Synchronized Hemodynamic Rhythms in Twin Reversed Arterial Perfusion Sequence: A Case Report with Diagnostic and Pathophysiological Implications

Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic twin pregnancies, characterized by one structurally normal "pump" fetus perfusing an abnormal "acardiac" twin via placental vascular anastomoses. This case report presents a case of TRAP sequence diagnosed at 12 weeks' gestation, where serial ultrasound evaluations revealed a novel phenomenon of synchronized physiological rhythms between the pump twin's cardiac activity, the acardiac twin's arterial pulsations, and bilateral fetal movements，it's not an independent neural initiation or secondary mechanical displacement, it's a following neural initiation translated by the umbilical artery. Using a multidisciplinary approach combining obstetric ultrasound, fetal echocardiography, and real-time motion analysis, we documented 1: 1 synchronization of cardiac and arterial rhythms, with movement initiation occurring simultaneously in both fetuses on 92% of observed occasions. These findings challenge the traditional model of passive perfusion in TRAP sequence and suggest the existence of active neurovascular communication pathways between monochorionic twins. This case report provides a comprehensive review of TRAP sequence pathophysiology, presents detailed diagnostic methodology, discusses potential mechanisms underlying the observed synchronization, and concludes with implications for clinical management and future research directions.