Hypertrophic Cardiomyopathy
  • Disease that causes left ventricular hypertrophy
  • Autosomal dominant
  • Common disease affecting 1 in 500 people

Differential Diagnosis

Left ventricular hypertrophy is commonly seen on echocardiography. Therefore important to know the differential.

  • Hypertension
  • Aortic Stenosis
  • Amyloidosis
  • Anderson-Fabry Disease
  • High-level Athelete

 

High Yield Echo Features

  • Wall thickness
  • SAM (Systolic Motion of Mitral Valve)
  • Mitral Regurgitation
  • LVOT (Left Ventricular Outflow Track) obstruction
  • Diastolic Dysfunction

Wall Thickness

  • Unexplained LV wall of 15mm or more in any wall is pathologic
  • Commonly hypertrophic cardiomyopathy presents with assymetric. A ratio septal:posterior wall of greater 1.5:1 is pathologic.
  • Occasionally apex is more effected commonly referred to as apical hypertrophic cariomyopathy
  • Patient with hypertrophic cardiomyopathy.
  • Note significant left ventricular hypertrophy.
  • In the short axis there also is papillary muscle hypertrophy.

SAM (Systolic Anterior Motion of Mitral Valve)

  • Systolic anterior motion of the mitral valve is commonly seen in patients with HCM.
  • Since there is a thickened septum blood flow is high and turbulent through the LVOT.
  • The high flow of blood through the LVOT can draw the mitral valve anteriorly and towards the LV outflow track causing more obstruction. This is known as the Ventruri Effect.

 

  • Note the turbulent flow through the LVOT on colour doppler in the parasternal long axis view.
  • In the zoomed 5 chamber view you can visualize the mitral valve being sucked into the LVOT.
  • SAM can also be M-Mode through the mitral valve.

Mitral Regurgitation

  • Commonly seen in Hypertrophic Cardiomyopathy.
  • A posterior directed mitral regurgitation jet often accompanies SAM.
  • It temporally follows the onset of LVOT obstruction and care should be taken not to confuse its Doppler velocity profile with that of LVOT obstruction.

LVOT Obstruction

  • Pulse wave doppler should be used to localize site of obstruction.
  • Continuous wave doppler should be used to determine the peak.
  • If LVOT gradient less than 30 mmHg Valsalva should be attempted.
  • If no significant LVOT obstruction but patient symptomatic should consider Stress Echo.
  • Obstructive Physiology defined as a gradient conditions of ≥30 mm Hg.
  • Marked gradients ≥50 mm Hg, either at rest or with provocation, represent the conventional threshold for surgical or percutaneous intervention if symptoms cannot be controlled with medications.
  • Pulse wave doppler along the septal wall to localize the site of obstruction.
  • Note the step-up in gradient.
  • Commonly HCM PW/CW is described as “dagger shaped”.
  • Continuous wave doppler through the LVOT demonstrating a peak gradient of 33mmHg at rest
  • This is considered obstructive physiology.

Diastolic Dysfunction

  • Diastolic filling of the left ventricle is impaired in about 80% of individuals with HCOM
  • Can even be observed in asymptomatic patients without overt hypertrophy but who are genetically affected.
  • No clear relationship exists between the severity of hypertrophy and the severity of diastolic dysfunction.
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