Aortic stenosis may be congenital, such as in persons with a bicuspid aortic valve, or acquired. The most common cause is degeneration of the valve that occurs with aging: severe lesions occur in approximately 3% of persons aged 65 years and older. Other causes include rheumatic disease and chest radiation.
Pathophysiology of Aortic Stenosis
- It causes obstruction to LV outflow, which results in LVH.
- When the aortic valve area falls below 1 cm2, cardiac output fails to increase with exertion, causing angina (but may be normal at rest).
- With long-standing AS, the LV dilates, causing progressive LV dysfunction.
- With severe AS, LV dilation pulls the mitral valve annulus apart, causing MR.
- Calcification of a congenitally abnormal bicuspid aortic valve.
- Calcification of tricuspid aortic valve in elderly.
- Rheumatic fever.
Course and prognosis
- Patients are often asymptomatic for years (until middle or old age) despite the severe obstruction.
- The development of angina, syncope, or heart failure is a sign of poor prognosis. Survival is similar to that of the normal population before the development of these three classic symptoms. Without surgical intervention, survival is poor:
- Angina (35%)—average survival, 3 years
- Syncope (15%)—average survival, 2 years
- Heart failure (50%)—average survival, 1.5 years
- Altogether, only one-fourth of patients with symptomatic AS survives 3 years in the absence of aortic valve replacement (i.e., the 3-year mortality rate is 75% without surgery).
- Syncope—usually exertional
- Heart failure symptoms, such as dyspnea on exertion, orthopnea, or PND
- Aortic Stenosis murmur :
- Harsh crescendo–decrescendo systolic murmur Heard in second right intercostal space which radiates to carotid arteries
- Soft S2.
- S2 may also be single since the aortic component may be delayed and merge into P2. The softer the murmur, the more severe the AS
- S4 with progressive disease
- Parvus et tardus—diminished and delayed carotid upstrokes
- Sustained PMI
- Precordial thrill
- Aortic Stenosis murmur :
Features of Aortic stenosis murmur
Diagnosis of Aortic stenosis
- CXR findings: Calcific aortic valve, enlarged LV/LA (late)
- ECG findings: LVH, LA abnormality
- Echocardiography: standard test for hemodynamic and valve measurements for diagnosis of AS. Shows thickened, calcified aortic valve leaflets with limited mobility. Key measurements for diagnosis and severity are diminished valve area and increased ventricular-aortic pressure gradient
- Exercise stress testing is indicated for asymptomatic patients with severe AS to confirm asymptomatic status. These patients, despite having severe AS, do not require intervention. Should not be performed in symptomatic patients
- Cardiac catheterization
- Now used primarily in patients in whom echocardiography is nondiagnostic (i.e., poor visualization of the valve, difficulty obtaining pressure gradients with Doppler)
- Useful in symptomatic patients before surgery because it can also reveal coronary anatomy, allowing the surgeon to do both CABG and aortic valve replacement in patients with both CAD and severe AS
- Medical therapy has a limited role.
- Surgical therapy: Aortic valve replacement is the treatment of choice. It is indicated in all symptomatic patients.
Indications of Valve Replacement in Aortic Stenosis