aortic valvular stenosis (AS)

Classification

• mild:
  • mean transvalvular pressure gradient < 25 mm Hg
  • Vmax across aortic valve < 3 m/sec
  • aortic valve area > 1.5 cm2
• moderate
  • mean transvalvular pressure gradient 25-40 mm Hg
  • Vmax across aortic valve 3-4 m/sec
  • aortic valve area 1.0-1.5 cm2
• severe
  • mean transvalvular pressure gradient > 40 mm Hg
  • Vmax across aortic valve > 4 m/sec
  • aortic valve area < 1.0 cm2

Etiology

• atherosclerosis
  • calcification & degeneration of a normal valve
  • most common cause of aortic stenosis in adults > 55 years
• congenitally bicuspid aortic valve
  • calcification & fibrosis
  • 1% of population
  • most common cause of aortic stenosis in adults < 55 years
  • ejection click often precedes murmur
• rheumatic valvular disease
  • uncommon cause
  • generally occurs 40-60 years of age
  • rheumatoid arthritis increases risk
• bacterial endocarditis

Epidemiology

• most patients present in 5th-7th decade of life
• 2.8% of elderly (> 75 years)

Pathology

• high pressure gradient from left ventricle to aorta
• concentric hypertrophy of left ventricle
• reduced left ventricular compliance
• increased left ventricular end diastolic pressure
• increased myocardial oxygen demand
• increased left ventricle wall stress
• decreased perfusion pressure across myocardium
• subendocardial ischemia
• infective endocarditis may complicate aortic stenosis
• disruption of HMW vWF multimers may occur
  • secondary von Willebrand's disease may occur
  • deficiency of von Willebrand factor is directly related to the severity of aortic stenosis as assessed by the transvalvular pressure gradient

Genetics

• associated with defects in Notch1
• genetic risk factors for elevated LDL cholesterol associated with aortic valve calcification & aortic valvular stenosis

Clinical manifestations

• symptoms:
  • may be asymptomatic
  • exertional angina (more common presenting symptom in younger patients)
  • exertional syncope (more common presenting symptom in younger patients)
  • heart failure (more common presenting symptom in older patients)
  • exertional dyspnea
• signs:
  • slowly rising & diminished carotid pulse that is sustained (pulsus parvus, pulsus tardus)
    • sign may be absent in elderly patients
  • systolic murmur
    • mid to late peaking (crescendo-decrescendo)
    • usually harsh in nature
      • may be softer in elderly
    • intensity of murmur may decrease as stenosis increases in severity & cardiac output diminishes
    • duration or length of murmur increases with severity
    • Valsalva maneuver diminishes the intensity of the murmur
    • murmur heard best at right upper sternal border
      • may be heard best at apex in the elderly as a high-pitched, musical sound (Gallavarian's phenomenon)
    • radiation of murmur to right clavicle, carotid artery
      • with severe aortic valvular stenosis, murmur may radiate down the descending thoracic aorta
    • murmur may increase with decreased heart rate
    • murmur is mid-systolic at upper sternal region
  • systolic thrill at base
  • diminished A2 with severe aortic valvular stenosis (AS)
    • most indicative sign of severe, rather than mild, aortic stenosis
  • weak & delayed carotid upstroke with severe AS
  • accentuated precordial thrust at apex
    • enlarged, nondisplaced & sustained apical impulse
  • paradoxical splitting of 2nd heart sound (S2) or absence of A2 &/or S2 with severe aortic stenosis
    • absence of A2 more common in elderly
  • S4 gallop due to atrial contraction into a noncompliant ventricle
  • non-calcified bicuspid aortic valve will have ejection click followed by systolic murmur

Laboratory

• troponin-I in serum/plasma may be elevated with severe aortic stenosis due to left ventricular wall stress & myocardial ischemia

Diagnostic procedures

• electrocardiogram
  • tall R waves
  • ST segment depression & inverted T-waves
    • leads I, aVL, V4-V6
  • left bundle branch block is common due to calcification of interventricular septum
  • Q waves suggest coexistent coronary artery disease (CAD)
  • left ventricular hypertrophy
  • often normal in young patients
• echocardiogram (Doppler)
  • aortic valve pressure gradient
    • > 50 mm Hg (mean) or > 80 mm Hg (peak) in severe AS
    • average annual increase of 8.3 mm Hg (peak) & 6.3 (mean) mm Hg in severe AS
    • coexisting aortic regurgitation results in over-estimation of aortic valve gradient by doppler
    • underestimation of transvalvular gradient with LV dysfunction
    • aortic gradient predicts prognosis better than estimated valve area
  • aortic value area (normal 3-4 cm2)
    • 1.5-2 cm2: mild
    • 1-1.5 cm2: moderate
• < 1 cm2: severe
  • peak aortic velocity (Vmax = 2-6 m/sec)
  • calcified aortic valve leaflets
  • left atrial enlargement common
  • left ventricular hypertrophy
  • restricted wall motion
  • frequency of serial evaluation
    • every 3-5 years
      • asymptomatic patients with mild AS
      • Vmax < 3 m/sec, gradient < 20 mm Hg
    • every 1-2 years
      • moderate AS, Vmax 3-4 m/sec, gradient 20-40 mm Hg
    • every 6-12 months every 6-12 months
      • asymtomatic severe AS preserved LVEF
      • aortic valve replacement not necessary
    • aortic valve replacement in symptomatic patients
• dobutamine echocardiography for low flow, low gradient aortic stenosis due to LV systolic dysfunction (low LVEF)
• exercise testing
  • not routinely indicated
  • reasonable in asymptomatic patients with severe aortic stenosis
    • consider prior to or in lieu of angiography
    • contraindicated in patients with severe aortic stenosis
      • apparently not contraindicated
  • perform under carefully controlled conditions
  • avoid in symptomatic patients
  • hypotensive response identifies candidates for immediate aortic valve replacement
  • resting & exercise serum BNP (asymptomatic, severe AS)
    • a marked increase in serum BNP during exercise predicts adverse events
• angiography (cardiac catheterization)*
  • all patients > 35 years of age for whom surgical intervention is considered
  • right & left heart catheterization if echocardiogram fails to define severity of diagnosis or if clinical findings differ from those of echocardiogram & patient is candidate for intervention
  • identifies transvalvular gradient in the presence of LV dysfunction
  • as needed to identify coronary artery disease (CAD)
  • severe aortic stenosis with worsening symptoms

* CT angiography or magnetic resonance angiography if bicuspid aortic valve & aortic root & ascending aorta not adequately visualized with echocardiography

Radiology

• chest X-ray
  • calcification of aortic valve ring
  • enlargement of left ventricle
  • prominent ascending aorta
  • aortic root may show post-stenotic dilatation
  • boot-shaped cardiac silhouette
• computed tomography measurement of valve calcification
  • useful for patients with discordant aortic valve area with aortic valve gradient
• CT angiography or magnetic resonance angiography if bicuspid aortic valve & aortic root & ascending aorta not adequately visualized with echocardiography

Complications

• Heyde syndrome in patients with gastrointestinal angioectasias
• patients with LV systolic dysfunction are at high risk for hospitalization for heart failure, death, or need for aortic valve replacement
• exertional syncope
  • younger patients
  • older patients with severe aortic stenosis
• myocardial fibrosis detected by cardiac magnetic resonance is associated with late mortality
• 5-year mortality rates for patients with mild, moderate,& severe AS is 34%, 43%, & 53%, respectively
• acquired von Willebrand syndrome
  • loss of HMW vWF multimers compromising platelet function
    • measure HMW vWF multimers
  • see Pathology: (above)

Differential diagnosis

• aortic sclerosis
  • no diminished A2
  • no diminished carotid pulses
• mitral regurgitation (holosystolic murmur at apex)
• pulmonic stenosis (ejection murmur loudest at left sternal border)
• hypertrophic obstructive cardiomyopathy
  • ejection murmur at left sternal border
  • prominent pulses with a bifid quality
• aortic pseudostenosis
  • low flow, low gradient aortic stenosis due to LV systolic dysfunction
    • dobutamine echocardiography distinguishes

Management

Medical management

• cardiovascular risk modification for elderly with degenerative-calcific aortic stenosis
  • smoking cessation
• restriction of physical activity
• arrhythmias poorly tolerated; treat aggressively
  • cardioversion for atrial fibrillation
• heart failure associated with AS
  • digoxin may be of benefit if left ventricular dilatation
  • diuretics
    • may be useful in treating congestive symptoms
    • reduction of left ventricular filling pressure may decrease cardiac output & systemic blood pressure
    • use with caution
  • ACE inhibitor or angiotensin receptor blocker (recommended)
  • avoid nitrates & other vasodilators
    • reduction of left ventricular filling pressure
    • decrease cardiac output & systemic blood pressure
    • hemodynamic collapse
  • use beta-blockers cautiously only for angina
• angina
  • nitroglycerin
  • hypotension from nitroglycerin
    • volume expansion
    • failure of volume expansion
      • inotropic agents (dobutamine)
      • vasopressors
  • use beta-blockers cautiously
  • coronary angiography if surgical candidate
    • stress testing can precipitate symptoms & heart failure
    • CPR unlikely to be sucessful; chest compressions generally insufficient to open stenotic aortic valve
• asymptomatic patients
  • clinical evaluation annually
  • optimal blood pressure unclear
    • systolic BP < 120 mm Hg, diastolic BP > 90 mm Hg, & pulse pressure < 50 mm Hg associated with higher all-cause mortality
    • average systolic BP 130-160 mm Hg associated with lowest all-cause mortality
  • echocardiogram (see classification above)
    • mild: every 3-5 years
    • moderate: every 1-2 years
    • severe: yearly
• onset of symptoms associated with expected survival of 2-3 years without surgical intervention
• referral to cardiology for severe aortic stenosis
• antibiotic prophylaxis for bacterial endocarditis
  • previously recommended
  • new guidelines do not recommend
• rosuvastatin does not slow progression of aortic stenosis

Surgery

• aortic valve replacement (AVR) indicated in
  • symptomatic patients
    • prolongs life in severe aortic stenosis
  • patients with LV dysfunction (LVEF < 50%) or hypotension on exercise stress testing
  • rapid progression of aortic stenosis
  • mean aortic value pressure gradient > 60 mm Hg
  • moderate or severe AS during cardiac surgery for other reason (CABG)
    • consider CABG in patients with CAD during AVR
  • asymptomatic patients with severe AS
    • class IIa recommendation for very severe AS
    • not indicated if preserved LVEF
      • asymptomatic patients with severe AS & preserved LVEF may benefit (see complications)
    • prognosis without aortic valve replacement is poor
    • hospitalizations for heart failure & death lower with AVR in patients with asymptomatic severe AS
• aortic valve replacement (AVR) procedures
  • Ross procedure - pulmonic valve autograft
  • self-expanding, percutaneous aortic valve prosthesis (transcatheter aortic valve implantation, TAVI)
    • indicated for patients with high surgical risk
    • tricuspid aortic valves only
    • symptomatic patients with severe aortic stenosis
    • patients without severe aortic regurgitation
    • similar 1-year outcomes with TAVR in bicuspid & tricuspid aortic valves
• intraaortic balloon counterpulsation may stabilize patients with critical aortic stenosis until surgery for AVR
• percutaneous balloon aortic valvuloplasty reserved for
  • congenital AS
  • patients for which surgery is not an option
  • 20% complication rate
  • high incidence of restenosis
  • not for adults with calcific AS

• non cardiac surgery
  • extensive preoperative testing unncessary in asymptomatic patients
  • intraoperative & postoperative hemodynamic monitoring
  • aortic valve replacement when indicated prior to elective non-cardiac surgery

Follow-up

• echocardiogram to assess aortic valve area
  • 6-12 months for severe AS*
  • every 2 years for moderate AS
  • every 3-5 years for mild AS

* higher mortality & hospitalization for heart failure & lower rates of aortic valve replacement (19% vs 54%) for nonadherent patients

More general terms

• chronic heart disease

More specific terms

• Heyde syndrome

Additional terms

• aortic subvalvular stenosis
• aortic supravalvular stenosis
• aortic valve
• aortic valve replacement (AVR)

Patient information

aortic stenosis patient information

Database

• OMIM: https://mirror.omim.org/entry/109730