Supraventricular electrical interaction in conjoined twins with common coronary sinus

Conjoined twins with echocardiographic evidence of continuity of the corona ry sinuses had identical heart rates on EGG. Both had broad, polyphasic QRS complexes, and various imaging modalities were unable to determine whether there was ventricular myocardial continuity. Administration of adenosine d emonstrated that the broad polyphasic complexes were a "fusion" of the twin s' individual QRS complexes, which could be clearly distinguished after adm inistration of the drug. Ventricular pacing resulted in dissociation of the individual QRS complexes, th us demonstrating an absence of ventricular my ocardial continuity. This was confirmed when the twins were successfully se parated at the age of 10 months.