Rush Center for Congenital
and Structural Heart Disease

Normal CXR
 

Antero-posterior view

The cardiac silhouette occupies 50-55% 0f the chest width. Cardiomegaly is when the cardiothoracic (CT) ratio is more than 55%.
The superior vena cava, ascending aorta and the right atrial appendage form the remainder of the upper portion of the right border of the cardiac silhouette&127;. The lower half of the right border of the cardiac silhouette is formed by the right atrium, the right ventricle does not contribute to the right border of the heart.
The left border of the cardiac silhouette is formed by the aortic arch (aortic Knob), pulmonary trunk, left atrial appendage. The lower half of the left cardiac border is formed by the left ventricle.

 

Lateral view

The cardiac silhouette in this view is oval in shape and occupy the anterior half of the thoracic cage.
The ascending aorta and right ventricle form the anterior border, while the left atrium and left ventricle form the posterior border.

 

 

 

 

 

Normal AP CXR

 

 

In this illustration, the outlines of right heart structures are superimposed over an AP CXR.

 

In this illustration, the outlines of right heart structures are superimposed over an lateral CXR.

 

In this illustration, the outlines of left heart structures are superimposed over an lateral CXR.

 

In this illustration, the outlines of left heart structures are superimposed over an lateral CXR.

 

Atrial Septal Defect (ASD)

AP view

The pressure in the left atrium is higher than the right atrium. therefore, a defect in the atrial septum will result in left to right shunting of blood. The increased blood volume flowing through the right heart and pulmonary vasculature will cause prominent pulmonary vascular markings on chest X-Ray, and in moderate to severe cases there will also be cardiomegaly due to right atrial enlargement causing prominence of the right heart border.

 

 

Lateral View

Prominent pulmonary vasculature is noted, particularly in the hilar region. In severe cases the right ventricle is dilated, this will be manifested by fullness of the anterior border of the heart in the lateral views resulting in obliteration of lung tissue normally noted in between the heart and sternum.

 

 

 

 

Ventricular Septal Defect (VSD)

AP view

VSD causes left to right shunting of blood at the ventricular level leading to excessive pulmonary blood flow.  The right ventricle may or may not dilate.  The increase in pulmonary blood flow will manifest as engorged pulmonary vasculature.  The increase in return of blood to the left atrium and ventricle will cause left atrial and ventricular dilation.

 

 

Lateral view

The lateral view shows dilated left atrium which causes the barium filled esophagus in this barium swallow study to deviate posteriorly, away from the dilated left atrium.

 

 

Patent Ductus Arteriosus (PDA)

PDA causes left to right shunting at the arterial level causing engorged pulmonary vasculature.  The main pulmonary artery gets dilated and the left atrium is dilated due to increase pulmonary venous blood return.

 

 

Atrio-Ventricular Canal Defect (AVC Defect)

Left to right shunting across typically large atrial and ventricular septal defects will cause dilation of all cardiac chambers causing significant cardiomegaly on CXR.  Excessive pulmonary blood flow causes engorgement of pulmonary vasculature.  AV valve regurgitation is not unusual in this defect, this may further aggravate cardiomegaly.

 

Pulmonary Stenosis (PS)

Narrowing of the pulmonary valve orifice causes the blood flow across the narrow valve to be jet like which may cause the main pulmonary artery to dilate, this manifests as prominence of the pulmonary artery segment in the mid-left border of the cardiac silhouette.  Severe and prolonged pulmonary stenosis, or in critical pulmonary stenosis in the newborn, RV failure and consequently dilation and cardiomegaly by CXR will manifest.

 

 

Aortic Stenosis (AS)

Narrowing of the aortic valve orifice causes the blood flow across the narrow valve to be jet like which may cause the ascending aorta to dilate, this manifests as prominence of the ascending aorta segment in the mid-right border of the cardiac silhouette.  Severe and prolonged aortic stenosis, or in critical aortic stenosis in the newborn, LV failure and consequently dilation and cardiomegaly by CXR will manifest.  
 

Coarctation of the Aorta (CoA)

Typically coarctation of the aorta is not detectable by CXR.  Prolonged and severe coarctation of the aorta may lead to LV hypertrophy and eventually failure and dilation manifesting as cardiomegaly.  Long standing coarctation of the aorta may cause reverse 3 sign and rib notching.  
 

Tetralogy of Fallot (TOF)

TOF is associated with small or atretic pulmonary arteries which will cause the mediastinal shadow of the heart to be narrow.  Right ventricular hypertrophy, also associated with TOF will cause the cardiac apex to uplift.  The combination of narrow mediastinum and apical uplifting gives the classic "boot" shape of the heart on CXR.
 

Tricuspid Atresia (TrA)

Tricuspid atresia will force blood to shunt right to left across an atrial septal defect or a stretched PFO.  The RV size if the ventricular septum is intact will be small.  Non of these changes will cause appreciable changes on CXR.  However, these patients will have patent ductus arteriosus to allow pulmonary blood flow.  The blood flow to the lungs will typically be increased and this may manifest as engorged pulmonary vasculature.
In this CXR, cardiomegaly and increase PBF are present.
 

Pulmonary Atresia-Intact Ventricular Septum (PA-IVS)

PA-IVS is of 2 main types, the first is associated with severe tricuspid regurgitation.  These patients will have severely dilated right atrium and ventricle, manifesting as severe cardiomegaly by CXR.  On the other hand, those with no tricuspid regurgitation will have small right ventricles and no changes on CXR may be noted.  
 

Truncus Arteriosus (TA)

Patients with truncus arteriosus have narrow mediastinum due to 2 factors:  Absence of the typical 2 great vessels crossing each other in the mediastinal region and atretic thymus gland in those patients with associated DiGeorge syndrome.
In this CXR the mediastinum is narrow, sternal wires indicate surgical repair.
 

Total anomalous Pulmonary Venous Return (TAPVR)

In patients with TAPVR with anomalous return to superior vena cava (typical anatomy), the abnormal vertical vein, draining abnormal pulmonary venous to the innominate vein, then to the SVC will constitute a circular shadow above the heart giving the "snow man" appearance on CXR.
 

Dextrocardia

Dextrocardia may be an isolated finding with normal intracardiac anatomy.  On the other hand a variety of heart defects, may be present as well.  In this image the cardiac apex is rightwards while the abdominal contents appear to be normally positioned (situs solitus)