CHAPTER 14: Hypertrophic Cardiomyopathy

ECHOCARDIOGRAPHIC FINDINGS

• This is a genetic disorder of the heart. Family members also may be affected. There is a risk of sudden death.

• Echocardiographic findings:

  • - Asymmetric left ventricular hypertrophy (Fig. 14-1).

  • - Dynamic left ventricular outflow obstruction (Fig. 14-2).

  • - Mitral systolic anterior motion (Fig. 14-3).

  • - “Depressurizing” mitral regurgitation.

  • - Diastolic relaxation is impaired.

  • - Preserved systolic left ventricular function.

MITRAL REGURGITATION IN HYPERTROPHIC CARDIOMYOPATHY

• Start by demonstrating systolic anterior motion of the mitral valve on 2D.

• Color flow should then confirm the sequence of:

  • - Ejection-obstruction-regurgitation (manifested on 2D by the SAM).

• Characteristic Doppler features of this jet:

  • - Direction: “opposite the culprit leaflet”—since the systolic motion is anterior, the direction of the jet is posterior.

• Timing:

  • - The predominant regurgitant flow is mid-to-late systolic (rather than holosystolic).

  • - The CW envelope has a characteristic “late-systolic-dagger” shape. Ejection starts, obstruction occurs, and regurgitation peaks in mid to late systole.

• Velocities:

  • - Since the regurgitation into the left atrium is “depressurizing” the dynamic left ventricular outflow tract obstruction, peak mitral regurgitation velocities are increased.

  • - Instead of the usual 5 m/s, they may exceed 6 m/s (Fig. 14-4).

• Caution:

  • - It is psychologically tempting to make the amateur mistake of confusing a 7 m/s mitral regurgitation velocity with an unrealistic 196 mm Hg outflow gradient. 4 × 7 × 7 = 196 is mathematically easy, tempting to calculate, but wrong as an outflow gradient. It is too high. Dynamic left ventricular outflow gradients rarely exceed 100 mm Hg.

  • - The true outflow gradient in a patient with a mitral regurgitation velocity ...