BASICS OF CHEST X RAY-PART 4, THE HEART AND PERICARDIUM



This is the fourth Post in the series Chest X Ray Interpretation. I personally suggest to read the other three posts before proceeding

1.Chest X Ray Part 1- Normal Anatomy And ItsVariants
2. BASICS OF CHEST X RAY- PART 2 , EASY WAY TO INTERPRET CXR.
3.Basics of Chest X Ray Part 3- systematic approach, silhouette sign and Hidden areas in chest Xray

Heart and Pericardium
On a chest film only the outer contours of the heart are seen.
In many cases we can only tell whether the heart figure is normal or enlarged and it will be difficult to say anything about the different heart compartments.

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However it can be helpful to know where the different compartments are situated.
Left Atrium
    Most posterior structure.
    Receives blood from the pulmonary veins that run almost horizontally towards the left atrium.
    Left atrial appendage (in purple) can sometimes be seen as a small outpouching just below the pulmonary trunk.
    Enlargement of the left atrium results on the PA-view in outpouching of the upper heart contour on the right and an obtuse angle between the right and left main bronchus. On the lateral view bulging of the upper posterior contour will be seen.

Right Atrium
    Receives blood from the inferior and superior vena cava.
    Enlargement will cause an outpouching of the right heart contour.

Left Ventricle
    Situated to the left and posteriorly to the right ventricle.
    Enlargement will result on the PA-view in an increase of the heart size to the left and on the lateral view in bulging of the lower posterior contour.

Right Ventricle
    Most anterior structure and is situated behind the sternum.
    Enlargement will result on the PA-view in an increase of the heart size to the left and can finally result in the left heart border being formed by the right ventricle.
Left Atrium
    The upper posterior border of the heart is formed by the left atrium.
    Enlargement will result in bulging of the upper posterior contour

Left Ventricle
    Forms the lower posterior border.
    Enlargement will displace the contour more posteriorly.

Right Ventricle
    The lower retrosternal space is filled by the right ventricle.
    Enlargement of the right ventricle will result in more superior filling of this retrosternal space.

Left Atrium enlargement
This is a patient with longstanding mitral valve disease and mitral valve replacement.
Extreme dilatation of the left atrium has resulted in bulging of the contours (blue and black arrows).

Right ventricle enlargement
First study the PA and lateral chest film and then continue reading.

On these chest films the heart is extremely dilated.
Notice that it is especially the right ventricle that is dilated. This is well seen on the lateral film (yellow arrow).

There is a small aortic knob (blue arrow), while the pulmonary trunk and the right lower pulmonary artery are dilated.
All these findings are probably the result of a left-to-right shunt with subsequent development of pulmonary hypertension.
The location of the cardiac valves
is best determined on the lateral radiograph.
A line is drawn on the lateral radiograph from the carina to the cardiac apex.
The pulmonic and aortic valves generally sit above this line and the tricuspid and mitral valves sit below this line .

On this lateral view you can get a good impression of the enlargement of the left atrium.

Cardiac incisura


On the right side of the chest the lung will lie against the anterior chest wall.
On the left however the inferior part of the lung may not reach the anterior chest wall, since the heart or pericardial fat or effusion is situated there.
This causes a density on the anteroinferior side on the lateral view which can have many forms.
It is a normal finding, which can be seen on many chest x-rays and should not be mistaken for pathology in the lingula or middle lobe.

The explanation for the cardiac incisura is seen on this CT-image.
At the level of the inferior part of the heart we can appreciate that the lower lobe of the right lung is seen more anteriorly compared to the left lower lobe.

Pacemaker
There are different types of cardiac pacemakers.
Here we see a pacemaker with one lead in the right atrium and another in the right ventricle.

A third lead is seen, which is guided through the coronary sinus towards the left ventricle.
This is done in patients with asynchrone ventricular contractions.
Pacing both ventricles at the same time will lead to synchrone contractions and a better cardiac output.


Pericardial effusion
Whenever we encounter a large heart figure, we should always be aware of the possibility of pericardial effusion simulating a large heart.

On the chest x-ray it looks as if this patient has a dilated heart while on the CT it is clear, that it is the pericardial effusion that is responsible for the enlarged heart figure.
Especially in patients who had recent cardiac surgery an enlargement of the heart figure can indicate pericardial bleeding.

This patient had a change in the heart configuration and pericardial bleeding was suspected.
Ultrasound demonstrated only a minimal pericardial effusion.
Continue with the CT.
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There is a large pericardial effusion, which is located posteriorly to the left ventricle (blue arrow).
The left ventricle id filled with contrast and is compressed (red arrow).
At surgery a large hematoma in the posterior part of the pericardium was found.

Notice that on the anterior side there is only a minimal collection of pericardial fluid, which explains why the ultrasound examination underestimated the amount of pericardial fluid.

Here another patient who had valve-replacement.

Notice the large heart size.
There is redistribution of the pulmonary vessels which indicates heart failure.

Continue with the CT.
  

The CT-image shows a large pericardial effusion.

Always compare these post-operative chest films with the pre-operative ones.

Calcifications

Detection of calcifications within the heart is quite common.
The most common are coronary artery calcifications and valve calcifications.

Here we see pericardial calcifications which can be associated with constrictive pericarditis.
In this case there are calcifications that look like pericardial calcifications,
but these are myocardial calcifications in an infarcted area of the left ventricle.

Notice that they follow the contour of the left ventricle.

Pericardial fatpad

Pericardial fat depositions are common.
Sometimes a large fat pad can be seen (figure).

Necrosis of the fat pad has pathologic features similar to fat necrosis in epiploic appendagitis.
It is an uncommon benign condition, that manifests as acute pleuritic chest pain in previously healthy persons.

Pericardial cyst     
   
                                                                                                             

Pericardial cysts are connected to the pericardium and usually contain clear fluid.
The majority of pericardial cysts arise in the anterior cardiophrenic angle, more frequently on the rightside, but they can be seen as high as the pericardial recesses at the level of the proximal aorta and pulmonary arteries .
Most patients are asymptomatic.
On the chest x-ray it seems as if there is a elevated left hemidiaphragm.
On CT however there is a cyst connected to the pericardium

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