AORTIC VALVULAR STENOSIS

AORTIC VALVULAR STENOSIS - Suzanne Klainer, MD
BASICS
DESCRIPTION
Acquired or congenital obstruction to left-ventricular outflow across aortic valve caused by decreased valve area. Is classified as mild, moderate, or severe based on measured area.
GENERAL PREVENTION
Prevention of Rheumatic Heart Disease for acquired postinflammatory aortic stenosis.
EPIDEMIOLOGY
• Predominant age (1)
- 30 years: Congenital
- 30-70 years: Congenital or rheumatic
- >70 years: Degenerative calcification of aortic valve
• Predominant sex: Male > Female, 2:1
Prevalence (2)
• 1.3% of 65-74 years
• 2.4% of 75-84 years
• 4% of >84 years
• Bicuspid aortic valve: 0.8% of population (3)
ALERT
Geriatric Considerations
Increased incidence of degenerative calcific aortic stenosis
RISK FACTORS
• Unicommissural valve
• Bicuspid valve
• Prior rheumatic fever
• Advanced age
• Hypercholesterolemia
• Metabolic disease (SLE, Fabry)
PATHOPHYSIOLOGY
Resistance to outflow at the aortic orifice causes increased afterload. The left ventricle responds to this pressure overload with thickening of myocardial wall, resulting in left ventricular (LV) dysfunction and CHF as well as increased myocardial oxygen demand.
ETIOLOGY
• Congenital
- Unicuspid valve
- Bicuspid valve: Not inherently stenotic, but becomes so as a result of wear-and-tear thickening and calcification; calcified bicuspid valve is most common cause of isolated aortic stenosis in adults.
- Tricuspid valve with fusion of commissures
- Hypoplastic annulus
• Acquired
- Rheumatic fever (or, rarely, other inflammatory disease)
- Degenerative calcific aortic stenosis in elderly
ASSOCIATED CONDITIONS
• Coronary artery disease (present in 50% of patients)
• Aortic regurgitation (particularly in calcified bicuspid valves and rheumatic disease)
• Mitral valve disease (primarily in rheumatic heart disease)
• LV dysfunction and CHF
• A-fibrillation associated with CHF


DIAGNOSIS
SIGNS AND SYMPTOMS
• Angina pectoris: Most frequent symptom
• Near syncope
• Syncope: Often exertional
• Exertional dyspnea
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Palpitations
• Fatigue
• Neurologic events (transient ischemic attack or cerebrovascular accident) owing to embolization
• Systolic crescendo-decrescendo murmur: Usually best heard at 2nd right sternal border (may have associated thrill); may radiate into carotid arteries
• Ejection (early systolic) click
• Prolonged ejection time
• Delayed, small carotid upstroke
• Delayed/decreased intensity of A2
• Paradoxical splitting of S2
• LV heave
• High-pitched diastolic blow: May be present at left sternal border (associated aortic regurgitation)
History
Above symptoms in elderly patient or one with history congenital heart defect or rheumatic fever
Physical Exam
• Cardiac
- Systolic crescendo-decrescendo murmur RSB, radiating to carotids
- Delayed carotid upstroke
- Left ventricular heave
- Increased intensity of A2
TESTS
ECG
• Conduction defects
• Left-atrial enlargement
• Ventricular arrhythmias
• LV hypertrophy
• ST segment depression
Lab
Elevated BNP
Imaging
• Chest radiograph
- May be normal in compensated, isolated valvular aortic stenosis
- Cardiac hypertrophy early, later cardiomegaly
- Poststenotic dilatation of ascending aorta
- Calcification of aortic valve cusps (may require fluoroscopy to visualize)
• Echocardiography
- Aortic valve morphology, thickening, calcifications
- Decreased aortic valve excursion
- Planimetry of aortic valve area
- LV hypertrophy
- LV ejection fraction
- Chamber dimensions
- Presence or absence of wall-motion abnormalities suggesting coronary artery disease
• Doppler echocardiography
- Transvalvular gradient
- Valve area
- Diastolic function
- Associated aortic regurgitation
Diagnostic Procedures/Surgery
Cardiac catheterization: Recommended for patients undergoing AV replacement at risk for CAD and for assessment of severity when AVR is planned or noninvasive studies are inconclusive (A)
• Identifies transvalvular gradient, valve area, LV ejection fraction, concomitant CAD
Pathological Findings
• LV hypertrophy
• Myocardial interstitial fibrosis
• Aortic valvular calcification in older patients
• 50% incidence of concomitant CAD
DIFFERENTIAL DIAGNOSIS
• Mitral regurgitation
- Either primary or secondary to underlying coronary artery disease or dilated cardiomyopathy
- Usually an apical, high-frequency, pansystolic murmur, often radiating to axilla
• Hypertrophic obstructive cardiomyopathy
- Also systolic crescendo-decrescendo murmur, but best heard at left sternal border and may radiate into axilla
- However, characteristically intensified by changing from squatting to standing and/or by Valsalva maneuver, lessened by changing from standing to squatting
• Aortic supravalvular stenosis
• Discrete subaortic stenosis
TREATMENT
STABILIZATION
Outpatient care except for surgical intervention or comorbid condition requiring hospital care
GENERAL MEASURES
• Asymptomatic patient with noncritical aortic stenosis: Because aortic stenosis is progressive, follow closely with appropriate evaluation.
• All patients should receive endocarditis prophylaxis prior to dental work or invasive procedures regardless of age, cause, or severity of stenosis. (4)[C]
• Patients with stenosis of rheumatic cause should receive (in addition to endocarditis prophylaxis prior to dental work or invasive procedures) rheumatic fever prophylaxis, especially if 35 years or in close contact with young children.
• Screen for and treat comorbid diseases.
- Commonly HTN, CAD, CHF, and A-fib.
ALERT
Pregnancy Considerations
• Severe critical aortic stenosis responds poorly to hemodynamic changes in pregnancy, labor, and delivery.
• Pregnancy should be avoided with critical aortic stenosis; may need Cesarean section for delivery of baby.
Diet
Only restriction is low-sodium diet in presence of CHF
Activity
In known or suspected severe aortic stenosis, vigorous physical activity contraindicated
MEDICATION (DRUGS)
• ACE I is beneficial for treatment of LV dysfunction and associated heart failure, but can cause hypotension in patients with baseline low blood pressure (5) [B].
• Statins: Anecdotal evidence suggest that statins slow progression of AS, however, recent RCT failed to support this claim (6).
• Prophylactic antibiotics for
- Bacterial endocarditis
- Rheumatic fever, where indicated
- See "General Measures"
ALERT
Use antihypertensives cautiously, because they potentially can cause hypotension in AS.
SURGERY
• Aortic valve replacement indicated in
- Patients with symptomatic severe AS, patients with severe AS undergoing CABG, or patients with severe AS undergoing aortic or other valve surgery (4)[A].
- Moderate AS undergoing cardiac surgery (4)[B]
- Asymptomatic patients with critical AS (aortic valve area 0.6.0 cm2), LV dysfunction, abnormal response to exercise, ventricular tachycardia, or increasing cardiomegaly (15 mm) (4)[C]
• Surgical valve replacement consists of removal of stenotic, native valve and placement of prosthetic mechanical or tissue valve.
• Balloon angioplasty of stenotic aortic valves
- May benefit pediatric patient with congenital disease (4)[A]
- In elderly as a bridge to AV replacement, for palliation in patients with serious comorbid conditions, and in patients who require urgent noncardiac surgery (4)[B]
FOLLOW-UP
DISPOSITION
Admission Criteria
See criteria for comorbid conditions.
Discharge Criteria
See criteria for comorbid diseases.
PROGNOSIS
• Mortality following onset of symptoms (7)
- 26% at 1 year
- 57% at 3 years
• Risk of sudden death is 0.4% per year (4)
COMPLICATIONS
• Progressive stenosis
• Sudden death
• Congestive heart failure
• Angina
• Syncope
• Hemolytic anemia
• Bleeding disorder (acquired vWF d/o) (8)
• Infective endocarditis
PATIENT MONITORING
• Symptomatic patients should be examined frequently.
• ECG every 2-5 years to assess progression in the asymptomatic patient with mild/moderate disease, respectively (4)[C]
• Advise patient to immediately report any symptoms referable to AS.
REFERENCES
1. Subramanian E. Surgical pathology of pure aortic stenosis. A study 374 cases. Mayo Clin Proc. 1984;59:683.
2. Stewart et al. Clinical factors associated with calcific aortic valve disease. J Am Coll Cardiol. 1997;29:630.
3. Otto CM, Burwash, Legget, et al. Prospective study of asymptomatic valvular aortic stenosis. Clinical, echocardiographic and exercise predictors of outcome. Circulation. 1997;95:2262.
4. Bono et al. ACC/AHA task force report. J Am Coll Cardiol 1998;32:1486.
5. Chockalingam et al. SCOPE-AS. Am Heart J. 2004;147(4):E19.
6. Crowell et al. SALTIRE. N Engl J Med. 2005;352:2389-2397.
7. Chizner et al. The natural history of aortic stenosis in adults. Am Heart J 1980;99(4):419-424.
8. Vincentelli, et al. Acquired von Willebrand in aortic stenosis. N Engl J Med. 2003;349:343.
9. Nistri, et al. Frequency of bicuspid aortic valves in young male conscripts by echocardiogram. Am J Cardiol. 2005;96:718.
MISCELLANEOUS
LV is relatively noncompliant in aortic stenosis, thus
• Atrial contraction is important component of diastolic filling.
• Loss of atrial contraction with onset of atrial fibrillation can cause acute clinical and hemodynamic deterioration.