RDCS Fetal Echo key terms

A transverse cross-section of the fetal thorax showing both atria, both ventricles, the atrioventricular valves, and the atrial and ventricular septa; an abnormality here is the usual trigger for detailed cardiac evaluation.

The direction the fetal heart points relative to the chest midline, normally toward the left anterior chest at roughly 45 degrees; deviation suggests malposition, isomerism, or a space-occupying cardiac mass.

The central region where the atrial and ventricular septa meet the atrioventricular valve plane; normally the septa align in a straight line, and offset or a gap signals an atrioventricular septal defect.

The thin mobile membrane of the atrial septum that normally bows into the left atrium to form the foramen ovale; it is the structure assessed when foramen ovale restriction or premature closure is suspected.

A prominent muscular ridge near the apex of the morphologic right ventricle; its presence helps identify ventricular situs and distinguish the right ventricle from the smoother-walled left ventricle.

The normal arrangement in which the tricuspid valve inserts slightly closer to the cardiac apex than the mitral valve; loss or reversal of this offset suggests an atrioventricular septal defect or Ebstein anomaly.

The area of the fetal heart divided by the area of the chest on a four-chamber view, normally under about one third; enlargement suggests cardiomegaly from volume load, cardiomyopathy, or arrhythmia.

A five-chamber or long-axis view in which the left ventricle is seen continuous with the ascending aorta and aortic valve; it confirms ventriculoarterial connection and allows measurement of the aortic root.

A sagittal view in which the pulmonary artery continues into the descending aorta through the ductus arteriosus, producing a hockey-stick curve; its size and flow direction reflect right heart output.

A sagittal view showing the ascending aorta, transverse arch, and descending aorta with their head and neck branches, described as a candy cane; it is used to judge arch sidedness and continuity.

An upper mediastinal transverse view showing the main pulmonary artery, aorta, and superior vena cava in a V shape to the left of the trachea; abnormal arrangement reveals arch anomalies and conotruncal defects.

A small bright spot within ventricular myocardium, most often the left ventricle, caused by calcified papillary muscle; frequently a benign variant but sometimes regarded as a soft marker for aneuploidy.

The normal left-right arrangement of thoracic and abdominal organs, with the stomach on the left, liver on the right, and cardiac apex pointing left; established by assessing stomach, aorta, and heart position together.

Severe underdevelopment of the left ventricle, mitral valve, and aortic valve, with a tiny or absent ascending aorta; systemic blood flow depends on the ductus arteriosus, making the lesion ductal-dependent after birth.

A conotruncal defect combining a ventricular septal defect, an overriding aorta, right ventricular outflow obstruction, and right ventricular hypertrophy; prenatally the obstruction may be mild and the heart only slightly enlarged.

A deficiency of the central cardiac crux with a common atrioventricular junction and septal defect, strongly linked to trisomy 21; the four-chamber view shows a single valve plane crossing the septum.

Ventriculoarterial discordance in which the aorta arises from the right ventricle and the pulmonary artery from the left; the four-chamber view may look normal, so outflow tract views are essential for detection.

Downward displacement of the septal tricuspid leaflet into the right ventricle, atrializing part of the ventricle; severe cases cause massive cardiomegaly, tricuspid regurgitation, arrhythmia, and hydrops.

An aortic arch that passes to the right of the trachea, often forming a U shape with the ductus on the three-vessel view; it is associated with conotruncal defects and with a vascular ring.

A conotruncal anomaly in which both great arteries arise predominantly from the right ventricle; outflow views show side-by-side or parallel vessels together with a ventricular septal defect.

The most common fetal cardiac tumor, appearing as a well-circumscribed echogenic mass in a ventricle or the septum; it is strongly associated with tuberous sclerosis and may obstruct flow or provoke arrhythmia.

Disordered left-right organization of the organs, often with complex congenital heart disease, interrupted inferior vena cava, and abnormal spleen; suspected when stomach, aorta, and cardiac positions disagree.

The number of cardiac beats per minute, normally about 110 to 160 in mid-gestation; measured with M-mode or Doppler and used to identify bradycardia, tachycardia, or an irregular rhythm.

A Doppler-derived ratio of combined isovolumic contraction and relaxation time to ejection time, reflecting global ventricular performance; it can be calculated for one ventricle or for both together.

The atrial contraction wave in ductus venosus Doppler that normally remains forward; absent or reversed a-wave flow indicates raised right heart pressures or impaired myocardial function and increases aneuploidy and cardiac risk.

Third-degree atrioventricular block with complete dissociation of atrial and ventricular activity; the fetal rate is slow and fixed, often related to maternal autoantibodies or structural heart disease.

An early atrial beat that produces an irregular ventricular rhythm and is usually benign; frequent or blocked beats can progress to tachyarrhythmia and warrant follow-up study.

A fast, regular fetal rhythm typically exceeding 220 beats per minute that arises above the ventricles; sustained episodes can cause hydrops and often require transplacental antiarrhythmic therapy.

The sum of right and left ventricular outputs, each calculated from valve diameter and the Doppler velocity time integral; it reflects fetal circulatory adaptation and response to placental resistance.

Fluid accumulation in at least two fetal compartments, such as ascites, pleural effusion, and skin edema; cardiac causes include arrhythmia, structural defects, and high-output failure from anemia.

An on-screen estimate of heating potential from absorbed acoustic energy, expressed as the ratio of attenuated power to the power needed to raise tissue temperature one degree; it should be kept as low as practical.

An on-screen indicator of cavitation potential, calculated from peak rarefactional pressure divided by the square root of frequency; it is particularly relevant for gas-containing tissues and first-trimester exposures.

The practice of keeping acoustic exposure as low as reasonably achievable by limiting output power, dwell time, and unnecessary Doppler; especially important in early pregnancy and when imaging embryonic tissue.

How rapidly successive image frames are acquired, governed mainly by frame rate; high frame rates are needed to capture fast fetal cardiac motion and to time cardiac events accurately.

The highest Doppler frequency shift that can be displayed unambiguously at a given pulse repetition frequency; exceeding it produces aliasing, seen as color wrap-around or reversed spectral peaks.

The angle between the ultrasound beam and the direction of blood flow; Doppler measurements are most accurate near zero degrees and become unreliable as the angle approaches 90 degrees.

A display that superimposes mean blood velocity and direction on the two-dimensional image; it helps confirm flow across valves and septa but is limited by aliasing and beam angle.

Assessment at about 11 to 14 weeks of cardiac position, four-chamber view, and outflow tracts, often combined with nuchal translucency, tricuspid regurgitation, and ductus venosus Doppler.

A clinical reason to perform a detailed fetal cardiac study, such as suspected anomaly, family history, maternal diabetes, teratogen exposure, aneuploidy risk, or abnormal screening markers.

A comprehensive study including cardiac situs and axis, four-chamber and outflow views, arch views, and M-mode and Doppler assessment of function and rhythm, usually performed by a specialist.