip® system) provides a durable alternative in severe (31) MR and was approved by the Food
and Drug Administration (FDA) in October 2013 for prohibitive-risk patients with primary
MR. Recently published results of the Cardiovascular Outcomes Assessment of the MitraClip®
Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation (COAPT) trial demonstrated the benefit of this technology in secondary MR in terms of lower
hospitalization rates and all-cause mortality within 24 months of follow-up. This chapter will
review the indications and procedural details, as well as troubleshooting for MitraClip®.
®
4
and are thus denied
1,2
5
Evidence and Indications
The EVEREST II (Endovascular Valve Edge-to-Edge Repair of Mitral Regurgitation Study)
trial randomized patients to either surgical or TMVR (MitraClip®).
study demonstrated surgery to be superior in terms of efficacy (composite of survival and freedom
from recurrent MR), primarily driven by higher rates of repeat intervention for MV dysfunction
in the MitraClip® arm at 1 year. MitraClip® therapy, on the other hand, had a better safety outcome and compared favorably in terms of freedom from heart failure symptoms, improvement in
quality of life (QoL), and LV reverse remodeling parameters. At 5 years, there was again no difference in mortality between the surgical and percutaneous arms with similar reduction in New
York Heart Association (NYHA) class.
Clip® in terms of repeat interventions for residual MR between 1 and 5 years. Additional data
from follow-up registries that included higher-risk patients further corroborated significant reduction in MR, improvement in LV dimensions and heart failure symptoms, and reduction in heart
failure hospitalizations at 12 months after the MitraClip® procedure. According to the 2014 valvular disease guidelines, TMVR may be considered for severely symptomatic patients (NYHA
class III to IV) with chronic severe primary MR (stage D) who have favorable anatomy for the
160
6
The primary results of the
7
There was also no difference between surgery and Mitra-
15—PERCUTANEOUS EDGE-TO-EDGE MITRAL VALVE REPAIR USING THE MITRACLIP® 161
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Fig. 15.1 Degenerative mitral valve disease with large flail posterior leaflets and severe mitral regurgitation in
two separate patients (top row—patient 1; bottom row—patient 2).
repair procedure and a reasonable life expectancy, but who have a prohibitive surgical risk because
of severe comorbidities and remain severely symptomatic despite optimal medical therapy for heart
failure (class IIb, level of evidence: B) (Fig. 15.1).
8
The EVEREST II trial primarily included patients with primary MR. However, in a post hoc
analysis involving a small subgroup of patients with secondary MR, MitraClip® was noninferior
to surgery in terms of freedom from death, operation for MV dysfunction, or recurrent 3 MR
9
grade.
Previous data have demonstrated lack of survival benefit and high rate of MR recurrence
after surgical repair in patients with LV dysfunction. Given that the majority of secondary MR
patients are managed medically, this represents a large group that could potentially benefit from
a low-risk transcatheter procedure. Secondary MR represents a larger proportion of patients being treated with the MitraClip® in Europe
10–12
and constituted 77% of the patients in the ACCESS EU (ACCESS-Europe, A Two-Phase Observational Study of the MitraClip® System in
Europe) registry.
11
In fact, the European Society of Cardiology (ESC) Heart Failure and ESC/
European Association for Cardio-Thoracic Surgery (EACTS) valvular disease guidelines in 2012
both recommended percutaneous MV repair for patients with symptomatic severe secondary MR
despite optimal medical therapy (including cardiac resynchronization therapy if indicated) with
anatomic suitability who are judged inoperable or at high surgical risk by a team of cardiologists
and cardiac surgeons, and have a life expectancy greater than 1 year (class IIb, level of evidence:
13
C).
The results of two randomized trials evaluating the role of MitraClip® in secondary MR
were recently published. The French MITRA-FR study showed no difference in the rate of death
or unplanned hospitalization for heart failure at 1 year between medical therapy and medical
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therapy plus MitraClip®. However, the COAPT trial demonstrated significantly lower hospitalization rates (hazard ratio: 0.53; 95% confidence interval [CI], 0.40 to 0.70; P ,0.001) and allcause mortality (hazard ratio: 0.62; 95% CI, 0.46 to 0.82, P ,0.001) at 24 months in patients
with secondary MR who received MitraClip® in addition to guideline-directed optimal medical
therapy. Larger sample size, longer follow-up, more stringent adherence to guideline-directed
therapy, and higher success rates with more durable results were some of the plausible reasons for
the benefit seen in COAPT as opposed to the MITRA-FR study.
Preprocedural Planning
Transthoracic echocardiography (TTE) is a good first modality to evaluate cardiac function and
MR severity. However, a transesophageal echocardiogram (TEE) is important to define mitral
pathophysiology, MR severity, and anatomic suitability for successful TMVR (see Fig. 15.1 and
Fig. 15.2). Primary MR includes patients with intrinsic abnormalities of the MV, such as prolaps-
ing or flail leaflets due to myxomatous degeneration or fibroelastic deficiency. Secondary functional MR (FMR) is a consequence of LV enlargement and dysfunction due to ischemic or
nonischemic mechanisms, which results in mitral annular dilation and restricted/tethered leaflets.
The EVEREST inclusion criteria for MitraClip® therapy included a flail gap of ,10 mm, flail
length of ,15 mm, and, for secondary MR, a coaptation gap of ,2 mm and coaptation depth of
,11 mm. Moreover, most of the patients included in the trial were central A2-P2 scallop
pathologies. Recent experience has shown the ability to successfully treat pathologies outside of
these norms, which is discussed later in the chapter.
Fig. 15.2 (Top row) Bileaflet prolapse with severe mitral regurgitation. (Bottom row) Progressive degenerative
mitral valve disease with anterior leaflet prolapse and severe mitral regurgitation in a patient with prior annuloplasty ring.
15—PERCUTANEOUS EDGE-TO-EDGE MITRAL VALVE REPAIR USING THE MITRACLIP® 163
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MitraClip®
NT Device
(Clip)
MitraClip
NT System
Clip
Arm
Gripper
®
Steerable
Guide
Handle
Steerable Guide,
Steerable Sleeve,
and Delivery
Catheter
Clip Delivery System
Delivery
Catheter
Handle
Stabilizer
MitraClip
NT
Device (Clip)
®
AB
Fig. 15.3 MitraClip® NT system showing various parts of the clip and the delivery system. (Produced with
permission from Abbott Laboratories, Abbott Park, IL, USA.)
Procedural Details and Optimization
The MitraClip® (Fig. 15.3) is a transvenous transfemoral device implanted via a 24F steerable
guiding catheter (SGC) (tapers to 22F where it crosses the atrial septum) advanced into the left
atrium (LA) after a transseptal procedure. The SGC has an 80-cm working length with a
mounted 6 knob that allows for flexing (1) and straightening (2) of the catheter. The MitraClip® is a cobalt-chromium, polyester-covered device with movable arms. A fully open clip spans
20 mm, and at 120-degree grasping, it spans 17 mm. The newer XTR model has longer clip arms
(an additional 3 mm for each arm) and grippers with two additional rows of frictional elements.
It is advanced using the catheter delivery system (CDS) through the SGC into the LV, and the
MV leaflets are grasped between Nitinol grippers and the clip arms (see Fig. 15.3). The CDS has
a steerable sleeve (SS) and a delivery catheter (DC), which is used to advance or retract the clip
and to align it perpendicular to the MV coaptation plane. The CDS key material in the current
MitraClip® consists of nylon (instead of stainless steel in older iterations), allowing for improved
advancement and straddling.
TRANSSEPTAL PUNCTURE
The transseptal puncture is one of the most important aspects of the entire procedure. A good
transseptal puncture site for the MitraClip® is superior and posterior along the interatrial septum
that ensures an adequate height from the MV (Fig. 15.4). This is usually 4 to 4.5 cm for a prolaps-
ing leaflet and even higher for a flail leaflet. However, it is lower, around 3.5 to 4 cm, for the secondary MR cases, where the coaptation point is below the mitral annular plane. Likewise, the puncture
height might need to be adjusted for non–A2-P2 disease—higher for medial and lower for lateral
pathologies to allow for adequate space for catheter maneuvering and leaflet grasping. In some acute
cases of flail leaflets, the LA may not be enlarged, making it challenging to attain sufficient height
from the annular plane. The transseptal puncture usually needs to be extremely posterior to allow
sufficient distance from the annular plane. However, care must be taken during the puncture and
while advancing the guide and clip to avoid any LA perforation. A counterclockwise turn of the
sheath when advancing into the LA turns it anteriorly, away from the posterior wall/LA roof.
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Fig. 15.4 (A) X-plane transesophageal view of the interatrial septum with the transseptal needle tenting the
septum. (B) Four-chamber view showing the distance from the tenting point in the interatrial septum to the
mitral valve annulus (3.85 cm). (© 2018 Mayo)
MITRACLIP® PROCEDURE
After transseptal puncture, the transseptal sheath is advanced into the LA. An Amplatz wire is
then advanced into the left superior pulmonary vein through this sheath. Alternatively, a Torayguide (Toray) or ProTrack (Baylis Medical) wire can be looped in the LA. The transseptal sheath
is then exchanged out over this guidewire for the steerable MitraClip® guide catheter. The fluoroscopic bands at the end of the guide can also be visualized on TEE as having an echogenic
double-ring appearance. This allows for careful advancement of the guide catheter under both
fluoroscopic and TEE guidance (using short- and long-axis views to visualize the catheter tip),
thus avoiding injury to the LA free wall. The clip is then advanced through the guide using the
CDS, again under fluoroscopic and TEE guidance. For safe clip advancement, the initial direction of the guide catheter should be oriented posteriorly toward the left superior pulmonary vein
because this is the longest distance available in the LA. Once straddled in the LA, medial (M
knob) and slight posterior torque (clockwise rotation of SGC) along with retraction of the entire
system clears the pulmonary ridge and left atrial appendage, bringing the clip closer to the MV
(Video 15.1). Once the MitraClip® arms are opened above the MV, a 3D en face view on TEE
allows proper orientation of the clip arms (by rotating the DC handle clockwise or counterclockwise) perpendicular to the MV coaptation line (Fig. 15.5). Importantly, all manipulations and
A
Fig. 15.5 3D surgeon’s view of the mitral valve. (A) Orienting the clip arms in the left atrium perpendicular to
the mitral annular plane. (B) Double-orifice mitral valve after successful MitraClip®.
B
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Fig. 15.6 Leaflet grasping in the left ventricular outflow tract view.
positioning of the clip should be done in the LA above the MV leaflets. Once advanced into the
LV to grasp the leaflets, manipulations should be minimized to avoid chordal entrapment, which
can potentially worsen MR or result in cardiac injury requiring surgery.
14
The clip is then advanced into the LV using the DC handle in an open position (some operators might choose to advance in a semiclosed position, sometimes with a breath hold to avoid
rotation due to translation). Once in the LV, reexamine the clip carefully under TEE and fluoroscopy to ensure that no rotation of the clip has occurred, which might indicate interaction with
the chordal apparatus. The leaflets are usually grasped in the left ventricular outflow tract
(LVOT) view (Fig. 15.6). Once the leaflets are appropriately secured between the grippers and
clip arms, the arms are closed to plicate the anterior and posterior MV leaflets. An adequate tissue bridge should be confirmed after the grasp in multiple views, including 3D en face view (see
Fig. 15.5). Significant motion of any leaflet might indicate risk of leaflet escape from the clip and
need regrasping.
After release of the clip, the DC handle should be withdrawn carefully to avoid LA injury
from the exposed threaded fitting, again under TEE guidance while slowly releasing the M knob
and rotating the SGC anteriorly or posteriorly as needed. Additional clip placement should be
considered based on a comprehensive assessment of residual MR severity, MV gradient post-clip
(avoid if .5 mmHg), and reduction of LA pressure. In general, it is easier to deploy the second
clip lateral to the first one due to ease of maneuverability. Also, it is easier to deploy the second
clip toward the central A2-P2 segments. The second clip should be introduced into the LV in
either a closed position or not more than 60 degrees open to avoid interaction with the previous
clip. Operators should aim to place the second clip as close to the first as possible to achieve the
lowest-possible residual MV gradients. Fluoroscopy is useful in positioning the second clip and
avoiding contact with the first clip. Figs. 15.7 and 15.8 show a case of degenerative flail MV successfully treated with two MitraClips®.
In case the clip is not deployed due to technical reasons, extreme care should be taken to remove
the unused clip from the body. The clip arms should be fully closed, the DC handle should be fully
retracted, and the CDS knobs should be all neutral. Retract the CDS until it is 2 cm from the
SGC’s radiopaque tip ring, and adjust fluoroscopy for a side view of the SGC. Advance the DC
handle to expose about 4 cm of the DC shaft and withdraw the entire CDS as one unit. Rotate the
DC handle if necessary to ensure that both clip arms are seen en face on fluoroscopy. The SGC can
be straightened by moving the “6” toward “2” before retracting the clip into the SGC.
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BA
C
Fig. 15.7 Degenerative mitral valve disease with posterior leaflet flail (clockwise from first image). (A) Flail gap
in 2D TEE view. (B and C) Flail width in both 2D and 3D TEE views. (© 2018 Mayo.)
DEVICE STEERING
The MitraClip® system can be steered using either the SGC or the CDS. Moving the entire
SGC in or out will move the clip laterally or medially, respectively. Likewise, clockwise or counterclockwise rotation of the SGC moves the clip posteriorly or anteriorly. The “6” knob on the
SGC is commonly maintained in the neutral position in most cases unless necessary for advanced
maneuvers noted later. The CDS has “M” and “A/P” knobs, each controlling a cable that runs
through the length of the SS and interacts with the other. The “M” knob moves the clip medially
(with an aim to bring it perpendicular to the mitral annular plane) and anteriorly (the anterior
motion has been lessened in the newer versions). It is important to maintain optimal straddling
for optimal performance of these knobs. The “A/P” knobs are also primarily used in advanced
maneuvers discussed later.
1. Aorta hugger (anterior transseptal puncture): This can happen in case the needle slips or
passes through a patent foramen ovale. In case of anterior puncture, the best thing to do is
redo the transseptal puncture. If this is not an option, complex steering maneuvers are then
required; the “6” knob is turned to “1” to flex the SGC and “stand it up.” This maneuver
moves the clip posteriorly and must be corrected by anterior (counterclockwise) rotation
of the SGC.
2. Low transseptal puncture: An inferior or relatively anterior transseptal puncture will re-
sult in the clip being too close to the mitral annular plane. This might make retraction of
the clip into the LA, and thus arm orientation and even leaflet grasping, challenging. To
gain height, the SGC is rotated posteriorly (clockwise) to move it away from the mitral
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C
E
G
D
F
H
I
Fig. 15.8 MitraClip® procedure (moving in clockwise fashion from first image). (A) Posterosuperior transeptal
location. (B) Transseptal tenting measured from mitral valve annular plane. (C) Orienting the clip perpendicular to the mitral valve plane (in 3D). (D) Leaflet grasping in LVOT view. (E) Leaflet bridge confirmed on 3D after
first clip deployment. (F) Residual regurgitation on color Doppler after first clip. (G) Orienting the second clip
above the mitral valve medial to the first clip. (H) Final leaflet bridge after deployment of two clips. (I) Mild
residual mitral regurgitation after deployment of two clips. (© 2018 Mayo.)
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annular plane (Video 15.2). The “A/P” knob is then moved toward “A” to move the clip
back anteriorly, and any associated lateral movement of the clip is then corrected by using
the “M” knob.
3. High transseptal puncture: High transseptal punctures are rarely a problem, especially with
the newer-generation XTR clip with a longer working length of the CDS. However, to
lose height, one can rotate the SGC anteriorly (counterclockwise) while correcting it with
the “A/P” knob moved toward “P” (Video 15.3). Any associated medial movement of the
clip is then corrected either by sliding the whole system in or by releasing the “M” knob.
Postapproval commercialization of the device has been accompanied by broadening of the
restrictive EVEREST trial inclusion criteria (flail gap/width, baseline mitral valve area, etc.)
noted later. In fact, the Society of Thoracic Surgeons/American College of Cardiology (STS/
ACC) Transcatheter Valve Therapies (TVT) registry reported a baseline area of ,4 cm
2
in nearly
20% of patients. In a prospectively conducted study (n 5 51), Franzen et al. recruited a significant
proportion (69%) of patients outside the stringent EVEREST inclusion criteria.
15
These included patients with severe LV dysfunction (ejection fraction [EF] ,20%, left ventricular end
diastolic diameter .60 mm), smaller baseline mitral valve area (3 to 4 cm
2
in 11 patients), and
large flail gap/width. The authors achieved successful clip deployment in 96% of patients with a
low rate of periprocedural complications and reduction in MR grades in all treated patients. A
fully open first-generation clip spans 20 mm, and at 120-degree grasping, it spans 17 mm, making large flail gaps challenging. The newer MitraClip® XTR with longer arms is expected to
make grasping these larger flail gaps easier. Larger flail gaps have also been successfully treated
using rapid ventricular pacing or adenosine to induce ventricular standstill, thus reducing systolic
excursion of the mitral valve leaflets. The “zip and clip” methodology of placing the first clip
adjacent to the flail gap to approximate the mitral valve leaflets followed by another clip to close
the flail gap is an alternative. Patients with smaller baseline mitral valve areas might not be candidates for multiple clips using this methodology, due to the risk of causing stenosis of the valve.
Early trials recruited patients with primarily pathologies of the middle scallops (A2-P2) of
anterior and posterior mitral valve leaflets. Using a MitraClip® in non–A2-P2 regions is possible
but associated with relatively higher grades of residual MR in the TVT registry.
16
Commissural
MR originating close to the medial or lateral commissures is especially difficult to treat percutaneously due to the anatomic complexity of the underlying chordae and increased risk of entrapment. Hybrid techniques using an Amplatzer Vascular Plug (AVP) to close the relatively small
gap between the MitraClip® placed to the extreme lateral/medial side and the corresponding
commissure have been described (Fig. 15.9).
17
More data are needed regarding long-term stability of AVP devices in such cases and the potential risk of hemolysis due to creation of small residual orifices.
18
Although most commonly performed via transfemoral approach, alternative routes for Mitra-
Clip® have been described, including direct right atrial puncture
20
proach
via a right mini-thoracotomy. More recently, a case of transjugular approach was also
described.
21
The transjugular approach remains challenging due to the comparatively difficult
19
or a pulmonary venous ap-
transseptal puncture, which should be preferably done using a steerable sheath (Agilis NxT or
Baylis SupraCross steerable sheaths, etc.) (Fig. 15.10). From the limited data available, the transjugular approach might be suitable for central A2-P2 pathologies and especially difficult for
lateral pathologies due to difficulty in device maneuverability.
DEVICE IMPROVEMENTS
The classic MitraClip® device was updated to the MitraClip® NT version. The MitraClip® NT
delivery system handles and steers more smoothly due to replacement of stainless steel with
nylon, allowing for easier manipulation and positioning in the LA. There has also been a change
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