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. 2017 Aug 30;3(11):503–508. doi: 10.1016/j.hrcr.2017.07.022

Figure 1.

Figure 1

Case 1: Fetal magnetocardiography (fMCG) recordings during and after junctional ectopic tachycardia (JET). A: MCG fetal heart rate (FHR) trend recording over 10 minutes at 20 weeks gestational age (GA) during incessant JET (181 beats per minute). Low FHR variability is seen, except during ventriculoatrial (VA) dissociation with resultant sinus capture (horizontal arrows). Periods of VA dissociation are associated with increased beat-to-beat heart rate variability and spikes in FHR owing to shortened R-R intervals from conducted beats. B: fMCG rhythm tracing at 20 weeks GA during JET. The sinus P waves are indicated by upward arrows. Retrograde P waves are indicated by downward arrows. The 2 early beats (asterisks) are preceded by a P wave and have different QRS morphology, consistent with conducted sinus capture beats. These support that antegrade atrioventricular node conduction is still present. C: Signal-averaged butterfly (20 weeks GA) showing retrograde bifid P waves occurring within the lower-amplitude T waves. QTc is prolonged. Cardiac intervals are as follows: R-R = 333 ms, VA = 77 ms, QRS = 33 ms, and QTc = 513 ms. D: Signal-averaged butterfly plot at 25 weeks GA during sinus rhythm showing tall P waves and P-R prolongation.