Assessment of atrioventricular conduction by echocardiography and magnetocardiography in normal and anti-Ro/SSA-antibody-positive pregnancies

Abstract

Objectives: The objectives of this study were, first, to evaluate the association between fetal echocardiographic atrioventricular (AV) and magnetocardiographic (fMCG) PR intervals at different gestational ages (GAs) in normal and anti-Ro/SSA-antibody-positive pregnancies; second, to determine if PR interval could be predicted by AV interval; and third, to assess the neonatal outcome of fetuses with prolonged AV and PR intervals, with the goal of developing criteria for fetal first-degree AV block (AVB-I).

Methods: This was a retrospective study of anti-Ro/SSA-antibody-positive pregnancies (cases) and controls that underwent fMCG and fetal echocardiography at the same recording session. Cardiac cycle length, GA and AV (by mitral inflow/aortic outflow Doppler) and PR (by fMCG) intervals were measured. We tested for significant differences between AV and PR intervals using generalized estimating equations to account for repeat measurements, and assessed whether PR interval could be predicted reliably by AV interval. After delivery, infants with fetal AV or PR interval Z-score ≥ 3 underwent 12-lead electrocardiography.

Results: Thirty-nine controls and 31 cases underwent 46 and 36 simultaneous fMCG and echocardiographic examinations, respectively; 101 controls and nine cases underwent fMCG only. AV and PR intervals increased with GA (P < 0.05 for both). Overall, AV and PR intervals were significantly different from each other (P < 0.001); this difference was not significant when compared between cases and controls (P = 0.222). PR interval could not be predicted accurately from AV interval and GA alone. Three of four cases with AV and PR interval Z-scores > + 3 had postnatal AVB-I despite treatment. The fourth fetus, which had predominately second-degree AVB and rare periods of AVB-I, progressed to third-degree AVB despite treatment with dexamethasone.

Conclusions: The diagnostic threshold for AVB-I, defined by AV interval Z-score, is GA dependent. Based on the observed data, an AV interval Z-score threshold of 3 (AV interval, 151-167 ms) may be appropriate. Echocardiographic AV interval was not predictive of fMCG-PR interval. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Keywords: AV block; Sjögren's syndrome; fetal magnetocardiography; fetus.

Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Figures

Figure 1.

Signal averaged fMCG (butterfly plots), echo Doppler tracings and postnatal ECGs of fetuses with prolonged AV and PR intervals. (A). Subject 5. The fMCG AV interval is 146 ms, the simultaneous Doppler PR interval is 185 ms, and the postnatal ECG PR interval is 160 ms. (B). Subject 7. The fMCG AV interval is 210 ms and the Doppler PR interval is 225 ms. The postnatal ECG shows complete AV block. P-waves are shown by red arrows. Some intervals in Figure 1 are different than in Table 6 because the former was averaged.

Figure 1.

Signal averaged fMCG (butterfly plots), echo Doppler tracings and postnatal ECGs of fetuses with prolonged AV and PR intervals. (A). Subject 5. The fMCG AV interval is 146 ms, the simultaneous Doppler PR interval is 185 ms, and the postnatal ECG PR interval is 160 ms. (B). Subject 7. The fMCG AV interval is 210 ms and the Doppler PR interval is 225 ms. The postnatal ECG shows complete AV block. P-waves are shown by red arrows. Some intervals in Figure 1 are different than in Table 6 because the former was averaged.

Figure 2:

Bland-Altman plot for the observed and the predicted PR intervals from the model including gestational age (GA), AV interval, and their interaction. The average of observed and predicted is displayed on the x-axis and the difference between the predicted and observed is displayed on the y-axis.

Figure 3

(A): Predicted PR intervals versus gestational age for 4 different AV intervals (95 ms, 115 ms, 135 ms and 155 ms). (B): The predicted PR interval versus gestational age for an AV interval of 120 ms. The wide range between the 97.5th % (top dotted line) and 2.5th (bottom dotted line) shows the challenge of predicting an accurate PR interval from an AV interval at any gestational age.

Figure 3

(A): Predicted PR intervals versus gestational age for 4 different AV intervals (95 ms, 115 ms, 135 ms and 155 ms). (B): The predicted PR interval versus gestational age for an AV interval of 120 ms. The wide range between the 97.5th % (top dotted line) and 2.5th (bottom dotted line) shows the challenge of predicting an accurate PR interval from an AV interval at any gestational age.

Figure 4

Echo AV intervals versus gestational age in controls (triangles) and (circles) with z-scores. Fetuses born with 1° AVB block (solid purple circles) and 3° AVB (solid purple square). The Z-score of 0 is shown as the solid line.

Figure 5:

FMCG PR intervals versus gestational age in controls (triangles) and cases (circles) with z-scores. Fetuses born with 1° AVB (solid purple circles) and 3° (solid purple square). The z-score of 0 is shown as the solid line.