Ventricular couplets and arrhythmogenic right ventricular dysplasia

ECG: Sinus rhythm (positive P wave in leads I, II and negative in aVR); normal PR; incomplete right block pattern; negative T waves in V1-V2; premature ventricular complexes couplets: premature beats with broad, monomorphic QRS (same pattern for both consecutive extrasystoles); probable right outflow tract origin (positivity in inferior leads and V6, negativity in V1, late QRS transition in V4);

Comments: Ventricular couplets are the succession of two consecutive premature ventricular complexes. Beyond three or five consecutive premature ventricular complexes (depending on definition), it is common to use the term nonsustained ventricular tachycardia (if lasting less than 30 seconds).

Premature ventricular complexes in the setting of arrhythmogenic right ventricular dysplasia usually originate from the right ventricle (left delay) and are related to the location of the fibro-adipose infiltrates. They are shorter, wider, and often polymorphic and notched (different pathological foci, along with slowed and disorganized propagation within the ventricular myocardium), allowing to differentiate these asystoles from benign infundibular premature ventricular complexes. The response to catecholaminergic stimulation (exercise test, isoproterenol test) also differs with a significant increase in exercise irritability. Premature complexes are sometimes the first sign of the onset of this cardiomyopathy.

Take-home message: In arrhythmogenic right ventricular dysplasia, the premature ventricular complexes originate primarily from the pulmonary infundibulum (RV outflow tract) but may also originate from the apex and the sub-tricuspid region (triangle of dysplasia); they are generally notched, wider and shorter than benign premature ventricular complexes although differentiation is sometimes difficult; the presence of more than two different morphologies in indicative of the presence of a heart disease.