RDCS Fetal Echo flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fetal cardiac axis

The angle between the ventricular septum and the midline, normally about 45 degrees (range 25-65); deviation suggests cardiac malposition, a conotruncal anomaly, or an extracardiac mass.

Moderator band

A muscular ridge within the right ventricle near the apex, seen in the four-chamber view; its presence identifies the morphologic right ventricle.

Foramen ovale flap

The septum primum, which lies on the left atrial side of the atrial septum and normally opens right-to-left, directing oxygenated umbilical venous blood into the left heart.

Tricuspid valve offset

The tricuspid valve inserts slightly more apical than the mitral valve; a difference under about 8 mm is normal, while greater displacement suggests Ebstein anomaly.

Cardiothoracic area ratio

Fetal heart area divided by thoracic area in the four-chamber view, normally about 0.25-0.35; values above 0.35 indicate cardiomegaly.

Three-vessel view

A transverse plane above the four-chamber view showing pulmonary artery, aorta, and superior vena cava left to right, normally decreasing in size in that order.

Ductal arch shape

In the sagittal view the ductal arch resembles a hockey stick, formed by the pulmonary artery continuing into the descending aorta, lying anterior to the aortic arch.

Atrioventricular septal defect

Absence of the central atrial and ventricular septum with a common atrioventricular valve, seen as a single crux in the four-chamber view; strongly associated with trisomy 21.

Hypoplastic left heart syndrome

A markedly small left ventricle with mitral and aortic atresia or stenosis; systemic flow is ductal with retrograde aortic arch flow, and ductal closure is fatal.

Tetralogy of Fallot

Ventricular septal defect with overriding aorta, pulmonary outflow obstruction, and right ventricular hypertrophy; in fetuses the key findings are the defect, aortic override, and small pulmonary artery.

Transposition of great arteries

The aorta arises anteriorly from the right ventricle and the pulmonary artery from the left ventricle, producing parallel rather than crossing great vessels on outflow views.

Cardiac rhabdomyoma

The most common fetal cardiac tumor, appearing as a solid homogeneous ventricular mass that is often septal or multiple and strongly associated with tuberous sclerosis.

Ebstein anomaly

Apical displacement of the tricuspid septal leaflet with atrialization of the right ventricle, severe tricuspid regurgitation, and cardiomegaly; associated with lithium exposure and arrhythmia.

Double outlet right ventricle

Both great arteries arise predominantly from the right ventricle and a ventricular septal defect is always present; the relationship of the vessels determines the subtype.

Normal fetal heart rate

Between about 110 and 160 beats per minute in the second and third trimester; below 110 is bradycardia and above 180 is tachycardia.

Supraventricular tachycardia

A fetal tachycardia of about 220-260 beats per minute with 1:1 atrioventricular conduction and abrupt onset; a common cause of hydrops if sustained.

Atrial flutter

Atrial rates of 300-500 beats per minute with variable atrioventricular block, producing a slower irregular ventricular rate; often associated with hydrops and treated transplacentally.

Myocardial performance index

The Tei index equals isovolumetric contraction plus relaxation time divided by ejection time; normally about 0.35-0.5 and raised with global systolic or diastolic dysfunction.

Ductus venosus a-wave

Absent or reversed a-wave flow during atrial systole reflects raised atrial pressure and acidemia in growth-restricted fetuses; normally the a-wave is forward.

Combined cardiac output

The sum of right and left ventricular outputs, roughly 450 mL/kg/min in the fetus, with the right ventricle contributing about 55-60 percent.

Cerebroplacental ratio

Middle cerebral artery pulsatility index divided by umbilical artery pulsatility index; a value below 1 suggests brain sparing and redistribution in placental insufficiency.

ALARA principle

As low as reasonably achievable: use the lowest acoustic output and shortest dwell time needed for diagnosis, especially during spectral Doppler in the first trimester.

Thermal index

An estimate of temperature rise from absorbed ultrasound; TIB applies when bone is in the beam and TIS for soft tissue, and values should generally stay at or below 1.

Mechanical index

Peak rarefactional pressure divided by the square root of frequency; it estimates cavitation risk and is displayed, though risk is low in the gasless fetus.

Nyquist limit

Half the pulse repetition frequency; velocities exceeding it alias, so raise the scale or PRF, shift the baseline, or change transducer frequency to avoid misinterpretation.

Axial resolution

Determined by spatial pulse length divided by two; higher transmit frequency shortens the pulse and improves axial resolution but reduces penetration in obese patients.

Frame rate factors

Frame rate rises with a narrower sector, shallower depth, a single focal zone, and reduced line density; fetal echocardiography needs at least 30-60 frames per second.

Fetal echo indications

Family history of congenital heart disease, maternal diabetes, teratogen exposure, aneuploidy, abnormal four-chamber view, arrhythmia, hydrops, or monochorionic twin complications.

Optimal timing fetal echo

Transabdominal fetal echocardiography is best performed between 18 and 24 weeks, when cardiac structures are large enough while acoustic windows remain favorable.

Anti-Ro/SSA surveillance

Maternal anti-Ro or anti-La antibodies can cause congenital complete heart block; serial fetal echocardiograms with PR interval measurement are done about weekly from 16 to 28 weeks.

Maternal diabetes effect

Infants of diabetic mothers risk hypertrophic cardiomyopathy with asymmetric septal thickening, plus other cardiac anomalies; risk is worse with poor periconceptional glycemic control.

Ductal constriction causes

Third-trimester NSAID or indomethacin exposure can constrict the ductus arteriosus, causing right ventricular dilation, tricuspid regurgitation, and hydrops; serial echoes are required.