Catherine Fredouille, Jean-Eric Develay-Morice and Claudio Lombardi
CHAPTER CONTENTS
Technical points to remember
Key points to remember
Pathologies to remember
Morphological points to remember
Conclusion
In order to examine the fetal heart efficiently, certain rules must be followed.
Technical points to remember
The technical rules for obtaining an excellent image are:
• An ideal exposition in the zone of interest due to:
– appropriate windows to the fetal position
– a perpendicular approach to the zones of interest
– an extensive use of the zoom, but also:
• An optimal use of settings with:
– a specific pre-adjustment, specifically for the heart
– a constant modification of the gain
– appropriate focal zones.
The use of Doppler, which is limited to certain indications, imposes the use of a “box” of minimal size.
• First-trimester study has specific technical requirement
Throughout our examination we acquire—and pay special attention in choosing—the highest quality images. After the examination, these will stand as proof of normality or pathology of the heart, even when interpreted by other operators and specialists.
Key points to remember
By understanding ultrasound settings (US) we can use them to our advantage. By their correct use, with constant attention to acquiring excellent views, we can avoid many of the pitfalls we are confronted with in these examinations. Thus while acquiring our views we can use the three steps and ten key points methodology to verify if a fetal heart is normal or not.
The first step verifies position with:
• Point 1: laterality and position of the organs and vessels.
• Point 2: the axis of the heart should normally be at an angle of around 45°.
This is determined by carrying out the “elevator” from the TAD to the “optimal” four-chamber view along two vessels, the aorta and the IVC.
The second step verifies the inlet and is only accomplished using the “optimal” four-chamber view defined by three reference marks: the apex and the two inferior pulmonary veins (PVs). The presence of one or two complete ribs, depending on the approach of the view, allows us to ensure the axis of the image.
The following must appear in this view:
• Point 3: the heart, with its apex to the left, is attached to the lungs by the two inferior PVs.
• Point 4: there are four chambers.
• Point 5: contractile, balanced, and concordant.
• Point 6: the crux of the heart should show an offsetting of the atrioventricular valves.
The third step verifies the outlet and necessitates several complementary views to allow us to visualize:
• Point 7: two outlet chambers separated by an aligned outlet septum.
• Point 8: two conjoined vessels which cross over and are superimposed.
• Point 9: balanced and concordant outflow tracts.
• Point 10: a hooked arch arising at the center of the heart and giving rise to the three vessels of the neck.
The examination of the fetal heart begins at the level of the TAD view and goes up through the “elevator” towards the “optimal” four-chamber view.
You must verify that:
• The stomach, the aorta, and the apex of the heart are on the same left side.
• The axis of the heart is at an angle of around 45°.
• The outlet vessels must be balanced (in pathology, if one, for instance has a large diameter, the other will have a small one).
Pathologies to remember
Through this method, the discovery of a pathology allows us to “classify” it into one of the different families and thus place it into the context of its associated pathologies or complications.
The Position Anomalies
Position anomalies are more frequently related to the visceroatrial heterotaxias, which have a normal karyotype.
The Inlet Anomalies
Depending on the anomaly, we observe:
• The pathologies of symmetry: a hypoplastic LV is more frequent than a hypoplastic RV, tricuspid atresia, and Ebstein disease.
• The pathologies of the AVSD spectrum mainly touch the crux of the heart, one of the major warning signs of trisomy 21, but of other pathologies as well.
Outlet Anomalies
Outlet anomalies fall into two principal categories:
• Complete transposition of the great vessels, as a rule seen in isolation in an otherwise normal fetus. This is one of the most important diagnoses not to overlook.
• Frequent conotruncal cardiopathies (CTCs). These are present in numerous chromosomal anomalies, but also in polymalformation syndromes. We know of the preferred relationship that certain CTCs have with 22q11 chromosomal deletion (IAA, or PA with OS, and MAPCA).
In these pathologies of inlet and outlet, there can exist (at the same time) flow anomalies which translate into asymmetries in the size of the chambers or the diameters of the great vessels.
Morphological points to remember
The morphological examination should be complete, but still oriented by the type of cardiopathy or the gravity of certain syndromes. Certain associated elements such as IURG, amniotic fluid anomalies (oligo- or hydramnios), and malformations of the face or extremities should make us very cautious.
Investigating for certain particular anomalies should be attempted, for instance in the case of semicircular canals, an important element of the CHARGE association, which is sometimes identifiable by the second trimester.
The right course to take varies depending on what we are faced with. The prognosis can be poor when criteria for polymalformation are found even when associated with minor cardiopathy. The outcome is very different when we see a more serious cardiopathy, but where the fetus is found to have a known normal karyotype and a totally reassuring extracardiac US examination.
In the absence of all associated pathologies detectable by systematic karyotype, including the detailed morphological study, the precise diagnosis of the type of cardiopathy and its prognosis becomes essential and is the priority. This then becomes the domain of the pediatric cardiology team.
Any isolated cardiopathy will be given to the pediatric cardiologist to make a precise diagnosis and prognosis which will guide the pre-, per-, and postnatal approach.
Because of legislation and the advice of a multi-disciplinary center for prenatal diagnosis combined with parental wishes, a medical termination of pregnancy might be proposed when we are faced with certain polymalformations or complex cardiopathies that offer no hope.
Faced with a curable cardiopathy, the pediatric cardiology team takes charge of the follow-up of the patient at birth.
Conclusion
Throughout this book our goal has been to approach the examination of the fetal heart in a simple and practical way. This will allow ultrasound specialists and operators to perform these examination with less apprehension and more confidence. Moreover it will ensure the best possible performance and the clearest, most interpretable results.
We only find what we look for.
We only look for what we know.
We only know what we understand.