CHAPTER 9: Bicuspid Aortic Valve

ECHO FEATURES OF BICUSPID AORTIC VALVES

• Definition

  • - Bicuspid aortic valve: two instead of three semilunar aortic valve cusps.

  • - There are also rare patients with unicuspid and quadricuspid aortic valves.

• Cusp nomenclature

  • - The conjoined cusp is usually wider than normal and contains a raphe.

  • - Raphe: a ridge that extends from the aortic wall to the commissure of the conjoined cusp.

• Raphe height variants

  • - No evident raphe, just a “fishmouth” systolic opening.

  • - Shallow, difficult-to-image raphe.

  • - Classic thick visible raphe.

  • - Unusually tall raphe—rising as high as the free edge of the leaflets.

• Over time, the raphe may become calcified. Calcification is manifested on echo by acoustic shadowing past the raphe.

• Classification:

  • - Type 1: Fusion of the right and left coronary cusp (larger sinus diameter) (70%–86% incidence).

  • - Type 2: Fusion of the right and noncoronary cusp (associated tubular ascending aorta and dilated arch) (12%–28% incidence).

  • - Type 3: Fusion of the left and noncoronary cusp (rare incidence).

• Imaging:

  • - Parasternal long axis (PLAX) view provides the first clue to the presence of a bicuspid valve.

  • - Asymmetric diastolic leaflet closure line located on an “outside third” of the sinus of Valsalva (Fig. 9-1).

  • - Systolic doming.

  • - Diastolic prolapse.

• Short axis (SAX) view is used for definitive diagnosis. Sometimes transesophageal echocardiography (TEE) is needed for confirmation.

• Diastole may fool you: The closed valve may look perfectly normal on echo when a nonthickened raphe is present.

• Look for a thicker than normal, partly unseparated raphe in systole.

• Look for the systolic “fishmouth” opening.

• A commissure line may continue “past the center” without bending.

• A commissure may violate the 10–2–6 o’clock location.

• When the intercoronary (right to left) commissure is abnormal (type 1), the systolic opening has a horizontal orientation.

• When the right-to-noncoronary commissure is abnormal (type 2), the systolic opening has a vertical orientation.

• Doppler evaluation of the systolic gradient in bicuspid aortic valves:

  • - The maximum instantaneous Doppler gradient is typically higher than a peak-to-peak gradient measured by catheterization.

  • - The mean Doppler gradient is closer to the peak-to-peak gradient measured by catheterization.

  • - The discrepancy is explained in some cases by the presence of pressure recovery.

  • - Direct planimetry of 2D and 3D echo images should be done when feasible (making sure the smallest possible, “mouth of the volcano,” true stenosis orifice is used).

  • - In children with a stenotic bicuspid, or a unicuspid aortic valve, the presence of left ventricular hypertrophy indicates significant valve obstruction.

  • - Bicuspid aortic valve is associated with coarctation of the aorta.

Sources

• Espinola-Zavaleta N, Muñoz-Castellanos L, Attié F, et al. Anatomic three-dimensional echocardiographic correlation of bicuspid aortic valve. J Am Soc Echocardiogr. 2003;16:46–53.

• Michelena HI, Khanna AD, Mahoney D, et al. Incidence of aortic complications in patients ...