Download Mitral Valve Repair

Mitral Valve Repair
A. Marc Gillinov and Delos M. Cosgrove
Surgical repair of the dysfunctional mitral valve dates
back to the early twentieth century when several
surgeons developed techniques to try to correct mitral
stenosis. Mitral insufficiency was approached by only
a few surgeons because it was a more complex lesion
than mitral stenosis. Initial surgical attempts to treat
mitral insufficiency included maneuvers to block the
regurgitant jet and the introduction of the annuloplasty
concept by Glover and Davila6 in 1938. Lillehei et a17
were the first to attempt to correct pure mitral insufficiency by annuloplasty in 1957, and it appeared that
mitral valve repair would become an important procedure for cardiac surgeons. However, with the first
mitral valve replacement by Starr and Edwards8 in
1961, most surgeons abandoned attempts at mitral
valve repair, favoring the reliable results obtained with
valve replacement.
The modern era of mitral valve repair was initiated
by Carpentier. In 1971, Carpentier et a19 presented the
anatomic changes that occur in patients with mitral
insufficiency, laying the foundation for a systematic and
reproducible approach to mitral valve repair. During
the next 2 decades, many surgeons made important
contributions to the art and science of mitral valve
repair.1°-14 As a result of these innovations and the
excellent results obtained, mitral valve repair has
become the procedure of choice to correct mitral
insufficiency of all origins. l4
Numerous studies have documented that mitral valve
repair performed by standardized techniques is reproducible and associated with low operative morbidity
and r n ~ r t a l i t y . The
~~-~
advantages
~
of mitral valve repair over mitral valve replacement include a lower
operative mortality, better preservation of left ventricular function, and higher freedom from thromboembolism, anticoagulant-related hemorrhage, and endoyarditis.1°-14Given these advantages, an increasing proportion
of surgeons are using mitral valvuloplasty to treat
mitral insufficiency.
Although mitral valve repair is the preferred treatment for mitral insufficiency of all origins, it has its
greatest application and success in correcting mitral
insufficiency in patients with degenerative valvular
disease. 13-" Carpentier and others have shown that the
feasibility of mitral valve repair extends to 95% of
patients with degenerative valvular disease versus only
75% of patients with rheumatic o r ischemic valvular
disease.14 Degenerative disease is the most common
'-'
cause of mitral insufficiency in North America, accountable for more than 50% of cases in recent surgical
series. The most commonly encountered lesion in
degenerative mitral valve disease is posterior chordal
rupture; other lesions include anterior chordal rupture, chordal elongation, annular dilatation, and annular calcification.16 The posterior leaflet is more commonly affected by degenerative change than is the
anterior leaflet, and annular dilatation is limited to the
posterior mitral a n n ~ d u s .Using
~ , ~ ~a variety of repair
techniques tailored to the specific pathoanatomy encountered, Deloche et all4 have documented 93% freedom
from reoperation after repair of insufficient degenerative mitral valves.
Successful mitral valve repair includes four critical
components: (1) accurate assessment of the mechanism
of valvular dysfunction; (2) consistent and excellent
exposure of the mitral valve; (3) precise application of
repair techniques; and (4) intraoperative assessment of
the results of repair. Each of these components has been
standardized to ensure optimal results. The mechanism
of valvular dysfunction is determined by intraoperative
transesophageal echocardiography and surgical examination of the valve. When the heart is approached by
median sternotomy, exposure of the mitral valve is
obtained through a lateral left atriotomy, with adjunctive maneuvers used as needed. Specific repair techniques will be discussed in detail later. Intraoperative
transesophageal echocardiography is used to assess the
success of repair.
From 1985 to 1997, 1,072 patients had isolated
primary mitral valvuloplasty for degenerative mitral
valve disease at The Cleveland Clinic Foundation (Cleveland, OH). During this time period, techniques for
valve assessment, exposure, and repair evolved considerably. As noted, transesophageal echocardiography
has become essential for the determination of the
mechanism of mitral regurgitation preoperatively and
the assessment of the results of valve repair after bypass
surgery. The development of a self-retaining retractor
has greatly facilitated operative exposure of the mitral
valve. Specific repair techniques have evolved in response to an improved understanding of the physiology
of the mitral valve and studies documenting risk factors
for failed mitral valve r e ~ a i r . l ~ Procedural
-~l
risk
factors for failed mitral valve repair include the use of
chordal shortening techniques,18 residual mitral regur-
''
Operative Techniques in Thoracic and Cardiovascular Surgery, Vol3, No 2 (May), 1998: pp 95-108
95
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GILLINOV AND COSGROVE
gitation at the completion of repair,lg and failure to use
a ring annuloplasty.21 At Cleveland Clinic, leaflet prolapse is corrected by techniques other than chordal
shortening, and mitral regurgitation must be 1 or less
at the completion of repair. Virtually all patients receive
an annuloplasty, and this is accomplished using the
Cosgrove-Edwards Annuloplasty System (Baxter Health-
+
1
care, Newport Beach, CA).17With a design based on an
understanding of the normal physiology and pathoanatomy of the mitral valve, this annuloplasty system
includes a universally flexible band that produces a
measured plication of the posterior annulus. The Cosgrove-Edwards Annuloplasty System is easily applied,
and early results have been excellent.17
The patient is positioned supine on the operating room table with both arms tucked.
Standard monitoring lines, including a Swan-Ganz catheter if indicated, are placed. The
patient is induced with standard techniques and intubated with a single lumen endotracheal
tube. A transesophageal echo probe is placed and the valve is assessed. Several maneuvers
aid in the exposure of the mitral valve. (A) The pericardium is opened to the right of
midline, and the right pericardial edge is sutured under tension to the retractor.
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MV REPAIR
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(continued) (B) Adhesions over the left ventricle are lysed to the permit rotation of the
heart. The pericardial reflection onto the superior vena cava is incised, enhancing the
mobility of the right atrium when the left atrium is retracted.
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2
Cardiopulmonary bypass is established with a routine aortic cannulation and bicaval venous cannulation;
the cephalad cannula is placed through the right atrial appendage and directed into the superior vena cava.
Vacuum-assisted venous drainage (-50 mm Hg) allows for the use of two 20F venous cannulae in addition to
providing a dry field and avoiding venous air lock. Traction placed on an umbilical tape passed around the
inferior vena cava elevates the right side of the heart and contributes further to rotation. This brings the valve
into a plane that faces the surgeon. After the application of the aortic cross-clamp and administration of
antegrade and retrograde cardioplegia, the left atrium is opened widely. The left atriotomy begins at the
junction of the left atrium and right superior pulmonary vein and is continued cephalad behind the superior
vena cava; it is carried caudad behind the inferior vena cava as far as is necessary to ensure good exposure. A
self-retaining retractor with three adjustable blades maximizes the area of the left atriotomy and provides
consistent exposure. The first blade is posfioned at the cephalad extreme of the atriotomy. The second blade is
placed at the caudal aspect of the atriotomy and exerts traction toward the feet. The third blade is placed
between the first two blades. The table is elevated and rotated away from the surgeon. A systematic assessment
of the mitral valve and left atrium should now ensue. Jet lesions should be noted. Nerve hooks are then used to
define the presence and amount of chordal elongation. Because chordal elongation rarely involves the chordae
to the anterior lateral commissure, this area is used as a reference point against which the amount of prolapse of
both leaflets can be evaluated.
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MV REPAIR
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The visualization of specific components of the mitral apparatus may require additional
maneuvers. (A) The exposure of the posterior medial papillary muscle is enhanced by placing a
folded sponge between the diaphragm and the heart. (B) The anterior lateral papillary muscle is
exposed by placing a sponge anteriorly between the apex of the heart and the pericardium.
Additionally, pressure on the right ventricular outflow tract may aid in exposure of the annulus at
the anterolateral commissure.
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GILLINOV AND COSGROVE
4
(A) A flail portion of the posterior leaflet is treated by resection of the
unsupported portion of the leaflet. (B) One or two pledgetted sutures are used to
reinforce the annulus at the site of leaflet resection, and the leaflet is repaired with
running 5-0 multifilament nonabsorbable sutures. Although the middle scallop of the
posterior leaflet is most commonly affected, up to 60% of the posterior leaflet may be
resected. A posterior annuloplasty completes the repair.
MV REPAIR
5
Ruptured chordae in separate areas of the posterior leaflet are repaired by separate leaflet resections.
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GILLINOV AND COSGROVE
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To effectively create a new commissure, ruptured chordae at a commissure are treated by
resection of the unsupported portion of the leaflet and reapproximation of the anterior and
posterior leaflets and annulus.
MV REPAIR
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The free edge of the anterior leaflet may be supported by detaching a convenient secondary chord from the
ventricular surface of the anterior leaflet and suturing it to the unsupported free edge.
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A flail portion of the anterior leaflet may be supported by performing a quadrangular resection of
the posterior leaflet and transferring that portion of the posterior leaflet with its supporting chordae to
the anterior leaflet. The posterior leaflet is then repaired, as described previously.
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Sliding leaflet repair. This technique is used in conjunction with a quadrangular
resection when it is judged that the posterior leaflet is too tall (> 1.5 cm), posing an
increased risk for systolic anterior motion of the anterior leaflet of the mitral valve.
(A) After quadrangular leaflet resection, the remaining posterior leaflet is detached from
the annulus; a 1to 2 mrn scallop of posterior leaflet may be resected along the rim of its
attachment to the annulus. (B) With the posterior leaflet detached from the annulus,
annuloplasty sutures are placed. The segments of the posterior leaflet are then advanced
and reattached to the annulus using running 4-0 monofilament sutures; deep bites are
taken through the posterior leaflet, thereby imbricating tissue and further reducing the
leaflet height. (C) The site of the quadrangular resection is repaired as previously
described, and a posterior annuloplasty completes the repair.
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GILLINOV AND COSGROVE
10
All mitral valve repairs are reinforced by a posterior annuloplasty. In the case of isolated annular
dilatation, posterior annuloplasty may be all that is necessary for mitral valve repair. The ring size is
determined by measuring the area of the anterior leaflet. (A) Sutures are placed in the posterior annulus
from fibrous trigone to fibrous trigone and then passed through the annuloplasty band. (B) The handle is
removed to facilitate tying, but remains attached to aid in the removal of the frame. (C) When all sutures
have been tied. the frame is removed.
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Mv REPAIR
After completing all repair maneuvers, the valve is
inspected to ensure that there are no areas of leaflet
prolapse. The left ventricle is filled with saline to assess
leaflet mobility and coaptation. The left atriotomy is
closed in standard fashion and the heart deaired as
much as possible before removing the aortic crossclamp. After a period of recovery, the heart is allowed
to fill and eject, and mitral valve function is assessed by
transesophageal echocardiography. If the repair is
successful (mitral regurgitation 1+ or less), the patient
is separated from cardiopulmonary bypass and the
valve is once again assessed by transesophageal echocardiography. Hemostasis is achieved, pacing wires and
chest tubes are placed, and the wound is closed in the
standard fashion.
COMMENTS
At the Cleveland Clinic Foundation, from 1985 to 1997,
1,072 patients with degenerative mitral valve disease
had isolated primary valve repair for mitral insufficiency. The mean age of these patients was 58 & 12.5
years (range, 18-84 years); 65% were men. The repair
techniques that were used included annuloplasty (89%0),
posterior leaflet resection (8l%0), posterior sliding repair (22%), chordal transfer (21%), and chordal shortening (10%). There were three hospital deaths (0.3%).
Long-term follow-up was available in 1,062 of 1,069
hospital survivors (99.3%). Ten-year actuarial survival
was 81%. Risk factors for late death included anterior
leaflet prolapse, chordal shortening, annuloplasty alone,
older age, renal dysfunction, and atrial fibrillation. At
10 years, freedom from thromboembolism was 8870,
from endocarditis 99%, from anticoagulant-related hemorrhage 9970, and from reoperation 93%. Of the 30
patients who required reoperation for late mitral valve
dysfunction, 16 (53%) had repair failure secondary to
progressive degenerative disease. Anterior leaflet prolapse, chordal shortening, annuloplasty alone, leaflet
resection without annuloplasty, and no intraoperative
echocardiogram increased the risk of late reoperation.
These long-term results of mitral valve repair for
degenerative mitral valve insufficiency parallel those
obtained by Carpentier's group. l4 Although the standardization of techniques for mitral valve repair has
allowed widespread application of this operation, refmement and innovation continue in this area of cardiac
surgery. Significant changes in mitral valve repair
technique have occurred during the last decade. As
noted previously, the introduction of transesophageal
echocardiography has been of great value in determining the mechanism of mitral regurgitation and assessing
the success of subsequent repair. Development of the
sliding leaflet technique has allowed successful mitral
valve repair in the setting of a tall posterior leaflet.
Careful analysis of the results of large series has shown
that chordal shortening increases the risk of late repair
failure.18.20At this time, anterior leaflet prolapse should
be corrected by chordal transfer or the creation of an
artifical chordae.20J2Failure to perform a ring annuloplasty increases the risk of repair failure.'l Therefore,
nearly all mitral valve repairs in adults should be
accompanied by a ring annuloplasty. An improved
understanding of the anatomy and physiology of the
mitral annulus suggests that a flexible posterior annuloplasty will preserve physiological function and correct
annular dilatation.17 An analysis of the first 300 patients who received the Cosgrove-Edwards Annuloplasty System showed excellent results, with no instances of systolic anterior motion of the mitral valve
and 97% freedom from reoperation at 1 year.
The most dramatic technical change in mitral valve
surgery during the last 10 years has been the recent
development of minimally invasive approaches to the
mitral valve. Successful mitral valve repair has been
accomplished using a right thorac0tomy,2~right parasternal in~ision,'~partial stern~tomy,'~
and port-access
techniques.26Each approach provides good exposure of
the mitral valve and allows either mitral valve repair or
replacement. At Cleveland Clinic, the current preferred approach for isolated mitral valve repair is the
partial sternotomy. This approach, coupled with a
transseptal incision, provides excellent exposure of the
mitral valve. Early results with minimally invasive
mitral valve surgery have been encouraging.
Mitral valve repair is the procedure of choice to
correct mitral regurgitation caused by degenerative
disease. Although standardized techniques for mitral
valve repair were developed more than 2 decades ago,
operative techniques continue to evolve. Continued
assessment of the results of mitral valve repair and the
recent interest in minimally invasive approaches to the
mitral valve will undoubtedly result in further refinement in techniques for mitral valve repair.
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GILLINOV AND COSGROVE
20. Gillinov AM, Cosgrove DM, Lytle BW, et al: Reoperation for failure of
mitral valve repair. J Thorac Cardiovasc Surg 113:467-475,1997
21. Cohn LH, Couper GS, Aranki SF, et al: Long-term reaults of mitral valve
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From the Department of Thoracic and Cardiovascular Surgery, The Cleveland
Clinic Foundation, Cleveland, OH.
Address reprint requests to Delos M. Cosgrove, MD, Department of Thoracic and
Cardiovascular Surgery/F25, The Cleveland Clinic Foundation, 9500 Euclid Ave,
Cleveland, OH 44195.
Copyright 0 1998 by W.B. Saunders Company
1085-5637/98/0302-0002$8.00/0