Fetal Supraventricular Tachycardia: What Do We Know up to This Day?

Fetal tachyarrhythmias, particularly supraventricular tachycardia (SVT) and atrial flutter (AFL), pose significant clinical challenges, especially when complicated by hydrops fetalis. This article provides a comprehensive review of the tachyarrhythmia types, the diagnostic modalities applied, and the therapeutic strategies followed in fetal tachyarrhythmias. Diagnostic techniques such as M-mode echocardiography and fetal magnetocardiography (fMCG) are highlighted for their capacity to provide real-time, high-quality assessments of fetal cardiac rhythms. The review, also, focuses on pharmacologic management via transplacental therapy, discussing the safety and efficacy of the key agents including digoxin, flecainide, and sotalol, under different clinical scenarios, such as hydropic fetus and renal impairment. In addition to transplacental administration, alternative approaches such as direct fetal intramuscular or intravascular injections are examined. These direct methods, while potentially more effective in refractory cases, carry risks that necessitate specialized expertise and careful consideration of maternal and fetal safety. The limitations of current evidence, largely based on small case studies and retrospective analyses, underscore the need for larger, prospective multicenter observational studies and randomized control trials to establish standardized protocols for fetal tachyarrhythmia management. Overall, this review advocates for a personalized, multidisciplinary approach, emphasizing early fetal tachyarrhythmias diagnosis, tailored treatment regimens that balances efficacy with safety, and rigorous monitoring to optimize outcomes for both the fetus and the mother.