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. 2019 Mar 22;40(3):035002.
doi: 10.1088/1361-6579/ab0a2c.

Fetal magnetocardiogram waveform characteristics

Sarah A Strand  1 , Janette F Strasburger, Ronald T Wakai
Affiliations

Fetal magnetocardiogram waveform characteristics

Sarah A Strand et al. Physiol Meas. .

Abstract

Background: Fetal magnetocardiography (fMCG) is the most direct and precise method of assessing fetal rhythm and conduction. Although the utility of fMCG for evaluation of fetuses with serious arrhythmia is generally acknowledged, many aspects of fetal rhythm and conduction are relatively unstudied.

Objective: To record fMCG in a large group of normal fetuses in order to provide a more comprehensive evaluation of fMCG waveform characteristics, including waveform intervals, amplitudes, and morphology.

Methods: The subjects were 132 healthy women with uncomplicated singleton pregnancies, studied at 15.7-39.9 (mean 28.9) weeks' gestation in 259 sessions. The P, PR, QRS, QT, QTc, and RR intervals and the P/QRS and T/QRS amplitude ratios were measured.

Main results: The P, PR, QRS, and RR intervals increased with gestational age, but QT and QTc did not. U-waves were seen in 11% of fetuses. The T-waves were often flat with low T/QRS amplitude ratios. Equiphasic QRS complexes were associated with tall P-waves. The PR, QRS, and QT intervals showed a power law dependence on RR interval with power law exponents 0.445, 0.363, and 0.381, respectively.

Significance: The data establish prediction intervals for fMCG waveform intervals and amplitudes in normal fetuses. This is critical for identification of fetuses with abnormal rhythm. Our study is the first to document the incidence of U-waves and flat T-waves in the fetus, both of which are uncommon postnatally. The association of tall P-waves with equiphasic QRS complexes provides a useful means of improving the resolution of fetal P-waves.

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Conflict of interest statement

DISCLOSURE STATEMENT

The authors have no conflicts of interest to declare.

Figures

Fig. 1.
Fig. 1.
Averaged waveforms of duration 1-second, showing examples of a) typical waveform with intervals indicated, b) U-wave, c) equiphasic QRS complex with tall P-wave, and d) flat T-wave.
Fig. 1.
Fig. 1.
Averaged waveforms of duration 1-second, showing examples of a) typical waveform with intervals indicated, b) U-wave, c) equiphasic QRS complex with tall P-wave, and d) flat T-wave.
Fig. 1.
Fig. 1.
Averaged waveforms of duration 1-second, showing examples of a) typical waveform with intervals indicated, b) U-wave, c) equiphasic QRS complex with tall P-wave, and d) flat T-wave.
Fig. 1.
Fig. 1.
Averaged waveforms of duration 1-second, showing examples of a) typical waveform with intervals indicated, b) U-wave, c) equiphasic QRS complex with tall P-wave, and d) flat T-wave.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 2.
Fig. 2.
Scatter plots of a) P, b) PR, c) QRS, d) QT, e) QTc, and f) RR interval versus gestational age. The solid lines and dashed lines, respectively, show the linear regression line and the 95% prediction interval, and are computed using data from all sessions.
Fig. 3.
Fig. 3.
Scatter plots of a) P/QRS and b) T/QRS amplitude ratio versus gestational age. The P/QRS amplitude ratio was higher for equiphasic versus monophasic QRS complexes.
Fig. 3.
Fig. 3.
Scatter plots of a) P/QRS and b) T/QRS amplitude ratio versus gestational age. The P/QRS amplitude ratio was higher for equiphasic versus monophasic QRS complexes.
Fig. 4.
Fig. 4.
Log-log scatter plots of a) PR, b) QRS, and c) QT versus RR.
Fig. 4.
Fig. 4.
Log-log scatter plots of a) PR, b) QRS, and c) QT versus RR.
Fig. 4.
Fig. 4.
Log-log scatter plots of a) PR, b) QRS, and c) QT versus RR.
See this image and copyright information in PMC

References

    1. COMANI S, LIBERATI M, MANTINI D, MERLINO B, ALLEVA G, GABRIELE E, DI LUZIO S & ROMANI GL 2005. Beat-to-beat estimate of fetal cardiac time intervals using magnetocardiography: longitudinal charts of normality ranges and individual trends. Acta Obstet Gynecol Scand, 84, 1175–80. - PubMed
    1. CUNEO BF, STRASBURGER JF, YU S, HORIGOME H, HOSONO T, KANDORI A & WAKAI RT 2013. In utero diagnosis of long QT syndrome by magnetocardiography. Circulation, 128, 2183–91. - PMC - PubMed
    1. DAS B, CUNEO BF, OVADIA M, STRASBURGER JF, JOHNSRUDE C & WAKAI RT 2008. Magnetocardiography-guided management of an unusual case of isoimmune complete atrioventricular block complicated by ventricular tachycardia. Fetal Diagn Ther, 24, 282–5. - PMC - PubMed
    1. DEMARIA AN, BEN-YEHUDA O, BAX JJ, FELD GK, GREENBERG BH, LEW WY, LIMA JA, MAISEL AS, NARAYAN SM, SAHN DJ & TSIMIKAS S 2009. Highlights of the Year in JACC 2008. J Am Coll Cardiol, 53, 373–98. - PubMed
    1. DONOFRIO MT, MOON-GRADY AJ, HORNBERGER LK, COPEL JA, SKLANSKY MS, ABUHAMAD A, CUNEO BF, HUHTA JC, JONAS RA, KRISHNAN A, LACEY S, LEE W, MICHELFELDER EC SR., REMPEL GR, SILVERMAN NH, SPRAY TL, STRASBURGER JF, TWORETZKY W, RYCHIK J, AMERICAN HEART ASSOCIATION ADULTS WITH CONGENITAL HEART DISEASE JOINT COMMITTEE OF THE COUNCIL ON CARDIOVASCULAR DISEASE IN THE, Y., COUNCIL ON CLINICAL CARDIOLOGY, C. O. C. S., ANESTHESIA, COUNCIL ON, C. & STROKE, N. 2014. Diagnosis and treatmentof fetal cardiac disease: a scientific statement from the American Heart Association. Circulation, 129, 2183–242. - PubMed