Aortic Valve Repair
Keywords: Aortic Valve Repair, Operations for Valvular Heart Disease, aortic
valve Repair, aortic valve surgery, cardiac surgery
Aortic valve repair has been shown to yield good outcomes
for select patients when performed by trained surgeons. In this chapter, we
will discuss the surgical anatomy of the aortic valve, the surgical steps to
aortic valve repair, as well as the pre-, intra-, and postoperative
considerations that need to be addressed for a successful repair.
 |
Figure 12.1 (A) Aortic valve anatomy. (B) Ventriculoatrial
junction.
·
Aortic valve repair (AVr) has been
shown to have a lower rate of valve-related complications compared to aortic
valve replacement (AVR).1-3
· It is especially beneficial for
those in the younger age group due to a higher rate of bioprosthetic
degeneration in the case of AVR and the cumulative risk of thromboembolism and
bleeding in mechanical aortic valves.3
Step 2. Surgical Anatomy
·
The aortic valve (AV) is comprised
of the functional aortic annulus and cusps.
· The functional aortic annulus is
comprised of the sinotubular junction (STJ) and ventriculoaortic junction
(VAJ4,5; Fig. 12.1).
·
The basal ring is the plane that
passes through the nadir of the aortic cusps.
·
At the right noncoronary
commissure, the membranous septum is the border of dissection for the VAJ. At
the left-right coronary commissure, the ventricular muscle is the border for
VAJ dissection. These anatomic borders illustrate why the VAJ does not reach
the basal ring.
· The VAJ level approximates the
basal ring level at the noncoronary sinus (NCS), noncoronary left commissure,
and left coronary sinus (LCS).
· The aortic cusp geometric height
is the maximum tissue height. The effective height measures from the basal ring
plane to the level of the central coaptation of the cusps (Fig. 12.2). The
noncoronary cusp (NCC) is higher than the right coronary cusp (RCC) and left
coronary cusp (LCC).4,6
· The AV cusp coaptation normally
occurs at the midlevel, between the STJ and VAJ.4,7,8 Effective cusp coaptation
length is 2 to 6 mm.4,7
· Cusp mobility is a function of the
free margin length in relation to the length of annular cusp insertion.4
These lengths are adjusted appropriately during a repair to reestablish valve
competency while ensuring good mobility.
· Alteration in one component of the
AV leads to alteration in the others. Each component should be seen in relation
to the others.
· A repair-oriented classification
of aortic insufficiency (AI) has been developed to guide patient selection and
treatment3 (Fig. 12.3).
· Various forms of cusp division and
fusion can occur, resulting in unicuspid, bicuspid, and quadricuspid anomalies,
which may be associated with aortopathy and congenital cardiac diseases.
· The most common cause of AI is
dilation of the functional aortic annulus. Thus, a focused history on the
presence of hypertension, family aortic and connective tissue disorders, and
the acuity of signs and symptoms will help with management. A history of
infective endocarditis, or rheumatic heart disease or the presence of
myxomatous mitral disease may infrequently be associated.
·
Preoperative echocardiography
(echo) is essential for identifying the cause of the AI and will help guide the
intraoperative evaluation. It should be able to demonstrate the aortic root and
ascending aorta dimensions. The echocardiogram will also be able to show the
anatomy of the cusps and the presence of prolapse, fenestrations, bands,
calcifications, and vegetations. The quality and direction of the AI jet should
also be examined.
 |
Figure 12.2 The coaptation height and length and geometric height of the AV
leaflets.
Figure 12.3 Functional classification of aortic valve insufficiency.
|
·
Cusp prolapse occurs when one or
more cusps coapt below the normal height of coaptation, at the midheight of the
sinus of Valsalva. The presence of an eccentric jet is a sensitive indicator of
prolapse. The presence of a fibrous band is a very specific sign of cusp
prolapse and identifies the prolapsing cusp8 (Fig. 12.4).
· In patients in whom the aortic
dimensions are borderline, a preoperative chest computed tomography (CT) scan
will aid in a more definitive measurement of the dimensions.
· A transverse aortotomy is
performed, 1 cm from the STJ, leaving 2 to 3 cm of posterior aorta intact. The
distal aorta is retracted cephalad for a better exposure of the AV; 4-0
polypropylene sutures are placed at the level of each commissure (Fig. 12.5).
· Axial traction (perpendicular to
the annular plane) is placed on the commissural retraction sutures to assess
the AV. The AV anatomy is thoroughly examined, including the cusp coaptation,
amount of excess tissue, leaflet mobility, presence of restrictions and
calcifications, and bands. The characteristic of the aortic sinuses are
likewise examined for suggestions of aneurysmal degeneration such as wall
thinning and coronary ostia displacement (Video 12.1).
· A prolapsing cusp can be
identified by the presence of excess free margin length and, occasionally, a
transverse fibrous band.
· Radial traction (parallel to the
annular plane) is then applied to the commissural stitches, and the center of
the cusp free margin is pushed gently to the left ventricle. A nonprolapsing
cusp will remain at the physiologic level, which is halfway between the cusp
base and its maximal height at the commissure. A prolapsing cusp will be able
to be pushed lower into the left ventricle due to excessive amounts of tissue.
· Cusp repair is then performed
using free margin plication or resuspension or both. Annular stabilization can
be performed with a subcommissural annuloplasty (SCA) or external or internal
ring.
 |
Figure 12.4
Transeosphageal echocardiographic images.
(A) Eccentric aortic insufficiency jet. (B) Cusp prolapse and fibrous band (white
arrow). (C) Fibrous band (white arrow). (D)
Fibrous band (black arrow).
Figure 12.5 Aortic valve exposure using axial traction.
|
· A 7-0 polypropylene suture is
passed through the center of the two nonprolapsing cusps which will serve as
reference. Gentle axial traction is applied to the reference cusps, and the
prolapsing cusp is pulled parallel to the reference cusp. A 6-0 polypropylene
suture is passed through the prolapsing cusp from the aortic to the ventricular
side, where it meets the center of the reference cusp. The direction of
traction is then reversed, and the same suture is passed from the ventricular
to the aortic side at the point where it meets the middle of the reference
cusp. This excess free margin is then plicated by tying the suture with the
excess tissue on the aortic side. Further plication is done until it is 5 to 10
mm onto the body of the aortic cusp, using interrupted or running locked 6-0
polypropylene sutures. Significant excessive tissue may be resected before the
plication (Fig. 12.6; Video 12.2).
· In the case of two prolapsing
cusps, a 6-0 suture is passed through the center of the free margin of the
reference nonprolapsing cusp. One prolapsed cusp is then pulled parallel to the
reference cusp, and a 6-0 suture is passed through the free margin at the point
where it meets the center of the reference cusp. Then the suture is passed back
through the cusp at an equivalent distance from that cusp’s center, toward the
other side. Plication then proceeds as above and is repeated for the second
prolapsing cusp.
·
In the case of all three cusps
prolapsing, careful surgical art and judgment are applied, with the goal of
plicating the free margins enough so that the cusps coapt at the midpoint level
of the aortic sinuses.
 |
Figure 12.6 Cusp repair: central margin
plication. (A) A polypropylene 7-0 suture is passed through the center of the
two nonprolapsing reference cusps and gental
axial traction is applied. The prolapsing cusp is then pulled parallel to the
reference cusp and a polypropylene 6-0 suture is passed through
the prolapsing cusp, from the aortic to the ventricular side, at the point
where it meets the center of the reference cusp. (B) The
direction of the traction is reversed, and the same suture is passed from the
ventricular to the aortic side of the cups where it meets the middle
of the reference cusp. (C) The excess free margin which is now delineated is
plicated by tying the suture, leaving the excess tissue on
the aortic side. (D) The plication is extended 5-10 mm onto the body of the
cusp by additional interrupted or running locked polypropylene 6-0
sutures.
|
·
Resuspension of the free margin
allows symmetric shortening and reinforcement, which is particularly useful if
there are cusp stress fenestrations. A 7-0 polytetrafluoroethylene suture is
passed through the free margin, 0.5 to 1 mm from the edge. A second suture is
passed 1 to 1.5 mm below the first, going beyond the fenestration if there is
one.12 When appropriate correction has been reached, the two sutures are tied
at the opposite ends (Fig. 12.7).
·
Decalcification is done to
optimize leaflet mobility. A no. 11 blade is used to shave off the calcium
through a plane in the leaflet, taking care to avoid perforation. Excessive
calcification, restriction, and fibrosis do not result in a good valve repair
and is an indication to proceed with valve replacement.
·
Type III lesions with limited
calcification and fibrosis may be amenable for repair through decalcification,
resection, and patching. Cusp perforations may also be repaired with a patch. A
pericardial patch is trimmed to resemble the defect in shape, with an
additional 2-mm margin around it. This is secured to the aortic surface of the
cusp using a continuous Prolene 5-0 or 6-0 suture. As yet, there is no proven
benefit for the use of one type of patch material or another. Nontreated
autologous pericardium is preferred for simple repair and bovine pericardium
for complex repair.13 AV repairs necessitating a patch are at higher
risk of failure, possibly due to the progression of the inherent disease of the
leaflet, as well as deterioration of the patch material (Fig. 12.8).
 |
Figure 12.7 Cusp repair: resuspension of
the free margin. (A) A polypropylene 7-0 suture is passed through the center of
the two nonprolapsing reference cusps and gentle axial
traction is applied. (B) A Gore-Tex 7-0 suture is passed twice on the top of
the commissures of the prolapsing cusp. (C)
One arm of each of the sutures are then passed using a running technique over
and through the length of the free margin. (D) Using gentle
traction on the sutures and an opposite traction on the middle of the free
margin, the first half of the free margin is shortened by
wrinkling the tissue until it reaches the same length as the adjacent reference
cusp. (E) Wrinkling is then done on the second half using the same
technique, allowing symmetric shortening. (F) The suture ends are passed
through the aortic wall and tied.
Figure 12.8 Pericardial patching using
autologous or bovine pericardial patch.
|
· Annular stabilization improves the
durability of AV repair by stabilizing and reducing the diameter of the VAJ and
STJ, thereby increasing cusp coaptation. The most durable is the
prosthesis-based annuloplasty that is part of a valve-sparing root replacement
(see the following).
·
SCA is simple and reproducible. It
is done using pledgeted braided sutures, with the first arm passed from the
aortic to the ventricular side, into the interleaflet triangle, and coming out
on the other side of the commissure on the same level as the entry point. The
second arm of the suture is passed in a similar fashion, just below the first.
The opposite pledget is placed, and the suture is tied. This is done for all
the interleaflet triangles. The annuloplasty effect is greater if the SCA
sutures are placed closer to the VAJ. Typically, SCA sutures are placed between
the upper and middle thirds of the height of the interleaflet triangle (Fig.
12.9; Video 12.3).
· The use of basal rings, both
external and internal, is still under study. External rings are flexible
circumferential bands implanted around the lowest outer portion of the aortic
root, with the interrupted sutures passed from inside the root, 1 to 2 mm below
the cusp. Internal rings are implanted 1 to 2 mm below the cusps, with the
sutures tied externally at the base of the aortic root.
·
Although annular stabilization
provides durability to the AV repair, care should be taken to avoid
overreduction, which could lead to aortic stenosis but may also cause cusp
prolapse and AI. Internal rings also have a theoretical increased risk for
thromboembolic events.
 |
Figure 12.9 Subcommisural annuloplasty. (A)
Passing the sutures from one sinus to the other. (B) Illustration of the
placement of the pledgeted sutures in relation
to the interleaflet triangle.
·
The aorta is transected 1 cm from
the STJ. An initial assessment of the aortic root and valve cusps are done (as
described previously) to assess for the viability of repairing the valve and of
preserving or replacing the root. In the case of borderline clinical
indications for aortic root aneurysm, the presence of thinned-out aortic
sinuses and displacement of one or both coronary ostium guides us to performing
a root replacement. If the AV is deemed reparable, the aortic root replacement
is first performed through a reimplantation or remodeling technique.
· Graft sizing is critical to
achieve correct alignment of the AV structures. One method is to apply adequate
radial and axial traction on the commissural sutures to re-create the most
competent valve configuration and then measuring the STJ in this position using
a Hegar dilator or Freestyle valve sizer (Medtronic, Minneapolis; Fig. 12.10).
Another simple but effective method is by measuring the height of the
interleaflet triangle at the NCC-LCC commissure. This height would approximate
the VAJ diameter, STJ diameter, and graft size of a Valsalva graft (Vascutek
Ltd, Renfrewshire, Scotland, UK). In case of noncorrespondence of graft size,
one size above is chosen15 (Fig. 12.11A–D). The Valsalva graft is
then patterned according to the height of the two other commissures (see Fig.
12.11E).
 |
| Figure 12.10 Graft sizing using a Freestyle valve sizer. |
· After the proximal aortic root
anastomosis and implantation of the coronary buttons, cardioplegia is applied
through the graft for myocardial protection as well as to check for hemostasis.
During this time, a limited transesophageal echocardiography (TEE) may be
performed to check the AV function after the root replacement. The cardioplegia
fluid is then carefully suctioned, taking care not to disturb the cusp
positions. This postcardioplegia position is the most physiologic evaluation
available for the AV on an arrested heart. The cusps are then examined for
symmetry and coaptation, and repair is done as described previously.
·
A notable percentage of cusp
prolapses are not obvious preoperatively but become evident after aortic root
repair and thus always merit reevaluation.
·
Root replacement using the
remodeling technique often necessitates an annular stabilization technique.
· The distal graft anastomosis is
then performed, taking care to avoid distortion of the commissures.
· The target effective height is 9
mm, which can be measured with a ruler while the aorta is still open.16
· TEE is critical for intraoperative
postrepair evaluation. This is done during the weaning off of cardiopulmonary
bypass and confirmed once off-pump on full heart ejection. Factors that
necessitate re-repair are the presence of more than grade I AI, any eccentric
AI jet, coaptation length less than 5 mm, and coaptation level below the aortic
annulus.3 Three-dimensional TEE may aid in the assessment of
coaptation surface area, which is a better surrogate for coaptation reserve.
· An algorithm proposed by le Polain
de Waroux et al.17 may be followed. Re-repair is warranted if the
coaptation tips are below the annulus. Any residual AI with a leaflet
coaptation length of less than 4 mm also warrants re-repair.
· Other notable factors are the AV
gradients for induced aortic stenosis and wall motion abnormalities in cases in
which coronary buttons were involved.
 |
Figure 12.11 Graft sizing using the NCC-LCC
commissure height as reference. (A) Meauring the NCC-LCC commissure height. (B)
This height corresponds to the height of the sinus portion
of the Valsalva graft. (C) This also corresponds to the graft diameter. (D) The
implanted graft, showing the lie of the NCC-LCC
commissure. (E) The graft is patterned according to the height of the LCC-RCC
and NCC-RCC commissures for subsequent implantation.
·
Repair of bicuspid aortic valve
(BAV) AI has been gaining acceptance during the last decade, showing a high
rate of reparability and a comparable rate of survival of patients to age-and
gender-matched groups.18
· BAV is often associated with
aortopathy and is thus commonly managed with a root replacement procedure,
especially in younger individuals.19
·
Type 0 BAVs have two symmetric
cusps and two commissures. The mechanism of AI is cusp prolapse due to excess
tissue. The degree of prolapse is assessed based on the nonprolapsed reference
cusp. In case both cusps are prolapsed, the goal is to restore the coaptation
level to the midpoint of the sinuses of Valsalva. Shaving and decalcification
can be done as needed20 (Fig. 12.12A).
·
A type 1 BAV is comprised of one
large nonconjoint cusp and two smaller fused cusps, with a median raphe or
pseudocommissure (see Fig. 12.12B and C). The conjoint cusp has a large base of
leaflet implantation. The mechanism of AI may be from a restrictive raphe or
prolapse of the conjoint cusp. If the raphe is only mildly fibrosed, it is
shaved off to improve the mobility of the cusp (Fig. 12.13). If the raphe is
restrictive, a conservative resection is done. If there is an adequate amount
of cusp tissue preserved, this may be closed primarily using locked or
interrupted 6-0 polypropylene sutures (Fig. 12.14). If there is no adequate
tissue, pericardial patching is performed as described previously. Refinement
of the repair may be done using plication or resuspension20 (see Fig. 12.8).
· In case of an associated root
replacement, the leaflet base implantation of the two cusps is maintained in a
symmetric fashion—that is, adjusted to an equal distribution, as in the case of
a type 1 BAV. The pseudocommissure is reimplanted in the graft at its natural
height.
 |
Figure 12.12 Biscupid aortic valve. (A) Type O valve. (B) Type 1 valve with
prolapsing conjoint cusp. (C) Type 1 valve with restrictive raphe.
Figure 12.13 Type 1 bicuspid aortic valve with noncalcified median raphe. (A) Mildly
thickened and fibrosed raphe. (B) Shaving of the raphe with intent of preservation.
|
· A unicuspid aortic valve (UAV)
frequently presents as aortic stenosis, but may also present as AI. It may also
be associated with aortopathy, and those patients present even younger than BAV
patients.
· The aortic pathology is first
addressed. The posterior commissure is usually normal and is preserved. A
tongue of aortic root on the opposing side is also preserved; this will be part
of the neocommissure for a bicuspidization technique. The dysplastic cusp
(usually the RCC) and adjacent raphe are resected. Two patches are tailored to
reconstruct the rest of the remaining two cusps and are joined to form the
neocommissure. Plication sutures are placed with the aim of achieving a target
height of 10 mm (Fig. 12.15).
·
Most cases of a quadricuspid
aortic valve (QAV) are incidentally diagnosed, suggesting that is it very much
compatible with life. It may present as aortic stenosis, AI, or a mix of both.
It may also be associated with aortopathy.
· If the cusps are well-preserved
and judged reparable, the procedure may be done with resection, reconstruction,
and tricuspidization or bicuspidization. Annular stabilization is warranted if
the root is preserved.
·
Other congenital defects should be
sought, such as an anomalous origin of the coronaries.
·
Most QAVs are not reparable and
are treated with an AVR.
 |
Figure 12.14 Type 1 bicuspid aortic valve repair with calcified median raphe. (A)
Resection of restrictive raphe. (B) Assessment of adequacy of remaining tissue by placing two arms of a polypropylene suture on the
margin of the conjoint cusps on either sides of the resected raphe. (C) If adequate tissue is available, primary reapproximation is done
using interrupted or running locked polypropylene 6-0 sutures.
Figure 12.15 Unicuspid aortic valve repair. (A) Dissection of the aortic root,
preserving a tongue of aortic tissue opposite that of the commissure. (B) Using pericardial patches, the cusps are reconstructed
to function like a symmetric bicuspid valve.
|
· Aspirin is administered routinely.
Blood pressure control is ensured to reduce the hemodynamic stress, help arrest
the disease process of aortic dilation, and reduce stress on repaired cusps.
·
Close follow-up is necessary to
optimize the monitoring of the durability of the AV repair. This is essential,
especially for those patients whose aortic roots were preserved and are
expected to dilate potentially over time. We recommend follow-up with
postrepair echocardiography at 3, 6, and 12 months and annually thereafter.
· Early mortality rate is low at 0%
to 2.0%.1-3,10,11,13,16 Overall survival is 80% to 87% at 9 to 10
years, which is comparable to patients who underwent AVR. Rates of major
adverse cardiac and cerebrovascular events and valve-related complications such
as thromboembolic events, bleeding, and endocarditis are low.1,3,4,8,11,13
· Freedom from AV reintervention is
89% to 92% at 10 years.1,2,16 The most common cause of AV
reintervention is recurrent AI. Risk factors for this include the presence of
residual AI postoperatively, short coaptation length, low level of coaptation,
and large aortic annulus.16,17
· The outcomes for AVr for isolated
AI is similar to that of AI associated with aortic dilation, independent of the
surgical technique used.3,8 There is a higher rate of AI recurrence
for AVr performed on type III (restrictive) leaflets, especially if rheumatic.3,17
·
Re-repair is still a good option
in case of initial failure, and freedom from AVR is 92% at 10 years.2
·
Results are comparable for AVr in
BAV and tricuspid aortic valve (TAV).2,13,18 Quantitative outcomes
results for UAV and QAV are still being developed, but recent reports have
shown that AVr in these valves may be considered as a feasible alternative to
outright replacement.21,22
· The most commonly involved cusp in
a prolapse is the RCC. However, the TEE is not able to evaluate the NCC and LCC
fully. The presence of an eccentric jet and/or a fibrous band is highly
suspicious for prolapse.
· There are excellent outcomes for
AVr in types I and II AI, especially for patients who have not yet manifested
with heart failure. This could promote consideration for an earlier surgical
intervention.
· Type III AI (restrictive) has a
less durable result for AVr and should have a lower threshold for AVR.
· AVr should be treated as a
specialized field of cardiac surgery, and triage to particular centers and
surgeons is advised.
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