Chapter 31-5: Aortic Stenosis

TEXTBOOK PRESENTATION

Aortic stenosis is usually diagnosed incidentally during routine exam rather than due to symptoms. Typically, aortic stenosis produces a loud crescendo-decrescendo systolic murmur at the right second intercostal space, which may radiate to the neck. When aortic stenosis becomes severe, patients may have any of the 3 cardinal symptoms: syncope, angina, or HF (dyspnea, typically with exertion).

DISEASE HIGHLIGHTS

1. Thickening and calcification of valve leaflets results in progressive obstruction to blood flow.

2. LVH develops to compensate for the obstruction.

3. Pathophysiology of the cardinal symptoms is shown in Figure 31-9.

4. Prevalence is 3% in patients ≥ 75 years old.

5. Etiology:

   1. Most commonly due to calcification of a trileaflet aortic valve

   2. Accelerated in patients with congenital bicuspid valve

      1. 1–2% of the population is born with a congenital bicuspid valve.

      2. Severe aortic stenosis develops in 66% of patients and at an earlier age than in patients with tricuspid valves.

      3. Aortic root structure is usually also abnormal and often associated with progressive dilation of the aortic root that may require repair to prevent rupture or dissection.

   3. Rheumatic heart disease

6. Severe aortic stenosis is characterized by a valve area < 1 cm, associated with an increased velocity across the aortic valve (≥ 4 m/s) and mean aortic valve gradient > 40 mm Hg. Gradients and velocities may be lower in patients with a low cardiac output.

7. Prognosis: Mortality increases markedly when symptoms develop (HF, angina, or syncope). The most common symptoms are decreased exercise tolerance and dyspnea on exertion. Mortality for symptomatic patients if they do not have valve replacement:

   1. Aortic stenosis and angina: 50% 5-year mortality

   2. Aortic stenosis and syncope: 50% 3-year mortality

   3. Aortic stenosis and dyspnea: 50% 2-year mortality

8. Other late manifestations:

   1. Atrial fibrillation may develop. This is often poorly tolerated because the LV is noncompliant and dependent on atrial contraction for filling.

   2. An increased bleeding tendency secondary to disruption of large von Willebrand multimers by the abnormal aortic valve.

EVIDENCE-BASED DIAGNOSIS

1. History and physical exam: Most studies demonstrate only a fair reproducibility between examiners.

   1. Findings that help suggest aortic stenosis

      1. Effort syncope in patients with a systolic murmur (LR+, 1.3–∞ LR−, 0.76)

      2. Slow carotid upstroke (sensitivity, 15–42%; specificity, 95–100%; LR+, 9.2–∞)

      3. Murmur radiating to right carotid (sensitivity, 71–73%; specificity, 90%; LR+, 7.5)

   2. Findings that help rule out aortic stenosis

      1. Absence of any murmur (LR−, 0.0)

      2. Absence of murmur below right clavicular head (LR−, 0.1)

   3. Murmurs may be less intense in patients with superimposed HF.

2. Echocardiogram

   1. The initial test of choice to assess for aortic stenosis

   2. Recommended for patients with a systolic murmur ≥ grade III/VI

   3. Criteria for severe aortic stenosis is a flow rate > 4.0 m/s corresponding to a valve area < 1.0 cm² and a gradient of ≥ 40 mm Hg.

   4. Patients with ...