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MITRAL VALVE DISEASE
Shahbudin H. Rahimtoola
Maurice Enriquez-Sarano
Hartzell V. Schaff
Robert L. Frye
i
MITRAL STENOSIS
Definition, Etiology,
and Pathology
Mitral stenosis(MS), an obstructionto blood flow between the left
atrium (LA)and the left ventricle (LV),is caused by abnormal mitral
valve function.In virtually alladult patients, the cause of MS is pre
vious rheumatic carditis. About60percentof patients with rheumatic
mitral valve diseasedo not giveahistory of rheumatic feverorchorea,
and about50percent of patients with acute rheumatic carditis do not
eventually have clinical valvular heart disease. Other causes of MS
are uncommon, but obstruction to LV inflow can be congenital or
due to activeinfective endocarditis,neoplasm, massive annular cal
cification, systemic lupus erythermatosus, carcinoid,methysergide
therapy, Hunter-Hurler syndromes, Fabry's disease,Whipple's dis
ease,rheumatoid arthritis. left atrial myxoma,massive left atrial ball
thrombus, andcortriatum.
Acute rheumatic carditis is a pancarditis involving the peri
cardium, myocardium, and endocardium. In temperate climates and
developed countries,there is usuallya long interval (10 to 20years)
between an episode of rheumaticcarditis and the clinical presenta
tion of symptomatic MS. In tropical and subtropicalclimates and in
less developed countries,the latent period is often shorter, and MS
may occur during childhood or adolescence.
The pathologic hallmark of rheumatic carditis is an Aschoff's
nodule. Rheumatic valvulitis results in scarring and fusion. The
combination of commissural fusion,valve leaflet contracture.and
431
fusion of the chordae tendincae results in a narrow,funnel-shaped
orifice."
Pathophysiology
The pathophysiologic features.ofMS allresult from obstructionof
theflow of blood between theLA and the LV. With reduction in valve
area,energy is lost to friction during the transport of blood from the
LAto the LV. Accordingly,a pressure gradient is present across the
stenotic valve.
The pressure gradient between the LA and the LV increases
markediy with increased heart rate or cardiac output (CO); this is
responsible for LA hypertension. The LA gradually enlarges and
hypertrophies.Pulmonary venous pressure rises with LA pressure
increase and is passivelyassociated with an increase in pulmonary
arterial (PA)pressure.In up to 20percent of patients, the pulmonary
vascular resistarnce is alsoelevated,which furtherincreasesPA pres
sure.PA hypertension results in right ventricular(RV)hypertrophy
and RV enlargement. The changes in RV functioneventually result in
right atrial (RA)hypertension and enlargement and systemic venous
congestion; frequently,tricuspid regurgitation also occurs.
Pulmonary venous hypertension alters lung function in several
ways. Distributionof blood flow in the lung is altered,with a rela
tive increase in flow to the upper lobes and therefore in physiologic
dead space.Pulmonary compliance generallydecreases withincreas
ing pulmonary capillary pressure.increasingthe work of breathing.
particularly during exercise. Chronic changes in the pulmonary capil
laries and pulmonary arteries include fibrosis and thickening.These
changes protect the lungs from the transudation of ffuid into the
alveoli(alveolarpulmonary edema).
Long-standing MS with severe PA hypertension and resultant
RV dysfunction may be accompanied by chronic systemic venous
hypertension. Tricuspid regurgitation is frequently present,even in
the absence of intrinsic disease of this valve.
Clinical Manifestations
HISTORY
An asymptomatic interval is usually present between the initiating
event of acute rheumatic fever and the presentationof sympiomatic
MS. Initially, there is little or no gradient at rest, but with increased
cardiac output,LA pressure rises and exertionaldyspnea develops.
As mitral valve obstructionincreases,dyspnea occurs at lowerwork
levels. The progression of disability is so subtleand protracted that
patients may adapt by circumscribing their lifestyles. It begomes
*Mitral stenosis section written by Dr.Rahimtoola.Mitral regurgitation section
written by Drs. Enriquez-Sarano. Schaff. and Frye.
�TNT VA
iniperative, then,to document what activities the patient can perform
thout symptoms and at what activity level symptoms begin.
As obstructionprogresses,the paticnts note orthopnca and parox
ysmalnocturmaldyspnea. apparently resulting from redistribution of
blood to the thorax on assuming the supine position. With severe
MS and elevatedpulmonary vascular resistance. fatiguerather than
dyspnea may be the predominant symptom. Dependent edema, nau
sea,anorexia,and right-upper-quadrantpain reflectsystemic venous
congcstion resulting from elevatedsystemic venous pressure and salt
and water retention. Symptoms ofRV failure (hepatomegaly, edema,
and ascites) may predominate in patients with severepulmonary hy
pertension.
Palpitations are a frequent complaint in patients with MS and
may representfrequent premature atrial contractionsor paroxysmal
atrial fibrillation/fluter. Of patients with severe symptomatic MS,
50percent or more have chronic atrial fibrillation.
Systemic embolism, a frequent complication of MS, may result
in stroke, occlusion of extremity arterial supply, occlusion of the
aorticbifurcation, and visceral or myocardial infarction. Hemoptysis,
hoarseness, and exertionalchest pain are infrequentmanifestations
of MS.
Progression of symptoms in MS is generallyslow but relentless.
Thus,asudden change in symptoms rarey reflects a change in valve
obstruction.Rather.there is usuallya noncardiac precipitating event
or paroxysmal atrial fibrillation.
PHYSICAL FINDINGS
During the latent, presymptomatic interval, incidental physical find
ings may be normal or may provide evidence ofmild MS.Frequently,
the only characteristic findingnoted at rest will be a loud S and a
presystolicmurmur. A short diastolic decrescendo rumble may be
heard only with exercise.In patients with symptomatic stenosis,the
findingsare more obvious, and careful physical examination usually
leads to the correctdiagnosis (seealso Chap. 1).
The jugular venous pressure may. be normal or may show evi
dence of elevated RA pressure.A prominent a wave is a result of
RV hypertcnsion/hypertrophy or of associated tricuspid stenosis. A
prominent v wave is caused by tricuspid regurgitation. Atrial fibril
lation produces an irregular venous pulse with absent a waves. The
chest findingsmay be normal ormay reveal signs of pulmonary con
gestion with ralesorpleural fAuid (dullnessand absent breath sounds).
Marked LA enlargement may produce egophony at the tip of the left
scapula.
The precordium is usuallyunremarkable on inspection.On palpa
tion, the apicalimpulseshould feel normalor be tapping.An abnor
mal LV impulse suggests diseaseother than isolated MS. A diastolic
thrillis usualy appreciatedonly when the patient is examined in the
imperative,then,to document what activities the patientcán perform
without symptoms and at what activity level symptoms begin.
Asobstructionprogresses,the patients note orthopnea and parox
ysmal nocturnaldyspnea, apparently resulting from redistribution of
blood to the thorax on assuming the supine position. With severe
MS and elevatedpulmonary vascular resistance, fatigueratherthan
dyspnea may be the predominant symptom. Dependent edema, nau
sea,anorexia,and right-upper-quadrantpain reflect systemic venous
congcstion resulting from elevatedsystemic venous pressure and salt
and water retention. Symptoms ofRV failure (hepatomegaly, edema,
and ascites) may predominate in patientswith severe pulmonary hy
pertension.
Palpitationsare a frequent complaint in patients with MS and
may represent frequent premature atrial contractionsor paroxysmal
atrial fibrillation/flutter. Of patients with severe symptomatic MS,
50percent or more have chronic atrial fibrillation.
Systemic embolism, a frequent complication of MS,may resultin stroke,occlusion of extremity arterial supply, occlusion of the
aorticbifurcation,and visceral or myocardial infarction. Hemoptysis,
hoarseness, and exertionalchest pain are infrequent manifestations
of MS.
Progression ofsymptoms in MS isgenerallyslow but relentless.
Thus, a sudden change in symptoms rarely reflccts a change in valve
obstruction.Rather, there is usuallyanoncardiac precipitating event
or paroxysmal atrial fibrillation.
PHYSICAL FINDINGS
During the latent, presymptomatic interval, incidental physical find
ingsmay be normalor may provide evidence of mild MS. Frequently,
the only characteristic finding noted at rest will be a loud S and a
presystolicmurmur. A short diastolic decrescendo rumble may be
heard only with exercise.In patients with symptomatic stenosis,the
findingsare more obvious, and carefulphysical examination usually
leads to the correctdiagnosis (seealso Chap. l).
Thejugular venous pressure may. be normal or may show evi
dence of elevated RApressure.A prominent a wave is a resultof
RV hypertension/hypertrophy or of associated tricuspid stenosis. A
prominent v wave is caused by tricuspid regurgitation. Atrial fibril
lation produces an irregular venous pulse with absent a waves. The
chest findingsmay be normal ormay reveal signsof pulmonary con
gestionwith rales or pleural fluid (dullncssand absentbreathsounds).
Marked LA enlargement may produce egophony at the tip of the left
scapula.
The precordium is usuallyunremarkable on inspection.On palpa
tion, the apical impulse should feel normal or be tapping.An abnor
mal LV impulse suggests diseaseother than isolated MS. A diastolic
ghrill is usually appreciatedonly when the patient is examined in the
left lateral decubitus position.When PA hypertension is present,a
sustainedRV lift along the left sternal border and pulmonic valve
closuremay be palpable.
On auscultationin the supine position,the only abnormality ap
preciated may be the accentuatcd Si, which is caused by flexible
valve leaflets and the widc closing excursion of the valve leaflets.
Failure to examine the paticnt in the left lateral decubitus position
accounts for mostof the nisscd diagnoses of symptomatic MS. The
diastolic numble is heard best with the bell of the stcthoscope applicd
at the apical impulse. Nevertheless, the murmur may be localizcd,
and the region aroundthe apical impulse alsoshould be auscultated.
The opening snap (OS)occurs when the movement of thc domed
miralvalve into theLV is suddenly stopped. It is heard best with the
diaphragm and is oftcn mostcasilyappreciatcdmidway between the
apex and the left stcrnalborder. In this intermediate region, the Sj.
P2.and the OS can bc identified.
The OS occurs after the LV pressure falls below LA pressure
in early diastole. Whcn LA pressure is high. as in severe MS,the
snap occurs carlier indiastole. Although the OS is present in most
cases of MS,it is absent in patients with stiff, fibrotic, or calcified
leaflcts. Thus,absence of the OS in severeMS suggests that mitral
valve replacement rather than commissurotomy may be necessary.
The low-pitched diastolic rumble followsthe OS and is best heard
with the bell of the stethoscope.In somepatients with low cardiac
outputor mild MS, brief exercise. such as sit-ups or walking. is ad
equate to increase flow and bring out the murmur. The murmur is
low-pitched. rumbling, and decrescendo. In general,the more severe
theMS. the longer the murmur. Presystolic accentuation of themur
mur occurs in sinus rhythm and has been reported even in atrial
fibrillaion.
The two most important auscultatorysigns of severe MS are a
shortAz-OS interval and a full-length diastolic rumble. The diastolic
murmurmay not be full-length in severeMS if the strokevolume is
low and there is no tachycardia.
Systolicmurmurs also may be heard in associationwith themur
mur of MS. A blowing murmur at the apex suggests associated mi
tral regurgitation. whereas a systolic blowing murmur heard best
at the lower left stemal border that increases with inspiration usu
ally signifies tricuspid regurgitation. The Graham Steellmurmur is
a high-pitched diastolic decrescendo murmur of pulmonic regurgi
tation caused by severe PA hypertension. In most patients with MS,
such a murmur usually indicatesaortic regurgitation. In general, a
left-sided S3 is not compatible with severe MS,with the possible
exception of concomitant severe AR and/or significant LV systolic
dysfunction. If an S3 and a rumble are present,mitral regurgitation
isusuallythe predominant lesion.
CHEST ROENTGENOGRAM
The posteroanteriorand lateral chestfilmsareoftensotypical that ex
perienced clinicians can makethe tentative diagnosisfrom them.The
thoraciccage is normal. The lung fields show evidence of elevated
pulmonary venous pressure.Blood flow is more evenly redistributed
to the upper lobes, resulting in apparent prominence of upper-lobe
vascularity. Increased pulmonary venous pressure results in transu
dation of fuid into the interstitium. Accumulation of fuid in the
interlobularsepta produces linear streaksin the bases,which extend
to the pleura (Kerley B lines). Interstitial fluid may also be seen as
perivascularor peribronchialcuffing (Kerley A lines). With transu
dationof fuid into the alveolarspaces,alveolarpuimonary edema is
seen. These changes represent long-standing elevated LA pressure.
PA hypertension results in enlargement of the main PA and right and
left main pulmonary arteries.
The cardiac silhouetteusually does not show generalized car
diomegaly, but the LA is invariablyenlarged.In the posteroanterior
chest flm, LA enlargement is recognized by a density behind the
RA border (doubleatrial shadow),prominence of theLA appendage
on the left heart border between the main PA and LV apex, and el
evation of the left main bronchus. The lateral film shows the LA
bulging posteriorly. The combination of a normal-sized LV,enlarged
LA,and pulmonary venous congestion should immediately raise the
possibility of MS. Mitral valve calcification is occasionally seen on
theplain chest x-ray.
ELECTROCARDIOGRAM
Patientsin sinus rhythm may have a widened P wave caused by inter
atrial conduction delay and/or prolonged LA depolarization. Clas
sically, theP wave is broad and notched in lead Il and biphasic in
lead Vi: it measures 0.12 s or more. Atrial fibrillation is common.
LV hypertrophy is not present unless there areassociatedlesions. RV
hypertrophy may be present if PA hypertension is marked.
CUNICAL INDICATIONS OF SEVERE
MITRAL STENOSIS
Some clinical featuresmake it virtually certain that MS is severe.
These include (1)moderate to severe PA hypertension, as indicated
by clinical andECG evidence ofRV hypertrophy or PA hypertension
or both, and/or (2)moderate to severe elevationof LA pressure as
indicated by orthopnea, a short P-0S interval, a diastolic rumble
that occupies the whole lengthofa long diastolic interval in patients
with atrial fibrillation, and pulmonary edema on the chest x-ray. In
both these clinical circumstances, one must be certain that there is
no other cause forelevatedLA pressure and that LA hypertension is
notcaused mainly by acorrectabletransient elevationofLV diastolic
pressure.
Laboratory Tests
ECHOCARDIOGRAPHY/DOPPLER
ULTRASOUND
Echocardiography/Doppler ultrasound has proved tobe both sensi
tive and spcciic forMS when adequate studiesare done. The charac
teristic M-mode echocardiographic featuresareadecreased EF slope
of the anterior mitral leaflet. Two-dimensional (2D) echocardiogra
phy willdemonstrate the valve orifice and allow calculationof mitral
valve area.Doppler echocardiography willprovide estimates of the
gradient across the valve and of pulmonary artery pressure.
Transesophageal echocardiography (TEE)is a useful technique
toassess LA thrombus,the anatomy ofthe mitralvalve and subvalvu
lar apparatus, and the suitability of the patient for catheter balloon
commissurotomy or surgicalvalve repair.Echocardiography/Dopplerultrasound is a most usefultest in MS
and shouldbe performed in all patients. It is essentialto determine
suitability of the valve for commissurotomy and/or repair and to
deternine the likely result.
CARDIAC
CATHETERIZATION/ANGIOGRAPHY
In most patientswith disabling symptoms from presumed MS,right
and left heart catheterizationshould be performed as part of a pre
operative assessment. Simultaneous measurement of cardiac output
and the gradient between theLA and the LV and calculationof valve
area remain the "gold standard" for assessing the severity of MS.
LV angiography assesses the competence of the mitral valve, an
important determinant of operability for mitral commissurotomy.
Quantification of LV function provides a useful prognostic indica
tor of operative and late survival and of the expected functional
resuit. Aortic valve function should be evaluated in all patients.
Selective supraventricular aortography should be performed in all
patientsunless there is a contraindication.Tricuspid valve function
can be assessed when there is a question of coexisting lesions. In
certaincircumstances ,dynamic exercise in the catheterizationlabo�
ratory with measurement of mitral valve gradient,CO,and LA and
PA pressures can be extremely useful. Selectivecoronary arteriog
raphy establishes the site, severity, and extent of coronary artery
disease and should be performed in patients with angina, Lydys
function,and/or risk factorsfor coronary arterydisease and in those
35 years of age orolder who arebeing considered for interventional
therapy.
OTHER LABORATORY STUDIES
Inmost clinical situations, other investigationsare not needed. Oc
casionally, a treadmillexercise test to evaluate functionalcapacity
may be very useful clinically-for example, when a patient denies
symptoms in spite of severe hemodynamic abnormalities.
Natural History and Prognosis
Thepopulation presenting with MS is changing because of the sharp
decline in the incidence of acute rheumatic feverin the past40years.
Native-borm American citizens with symptomaticMS are presenting
at an older age. Young adults in the third and fourth decades with
symptomatic MS are more likely to come from low socioeconomic
backgrounds and from the inner city or to be immigrants, partic
ularly from Latin America, the Middle East, Africa, or Asia. The
mechanism for the progression from no symptoms to mild to severe
symptoms is progressive stenosisof the mitral valve.Approximately
50percent of patients develop symptoms gradually.Sudden deteri
oration is usually the result of atrial fibrillation, systemic emboliza
tion,and other conditions that result in tachycardiaand/or increased
cardiac output.
The 10-year survivalof patients with MS who are asymptomatic
is approximately 84 percent,and that of thosewho are mildly symp
tomatic is 34to 42percent.Patients in theNew York Heart Associa
tion functionalclassIV have a very poor survivalwithout treatment:
42 percent at 1 year and 10 percent or less at5years.All are dead
by 10 years.
Medical Treatment
All streptococcal infections should be diagnosed rapidly and cor
rectly treated. All patients with known previous acute rheumatic
fever/rheumatic carditis with or without obvious valvedisease should
receive appropriate antibiotic prophylaxis against recurrent strep
tococcal infection (Table 23-1). Prophylaxis against infective en
docarditisis a lifelong requirement. If atrial fibrillation is present,
however,digitalis plays a critical role in controllingventricularrate.
In selected patients, beta-adrenergic blocking agents, diltiazem,or
amiodarone may be added if digoxin alone is not satisfactory in
controlling ventricularrate at rest or on exercise.Diureticsreduce
pulmonary congestion and peripheral edema and allow most pa
tients freedom from severe salt restriction. For the patient with mild
symptoms, maintenance of sinus rhythm isdesirable. Cardioversion
of atrial fibrillation and maintenance of sinus rhythm using antiar
rhythmic therapy with either digitalis and quinidine or digitalis and
amiodarone should be offered to these patients. In patients who
need interventionaltherapy,cardioversion is usuallyperformed after
TABLE 23-1
SECONDARY PREVENTION O�F RHEUMATIC FEVER
Agent Doe Mode
Benrathine
PenicallinG
Penicillin V
1,200,000Uevery
4 weeks (every
3weeks fot
high-risk patients
such as those
with residual
carditis)
250mg twice daily
Intramuscular
Oral
Sulfadiazine
For individuals
allergic to
penicillin and
sulfadiazine:
Erythromycin
0.5 gonce daily for
patients s27kg
(601b)
1.0g once daily for
patients >27kg
(60 1b)
250mg twice daily
Oral
Oral
"High-nsk patients include those with residual rheumatic carditis as well as
patients from economically disadvantaged populations.
SoURCE:Bonow RA et al: ACCIAHA guidelines. JAm Coll Cardiol 1998;
32:1486-1588,with permission.
compietion of theprocedure. Anticoagulation with warfarin is usu
ally begun about3weeks in advanceof cardioversionand for4weeks
afterthe procedure. Altematively, if left atrial thrombus is excluded
by TEE,2 to 3days of intravenous heparin should be instituted, the
palient cardiovertedto sinus rhythm,and warfarin therapy continued
foratleast 4 weeks. Patients with chronic atrial fibrillation and those
with a previous historyof embolism should receive anticoagulation
with warfarin (International Normalized Ratio (INR) of2to 3]unless
here is a specific contraindication.Systemic embolization necessi
tates permanent anticoagulation.A singlesystemic embolic tpisode
is not an absolute indication for miralvalve surgery;embolican and
dooccurinpatients with mild mitral stenosis.
INTERVENTIONAL THERAPY
Unless there is a contraindication,surgery or catheterballoon com
missurotomy (CBC)should be recommended to an MS patient with
functional class III or IV symptoms. For younger patients with a
pliable, non-calcifiedvalve and without important mitral regurgita
tion, this means valve repair or CBC. The hemodynamic results of
surgicalcommissurotomy orCBC are excellent. Because ofthe low
morbidity and mortalityof CBC/valve repair, surgery is alsooffered
tothose patients when functionalclass II symptoms are present.The
results of successful commissurotomy are excellent; in experienced
and skilled centers, surgical mortality is less than l percent. Late
mortalityat 10 years is less than 5 percent, the thromboembolism
rate is 2 percentper year or less, and the reoperation rate ranges from
0.5 to 4.5 percent per year (Table 23-2).
For theolder patient with a stiff or calcified valve or when mod
eratemitralregurgitationis present,mitral valve replacement is usu
ally performed. Valve replacement carries a higher operative mortal
ity than does commissurotomy (up to 5 percent) and the morbidity
associated with prostheses.Hemodynamic results of mitral valve re
placement areoften not ideal (see also Chap. 26).Survivalat 10years
aftermitralvalve replacement forfunctionalclass III and IV patients
isbetterthan 60percent (Table 23-3).
Use of the double balloon technique or the Inoue balloon pro
duces immediate and 3-month hemodynamic and clinical results
comparable to those obtained by surgicalcommissurotomy.Themi
tral valve area increases from a mean of 1.0 to 2.0 cm'. There are
reductions of LA and PA pressures at rest and on exercise and an
increase of exercise capacity. The immediate results of CBC are
greatly influenced by the characteristics of the valve and its sup
porting apparatus, which are best determined by 2D echocardiog
raphy (transthoracicand/or transesophageal)(Table 23-4).Echocar
diographicscores ofhigher PA systolic pressure is present prior to the CBC.
MITRAL REGURGITATION
Definition, Etiology, and Pathology
Mitral regurgitation (MR)is characterized by an abnormal reversed
blood flow from the left ventricle (LV)to the left atrium (LA)due to
abnormalities in the mitral apparatus.
21:11 dom., 15 de fev. @.
 60 to
80mmHg)with NYHA functionalclass I to II
symptoms who are not considered candidates for
percutaneous balloon valvotomy or mitralvalve
repair Ila
*The committee recognizes that there may be variability in the measurement
of mitralvalve area and that the mean transmitral gradient, pulmonary artery
wedgepressure, and pulmonaryartery pressure at rest or during exercise should
also betaken intoconsideration.
SoURCE: Bonow RA et al: ACCIAHA guidelines. J Am Coll Cardiol 1998;
32:1486-1588,with permission.
on the normal structureand function of every part of the mitral
apparatus--that is, the leafiets, chordae tendineae, annulus, left
atrium,papillarymuscles, and LV myocardium surrounding the pap
illary muscles. There is a report of MR and AR with use of anorectic
drugs.
Pathophysiology
The abnormal coaptation of the mitral leaflets createsa regurgitant
orifice during systole.Thesystolic pressure gradient between the LV
and LA is the driving forceof the regurgitantfow, which results in a
regurgitantvolume. This regurgitantvolume representsa percentage
of the total ejection of the LV and may be expressed as the regur
gitantfraction.The regurgitantvolume creates a volume overload
by enterin� the LA in systoleand the LV in diastole. modifying LV
loading and function because it is additive to the systolic output of
the right ventricle.
21:12 dom., 15 de fev. A
50mmHg
at rest or 60mmHg with exercise) in the
absenceofleft atrial thrombus or moderate to
severe MR
3.Patients with NYHA functional c�ass II to IV
symptoms, moderateor severe MS (mitral valve
arearegurgitationin patients
withorganic MR.MR is oftenassociatedwith an early diastolic rum
ble duetothe increased mitral Alow in diastole even without mitral
stenosis. The S3 and diastolic rumble are low-pitched sounds and
may be difficult to detectwithout careful auscultationin the left lat
eral decubitus position.TheS3 increaseswith expiration.In ischemic
and/or functionalMR, S3 coresponds more often to restrictive LV
flling. An atrial gallop (S4) is heard mainly in MR of recent onset
and in ischemic and/or functionalMR in sinus rhythm.Midsystolic
clicks are markers of valve prolapse and are due to sudden tension
of the chordae (discussed later).
The hallmark of MR is the systolic murmur, most often holosys
tolic, including first and second heart sounds. Ifan opening snap or
S3 is mistakenly interpretedas S2,the murmurmay appear midsys
tolic. The murmuris of a high-pitched and blowing type but may be
harsh,especiallyin valve prolapse.The maximum intensity is usu
ally at the apex, and it may radiate to the axilla when the anterior
leaflet results in greaterregurgitation and to the left sternal border
when the posteriorleaflet results in greaterregurgitation. In posterior
leaflet prolapse, the jet is usually superiorlyand medially directed
and the murmur radiates toward the base of the heart. In anterior
leaflet prolapse,the murmurmay be heard in the back, in the neck,
and sometimes on the skull.Inthecases where themurmurradiatesto
the base, it may be difficult to distinguish from the murmur ofaortic
stenosisor obstructive cardiomyopathy: pharmacologic maneuvers
show that the murmur decreases with reduction of afterloador LV
size and increases with increase of afterload or LV size.Murmur
intensity does not increase with postextrasystolic beats because the
degree of MR is not increased(seeChap. 1).
Murmurs of shorter duration usually correspond to mild MR;
they may be mid- or late systolic in mitral valve prolapse or early
systolic in functional MR.
ELECTROCARDIOGRAM
Chronic MR produces LA or LV enlargement typically manifest by
increased amplitude of the P waves and QRS complex. If atrial fib
rillation is present, the LA enlargement is associated with coarse
fibrillatory waves. RV hypertrophy is uncommon. The electrocar
diogram, especially in acute MR, may be entirely normal. When
papillary muscle ischemia or infarction is the cause of MR,evidence
of inferior or posteriorinfarction (old or new) may be present.
CHEST ROENTGENOGRAM
In chronic severeMR,thechest x-ray shows LA andLV enlargement.
In rheumatic disease,the valve leaflets may be calcified; with. degen
erative disease,a calcified mitral annulus is often present! Acute
severe MR is usually associated with normal cardiac size and pul
monary edema.
Laboratory Tests
ECHOCARIOGRAPHY/DOPPLER
The echocardiogram is usually helpful in defining the etiology of
the MR (e.g.,Aail leaflets, severe prolapse, mitral annulus calcifica
tion, systolic anteriormotion of the anteriorleaflet, and endocardi
tis vegetation)and determining its consequences. The ccho/Doppler
technique provides an estimate of the severityof the regurgitation
by assessing the velocity. width, and length of the regurgitant jet.
Color-fow imaging demonstrates the originand direction of the jet.
Accordingly, the jet length,the ratio of the jet area to the left atrial
area. or more simply size of the jet area have been suggested as
go0d indicesof the severityof MR. Smalljets, such as those seen
in nomal subjects,consistentlycorrespond to mild regurgitations.
Color-fow imaging for defining regurgitant lesions has significant
limitations that are intrinsically related to the nature of regurgitant
jets. The extent of a jet is deternminedby its momentum and thus as
much by regurgitantvelocity as by regurgitantflow.Also, jets are
consrained by theLAand expand more in large atria. The eccentric
jets of valvular prolapse depend on the left atrial wall and tend to
underestimate regurgitation. Incontrast, the central jets of ischemic
and functional MR expand markedly in a large atrium and tend to
overestimate regurgitation. Transesophageal echocardiography usu
ally shows larger jets but does not eliminate these limitations of
color-flow imaging.Thepulmonary venous velocity profile is useful
to assessthe degree of regurgitation. Systolicreversal of flow in the
pulmonary veins is a strong argument forsevere MR.Several quan
titative methods have been used to measure parameters that reflect
the degree of MR;however,the reliability of these techniques for the
quantitative assessment of MR remains to be demonstrated.
CARDIAC CATHETERIZATION
AND ANGIOGRAPHY
Cardiac catheterizationis utilized to assesshemodynamic status, the
severityof MR,LVfunction,and coronary artery anatomy. It con
frmsthe diagnosis of MR as well.A large v wave in the pulmonary
capillary wedge pressure tracingssuggests MR but its absence does
not exclude MR.A bailoon flotation catheter, inserted at the bed
sideto determine oxygen saturationin the right heart chambers and
the presence or absence of the v wave in the pulmonary capillary
pressures,is helpful in establishingthe cause of a new systolic mur
mur that develops in a patient afteracute myocardial infarction. The
assessment of the degree of regurgitation can be obtained by LV
conrast angiography and can be qualitatively graded in three or four
grades on the basis of the degree and persistenceof opacification
of the LA. The assessment of LV function can be pertormed using
quantitative angiography. LV volumes aredetermined by the regurgi
tantvolume, durationof regurgitation, etiology of regurgitation, and
LVfunction.The most frequently utilized indices of LV function
are the end-systolicvolume and the LV ventricular ejectionfraction.
Both havebecn shown to be usefulprognostically. The hemodynamic
response to exercise(e.g., cardiacoutput,pulmonary artery pressure)
often help to determine the need for valve replacement in borderline
circumstances.
Regional wall motion abnormalities have been observed in pa
tients with MR even in the absence of coronary lesions. Selected
coronary angiography is at present the only technique for defining
the coronary artery anatomy.It is usuallyperformed in patients above
35 years of age or in those with angina or multiple risk factorsfor
coronary artery disease.
OTHER LABORATORY STUDIES
Radionuclide angiography can be used to estimate the LV end
diastolic and end-systolicvolumes aswell as the RV andLV ejection
fractions. The detection of exercise-inducedLV dysfunction is fre
quent; however, the significanceof such measurements on the long
term prognosis has not been analyzed in large series of patients. The
comparisonof the counts measured over the RV and LV allows the
calculationof the mitral valve regurgitant fraction. Exercise testing
is often useful for determining the patient's exercise capacity,par
ticularly in thosewho appearrelatively asymptomaticdespite severe
MR.
Natural History and Prognosis
Because ofthe qualitative and imprecise assessment of the degree
of regurgitation, the natural history of MR is poorly defined. Pa
tients with mild rheumatic MR appear to have a good prognosis.The
prognosis of patients with mitral valve prolapse and no or mild re
gurgitationis usually excellent. Some deaths may occur in patients
with murmurs of MR and more often when LV function is markedly
decreased.
The predictors of poor outcome in patients with MR who are
treated medically include severe symptoms (classesIII to IV) even
if the symptoms are transient,pulmonary hypertension, markedly
increased LV end-diastolicvolume, decreased cardiac output, and
reduced LV ejectionfraction. A comparison of the outcome of med
ically and surgicallytreated patients showS a trend in favor,pf the
surgical treatment,especiallyearly surgery,with a definite inprove
ment of outcome with surgery in patientswho havedecreased systolic
LV function.
Medical TreatmentPrevention of infective endocarditiswith use of antibiotics is neces
sary in patients with MR.Young patients with rheumatic MR should
receiverheumatic feverprophylaxis.In patients with AF, rate control
is achieved using digoxin and/or beta blockers,diltiazem,and amio
darone. Long-term maintenance of sinus rhythm after cardioversion
in patients with severe MR or enlarged LA is usually not possible
in those who are treated medically. Oral anticoagulation should be
used inpatientswith atrial fibrillation (INR2.0 to 3.0).
Afterload reduction decreases the amount of regurgitationnot
only by reducing the LV systolicpressure but also by decreasing
the effective regurgitantorifice area.Theacute utilization of sodium
nitroprussidein unstable patients with severe MR,especiallyin the
context ofmyocardial infarction, may be lifesaving in patients being
prepared for mitral valve surgery.Chronicafterloadreduction is more
controversial.Diuretic treatment is extremely usefulfor the control
of heart failureand for the chronic control of symptoms, especially
dyspnea.
Surgical Treatment
Mitral valve reconstructionfor MR is often possible. The frequency
with which valve repaircan be used in patients with MR varieswith
the experience of the operating team and the spectrum of under
lying valve disease: repair is more often feasiblein patients with
degenerative valve disease than in those with regurgitation caused
by rheumatic valvulitis orendocarditis.LV systolic function and late
survivalin general are better with mitral valve repair than with mitral
valve replacement because of the lesser decline or maintenance of
normal LV function when the chordae are preserved at the time of
surgery. Inpatients whose mitral valves cannot be repaired,mitral
valve replacement with chordal preservation is less likely to depress
LV function than mitralvalve replacement without preservationofthe
chordae tendineae.Patientswith severe symptoms due toMR should
be treated surgicallyeven if symptoms are markedly improved by
medical treatment (Table 23-5). Patients who are functionalclass I
or Ilbut with signs of overt LV dysfunction (LV ejection fraction
45 mm)should be treated sur
gically, particularly if they are candidates for valve repairor valve
replacement with chordal preservation.In patient� with severe MR
who have no or minimal symptoms and no signs of LV dysfunction,
surgery is a reasonable option when it is likely that the mitral valve
be repaired with chordal preservation.This pertains to patients
with alow operative risk of I to 2 percent and valvularlesionsthat
an be repairedasindicatedby echocardiography. IntraoperativeTEE
RECOMMENDATIONSFOR MITRAL VALVE SURGERY
IN NONISCHEMICSEVERE �TRAL REGURGITATION
Indication Class
1.Acute symptomatic MR in which repair is likely
2. Patients with NYHA functionalclass I, II, orV
symptoms, with normal LV function defined as
ejectionfraction> 0.60 and end-systolic
dimension 50 mmHg at rest or > 60mmHg
with exercise
7. Asymptomatic patients with ejection fraction0.50
to 0.60 and end-systolicdimension 0.60
and end-systolicdimension 45 to 55 mm
8.Patientswith severe LV dysfunction (ejection
fraction 55
mm) in whom chordal preservationis highly likely
9. Asymptomatic patients with chronic MR with
preserved LV function in whom mitral valve repair
is highly likely
10. Patients with MVP and preserved LV function who
have recurrentventricular arrhythmias despite
medical therapy
11.Asymptomatic patients with preserved LV funcion
in whom significant doubt about the feasibility of
repairexists
Ila
Ila
Ila
Ila
Ilb
Ib
III
*Thecommitlee recognizes that there may be variability in the measurementofmitral
valve area and that the mean transmitral gradient, pulmonary artery wedge pressure
and pulmonary artery pressure at rest or during exercise should also be aken into
consideration.
SoURCE:Bonow RA et al: ACCIAHAguidelines. J Am CollCardiol1998;32:1486
I588,with permission.
448
should be performed by physicians to monitor the repair procedure
and help with decisions warranted by an imperfect result.
Patientswho have no symptoms due to severeMR and normal LV
systolic functionwho are candidates for mitral valve repair and have
severe pulmonary hypertension at rest or with exercise,atrial fibril
lation, or recurrentthromboemboli despite anticoagulationtherapy
arecommonly recommended forearly surgery if mitral valve repair
with preservationof the chordae is the likely procedure.
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