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The
signal-averaged electrocardiogram is usually abnormal in ARVD patients
who have sustained ventricular tachycardia. An abnormal signal averaged ECG
is supportive of the diagnosis of ARVD but a negative test does not exclude
this diagnosis. SAECG protocol The right ventricle has an irregular shape and is heavily trabeculated. Its contraction pattern is not concentric and uniform Therefore, slight abnormalities either may be undetected or it may be difficult to be certain that an abnormality in fact, does exist. Right ventricular size, volume, and contractility must be quantitated using standardized views in order to differentiate normal from abnormal right ventricular structure and function. ARVD does not affect the right ventricle uniformly. The right ventricular free wall is involved in particular locations, especially the right ventricular outflow tract, the right ventricular apex, and the posterior subtricuspid area. The septum is usually spared.
Echocardiography when properly performed by focusing attention on
right ventricular function and wall motion abnormalities is an excellent way
of screening for ARVD. The posterior and inferior wall of the right
ventricular inflow tract under the tricuspid valve is the most important
region that must be visualized because it is most frequently affected. This
may be seen in the parasternal long axis view with the probe angled toward
the inferior vena cava or the liver. Another projection to visualize this
area as well as the RV apex is the apical RV two-chamber view with the probe
angled toward the right ventricle by 20-30 degrees.The
angiographic features of arrhythmogenic right ventricular dysplasia (ARVD)
include global and/or regional function and morphological abnormalities of
the right ventricle including localized akinetic or dyskinetic bulges, outpouchings,
dilatation of the infundibulum, trabecular hypertrophy and/or disarray with
deep fissures. The study has a
standardized echo protocol and the Echo Core Laboratory is under the
direction of Dr. Michael Picard, Massachusetts General Hospital. The
following link will open a new window with a PowerPoint presentation.
Once an RV angiogram has been performed with appropriate views and adequate contrast, interpretation of wall motion abnormalities pose a distinct challenge, particularly when minor abnormalities are suspected. At present, angiography appears to be most reliable for the above assessment, although in the future, 3D echocardiography and MRI may be used in place of angiography for the evaluation of structure and function of the right ventricle. The study has a standardized angiogram protocol and the Angiogram Core Laboratory is under the direction of Dr. Thomas Wichter, Muenster, Germany. |
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