History of prenatal cardiology in the world and in Poland

The beginnings of fetal echocardiography

With the swift progress of technology after the Second World War and the consequent development of the first ultrasound machine, it was only a matter of time before it was used in fetal medicine. In 1958 Ian Donald revolutionised obstetric diagnostics by publishing in “Lancet” his work titled “Investigation of abdominal masses by pulsed ultrasound” [1]. It gave a starting point to the ongoing investigation of newer techniques. The earliest works done on fetal imaging included those done in 1972 by Stuart Campbell and in 1974 by Brian Trudinger, who described detection of major cardiac deformities and arrhythmias [2].
In the 1980s fetal cardiology became a reality. Advances made in ultrasound machine technology enabled fetal echocardiography examinations to be more precise and accurate, leading to an increased in prenatally detected congenital heart defects (CHD) [3]. Additionally, better imaging quality, evolving from M-mode into two-dimensional (2D) imaging and greater universality of ultrasound machines, led to the possibility of including structural cardiac screening in the fetal anatomy protocol, and at Guy’s Hospital in London, Lindsey Allan, Tony Tynan, et al. developed standardised protocols for cardiac screening with planes, the most important being the four-chamber view, which should be obtained in every examination [4, 5].
The works on prenatal cardiology were not limited to London. At the same time, in the USA, Kleinman et al. [6-9] were also describing fetal abnormalities with special interest in fetal arrhythmias and their treatment via the placenta. At this point in history, prenatal cardiology became an integral part of perinatal care, which involved numerous specialties, including obstetricians, paediatric cardiologists, neonatologists, surgeons, and radiologists.
Following the development of use of the Doppler effect and the invention of colour Doppler in the late 1980s and spectral Doppler in the early 1990s , the assessment of intracardiac, arterial, and venous flow patterns became a reality, leading to the possibility of evaluation of not only structures, but also functional abnormalities [10].
Moreover, Doppler cardiography also impacted the assessment of fetal well-being. Huhta et al. [11, 12] in 2005 developed the “Cardiovascular Profile Score” (CVPS) system, which described cardiovascular efficiency using flow patterns in the umbilical artery and vein, flow pattern in the ductus venosus, cardiac function (RV/LF shortening fraction, flow pattern through mitral and tricuspid valve – presence of a regurgitation, monophasic flow), presence of fetal hydrops (ascites, hydrothorax, or skin oedema), and heart size (using HA/CA measurement) [13, 14].
With further progress of the technology, the cardiac screening could be extended into the 1st trimester anatomy scan, done up to 13 + 6 weeks of gestation (Figure 1).

First-trimester fetal echocardiography examination

Initially, the first-trimester examination was only possible in our imagination, due to the difficulty of imaging such a small structure. The breakthrough happened in mid-1980s, when high-frequency transvaginal ultrasound probes were invented. Primarily, it was used to determine the existence of the fetal heartbeat in the 6-7th week of gestation, but it provided the basics for further studies [15].
From this point, researchers began to describe cardiac anatomy in early pregnancy fetuses from 11 + 0 to 13 + 6 weeks of gestation. The planes that could be assessed were the same ones as done earlier in a routine second-trimester scan, and at the beginning of the 1990s Gembruch et al. [16, 17] reported successful fetal heart assessment in 11-13 weeks of gestation. They were able to visualise the heart in four-chamber view and great-vessel view. Later, they also assessed not only the anatomical structure of the heart, but also its haemodynamics.
Afterwards, Nicolaides discovered that there is a correlation between nuchal translucency (NT) measured at 11-13 weeks of gestation and the occurrence of congenital heart defects in chromosomally abnormal fetuses [18].
Further progress led to cardiac evaluation by three-dimensional (3D), four-dimensional (4D), and spatiotemporal image correlation (STIC) [19], which improved the imaging quality. All the above resulted in the inclusion of fetal heart scanning in the International Society of Ultrasound in Obstetrics and Gynaecology (ISUOG) guidelines in 2006 [20, 21].
Guidelines were published not only from the ISUOG but also from other societies such as the American Heart Association (AHA) [22], the American Society of Echocardiography (ASE) [23], and the Association for European Paediatric Cardiology/Fetal Cardiology Working Group (AEPC/FCWG) [24].

Prenatal cardiology in Poland

In the late 20th century prenatal cardiology was also developing in Poland. The earliest articles were published in the 1980s and 1990s; however, systematic fetal cardiac assessment was not yet standard practice. In the 1990s Polish doctors started studying fetal echocardiography abroad and then implemented it into Polish standards. In 2004 Professors Maria Respondek-Liberska (trained in USA) and Joanna Szymkiewicz-Dangel (trained in the UK) initiated the Polish National Registry for Fetal Cardiac Pathology under the Ministry of Health [25, 26]. This unique data registry collected data nationwide on prenatally diagnosed CHD. As well as the registry, the cardio-prenatal program was implemented. Its aim was to simplify referral pathways and improve perinatal and neonatal cardiac care and to check how many fetal cardiac centres in Poland would have over 100 fetal cardiac defects per year (in the years 2004-2024 there were 4 such centres of so-called type C), based on their input into the registry. There is also a certification system; to gain certification, one must take part in a prenatal echocardiography workshop, one-week training in a Department of Prenatal Cardiology, and submit at least 10 abnormal cases with freeze-frames or cine-loops to the Polish National Registry for Fetal Cardiac Pathology – there are now 58 doctors with such certification in Poland. Later, in 2016, the Polish Prenatal Cardiology Society was established, and yearly fetal cardiac conferences have been organised in Łódź since 1997. In addition to the Polish Prenatal Society, there is the Fetal Cardiology Section of the Polish Ultrasound Society; there is also a group of obstetricians in the Polish Obstetrics and Gynaecology Society.
A fetus with accurate prenatal diagnosis can even be invasively treated prenatally in some rare, selected cases [27]. However, in most cases, prenatal cardiology is not only the diagnosis, but it is also used for the planning of future treatment. With the cooperation of the obstetrician, prenatal cardiologist, paediatric cardiologist, and cardiothoracic surgeon, the predicted outcome of newborns with CHD born with CHD has improved [28-30]. The prenatal diagnosis and accurate classification of the defect are crucial for the neonate’s outcome [30]. Neonates with adequate prenatal diagnosis can be treated soon after the birth, via cardiothoracic surgery, without delay. As an example, fetuses with HLHS can be named, because in recent years there has been an improvement in our tertiary centre in neonates surviving the Norwood procedure, nowadays reaching approximately 90% [31-33].
As time passes, there is still debate over who should perform the prenatal examination of the heart. There are a lot of arguments on both sides – whether it should be the obstetrician or paediatric cardiologist – but the answer is simple, it should be the person competent in fetal echocardiography, regardless of specialisation. In the future, it might evolve into a separate subspecialty, but for now we should encourage anyone with an inclination to perform such examination.
Nowadays, a rapid decline in the number of births in Poland can be observed. However, the number of congenital heart defects has remained at the same level. As the number of pregnancies acquired via IVF grows, the number of older women becoming pregnant increases, and the number of gravidas with other illnesses – such as pregestational diabetes – that are related to the origin of CHD, and consequently the number of fetuses requiring fetal echocardiography examination, also increases. Because fetal a echocardiography examination can predict some of the complications encountered in the neonatal period [34-36], recent recommendations of the Polish Prenatal Cardiology Association have become the first in the world recommend performing a fetal echocardiography examination not only in the 2nd trimester, but also in the 3rd [37].

Conclusions

The beginnings of prenatal cardiology are directly linked to the technological advances of the 20th century. From simple anatomical scanning, nowadays it includes complex perinatological care with the fetus recognised as a patient who can be diagnosed and treated. Fetal echocardiography is not restricted to the second-trimester scan but can be also carried out in the first trimester of pregnancy with great accuracy. It may also be carried out in the third trimester, opening a next new field of “prebirth cardiology”. The continued evolution of the field will depend on maintaining multidisciplinary cooperation and strengthening training in tertiary centres.

Disclosures

Ethical considerations: none.
This research received no external funding.
The authors declare no conflict of interest.

References