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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3795_Библиотеки_им_академика_М_И_Перельмана
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In: Perspectives in Aortic Valve Disease ISBN: 978-1-53618-769-4
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Editor: Giovanni Concistrè © 2020 Nova Science Publishers, Inc.
Chapter 19
AORTIC VALVE REPAIR
Stefano Mastrobuoni
and Gebrine El Khoury, MD
Cardiovascular and Thoracic Surgery Department, Saint-Luc’s Hospital,
Catholic University of Louvain, Brussels, Belgium
Aortic valve (AV) sparing and repair procedures are advantageous alternatives to
valve replacement in patients with aortic aneurysm with or without aortic regurgitation
but also for patient with isolated AV regurgitation without severe leaflet disease. A
successful repair strategy proceeds first from a clear understanding of the anatomy and
function of the AV and the potential mechanisms of valve dysfunction. The fundamental
starting point is the understanding that the AV is a functional unit composed of the valve
cusps and the functional aortic annulus. Lesion on any or more of these components can
induce aortic regurgitation as well as a gradient across the valve. A functional
classification of aortic regurgitation identifies 3 main mechanisms of AV regurgitation
although more than 1 type of lesion can coexist in any given patient. The goal of AV
repair is to improve the surface of coaptation by restoring the functional relation between
the leaflets and the FAA, while preserving the mobility of AV cusps. We present our
preferred surgical techniques for valve sparing-root replacement (VSRR) in the context
of tricuspid (TAV) and bicuspid (BAV) aortic valve. Further we will discuss our current
approach to isolated aortic valve regurgitation.
Keywords: aortic valve, repair techniques, sparing techniques
During the past 25 years, important advances in the field of aortic valve (AV) repair have
transformed it from an infrequent and anecdotal technique to a feasible and advantageous
, MD, Laurent De Kerchove, MD
ABSTRACT
INTRODUCTION
Corresponding Author’s Email: stm919@mail.harvard.edu.
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alternative to valve replacement in patients with ascending aorta aneurysm or aortic
regurgitation (AR). These advances included first a deeper understanding of the anatomy of
the AV and the mechanisms of AR; the development of surgical techniques aimed to restore
on the one hand the geometry of the aortic root while sparing the AV and on the other hand to
improve the leaflet coaptation while ensuring cusp mobility; and the development of a
common language that can be used by all clinicians to describe the lesions, discuss repair
techniques, and compare immediate and long-term results after repair.
Aortic regurgitation and aortic root aneurism concern mainly adolescent and young adults
with connective tissue disorders or other abnormal congenital valve diseases like bicuspid
aortic valve (BAV). In these patients, aortic valve sparing and repair procedures represent a
particularly interesting alternative to replacement because of the limitations of currently
available aortic valve substitutes. Although xenografts don’t need long-term anticoagulation
therapy, the high structural failure rate in young patients expose them to multiple rereplacements and increased morbidity and mortality . Mechanical valves have an excellent
freedom from reoperation, but a freedom from major bleeding and thromboembolic events of
around 90% at 10-year in young patients. Nonetheless recent studies showed very similar
long-term survival after AV replacement regardless of the type of prosthesis implanted. AV
replacement with the pulmonary autograft (the Ross operation) is ideal for young patients
with AV stenosis because of its durability, excellent survival, and low risk of thromboembolic
complications. However, the presence of aortic insufficiency and aortic root dilatation are
considered as important predictors of late pulmonary autograft failure .
This chapter attempts to describe the principles of correction of AV regurgitation by
focusing on functional anatomy and surgical techniques.
ANATOMY OF THE AORTIC VALVE
For the purpose of AV repair the AV should be considered as a functional unit composed
of two structures: 1- the functional aortic annulus (FAA) made by the Sino-Tubular junction
(STJ) and the Ventriculo-Aortic junction (VAJ) (Figure 1), 2- the valve cusps. The integrity
of these 2 components (the FAA and the cusps) is the basis for good valve function, and
dysfunction of one of them is frequently associated with dysfunction of the other as well.
Thus, a first fundamental principle in AV repair is that both lesions of the cusps and the FAA
should be addressed at the time of valve repair. Further, similarly to the annuloplasty during
mitral valve repair, dilatation of the VAJ should be addressed during AV repair even in the
absence of ascending or aortic root aneurysm.
The VAJ is the anatomical line of transition between the endocardium and the
endothelium and is a complex and non-planar structure (Figure 2). The aortic root inserts on
fibrous tissues in approximately one half of its circumference and on muscular tissues on the
other half. The fibrous portion, beneath the non-coronary cusp and half of the left coronary
cusp, consists in the aorto-mitral valve continuity and the two trigones. The muscular portion,
beneath the other half of left coronary cups and right coronary cusp, consists in the left
ventricular and interventricular myocardium. Beneath the right/non coronary commissure
stands the membranous septum and, below it, the bundle of Hiss. The basal ring is the virtual
plane passing through the nadir of the three cusps and is a surgical landmark. A clear
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comprehension of the relationship between the VAJ and the basal ring is of paramount
important for AV annuloplasty.
Figure 1. Anatomical specimen of the aortic root showing the position of the Ventriculo-aortic junction
(VAJ) (red line) and the Sino-tubular Junction (STJ) (blue line), in between, the three sinuses of
Valsalva and inter-leaflets triangles.
Figure 2. Anatomical specimen of a tricuspid aortic valve showing the fibrous (green arrowed line) and
the muscular portion (red arrowed line) of the VAJ (yellow dotted line). The membranous septum
(black dotted area) and the conduction bundles (red shadowed area) are also indicated. LCS: left
coronary sinus; RCS: right coronary sinus; NCS: non-coronary sinus. (Reprinted with permission).
Figure 3. Anatomical specimen of a tricuspid aortic valve showing the relation between the VAJ
(yellow line) and the basal ring (green line). At the level of the non-coronary and the left-coronary
sinuses the VAJ reaches the BR, but at the level of the right-coronary sinus the VAJ lays few
millimeters above the BR due to the presence of the muscular tissue of the inter-ventricular septum and
the right outflow tract. The picture shows also the mean distance observed between these two lines.
(Reprinted with permission).
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On its fibrous portion the VAJ is at the level of the basal ring while on its muscular
portion and at the level of the membranous septum the VAJ is a few millimeters higher than
the basal ring (Figure 3).
The diameter of the aorta at the level of the basal ring has a mean of 23±2mm in women
and 26±3mm in men without aortic root or valve disease and it is closely related to the body
surface area . In the context of chronic AR, oftentimes the VAJ and the basal ring are dilated,
particularly in patients with bicuspid AV (mean diameter of 27-28mm in TAV and 28-30mm
in BAV).
The distance between the lower point of the cusp insertion in the aortic wall and the
middle point on the free margin is the cusp height (also called geometric height) (Figure 4).
Figure 4. Anatomical specimen of a tricuspid aortic valve showing the geometric height (red arrowed
line): from the lowest point of the base of insertion of the cusp (black line) to the middle point on the
free margin (green dotted line).
The mean cusp height is 20mm in Tricuspid Aortic Valve (TAV) and 24mm in Bicuspid
Aortic Valve (BAV) (at the non-fused cusp) . A cusp height of 15mm or less in adult may be
considered as a sign of cusp retraction which in turn may reduce the cusps coaptation hence
causing regurgitation across the valve. Only part of each cusp joins the others during valve
closure. Indeed, on each cusp the coaptation surface area (mean of 1.25 cm²) corresponds
approximately to 40% of the total cusp surface. Therefore, the effective height is the distance
between the lower point of the cusp “belly” and the tip of coaptation in the center of the valve
(Figure 5). In competent AV, the effective height measures 9 to 10mm8. Moreover, the
effective height normally reaches approximately the mid-height of the commissures.
Nonetheless the length of coaptation varies along the cusp. The coaptation surface is indeed
bigger close to the commissures and smaller in the center of the valve.
The free margin of the cusp is on average 34mm long and is usually elongated in root or
ascending aorta dilatation involving the STJ as a compensatory mechanism11. Cusp prolapse
is nothing less than an elongated free margin.
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Figure 5. Diagram illustrating the use of the caliper in a tricuspid aortic valve to measure the effective
height of the cusp. The effective height corresponds to the height of the caliper hook when the convex
part sits perfectly on the cusp while the hook touches the free margin. eH: effective height, An: annulus
diameter.
FUNCTIONAL CLASSIFICATION OF AORTIC REGURGITATION
We have developed and implemented since many years a classification of the aortic
regurgitation that encompasses all the different causes of AR (Figure 6). This classification
aims to provide a common ground for surgeons, cardiologists, and cardiac echo specialists.
We further intended to point out the technique of choice for a specified mechanism.
Figure 6. Repair-oriented functional classification of Aortic Insufficiency with description of disease
mechanism and repair techniques used. FAA: Functional Aortic Annulus; STJ: sino-tubular junction;
SCA: sub-commissural annuloplasty. Reprinted with permission.
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Briefly, similar to the classic Carpentier’s classification of mitral valve regurgitation, in
the classification that we proposed, type 1 disease is caused by lesions of the FAA in the
setting of normal cusp motion, type 2 disease is caused by excessive cusp motion due to cusp
prolapse, and type 3 disease is caused by restrictive cusp disease. Nonetheless multiple
lesions can simultaneously contribute to AR, therefore correction of all contributing lesions is
critical for successful repair. Moreover, as in mitral valve regurgitation, severe chronic AR
can lead to dilatation of the ventricular-aortic junction. Therefore, also in patients with type 2
lesions (without aortic dilatation) annuloplasty of the VAJ should be considered particularly if
the VAJ is already enlarged. It is a matter of debate which is the cutoff for dilatation.
GENERAL PRINCIPLES OF AV REPAIR
The goal of AV repair is to restore an effective surface of coaptation by reestablishing the
functional relation between the leaflets and the FAA all the while preserving mobility of the
AV cusps. The mobility of the valve cusps depends on both the length of the free margin and
the length of the base of implantation. If increased cusp mobility may occur because of excess
free margin length (as in cusp prolapse) or over-reductive annuloplasty, a reduced mobility
may occur for dilatation of the VAJ (as frequently observed in bicuspid AV), overcorrection
of prolapse, and in cases of severe dilation of the STJ.
As aortic regurgitation can be isolated or associated with aortic root aneurysm, we will
discuss in the next sections the specific techniques of valve sparing – aortic root replacement
(VSRR) and of isolated cusp repair. Nevertheless, cusp repair is oftentimes required during
VSRR while aortic annuloplasty is required in isolated AR to stabilize the repair and ensure
durability. Further, the reimplantation of the valve during VSRR can elicit a cusp prolapse
that needs to be address for the good result of the operation. We will further discuss the
specific case of AV repair in cases of bicuspid AV.
AORTIC VALVE REPAIR IN TRICUSPID AV
Valve-Sparing Aortic Root Replacement with the Reimplantation Technique
The aortic valve sparing – aortic root replacement (VSRR) with the Reimplantation of the
aortic valve into a cylindrical Dacron graft has been introduced over two decades ago by Dr.
David and coll. as alternative option to composite replacement of the aortic valve and root
with a prosthesis (Bentall operation) in patients with aortic root aneurysm with or without
significant aortic insufficiency. VSRR-reimplantation is our technique of choice in cases of
root aneurysm with normal valve.
Compared to valve replacement with a prosthesis, VSRR allows a significant reduction of
prosthesis-related complications. However, the technical complexity of this procedure and the
concern for the durability of the re-implanted aortic valve have initially limited the wide
diffusion of this operation. Nowadays long-term results of this operation confirm the
excellent clinical results in terms of valve-related complications and survival, and the stability
of valve function over time with a low risk of recurrent aortic regurgitation or reoperation on
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the valve . Although severe calcifications or fibrosis determining valve stenosis or reduced
cusp mobility represent a contraindication to valve-sparing procedure, other cusp lesions such
as fenestration or prolapse should not deter to the use of this technique but they must be
addressed during the procedure in order to obtain a lasting result . Cusp plication to correct
prolapse has been applied in up to 60% of the patients with a tricuspid aortic valve
undergoing VSRR in our Institution15. Further, cusp prolapse can become evident after valve
reimplantation therefore a careful reassessment of the valve should be carried out before
termination of the procedure. Nonetheless, cusp prolapse can be easily corrected (as we will
see later on) and should not therefore preclude VSSR.
We have already and extensively described the technique of VSRR with reimplantation
that we have implemented and detailed videos are also available . Briefly, the procedure is
systematically carried out through a number of steps and allows no shortcut. The ascending
aorta is opened 1 cm above the sino-tubular junction and three traction stitches of 4-0
polypropylene are placed at the tip of each commissure. These stitches are extremely useful to
assess valve coaptation through all the steps and help expose the aortic root during external
dissection. A careful and thorough examination of the valve, aortic wall, coronary ostia and
VAJ is performed at this point and the decision to valve repair is eventually confirmed.
The first step of VSSR is the external dissection of the aortic root aimed to reach the level
of VAJ, given the constraints of the surrounding heart structures (Figure 7).
Figure 7. Intraoperative picture of VSRR in tricuspid AV showing the limits of external root dissection
in the area of the right ventricular outflow tract. The dissection should go beyond the VAJ (yellow line)
and reach the basal ring (green line) in order to have a horizontal suture line in this area. The pledgeted
stitches of the proximal suture have been already placed in the area of the left cusp.
The vascular graft should indeed necessarily sit at the level of the VAJ in order to both
realize a complete circumferential annuloplasty and avoid valve distortion during the
reimplantation. It is easier to start the root dissection along the Non-Coronary (NC) sinus
because there is not the constraint of the coronary arteries or other heart structures here. The
sinus of Valsalva is then resected leaving few millimeters of aortic rim towards the base of
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the cusp. Before the external dissection of the right and left sinuses, the coronary buttons are
isolated leaving a generous patch of aortic wall. Importantly, along the non-fibrous portions
of the annulus the external dissection of the aortic root should go as deep as the real level of
the VAJ, avoiding injuries to both the aortic root and the right ventricular outflow tract. The
external dissection is properly completed if the valve is completely free from the surrounding
structures and fully mobile at this point. After completion of the external dissection, the
stitches for the proximal suture line are passed horizontally through the VAJ. We usually use
ten to twelve 2-0 Tycron sutures with pledget that are distributed along the circumference of
the VAJ. The pledgets have to lay inside the left ventricular outflow tract (Figure 8).
Figure 8. Intra-operative picture showing the proximal suture line in VSRR-Reimplantation. Twelve
pledget stitches make a circumferential annuloplasty of the VAJ.
As we have seen before, attention must be paid to avoid the atrio-ventricular node and the
conduction tissue at the level of the R/NC inter-commissural triangle. The complete
annuloplasty realised by these pledget stitches prevent later dilatation and recurrence of aortic
regurgitation and is therefore a key-point for the success of valve repair10.
Figure 9. The height of the commissure between the left- and non-coronary cusps is the reference for
the choice of graft size. The height is measured from the base of inter-leaflets triangle corresponding to
the VAJ (thick purple line) to the tip of the commissure (thin purple line).
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The next step is the selection of the vascular graft that replaces the aortic root and where
the aortic valve will be re-implanted. The choice of a straight graft rather than a graft with
neo-sinuses is still matter of debate. Nonetheless we routinely use a graft with built-in neo-
aortic sinuses (GelweaveValsalva™ graft, Vascutek Ltd, a Terumo company, Renfrewshire,
Scotland) because we believe that this particular type of graft eases the procedure and may
have a clinical benefit on valve function. Our current graft-sizing technique has been
previously described. The size of the graft should be equal to the height of NC/LC
commissure measured from the base of inter-leaflets triangle to the top of the commissure
(Figure 9).
The stitches of the proximal suture line are then passed through the base of the prosthesis.
Finally, the graft is parachuted down and the stitches are tied to ensure appropriate seating
around the aortic annulus. It is important to avoid excessive tension on these stitches that may
otherwise tear the muscular tissue of the VAJ. Further, it should be recalled that this suture
line aims to fix the base of the prosthesis but it is the distal suture that ensure hemostasis.
During this step it is also extremely important to ensure that the stitches of the proximal
suture line have not caught the valve. The aortic valve can be now reimplanted into the graft.
The commissures are reimplanted first using 4-0 polypropylene sutures. To prevent valve
distortion, it is of paramount importance that the three commissures must be reattached at the
same level or eventually higher than the neo-sinotubular junction of the Valsalva graft. A
running suture starting from the commissure and aimed to fix the rest of the valve to the graft
is then performed in small regular steps. During this step, it is important to avoid a dead space
between the valve and the prosthesis that may cause bleeding. After valve reimplantation, it is
critical to re-examine the cusps for any residual prolapse, symmetry, and the height of
coaptation. A sealing test can also carried out to assess the competency of the valve. The last
step of the procedure will be the reimplantation of the coronary ostia. The left ostium, due to
its posterior position, is sutured first to the graft. We usually sew the coronary ostia with a
running suture of 5-0 polypropylene and a free autologous pericardial strip can also be used
on the coronary side to improve hemostasis. After the ostia are re-implanted, cardioplegia can
be given directly into the graft in order to distend the new aortic root, check for hemostasis
and also assess valve competence by indirect signs such as root pressure and left ventricular
dilatation. A further assessment of the valve is performed after cardioplegia. Cusp repair
should eventually be carried out at this moment.
Cusp Prolapse Repair in Tricuspid AV
Aortic regurgitation can be the result of isolated cusp disease. Grossly, cusp dysfunction
can be described as type-2 (cusp prolapse) or type-3 (cusp restriction) lesion according to our
classification (Figure 6). Type-2 dysfunction is the more common mechanism of isolated
regurgitation. In general, cusp prolapse is the result of an excess of length of the free margin.
Although cusp prolapse can exist isolated, it is commonly associated with dilatation of one or
more components of the FAA.
In the normal AV, the free cusps’ margins usually run parallel at the same level and join
each other in the center of the aortic root about 9-10mm above the nadir of the sinuses of
Valsalva (normal effective height). Cusp prolapse is then defined as one of these 2 situations:
1- when one (or more) of the free margins is lower compared to the others because of the
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excessive tissue and a transverse band can be present in the middle of the cusp body (Figure
10) (usually the transverse band can also be seen on echo imaging); 2- when the free margins
are the same level but their coaptation is lower than the normal reference (9 -10 mm of
effective height). In the latter situation the normal parallel configuration of the free margins is
respected but the entire coaptation is too low representing a risk of recurrent AI. Both type of
prolapse can occur after VSSR but the second type occurs when the commissures are not reimplanted high enough inside the graft or in case of severe free margin elongation as
observed in large root aneurysms.
Figure 10. Intra-operative picture illustrating a prolapse of the right coronary cusp (black arrow).
Compared to the left and non-coronary cusps, its free margin is lower and a transverse band is evident
in the body of the cusp.
Moreover, cusp prolapse may occur after VSRR if a too small graft has been chosen.
Consider indeed the exemplary case of a root aneurysm (>50mm) without significant
preoperative regurgitation. Reimplantation of this valve into a smaller graft (e.g., 28mm) can
be very likely associated to a relative excess of tissue and consequently cusp prolapse (Figure
11).
For tricuspid AV, prolapse of the RC or NC cusps is significantly more common than
prolapse of the LC cusp. In young patients prolapse is often associated with root dilatation
and connective tissue disorder.
Surgery for isolated AI starts with a transverse aortotomy 1cm above the sino-tubular
junction. The incision is extended circumferentially so that only the posterior 1-2cm of aortic
wall directly above the left coronary ostium is left intact. A traction suture is placed at the
apex of each of the 3 commissures to assess the valve mobility and the height of coaptation in
the arrested heart. Normally the cusps close at the level of the mid-height of Valsalva sinuses
with an effective height of 9-10mm. Effective height can be quantified also intra-operatively
by using a dedicated caliper . A cusp prolapse can be identified if the free margin is below the
reference point and lower than the other cusps. Once cusp prolapse is confirmed, the choice
of repair technique depends on the quality and quantity of cusp tissue. Central leaflet plication
and free margin resuspension are usually indicated in case of cusp of good quality with
flexible tissue. Triangular resection and pericardial patch repair are instead indicated in cases
of poor tissue quality with thickening, fibrosis or calcification.
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