Mediastinal Shape
February 15th, 2021
On this page:Right Atrial EnlargementRight Ventricular EnlargementLeft Atrial EnlargementLeft Ventricular EnlargementBoot-Shaped HeartWater Bottle-Shaped Heart
Overview
The cardiac silhouette is normally ovoid in apperance, with the apex pointing toward the left.
Right Atrial Enlargement
Look For
- Bulging of the right side of the heart shadow.
Causes of Right Atrial Enlargement
- Cor pulmonale - pulmonary arterial hypertension, chronic lung disease, chronic pulmonary embolism
- Valvular disease - tricuspid stenosis, tricuspid regurgitation
- Congenital heart disease - atrial septal defect, tetralogy of Fallot
Right Ventricular Enlargement
Look For
- An up-turned apex
- Loss of space between the cardiac shadow and the sternum on lateral chest x-ray
Causes of Right Ventricular Enlargement
Hypertrophy
- Cor pulmonale - pulmonary arterial hypertension, chronic lung disease, chronic pulmonary embolism
- Valvular disease - tricuspid regurgitation, mitral stenosis
- Congenital heart disease - atrial septal defect, ventricular septal defect, tetralogy of Fallot
Dilation
- Dilated cardiomyopathy - familial, ischaemic, alcoholic, viral myocarditis, drugs, connective tissue disease, tachycardia-mediated, peripartum
Other
- Infiltrative disease - haemochromatosis, amyloidosis, sarcoidosis
- Hyperdynamic state - anaemia, hyperthyroidism, obesity, AV fistula
- Arrhythmogenic right ventricular cardiomyopathy
- Constrictive pericarditis
Left Atrial Enlargement
Look For
- Double density sign - a double cardiac border on the right side, due to the left atrium projecting behind the right atrium
- Splaying of the carina with superior displacement of the left main bronchus
- Slight bulging of the upper left cardiac border
Causes of Left Atrial Enlargement
- Hypertensive heart disease
- Valvular disease - mitral stenosis, aortic stenosis, mitral regurgitation
- Hypertrophic (obstructive) cardiomyopathy
- Aortic coarctation
Left Ventricular Enlargement
Look For
- Displacement of the left cardiac border laterally, inferiorly and posteriorly
- Rounded cardiac apex
Causes of Left Ventricular Enlargement
Hypertrophy
- Physiologic - athletes, pregnancy
- Hypertensive heart disease
- Valvular disease - aortic stenosis, aortic regurgitation, mitral regurgitation
- Hypertrophic (obstructive) cardiomyopathy
- Aortic coarctation
Dilation
- Dilated cardiomyopathy - familial, ischaemic, alcoholic, viral myocarditis, drugs, connective tissue disease, tachycardia-mediated, peripartum
Other
- Infiltrative disease - haemochromatosis, amyloidosis, sarcoidosis
- Hyperdynamic state - anaemia, hyperthyroidism, obesity, AV fistula
Boot-Shaped Heart
Look For
- An up-turned apex (due to right ventricular hypertrophy) with a concave appearance of the main pulmonary artery.
Significance
- A sign of tetralogy of Fallot.
Water Bottle-Shaped Heart
Look For
- Diffuse enlargement of the cardiac shadow with a globular appearance.
Significance
- Classically a sign of large pericardial effusion.
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