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 ┬ęCopyright
 Published: 29/11/2011

Cardiology

Tetralogy of Fallot Transposition of the Great Arteries Pulmonary Atresia Patent Ductus Arteriosus
Dextrocardia Other Abnormalities of Cardiac Position Hypoplastic Left Heart Syndrome Ebstein's Anomaly
Hypertrophic Cardiomyopathy Pericardial Effusion Left SVC Non-cardiac causes of cardiac failure
 

See also the S.T.A.B.L.E. Cardiac Module Program (via the intranet only)

Tetralogy of Fallot

Tetralogy.jpg (21002 bytes)

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.

 

Transposition of the Great Arteries

TGA.jpg (35323 bytes)

Transposition of the Great Arteries (TGA) is the most common cyanotic congenital cardiac condition to present in the immediate neonatal period, particularly if no ventricular septal defect (VSD) is present and there is poor mixing of blood at the atrial level.  Infants can present in shock and severely acidotic. Clinically, the babies will appear cyanosed.  No murmur is present, unless there is a VSD or some other structural cardiac lesion.

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.

 

Pulmonary Atresia

PulmonaryAtresiaIVS.jpg (44089 bytes)

Pulmonary atresia is a condition where the pulmonary valve does not form properly and there is no flow from the right ventricle into the pulmonary circulation.  This is a lesion which is duct dependent for adequate pulmonary blood flow.  If the ventricular septum is intact, then there can be early severe cyanosis on the first day.  If a VSD is present, the presentation may be later.  The right ventricle is often hypoplastic.  The degree of atrial communication, allowing systemic blood return to the right atrium and thence the left atrium, is important.  The chest radiograph will show oligaemic lung fields.  The cardiac silhouette may be normal size, or enlarged (in the case shown to the left, this was from right atrial enlargement due to poor communication between right and left atria via a restricted foramen ovale). Fistulae from the right ventricle to the coronary circulation may be present, particularly if the right ventricle and tricuspid valve are small.

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.

 

Patent Ductus Arteriosus

CXR - PDA.jpg (224857 bytes)

Patent ductus arteriosus (PDA) is common in the very preterm infant with significant lung disease.  Radiological signs are non-specific.

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

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Dextrocardia with situs inversus

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Dextrocardia with situs solitus

Dextrocardia is a description term indicating that the heart is in the right hemithorax. Dextrocardia may be because a normally left-sided heart (levocardia) is displaced to the right side (either because of pressure from a mass in the left hemithorax, or collapse of the right lung drawing the heart to that side) or because the heart is "flipped" around and is anatomically inverted.

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.

 

Other Position Abnormalities

SitusAmbiguous.jpg (30952 bytes)

As well as the general position in the chest that the heart occupies, it is also important to define where the individual chambers of the heart are placed.  This is most easily done using echocardiography to define atrial and ventricular positions.  Defining the bronchial anatomy on plain radiographs may also be useful.

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.

 

Hypoplastic Left Heart Syndrome with Pulmonary Congestion

CXR - HLHS - congested.jpg (255887 bytes)

The radiograph to the left shows pulmonary venous congestion in an infant with hypoplastic left heart syndrome (HLHS).

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.

 

 

Ebstein's Anomaly

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Ebstein TR.JPG (112790 bytes)

This is a right heart anomaly with downward displacement of the tricuspid valve leaflets into the right ventricle.  There is generally an ASD through which there is right-to-left flow.

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.

 

Hypertrophic Cardiomyopathy

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This is usually reactive and resolves once the underlying cause resolves. It is often seen in infants of diabetic mothers, and can be induced by hypertension and by postnatal corticosteroids.

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.

Pericardial Effusion

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CXR - Pericardial effusion - postdrain.jpg (134504 bytes)

Pericardial effusions may be seen in utero in association with fetal hydrops. In this situation, they generally reflect poor cardiac output, and are usually seen with other signs of hydrops (oedema, pleural effusions, ascites, polyhydramnios).

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.

Left SVC

 

Although a left SVC occurs in approximately 0.5% of the normal population, it occurs in up to 4% of infants with congenital cardiac disease.  It usually drains into the coronary sinus.

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.

Non-cardiac Causes of Cardiac Failure

It is important to consider non-cardiac causes of cardiac failure in infants - not all large hearts have a primary aetiology that is due to structural cardiac disease.

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

 

Last updated November 29, 2011