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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3795_Библиотеки_им_академика_М_И_Перельмана-1
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Figure 1. Structural characteristics of sutureless Perceval S bioprosthesis (Reprinted
from Livanova website).
Figure 2. Perceval collapsed in delivery system (Reprinted from Livanova website).
Figure 3. Pre-implantation collapse and ballooning does not affect the structural integrity of the
collagen network of the pericardial cusp tissue (Reprinted from Livanova website).
Figure 4. Pericardial characteristic of Perceval prosthesis (Reprinted from Livanova website).
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This sutureless aortic valve prosthesis is available in size S, M, L, and XL. Perceval
obtained U.S. Food and Drug Administration (FDA) approval in January 2016. We instituted
oral anticoagulation therapy with warfarin sodium for 3 months after Perceval implantation
reaching an international normalized ratio between 2.0 and 3.0. After 3 months we
recommend, when there are no contraindications to suspension, the replacement of warfarin
with 100 mg daily of aspirin.
The use of sutureless bioprosthesis is contraindicated in case of acute endocarditis, pure
aortic regurgitation, irregular aortic annulus or ascending aorta geometry. The ratio between
the diameter of the sinotubular junction and the diameter of the superior annulus should not
exceed 1.3 (a ratio >1.3 can prevent a correct fixation of the valve-stent on the aorta). This
ratio was routinely determined with echocardiography and also with CT-scan in case of
isolated AVR. We performed in all patients undergoing isolated AVR CT-scan to planning
minimally invasive approach.
Implantation Technique
A higher aortotomy is required to accommodate the height of the cage and to allow for
closure of the aorta. We recommend a transverse aortotomy 3.5 cm above the annulus, or 0.5
cm above the sinotubular junction (STJ), approximating the epiaortic fat pad (Figure 5).
Commissural traction sutures for native valve exposure should be removed before Perceval
valve deployment because they distort the annulus. If the aortotomy is too low, care must be
taken to avoid catching the outflow ring during suture closure because this can displace the
valve and potentially cause intimal tears when the heart fills with blood.
Figure 5. High transverse aortotomy for Perceval implantation outlined in blue marking pen,
approximately 3.5 cm above annulus, and then after implantation.
Figure 6. Collapsing device (Reprinted from Livanova website).
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Figure 7. Perceval implantation.
This bioprosthesis can be collapsed through a dedicated device and positioned by means
of a delivery system (Figure 6).
Temporary guiding sutures are placed in the annulus at the nadir of each sinus and are
then passed though the eyelets of the valve (Figure 7).
During deployment, continuous traction is important to ensure that the valve is positioned
at the correct height. Because the non-coronary sinus is lower, the valve holder is tilted
toward the operator, thus aligning the valve with the left ventricular outflow tract (LVOT),
perpendicular to the annulus. Once the delivery system is in position, the prosthesis is
deployed, the guiding sutures are removed and the valve is finally in place; at this point a
post-dilation modeling is performed with a dedicated balloon (30 seconds at a pressure of 4
Atmosphere) and the valve flushed with warm saline at 37°C to optimize final sealing. The
operator visually confirms positioning, alignment, leaflet symmetry, coaptation, and patency
of the coronary ostia (Figure 7). Visible annulus above or below the valve indicates that the
height of deployment is incorrect. The commissures will be visible above the valve, but the
annulus should not appear. Forceps should be used to open the leaflets to confirm that the
annulus is not visible below the inflow ring. Circumferential examination of the prosthesistissue interface should detect PVL. This valve is retrievable and replaceable if necessary.
When a malposition occurs the Perceval valve can safely be removed even after balloon
dilation. The procedure performed is a ‘χ-movement’ with the aid of anatomical forceps. If
the prosthesis does not show any malformation after the procedure, it can be reimplanted in
the correct intra-annular position [2].
Sizing
Correct sizing requires particular attention. The transparent sizer must easily traverse the
annulus, whereas the white sizer must meet significant resistance or fail to pass (Figure 8).
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Figure 8. Sizing procedure.
Undersizing causes PVL secondary to inadequate annular sealing, central leak from
failure of central leaflet coaptation, or possible late proximal migration. Oversizing is a more
common mistake and it is discussed in the next paragraph.
Intraoperative transesophageal echocardiography assessment includes the same
parameters as those for evaluating a stented bioprosthesis. Additional evaluation is required,
focusing on correct intraannular position, thereby ensuring full cage expansion, appropriate
deployment height, presence of leaks, and leak significance. Short-axis views assess
deployment of the device (rule out infolding) and circumferential annular apposition.
Circumferential deformities warrant additional cross-clamping for visual evaluation,
particularly if they are associated with more than mild intravalvular regurgitation, PVL,
rocking, or high gradients. Normal Perceval leaflets may appear to open and coapt slightly
asymmetrically or display accentuated “leaflet fluttering” because they lack the rigid struts of
a typical stented valve. In isolation, these findings are of no concern. Central regurgitation
occasionally accompanies the asymmetric coaptation. It should be no greater than mild in
severity and typically resolves over time. Long-axis views assess angulation of the valve and
aortic root parameters. Although an angulated conventional stented prosthesis does not
always entail poor valve implantation, it should raise more concern with the Perceval valve.
Visible edges of the device should line up with the virtual parallel lines formed by the LVOT,
aortic root, and ascending aorta. The cage should also conform to the aortic root and engage
the STJ. The proximal inflow ring will extend below the native valve annulus. If the valve is
deployed at the appropriate height, the location of the Perceval and native valves’ hinge
points should match (within 1 to 2 mm). The known dimensions of the Perceval valve can
locate a “virtual hinge point” when shadowing occurs. Create a reference point using
distances from the anterior mitral leaflet and STJ to the native hinge point and compare with
the virtual hinge point described earlier. Observation of inflow ring impedance of anterior
mitral leaflet opening may suggest low deployment, as well as membranous septum
compression and risk of atrioventricular conduction block. After valve deployment, isolated
trace PVL is rarely concerning. Eccentric PVLs make grading challenging, and jets splaying
across the LVOT can be overestimated. Generally, any PVL greater than trace or the presence
of multiple jets warrants repeat visual inspection of the valve and potentially further annulus
debridement and valve redeployment.
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Role of Oversizing
Excessive oversizing of the Perceval valve is associated with increased transprosthetic
gradients and should be avoided. Grossly oversized Perceval bioprostheses tend to recoil,
causing loss of contact between the prosthesis and the annulus, which results in paravalvular
leakage and, possibly, in significant aortic regurgitation. Recoiling has been observed in the
clinical setting and in the laboratory [3, 4]. An oversizing of 30% or more in the annular
cross-sectional area was associated with a 16-fold increase of the risk of developing increased
postoperative gradients [5]. In our experience some typical predictors of prosthesis-patient
mismatch, such as the patients’ body surface area and the size of the implanted prosthesis,
were not related to the outcome, whereas a greater degree of oversizing was associated with
increased gradients. This apparent paradox is, in our opinion, well explained by the fact that
the full expansion of the valved stent inside the patient aortic annulus could be associated
with smoother leaflet kinetics, improved valve opening, and increased effective orifice area
(EOA), whereas the stent compression or deformation that follows the implantation of a
prosthesis that is too big with respect to the patient annulus could lead to altered kinetics of
the leaflets, incomplete valve opening, and increased gradients. In fact, the Perceval valve has
an in vitro EOA that is much higher than that of conventional sutured bioprostheses [6, 7]: the
in vitro EOA for the S size ranges from 2.07 to 2.2 cm2 [6], and in a study of patients with
small annuli, the measured in vivo EOA index was 1.12 ` 0.2 cm2/m2 vs 0.82 ` 0.1 cm2/m2
for small size conventional, sutured valves [8], indicating that the fluid dynamics of valved
stents might be superior to those of conventional surgical valves. The observation that the use
of transcatheter aortic valves is associated with a higher EOA index and with a reduced
incidence of prosthesis-patient mismatch would also support this idea [8]. A secondary
finding of our experience is that intraoperative sizing for the Perceval valve, as recommended
by the instructions for use, does not reflect the true in vivo measure of the aortic annulus and
could be misleading. Surgical obturator-based sizing is a complex process that converts to a
number several nonnumeric inputs, including visual assessment, tactile feedback, stiffness of
the cardiac tissues, the amount and distribution of calcium, the fragility of the aortic wall or
the height of the coronary arteries, and others. Furthermore, the surgical sizers and the sizing
strategy both differ significantly between different prostheses, making the sizing process even
more complex [9]. In our experience, there was an impressive degree of overlapping between
the four prosthetic sizes. Surgical sizing resulted in a mean oversizing of more than 20% and
probably led to the implantation of a too big prosthesis in a significant proportion of patients.
Other authors have reported difficulties with the Perceval sutureless sizing process. Baert and
coworkers [4] recently reported valve recoiling caused by excessive oversizing in 4 patients
(2.9% of their Perceval population). They suggested to modify the sizing process and to
implant the valve size “Given by the sizer of which the white obturator pass the annulus with
friction” [4]. This would certainly reduce the number of grossly oversized prostheses but that
the choice between different valve sizes in patients with similar annular dimensions would
remain arbitrary. In our opinion, cardiac CT could offer a simple solution to this problem. In
fact, cardiac CT has become a very standardized process and is used with an extremely high
rate of success in thousands of TAVI patients every year. Given the surprising forgivingness
of the Perceval valve, the development of a CT-based sizing reference chart would not be
complex: the valve showed good hemodynamic performance in a wide range of conditions
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and still behaved acceptably in the extreme conditions of virtually no to almost 50%
oversizing (Figure 9).
Figure 9. Double oblique axial computed tomography images of the virtual basal ring (VBR) from 6
patients. (Upper row) Three patients with virtually identical aortic annular sizes (3.7 cm2) who received
3 different prosthesis sizes (small [S], medium [M], and large [L], respectively). The ex vivo area of the
implanted prostheses is represented with 3 closed circles for comparison. (Middle row) Three patients
with virtually identical aortic annular sizes (4.1 cm2) who received 3 different prosthesis sizes (S, M,
and L, respectively). (Bottom row) The VBR area of this patient (4.14 cm2, center) is depicted against
the ex vivo area of the S, M and L Perceval (LivaNova, Saluggia, Italy) valve (left). The patient
received an M valve. The postimplant area of the VBR was 4.18 cm2, indicating minimal expansion of
the aortic annulus after the implantation. The patient underwent valve-in-valve implantation with
a 23-mm Sapien 3 valve (Edwards Lifesciences, Irvine, CA) for valve failure 3 years after
the original operation.
Results
First clinical results of Perceval bioprosthesis were reported in 2011 by the group of
Flameng and colleagues [10]. A larger multicentre experience with Perceval aortic
bioprosthesis was reported by Shrestha et al. [11]. Fischlein et al. reported low 1-year event
rates in intermediate-risk patients undergoing AVR from a large multicentre cohort study
[12]. In our experience up to 2015, 30-day mortality was 1.9% (12/617) and survival was
91.3% at follow-up. Relative to others series, we found similar results in terms of
paravalvular leakage and hemodynamic performance. Specifically, we found 3 patients with
moderate paravalvular leakage without hemolysis not requiring any treatment. Two patients
had incomplete expansion of Perceval valve due to oversizing of bioprosthesis, caused early
moderate paravalvular leakage, required reoperations at 2 and 9 postoperative days. The
Perceval bioprosthesis selected for implant should match the measured diameter of the aortic
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annulus. Margaryan et al. analyzed 54 patients underwent Perceval who had preoperative
contrast-enhanced multidetector-row computed tomography (MDCT). Echocardiographic
measurements showed lower accuracy compared to MDCT measurements. They concluded
that possibly for precise aortic annulus measurement, contrast-enhanced MDCT is preferable
[13]. According to the 2-year follow-up of the PARTNER trial, paravalvular leakage was
more frequent in patients undergoing transcatheter aortic valve implantation (TAVI) and this
was associated with increased risk of mid-term mortality, even in those with mild leakage
[14]. In our single center series, paravalvular leakage occurred at follow-up in 36 patients, of
whom 3 had moderate paravalvular leakage. Although the reduced time needed for
implantation is a theoretic potential advantage of this prosthesis, in our experience mean CPB
and ACC time were longer than other studies [10-12]. This might certainly be related to
surgical approach. In 475 (77%) patients Perceval was implanted in minimally invasive
approach. A meta-analytical study showed CPB time of 104.4 minutes for minimal access
group underwent AVR versus 94.0 minutes for conventional access group (p < 0.00001) [15].
Our experience showed CPB time of 81.7 minutes for minimal access group underwent AVR
with Perceval valve. As minimally invasive AVR has shown longer CPB and ACC time than
conventional surgery, we strongly believe that sutureless technology might be the solution for
less invasive approaches. In our experience ACC and CPB times of minimally invasive AVR
with conventional sutured bioprosthesis were 87 and 121 minutes versus 50.5 and 81.7 with
Perceval bioprosthesis. The advantages of Perceval implantation in ministernotomy approach
have been described by Fischlein et al. with good results [16]. On the other hand, we reported
AVR through a right minithoracotomy, which avoids opening the sternum, but requires
greater technical skills, and may be a challenging and long procedure even for expert
surgeons. The potential advantages of the right minithoracotomy for AVR as well as the
potential limitations and drawbacks of this technique have been recently reviewed [17].
Especially when the ribs are not resected or disconnected from the sternum, this procedure
may be very challenging because of the limited field and the difficult exposure of some
regions of the aortic annulus, this reflected by the longer operative and cross-clamp times
reported with this approach. The sutureless prostheses might represent a solution to this
problem. Semsroth et al. compared patients underwent AVR with sutured prosthesis through
an anterolateral minithoracotomy versus partial upper hemisternotomy. In this study a median
cross-clamp time of minithoracotomy group was 93 minutes and a median perfusion time was
137 minutes [18]. In our series, patients underwent AVR with sutureless Perceval
bioprosthesis presented a mean cross-clamp time of 52 minutes and a mean perfusion time of
82.3 minutes. Besides the possible facilitation of minimally invasive approach, this prosthesis
may also be advantageous for patients needing AVR replacement long with concomitant
procedures that prolong CPB and ACC times. In our experience, there were a significant
number of patients who had concomitant mitral surgery. The procedures on the mitral valve
are always mitral anuloplasty with incomplete ring implantation. Incomplete mitral ring
prosthesis allows correct implantation of sutureless bioprosthesis. In concomitant mitral
surgery, we performed before mitral anuloplasty and after the Perceval implantation to avoid
dislocation of bioprosthesis during the mitral surgery. Mean transvalvular gradient at midterm follow-up was 11.9 ± 5.4 mmHg. Left ventricular mass decreased from 146.57 g/m2
before surgery to 112.6 g/m2 at follow-up (P < 0.001). In our experience the rate of
perioperative pacemaker implantation was 5% (30/617). This result is lower than the largest
European multicentre experience [19]. Until 2020, we have implanted more than thousand
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Perceval in our Center. Vogt et al. identified preoperative presence of right bundle branch
block (RBBB) as independent predictors of postoperative conduction disorder [20]. The rate
of preoperative RBBB was lower than the study of Vogt (3.6% vs. 7.8%). This could be the
reason why the rate of pacemaker implantation is lower in our experience than the other
studies. In TRASFORM clinical trial, the rate of permanent pacemaker implantation for the
Edwards Intuity was 11.9% [21].
RAPID DEPLOYMENT INTUITY ELITE VALVE
INTUITY Platform Technology
Starting from 2012 the first-generation of Intuity Valve System (model 8300A; Edwards
Lifesciences) was available for surgical AVR. The Edwards Intuity valve system consist is a
stented trileaflet bovine pericardial bioprosthesis with a balloon-expandable, cloth-covered
stent frame at the inflow aspect and combines the long-term safety and efficacy in terms of
hemodynamics results of bioprosthesis Carpentier Edwards Perimount with the simplicity and
quickness on implantation of transcatheter valve prosthesis. The pericardial stented aortic
valve is based on the design and the proven performance of the PERIMOUNT valve family.
A balloon expandable stainless steel cloth-covered frame is incorporated into the inflow
aspect of the valve. The valve is implanted with the aid of a delivery system, which
incorporates a balloon catheter to expand the frame within the left ventricular outflow tract
(LVOT). The expandable frame works in conjunction with the sewing ring to position and
stabilize the valve at implant. The system reduces the number of sutures required to secure the
valve, while the frame establishes a seal within the LVOT. These new valves are so termed
“rapid-deployment valves” because their implantation (rapid-deployment aortic valve
replacement [RDAVR]) requires only 3 sutures. Another design improvement of these
bioprosthesis is a shaped skirt along the underside of the valve; the skirt acts to mechanically
maintain effective orifice area (EOA) in aortic placement and to provide a substrate for
fixation and an associated significantly reduced need for suturing. The second generation
Intuity Valve System (model 8300AB; Edwards Lifesciences), named INTUITY-Elite® valve
(Edwards Lifesciences, Irvine, CA, USA) received CE Mark European approval in April
2014 and presents three minor design modifications made to enhance seating during
implantation. First, the number of cloth layers on the frame was reduced and the cloth was
shifted down closer to the inflow edge of the annulus frame. With the cloth on the annulus
frame moved down, the resulting tissue annulus diameter was reduced by 1 mm. Second, the
single, crimped cloth-covered, expandable stainless steel frame was double crimped to further
reduce the implant profile. Third, the valve holder is now cusp-mounted instead of
commissural-mounted to increase the visibility for the nadir suture markers.
The model 8300AB is a stented trileaflet valve comprised of bovine pericardium treated
with the Carpentier-Edwards ThermaFix process. The leaflets are mounted on a flexible
cobalt-chromium alloy wireform. The inflow of the valve incorporates the cloth-covered
balloon expandable frame. The EDWARDS INTUITY Elite valve system is available in sizes
19, 21, 23, 25, and 27 mm (Table 1).
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Table 1. Nominal dimensions (mm) EDWARDS INTUITY Elite Valve
Reprinted from accessdata.fda.gov
Figure 10. Edwards INTUITY Valve System Elite - Valve Technology and Delivery System. Reprinted
from Edwards website.
The valve is packaged and terminally sterilized in glutaraldehyde. Glutaraldehyde is
shown to both reduce the antigenicity of tissue xenograft valves and increase tissue stability.
The wireform is made of cobalt-chromium alloy. The wireform is covered with a knitted
polyester fabric. A thin, cobalt-chromium alloy/polyester film laminate band surrounds the
base of the wireform. A silicone sewing ring which is covered with a porous, seamless
polytetrafluoroethylene (PTFE) cloth is attached to the wireform. The scalloped sewing ring
is designed to conform to the native aortic annulus. The compliant nature of the sewing ring
facilitates coaptation between the valve and an often irregular or calcific tissue bed. The
sewing ring has three suture markers to aid in valve orientation. A holder is attached to the
valve by means of sutures to facilitate handling, deployment, and suturing the valve during
the implant procedure. The holder is easily detached by the surgeon. The delivery system
includes an integrated balloon catheter and malleable tubular handle shaft through which the
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catheter extends. The distal end of the handle shaft includes an adapter, which mates with the
holder of the valve, and a locking sleeve for rapidly connecting the delivery system to the
valve holder. The balloon portion of the delivery system resides within the adapter, and
advances distally into position for expanding the frame. A tubular balloon introducer is
attached, when removing the valve from a storage jar, and facilitates passage of the balloon
through the valve. The malleable handle is made of aluminum and has chromate conversion
coating applied over the entire surface of the part. The inflation device is used to pressurize
and expand the balloon (Figure 10).
The Edwards Intuity Valve is indicated for the replacement of the diseased, damaged or
malfunctioning native or prosthetic aortic valves. The use of this valve system is
contraindicated in case of pure aortic regurgitation and in patients with aneurysms of the
aortic root or ascending aorta.
Implantation Technique
A standard CPB is established. Most important is the incision of aorta that will allow for
coaxial delivery of the Intuity valve; proper angulation of the delivery device is critical to
seating the valve perpendicular to the annulus. While a transverse aortotomy may be
sufficient in patients with dilated ascending aorta, the aortotomy in patients with normal
diameter of ascending aorta should be directed to the non-coronary sinus and extended past
the sinotubular junction (STJ) [22], especially in patients with narrow supracoronary aorta
(Figure 11).
The native aortic valve leaflets are excised and a total decalcification of the annulus is
performed. Debridement of the calcium from the annulus, left ventricular outflow tract
(LVOT), and the anterior mitral valve leaflet must be performed beacause the inside of the
annulus and LVOT should be smooth to ensure proper seating of the prosthetic valve to
achieve a good seal and minimize the risk of paravalvular leaks. Otherwise an excessive
debridement may result in annular injury or creates divots, compromise the integrity of the
aortic annulus, and it must to be avoided and/or results in paravalvular leak. Three equidistant
guiding sutures are placed through the nadir of the aortic annulus and then placed in
corresponding positions through the sewing ring of the valve. A simple suture technique is
recommended to help confirm seating of the valve. The pledgeted sutures or monofilament
sutures are not recommended. The use of pledgets may create leak channels resulting in
paravalvular leaks. The use of monofilament sutures and resulting suture tails may damage
the leaflets. Simple suture technique is recommended with suture entering just below the
annulus and exiting 2-3 mm above the annulus. A suture entry site too low, in order to avoid
deep-seating the valve, may lead to conduction disturbance. The exit site should be high
enough on the aorta to visualize around the sewing cuff of the seated valve (Figure 12). If one
of the sinuses appears relatively large and prolapsed, two sutures can be placed within that
sinus to bring the tissue in plane with the valve.
By using the guiding sutures, the valve and attached delivery system are lowered onto the
annulus and secured into position under direct vision. It should also be confirmed that any
atherosclerotic plaque be debrided from the aortic root and STJ. During parachuting must be
maintained counter traction on the sutures. It is importantant to avoid bending the malleable
handle greater than 90 degrees and more than three times. Once seated, we must hold the
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