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For further information, see CMDT Part 10-46: Hypertrophic Cardiomyopathy

Key Features

  • Any wall thickness > 1.5 cm

  • The LV outflow tract is usually narrowed during systole between the hypertrophic septum and an anteriorly displaced anterior mitral valve leaflet, causing dynamic LV outflow obstruction (demonstrable on echocardiography as systolic anterior motion of the mitral valve)

  • Obstruction is worsened by sympathetic stimulation, digoxin, postextrasystolic beats, Valsalva maneuver, peripheral vasodilator drugs

  • Inherited form has autosomal dominant inheritance and usually presents in early adulthood

  • Acquired form presents as diastolic dysfunction in elderly patients with a long history of hypertension

  • Atrial fibrillation is a long-term consequence and a poor prognostic sign

  • Ventricular arrhythmias are common

  • Increased risk of sudden death

Clinical Findings

  • Often presents with dyspnea, chest pain, or syncope (typically postexertional)

  • Physical examination

    • Prominent "a" wave in jugular pulse

    • Bisferiens carotid pulse

    • Sustained or triple apical impulse

    • Loud S4

  • Loud systolic murmur along left sternal border that increases with upright posture or Valsalva maneuver and decreases with squatting

  • Mitral regurgitation is frequently present

  • See Table 10–17

Table 10–17.Classification of the cardiomyopathies.

Diagnosis

  • Chest radiograph: often unimpressive

  • ECG

    • LV hypertrophy However, normal ECGs are present in up to 25%

    • Exaggerated septal Q waves inferolaterally may mimic myocardial infarction

  • Doppler echocardiography

    • Ventricular hypertrophy, which may be asymmetric

    • Usually normal or enhanced contractility and signs of dynamic obstruction

    • Systolic anterior motion of mitral valve if outflow tract obstruction

    • Can confirm outflow tract gradient and diastolic filling abnormalities

  • Exercise studies are recommended to assess for ventricular arrhythmias and to document the blood ...

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