fetal heart abnormalities

the fetal circulation consists of 3 “shortcuts”:

1. ductus venosus

2. foramen ovale

3. ductus arteriosus

oxygen rich blood from the placenta is delivered to the IVC via the:

umbilical vein and ductus venosus

the IVC also receives blood from the:

hepatic veins but it is not as oxygen rich bc it is processed by the liver

bc the fetal lungs are not functional, most of the blood will bypass the R ventricle and is shunted from the R atrium to the L atrium via the:

foramen ovale

foramen ovale

opening between the R and L atria

most of the blood will be shunted from the pulmonary artery and into the aorta via the:

ductus ateriosus and will not travel into the non-functioning lungs

within 10-15 hrs after birth, what happens to the ductus arteriosus?

it constricts and becomes the ligamentum arteirosum

within 10-15 hrs after birth, what happens to the foramen ovale?

it closes and becomes the fossa ovalis

within 10-15 hrs after birth, what happens to the ductus venosus?

it constricts and becomes the ligamentum venosum

normal fetal thorax:

fetal heart should occupy approx. 1/3 of the thoracic cavity

normal fetal heart:

• L atrium is closest to the spine

• apex of the heart points 45 degrees to the left anterior chest wall

left ventricular outflow tract (LVOT)

identifies the origin of the aorta arising from the L ventricle

right ventricular outflow tract (RVOT)

identifies the origin of the pulmonary trunk arising from the R ventricle

sonographic appearance of the aortic arch:

“candy cane” appearance

sonographic appearance of the ductal arch (ductus arteriosus):

“hockey stick” appearance

risk factors for congenital heart disease (CHD):

• family hx

• maternal DM

• teratogen exposure

• chromosome abnormalities

• maternal vascular disease

types of structural cardiac malformations:

• ventricular septal defect (VSD)

• arterial septal defect (ASD)

ventricular septal defect (VSD)

• most common defect postnatally

• caused by incomplete closure of the intraventricular foramen

• most teratogen - assoc. fetal defect

sonographic appearance of a ventricular septal defect:

• demonstration of an opening between the ventricles on the 4-chamber view

• bidirectional flow demonstrated with color doppler

atrial septal defect (ASD)

• any abnormal opening between the atria

• associated with a variety of cardiac and chromosomal abnormalities

sonographic appearance of an atrial septal defect:

• relies on demonstration of echo dropout at the level of the atrial septum

• prenatal diagnosis unlikely due to patent foramen ovale

hypoplastic right heart syndrome

occurs due to pulmonary atresia with an intact interventricular septum

sonographic appearance of hypoplastic right heart syndrome:

• absent or very small R ventricle on 4-chamber view

• absent or small pulmonary artery

hypoplastic left heart syndrome

small L ventricle due to decreased blood flow into or out of the L ventricle

sonographic appearance of hypoplastic left heart syndrome:

• absent or very small L ventricle

• hypoplastic or atretic mitral valve and aorta

transposition of the great arteries (TGA)

• origins of the great vessels are transposed

• aorta arises from the R ventricle

• pulmonary artery arises from the L ventricle

sonographic appearance of TGA:

• correct L-R orientation is a must

• images of outflow tracts demonstrate anomalous origin

truncus arteriosus

• single large vessel arises from the base of the heart

• VSD usually present

double outlet right ventricle

pulmonary artery and aorta arise from the R ventricle

double outlet right ventricle is associated with:

• other cardiac defects

• maternal diabetes

• maternal alcohol consumption

ectopia cordis

all or part of the heart is located outside of the chest cavity

ectopia cordis is associated with:

• intracardiac anomalies

• omphalocele

tetralogy of fallout

rare complex congenital heart defect that changes the normal flow of blood through the heart

tetralogy of fallout involves 4 heart defects:

1. ventricular septal defect

2. pulmonary stenosis

3. right ventricular hypertrophy

4. an overriding aorta

pulmonary stenosis

• narrowing of the pulmonary valve and the passage from the R ventricle to the pulmonary artery

• pulmonary valve cannot full open

• causes heart to work harder to pump blood through the valve

right ventricular hypertrophy

• the muscle of the R ventricle is thicker than usual

• occurs bc the heart has to work harder than normal to move blood through the narrowed pulmonary valve

overriding aorta

• the aorta is located between the L and R ventricles, directly over the VSD

• results in some oxygen poor blood from the R ventricle flowing directly into the aorta instead of into the pulmonary artery

Ebstei’s anomaly

• malformation of the tricuspid valve with low insertion

• results in grossly enlarged R atrium and R ventricle

fetal pericardial effusion

• accumulation of pericardial fluid in utero

• pericardial fluid thickness should be >2 mm to be considered abnormal

sonographic appearance of fetal pericardial effusion:

• seen as anechoic fluid (>2 mm) surrounding the heart

• associated with being an early finding in hydrops

fetal hydrops

an abnormal accumulation of fluid in 2 or more fetal compartments

coarctation of the aorta

• narrowing of the aorta that usually occurs just past the aortic arch near the ductus arteriosus

• can cause back up flow, causing the muscles to work harder and thus thicken

congenital diaphragmatic hernia (CDH)