12. Síntomas y comorbilidades asociadas.
Estilos de vida.
Tratamiento para falla cardiaca = Sintomático
Calidad del seguimiento, efectividad de profilaxis si
requeridas.
Buscar TEV o sangrado en pacientes anticoagulados.
13. Examen físico importante en la detección de
pacientes asintomáticos.
Intensidad del soplo no se correlaciona
directamente con la severidad
Si prótesis, evaluar cambios en soplo o
sonidos de las válvulas.
EKG – Rx de tórax
25. Otros exámenes no invasivos
Prueba Utilidad
EKG con Ocurrencia objetiva de síntomas
ejercicio Estratificación de riesgo en EA
Ecocardiografía Información adicional en estudio de disnea
con ejercicio * ↑ grado de regurgitación mitral, gradiente aórtico
y P pulmonar
Impacto pronóstico en EA e IM
IM transitoria isquémica
Ecocardiografía Test de reserva contráctil
de estrés con Evaluación de severidad y estratificación de riesgo
dobutamina qx en EA con FEVI ↓ y gradiente ↓
RMN cardiaca Ecocardio de calidad inadecuada o inconsistente
De elección para evaluar volúmenes y función del
VD
26. Prueba Utilidad
Tomografía Evaluar severidad especialmente en EA
Abordaje prequirúrgico en EA de alto riesgo
considerados para TAVI
Fluoroscopia Calcificación valvular o del anillo
Movimiento de oclusores en válvulas mecánicas
Angiografía por Evaluación confiable y reproducible de FEVI en
radionúclidos pacientes en ritmo sinusal
* Pacientes asintomáticos con IM
Biomarcadores BNP relacionado con clase funcional y pronóstico
particularmente en EA e IM
Uso limitado hasta ahora
27.
28.
29. Estratificación de riesgo
EuroSCORE (European System for Cardiac Operative Risk
Evaluation; www.euroscore.org/calc.html)
STS (Society of Thoracic Surgeons) score
(http://209.220.160.181/STSWebRiskCalc261/)
30.
31. Ocurre en 25% de los pacientes con enfermedad
valvular crónica.
~ 80% de los pacientes adultos con EA
sintomática son hombres.
3 causas primarias: Calcificación de válvula
bicuspide, en tricuspide deteriorada y por
enfermedad reumática.
32.
33. Fisiopatología
Proceso gradual que resulta en cambios
adaptativos.
La P sistólica ↑ en el ventrículo lleva a hipertrofia.
↓ de la distensibilidad ventricular con ↑ en las
presiones de llenado.
Disfunción diastólica.
Desarrollo de síntomas previo a disfunción
ventricular.
34.
35. EA severa poco probable si el flujo
transvalvular es normal y hay un gradiente
de presión <40mmHg.
EA aórtica de bajo flujo-bajo volumen
EA pseudosevera vs. severa
Ecocardiografía con dobutamina
(menos de0.2 cm ,1 cm ) con + area, pero, significativo + del
2
gradiente, ayor de 40 mmHg), mientras que la pseudo-severe AS
muestra incrementa muestra ++ aumento en le tamaño de la
valvula sin cambios del gradiente.
Ecocardio con ejercicio puede dar datos pronósticos.
Contraindicada en EA sintomática
41. Cirugía
El RVA es la terapia definitiva.
Mortalidad de 1-3% en < 70 años y 4-8% en adultos
mayores seleccionados.
Riesgo quirúrgico mayor:
Edad,
comorbilidades, mujeres, clase funcional, cx de
emergencia, disfunción VI, HTP, EAC, cx previa
Riesgo de mortalidad tardía:
Edad,comorbilidades, síntomas severos, disfunción VI,
EAC no tratada, arritmias ventriculares
42.
43.
44.
45. Terapia médica
La progresión de la EA es un proceso activo.
Las estatinas no afectan la progresión.
Modificación de factores de riesgo de aterosclerosis.
NINGUNA terapia médica es capaz de mejorar los
desenlaces.
Diuréticos, digoxina, IECAS/ARA2 en pacientes con
síntomas de falla cardiaca.
Manejo de HTA evitando hipotensión.
46. Seguimiento
EA severa asintomática
Reevaluaral menos cada 6 meses con ecocardio.
Puede considerarse medición de BNP.
EA leve-moderada
En presencia de calcificaciones significativas
reevaluar anualmente.
Sin joven y sin calcificaciones importantes
evaluar cada 2-3 años.
47.
48. Puede ser causada por enfermedad primaria de las
valvas de la válvula y/o anormalidades en la
geometría de la raíz aórtica.
Países desarrollados aorta bicúspide y
enfermedades de la aorta ascendente.
Entre las demás causas de la crónica está la fiebre
reumática, y en la aguda la endocarditis.
Afectación del anillo:
Crónica: Anulectasia aórtica (característica del síndrome
de Marfán),
Aguda: Disección aórtica.
49. Signos clínicos: pulsaciones arteriales
exageradas y baja presión diastólica.
En la Ecocardiografía:
Vena contracta y el flujo retrogrado en la
diastole en la aorta descendente.
Medir la aorta en 4 niveles:
Anillo
Senos de valsalva
Union sinotubular*
Aorta ascendente
50. Fisiopatología
Todas las formas de IA producen una anormalidad
hemodinámica similar.
↑ Volumen diastólico final y estrés de la pared
Hipertrofia compensadora
Hipertrofia + dilatación ↑ volumen latido
Inicialmente se mantiene el Q
Dilatación Disfunción ventricular
51.
52.
53.
54.
55.
56. Historia Natural
IA aguda e IA crónica y sintomática Pobre
pronóstico sin intervención.
Una vez aparecen síntomas la mortalidad es
10-20% por año sin cx
Diámetro de fin de diástole del VI >50mm
Probabilidad de muerte o síntomas de
disfunción ventricular es 19% por año.
Marfan Diámetro y la historia familiar son
predictores de muerte/complicaciones
57. Mortalidad baja de 1-4% para cx aislada de
VA. ↑ con edad avanzada, FEVI ↓, necesidad
de CABG (3-7%)
Mayores predictores de mortalidad:
Edad avanzada, clase funcional mayor, FEVI
<50%, LVESD >50mm
Cx de raíz de aorta con reimplantación de
coronarias tiene mortalidad ligeramente
mayor
Mortalidad aumenta en procedimientos de
emergencia
58. Tratamiento médico
Vasodilatadores e inotrópicos
Corto plazo para mejorar las condiciones previo a
la cirugía.
En IA crónica y FC en presencia de HTA, cuando
cx está contraindicada o persiste disfunción POP.
Síndrome de Marfan
Betabloqueadores pueden enlentecer la dilatación
aórtica y ↓ el riesgo de complicaciones.
ARA2
Evitar actividad física agotadora, deportes de
contacto/competitivos/isométricos
59. Segunda valvulopatía más común en países
desarrollados.
Aguda Endocarditis, ruptura de músculo
papilar, trauma, ruptura de cuerdas
tendinosas
Crónica Mixomatosa, FR, endocarditis,
calcificación anular, congénita, CMD…
60. Es característica la dilatación de la AI y el
VI, con congestión pulmonar.
Congestión retrógrada + bajo gasto
anterógrado.
Es la valvulopatía con deterioro más
temprano de la función ventricular.
61. Todas las etiologías en que lesiones intrínsecas
afectan uno o más de los 5 componentes
funcionales de la válvula
La más común es la IM degenerativa
Papel importante de fiebre reumática en países
en desarrollo.
Aguda vs. crónica
62. Evaluación
IM Aguda
Sospechar ruptura de músc. papilares Edema
pulmonar o shock luego de IAM
Soplo decrescendo protosistólico suave o
inaudible.
Ecocardio urgente Función hiperdinámica +
FC
Endocarditis infecciosa o trauma
IM Crónica
Soplo holosistólico, más prominente en ápex e
irradiado a axila, al menos III/VI, S3
64. ETE en planeación quirúrgica.
Determinación de capacidad funcional.
Estudios sugieren que niveles elevados de BNP son
predictores de desenlaces:
≥105pg/ml Diferenciar pacientes asintomáticos a
riesgo de FC, disfunción del VI o muerte en el mediano
plazo.
Valor predictivo negativo.
65. Historia
Natural
La IM aguda es mal tolerada y tiene pobre
pronóstico en ausencia de intervención.
En ruptura tendinosa la condición puede
estabilizarse pero puede llevar a HTP.
En IM severa crónica asintomática a 5 años:
Muerte de cualquier causa 22 ± 3%
Muerte por causa cardiaca 14 ± 3%
Eventos cardiacos 33 ± 3%
Pobre pronóstico: Edad, FA, severidad, HTP,
dilatación AI, FEVI bajo, LVESD alto
66. Cirugía
Reparación es el tto óptimo siempre que sea
posible.
Menor mortalidad perioperatoria, mayor sobrevida,
mejor preservación POP de función del VI, menor
morbilidad a largo plazo.
Predictores de resultados POP:
Edad, FA, función VI preoperatoria, HTP,
reparabilidad de la válvula.
Mejores resultados cuando FE >60%
Reparación percutánea borde a borde: éxito 75%
67.
68.
69. Terapia
Médica
IM aguda
Nitratos y diuréticos pueden ↓ presiones de
llenado.
Nitroprusiato de sodio ↓ reduce la posgarga y
fracción de regurgitación, así como el balón de
contrapulsación.
Inotrópicos y balón en caso de hipotensión.
IM crónica
IECAS, betabloqueadores y espironolactona si hay
falla cardiaca.
70. Seguimiento
Asintomático + IM moderada + función VI
preservada
Seguimiento anual, ecocardio cada 2 años
Seguimientos más corto si los valores son
cercanos al punto de corte o hay cambios
significativos desde la última revisión
71. También llamada «IM funcional»
Las valvas y cuerdas son estructuralmente
normales.
La IM resulta de distorsión geométrica del
aparato subvalvular
Crecimiento del VI y remodelamiento debido a CM
idiopática o EAC
72. Evaluación
El soplo frecuentemente es suave y la intensidad
no se correlaciona con la severidad.
La IM isquémica es una condición dinámica
Ecocardio de estrés
↑ ≥13mm2 en EROA RR de muerte y hospitalización por
descompensación cardiaca
Se debe buscar y evaluar severidad después de IAM
Menores umbrales de severidad
Evaluación de estado coronario y viabilidad
miocárdica (si FE ↓)
73. Historia
Natural
IM isquémica crónica tiene pobre pronóstico.
↑ en la severidad
La presencia de EAC y disfunción sistólica son
factores pronósticos.
Datos más limitados en pacientes con IM
secundaria de etiología no isquémica.
74. Cirugía
Mortalidad operatoria es > que en IM primaria y
el pronóstico a largo plazo peor.
IM isquémica
Indicaciones y procedimiento qx preferido son
controversiales.
Persistencia y alta tasa de recurrencia después de
reparación
Ausencia de evidencia que la cx prolongue la vida
Presencia de viabilidad miocárdica es predictor de
buen pronóstico (+CABG)
75. Cuando está indicada la cx hay tendencia hacia la
reparación con anuloplastia con anillo protésico
rígido de tamaño reducido
Menor riesgo operatorio pero mayor recurrencia
No hay estudios aleatorizados comparando
reparación vs. reemplazo
Reparación percutánea borde a borde
76.
77. Tratamiento
médico
Tratamiento médico óptimo es
mandatorio
IECAS y betabloqueadores más
antagonista de aldosterona en
presencia de falla.
Diuréticos si sobrecarga de volumen.
Los nitratos pueden ser útiles en el tto
de la disnea aguda.
Indicaciones de terapia de
resincronización de acuerdo a guías.
78. La fiebre reumática es la principal causa.
Otras etiologías menos comunes:
EM congénita, cor trioatriatum, calcificación
anular mitral, LES, AR, mixoma de la AI,
endocarditis infecciosa con grandes
vegetaciones.
EM pura o predominante ocurre en aprox.
40% de todos los pacientes con enf. cardiaca
reumática.
79. El adultos normales el orificio valvular es 4-6cm2.
Cuando <2cm2, la sangre puede pasar de la AI al VI solo
propulsada por un gradiente de presión AV elevado.
Gasto cardiaco se mantiene en reposo pero ↑ poco con el
ejercicio
Cuando< 1cm2, se requiere una P de ~25mmHg en la AI
para mantener el gasto cardiaco normal.
Gasto cardiaco se subnormal en reposo y puede ↓ con el
ejercicio
80. Evaluación
Auscultatoriamente lo característico es
primer ruido fuerte, chasquido de apertura
después del segundo ruido y soplo diastólico,
que a veces puede no ser perceptible.
Hipertensión pulmonar severa
Soplo pansistólico por IT funcional en el borde
esternal izquierdo.
Soplo de Graham Steel de IP
81. El dx usualmente se establece mediante examen físico,
rx de tórax, EKG y ecocardiografía.
Evaluación exhaustiva de la morfología valvular para
planeación qx.
ETE en casos especiales
Pruebas con estrés
82. Historia
Natural
La sobrevida en pacientes asintomáticos es
usualmente buena hasta 10 años.
La progresión es altamente variable con
deterioro súbito, precipitado por embarazo,
FA o embolia.
Los pacientes sintomáticos tienen pobre
pronóstico sin intervención.
83. Intervención
Comisurotomía percutánea
Selección de los pacientes y experiencia del operador
Resultados iniciales buenos (área valvular >1,5cm 2 sin IM > 2/4) en
80% de los casos.
Complicaciones mayores: mortalidad (0,5-4%), hemopericardio
(0,5-10%), embolia (0,5-5%), IM severa (2-10%).
Eficacia: 30-70% después de 10-20 años
Deterioro funcional es tardío Reestenosis
84. Cirugía
Comisurotomía cerrada vs. abierta
Resultados buenos a largo plazo
Tasa de reoperación para reemplazo valvular de 0-7% a
36-53 meses y sobrevida a 10 años de 81-90%
Actualmente la cirugía es en su mayoría de reemplazo
valvular
Mortalidad 3-10%
Mortalidad a largo plazo relacionada con edad, clase
funcional, FA, HTP, función ventricular preqx, complicaciones
asociadas a la válvula
85.
86.
87. Terapia
médica
Diuréticos y nitratos de larga acción mejoran
transitoriamente la disnea.
Betabloqueadores o calcio-antagonistas no
dihidropiridínicos pueden mejorar la tolerancia al
ejercicio.
Anticoagulación
Enpacientes con FA
Enritmo sinusal: Embolia previa, o presencia de trombo en
aurícula izquierda (IC).
Considerarse cuando ETE muestra contraste espontáneo denso en
una AI grande (D >50mm o V >60ml/min) (IIaC)
Antiagregación no es una opción válida
88. Seguimiento
EM significativa asintomática sin intervención
Anual clínica y ecocardiográficamente.
Si menos severa, cada 2-3 años
Después de CMP exitosa el seguimiento es
igual al de pacientes asintomáticos.
Si fracasa y los síntomas persisten se debe
considerar cirugía (a menos que haya
contraindicaciones)
89. Poblaciones Especiales
Reestenosis sintomática tras cirugía o CMP
Reemplazo valvular en la mayoría de los casos
Nueva CMP Características favorables y mecanismo
predominante refusión comisural. CMP inicial exitosa, recaída
tardía.
CMP paliativa
IM severa + enf. valvular aórtica severa Cirugía
IM severa + enf. valvular aórtica moderada CMP*
+ IT severa + ritmo sinusal + crecimiento moderado auricular
+ IT funcional secundaria a HTP CMP
Cirugía Origen no reumático con fusión comisural ausente
Notas del editor
Stress testing Stress testing is considered here for the evaluation of VHD and/or its consequences, but not for the diagnosis of associated CAD. Predictive values of functional tests used for the diagnosis of CAD may not apply in the presence of VHD and are generally not used in this setting.20 Exercise ECG The primary purpose of exercise testing is to unmask the objective occurrence of symptoms in patients who claim to be asymptomatic or have doubtful symptoms. Exercise testing has an additional value for risk stratification in AS. Exercise testing will also determine the level of authorised physical activity, including participation in sports. Exercise echocardiography Exercise echocardiography may provide additional information in order to better identify the cardiac origin of dyspnoea—which is a rather unspecific symptom—by showing, for example, an increase in the degree of mitral regurgitation/aortic gradient and in systolic pulmonary pressures. It has a diagnostic value in transient ischaemic MR, which may be overlooked in investigations at rest. The prognostic impact of exercise echocardiography has been mainly shown for AS and MR. However, this technique is not widely accessible, could be technically demanding, and requires specific expertise. Other stress tests The search for flow reserve (also called contractile reserve) using low-dose dobutamine stress echocardiography is useful for assessing severity and operative risk stratification in AS with impaired LV function and low gradient.22 3.1.3.2 Cardiac magnetic resonance In patients with inadequate echocardiographic quality or discrepant results, cardiac magnetic resonance (CMR) should be used to assess the severity of valvular lesions—particularly regurgitant lesions—and to assess ventricular volumes and systolic function, as CMR assesses these parameters with higher reproducibility than echocardiography.23 CMR is the reference method for the evaluation of RV volumes and function and is therefore useful to evaluate the consequences of tricuspid regurgitation (TR). In practice, the routine use of CMR is limited because of its limited availability, compared with echocardiography.
MR may result from an abnormality or disease process that affects any one or more of the five functional components of the mitral valve apparatus (leaflets, annulus, chordae tendineae, papillary muscles, and subjacent myocardium) Acute Endocarditis Papillary muscle rupture (post-MI) Trauma Chordal rupture/leaflet flail (MVP, IE) Chronic Myxomatous (MVP) Rheumatic fever Endocarditis (healed) Mitral annular calcification Congenital (cleft, AV canal) HOCM with SAM Ischemic (LV remodeling) Dilated cardiomyopathy Radiation
age, AF, severity of MR (particularly EROA), pulmonary hypertension, LA dilatation, increased LVESD, and low LVEF.
Despite the absence of a randomized comparison between the results of valve replacement and repair, it is widely accepted that, when feasible, valve repair is the optimal surgical treatment in patients with severe MR. When compared with valve replacement, repair has a lower perioperative mortality, improved survival, better preservation of postoperative LV function, and lower long-term morbidity (Table 7). Beside symptoms, the most important predictors of postoperative outcome are: age, AF, preoperative LV function, pulmonary hypertension, and repairability of the valve. The best results of surgery are observed in patients with a preoperative EF .60%. While a cut-off of 45 mm has previously been generally accepted, in MR due to flail leaflet, LVESD ≥40 mm (≥22 mm/m2 BSA) has been shown to be independently associated with increased mortality with medical treatment, as opposed to mitral surgery.131 In addition to the initial measurements, the temporal changes of LV dimensions and systolic function should also be taken into account when making decisions about the timing of surgery, but these require further validation.
6.1.6 Medical therapy In acute MR, reduction of filling pressures can be obtained with nitrates and diuretics. Sodium nitroprusside reduces afterload and regurgitant fraction, as does an intra-aortic balloon pump. Inotropic agents and intra-aortic balloon pump should be added in case of hypotension. There is no evidence to support the use of vasodilators, including ACE inhibitors, in chronic MR without HF and they are therefore not recommended in this group of patients. However, when HF has developed, ACE inhibitors are beneficial and should be considered in patients with advanced MR and severe symptoms, who are not suitable for surgery or when there are still residual symptoms following surgery. Beta-blockers and spironolactone should also be considered as appropriate.13
6.1.7 Serial testing Asymptomatic patients with moderate MR and preserved LV function can be followed up on a yearly basis and echocardiography should be performed every 2 years. Asymptomatic patients with severe MR and preserved LV function should be seen every 6 months and echocardiography performed annually. The followup is shorter if no previous evaluation is available and in patients with values close to the cut-off limits or demonstrating significant changes since their last review. Patients should be instructed to report any change in functional status in a prompt manner.
In secondary MR or, as it is also termed, ‘functional MR’, valve leaflets and chordae are structurally normal and MR results from geometrical distortion of the subvalvular apparatus, secondary to LV enlargement and remodelling due to idiopathic cardiomyopathy or CAD. Thus, secondary MR is not a primary valve disease but results from tethering (apical and lateral papillary muscle displacement, annular dilatation) and reduced closing forces, due to LV dysfunction (reduced contractility and/or LV dysynchrony).12,17
An exercise-induced increase of ≥13 mm2 of the EROA has been shown to be associated with a large increase in the relative risk of death and hospitalization for cardiac decompensation.
Surgery for secondary MR remains a challenge. Operative mortality is higher than in primary MR and the long-term prognosis is worse due—at least in part—to the more severe comorbidities (Table 7). In ischaemic MR patients, indications and the preferred surgical procedure remain controversial, mainly because of the persistence and high recurrence rate of MR after valve repair and the absence of evidence that surgery prolongs life.146 Most studies show that severe ischaemic MR is not usually improved by revascularization alone, and that persistence of residual MR carries an increased mortality risk. The impact of valve surgery on survival remains unclear, since there are no randomized trials and the few observational studies addressing this issue have too many limitations to draw definite conclusions.147 Regarding prognosis, most studies failed to demonstrate improved long-term clinical outcome following surgical correction of secondary MR.148,149 The sole randomized trial, comparing CABG vs. CABG + valve repair in patients with moderate MR, was not designed to analyse the effect on survival of the addition of repair to CABG. It showed that the performance of valve repair improved functional class, EF, and LV diameter in the short-term. Numerous preoperative predictors of recurrent secondary MR after undersized annuloplasty have been identified and are indicative of severe tethering, and associated with a worse prognosis [LVEDD >65 mm, posterior mitral leaflet angle >45, distal anterior mitral leaflet angle >25, systolic tenting area >2.5 cm2, coaptation distance (distance between the annular plane and the coaptation point) >10 mm, end-systolic interpapillary muscle distance >20 mm, and systolic sphericity index <0.7].152 The prognostic value of these parameters should, however, be further validated. After surgery, localized alteration of geometry and function in the vicinity of papillary muscles is associated with recurrent MR.
The percutaneous mitral clip procedure may be considered in patients with symptomatic severe secondary MR despite optimal medical therapy (including CRT if indicated), who fulfil the echo criteria of eligibility, are judged inoperable or at high surgical risk by a team of cardiologists and cardiac surgeons, and who have a life expectancy greater than 1 year (recommendation class IIb, level of evidence C).
CABG ¼ coronary artery bypass grafting; CRT ¼ cardiac resynchronization therapy; LVEF ¼ left ventricular ejection fraction; MR ¼ mitral regurgitation; SPAP ¼ systolic pulmonary artery pressure. aClass of recommendation. bLevel of evidence. cThe thresholds for severity (EROA ≥20 mm2; R Vol .30 ml) differ from that of primary MR and are based on the prognostic value of these thresholds to predict poor outcome: see Table 5.17 dWhen exercise echocardiography is feasible, the development of dyspnoea and increased severity of MR associated with pulmonary hypertension are further incentives to surgery. There is continuing debate regarding the management of moderate ischaemic MR in patients undergoing CABG. In such cases, valve repair is preferable. In patients with low EF, mitral valve surgery is more likely to be considered if myocardial viability is present and if comorbidity is low. In patients capable of exercising, exercise echocardiography should be considered whenever possible. Exercise-induced dyspnoea and a large increase in MR severity and systolic pulmonary artery pressure favour combined surgery. There are no data to support surgical correction of mild MR.
Optimal medical therapy is mandatory: it should be the first step in the management of all patients with secondary MR and should be given in line with the guidelines on the management of HF.13 This includes ACE inhibitors and beta-blockers, with the addition of an aldosterone antagonist in the presence of HF. A diuretic is required in the presence of fluid overload. Nitrates may be useful for treating acute dyspnoea, secondary to a large dynamic component. The indications for resynchronization therapy should be in accordance with related guidelines.13 In responders, CRT may immediately reduce MR severity through increased closing force and resynchronisation of papillary muscles.159 A further reduction in MR and its dynamic component can occur through a reduction in tethering force in relation to LV reverse remodelling. En quienes responden puede inmediatamente ↓ la severidad de la IM por aumento en la fuerza de cierre y resincronización de los músculos papilares
Rheumatic fever is the leading cause of mitral stenosis (MS) (Table 237-1) . Other less common etiologies of obstruction to left atrial outflow include congenital mitral valve stenosis, cor triatriatum, mitral annular calcification with extension onto the leaflets, systemic lupus erythematosus, rheumatoid arthritis, left atrial myxoma, and infective endocarditis with large vegetations. Pure or predominant MS occurs in approximately 40% of all patients with rheumatic heart disease and a history of rheumatic fever (Chap. 322). In other patients with rheumatic heart disease, lesser degrees of MS may accompany mitral regurgitation (MR) and aortic valve disease. With reductions in the incidence of acute rheumatic fever, particularly in temperate climates and developed countries, the incidence of MS has declined considerably over the past few decades. However, it remains a major problem in developing nations, especially in tropical and semitropical climates (see p. 1949). In rheumatic MS, the valve leaflets are diffusely thickened by fibrous tissue and/or calcific deposits. The mitral commissures fuse, the chordae tendineae fuse and shorten, the valvular cusps become rigid, and these changes, in turn, lead to narrowing at the apex of the funnel-shaped ("fish-mouth") valve. Although the initial insult to the mitral valve is rheumatic, the later changes may be a nonspecific process resulting from trauma to the valve caused by altered flow patterns due to the initial deformity. Calcification of the stenotic mitral valve immobilizes the leaflets and narrows the orifice further. Thrombus formation and arterial embolization may arise from the calcific valve itself, but in patients with atrial fibrillation (AF), thrombi arise more frequently from the dilated left atrium (LA), particularly from within the left atrial appendage.
In normal adults, the area of the mitral valve orifice is 4–6 cm 2 . In the presence of significant obstruction, i.e., when the orifice area is reduced to < ∼2 cm 2 , blood can flow from the LA to the left ventricle (LV) only if propelled by an abnormally elevated left atrioventricular pressure gradient, the hemodynamic hallmark of MS. When the mitral valve opening is reduced to <1 cm 2 , often referred to as "severe" MS, a LA pressure of ∼25 mmHg is required to maintain a normal cardiac output (CO). The elevated pulmonary venous and pulmonary arterial (PA) wedge pressures reduce pulmonary compliance, contributing to exertional dyspnea. The first bouts of dyspnea are usually precipitated by clinical events that increase the rate of blood flow across the mitral orifice, resulting in further elevation of the LA pressure (see below). To assess the severity of obstruction hemodynamically, both the transvalvular pressure gradient and the flow rate must be measured (Chap. 230). The latter depends not only on the CO but on the heart rate, as well. An increase in heart rate shortens diastole proportionately more than systole and diminishes the time available for flow across the mitral valve. Therefore, at any given level of CO, tachycardia, including that associated with rapid AF, augments the transvalvular pressure gradient and elevates further the LA pressure. Similar considerations apply to the pathophysiology of tricuspid stenosis. The LV diastolic pressure and ejection fraction (EF) are normal in isolated MS. In MS and sinus rhythm, the elevated LA and PA wedge pressures exhibit a prominent atrial contraction pattern ( a wave) and a gradual pressure decline after the v wave and mitral valve opening ( y descent). In severe MS and whenever pulmonary vascular resistance is significantly increased, the pulmonary arterial pressure (PAP) is elevated at rest and rises further during exercise, often causing secondary elevations of right ventricular (RV) end-diastolic pressure and volume.
A comprehensive assessment of valve morphology is important for the treatment strategy. Scoring systems have been developed to help assess suitability, taking into account valve thickening, mobility, calcification, subvalvular deformity, and commissural areas. TOE should be performed to exclude LA thrombus before PMC or after an embolic episode, if TTE provides suboptimal information on anatomy or, in selected cases, to guide the procedure. Stress testing is indicated in patients with no symptoms or symptoms equivocal or discordant with the severity of MS. Dobutamine or, preferably, exercise echocardiography may provide additional information by assessing changes in mitral gradient and pulmonary pressures.
Survival in asymptomatic patients is usually good up to 10 years, progression being highly variable with sudden deterioration, which is usually precipitated by pregnancy or complications such as AF or embolism.163 Symptomatic patients have a poor prognosis without intervention.12
Closed mitral commissurotomy is still performed in developing countries, but otherwise has largely been replaced by open mitral commissurotomy using cardiopulmonary bypass, which is also now seldom performed. In series from experienced centres, mostly including young patients, long-term results are good with a rate of reoperation for valve replacement of 0–7% at 36–53 months, and 10-year survival rates of 81–90%.171,172 In current practice, surgery for MS is mostly valve replacement (95%) as a result of increasingly elderly presentation and unfavourable valve characteristics for valve repair.1,34 Operative mortality for valve replacement ranges from 3–10% and correlates with age, functional class, pulmonary hypertension, and presence of CAD. Long-term survival is related to age, functional class, AF, pulmonary hypertension, preoperative LV/RV function, and prosthetic valve complications.12
NYHA ¼ New York Heart Association; PMC ¼ percutaneous mitral commissurotomy. dUnfavourable characteristics for percutaneous mitral commissurotomy can be defined by the presence of several of the following characteristics: – Clinical characteristics: old age, history of commissurotomy, NYHA class IV, permanent atrial fibrillation, severe pulmonary hypertension. – Anatomical characteristics: echo score >8, Cormier score 3 (calcification of mitral valve of any extent, as assessed by fluoroscopy), very small mitral valve area, severe tricuspid regurgitation.
CI = contraindication; MS = mitral stenosis; PMC = percutaneous mitral commissurotomy. aSee Table 14. bSurgical commissurotomy may be considered by experienced surgical teams or in patients with contraindications to percutaneous mitral commissurotomy
and should also be considered when TOE shows dense spontaneous echo contrast or an enlarged left atrium (M-mode diameter .50 mm or LA volume .60 ml/m2 (recommendation class IIa, level of evidence C).174 Aspirin and other antiplatelet agents are not valid alternatives.
Asymptomatic patients with clinically significant MS, who have not undergone intervention, should be followed up yearly by means of clinical and echocardiographic examinations and at longer intervals (2 to 3 years) in case of less severe stenosis. Management of patients after successful PMC is similar to that of asymptomatic patients. It should be more stringent if asymptomatic restenosis occurs. When PMC is not successful and symptoms persist, surgery should be considered early unless there are definite contraindications.
When restenosis with symptoms occurs after surgical commissurotomy or PMC, reintervention in most cases requires valve replacement. Re-PMC can be proposed in selected patients with favourable characteristics if the predominant mechanism is commissural refusion, and in cases with an initially successful PMC if restenosis occurs after several years. PMC may have a palliative role in patients who present with valve anatomy that is not ideal for PMC, but who are not surgical candidates.175,176 For information on MS during pregnancy see Section 13. In the elderly, when surgery is high risk or contraindicated but life expectancy is still acceptable, PMC is a useful option, even if only palliative. In patients with favourable anatomic characteristics, PMC can be attempted first, resorting to surgery if results are unsatisfactory. In other patients, surgery is preferable. In patients with severe MS combined with severe aortic valve disease, surgery is preferable. In cases with severe MS with moderate aortic valve disease, PMC can be performed as a means of postponing the surgical treatment of both valves. In patients with severe TR, PMC can be attempted in patients with sinus rhythm, moderate atrial enlargement, and functional TR secondary to pulmonary hypertension. In other cases surgery on both valves may be preferred.177 Degenerative mitral annular calcification may be observed in elderly patients, especially with renal failure, but it seldom creates severe MS requiring surgery. Valve replacement is the only option for the treatment of rare cases of severe MS of non- rheumatic origin where commissural fusion is absent.