Download Mitral Valve Repair

3.4
Mitral Valve Repair
Margo Winters, RN;
Pam Obriot, RN
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T
he first treatment for mitral valve
disease came shortly after the invention of the heart-lung bypass
machine.1 Direct visualization of the mitral valve made replacement surgery possible. The negative aspects of mitral valve
replacement, however, include possible
thromboembolism, hemolysis, and infection. This led cardiothoracic surgeons to
search for other methods to treat mitral
valve disease. As physicians began to
understand the complex function and
geometry of the mitral valve and the
subvalvular apparatus, repair techniques evolved, and mitral valve repair
soon became the gold standard in mitral
valve treatment.1
The number of mitral valve repair
cases has increased during the last decade
as new knowledge and increased experience has offered new treatments for
valvular repair.2 This article describes
typical mitral valve repair procedures
ABSTRACT
•
DISEASES THAT AFFECT the mitral valve include
mitral regurgitation, mitral stenosis, rheumatic heart
disease, and cardiomyopathy.
•
THE RESULTS OF DIAGNOSTIC procedures
are used to identify and confirm mitral valve disease, evaluate the patient’s anatomy, and determine
the severity of the disease.
•
AFTER THE PATIENT IS PREPARED for surgery, the surgeon performs an intraoperative transesophageal echocardiogram and the patient is
placed on cardiopulmonary bypass.
•
A REPAIR PROCEDURE (eg, annuloplasty, slidingplasty, chordal repair/transfer/replacement, valve
replacement) is performed depending on the
patient’s specific anatomical abnormalities. AORN J
85 (January 2007) 152-166. © AORN, Inc, 2007.
152 • AORN JOURNAL • JANUARY 2007, VOL 85, NO 1
performed on a daily basis at the
University of Michigan Health System,
Ann Arbor, Mich. Table 1 provides definitions of common medical terms associated with mitral valve repair.
MITRAL VALVE DISEASE PROCESSES
Two types of disease processes (ie,
geometric and valvular) affect the
mitral valve. The type of disease
process determines the appropriate
type of repair.
GEOMETRIC DISEASE. Geometric disease,
also referred to as ventricular disease,
is mitral regurgitation originating
within the left ventricle. In geometric
mitral disease, the left ventricle has
dilated so much that the mitral annulus has stretched and the mitral valve
leaflets can no longer coapt (ie, come
together).
Geometric disease can be ischemic or
nonischemic in origin. The most common form of ischemic heart failure is
myocardial infarction. In the presence of
coronary artery disease, narrowing or
obstruction of an artery causes decreased myocardial perfusion.3 Occlusion of the artery can be caused by
platelet aggregation, thrombotic embolism, dislodged calcium plaque, or coronary artery spasm. This ischemia leads
to necrosis of the myocardial tissue.
Persistent necrosis interferes with
myocardial function and eventually can
produce large areas of akinetic tissue (ie,
tissue that has lost the ability to move).3
There are many causes of nonischemic heart disease, but the heart’s
decreased ability to pump effectively
ultimately results in cardiomyopathy.
Some causes of nonischemic heart disease are hypertension and infections
such as endocarditis.3
The most common cause of geometric disease is dilated cardiomyopathy. In
geometric mitral disease, the valve and
© AORN, Inc, 2007
Winters — Obriot
JANUARY 2007, VOL 85, NO 1
TABLE 1
Common Medical Terms Associated with Mitral Valve Repair
Annulus
Mitral regurgitation
A ring-like structure; a fibrous band of tissue which
serves as the attachment point for the leaflets
A backward flowing of blood into the left atrium of
the heart caused by an incompetent mitral valve
Annuloplasty
Mitral stenosis
Surgical repair of a deformed annulus surrounding a diseased mitral valve
Obstruction to the flow of blood through the
mitral valve, usually caused by narrowing of the
valve orifice
Bicuspid valve
Subvalvular apparatus
A valve consisting of two leaflets (eg, the mitral
valve)
Coaptation
Chordae tendineae and papillary muscles within
the left ventricle that contribute to the geometry
and function of the mitral valve
The proper joining or fitting together of two surfaces (eg, mitral valve leaflets)
Trigone
Geometric mitral disease
Valvular mitral disease
A dysfunction of the mitral valve related to dilation of the left ventricle
Three angled section on the ends of the fibrous
region between the aortic and mitral valves
Valve dysfunction related to issues of the valve or
subvalvular apparatus
Left ventricular outflow tract
Zone of coaptation
A pathway from which blood exits the left ventricle and passes through the aortic valve
Rough surface of mitral valve leaflets that join
together during left ventricular systole
subvalvular apparatus are all normal.
The problem is within the ventricle,
which has become dilated to the extent
that the normal function of the valve is
disrupted.
VALVULAR DISEASE. Valvular mitral disease is a process in which the leaflets
and/or the annulus have become calcified and stiff or fused. In addition to calcification, valvular disease also may
include chordal shortening, which may
lead to mitral stenosis or regurgitation.
In the United States, valvular disease
most commonly is caused by rheumatic
endocarditis.4 Whatever the etiology,
most patients will have some degree of
dilation in the mitral annulus that must
be repaired.5
MITRAL VALVE ANATOMY
AND
PHYSIOLOGY
The bicuspid (ie, two leaflet) mitral
valve is located between the left ventricle and left atrium. The valvular complex consists of the annulus, leaflets,
chordae tendineae, and papillary muscles (Figure 1), and in a sense, the left
ventricle is the mitral valve. The annu-
lus, a fibrous band of tissue from which
the leaflets originate, is considered the
“hinge line” of the valve leaflets.6
Continuing out from the annulus, the
two leaflets (ie, anterior and posterior)
are pale yellow, thin, fibroelastic membranes whose anterior surfaces are relatively smooth. The posterior or ventricular surfaces are slightly irregular
because of the attachments to the chordae tendineae.
The anterior leaflet is also known as
the anteromedial, septal, or aortic
leaflet.4 The posterior leaflet, also
known as the mural leaflet, is further
divided into three cusps commonly
known as P1, P2, and P3. The three posterior cusps do not have separate functions; they have been named purely for
ease of describing mitral valve anatomy
and locations of regurgitation jets (ie,
flashes of backward blood flow).
The chordae tendineae are attached
to the inferior surface of the leaflets.
These white, cord-like tendons act only
as guides to assist in the coaptation of
the two leaflets. The chordae tendineae
AORN JOURNAL •
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Winters — Obriot
JANUARY 2007, VOL 85, NO 1
Figure 1 • Interior view of the heart showing the
mitral valve and subvalvar apparatus.
left atrium
posterior
leaflet
anterior
leaflet
chordae
tendinae
papillary
muscle
left
ventricle
preventing the backwards flow (ie,
regurgitation) of blood into the left atrium. The chordae tendineae guide the
leaflets into position; the chordae do not
pull the leaflets together. This forms a
tight closure (Figure 2), preventing
mitral regurgitation and allowing the
forward flow of blood through the left
ventricular outflow tract, through the
aortic valve, and out into the aorta. The
function of the mitral valve is regulated
by interaction of the components of the
mitral apparatus (ie, leaflets, chordae
tendineae, papillary muscles, ventricular
wall). The mitral apparatus contributes
to the normal geometry and function of
the left ventricle.
CAUSES
Figure 2 •
Normal
mitral valve
in closed
position.
also prevent the leaflets from billowing
or everting up into the atrium. If a primary chordae ruptures, the leaflet
everts into the atrium and is called a
“flail” leaflet. The chordae are attached
to the papillary muscles at the base of
the left ventricle.
Oxygenated blood originating from
the lungs flows through the pulmonary
veins and collects in the left atrium.
When pressure in the left atrium is
greater than the pressure in the left ventricle, the mitral valve opens allowing
blood to flow into the left ventricle. As
the intraventricular pressure rises, the
mitral valve closes (ie, the leaflets coapt)
154 • AORN JOURNAL
OF
MITRAL ABNORMALITIES
Numerous diseases affect the ability
of the mitral valve to function properly. Some of these diseases include mitral regurgitation, mitral stenosis,
rheumatic heart disease, and cardiomyopathy.
MITRAL REGURGITATION. Mitral regurgitation also is referred to as incompetence
or insufficiency. Regurgitation is a result
of the leaflets not coming together completely. An incompetent mitral valve
allows backflow of blood into the left
atrium. This backward flow in turn
leads to increased atrial volume and
eventually leads to backward flow of
blood into the lungs. This backflow into
the lungs leads to pulmonary edema. As
a result of this blood flow back-up,
many patients with mitral regurgitation
present to their primary care physician
with signs and symptoms of right heart
failure.2 The heart works harder to try to
compensate for the lost forward blood
flow; the ventricles may begin to hypertrophy (ie, thicken) because of the added
workload. If there is an ischemic area in
the left ventricle from a myocardial
infarction, the tissue can weaken and
become stretched, forming an aneurysm,
and become dysfunctional.
Winters — Obriot
MITRAL STENOSIS. Mitral stenosis refers
to the calcification of the leaflet and
annulus. A stenotic mitral valve also
leads to heart failure in much the same
way as mitral regurgitation, but instead
of blood moving backwards through
the mitral valve, mitral stenosis does
not allow enough blood through the
narrowed, fused, or calcified opening of
the mitral valve leaflets. The process
continues much the same as is seen in
mitral regurgitation, resulting in right
heart failure as blood volume builds up
in the lungs. Stenotic valve repair is
more complicated than repair of a dilated mitral annulus and requires more
experience on the part of the surgeon.5
The surgeon must make decisions about
excising calcified valvular tissue and
possibly replacing chordae or advancing leaflets. Each patient’s valve is different regarding the degree of stenosis
and involvement of the chordae tendineae and papillary muscles.
RHEUMATIC HEART DISEASE. Rheumatic heart
disease has decreased in the United
States in recent decades as a result of
effective antibiotic treatment of streptococcal (ie, strep) infections.4 Untreated
strep infections lead to rheumatic fever in
which antibodies produced by the body
to fight the infection also attack heart
valve leaflet tissue, most commonly the
mitral valve. In developing countries,
children often do not receive therapeutic
antibiotic treatments, so they constantly
are reinfected with strep. These countries
still have large populations with rheumatic heart disease, which is the leading
cause of cardiovascular death in young
adults.7
Infective endocarditis is a form of
rheumatic heart disease seen more
often in the United States. This disease
can be caused by contamination of the
blood as a result of illicit IV drug use,7
dental procedures, or surgical infections. The bacteria attach themselves
to the mitral valve leaflets causing
JANUARY 2007, VOL 85, NO 1
scarring; erosion; and ultimately, varying degrees of stenosis.
CARDIOMYOPATHY. Although cardiomyopathy can be caused by neuromuscular
or connective tissue disorders, alcohol
abuse, viral infections, or exposure to cardiotoxic substances, most cases are of unknown origin (ie, idiopathic).4 The most
common medical condition of patients
older than age 65 is congestive heart failure (CHF).3 Chronic CHF can lead to
dilated cardiomyopathy,
which causes the mitral
annulus to stretch, resultUntreated
ing in mitral regurgitation.
The geometric mitral
streptococcal
valve repair procedure to
resolve this problem is the
infections may
simplest procedure to perform. This geometric discause rheumatic
ease can be reversed with
the placement of an annuloplasty device. Mitral fever in which the
valve repair does not cure
body’s antibodies
CHF but can relieve the
acute symptoms of mitral
regurgitation and, ideally, fight the infection
keep the patient off the
but also attack
heart transplant list longer.
DIAGNOSTICS
heart valve leaflet
tissue, most
commonly the
mitral valve.
A variety of diagnostic
procedures are performed
to identify and then confirm mitral valve disease.
After mitral valve disease
is confirmed, diagnostic
procedures can help evaluate the patient’s anatomy
and determine the severity of the disease.
PHYSICAL EXAMINATION. During any routine physical examination, general practitioners can detect a heart murmur—
one sign of mitral regurgitation—by
auscultation. If a health care provider is
seeing a patient regularly, early detection of a heart murmur can result in
early diagnosis and, more importantly,
early treatment.
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JANUARY 2007, VOL 85, NO 1
CARDIAC CATHETERIZATION. In mitral valve
disease, cardiac catheterization is used to
confirm the diagnosis, assess ventricular
function, discover other cardiac lesions,
and evaluate coronary anatomy. Mitral
regurgitation is confirmed by left ventriculography during cardiac catheterization. With the patient under light sedation, a cardiinserts a catheter
A transesophageal ologist
through the femoral artery
injects an x-ray conechocardiogram and
trast agent into the chamber. Fluoroscopy is used
is a useful
to document the dye flow
as it regurgitates into the
intraoperative
left atrium.
TRANSTHORACIC ECHOCARDIOtool to more
GRAM. With acute mitral
regurgitation, a surface
accurately
echocardiogram can detect
determine valve abnormalities attributed to
a ruptured chordae papilanatomy, annular lary muscle or perforated
valve leaflet. The goal of
transthoracic echocardiosize, and the
gram is to identify the
degree of mitral degree of regurgitation
and valvular abnormality.5 Furthermore, addivalve disease
tional information on left
and assess for a atrial enlargement, right
ventricular enlargement,
regurgitant jet. and left ventricular dimensions can be obtained from
an echocardiogram.
TRANSESOPHAGEAL ECHOCARDIOGRAM (TEE). A
preoperative TEE allows anatomy to be
defined, assesses the degree of mitral
regurgitation, and measures left ventricular function. The direction of the
mitral regurgitation jet seen on a TEE
can identify which leaflet is flailing or
prolapsing. An anteriorly directed jet
indicates a posterior leaflet prolapse or
flail; whereas a posteriorly directed jet
indicates an anterior leaflet prolapse or
flail.1 A centrally directed jet may indicate annular dilation.
156 • AORN JOURNAL
Intraoperatively, the TEE is a useful
tool to more accurately
• determine valve anatomy,
• assess the degree of the mitral valve
disease,
• assess the degree of regurgitation,
• evaluate left ventricular function,
• assess annular size and degree of
enlargement, and
• assess for a regurgitant jet.
With the patient under anesthesia, a TEE
probe is placed in the patient’s esophagus so that the probe lies behind the
heart. The probe will remain in place
throughout surgery. After the surgical
repair has been performed, the surgeon
will clamp the cardiopulmonary bypass
(CPB) cannulas, fill the heart, and check
the repair using a TEE. Based on this
examination, the surgeon will decide if
the repair is adequate. If the surgeon
decides that additional repairs are needed, CPB will be reinitiated.
PREOPERATIVE PHASE
OF
SURGERY
In the preoperative holding room,
the circulating nurse assesses the
patient and verifies the patient’s identity. Before any narcotics are administered, the nurse confirms the proposed
procedure with the patient and his or
her family members, cross checking
the procedure with the surgical consent and OR schedule, and resolving
any discrepancies with the surgeon
before the patient is taken to the OR.
The nurse performs an examination to
assess the patient’s physical health status, emphasizing identification of cardiovascular risk factors, such as height,
weight, presence of hypertension or
diabetes, and use of alcohol or illicit
drugs. He or she further identifies the
patient’s relevant medical history (eg,
chronic illnesses, injuries, surgeries),
and obtains the patient’s medication
history, including medication allergies,
and any use of
• aspirin or other anticoagulants and
Winters — Obriot
the date of discontinuation of those
medications,
• prescribed medications,
• over-the-counter medications, and
• herbal therapies.
The circulating nurse notes the results
of pertinent laboratory studies, such as
chest x-rays and complete blood count
(CBC). He or she ensures that the patient has undergone blood typing and
cross-matching and that two units of
packed red blood cells are available.
After completing the history and physical examination and reviewing the
medical record, the nurse develops a
nursing care plan specific to this
patient and the proposed surgical procedure (Table 2).
INTRAOPERATIVE PHASE
The circulating nurse and anesthesia
care provider transport the patient to
the OR. To maintain the patient’s temperature during the preparatory phase
of the procedure, the circulating nurse
places a temperature-regulating blanket
on the patient after helping make the
patient comfortable on the OR bed and
securing the safety strap and arm
boards. The anesthesia care provider
places a radial arterial line in the
patient’s nondominant wrist and a central line with a pulmonary artery thermodilution catheter in the patient’s
right internal jugular.
OR SETUP. While the anesthesia care
provider places the monitoring lines,
the circulating nurse and scrub person
prepare the sterile field. Standard cardiac trays are used along with a valve
tray, mitral valve retractor, and the
appropriate valve sizers. The scrub
person prepares the aortic cannula, bicaval cannulae, left ventricular catheter
for ventricular decompression, and antegrade cardioplegia needle. The circulating nurse and scrub person perform
the sponge, needle, and instrument
counts. The circulating nurse confirms
JANUARY 2007, VOL 85, NO 1
that all sizes of required implants (eg,
mitral annular bands and rings) as well
as necessary suture for valve repair are
available.
PREPARING THE PATIENT. After the anesthesia care provider has secured the monitoring lines, all perioperative team
members including the surgeon and
anesthesia care provider actively participate in the surgical time out. The anesthesia care provider then
induces the patient under general anesthesia,
The direction of
after which the circulating nurse inserts an inthe regurgitant
dwelling urinary catheter with a temperaturejet helps
sensing probe. The circulating nurse ensures that
determine the
the patient is in an
anatomically correct, sumechanism of
pine position and pads
and tucks the patient’s
regurgitation
elbows at the patient’s
sides. The circulating
because the jet
nurse then places the
electrosurgical unit (ESU)
flows in the
dispersive pad on the
patient’s buttock.
opposite direction
The direction of the regurgitant jet helps deterof the flailing or
mine the mechanism of
regurgitation because the
prolapsing leaflet.
jet flows in the opposite
direction of the flailing or
prolapsing leaflet.1 The
anesthesia care provider ensures that preload, afterload, and blood pressure are
controlled during the TEE examination so
that the degree of mitral regurgitation is
not distorted. The anesthesia care
provider inserts the TEE probe, and performs a preoperative assessment of valve
function. Ideally, the anesthesia care
provider and the cardiologist should perform the TEE together because TEE interpretation may vary between observers.1
When the TEE is complete, the circulating nurse preps the patient’s surgical
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TABLE 2
Nursing Care Plan for Patients
Undergoing Mitral Valve Repair
Diagnosis
Risk for
alteration
in tissue
perfusion
related to
cardiopulmonary
bypass
•
•
•
•
•
Risk for
anxiety related
to knowledge
deficit and
stress of
surgery
•
•
•
•
•
Risk for acute
or chronic pain
related to surgical procedure
•
•
•
•
•
Risk for
fluid volume
imbalance
•
•
•
Risk for
inadvertent
hypothermia
Interim outcome criteria
Outcome
statement
Assesses for preexisting conditions that
predispose the patient to inadequate tissue
perfusion.
Identifies baseline tissue perfusion.
Collaborates in fluid management.
Monitors physiological parameters (eg,
peripheral pulses, urinary output, blood
pressure, filling pressures).
Evaluates postoperative tissue perfusion.
The patient maintains adequate tissue perfusion
throughout the
procedure as
demonstrated by
adequate urinary
output and blood
pressure and filling pressures within normal limits.
The patient
demonstrates
wound and
tissue perfusion consistent with or
improved
from identified preoperative baseline
levels.
Determines knowledge level, assesses
readiness to learn, and identifies barriers to
communication.
Explains sequence of events and reinforces
teaching about treatment options.
Provides instruction (ie, verbal, written) for
surgical procedure and discharge based on
identified need.
Communicates patient concerns to appropriate surgical team members.
Evaluates response to instruction.
The patient
verbalizes
decreased anxiety
and an ability to
cope.
The patient
demonstrates
knowledge of
the expected
response to
the procedure
and discharge
care.
Assesses patient’s pain preoperatively.
Identifies patient’s accepted postoperative
pain threshold.
Provides pain management instruction and
pain scale to assess pain control.
Implements pain management guidelines.
Evaluates patient’s response to pain management interventions.
The patient
demonstrates adequate pain management, and vital
signs are equal to
or improved from
preoperative
values.
The patient
demonstrates
and reports
adequate
pain control
throughout
the perioperative period.
Monitors for fluid deficit.
Monitors for signs of hypervolemia and
hypovolemia.
Monitors color and amount of urine output
from urinary catheter.
The patient’s urinary output is
within normal
range at discharge.
The patient’s
fluid, acidbase, and
electrolyte
balances are
consistent
with or
improved
from preoperative baseline
levels.
Monitors patient’s body temperature.
Implements thermoregulatory measures, to
include
• offering warm blankets and solutions
and
• applying temperature-regulating blanket or other warming devices when
applicable.
The patient’s temperature is within
normal limits at
discharge.
The patient is
at or returning to normothermia at
the conclusion of the
perioperative
period.
Nursing interventions
•
•
158 • AORN JOURNAL
Winters — Obriot
site from chin to knees and lateral to the
nipple line. The surgeon and scrub person then place the surgical drapes on the
patient and the suction and ESU pencil
on the sterile field.
PLACING THE PATIENT ON CPB. The surgeon
makes a median sternotomy incision
from the sternal notch to the xiphoid
process and opens the sternal bone using
a reciprocating saw. The surgeon uses
electrosurgery and bone wax to obtain
sternal-edge hemostasis and then secures
a Morse sternal retractor in place to
expose the patient’s heart. He or she then
opens the pericardium using Debakey
forceps and Metzenbaum scissors and
uses silk suture for pericardial stay stitches. After the pericardium is open, the surgeon dissects the aorta, superior vena
cava (SVC), and inferior vena cava (IVC)
and starts dissecting posteriorly to the
interatrial groove.
The anesthesia care provider administers heparin and checks the patient’s
activated clotting time (ACT) after three
minutes. The ACT test is used to monitor the effectiveness of high-dose heparin therapy administered during CPB
surgery. High-dose heparin anticoagulation during CPB is necessary to reduce
the risk of microthrombi that result from
the extracorporeal manipulation of
blood. The ACT test is used to demonstrate the inability of the patient’s blood
to coagulate rather than quantifying the
ability to clot.
The surgeon places the aortic, SVC,
and IVC purse-string sutures as the
scrub person brings the CPB lines to the
field and prepares them in anticipation
of cannulation. The surgeon places a
7-mm aortic cannula in the ascending
aorta and secures it with tourniquets
and a 0-silk stitch. He or she places SVC
and IVC cannulae and secures them
with tourniquets and silk ties. The surgeon places a left ventricular catheter in
the patient’s inferior pulmonary vein
and an antegrade cardioplegia needle in
JANUARY 2007, VOL 85, NO 1
the ascending aorta. The perfusionist
initiates bypass via the SVC only while
the surgeon completes posterior dissection to the interatrial groove.
Before the surgeon opens the left
atrium, the aorta must be crossclamped. If air is allowed
to enter the left atrium,
and subsequently, the left
ventricle, the air becomes High-dose heparin
an air embolism that may
travel up the ventricular
anticoagulation
outflow tract through the
aortic valve and into the
during
vessels coming off the
aortic arch that feed the
cardiopulmonary
cranium. An air embolism is a serious complibypass is
cation that can cause a
stroke. When the left atriused to reduce
um is dissected, the surthe risk of
geon places a cross clamp
on the aorta and applies
microthrombi
saline slush to the heart.
The perfusionist begins
that result from
to cool the patient to 32º
C (89.6º F) using cold
solutions and initiates the extracorporeal
total CPB.
MITRAL VALVE
REPAIR TECHNIQUES
manipulation
of blood.
Surgeons have a variety
of techniques to choose
from to repair the mitral valve (eg, annuloplasty, slidingplasty, chordal repair/
transfer/replacement, valve replacement). Vital to these repairs is proper
exposure of the mitral valve and its
complex valvular mechanism. The
appropriate technique can only be
decided after direct analysis of the
valve and its corresponding structures.
The circulating nurse must be prepared
for any and all changes in the procedure based on this analysis. The inventory of annuloplasty devices must be
maintained at sufficient levels and
readily accessible. The assistance of
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Winters — Obriot
Figure 3 • Placement of annuloplasty rings.
Figure 4 •
C-shaped
mitral valve
implant.
(Figure
courtesy of
Edwards
Lifesciences,
Irvine, Calif)
support service personnel, such as purchasing and inventory stocking personnel, is essential to an efficient system.
The circulating nurse also must maintain a stock of suture and be prepared
to use additional suture as the procedure progresses. Surgeon preference
sheets must be maintained and updated to indicate the preferred annular
devices and suture.
After the surgeon has exposed the
mitral valve apparatus, he or she opens
the patient’s left atrium using Metzenbaum scissors. The incision extends from
distal end of the intra-atrial groove to just
below the SVC. At this point, the surgeon
places the mitral valve retractor using a
basket and one malleable blade to expose
the annulus, leaflet tissue, or disrupted
chords. He or she uses a Debakey forceps
and nerve hooks to assess the mitral
leaflets and chords and to plan the repair.
160 • AORN JOURNAL
The surgeon looks for
redundant leaflet tissue
and calcified or disrupted
chords.
The surgeon uses a #15
blade and Jamison scissors to dissect any leaflets
or chords that need repair. The scrub person
prepares the disposable suture guides
and the 2-0 braided, coated, polyester
valve suture. The surgeon performs any
necessary
• leaflet repairs using a 4-0 braided,
coated, polyester suture;
• chordal repairs with a 5-0 monofilament polypropylene suture; and
• chordal replacement with 4-0
expanded, polytetrafluroethylene
(ePTFE) suture.
He or she then places the suture guides in
a triangle around the mitral valve retractor and places 2-0 braided coated polyester sutures in the mitral annulus, alternating green- and white-colored suture.
The surgeon tags the trigone sutures
with mosquito clamps on which rubbershods have been placed. When all
sutures are placed, the surgeon sizes the
annulus by measuring the anterior
leaflet from annulus to the beginning of
the zone of coaptation.5
Choosing the appropriate annulus
size is based on the theory that undersizing is appropriate for mitral regurgitation when it is related to left ventricular
enlargement.5 The circulating nurse confirms the size and type of implant with
the surgeon and delivers the implant to
the scrub person. In geometric disease, a
full ring is used to reduce the size of the
dilated annulus. In valvular disease,
however, a C-shaped ring is used to reinforce the repair. The scrub person places
the annular implant on the holder and
hands it to the surgeon. The surgeon
places individual 2-0 braided, coated,
polyester valve sutures in the annular
ring or band. One-third of the sutures are
Winters — Obriot
JANUARY 2007, VOL 85, NO 1
Figure 5 • Complete ring mitral valve implant.
(Figure courtesy of Edwards Lifesciences,
Irvine, Calif)
placed and then tagged with mosquito
clamps, and then the surgeon cuts off
and returns the needles to the scrub person. The surgeon repeats this procedure
for the remaining two-thirds of the valve
suture. After all valve sutures have been
placed in the ring, the surgeon slides the
ring down the suture and seats it along
the mitral annulus. The surgeon removes
the ring holder using a #15 blade and ties
down the individual valve sutures to
secure the ring and then closes the left
atrium using 3-0 monofilament polypropylene suture.
ANNULOPLASTY. The primary technique
used to repair the mitral valve is annuloplasty (Figure 3). Annuloplasty is aimed
at restoring the functional size and shape
of the fibrous band to which the leaflets
attach. When this band is returned to its
optimal size and shape, leaflet coaptation is restored. An important concept in
annular repair is that much of the dilation occurs at the more flexible posterior
portion of the annulus.1
The annular shape is restored using
an annular band. A variety of annular
bands are available to the cardiac surgeon. The rings range in the degree of
flexibility as well as shape. A C-shaped
band (Figure 4) allows the anterior portion of the annulus to be preserved and
function naturally, whereas a complete
ring (Figure 5) supports both the anterior and posterior dimension. The degree
of flexibility is important to consider
when choosing a band because the
band allows the annulus to adapt to
changes during the cardiac cycle.
When choosing a mitral annuloplasty
repair device, all of these variables must
be considered in relation to the etiology
of the patient’s specific disease pathology. For the patient with left ventricular
geometry changes, a three-dimensional
shaped band (Figure 6) may contribute
to the reversing/remodeling of the
rounded shape of the ventricle.
SLIDINGPLASTY. In addition to the annu-
loplasty, other repair techniques may
be employed based on analysis of the
structures of the individual valve.
Leaflet defects can be repaired using
the slidingplasty technique. These defects, commonly involving the P2 cusp,
can be repaired using a quadrangular
resection of the cusp and reapproximating the free edges of the remaining
P1 and P3 cusps. Undermining the
leaflet tissue along the annulus allows
the remaining tissue to approximate.
The surgeon then reattaches the leaflet
edges to the annulus using a 4-0
monofilament, polypropylene interrupted suture.
CHORDAL REPAIR, TRANSFER, OR REPLACEMENT.
Chordal repairs are accomplished based
on the etiology of the patient’s specific
Figure 6 •
Threedimensional,
shaped mitral
valve band
implant
(Figure
courtesy of
Edwards
Lifesciences,
Irvine, Calif)
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Winters — Obriot
SIDEBAR
Systolic Anterior Motion
S
ystolic anterior motion (SAM) may occur when
a relatively large posterior mitral valve leaflet [that
is coapting] with the anterior mitral valve leaflet
closer to its base [causes] both an anterior shift of
the coaptation point and an increase in the amount
of redundant leaflet tissue in the left ventricular
outflow tract.1(p179)
Lee et al2 reported that the incidence of SAM after
mitral valve repair is 1% to 2%. More recently, Sternik
and Zehr3 reported the incidence of SAM to be 4% to 5%.
Often, SAM is noted after the mitral repair is complete
and separation from cardiopulmonary bypass (CPB) is initiated. Walkes and Reardon4 assessed patients for SAM via
TEE after separation from CPB. Performing an intraoperative transesophageal echocardiogram (TEE) provides a
mechanism for diagnosing this phenomenon.
Correction of SAM often requires reestablishing CPB
and resecting the redundant anterior leaflet tissue in the
left ventricular outflow tract. Several preventative surgical techniques have been suggested to prevent the need
for an additional episode of CPB. Sternik and Zehn3 advocate tethering the mid segment of the anterior leaflet to
prevent the leaflet from flipping into the left ventricular
outflow tract. Quigley1 suggests using an elliptical excision of the body of the anterior mitral valve leaflet and
simple closure, thus reducing the height of the anterior
mitral valve leaflet by approximately 5 cm.
If SAM is observed, ionotropic agents and volume loading are instituted to reduce after-load. The TEE is then
repeated. If SAM is still observed, CPB is again established
and the initial repair is reexamined.
1. Quigley RL. Prevention of systolic anterior motion after
repair of severely myxomatous mitral valve with an anterior
leaflet valvuloplasty. Ann Thorac Surg. 2005;80:179-182.
2. Lee KS, Stewart WJ, Lever HM, et al. Mechanism of outflow tract obstruction causing failed mitral valve repair.
Anterior displacement of leaflet coaptation. Circulation.
1993;88:1124-1129.
3. Sternik L, Zehr KJ. Systolic anterior motion of the mitral valve
after mitral valve repair. Tex Heart Inst J. 2005;32:47-49.
4. Walkes JM, Reardon MJ. Status of mitral valve surgery.
Curr Opin Cardiol. 2004;19:117-122.
disease pathology. Elongation of the
anterior leaflet chord can be repaired by
invaginating the excessive chord into
the papillary muscle.8 The surgeon uses
a 5-0 polypropylene suture to bury the
chord into the papillary muscle. Chordal
162 • AORN JOURNAL
transfers can be performed to repair
ruptured chords. This can only be employed if suitable chords are available;
in which case, the surgeon uses a 4-0
polypropylene suture to secure the
chord to the leaflet. Chordal replacement can be used when suitable chords
are not available for transfer. A suitable
replacement material for chords is
ePTFE suture. This replacement technique consists of passing the suture
through the papillary muscle and then
through the leaflet edge. The surgeon
takes special care to determine the
length of the chord to ensure accurate
length of the replacement material.
VALVE REPLACEMENT. Mitral valve repair
and preservation of the subvalvular
apparatus (ie, chordae and papillary
muscles) contributes to the maintenance
of left ventricular geometry and function. The decision to replace a valve that
is beyond repair is based on the mechanism causing the regurgitation or stenosis. In the case of ischemic mitral valve
regurgitation, repair is almost always
possible because the underlying issue is
the changing geometry of the left ventricle. This changing geometry can be
reversed using an appropriately designed annuloplasty ring. Complex
mitral valve repair may be a challenge.
Replacement may be the only option for
severe valvular disease.
WEANING OFF CPB AND
CLOSING THE WOUND
The perfusionist begins to warm the
patient slowly to 37º C (98.6º F). The surgeon places temporary ventricular and
atrial pacing wires because electrolyte
imbalances, trauma to conductive tissue,
and previously undetected conduction
disturbances can contribute to postoperative dysrhythmias.4 The scrub person
passes the pacing cables off the field to
the anesthesia care provider who sets the
temporary pacemaker to fully automatic
pacing. The surgeon removes the aortic
Winters — Obriot
JANUARY 2007, VOL 85, NO 1
SIDEBAR
Protamine Sulfate
P
rotamine sulfate, a mixture of simple proteins obtained from the sperm or testes of suitable species
of fish, usually salmon, is used to neutralize the anticoagulation effect of heparin. It commonly is
used in instances of extracorporeal circulation, such as dialysis or cardiac surgery, in which cardiopulmonary bypass is used. Protamine also is used in some insulin preparations to delay the absorption of
insulin. Protamine does have anticoagulant effects when administered in the absence of heparin.1
Protamine is supplied in a 10 mg/mL solution for injection. The standard adult dosage is 1 mg IV for every
100 units of heparin remaining in the patient. Protamine must be administered slowly over a period of 10
minutes because administering it too quickly may result in severe hypotension and anaphylactic reaction.
Activated clotting time results should be used to monitor the effect of protamine in neutralizing heparin.
Adverse reactions to protamine are an antigen-antibody response that can result in cutaneous symptoms
(eg, skin flushing, pruritus) or systemic symptoms (eg, hypotension, bradycardia) and anaphylaxis.2
Precautions related to protamine administration should be taken for patients who have been exposed to protamine in the past through use of protamine-containing insulin or previous heparin neutralization during
dialysis or CPB. Caution should be used for patients with a history of fish allergy as they may develop a sensitivity reaction. Men who have had a vasectomy are at increased risk for a protamine reaction. During a
vasectomy the normal ejaculatory path is occluded and sperm are absorbed systemically. This systemic reabsorption may stimulate antibody production.3
Patients who have an increased risk for protamine reaction may be treated before initiation of CPB.
Loubser 4 demonstrated that activation of the anaphylactic response mediated by complement activation
is inhibited by high-dose methylprednisolone pretreatment before initiation of CPB. Diphenhydramine and
ranitidine also can be used as pretreatment for patients with increased risk factors for protamine reaction.
Health care providers administering protamine must be aware of possible risk factors that could result
in a protamine reaction. Protamine should only be administered by health care providers who are trained
in resuscitation techniques and the treatment of anaphylactic shock. Health care providers should continually assess the patient for flushing, nausea, vomiting, dyspnea, hypotension, and bradycardia and
then promptly treat the patient to avoid potential catastrophic outcomes.
1. DRUGDEX DRUG EVALUATIONS—Protamine. In: MICROMEDEX(R) Healthcare Series [subscription database
online]. Greenwood Village, Colo: Thomson MICROMEDEX; 2005.
2. MARTINDALE-The Complete Drug Reference—Protamine. In: MICROMEDEX(R) Healthcare Series [subscription
database online]. Greenwood Village, Colo: Thomson MICROMEDEX; 2005.
3. Porsche R, Brenner ZR. Allergy to protamine sulfate. Heart Lung. 1999;28:418-428.
4. Loubser J. Effect of methylprednisolone on complement activation during heparin neutralization. J Cardiovasc
Pharmacol. 1997;29:23-27.
cross clamp, and the perfusionist begins
to wean the patient off bypass as a cardiologist performs a postoperative TEE
to assess the function of the repaired
valve, comparing it to the preoperative
TEE. The surgeon also uses the TEE to
diagnose the presence of systolic anterior motion and to identify air in the left
ventricle. When it is confirmed that
there is no air in the heart, the surgeon
removes the left ventricular catheter
and antegrade cardioplegia cannulae. If
the surgeon identifies air in the heart,
the anesthesia care provider places the
patient in a slight Trendelenburg position. The surgeon then manually
manipulates the heart to allow the air to
remain in the left ventricle so the air can
be removed by the ventricular catheter.
After the patient is completely
weaned off CPB, the surgeon removes
the SVC and IVC cannulae. The surgeon
then inserts two mediastinal chest tubes
and secures them with 0-silk sutures.
The anesthesia care provider slowly
administers protamine, at which point
the circulating nurse and scrub person
begin the sponge, needle, and instrument counts. The surgeon is notified of
any discrepancies in the counts.
The surgeon removes the aortic cannula, closes the pericardium, and removes the sternal retractor. He or she
assesses the sternal edges for bleeding
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JANUARY 2007, VOL 85, NO 1
and uses bone wax and electrosurgery
as needed to control bleeding. The surgeon then closes the sternum using
eight #5 wires, and connects the chest
tubes to continuous suction via a threechambered, underwaterseal, pleural drainage system. The surgeon closes
the subcutaneous tissue
The nurse
using 0 and 2-0 monofilainitiates use of ment, polydioxanone suture and closes the skin
with 4-0 monofilament,
the incentive
poliglecaprone suture. The
spirometer with circulating nurse, anesthesia care provider, and surgeon transport the patient
coughing and
directly to the thoracic
intensive care unit (ICU).
deep breathing
immediately after
extubation and
helps the patient
sit on the side of
the bed within
six hours of
extubation.
POSTOPERATIVE PHASE
At University Hospital,
Ann Arbor, Mich, postoperative care is guided by a
critical pathway developed for the uncomplicated CBP procedure. The
surgical day includes direct admission to the thoracic ICU from the OR.
Initial postoperative laboratory tests include a CBC
with platelets; an electrolyte (eg, potassium)
count; and an arterial
blood gas. An ICU nurse ensures that a
chest x-ray is performed when the patient
is admitted to the ICU. The nurse ensures
that the patient regains and maintains
normothermia by using a temperatureregulating blanket and warmed IV solutions and obtains the patient’s vital signs,
including assessment of pain
• every 15 minutes until rewarming is
complete (ie, to 37° C [98.6° F]) and
then
• every four hours until discharged
from the ICU, or as needed.
The surgical resident extubates the
164 • AORN JOURNAL
patient as soon as possible (ie, usually
within four to eight hours) and places
the patient on 6 L of oxygen via nasal
cannula. The ICU nurse monitors the
patient’s mediastinal chest tubes and
pleural drainage system for excessive
(ie, more than 200 mL/hour) or increasing drainage. The ICU nurse replaces
potassium to maintain levels between
4.0 mEq/L and 5.2 mEq/L. He or she
administers morphine, the pain medication of choice, as needed and continues
IV administration of antibiotics (eg, cefazolin or vancomycin) for 48 hours. The
ICU nurse also administers heparin subcutaneously for platelet counts greater
than 100,000/mL3.
When the patient is extubated, the
nurse advances the patient’s diet from
clear liquids to full liquids, then to a
full liquid, low cholesterol, no-addedsodium diet. The nurse initiates use of
the incentive spirometer with coughing
and deep breathing immediately after
extubation and helps the patient sit on
the side of the bed within six hours of
extubation. The cardiologist sets the
atrioventricular-sequential pacemaker
to fully automatic pacing.
On the first postoperative day, the
surgical resident removes the pulmonary artery catheter and arterial lines
after the patient is determined to be
hemodynamically stable. The ICU nurse
removes the indwelling urinary catheter
on the first postoperative day. The nurse
weans the patient from morphine to use
of oxycodone/acetaminophen as soon
as the patient is able to take oral medications and according to the patient’s
acceptable pain threshold. The ICU
nurse prepares the patient for transfer to
the cardiac step-down unit, usually by
the first postoperative day.
In the cardiac step-down unit, the
assigned nurse encourages the patient
to ambulate in the halls three times per
day. The nurse advances the patient
from a full liquid to a regular diet with
Winters — Obriot
no added sodium and low cholesterol.
The sternal dressing remains in place
and the nurse reinforces it as needed.
The nurse adds one aspirin per day to
the patient’s medication regimen.
On the second postoperative day,
the surgical resident removes the
mediastinal chest tubes if drainage is
less than 50 mL in eight hours and
applies an occlusive dressing over the
chest tube sites for 24 hours. A chest
x-ray is taken after the chest tubes are
removed to ascertain that the patient’s
lungs remain reinflated. The surgical
resident removes the sternal dressing
and the nurse cleans the incision with
normal saline, after which the nurse
covers the incision only if the wound is
draining. The nurse and physical therapist ensure that the patient ambulates
four times a day. The nurse adds a
stool softener to the patient’s medication regimen and begins to teach the
patient and his or her family members
about the medication regimen to be followed at home after discharge.
On the third postoperative day, the
nurse ensures that discharge laboratory
tests are performed including a CBC
with platelet count. The surgical resident, nurse practitioner, or physician’s
assistant removes the pacing wires if the
patient’s heart rhythm is stable. The
nurse begins teaching the patient and
his or her family members about
wound care and makes final discharge
plans and orders any needed home supplies. The nurse then removes any
remaining peripheral IV lines.
The nurse discharges the patient on
the fourth postoperative day with
instructions about medications and
wound care. He or she instructs the
patient to continue using the incentive
spirometer and performing coughing
and deep breathing exercises. The
nurse ensures that an appointment is
made for a one-month follow-up in the
cardiac surgery clinic and gives the
JANUARY 2007, VOL 85, NO 1
patient instructions on how to contact
the surgical resident should any questions arise.
CONCLUSION
Treatment of mitral valve disease
has evolved from replacement to
repair. Improved understanding of the
underlying pathology has been an
important part of this evolution. A
variety of repair techniques used by
experienced surgeons provide patients
with the best possible outcomes.
The next phase in the evolution of
mitral valve repair is minimally invasive, robotic-assisted mitral valve
repair.9 This technique uses robotic technology along with a right-chest endoscopic approach. Although use of this
technique has been reported by other
centers in the United States, it currently
is not being used for mitral valve repair
at the University of Michigan. ❖
Margo Winters, RN, BSN, CNOR,
was the adult cardiac surgery education coordinator at University Hospital, University of Michigan Health
System, Ann Arbor, Mich, at the time
this article was written. Currently, she
is a clinical systems trainer for the
computerized physician order entry
project at the University of Michigan.
Pam Obriot, RN, BSN, is a RN first
assistant and cardiac surgery education
coordinator at University Hospital,
University of Michigan Health System,
Ann Arbor, Mich.
REFERENCES
1. Ho SY. Anatomy of the mitral valve.
Heart. 2002;88(suppl 4):iv5-10.
2. Seifert PC. Cardiac Surgery Perioperative
Patient Care. St. Louis: Mosby; 2002.
3. Finkelmeier BA. Cardiothoracic Surgical
Nursing. Philadelphia: Lippincott,
Williams & Wilkins; 1995:21-22.
4. Thompson JM, McFarland GK, Hirsh
JE, et al. Mosby’s Clinical Nursing. St Louis:
Mosby; 1986.
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5. Walkes JM, Reardon MJ. Status of mitral
valve surgery. Curr Opin Cardiol. 2004;19:
117-122.
6. Wells FC, Shapiro LM. Mitral Valve
Disease. Oxford: Butterworth-Heinemann,
Ltd; 1996.
7. Nowicki ER, Weintraub RW, Birkmeyer
NJ, et al. Mitral valve repair in northern New
England. Am Heart J. 2003;145:1058-1062.
8. Savage EB, Bolling SF. Atlas of Mitral
Valve Repair. Philadelphia: Lippincott,
Williams & Wilkins; 2006.
9. Woo YJ, Nacke EA. Robotic minimally
invasive mitral valve reconstruction yields
less blood product transfusion and shorter
length of stay. Surgery. 2006;140:263-267.
Computer System May Improve Weaning From Ventilators
P
atients with acute respiratory failure who are on
ventilation in the intensive care unit (ICU) have a
shorter duration on mechanical ventilation when
placed on a computerized system of weaning from the
ventilator, according to an Oct 16, 2006, news release
from The American Thoracic Society. Compared to typical physician-controlled management of the weaning
process, the computer-driven system resulted in a
reduction in patients’ time on mechanical ventilation
from 12 days to 7.5 days and a reduction in length of
ICU stays from 15.5 days to 12 days.
The computerized system introduces an automatic, gradual reduction in pressure support; initiates automatic spontaneous breathing trials; and
generates an incentive message when the patient’s
spontaneous breathing trial is successful. Additionally, patients who were weaned using this computerized system had a 30% reduction in total number of
ventilator-related complications, including
• reintubation,
• self-removal from ventilator assistance,
• need for noninvasive ventilation,
• mechanical ventilation longer than 21 days, and
• tracheotomy.
Computer-Driven System Reduces Patient Mechanical
Ventilation Time Significantly [news release]. New York:
American Thoracic Society; October 16, 2006. Available
at: http://www.eurekalert.org/pub_releases/2006-10
/ats-csr100506.php. Accessed October 27, 2006.
Poor Have Higher Risk of Death in Some Neighborhoods
R
esearchers investigating income and education
data in comparison to the socioeconomic status of
a person’s neighborhood determined that people of
low socioeconomic status living in affluent neighborhoods have an increased risk of death, according to
an Oct 31, 2006, news release from the Stanford
University School of Medicine, Stanford, Calif. This
trend was discovered after researchers analyzed data
from a previous study of 8,200 men and women from
82 neighborhoods in several California towns for a 17year period.
The researchers determined that 19 out of
every 1,000 women of low socioeconomic status
who lived in wealthier neighborhoods had died
after 17 years, compared to 11 out of every 1,000
women who lived in poorer neighborhoods. Although less dramatic, a similar trend was found in
men. The differences in death rates became more
pronounced over time, and were not found to be
related to age; cause of death; or risk factors such
166 • AORN JOURNAL
as obesity, hypertension, or smoking.
It is possible that the higher cost of living in
wealthy neighborhoods reduces the amount of disposable income that people of low socioeconomic
status have to spend on essential goods and services such as health care and healthy food. A poor
person in a wealthier neighborhood might not
have access to free social services made available
in low-income neighborhoods. It also is possible
that people of lower socioeconomic status, in comparing themselves with their neighbors, fare worse
in this socioeconomic setting for psychological and
social reasons.
Poor People in Well-To-Do Neighborhoods Face Higher
Death Rates, Stanford Study Finds [news release].
Stanford, Calif: Stanford University School of Medicine;
October 31, 2006. Available at: http://mednews.stanford
.edu/releases/2006/october/neighborhood.html. Accessed
November 6, 2006.