Prenatal diagnosis of absent right with persistent left superior vena cava: a case series.

Persistence of a left superior vena cava (PLSVC) is the most common thoracic venous anomaly, seen in 0.3-0.5% of patients. In rare cases (0.07-0.13% of patients), however, it is associated with the absence of the right superior vena cava (RSVC), a condition known as isolated PLSVC, or IPLSVC (Kusaka et al. in JA Clin Rep, 2015; Bartram et al. in Am J Cardiol 80(2):175-183, 1997). Absent right with PLSVC itself is usually not hemodynamically significant; its discovery, however, has significant implications, specifically for future cardiac inventions such as cardiac catheterization and pacemaker placement. It is also associated with other pathologies such as coarctation of the aorta, right sided aortic arch, valvular abnormalities, and arrhythmias secondary to coronary sinus dilation (Kusaka et al. in JA Clin Rep, 2015; Bartram et al. in Am J Cardiol 80(2):175-183, 1997). For this reason, awareness of this anatomy and its variations remains critically important. It was traditionally found on autopsy or during the time of invasive cardiac procedures; but with advances in fetal echocardiography, it has become more common to be found prenatally, with an opportunity for follow-up to monitor for any complications and associated findings (Guarnier et al. in Pediatr Cardiol27(5):646-648, 2006; Kahramanoglu et al. Pediatr Cardiol 45(2):377-384, 2024). In the following series, we present the cases of seven individuals with maternal fetal echocardiographic evidence of absent right with PLSVC and associated findings on postnatal evaluation.