- Clinical science
Aortic stenosis (AS) is a valvular heart disease characterized by narrowing of the aortic valve. As a result, the outflow of blood from the left ventricle into the aorta is obstructed. This leads to chronic and progressive excess load on the left ventricle and potentially left ventricular failure. The patient may remain asymptomatic for long periods of time; for this reason, AS is often detected late, i.e., when it first becomes symptomatic (dyspnea on exertion, angina pectoris, or syncope). Auscultation reveals a harsh, crescendo-decrescendo murmur in systole that radiates to the carotids, and pulses are delayed with diminished carotid upstrokes. Echocardiography is the gold standard for diagnosis. Patients with asymptomatic aortic stenosis are treated conservatively. Symptomatic patients or those with severe aortic valve stenosis require valve replacement.
By location of obstruction
- Valvular: most common
- Calcific aortic stenosis: most common cause of aortic stenosis
- is a rare cause of AS in developed countries, but continues to remain a significant cause in developing countries.
- Narrowed opening area of the aortic valve during systole → obstruction of blood flow from left ventricle (LV) → increased LV pressure → left ventricular concentric hypertrophy →
- Initially, cardiac output (CO) can be maintained. Later, the decreased distensibility of the left ventricle reduces cardiac output and may then cause backflow into the pulmonary veins and capillaries → higher afterload (pulmonic pressure) on the right heart → right heart failure (see )
- The disease may remain asymptomatic for years (particularly with mild or moderate stenosis).
- Symptoms typically present on exertion, unless AS is severe
- Angina pectoris
- Dizziness and syncope
- Small blood pressure amplitude, decreased pulse pressure
- Cardiac exam (see
- Delayed and weak pulse (Pulsus parvus et tardus)
- Palpable systolic thrill over the bifurcation of the carotids and the aorta
- Harsh crescendo-decrescendo (diamond-shaped), late systolic ejection murmur that radiates bilaterally to the carotids
- Soft S2
- S4 is best heard at the apex.
- Early systolic ejection click
- Frequently associated with aortic regurgitation (see )
- Additional signs specific to infants: wheezing and difficulty feeding
Without definite treatment (surgery), more than 50% of the symptomatic patients with severe aortic stenosis will die within the first 2 years of diagnosis!
- Nonspecific for AS
- Signs of left ventricular hypertrophy (e.g., left axis deviation, positive )
- Findings of left ventricular hypertrophy, such as left ventricular enlargement and rounded heart apex, usually only in decompensated aortic stenosis, and possibly left atrial enlargement as well
- Narrowing of retrocardiac space (lateral view)
- Calcification of aortic valve: signs of more severe disease
- Transthoracic (TTE) or transesophageal (TEE): preferred primary test and noninvasive gold standard
- Definitive diagnostic test
- Indication: inconclusive echocardiogram
- Risk of cerebral embolization
- Conservative management: regular follow-ups indicated for asymptomatic patients with mild aortic stenosis
Surgical (see )
- Symptomatic patients
- Asymptomatic patients with severe AS and either significantly ↓ LV EF or those undergoing cardiac surgery
Aortic valve replacement (AVR): 3 possible approaches
- Surgical AVR: patients with low surgical risk.
- Transcatheter AVR (TAVR): patients with high surgical risk or contraindication
- Catheter balloon valvuloplasty: children without AV calcification