Chamber Asymmetry
Michael D. Puchalski, MD
DIFFERENTIAL DIAGNOSIS
Common
Hypoplastic Left Heart Syndrome (HLHS)
Tricuspid Atresia (TA)
Pulmonary Valve Atresia with Intact Ventricular Septum
Tricuspid Dysplasia
Ebstein Anomaly
Less Common
Atrioventricular Septal Defect (AVSD), Unbalanced
Coarctation of the Aorta
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Are there one or two ventricles?
If only one, is it morphologically the right or left ventricle?
If two ventricles, do they both reach the apex of the heart?
Are there one or two atrioventricular (AV) valves?
If only one AV valve, is it the anterior (tricuspid) or posterior (mitral) valve?
Are the AV valves normal in size?
Are the valves located in the same plane or off-set?
Normally tricuspid insertion is more apical than mitral
Is there AV valve regurgitation?
Are there one or two great arteries?
Are they normal in size?
Does blood flow into both from the heart?
Is perfusion from the ductus?
Helpful Clues for Common Diagnoses
Hypoplastic Left Heart Syndrome (HLHS)
Abnormal four chamber view with small, non-apex-forming left ventricle (LV)
May see brightly echogenic LV endocardium with endocardial fibroelastosis
LV function is poor
Inter-atrial septum bowed left to right as flow across foramen ovale is reversed
Little or no antegrade flow from LV so LA blood refluxes into RA
Aortic valve often atretic and/or very small
Ascending aorta very small
Transverse arch very small
Right ventricle is large
RV wraps around apex of LV
Function is typically very good, even hyperdynamic
Tricuspid Atresia (TA)
Abnormal four chamber view
Small, non-apex-forming right ventricle
Left ventricle is normal to large in size with good function
Tricuspid valve appears “plate-like” with no movement
Ventricular septal defect (VSD) usually present to provide blood flow to great artery arising from RV
Size of great artery arising from RV depends on size of VSD
Larger VSD → bigger vessel
Vessel may be pulmonary artery or aorta
Pulmonary Valve Atresia with Intact Ventricular Septum
Four chamber view is abnormal
RV very hypertrophied and small
RV pressure is usually greater than systemic
Tricuspid valve often hypoplastic
Look for abnormal coronary flow over RV
Indicates presence of coronary sinusoids
Low velocity flow in small vessels
Reversed flow in the ductus arteriosus
Pulmonary artery fills retrograde from aortic arch, not antegrade from right ventricle
Ductus arteriosus is more vertically oriented than usual
Tricuspid Dysplasia
Valve leaflets are in normal position
Leaflets are thick, nodular, or irregular
Severe tricuspid regurgitation (TR) → right atrial enlargement
Often associated with pulmonary stenosis/atresia
LV normal in size with good function
Ebstein Anomaly
Apical displacement of septal and mural tricuspid valve leaflets with attachments to ventricular septum
Anterior leaflet is often “sail-like”
“Atrialization” of the right ventricle
Significant right atrial enlargement
Functional RV is small
Variable degrees of TR
Pulmonary artery is often small
Severe TR → lack of antegrade flow to RV
Helpful Clues for Less Common Diagnoses
Atrioventricular Septal Defect (AVSD), Unbalanced
Missing “crux” of heart in four chamber view
Inlet ventricular septal defect
Primum atrial septal defect
Single AV valve is committed more to one ventricle than the other
Valve located in the same plane in a four chamber view is a tip-off
Normally tricuspid and mitral valves offset on interventricular septum
Ventricle lacking commitment will be hypoplastic
Additional cardiac malformations are common
Look for features of heterotaxy syndromes
Situs abnormalities (e.g., dextrocardia, right-sided stomach)
Midline liver with central portal vein bifurcation
Anomalous venous drainage especially azygous continuation of inferior vena cava
Look for signs of trisomy 21
Thick nuchal fold, absent nasal bone
Duodenal atresia, echogenic bowel
Short humerus, femur
Pyelectasis
Sandal gap toes, clinodactyly
Coarctation of the Aorta
RV mildly enlarged compared to LV
Transverse arch hypoplasia is best clue
VSD with posterior deviation of the infundibular septum raises suspicion
Difficult prenatal diagnosis
Other Essential Information
HLHS, TA, and unbalanced AVSD
All considered single ventricles and require 3 stage surgical palliation
Outcomes for HLHS have improved in the short-term but remain poor for long-term
Outcomes for TA are better than HLHS with survivors into their 40s and 50s
Outcomes for an unbalanced AVSD depend on which ventricle is dominant and associated anomalies
Pulmonary atresia with intact ventricular septum can have a very poor prognosis
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