Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disorder (autosomal dominant transmission), with primary involvement of the cardiac muscle. If associated with left ventricular outflow tract (LVOT) obstruction, it is called hypertrophic obstructive cardiomyopathy (HOCM).
HCM is characterized by localized or generalized unexplained left ventricular hypertrophy (LVH) in the non-dilated ventricle in the absence of any cardiac or systemic disease that can result in this magnitude of hypertrophy.
Usually, LV wall thickness is ≥15 mm in adults and ratio of IVS thickness to posterior wall thickness is ≥1.3/1. Systolic anterior motion (SAM) is the abnormal movement (sharp bending) of the anterior mitral valve (MV) leaflet toward the interventricular septum during systole.
LVOT obstruction happens as a result of both significant septal thickening and concomitant SAM of the mitral leaflets into the LVOT. Continuous-wave Doppler flow of the LVOT is characteristically dagger shaped and has a late-peaking velocity due to an increased obstruction as systole progresses. MR due to SAM is a mid-to-late systolic, eccentric, and posteriorly directed jet.
Several studies in patients with HCM have demonstrated a significant reduction in longitudinal strain (particularly in the mid-septal segment) with normal systolic twist or torsion.
KeywordsHypertrophic cardiomyopathy Hypertrophic obstructive cardiomyopathy Left ventricular outflow tract obstruction Asymmetric septal hypertrophy Systolic anterior motion
Asymmetric septal hypertrophy
Coronary artery disease
Cardiac magnetic resonance
Peak E-wave velocity of the mitral valve (cm/s)
TDI of the mitral annulus
Hypertensive heart disease
Hypertrophic obstructive cardiomyopathy
Implantable cardioverter defivrillators
Late gadolinium enhancement
Left ventricular ejection fraction
Left ventricular hypertrophy
Left ventricular outflow tract
Nonsustained ventricular tachycardia
New York Heart Association
Systolic anterior motion
Sudden cardiac death
Tissue Doppler imaging
(related to Fig. 22.2): ASH and SAM in para-sternal long axis view; SAM is best appreciated in the MV M-mode recordings of parasternal long-axis views (AVI 7146 kb)
MR due to SAM is a mid-to-late systolic, eccentric, and posteriorly directed jet (which is a common finding in HOCM) (AVI 808 kb)
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