Aortic Valvular Stenosis

From Anvita Health Wiki

Contents 1 Etiology 2 Epidemiology 3 Pathology 4 Genetics 5 Clinical-manifestations 6 Diagnostic-procedures 7 Radiology 8 Differential-diagnosis 9 Management 10 More General Terms 11 Additional Terms 12 Internet Database 13 References

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

• 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

Genetics

• associated with defects in Notch1

Clinical-manifestations

• symptoms:

• may be asymptomatic
• exertional angina (more common presenting symptom in younger patients)
• exertional < A21280>syncope</ A21280> (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
• usually harsh in nature
• intensity of murmur may decrease as stenosis increases in severity & cardiac output diminishes
• duration or length of murmur increases with severity
• murmur heard best at base

• may be heard best at apex in the elderly as a high- pitched, musical sound ( Gallavarian's phenomenon)

• radiation of murmur to carotid arteries
• murmur may increase with decreased heart rate
• murmur is mid-systolic at upper sternal region [4]

• systolic thrill at base
• diminished A2
• accentuated precordial thrust at apex
• paradoxical splitting of 2nd heart sound (S2) or absence of A2 &/or S2 with severe aortic stenosis

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

• exercise testing under carefully controlled conditions

• avoid in symptomatic patients [4]
• hypotensive response identifies candidates for immediate aortic valve replacement [4]

• 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
• coexisting aortic regurgitation results in over- estimation of aortic valve gradient by doppler
• underestimation of transvulvular gradient with LV dysfunction [4]

• aortic value area (normal 3-4 cm2)

• 1.5-2 cm2: mild
• 1-1.5 cm2: moderate

• < 1 cm2: severe

• calcified aortic valve leaflets
• left atrial enlargement common
• left ventricular hypertrophy
• restricted wall motion

• angiography ( cardiac catheterization)

• all patients > 35 years of age for whom surgical intervention is considered [4]
• right & left heart catheterization if echocardiogram fails to define severity of diagnosis or if clinical findings differ from those of echocardiogram
• identifies transvalvular gradient in the presence of LV dysfunction
• as needed to identify coronary artery disease ( CAD)

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 [4]

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

Management

• cardiovascular risk modification for elderly with degenerative-calcific aortic stenosis
• restriction of physical activity
• arrhythmias poorly tolerated; treat aggressively

• cardioversion for atrial fibrillation [4]

• 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 (recommended) [4]
• 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 [8]

• stress testing can precipitate symptoms & heart failure
• CPR unlikely to be sucessful; chest compressions generally insufficient to open stenotic aortic valve

• asymptomatic patients - doppler at 6-12 month intervals
• referral to cardiology for severe aortic stenosis
• antibiotic prophylaxis for bacterial endocarditis

• previously recommended [4]
• new guidelines do not recommend [8]
  

• Surgery:

• indicated in symptomatic patients, or patients with LV dysfunction or hypotension on exercise stress testing [4]
• aortic valve replacement for patients undergoing CABG [4]
• consider coronary artery bypass graft ( CABG) if significant coronary artery disease ( CAD) during aortic valve replacement ( AVR)
• 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 [4]

• aortic valve replacement
• Ross procedure - pulmonic valve autograft
• self-expanding, percutaneous aortic valve prosthesis [6] ( transcatheter aortic valve implantation, TAVI)
  

• Follow-up

• echocardiogram to assess aortic valve area [4]

• yearly for severe AS
• every 2 years for moderate AS
• every 5 years for mild AS

More General Terms

• valvular heart disease
• chronic heart disease

Additional Terms

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

Internet Database

OMIM: 109730

References

1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 126-28
2. DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 866
3. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 40-41
4. Medical Knowledge Self Assessment Program (MKSAP) 11, 14 American College of Physicians, Philadelphia 1998, 2006
5. Nkomo VT et al, Burden of valvular heart diseases: A population-based study. Lancet 2006, 368:1005 PMID: [1]
6. Grube E et al, Percutaneous implantation of the CoreValve self-expanding valve prosthesis in high-risk patients with aortic valve disease: The Spieburg First-in-Man Study. Circulation 2006, 114:1616 PMID: [2]
7. Wilson W et al, Prevention of infective endocardititis: guidelines from the American Heart Association Rheumatic Fever, Endocarditis and Kawasaki Disease Committe, Council on Cardiovascular Disease in the Young, and Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. J AM Dent Assoc 2008, 139:3S PMID: [3]
8. Geriatric Review Syllabus, 7th edition Parada JT et al (eds) American Geriatrics Society, 2010

aortic valvular stenosis (AS)