Persistent left superior vena cava. Incidence, associated congenital heart defects and frontal plane P-wave axis in a paediatric population with congenital heart disease.

Among 3 671 patients aged 0-15 years with congenital heart disease diagnosed by cardiac catheterization and/or autopsy, 49 or 1.3% had a persistent left superior vena cava (PLSBC). The distribution of PLSVC among patients with various types of congenital heart disease did not suggest any causal relationship except in patients with pulmonary atresia and in patients with anomalous pulmonary venous connection, in whom PLSVC was found more frequently than expected by a mere chance relationship. Abnormal frontal plane P-wave suggesting ectopic pacemaker activity was found in 35% of the patients with PLSVC. The potential importance of PLSVC for the surgical risk during operation for congenital heart disease and for instability of the cardiac rhythm is emphasized.