CHAPTER 8: Aortic Valve Stenosis

AORTIC STENOSIS

• Onset of symptoms in patients with severe aortic stenosis indicates a reduced life expectancy if the aortic stenosis remains untreated.

• Extensive aortic valve calcification on 2D imaging indicates a worse prognosis and is manifested as:

  • - Increased leaflet echogenicity (brightness).

  • - Increased leaflet thickness.

  • - Prominent acoustic shadowing artifacts created by the calcified leaflets.

• Physical inactivity, concomitant coronary artery disease, renal failure, and older age also predict adverse events.

• Calculation of aortic stenosis severity determines subsequent course of action:

  • - Clinical observation.

  • - Surgical aortic valve replacement.

  • - Transcatheter aortic valve replacement.

  • - Temporary balloon valvuloplasty.

• Extent of echocardiographic cardiac damage is being used to stratify aortic stenosis:

  • - Stage 0: No cardiac damage.

  • - Stage 1: LV damage.

  • - Stage 2: LA or mitral damage.

  • - Stage 3: Pulmonary vasculature or tricuspid damage.

  • - Stage 4: RV damage.

Sources

• Généreux P, Pibarot P, Redfors B, et al. Staging classification of aortic stenosis based on the extent of cardiac damage. Eur Heart J. 2017;38:3351–3358.

• Lindman BR, Clavel MA, Mathieu P, et al. Calcific aortic stenosis. Nat Rev Dis Primers. 2016;2:16006.

• Technical aspects of aortic stenosis quantitation:

  • - The continuity equation compares left ventricular outflow tract (LVOT) stroke volume to aortic stenosis stroke volume.

  • - Measurement of LVOT diameter is the most important source of error in calculation of aortic stenosis valve area. LVOT shape is oval; it can be both foreshortened and exaggerated with improper technique. Hint: Compare LVOT diameters at different parasternal rib interspaces. Look for diameters close to 2 cm by adjusting transducer angulation (Fig. 8-1).

  • - The simplified Bernoulli equation is unreliable when left ventricular outflow velocities are abnormally increased (increased flow due to significant aortic valve regurgitation, increased subaortic gradient due to subaortic obstruction).

  • - Doppler measurements of flow velocities are affected by angle of interrogation. Doppler examination has to be as parallel to flow as possible. Maximum Doppler velocities are obtained by using all available acoustic windows: apical, suprasternal, right parasternal, and even subcostal (Fig. 8-2).

  • - Pressure recovery is important for comparing discrepancies in catheter-derived gradients to Doppler-derived ...