Cardiomegaly in the newborn may be associated with many types of congenital heart disease or systematic illness. When a massive "wall-to-wall" cardiothymic slhouette is found, the possible causes are fewer. In this article, the authors review some such causes and their radiologic signs.
Although a definitive diagnosis of most types of congenital
heart disease is made with echocardiography, chest radiographs
often are the initial imaging study used. Accurate interpretation
of these radiographs facilitates appropriate work-up and
Cardiomegaly in the newborn may be associated with many types of
congenital heart disease or systemic illness. However, when a
massive "wall-to-wall" cardiothymic silhouette is found on a chest
radiograph, the possible causes are fewer. Most cases of
wall-to-wall heart are related to massive right atrial enlargement,
found in such disorders as Ebstein's anomaly of the tricuspid valve
or pulmonary atresia with intact ventricular septum (PA-IVS).1-3
Other causes of a massive cardiac silhouette include pericardial
effusions, atypical large arteriovenous shunts, hypertrophic
cardiomyopathy in infants of diabetic mothers, and cardiac or
mediastinal masses mimicking massive cardiomegaly.
There may be some degree of overlap in the clinical presentation
of this group of neonates. Newborns with noncardiac causes of
massive cardiac silhouette can present with symptoms similar to
those with congenital heart disease, which are tachypnea and
wheezing. Cyanosis also may be present, related to cardiac or
venous compromise secondary to compression.
Massive right atrial enlargement PA-IVS and Ebstein's anomaly
can result in massive right atrial enlargement. This produces the
largest cardiac silhouettes seen in neonates.1-3 When massive
cardiomegaly is associated with decreased pulmonary flow, Ebstein's
anomaly or PA-IVS is the most likely diagnosis. The degree of
cardiomegaly in PA-IVS is related to the competency of the
When tricuspid regurgitation is present, blood flows "back and
forth" from the right ventricle to the right atrium, and the right
atrium and right ventricle can become massively enlarged (figure
1).1 In Ebstein's anomaly, there is redundancy and downward
displacement of the leaflets of the tricuspid valve into the right
ventricle, with adherence of these leaflets to the right
ventricular wall distal to the atrioventricular annulus. This
results in a tripartite right heart, divided into the right atrium,
an atrialized right ventricle
(portion of the right ventricle located between the
atrioventricular annulus and the displaced tricuspid valve), and
the right ventricle.4 A combination of functional and structural
obstruction leads to massive enlargement of the anatomic right
atrium and atrialized right ventricle (figure 2).3,4
Hypertrophic cardiomyopathy in infants of diabetic mothers
In infants of diabetic mothers, an increase in myocardial mass
may result in hypertrophic cardiomyopathy and can be a cause of
massive cardiomegaly (figure 3).5,6 Congestive heart failure also
can contribute to the degree of cardiomegaly.5 In these neonates,
there is enlargement of the myocardial cell resulting in increased
myocardial mass. This myocardial hypertrophy can result in
diminished left ventricular function (nonobstructive
cardiomyopathy), as well as left ventricular outflow tract
obstruction (obstructive cardiomyopathy).5
Another cause of cardiomyopathy in neonates is hypoxic-ischemic
cardiomyopathy, or the so-called "stunned myocardium." Hypoxia
related to birth asphyxia can result in temporary myocardial
dysfunction and resultant cardiac enlargement.
Large arteriovenous shunts
When very large amounts of arteriovenous shunting occurs,
resultant cardiomegaly can be massive. These atypically large
shunts can be peripheral, such as arteriovenous malformations of
the liver, brain, or skin (figure 4), or intracardiac, such as a
coronary artery-right heart fistula (figure 5).7 In these cases,
pulmonary vascularity may be normal on radiographs because the
increased pulmonary vascular resistance present in newborns impedes
any increase in pulmonary arterial flow.
Large pericardial effusions
Pericardial effusion in the absence of hydrops fetalis or sepsis
is rare in neonates.8 In a previous review of 32 cases of neonatal
pericardial effusion, cardiac tumor was a common cause (38%), with
teratoma and cavernous hemangioma/hemangioma being the most common
types.8 Other common causes included thyroid dysfunction (21%),
infection (12%), and diaphragmatic hernia into the pericardial sac
(16%).8 When large enough, pericardial effusions can cause massive
enlargement of the cardiac silhouette (figure 6).
Masses mimicking cardiac chamber enlargement
Chest masses can sometimes produce the radiographic
"wall-to-wall" appearance of the heart in newborns, mimicking
diseases such as Ebstein's anomaly. We have seen this occur with
cardiac masses such as rhabdomyomas (figure 7), mediastinal masses
such as teratomas (figure 8), and congenital diaphragmatic hernias
on early films, before gas enters the bowel (figure 9). Children
with tuberous sclerosis are predisposed to developing
Many technical factors can influence the apparent cardiac size
seen on frontal radiographs. In neonatal intensive care units,
radiographs often are obtained using the portable
anterior-posterior technique in frontal projection only.
Anterior-posterior projection, lordotic or rotated positioning, and
large focus-film distance all may cause the magnification of
apparent cardiac size.9 Under these circumstances, a normal heart
can appear to be enlarged (figure 10), especially if the film is
obtained during expiration. Additionally, a normal thymus can
appear large relative to the newborn mediastinum and mimic
cardiomegaly on frontal radiographs. In cases where cardiac
enlargement is in question on frontal radiographs, lateral
radiographs are helpful in determining whether cardiac enlargement
is true or artifactual. AR
1. Kanjuh VI, Stevenson JE, Amplatz K, et al: Congenitally
unguarded tricuspid orifice with coexistent pulmonary atresia.
Circulation 30:911-915, 1964.
2. Anderson KR, Lie JT: Pathologic anatomy of Ebstein's anomaly
of the heart revisited. Am J Cardiol 41:739-745, 1978.
3. Strife JL, Bisset GS III: Cardiovascular system. In: Kirks DR
(ed), Practical Pediatric Imaging, pp 417-513. Boston, Little,
Brown and Company, 1991.
4. Bialostozky D, Horwitz S, Espino-Vela J: Ebstein's
malformation of the tricuspid valve: A review of 65 cases. Am J
Cardiol 29:826-836, 1972.
5. Dunn V, Nixon GW, Jaffe RB, Condon VR: Infants of diabetic
mothers: Radiographic manifestations. AJR 137:123-128, 1981.
6. Way GL, Wolfe RR, Eshaghpour E, et al: The natural history of
hypertrophic cardiomyopathy in infants of diabetic mothers. J
Pediatrics 95:1020-1025, 1979.
7. Jaffe RB, Glancy DL, Epstein SE, et al: Coronary
arterial-right heart fistulae: Long-term observations in seven
patients. Circulation 47:133-143, 1973.
8. Cartagena AM, Levin TL, Issenberg H, Goldman HS: Pericardial
effusion and cardiac hemangioma in the neonate. Pediatr Radiol
9. Amplatz K, Moller JH: Radiology of Congenital Heart Disease,
pp 55-113. St. Louis, Mosby-Year Book, Inc., 1993.