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Supraventricular electrical interaction in conjoined twins with common coronary sinus
T S Hornung1, G F Sholler, K C Lau
1Adolph Basser Cardiac Institute, Royal Alexandra Hospital for Children, Sydney, Australia.
Insights
Conjoined twins showed fused QRS complexes on ECG, initially suggesting shared ventricles. Pharmacological and pacing interventions revealed distinct ventricular electrical activity, confirming separation was possible.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Congenital Abnormalities
Background:
- Conjoined twins present unique diagnostic challenges, particularly regarding shared circulatory and electrical systems.
- Echocardiography suggested coronary sinus continuity, but ventricular myocardial continuity remained uncertain.
Observation:
- Electrocardiograms (ECG) revealed identical heart rates and broad, polyphasic QRS complexes in conjoined twins.
- Initial imaging failed to definitively assess ventricular myocardial continuity.
Findings:
- Adenosine administration clarified the broad QRS complexes as fused individual QRS complexes, enabling differentiation.
- Ventricular pacing induced dissociation of QRS complexes, proving the absence of ventricular myocardial continuity.
Implications:
- This study highlights the utility of pharmacological and electrophysiological testing in diagnosing complex congenital conditions.
- The findings confirm that even with apparent shared cardiac structures, distinct ventricular function can exist, guiding surgical separation outcomes.
Abstract:
Conjoined twins with echocardiographic evidence of continuity of the coronary sinuses had identical heart rates on ECG. Both had broad, polyphasic QRS complexes, and various imaging modalities were unable to determine whether there was ventricular myocardial continuity. Administration of adenosine demonstrated that the broad polyphasic complexes were a "fusion" of the twins' individual QRS complexes, which could be clearly distinguished after administration of the drug. Ventricular pacing resulted in dissociation of the individual QRS complexes, thus demonstrating an absence of ventricular myocardial continuity. This was confirmed when the twins were successfully separated at the age of 10 months.