The document discusses three main groups of cells that contribute to heart morphogenesis: primary and secondary heart fields located in the lateral plate mesoderm and cardiac neural crest. It also discusses techniques for assessing the pediatric heart, including echocardiography, chest radiography, CT angiography, MRI, and nuclear cardiology. Key points are made about each imaging modality and their clinical applications for evaluating pediatric cardiac anatomy and function.

2. Three main groups of cells contribute to the
morphogenesis of the heart
• Primary heart fields (located in the splanchnic layer of
lateral plate mesoderm bilaterally)
• Secondary heart fields (located in the pharyngeal
mesenchyme), and
• Cardiac neural crest (a subdivision of the cranial portion of
the neural crest)

3. Three main groups of cells contribute to the
morphogenesis of the heart

4. Cardiac Development
• Only the penetrating bundle of His normally electrically connects (via
muscle to muscle) the atria and the ventricles.
• The atrioventricular canal of the heart is divided into right and left sides by
endocardial cushions that develop at the atrioventricular junction and
ultimately form the septum of the atrioventricular canal and the
atrioventricular valves.
• The right atrioventricular canal and right ventricle expand to the right, and
the atria are septated from one another.
• Septum primum, the primary atrial septum, is led by the spina vestibuli
(vestibular spine) and ultimately fuses with the endocardial cushions to
close the first interatrial communication, or ostium primum.

5. Pediatric Echocardiography
• Echocardiography is the primary imaging modality used to assess the
heart and the vasculature proximal to the heart in pediatrics.
• Vascular ultrasound typically is used to assess the remainder of the
vasculature
• Echocardiography is sufficiently robust to be used as the sole imaging
modality in assessing cardiac anatomy before surgical repair in most
pediatric patients with congenital heart disease.

6. Techniques:
• Transthoracic echocardiography is an ultrasound technique that is
optimized for imaging the moving heart
• Doppler echocardiography uses color and spectral Doppler in the
same manner as in vascular ultrasound imaging. In a typical
echocardiographic examination, all cardiac valves are assessed by
spectral Doppler, as are the aortic arch at the isthmus and any
identified septal defects.
• Transesophageal echocardiography in the pediatric population is used
primarily in the operating room during surgery for congenital heart
disease and in the interventional cardiac catheterization laboratory.

7. Key points: Pediatric Echo
• 1. Most pediatric patients with congenital heart disease are taken to
the operating room on the basis of an echocardiographic diagnosis
alone
• 2. Standard imaging planes for echocardiography relate to the axes of
the heart, not to the axes of the body
• 3. The heart is best understood by considering its anatomy
segmentally

8. Chest Radiography in Pediatric Cardiovascular Disease
• The major chest radiographic findings in patients with cardiac disease
are cardiomegaly, pulmonary vascular changes (predominantly over
circulation or under circulation), and signs of pulmonary venous
hypertension and edema.

9. • HEART SIZE. The lateral view provides a more reliable indication of
true heart size by permitting an assessment of the anteroposterior
dimension without interference from the thymus.
• PULMONARY VASCULATURE. The size of the pulmonary vessels is
noticeably larger only when the amount of flow doubles (thus when
the pulmonary systemic ratio is 2:1)
• Pulmonary Venous Hypertension and Pulmonary Edema Early pulmonary
venous hypertension often manifests as hyperinflation in infants younger
than 2 years. As interstitial fluid accumulates, the perihilar bronchi and
vessels become poorly defined. Septal (i.e., Kerley) lines are uncommon in
children. Eventually, frank alveolar pulmonary edema is seen
Chest Radiography in Pediatric Cardiovascular Disease

10. • SITUS The chest film assessment is incomplete unless abnormalities
of abdominal and thoracic situs (the anatomic location of organs that
are asymmetrically positioned in the body) are sought and the cardiac
position relative to visceral situs is determined. Dextrocardia in situs
solitus is strongly associated with complex cardiac abnormalities.
Chest Radiography in Pediatric Cardiovascular Disease

11. Key Points: Chest Radiography
• Changes in pulmonary vascular resistance influence the
manifestations of cardiovascular disease in the newborn.
• Hyperinflation is a sign of congestive heart failure in infants
• Chest films may appear normal even in children with serious heart
disease.

12. Pediatric Cardiothoracic CT Angiography
• Computed tomography (CT) provides the best global assessment of
the lungs and airways, as well as other regional structures, in both
congenital9 and acquired vascular disorders.
• MDCT or dual-source MDCT, complete examination of the entire
chest of an infant can be completed in less than 1 second.
• A reduced examination time means that CT is better tolerated by infants,
children, and patients in the intensive care unit who may have a limited ability
to hold still or require the examination to be performed quickly for other
reasons

13. • Technique is critical for optimizing pediatric cardiovascular CT angiography
in children.
• Pediatric CT angiography is less protocol driven than with adults.
• If performed properly, non gated and even gated CT angiography in
children can result in dose estimates at or below 1.0 mSv in certain
circumstances.
• Familiarity with clinical questions and anatomy with congenital disorders
will afford the greatest potential for safe and highquality pediatric
examinations.
• Lower peak kilovoltage (e.g., 80 and 100kVp) can be used in CT
angiography compared with other body imaging because of high contrast
vascular enhancement
Pediatric Cardiothoracic CT Angiography

14. • Spin echo and gradient echo sequences are used for cardiac
evaluation. Spin echo, or “black blood,” imaging gives excellent
contrast resolution between the endocardium or vessel wall and the
blood-filled lumen.
• MRI is the gold standard for cardiac function assessment and is
markedly superior to echocardiography in assessing right ventricular
function.
• Contrast-enhanced magnetic resonance angiography (CEMRA) is
performed after injection of a gadolinium chelate bolus. The
technique relies on T1 shortening of blood and requires rapid imaging
Pediatric Cardiothoracic MRI

15. Pediatric Nuclear Cardiology
• Nuclear cardiovascular examinations complement anatomic imaging
modalities by providing noninvasive methods to assess myocardial
perfusion, myocardial viability, myocardial function (including ejection
fraction and wall motion), cardiac shunts, and regional pulmonary blood
flow in children with congenital and acquired anomalies of the heart and
great vessels
• Myocardial perfusion images are obtained by using single photon emission
tomography (SPECT) after administration of an intravenous tracer during a
time of peak stress and while the patient is at rest
• For children who are too young to cooperate with exercise testing (usually,
children younger than 4 or 5 years), pharmacologic stress testing with use
of vasodilators such as dipyridamole and adenosine or inotropic drugs such
as dobutamine can be performed safely.

16. Abnormal Pulmonary and Systemic Venous
Connections
• Partial Anomalous Pulmonary Venous Connection and Scimitar
Syndrome
• Total Anomalous Pulmonary Venous Connection
• Cor Triatriatum and Other Anomalies of the Pulmonary Veins