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Arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a type of cardiomyopathy which is diagnosed on the basis of number of criteria which include structural, functional, electrocardiographic, arrhythmic, and genetic factors. ARVD is recognized as a major cause of sudden death in adolescents, with one series reporting that it accounted for 20 percent of sudden deaths in all individuals younger than 35 years and 22 percent of sudden deaths in young atheletes.

Young adults with suspected ARVD clinically present with ventricular arrhythmias with a left bundle branch block (LBBB) pattern. Repolarization abnormalities, depolarization or conduction abnormalities, arrhythmias, and family history are all important factors in establishing the diagnosis. Global or regional dysfunction and structural alterations are also important criteria in the diagnosis of ARVD.

Imaging plays a significant role in the evaluation of ARVD. It has included right ventricular angiography and echocardiography, yet these modalities lack the spatial resolution necessary to diagnose the fatty/fibrofatty changes of the right ventricular myocardium typically found in ARVD. Magnetic resonance (MR) imaging provides high spatial resolution and is therefore the modality best suited to providing a comprehensive evaluation of the right ventricle and the associated changes in ARVD.

Key Points

  • MR imaging demonstrates morphologic and functional abnormalities commonly found in patients with ARVD, including fibrofatty replacement of the right ventricular free wall, abnormal morphology or “buckling,” and abnormal function. Fibrofatty replacement of the right ventricle is best evaluated in dark blood sequences, as bright blood sequences offer no contrast with the bright fatty infiltration. Abnormal function is best evaluated on cine TrueFISP (true fast imaging with steady-state precessional) sequences.
  • The typical criteria that can be demonstrated with MR imaging include:
    • Fatty infiltration of the right ventricular myocardium with high signal on T1-weighted images (major criterion);
    • Fibrofatty replacement, which leads to diffuse thinning of the right ventricular myocardium (major criterion);
    • Aneurysms of the right ventricle and right ventricular outflow tract (major criterion);
    • Dilatation of the right ventricule and right ventricular outflow tract (when severe, major criterion; when mild, minor criterion);
    • Regional contractile abnormalities (minor criterion); and
    • Global systolic dysfunction (major criterion) and global diastolic dysfunction (minor criterion).
  • The diagnosis of ARVD may have important consequences for direct relatives, because they have an increased change of having the disease, with an increased risk of sudden death. Screening of relatives can be performed non-invasively.
  • Findings on the MR exam must be taken in the context of the clinical diagnosis of ARVD, and a negative MR imaging study does not exclude the diagnosis of ARVD.

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