Fetal Echocardiography and Magnetocardiography

Number: 0106

Policy

1. Aetna considers fetal echocardiograms, Doppler and color flow mapping medically necessary after 12 weeks gestation for any of the following conditions:

   1. A mother with insulin dependent diabetes mellitus or systemic lupus erythematosus; or
   2. As a screening study in families with a first-degree relative of a fetus with congenital heart disease; or
   3. Fetal nuchal translucency measurement of 3.5 mm or greater in the first trimester; or
   4. Following an abnormal or incomplete cardiac evaluation on an anatomic scan, 4-chamber study

      (Note: When the 4-chambered view is adequate and there are no other indications of a cardiac abnormality, a fetal echocardiogram is not considered medically necessary); or

   5. For ductus arteriosus dependent lesions and/or with other known complex congenital heart disease; or
   6. For pregnancies conceived by in vitro fertilization (IVF) or intra-cytoplasmic sperm injection (ICSI); or
   7. In cases of persistent right umbilical vein; or
   8. In cases of single umbilical artery; or
   9. In cases of suspected or known fetal chromosomal abnormalities; or
   10. In suspected or documented fetal arrhythmia: to define the rhythm and its significance, to identify structural heart disease and cardiac function; or
   11. In members with autoimmune antibodies associated with congenital cardiac anomalies [anti-Ro (SSA)/anti-La (SSB)]; or
   12. In members with familial inherited disorders associated with congenital cardiac abnormalities (e.g., Marfan syndrome); or
   13. In cases with monochorionic twins; or
   14. In cases of multiple gestation and suspicion of twin-twin transfusion syndrome; or
   15. In members with seizure disorders, even if they are not presently taking anti-seizure medication; or
   16. In cases with non-immune fetal hydrops or unexplained severe polyhydramnios; or 
   17. When members' fetuses have been exposed to drugs known to increase the risk of congenital cardiac abnormalities including but not limited to:
       
       
       • Anti-seizure medications; or
       • Excessive alcohol intake; or
       • Lithium; or
       • Paroxetine (Paxil); or
       • Retinoids; or
         
   18. When other structural abnormalities are found on ultrasound; or 

2. Aetna considers repeat studies of fetal echocardiograms medically necessary when the initial screening study indicates any of the following:

   • A ductus arteriosus dependent lesion; or
   • Structural heart disease with a suggestion of hemodynamic compromise; or
   • Tachycardia other than sinus tachycardia or heart block.

3. Aetna considers fetal echocardiograms experimental and investigational for all other indications including the following (not an all-inclusive list) because their effectiveness for these indications has not been established.

   • As a screening test in advanced maternal age; or
   • Pregnant women receiving selective serotonin reuptake inhibitors (except paroxetine); or
   • Suspected cystic fibrosis.
     
     
4. Aetna considers fetal magnetocardiography experimental and investigational because its effectiveness has not been established.

Background

Definition of fetal cardiac structures is currently possible at 12 weeks of gestation with the use of vaginal probes with high-resolution transducers.  With current technologies, accurate segmental analysis of cardiac structures and blood flow across valves, shunts, and the ductus arteriosus is possible with a conventional transabdominal approach by 16 to 18 weeks of gestation.

According to the American Institute for Ultrasound in Medicine (AIUM), fetal echocardiography is commonly performed between 18 and 22 weeks’ gestational age. Some forms of congenital heart disease may even be recognized during earlier stages of pregnancy (AIUM, 2013). Newer technology including endovaginal transducers can obtain images of the heart as early as 12 weeks gestation (AHA, 2018).

Hutchinson et al. (2017) states that early fetal echocardiography (FE), performed at 12 to 16 weeks' gestational age (GA), can be used to screen for fetal heart disease similar to that routinely performed in the second trimester; however, the efficacy of FE at earlier GAs has not been as well explored, particularly with recent advances in ultrasound technology. Pregnant women were prospectively recruited for first-trimester FE. All underwent two-dimensional (2D) cardiac imaging combined with color Doppler (CD) assessment, and all were offered second-trimester fetal echocardiographic evaluations. Fetal cardiac anatomy was assessed both in real time during FE and additionally offline by two separate reviewers. Very early FE was performed in 202 pregnancies including a total of 261 fetuses, with 92% (n = 241) being reassessed at greater than or equal to 18 weeks' GA. Transabdominal scanning was used in all cases, and transvaginal scanning was used additionally in most at less than 11 weeks' GA (n = 103 of 117 [88%]). There was stepwise improvement in image resolution of the fetal heart in those pregnancies that presented at later gestation for assessment. CD assisted with definition of cardiac anatomy at all GAs. A four-chambered heart could be identified in 52% of patients in the eighth week (n = 12 of 23), improving to 80% (n = 36 of 45) in the 10th week and 98% (n = 57 of 58) by the 11th week. The inferior vena cava was visualized by 2D imaging in only 4% (n = 1 of 23) in the eighth week, increasing to 13% (n = 6 of 45) by the 10th week and 80% (n = 25 of 31) by the 13th week. CD improved visualization of the inferior vena cava at earlier GAs to greater than 80% (n = 37 of 45) from 10 weeks. Pulmonary veins were not visualized by either 2D imaging or CD until after the 11th week. Both cardiac outflow tracts could be visualized by 2D imaging in the minority from 8+0 to 10+6 weeks (n = 18 of 109 [16%]) but were imaged in most from 11+0 to 13+6 weeks (n = 114 of 144 [79%]). CD imaging improved visualization of both outflow tracts to 64% (n = 29 of 45) in the 10th week. On 2D imaging alone, both the aortic and ductal arches were seen in only 29% of patients in the 10th week (n = 13 of 45), increasing to 58% when CD was used (58% [n = 26 of 45]) and to greater than 80% (n = 47 of 58) using CD in the 11th week. The authors concluded that very early FE, from as early as 8 weeks, can be used to assess cardiac structures; however, the ability to image fetal heart structures between 6 and 8 weeks is currently nondiagnostic. The use of CD significantly increases the detection of cardiac structures on early FE. The ideal timing of complete early FE, excluding pulmonary vein assessment, appears to be after 11 weeks' GA.

Ventriglia et al. (2016) state that there is a growing body of evidence that most of the major cardiac abnormalities can be diagnosed from 12-16 weeks of gestation (compared with the usual 18-22 weeks). Furthermore, the reason for performing early fetal echocardiography (EFEC) is that "the combined EFEC-NT (nuchal translucency) approach (11th-13th week) gives a 60-70% increase in detection rate for CHD. Combined EFE-NT analysis is also justified by the high CHD frequency in genetic syndromes and the similarity of anatomic relations between cardiac structures at 11-13 wks GA and those of the second trimester.” “The technical limits of EFEC are CRL < 50 mm, an increase of maternal Body mass index (BMI), unfavorable fetal position and a possible progression of cardiac disease especially in outflow obstructions. This means that the pregnant women should be informed about the limits of early screening and also recommended to have a further scan as from 18 weeks for a more complete diagnosis.”

Patients are referred for fetal echocardiography because of an abnormality of structure or rhythm noted on ultrasound examination or because the patient is in a high-risk group for fetal heart disease.  Treatment of the patient is facilitated by the early recognition of the exact nature of the cardiac problem in the fetus.  The correct diagnosis may be difficult because of fetal physiology, the effect on flow across defects and valves, inability to see the fetus for orientation reference, and inability to examine the fetus for clinical findings.  For these reasons, fetal echocardiography should be performed only by trained fetal echocardiographers.

The umbilical cord normally contains two arteries and one vein embedded in Wharton's jelly.The umbilical cord "achieves its final form by the 12th week of gestation". Initially during umbilical cord development, there are two umbilical arteries and two umbilical veins, in which the two veins (left and right) converge into one. Obliteration of the right umbilical vein by the end of the 6th week of gestation results in a single persisting left umbilical vein (Spurway et al, 2012). However, persistence of the right umbilical vein in the fetus is a variant of the intra-abdominal umbilical venous connection. The estimated prevalence of an intrahepatic persistent right umbilical vein is 1 per 786 births; which may be an underestimated calculation in populations that do not undergo targeted sonographic examinations. In addition, the variation in anatomy can be subtle (Lide et al, 2016).

Lide et al (2016) provided a comprehensive review of the current data surrounding an intra-hepatic persistent right umbilical vein in the fetus, including associated anomalies and outcomes, to aid practitioners in counseling and management of affected pregnancies.  These investigators performed a Medline, Embase, Cochrane Central Register of Controlled Trials, and Northern Light database search for articles reporting outcomes on prenatally diagnosed cases of a persistent right umbilical vein.  Each article was independently reviewed for eligibility by the investigators.  Thereafter, the data were extracted and validated independently by 3 investigators.  A total of 322 articles were retrieved, and 16 were included in this systematic review.  The overall prevalence of an intra-hepatic persistent right umbilical vein was found to be 212 per 166,548 (0.13 %).  Of the 240 cases of an intra-hepatic persistent right umbilical vein identified, 183 (76.3 %) were isolated.  The remaining cases had a co-existing abnormality, including 19 (7.9 %) cardiac, 9 (3.8 %) central nervous system, 15 (6.3 %) genito-urinary, 3 (1.3 %) genetic, and 17 (7 %) placental/cord (predominantly a single umbilical artery).  The authors concluded that a persistent right umbilical vein is commonly an isolated finding but may be associated with a co-existing cardiac defect in 8 % of cases.  Therefore, consideration should be given to fetal echocardiography in cases of a persistent right umbilical vein.

Canavan et al (2016) stated that a fetal persistent intrahepatic right umbilical vein has been linked to anomalies and genetic disorders but can be a normal variant.  These researchers conducted a retrospective review to determine other sonographic findings that can stratify fetuses for further evaluation.  A total of 313 fetuses had a persistent intra-hepatic right umbilical vein identified on 17- to 24-week sonography.  The outcome was any major congenital anomaly or an adverse neonatal outcome, which was defined as aneuploidy, fetal demise, or neonatal death.  A total of 217 patients (69.3 %) had a normal neonatal outcome; 69 patients (22.0 %) were lost to follow-up; 5 fetuses (2.1 %) had aneuploidy; 4 of the 5 had additional sonographic findings, and 1 had an isolated persistent intra-hepatic right umbilical vein; 24 fetuses had a major anomaly in association with the persistent right umbilical vein; 26 additional fetuses had soft sonographic markers associated with karyotypic abnormalities but were chromosomally normal.  Of those with adverse neonatal outcomes, 12 had a congenital heart defect (57 %).  An additional sonographic finding with a persistent intra-hepatic right umbilical vein was predictive of a congenital anomaly or an adverse neonatal outcome (p < 0.001), with a positive predictive value of 44.0 % (95 % confidence interval[ CI]: 30.0 % to 58.7 %).  An isolated persistent intra-hepatic right umbilical vein had a 0.4 % risk for a congenital anomaly or an adverse neonatal outcome.  The authors concluded that a persistent intra-hepatic right umbilical vein should prompt an extended anatomic survey and a fetal cardiac evaluation.  If the survey and cardiac anatomy are reassuring, no further follow-up is needed. If additional findings are identified, genetic counseling and invasive testing should be considered.

Kumar et al (2016) appraised the incidence and significance of persistent right umbilical vein (PRUV), the most common fetal venous aberration.  Based on a South Indian antenatal cohort, these researchers identified 23 cases of PRUV amongst 20,452 fetuses of consecutive pregnancies, from 2009 to 2014, yielding an incidence of 1 in 889 total births (0.11 %).  The median maternal age was 24 (inter-quartile range [IQR], 22 to 26) years, and median gestational age at diagnosis was 23 (IQR, 22 to 24) weeks.  Intra-hepatic drainage of PRUV was seen in 91.3 % cases.  In 3 cases (13 %), ductus venosus was absent.  In 52.2 % of the cases, additional major abnormalities were observed - predominantly cardiovascular (39.1 %).  The common minor marker was single umbilical artery (SUA; 13 %).  The karyotype was found to be normal in 6 cases (26 %) that underwent invasive testing.  When associated anomalies were inconsequential or absent, the post-natal outcome was good, which reflected in 60.9 % of these cases.  Fetal echocardiography was one of the keywords listed in this study.

In a prospective, observational study, Hill et al (1994) reviewed their experience with antenatal detection and subsequent neonatal outcome of fetuses with a persistent right umbilical vein.  A total of 33 cases of persistent right umbilical vein were detected during 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation.  Persistent right umbilical vein was detected at a rate of 1 per 476 obstetric ultrasound examinations; 6 of 33 (18.2 %) fetuses with a persistent right umbilical vein had additional important congenital malformations.  The authors concluded that careful 2nd- and 3rd-trimester ultrasound examinations can detect a persistent right umbilical vein.  When this particular anomaly is detected, a thorough fetal anatomic survey, including echocardiography, should be performed to rule out more serious congenital malformations.

Wolman et al (2002) conducted a prospective evaluation of the incidence and neonatal outcome of fetuses with persistent right umbilical vein.  This condition had traditionally been considered to be extremely rare and to be associated with a very poor neonatal prognosis, but later evidence has raised some doubts about the veracity of these contentions.  Between August 1995 and November 1998, a total of 8,950 low-risk patients were prospectively evaluated at 2 medical centers.  The sonographic diagnosis of a persistent right umbilical vein was made in a transverse section of the fetal abdomen when the portal vein was curved toward the stomach, and the fetal gall bladder was located medially to the umbilical vein.  Persistent right umbilical vein was detected in 17 fetuses during the study; 4 of them had additional malformations, of which 3 had been detected antenatally.  The authors established that the incidence of persistent right umbilical vein in a low-risk population was 1:526.  They believed that the sonographic finding of this anomaly was an indication for conducting targeted fetal sonography and echocardiography.  When the persistent right umbilical vein was connected to the portal system and other anomalies were ruled out, the prognosis can generally be expected to be favorable.

Martínez et al (2012) described the ultrasound findings, maternal and perinatal variables in cases with a prenatal diagnosis of persistence of right umbilical vein. This was a descriptive analysis of cases with prenatal diagnosis of persistence of right umbilical vein in the Fetal Medicine Unit, Department of Obstetrics and Gynecology, Hospital Universitario Severo Ochoa.  These investigators described ultrasound findings, maternal and perinatal variables.  They examined 9,198 fetuses and 6 cases (0.06 %) were diagnosis prenatally of persistent right umbilical vein, between 20 and 29 weeks of gestation.  The male/female ratio was 1/1.  Ductus venosus was presented in all cases; 2  fetuses (33 %) were proved to have other structural anomalies and their parents opted for termination of the pregnancy.  All cases had no chromosomal anomaly associated and after birth, neonatal developments were favorable.  The authors concluded that based on these findings and a literature review, after prenatal diagnosis of persistent right umbilical vein, an exhaustive morphological study, which included a fetal echocardiography, is mandatory in order to rule out other structural malformations.  Indication for fetal karyotype study has to be individualized considering persistence right umbilical vein type and other ultrasound findings.

A single umbilical artery (SUA) is present in 0.2 % to 0.6 % of live births, occurring more frequently in twins and in small for gestational age and premature infants.  In infants with SUA, there is an increased rate of chromosomal and other congenital anomalies.  Studies have shown that 20 % to 30 % of neonates with SUA had major structural anomalies, frequently involving multiple organs (Palazzi and Brandt, 2009; Thummala et al, 1998).  The most commonly affected organ is the heart.  Single umbilical artery is an isolated finding in the remaining 70 % to 80 % of infants.

Conception by in vitro fertilization (IVF) or intra-cytoplasmic sperm injection (ICSI) has been associated with an increased incidence of fetal heart defects.  A meta-analyses on the prevalence of birth defects in infants conceived following IVF and/or ICSI compared with spontaneously conceived infants reported a 30 % to 40 % increased risk of birth defects associated with IVF and/or ICSI (Hansen et al, 2005).  Researchers have reported that infants conceived with the use of IVF and/or ICSI have a 2-to-4-fold increase of heart malformations compared with naturally conceived infants.

Kurinczuk and Bower (1997) examined the prevalence of birth defects on 420 liveborn infants who were conceived after ICSI in Belgium compared with 100,454 liveborn infants in Western Australia delivered during the same period.  Infants born after ICSI were twice as likely as Western Australian infants to have a major birth defect [odds ratio (OR) 2.03, 95 % confidence interval (CI): 1.40 to 2.93); p = 0.0002] and nearly 50 % more likely to have a minor defect (OR 1.49 (0.48 to 4.66); p = 0.49).  Secondary data-led analyses found an excess of major cardiovascular defects (OR 3.99).

Koivurova et al (2002) evaluated the neonatal outcome and the prevalence of congenital malformations in children born after IVF in northern Finland in a population-based study with matched controls.  Children born after IVF (n = 304) in 1990 to1995 were compared with controls (n = 569), representing the general population in proportion of multiple births, randomly chosen from the Finnish Medical Birth Register (FMBR) and matched for sex, year of birth, area of residence, parity, maternal age and social class.  Plurality matched controls were randomly chosen from the FMBR and analyzed separately.  Additionally, IVF singletons were compared with singleton controls. The prevalence of heart malformations was four-fold in the IVF population than in the controls representing the general population (OR 4.0, 95 % CI: 1.4 to 11.7). 

Reefhuis et al (2009) analyzed data from the National Birth Defects Prevention Study, a population-based, multi-center, case-control study of birth defects.  Included were mothers of fetuses or live-born infants with a major birth defect (case infants) and mothers who had live-born infants who did not have a major birth defect (control infants), delivered during the period October 1997 to December 2003.  Mothers who reported IVF or ICSI use were compared with those who had unassisted conceptions.  Among singleton births, IVF or ICSI use was associated with septal heart defects (adjusted odds ratio [aOR] = 2.1, 95 % CI: 1.1 to 4.0).

As fetal heart disease is typically associated with structural abnormalities and consequent aberrant blood flow through the heart, it is necessary to perform Doppler studies and color flow mapping when such abnormalities are detected with 2D fetal echocardiography.

The American College of Obstetricians and Gynecologists' Committee Opinion on the treatment with selective serotonin reuptake inhibitors during pregnancy (ACOG, 2006) noted that paroxetine use among pregnant women and women planning pregnancy should be avoided, if possible.  Fetal echocardiography should be considered for women who were exposed to paroxetine in early pregnancy.

In a practice bulletin on screening for fetal chromosomal anomalies, ACOG (2007) has stated that patients who have a fetal nuchal translucency measurement of 3.5 mm or greater in the first trimester, despite a negative result on an aneuploidy screen, normal fetal chromosomes, or both, should be offered a targeted ultrasound examination, fetal echocardiogram, or both, because such fetuses are at a significant risk for non-chromosomal anomalies, including congenital heart defects, abdominal wall defects, diaphragmatic hernias, and genetic syndromes.

Twin-twin transfusion syndrome (TTTS) is a severe complication of monochorionic (1 placenta) twin pregnancies, characterized by the development of unbalanced chronic blood transfer from one twin, defined as donor twin, to the other, defined as recipient, through placental anastomoses.  If left untreated, TTTS is associated with very high peri-natal mortality and morbidity rates; and fetuses who survive are at risk of severe cardiac, neurological, and developmental disorders.

The American Society of Echocardiography's guidelines and standards for performance of the fetal echocardiogram (Rychik et al, 2004) stated that multiple gestation and suspicion of TTTS is an indication of fetal echocardiography.

Bahtiyar et al (2007) noted that congenital heart defects (CHDs) affect approximately 0.5 % of all neonates.  Recent literature points to a possible increase in the CHD prevalence among monochorionic/diamniotic (MC/DA) twin gestations.  These researchers hypothesized that MC/DA twin pregnancy is a risk factor for CHD.  A systematic review of all published English literature was conducted on MEDLINE (Ovid and PubMed) from January 2000 through April 2007 using the medical subject heading terms "congenital heart defect" and "monozygotic twins".  Four observational studies were included in the final analysis.  Published historical data were used for the population background risk of CHD.  Relative risk (RR) estimates with 95 % confidence intervals (CIs) were calculated by fixed and random effect models.  These investigators included a total of 40 fetuses with CHDs among 830 fetuses from MC/DA twin gestations.  Compared with the population, CHDs were significantly more prevalent in MC/DA twins regardless of the presence of TTTS (RR, 9.18; 95 % CI: 5.51 to 15.29; p < 0.001).  Monochorionic/diamniotic twin gestations affected by TTTS were more likely to be complicated by CHDs than those that did not have TTTS (RR, 2.78; 95 % CI: 1.03 to 7.52; p = 0.04).  Ventricular septal defects were the most frequent heart defects.  Pulmonary stenosis and atrial septal defects were significantly more prevalent in pregnancies complicated with TTTS.  The authors concluded that MC/DA twin gestation appears to be a risk factor for CHDs.  Conditions that lead to abnormal placentation may also contribute to abnormal heart development, especially in MC/DA twin pregnancies complicated with TTTS.  Fetal echocardiography may be considered for all MC/DA twin gestations because ventricular septal defects and pulmonary stenosis are the most common defects.

The Royal College of Obstetricians and Gynaecologists' clinical practice guidelines on "Management of monochorionic twin pregnancy" (RCOG, 2008) stated that a fetal echocardiographic assessment should be considered in the assessment of severe TTTS.

Pregnant Women Receiving Selective Serotonin Reuptake Inhibitors

Reefhuis and colleagues (2015) followed up on previously reported associations between peri-conceptional use of selective serotonin reuptake inhibitors (SSRIs) and specific birth defects using an expanded dataset from the National Birth Defects Prevention Study.  These researchers performed a Bayesian analysis combining results from independent published analyses with data from a multi-center population based case-control study of birth defects.  A total of 17,952 mothers of infants with birth defects and 9,857 mothers of infants without birth defects, identified through birth certificates or birth hospitals, with estimated dates of delivery between 1997 and 2009 were included in this analysis; exposures were citalopram, escitalopram, fluoxetine, paroxetine, or sertraline use in the month before through the 3rd month of pregnancy.  Posterior OR estimates were adjusted to account for maternal race/ethnicity, education, smoking, and pre-pregnancy obesity.  Main outcome measure was 14 birth defects categories that had associations with SSRIs reported in the literature.  Sertraline was the most commonly reported SSRI, but none of the 5 previously reported birth defects associations with sertraline was confirmed.  For 9 previously reported associations between maternal SSRI use and birth defect in infants, findings were consistent with no association.  High posterior ORs excluding the null value were observed for 5 birth defects with paroxetine (anencephaly 3.2, 95 % CI: 1.6 to 6.2; atrial septal defects 1.8, 95 % CI: 1.1 to 3.0; right ventricular outflow tract obstruction defects 2.4, 95 % CI: 1.4 to 3.9; gastroschisis 2.5, 95 % CI: 1.2 to 4.8; and omphalocele 3.5, 95 % CI: 1.3 to 8.0) and for 2 defects with fluoxetine (right ventricular outflow tract obstruction defects 2.0, 95 % CI: 1.4 to 3.1 and craniosynostosis 1.9, 95 % CI: 1.1 to 3.0).  The authors concluded that these data provided reassuring evidence for some SSRIs; but suggested that some birth defects occurred 2 to 3.5 times more frequently among the infants of women treated with paroxetine or fluoxetine early in pregnancy.

A 2015 study by the Centers for Disease Control and Prevention (CDC) used new data to examine previous reported links between use of specific SSRIs medications just before or during early pregnancy and the occurrence of certain birth defects.  Researchers looked at links with 5 different SSRI medications: citalopram, escitalopram, fluoxetine, paroxetine, and sertraline.  Although the new data confirmed the risks seen with paroxetine, it did not appear to suggest that the risk is across the board with all SSRIs.  Therefore, fetal echocardiography is still recommended for women exposed to paroxetine, but there doesn’t seem to be enough evidence to recommend coverage of fetal echocardiograms for all pregnant members receiving any SSRI.  The study concluded that despite the increased risks for certain birth defects from some SSRIs found in this study, the actual risk for a birth defect among babies born to women taking one of these medications is still very low.  Because these specific types of birth defects are rare, even doubling the risk still results in a low absolute risk.  For example, the risks for heart defects with obstruction of the right ventricular outflow tract could increase from 10 per 10,000 births to about 24 per 10,000 births among babies of women who are treated with paroxetine early in pregnancy. 

Fetal Magnetocardiography

Fetal magnetocardiography (fMCG) is a new, non-invasive technique used to monitor the spontaneous electrophysiological activity of the fetal heart.  Hrtankova and associates (2015) reviewed the evidence on the clinical value of fMCG.  These investigators performed an analysis of the literature using database search engines PubMed, and SCOPE in field of fMCG.  Compared to cardiotocography and fetal electrocardiography, fMCG is a more effective method with a higher resolution.  The signal obtained from the fetal heart is sufficiently precise and the quality allows an assessment of PQRST complex alterations, and to detect fetal arrhythmia.  Thanks to early diagnosis of fetal arrhythmia, there is the possibility for appropriate therapeutic intervention and the reduction of unexplained fetal death in late gestation.  These investigators also noted that fMCG with high temporal resolution also increased the level of clinical trials that recorded fetal heart rate (FHR) variability.  According to the latest theories, FHR variability is a possible indicator of fetal status and enabled the study of the fetal autonomic nervous system indirectly. The authors concluded that fMCG is an experimental method that requires expensive equipment; it has yet to be shown in the future if this method will get any application in clinical practice.

Eswaran and colleagues (2017) stated that fMCG provides the requisite precision for diagnostic measurement of electrophysiological events in the fetal heart.  Despite its significant benefits, this technique with current cryogenic based sensors has been limited to few centers, due to high cost of maintenance.  In this study, these researchers demonstrated that a less expensive non-cryogenic alternative, optically pumped magnetometers, can provide similar electrophysiological and quantitative characteristics when subjected to direct comparison with the current technology.  They concluded that further research can potentially increase its clinical use for fMCG.

Furthermore, an UpToDate review on “Overview of the general approach to diagnosis and treatment of fetal arrhythmias” (Levine and Alexander, 2017) states that “Magnetocardiography shifts the electrical signals into an evoked magnetic signal that can be processed to create a beat-to-beat magnetocardiogram that looks much like a traditional electrocardiogram (ECG).  Continuous recordings can be performed for relatively sustained periods and have permitted elegant demonstration of arrhythmia onset/offset and more direct observation of mechanisms.  The equipment is not widely available, requires careful shielding and requires skilled technical support, so the technology remains investigational”.

Appendix

Documentation Requirements for Fetal Echocardiography

According to guidelines from the American Institute for Ultrasound in Medicine (AIUM), fetal echocardiography should include the following cardiac images:

• Aortic arch;
• Ductal arch;
• Four-chamber view;
• Inferior vena cava;
• Left ventricular outflow tract;
• Right ventricular outflow tract;
• Short-axis views (“low” for ventricles and “high” for outflow tracts);
• Superior vena cava; and
• Three-vessel and trachea view.

According to the 2013 AIUM's practice parameter for the "Performance of Fetal Echocardiography", indications for fetal echocardiography are often based on a variety of parental and fetal risk factors for congenital heart disease.  However, most cases are not associated with known risk factors.  Common indications for a detailed scan of the fetal heart include but are not limited to:

Maternal Indications Associated with Congenital Heart Disease

• Autoimmune antibodies [anti-Ro (SSA)/anti-La (SSB)]
• Familial inherited disorders (e.g., 22q11.2 deletion syndrome)
• In-vitro fertilization
• Metabolic disease (e.g., diabetes mellitus and phenylketonuria)
• Teratogen exposure (e.g., lithium and retinoids)

Fetal Indications

• Abnormal cardiac screening examination
• Abnormal heart rate or rhythm
• Fetal chromosomal anomaly
• Extra-cardiac anomaly
• First-degree relative of a fetus with congenital heart disease
• Hydrops
• Increased nuchal translucency
• Monochorionic twins

This AIUM (2013) practice parameter was published in conjunction with the American College of Obstetricians and Gynecologists (ACOG), and the Society for Maternal-Fetal Medicine (SMFM), and the American Society of Echocardiography (ASE).  Furthermore, this practice parameter was endorsed by the American College of Radiology (ACR).

Source: AIUM Practice Parameter – Fetal Echocardiography (2013).

The above policy is based on the following references: