The Fetal Heart

PAC

(premature atrial contractions)

Cystic Hygroma

1 in 6000 births lymphatic tissues

Diaphragmatic Hernia

1 in every 5000 to 10,000 pregnancies defective diaphragm formation or fusion types: Bochdalek (posterolateral) Morgagni (retrosternal and anteromedial)

Tetralogy of Fallot

4 features VSD overriding Aorta Pulmonary atresia or stenosis Right Ventricular Hypertrophy

normal valves

AV valves: Mitral & Tricuspid Semilunar valves: Aortic & Pulmonic

Advanced Fetal Echo Exams

Additional 2D views RVOT Aortic arch Doppler

Cardiosplenic Syndromes

Associated with asplenia or polysplenia

Pentalogy of Cantrell

Associated with omphalocele & ectopic heart the other three defects are all related to closure defects between the heart and the omphalocele i.e. diaphragmatic hernia Poor prognosis often associated with pleural effusion, other syndromes, monozygotic twins & other fetal anomalies

Fetal Circulation cont

Blood enters the RA Most (~60%) will enter the foramen ovale and then the left atrium (higher pressure) The rest will enter the RV via the tricuspid valve

single ventricle

Both AV valves are present in a single ventricle may be associated with other heart defects

Endocardial Cushion Defects

Caused by a failure of the septa to close or the AV orifice to separate Lead to complete or partial defects associated with T21

Ventricular Hypertrophy

Commonly associated with outlet stenosis or obstruction May indicate cardiomyopathy may be associated with maternal DM poor fetal prognosis

Soft tissue masses of fetal throrox

Cystic Hygroma Nuchal edema

4 Chamber View cont

Determining LV from RV look for moderator band in RV RV slightly larger in utero than the LV TV is a bit inferior to MV

truncus arteriosus

Failure of the truncus arteriosus to separate into the aorta and PA Three types: classified based upon severity Almost always associated with VSD

Pleural Effusion

Fairly common 15% mortality often associated with other pathologies (hydrops)

cardiac development

Fetal heart activity seen by 6-8 weeks MA Fetal heart can be assessed structurally by 14-16 weeks MA incidence of congenital heart disease is 8% of US population The most important period of fetal development for the heart is 31/2 to 61/2 weeks

fetal thorax

Fetal lung more echogenic than liver The fetal heart occupies approximately 1/3 of the fetal chest

Abnormalities of the Fetal Thorax

Hemangiomas Teratomas Hamartomas

Fetal Risk Factors

IUGR, arrhythmias, abnormal amnio (trisomies) & other abnormalities detected by Ultrasound

short Axis View

Image fetus sagitally allows you to sweep through the heart from base to apex Note: 1= MPA 2= DA

Long Axis View

Image fetus transversely documents the ventricles, LVOT, Ao, septum & LA look for the right side of the septum to be continuous with the aortic root to rule out membranous VSD

Ebstein's Anomaly

Inferior displacement of the TV valvular incompetence low RV function paradoxical septal motion TV insufficiency

4 chamber view

Most abnormalities are noted in a 4 chamber view

Hypoplastic Heart Syndrome

Most often affects left side lethal autosomal recessive unknown etiology the unaffected side of the heart enlarges av valve may have regurg due to overload if severe fetus may have hydrops

Diaphragmatic Hernia cont

Most often involves left side associated with major abnormalities 50 - 80% mortality survival rate is significantly higher if there is no associated polyhydramnios

M Mode Anatomy

Normal rate: 120-160 BPM Supraventricular tachycardia: above 200 BPM

grt vssls

Normally the aorta lies to the anterior and right of the PA Pathologically they may lie side by side or the aorta is posterior

Cardiac Echogenic Foci

Not specific to pathology Increased incidence with multiple foci or other findings

Esophogeal Atresia

Note the small stomach and polyhydramnios present

Ectopic Cordis cont

Often associated with other deformities Poor prognosis

Transposition of the Great

Often associated with septal defects Good survival rates with surgical intervention

development

Paired endocardial tubes develop by the end of week 3 and then fuse to form the primitive heart (pg. 1059) cardinal veins return blood from the fetus vitelline veins return blood from the yolk sac umbilical veins return blood from the placenta only one persists Hemopoiesis begins during week 5

The Fetal Heart

Positioned transversely in the fetal chest apex points to fetal left side left atrium closest to spine atria & ventricles should be equal size septa should be uninterrupted

fetal throrax pathologies

Pulmonary Hypoplasia poor prognosis occurs secondary to lung compression skeletal dysplasias oligohydramnios

Cardiac Tumors

Rare seen in any chamber (often the septum) often associated with tuberous sclerosis Other masses include fibromas, myxomas and teratomas

asds Three types

Secundum occurs near foramen ovale Sinus Venosus superior on IAS Primun superior to the AV ring associated with cleft MV leaflet

Fetal Heart Abnormalities

Symmetry RV & LV should appear basically equal in size Rate & Rhythm note any variations

fetal circulation

The fetus receives blood via the umbilical vein may remain patent for some time after birth

Total Anomalous Pulmonary Venous Return

The four pulmonary veins do not return blood to the LA May be associated with VSD and asplenia poor prognosis without surgical intervention

Ectopic Cordis

The primitive heart develops outside the fetus Four types: thoracic abdominal Thoraco-abdominal cervical

Ectopic Cordis cont

Thoraco-abdominal associated with pentalogy of cantrell cervical superior displacement

AVSD (atrioventricular septal defects) Endocardial Cushion Defects

Three Types Complete single AV valve Incomplete membranous septal defect failure of endocardial cushion to fuse Partial Often associated with other cardiac defects

Transposition of the Great cont

Transportation of great arteries shows short-axis view of two great vessels side by side. Aorta is seen to arise from anterior ventricle.

cam

Type III: multiple very small cysts mass appears solid and echogenic via Ultrasound Linked with stillbirth and premature labor or respiratory distress

Coarctation of the Great Vessels

Usually of the aorta narrowing of the vessel walls may be associated with bicuspid valves often associated with other cardiac abnormalities (905)

heart dx

VSD is most common ASD PS 50% of T21 fetus' have CHD

Fetal Development

Week 5: single heart tube forms and begins to beat; lung bud develops Week 6-7: atria & ventricles begin to separate

Fetal Development cont

Week 7: bronchi form Week 10: heart is fully formed Week 26-40: lungs develop respiratory capabilities (mature alveoli form weeks 38-40)

Adenomatoid Malformation (CAM)

accounts for 24% of lung malformations unilateral development of multiple cysts of varying sizes Type I: a single large cyst Type II: multiple mid sized uniform sized cysts both type I & II appear cystic via Ultrasound

4 Chamber View

apex lies perpendicular to fetal spine will note the patent foramen ovale (opens from RA into LA)

Transposition of the Great Levotransposition (l-TGA)

arteries arise from the functionally correct ventricle but the ventricles are reversed Aorta is to left of PA

Polysplenia

associated with bilateral left sidedness

Asplenia

associated with bilateral right sidedness high associated with asplenia and CHD

Tetralogy of Fallot cont

associated with other abnormalities prognosis is good if not associated with pulmonary atresia

Blood enters the LA from the foramen ovale, fetal lungs & IVC

blood passes through the mitral valve into the LV passes through the aortic valve and primarily feeds fetal cranial structures off of aortic arch

The ductus arteriosus

closes and becomes the ligamentum ateriosum after birth

Nuchal edema

creates a halo appearance due to fetal immune hydrops, demise or some skeletal dysplasias soft sign of T21 Done before 13 weeks GA Nuchal translucency < 2.5 mm

fetal circulation cont

enters liver to anastamosis with the left portal vein Most blood will enter the IVC via the hepatic veins 10 - 50 % of blood will bypass the liver and enter the ductus venosus and either entering the IVC directly or via the hepatic veins

To determine left vs. right heart look for:

foramen ovale flap opens into LA moderator band in RV (muscles near apex)

Fetal Circulation cont

from the RV blood passes through the pulmonic valve to enter the main pulmonary artery Most (90%) enters the descending aorta via the ductus arteriosus bypasses nonfunctioning fetal lungs

Maternal Risk Factors

heart disease, drug ingestion, poly or oligohydramnios, DM (increased risk of cardiomyopathy), rH sensitization, collagen vascular dx & preeclampsia

Pleural Effusion cont Non immune hydrops

high risk of mortality causes include cardiac abnormalities, infections (TORCH), chromosomal abnormalities, masses which cause venous obstruction, and renal abnormalities most often causes are extrathoracic

Pulmonary sequestration

identified in fetus, in addition to large pulmonary embolus that surrounded mass of lung tissue. Masses composed of nonfunctioning primitive pulmonary parenchymal tissue that have no connection to the tracheobronchial tree

Transposition of the Great VesselsDextrotransposition (d-TGA)

is most common Aorta arises from RV PA arises from LV

ventricular septal defects

most common form of CHD (30%) most often occur near the AV valves membranous defects

Pleural Effusion cont rH sensitization (immune hydrops)

mother is sensitized by a previous pregnancy to blood factor incompatibility an immune reaction between maternal and fetal blood (rH) factor occur treatment by Rhogram reduces incidence from 98% to 90% of histoincompatible pregnancies

Semilunar Valves

regulate blood from outflow tracts aortic valve (3 leaflets) pulmonary valve (3 leaflets)

most common tumor

rhabdomyoma and rhabdosarcomas

AV Valves

separate atria and ventricles Tricuspid (3 leaflets) Mitral (2 leaflets)

5 Chamber View

slight anterior angulation introduces LVOT into image Useful when obtaining doppler signals from the AoV, PoV or AV valves

Familial Risk Factors

syndromes, CHD in a sibling

Ectopic Cordis cont

thoracic develops outside the thorax through a sternal defect abdominal develops in the abdomen through a diaphragmatic defect

Doppler

too look for regurgitation at valves assess septal defects determine pressure gradients

Fetal heart is best evaluated between weeks 20 & 34

very dependant upon fetal positioning Use M Mode measurements heart rate