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Aetiology
- rheumatic heart disease
- infective endocarditis
- trauma: surgical or blunt chest trauma
- bicuspid aortic valve
- VSD
- dilatation of aortic ring: syphilis, seronegative arthritides eg ankylosing
spondylitis, Marfan’s, aortic dissection
- Coexisting aortic stenosis essentially limits possible aetiologies to
congenital and rheumatic. Aortic valve disease without mitral valve disease
less likely to be rheumatic
Haemodynamics
- associated with increased LV compliance and raised LVEDP (± > 40
mmHg)
- avoid bradycardia and increased SVR as both increase regurgitant flow and may
precipitate cardiac failure
- tachycardia and low aortic diastolic pressure result in decreased coronary
blood flow. Therefore the combination of ischaemic heart disease and AR
problematic
- impaired contractility with chronic volume overload and increased sensitivity
to myocardial depressants
- in severe cases relative inability to increase cardiac output resulting
intolerance of sepsis, arrythmias
Symptoms
- tend to occur late
- dyspnoea on exertion due to decreased forward flow
- orthopnoea, PND due to LVF
- angina, even without ischaemic heart disease
Signs
-
Pulse: collapsing, Corrigan’s, Quinke’s
-
BP: wide pulse pressure
-
JVP: usually normal
-
Thrills: ± diastolic +/or systolic. Latter does not necessarily indicate
AS
-
Apex beat: displaced, heaving
-
Heart sounds:
-
A2 usually diminished or absent in severe AR
-
Murmur:
-
early
diastolic
-
loudest at LSE or in aortic area (cases due to
aortic dilatation).
-
longer murmurs associated with more severe
AR
-
accentuated
by isometric exercise.
-
± aortic ejection flow murmur
-
± Austin-Flint murmur due to displacement of anterior cusp of mitral valve by
regurgitant jet. Soft, low pitched mid-diastolic or presystolic. Can be
differentiated from MS by absence of presystolic accentuation, loud HS1 and
opening snap
-
± functional MR due to LV dilatation
Investigations
- ECG. Severe cases: LV strain pattern. LAD and/or QRS prolongation suggest
diffuse myocardial disease, generally associated with patchy fibrosis, and
usually indicate a poor prognosis
- CXR: LV dilatation, pulmonary venous hypertension. In cases due to primary
valve disease may be dilatation of ascending aorta and knuckle. May be
aneurysmal dilatation of aorta in cases due to aortic dilatation
- Echo
- Angio
Treatment
Medical
- treat LVF along conventional lines. ACE inhibitors particularly
useful.
- nitrates can be used to treat angina but are less effective than in
ischaemic heart disease
Surgical
- aim to replace/repair valve when LV dysfunction occurs but
before patient becomes symptomatic
- AVR does not restore LV function to normal
- in patients with marked LV dysfunction surgical risk is higher but these
patients should still be offered AVR as the prognosis with medical treatment
alone is poor.
Epidemiology
Aetiology
-
congenital: may lead to stenosis as birth or aortic stenosis may develop in
later life due to haemodynamic stresses on congenital bicuspid valve
-
rheumatic heart disease
-
idiopathic valve calcification: rarely leads to significant aortic stenosis
Pathophysiology
- outflow obstruction results in relatively fixed stroke volume
- obstruction leads initially to LV hypertrophy and, if not relieved, to LV
failure and dilatation
- LV hypertrophy increases transmural pressure and decreases coronary perfusion
pressure
- LVH reduces compliance and therefore high LVEDP (and LAP) required. Atrial
contraction very important. Loss can lead to fall in CO of up to 40%. Vigourous
atrial contraction reflected in prominent ‘a’ wave in LAP
Haemodynamic problems
- LV hypertrophy and difficulty in oxygenating the subendocardium. The
vicious cycle that must be avoided is:
- high LV filling pressure
- decreased subendocardial perfusion pressure
- decreased subendocardial oxygen delivery
- subendocardial dysfunction
- decreased cardiac output
- decreased aortic and therefore coronary perfusion pressure
- further ischaemia
- dysrhythmias
- VF Once in VF these patients are very difficult to resuscitate.
- LV dysfunction
- stroke volume relatively fixed: falls in heart rate and in SVR believed to
be poorly
tolerated. In the case of the latter, a fall also reduces coronary perfusion
pressure which may result in a reduction of cardiac output. Small increase in
SVR can usually be tolerated provided LV function has not deteriorated.
- More recent data from small series of patients suggests that patients
may benefit from vasodilatation.
- tachycardia is also poorly tolerated because of the reduction in duration of
diastole
- important to maintain sinus rhythm
Symptoms
- exertional dyspnoea: result of raised pulmonary capillary pressure due to
raised LVEDP
- angina
- syncope: results from inability to raise cardiac output in the face of
peripheral vasodilatation or from arrhythmia
Signs
- Pulse:
- slow rising small volume pulse is characteristic
- in severe cases
slow rising character may be difficult to determine because of small volume
- bisferiens pulse virtually excludes pure aortic stenosis
- BP: usually normal but pulse pressure may be reduced in severe cases.
Marked systolic hypertension (eg >200) makes severe AS unlikely
- JVP: may be prominent ‘a" wave - LV hypertrophy results in limited
expansion of RV
- Thrills: may be present in aortic area and in neck
- In patients who do
not have obstructive airways disease, thick chest walls, thoracic deformity or
heart failure the absence of a thrill suggests that AS is mild
- Apex beat: not displaced until LV decompensation occurs
- Double impulse
may be palpable, especially with patient in left lateral position: atrial
contraction followed by ventricular contraction
- Auscultation:
- HS1 normal
- HS2 initially normal progressing through single
to reversed splitting due to delayed aortic valve closure
- ejection systolic murmu radiating to neck
and occasionally to apex
- HS4 in severe AS due to LVH and high LVEDP
- HS3 usually occurs with LVF
Investigations
- ECG: LVH and strain
- CXR: usually normal until late stages. LVH may result in rounding of
apex. On fluoroscopy (& echo) calcification of valve may be seen. In adults
absence of calcification excludes severe AS
Echo: thickening and calcification of cusps. Severity can be assessed
from estimated transvalvular gradient. In presence of normal cardiac output
gradient of ³ 50 mm Hg indicative of severe AS
- Cardiac catheter
Assessment
Clinical features of severe disease
- syncope
- angina
- low pulse pressure
- thrill
- LV dilatation
- delayed aortic valve closure
Investigations
- absence of valve calcification in adults suggests disease is not severe
- valve cross-sectional area < 0.5 cm2/m2 BSA
- transvalvular gradient. Important to take LV function into account
Management
Medical
- angina responds to nitrates
- previously thought that vasodilators are of little benefit in the
treatment of heart failure but recent evidence suggests that nitroprusside
infusion results in a rapid and marked improvement in cardiac function in
patients with severe aortic stenosis and severe LV systolic
dysfunction
- dose was titrated to reduce MAP to 60-70 mmHg
- patients in study had ejection fraction of 35% or less and aortic
valve cross sectional area of 1 cm2 or less
- resulted in increased stroke volume and cardiac index, decreased
pulmonary capillary wedge pressure, pulmonary and systemic vascular
resistance
- diuretics can be used cautiously in the treatment of heart failure but care
should be taken to avoid hypovolaemia
- regular follow-up to detect development of LV failure and dilatation
Surgical
- children and adolescents with severe non-calcific congenital AS benefit from
simple commissural incision even in absence of symptoms
- adults with severe AS and evidence of LV dysfunction or symptoms. Ideally
valve should be replaced before severe LV dysfunction occurs but the prognosis
of patients with the latter is so poor that valve replacement is still
indicated despite the high operative mortality (15%) and the risk of
persistent myocardial dysfunction
Further reading
Khot UN, Novaro GM, Popovic ZB et al. Nitroprusside in
critically ill patients with left ventricular dysfunction and aortic stenosis. N
Engl J Med 2003; 348:1756-63. A commentary on this paper can be found in Intensive
Care Monitor, 2003; 10(4):62-3
Aetiology
May be caused by disease of cusps, chordae tendinae, papillary muscles or
valve ring
- rheumatic fever
- subacute bacterial endocarditis
- trauma: blunt or penetrating injury or inaccurate mitral valvotomy
- LVF with resulting valve ring dilatation and functional MR
- MI resulting in papillary muscle rupture or dysfunction
- congenital
- ruptured chordae tendinae
Haemodynamics
- To and fro movement across valve
- regurgitant jet throughout systole
- forward flow through aorta decreased
- increased flow during diastole. LV rapidly distended until downward movement
of apex abruptly checked as valve cusps, chordae and papillary muscles drawn
tight. This sets up vibrations causing 3rd heart sound (there is some evidence
that this is not the mechanism by which 3rd HS produced) and as blood continues
to flow rapidly across taut cusps, a flow murmur
- Increased LA and pulmonary venous pressures
- large V wave during ventricular systole
- LAEDP similar to LVEDP as valve not obstructed. Mean LAP usually <LAP in
mitral stenosis
- LV dilatation and LVH
Acute MR
- acutely impaired LV function, pulmonary oedema and shock: insufficient time
for compensation by LV hypertrophy/dilatation and LA dilatation
Symptoms
- dyspnoea, orthopnoea, PND, haemoptysis, "bronchitis" (due to
pulmonary venous congestion)
- fatigue (low cardiac output)
- ankle oedema, hepatic pain, anorexia (secondary to RVF)
Examination
- mitral facies less common than in mitral stenosis because lower mean LAP
results in lower incidence of increased PVR and consequently low cardiac output
- pulse
- AF usual with severe MR
- Waveform normal or sharp (powerful LV
contraction)
- JVP: slightly increased. Considerable increase suggests RVF
- cardiac impulse: heave at apex beat
- apex beat: displaced
- auscultation
Investigations
ECG
- P mitrale (if in sinus rhythm)
- usually AF
- LVH
CXR
- LA and LV dilatation
- +/- LVF
Echo
- LV dilatation and hypertrophy
- LA dilatation
- failure of closure of valve
Cardiac catheter
- LV venticulogram allows approximate quantification of regurgitation into
mild (jet of contrast seen entering LA) and severe (marked opacification of LA)
- measurement of LAP not a guide to severity because of damping effect of LA
dilatation
Images
Complications
Treatment
Medical
Surgical
- indications: moderately disabled patients (ie dyspnoeic on normal
activity), particularly if cardiomegaly and increased LVEDV persist despite
medical treatment
- valve replacement associated with good immediate results. Complications
include: perioperative death, systemic emboli, SBE, peri-prosthetic
regurgitation. In patient with high SVR, valve replacement may precipitate LV
failure
Images
Epidemiology
- 4 times more common in females
- fully developed cases usually present >20 yrs
Aetiology
- 99% of cases due to rheumatic heart disease
- congenital: frequently associated with other lesions causing LV outflow
obstruction including AS, subaortic stenosis, coarctation
- other rare causes: calcified mitral valve ring, infective endocarditis
(bulky vegetations may cause obstruction to flow), granulomatous infiltration
in association with eosinophilia, SLE (treatment of Libman-Sachs endocarditis
with steroids may lead to significant fibrosis with development of MS
Haemodynamics
- raised LAP and hence PCP results in decreased pulmonary compliance,
pulmonary oedema and haemoptysis
- persistently raised LAP leads to reactive pulmonary hypertension. in late
stages RVF occurs. Further reduces forward flow. Also LV distorted by bulging
RV
- raised LAP results in LA dilatation and AF. Development of AF and loss of
atrial contraction results in a marked deterioration of haemodynamic function
and may lead to an exacerbation of pulmonary oedema. Pregnancy and infection
may also precipitate decompensation
- LV dysfunction occurs in 1/4 of patients with severe MS. May be result of
extension of scarring into myocardium and chronic reduction of preload
- low cardiac output in severe cases
Symptoms
- Due to pulmonary venous hypertension
- dyspnoea on exertion
- orthopnoea and paroxysmal nocturnal dyspnoea
- bronchitis
- haemoptysis
Signs
- General: malar flush, pinched and blue facies
- Pulse: normal/small amplitude, ± AF
- JVP: NAD
- Cardiac impulses: tapping impulse at apex, diastolic thrill at apex
frequent
- Auscultation:
- loud HS1
- ± loud P2
- opening snap (best heard at apex or
between apex and LSE, absent if valve calcified)
- low pitched diastolic murmur
starting immediately after the OS. Duration directly related to severity of MS.
Pre-systolic accentuation (except in AF).
- ± Graham Steele murmur (pulmonary
regurgitation 2° to pulmonary hypertension)
Investigations
ECG
- p mitrale (notched and > 0.12 sec)
- ± RVH 2° to pulmonary hypertension
CXR
- enlarged LA and LA appendage
- upper lobe blood diversion
- ± pulmonary oedema
Echo
Severity can be assessed on basis of valve cross-sectional area:
< 1 cm2 = severe
1 - 1.5 cm2 = moderate
1.5-2.5 cm2 = mild
Cardiac catheterization
Only necessary if diagnosis is in doubt or if patient thought to have
co-existent coronary artery disease
Complications
- AF in 40%. incidence with
age and size of LA
- systemic emboli: commonly recurrent, associated with AF and large LA
appendage. Occur in 20% of patients with MS at some time. 80% of these
patients are in AF at the time
- reactive pulmonary hypertension in 25% of patients with severe MS
- acute pulmonary oedema
- infective endocarditis
- bronchitis
- recurrent PE: important cause of morbidity and mortality in late stages.
Occur most frequently in patients with RVF
Management
Avoid:
- bradycardia: relatively fixed stroke volume
- tachycardia: reduces diastolic filling time and causes large increase in
LAP - may precipitate pulmonary oedema and reduce cardiac output
- hypovolaemia: reduces LAP and therefore ventricular filling (effect
magnified by stenosed valve)
- vasodilatation, for the same reasons
Medical
- prophylaxis against further attacks of rheumatic fever
- digoxin for AF
- diuretics for fluid retention (note that CXR and other changes due to
LAP do not respond to diuretics)
- prompt treatment of chest infections: often precipitate fluid retention so
diuretic should be considered at the same time
- prophylaxis against SBE
Surgical
Indications for surgery
- significant symptoms which limit normal activity
- pulmonary oedema without precipitating cause
- recurrent emboli
- pulmonary oedema in pregnancy (emergency valvotomy)
- deterioration due to AF which does not respond to medical treatment
- valve cross-sectional area <1.3 cm2 (valvotomy) or <1 cm2
if there is a possibility that valve replacement may be required
Surgical procedure
Valvotomy or replacement. Valve replacement leads to greatly increased LV
filling ± distension, with ensuing increase in LV
afterload
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