Junctional ectopic tachycardia (JET) is an uncommon arrhythmia, but it can have devastating consequences when it occurs. Most physicians are not familiar with its diagnosis, which can seriously compromise management in emergency rooms. Many cases arise in the postoperative period following cardiovascular surgery. In this context, the arrhythmia significantly worsens the prognosis of patients. A particularly severe form of JET is congenital, which has a mortality rate of up to 35%. The diagnosis can be made from the fetal period to six months of age. JET is infrequently diagnosed in otherwise healthy adults. Some medical conditions have been associated with the occurrence of JET. In the electrocardiogram, the most prominent characteristics of the arrhythmia are atrioventricular dissociation, narrow QRS complexes, and R-R interval irregularity due to intermittent ventricular captures. A notable feature of JET is the lack of response to treatment in many patients. Management options are divided into general and specific measures. General measures include avoiding hyperthermia, pain control, and minimizing the use of exogenous catecholamines. Specific treatment involves antiarrhythmic drugs, temporary atrial pacing, and ablation.

This study aimed to explore the possible etiology and treatment of severe fetal tachycardia in the absence of organic disease and provide a reference for clinical management of severe fetal tachycardia.

A 29-year-old pregnant woman, with a gravidity 1 parity 0, presented with a fetal heart rate (FHR) of 243 beats per minute during a routine antenatal examination at 31 + 2 wk of gestation. Before termination of pregnancy at 38 wk of gestation, the FHR repeatedly showed serious abnormalities, lasting more than 30 min. However, the pregnant woman and the fetus had no clinical symptoms, and repeated examination revealed no organic lesions. The mother and the baby were regularly followed up.

This was a case of severe fetal tachycardia with no organic lesions and management based on clinical experience.