Study design and methods
|
Year of Publication
|
1990
|
2003
|
2005
|
2005
|
2009
|
2015
|
2015
|
2017
|
Study design
|
Cross sectional study
|
Cross sectional study
|
Prospective cohort study
|
Cross sectional study
|
Cross sectional study
|
Cross sectional study
|
Prospective observation cohort study
|
Cross sectional study
|
Inclusion criteria
|
None reported
|
Random sampling
|
Healthy women and fetuses only
|
Women in labour or threatened labour
|
None reported
|
Referred for fetal echocardiography
|
Fetuses with normal cardiac anatomy or CHD
|
Healthy fetuses only
|
Gestational Age [weeks]
|
32 to 41
|
15 to 41
|
18 to 41
|
24 to 41
|
32 to 41
|
16 to 42
|
20 to 38
|
32 to 40
|
Time interval examined
|
PR, QRS, QT
|
PR, QRS, QT, QTc
|
P, PR, QRS, QT, T
|
PR, PQ, QRS, QT, QTc
|
P, QRS, T
|
PR, QRS, RR, QT
|
PR, QRS, QT
|
PR, PQ, QRS, QT, QTc
|
Number of patients
|
Not described
|
241
|
100
|
15
|
48
|
50
|
92
|
149
|
Number of acquired FECG
|
21
|
250
|
374
|
15
|
48
|
60
|
177
|
149
|
Signal acquisition
|
Number of electrodes
|
2
|
14
|
3
|
14
|
5
|
5
|
5
|
5
|
Electrodes placement
|
Not described
|
12 evenly over abdomen, 1 ground ref. near navel, 1 common ref. on right ankle
|
Equilateral triangle formation: 1 right + 1 left hypochondriac area, 1 above symphysis pubis
|
12 evenly over abdomen, 2 references near umblicus
|
2 higher abdomen (right/left), 2 lower abdomen (right/left), 1 at distinct fetal heart sound location
|
2 along midline, 2 at each side of uterus, 1 on left flank
|
2 along midline, 2 at each side of uterus, 1 on left flank
|
2 along midline, 2 at each side of uterus, 1 on left flank
|
Dermabrasion & impedance
|
None described
|
Yes (< 5 kΩ)
|
Yes(< 5 k Ω)
|
Yes (< 5 kΩ)
|
None reported
|
Yes
|
Yes
|
Yes
|
Reported difficulty in signal acquisition
|
None reported
|
Between 27 and 36 weeks
|
Between 27 and 32 weeks
|
None reported
|
None reported
|
Between 26 and 30 weeks
|
Between 24 and 34 weeks
|
Lowest at 32 weeks
|
Signal processing
|
FECG analysed
|
21
|
199
|
374
|
12
|
35
|
20
|
132
|
117
|
Signal averaging for analysis
|
100 beats
|
1 min
|
2.5 min
|
1 min
|
300–500 beats
|
1 min
|
yes - not described
|
1000 beats
|
Digital filters
|
4-pole Butterworth non-recursive 10 Hz Highpass
|
1–2 Hz Highpass, 150 Hz lowpass
|
1st & 2nd derivative template removal
|
1 Hz Highpass, 150 Hz Low pass
|
0.5 Hz low-level an 25 Hz high level removal
|
[0.5–70 Hz] Butterworth bandpass
|
Automated with Monica DK V1.8 software
|
Not reported
|
MECG removal
|
Digital subtraction of averaged signal
|
See Patent appl. GB2002/004410
|
Template subtraction
|
See Patent appl. GB2002/004410
|
Template subtraction
|
Template matching and digital subtraction
|
Automated with Monica DK V1.8 software
|
Template subtraction
|
Success rates in CTI detection
|
QT-80%
|
P,Q, R, S-100%; T-78%
|
P-74.6%, QRS-91.0%, T-79.3%
|
P, QRS-100%, T-92%
|
72.9%
|
100% due to strict FECG excl. Criteria
|
PR-77%, QRS-98%, QT-30%
|
P, PQ, PR-97%, QRS-100%, T-41%
|