Fetal Heart (Ch. 36)

cardiac review

• heart lies in mid chest, slightly to left

• ventricles (2)

  • anteriorly to and inferiorly

  • RV is more anterior than LV

• atria (2)

  • posteriorly and adjacent to spine

  • LA is closest to spine

• apex of heart is tilted toward left

cardiac review: RA and RV

RA

• receives deoxygenated blood from IVC and SVC

• sends blood to the RV through the tricuspid valve

RV

• receives deoxygenated blood RA

• sends deoxygenated blood to the lungs via the pulmonary artery (RVOT)

cardiac review: LA and LV

LA

• receives oxygenated blood from the pulmonary veins (4)

• sends blood to the LV through the mitral valve

LV

• receives oxygenated blood from LA

• sends oxygenated blood to the body via the aorta

levocardia

• normal heart position

• apex of heart points to left and bulk of the heart is in the left chest

• denotes both normal position of heart in left chest

dextrocardia

• heart in right chest with apex pointed to right of thorax

• can be associated with normal visceral situs, situs inversus, or situs ambiguous

dextroposition

• heart is located on right side of chest and cardiac apex points medically or left

• usually found when extrinsic factors—space-occupying large diaphragmatic hernia or hypoplasia of right lung are present

levoposition

• heart is displaced further toward the left chest, usually in association with space-occupying lesion

what do you see?

mesocardia

• atypical location of heart, with cardiac apex pointing toward midline of the chest

• heart is located more toward midline

• this may be found with presence of an intracardiac mass or lung abnormality

cardiomyopathy

• disease of myocardial tissue in heart

• causes:

  • exposure to virus (coxsackievirus or mumps) or bacteria leading to infection

  • errors of metabolism

  • endocardial fibroelastosis

myocarditis

• disease of myocardial tissue in heart

• necrosis and destruction of myocardial cells and inflammatory infiltrate

• thinning of myocardial walls, four chambers dilated

pericardial effusion

• abnormal collection of fluid surrounding epicardial layer of heart

• normal amount of pericardial fluid is 2mm or less

• separation of 2mm or more is considered abnormal

• pericardial effusion may be associated with hydrops fetalis

atrial septal defects

• defect in atrial wall that allows for communication b/w two atria

  • oxygen rich blood can flow directly from LA to RA and mix with oxygen poor blood

• 3 types:

  • ostium secundum

  • ostium primum

  • sinus venosus

ostium secundum

• MC type

• occurs in area of foramen ovale

• absence of foramen ovale flap is noted, with fossa ovalis opening larger than normal

• central septum

ostium primum

• cleft of mitral valve causing mitral regurge into left atrial cavity

• defect is located low in atrial septum, near the AV valves

• associated with T21

sinus venosus

• defect is in superior portion of septum

• adjacent to superior vena cava

• less common

which atrial septal defect is this?

ostium primum ASD

which atrial septal defect is this?

ostium secundum ASD

ventricular septal defects (VSD)

• MC congenital heart lesion

  • accounts for 30% of all structural heart defects

• accounts for 30% of all structural heart defects

• abnormal opening in septum between 2 ventricles of the heart

  • isolated VSD is MC cardiac defect

  • appears as an area of discontinuity in interventricular septum

• membranous vs muscular

• good prognosis

  • spontaneous closure can occur in utero and within 1st year of life

  • large defects require surgical treatment

• 4CH view is best to visualize large defects

  • color Doppler can show the movements of flow between the ventricles

atrioventricular septal defects (AVSD)

• previously referred to as endocardial cushion defects of A-V canal defect

• defect in the central part of the heart

  • defect includes: interatrial septum; interventricular septum; mitral valves; tricuspid valves

• results from malformation in the development of endocardial cushion

• good prognosis with surgery worse when associated abnormalities are present

• defect is visualized best in 4CH

• color and spectral Doppler are useful in demonstrating flow directions and degree of regurgitation

AVSDs are associated with…

• chromosomal abnormalities or extra-cardiac anomalies, such as:

  • trisomy 21 (40% of cases)

  • tetralogy of Fallot

  • subaortic stenosis

  • ventricular hypoplasia

  • pulmonary valve stenosis

partial AVSD

• part of ventricular septum hsaa filled in with tissue from AV valves or endocardial cushion

• tricuspid and mitral valves are divided into 2 distinct valves

complete AVSD

• there are defects in all structures formed by the endocardial cushion:

  • atrial septum

  • ventricular septa

  • both AV valves

• common valve between mitral and tricuspid valves

which AVSD is this?

complete AVSD

which AVSD is this?

partial AVSD

Ebstein’s anomaly

• abnormal displacement of tricuspid septal leaflet toward the apex of RV

  • results in regurgitation or leakage from RV back to RA

  • RA is large while RV is small

• best visualized in 4CH view

  • enlargement of RA with inferior displacement of tricuspid valve into RV

  • can be difficult to see if mild

• color/spectral Doppler will reveal regurgitation across the tricuspid valve

hypoplastic left heart syndrome

• small or hypertrophied LV

  • decreased blood flow into or out of LV

  • may have mitral valve dysplasia or atresia

  • minimal communication between LA and LV

• RV ends up supplying both pulmonic and systemic circulations

• ascending AO atresia or stenosis is possible

• extremely poor prognosis (transplantation is usually required)

SONO: hypoplastic left heart syndrome

• small LV

• hypertrophied LV walls

• mitral valve and AO are hypoplastic or atretic

hypoplastic right heart syndrome

• a range of defects secondary to underdevelopment of right side of heart

  • obstruction of right ventricular outflow tract due to pulmonary stenosis

  • small tricuspid valve

  • pulmonary artery stenosis and/or atresia

SONO: hypoplastic right heart syndrome

• small RV

• small or absent PA

• PA stenosis

• VSD may or may not be present

tetralogy of fallot

• MC form of cyanotic heart

• characterized by 4 components:

  • ventricular septal defect

  • right ventricular hypertrophy

  • pulmonary stenosis (RVOT obstruction)

  • overring AO (aorta overrides both ventricles)

• associated with chromosomal abnormalities

4 characteristic of tetralogy of fallot

1. right ventricular outflow obstruction

2. right ventricular hypertrophy

3. AO overrides VSD

4. ventricular septal defect

truncus arteriosus

• only one great artery arises from base of the heart

  • pulmonary, coronary, and systemic arteries arise from common root

• VSD typically present

• can mimic ToF with pulmonary atresia

• too much blood may be sent to lung

  • extra fluid may build up in/around lungs

  • blood vessels to lungs become damaged (pulmonary hypertension)

• surgical intervention is required

• poor prognosis if left untreated

SONO: truncus arteriosus

• 4CH is usually normal

• truncal root overrides ventricular septum

• single great artery

transposition of the great arteries

• when AO arises from RV and PA arises from LV

  • AO from RV sends poorly oxygenated blood to the body

  • PA arising from LV sends well-oxygenated blood back to the lungs

• 3 main arteries leaving the heart are reversed

• leads to shortage of oxygenated blood flowing from heart to rest of body

• associated anomalies:

  • ASD

  • atrioventricular valve anomalies

  • underdevelopment of RV and/or LV

SONO: transposition of the great arteries

• 2 great vessels fro not cross but arise parallel from base of the heart

• 4CH is normal

aortic coarctation

• congenital defect causing narrowing of aortic lumen

• almost 90% are associated with other abnormalities:

  • aortic stenosis; aortic insufficiency; septal defects; TGA; truncus arteriosus; Turner’s syndrome

• narrowing can occur at aortic arch isthmus or left subclavian artery insertion

• good prognosis when isolated; worse if other anomalies present

SONO: aortic coarctation

• difficult to see

• candy can view is best to visualize

echogenic cardiac focus

• bright echogenic dot in ventricle

  • often in LV

• associated with T21 and T13

• isolated finding is typically a normal finding

  • 3-4% of normal fetuses have ECF

rhabdomyoma

• MC fetal intracardiac tumor

  • tend to be multiple and involve septum

• associated with tuberous sclerosis

• fetus becomes symptomatic when tumor is large enough to cause outflow tract obstruction

  • leads to CHF; pericardial effusion; hydrops; death

• prognosis depends on size and location

SONO: rhabdomyoma

• echogenic, solid mass within fetal heart

• fetal echo shows tumor best in 4CH