Tetralogy of Fallot is a structural cardiac lesion consisting of

• a conal ventricular septal defect
• right ventricular (subpulmonary) outflow tract obstruction
• an aorta which overrides the VSD, and
• right ventricular hypertrophy

Tetralogy usually presents with cyanosis, the degree of which is dependent on the degree of RVOT obstruction and therefore right-to-left shunting.  In severe cases of pulmonary stenosis or pulmonary atresia, pulmonary blood flow may be duct-dependent.

Radiologically, the heart size is usually normal.  There is elevation of the cardiac apex, secondary to right-ventricular hypertrophy. The cardiac silhouette is often described as "boot-shaped".  The lung fields are usually clear and in cases of severe outflow tract obstruction may appear oligaemic.  There may be a concavity of the left border of the heart usually occupied by the pulmonary artery.

The radiological appearances can vary depending on other associated cardiac lesions.  For example, if collateral vessels are present between the aorta and pulmonary circulations, there may be pulmonary plethora.

Radiologically, the lungs appear to have increased blood flow and increased pulmonary vascular markings.  The mediastinum is narrow, as the great arteries are running parallel.  Diagnosis is made by echocardiography - important features to note are the size of the ductus arteriosus, whether there is a VSD, and how much atrial mixing there is.

Infants with a large VSD or large atrial communication may present later, within the first 2 weeks, with cyanosis.  Cardiac failure may be present in the presence of a large VSD.

In the short-term, a prostaglandin infusion should be commenced to ensure ductal patency. A balloon artial septostomy is usually performed within the first day or two of life to assist with mixing at an atrial level. An arterial switch procedure is usually performed within the first week.

In the short-term, a prostaglandin infusion should be commenced to ensure ductal patency. A balloon atrial septostomy may need to be performed within the first day or two of life to assist with return of systemic venous blood into the systemic circulation. Definite treatment is dependent on the lesions present and whether a reasonable RV outflow can be created.

However, if the PDA is large with a significant left-to-right shunt, the lung fields will become generally hazy and the heart enlarges.  This may or may not be in association with evolving CLD.

The top image to the left shows a baby with a large duct.  The heart is generous and the lung fields are non-specifically hazy.  The baby also has significant neonatal Chronic Lung Disease.

The second image shows cardiomegaly and some pulmonary plethora in a 4-week old baby with a large duct which had not closed with two courses of treatment with Indomethacin.

For echocardiography images of the ductus, click here.

Dextrocardia with situs solitus

Dextrocardia with situs inversus (reversed abdominal contents) is essentially a mirror image of a heart, with a mirror image of the abdominal contents. In this situation, the cardiac anatomy and connections are usually (but not always) normal.

In dextrocardia with situs solitus (normally-oriented abdominal contents), congenital cardiac disease is more likely. The lesions are frequently complex and often require surgical correction.

Clincally, the heart sounds may be louder on the right than the left (and a diagnosis of left-sided tension pneumothorax may erroneously be made prior to a radiograph being available). There may be symptoms and signs of congenital heart disease if associated anomalies are present. "Asymptomatic" dextrocardia may present with features of Kartagener's syndrome (Primary Ciliary Dyskinesia, PCD, leading to bronchiectasis and nasal symptoms).  For infants with situs inversus, referral to a Respiratory Service for assessment of PCD is suggested.

Dextrocardia may also be an incidental finding on a chest radiograph done for other reasons. In this case, it is important to ensure that the radiograph has been correctly labelled.

There are a number of potential abnormalities in position of the atria, ventricles, and abdominal contents.  It is also useful to define, in cases of ambiguous abdominal contents, whether there is asplenia or polysplenia.  Complex cardiac anomalies are common in these situations.  With asplenia, there is a risk of overwhelming sepsis.

The image to the left shows an infant with a relatively central cardiac silhouette.  The NG tube is seen draining to the right side of the abdomen.  The liver appears to be centrally placed.  The echocardiogram demonstrated a complex anomaly with pulmonary atresia, a common atrium, a large VSD, and transposition of the great arteries.

Fetal echocardiography had identified cardiac anomalies consistent with this sequence, with aortic atresia and mitral stenosis.  Of concern, the left atrium was large and there was no clear atrial shunt to allow pulmonary venous return to cross into the right atrium.

HLHS may be diagnosed antenatally on routine anatomy scan, primarily because the ventricles are identified by their different sizes on the 4-chamber view.

Infants with HLHS who have a reasonable atrial communication may have a radiograph which is not markedly abnormal, and the baby may be reasonably well.  However, it is also one cardiac lesion that can present at or soon after birth with an infant in poor condition if there is poor atrial mixing through a restrictive atrial septum.  Because of the pulmonary congestion, the baby can have significant respiratory distress and remain severely cyanosed.

The tricuspid valve is regurgitant, part of the right ventricle is in free communication with the right atrium, the right atrium is enlarged (sometimes spectacularly), and the right ventricular cavity can be small.

The radiograph to the left demonstrate marked cardiac enlargement (a "carpet" heart).

The echocardiography images to the left demonstrate a markedly enlarged right atrium and a dysplastic tricuspid valve that does not fully close in systole (the colour Doppler image shows marked tricuspid regurgitation).  The right ventricle in this example is a reasonable size but was functioning poorly. The tricuspid valve was only mildly displaced into the right ventricle.

There is a spectrum of severity.  Presentation in the newborn period with cyanosis usually reflects a severe anomaly and the prognosis is poor.  There may be associated pulmonary hypoplasia if atrial enlargement restricts in-utero pulmonary development.  In older children, a mild anomaly may be found as an incidental finding.

There may occasionally be obstruction of the outflow tract. Medical treatment in severe cases include β-blockers.

These radiographs are from a macrosomic infant. The mother was not confirmed to have gestational diabetes. The baby had respiratory distress and an initial radiograph demonstrates marked cardiac enlargement and some plethora of the lung fields. An echocardiogram showed normal connections and anatomy but demonstrated marked ventricular hypertrophy - particularly of the septum - without obstruction of the left ventricular outflow tract. The second radiograph, taken at two weeks of age, shows a normal cardiac size with clear lung fields.

Postnatally, they may be due to a number of causes also.  An important cause to consider is possible cardiac perforation from a UVC or longline.  In this situation, aspiration of the pericardial fluid can lead to instant and dramatic improvement in the clinical condition.

The images to the left show an infant with a large pericardial effusion. The heart is large and the lung fields are diffusely hazy.

The second image shown follows insertion of a pericardial catheter.  The cardiac size has decreased and the lung fields look clearer.  Note that there is now significant subcutaneous oedema.  There is also some right upper lobe collapse.

The image to the left demonstrates a persistent left SVC, nicely identified with the insertion of a longline that has found its way down the aberrant vessel.  The baby had normal cardiac anatomy.

The image to the left shows the radiograph of an infant who presented on the third day of life with signs of congestive cardiac failure.  The heart was structurally normal but grossly enlarged and demonstrated poor function.  The infant was in cardiac failure as a result of high output through a vein of Galen malformation.

Non-cardiac causes of congestive cardiac failure include:

• hyperthyroidism
• AV malformations
• multiple haemangiomas
• hypoglycaemia
• hypocalcaemia
• asphyxia
• sepsis
• severe anaemia
• polycythaemia
• renal failure
• severe systemic hypertension
• adrenal insufficiency
• metabolic diseases (e.g. Pompe disease)
• renal failure

Non-structural cardiac causes of congestive heart failure include:

• myocarditis
• cardiac arrhythmias (e.g.  sustained SVT, complete heart block)
• anomalous left coronary artery