Reading an Abnormal Chest X-ray | Heart and Diaphragm | Part III Basics

in StemSocial4 years ago

Hey everyone, Welcome once again to my new article. This is Part- III of Basics of Reading an X-ray series. You can see my previous article on this series from these links(Part-I, Part-II). In this part, we will discuss the abnormal finding in the chest X-ray, more specifically the pathologies in the heart and lungs. Airways and bones are covered in my previous article. All these topics come under the "ABCDE" system, which basically stands for Airways, Bones, Cardiac, Diaphragm, and Effusion(Lungs). This is a systematic way of interpreting a chest X-ray.

The aim of this article is to give you a basic idea of the most common pathologies that you can find in heart and Diaphragm in an X-ray and how you can assess them. Let's get right into the topic now.

Abnormalities in Cardiac silhouette. (Heart)

Before the abnormalities, we must know about the normal structures in the heart. I covered this one in the Part-I. Here in the image, you can see normal heart structures seen in a normal X-ray.


[Normal Chest x-ray with heart markings, Wikimedia by Mikael Häggström,licensed under CC0 1.0 *free to reuse and modify*]


Now, that most common abnormalities we look for in the heart are as follows:

  1. Cardiomegaly(Enlarged Heart)
  2. Pericardial Effusions
  3. Dextrocardia ( Heart in the opposite side)
  4. Different Mediastinal Masses

Cardiomegaly(Enlarged Heart)

Cardiomegaly is a very commonly observed heart pathology and it means enlarged heart. The cause can vary from patient to patient but generally, the most common cause can be high blood pressure or coronary artery blockage. the coronary artery carries the blood to the heart muscles. This enlarged heart can be dangerous as it can lead to heart failure. It's not a disease, rather it's a condition that results from other diseases.


[Enlarged Heart with Pacemaker, Wikimedia by
James Heilman, MD, licensed under
CC BY-SA 3.0]


In an X-ray, Cardiomegaly can be easily interpreted. Other tests are needed to find the cause, of course. An enlarged heart is interpreted by calculating the Cardio-thoracic ratio. this means the comparison of the transverse diameter of the heart to the diameter of the widest part of the thoracic cage. This is done in a PA view, using the widest part of the cage including the lung pleura(covering of lungs) and excluding the skin margins. If the ratio is found to be more than 50%, then cardiomegaly can be suspected. Of course, X-ray is a great help, but it can be used alone for the diagnosis. Other investigations such as ECG, CT scan, stress test, blood test, biopsy, etc are also needed if suspected.

Pericardial Effusion

This means the accumulation of fluid in the pericardial cavity. Also known as fluid around the heart. There is very little space in the pericardial cavity, thus the accumulation of fluid leads to raised pressure and adversely affects the heart. when these conditions affect the heart severely, it's known as Cardiac tamponade. This cause of this condition is irregular production and re-absorption of the pericardial fluid, which can happen in various diseases like, viral infections, pericarditis, cancers, etc.





[Massive pericardial effusion, Wikimedia by James Heilman, MD, licensed under CC BY-SA 4.0]

This condition can be easily mistaken for cardiomegaly, but the heart is not enlarged in this case. There is one specific thing to look for to identify this pathology known as "Water bottle appearance". The enlarged pericardial cavity looks like a water bottle.

As you can see in the image, the enlargement is taking an area of more than 60%. Also, give the shape like a water bottle. You might argue, that doesn't look like a water bottle at all but, the name was given when leather water bottles were used not plastic.

Dextrocardia

Well, dextrocardia means, the heart is mirrored and lies on the opposite side. It's not a disease and is asymptomatic in most cases but sometimes can show symptoms and can be associated with some heart defects. This condition is quite rare, with an incidence of 1 person per 12000. There are two forms of dextrocardia.


[Dextrocardia situs inversus, Wikimedia by
Nevit, licensed under
CC BY-SA 3.0]

    1. Dextrocardia of embryonic arrest
    2. Dextrocardia situs inversus

Dextrocardia of embryonic arrest: In this form, the heart is simply pushed to the right side slightly, which might be noticeable sometimes in an X-ray. But, this condition is related to severe heart defects.

Dextrocardia situs inversus: In this condition, the heart is mirrored to the opposite side. Thus, we observe it on the right side rather than left. This one is really associated with severe heart defects.

As, you can clearly see in an X-ray, the apex of the heart in on the right side, looking like a mirrored heart and quite easy to interpret.

Abnormalities in the Diaphragm

The diaphragm is a dome-shaped organ, which basic function is to help in respiration and separate chest cavity from the abdominal cavity. The right side of the diaphragm is seen slightly seen above the left side, because of the liver lying directly beneath it. They are seen as a flat structure in an X-ray, but they are not, they are 3 dimensional, dome-shaped, and highly curved structures. Also, a pocket of air is seen beneath the left side, which indicates the pocket of air in the stomach, and is perfectly normal. This pocket of air is known as the "Gastric bubble". In a normal X-ray, the diaphragm must be indistinguishable from the liver beneath it.


Visualizing Diaphragm by Theresa knott
, Wikimedia, licensed under CC BY-SA 3.0






[Normal Chest x-ray with heart markings by Mikael Häggström, Wikimedia licensed under
CC0 1.0 *free to reuse and modify*]

....

..

The most common abnormalities in the diaphragm are as follows:

  1. Diaphragmatic Rupture
  2. Diaphragmatic Hernia
  3. Raised hemidiaphragm
  4. Phrenic nerve palsy

Diaphragmatic Rupture and Hernia

This means, a tear in the diaphragm and most commonly is caused due to trauma. This is mostly due to blunt trauma. Since the pressure in the chest cavity is always less than the abdominal cavity, the ruptured diaphragm is often associated with herniation of abdominal organs into the thoracic cavity, which can be pretty deadly because this can interfere with breathing and blood supply of the organs.

Image: Dipgragmatic rupture by Biomed central, Wikimedia licensed under CC BY 2.0



As you can see in the X-ray, the left hemithorax is not visible at all, which means it is ruptured. A hazy white structure is seen instead of left hemidiaphragm, which is actually spleen, that herniated into the thoracic cavity also, you can observe the right shift of the heart due to abdominal pressure. This can be also seen as raised left hemidiaphragm.


. . .

Raised Hemidiaphragm

As I mentioned, right hemidiaphragm is a little bit above the left hemidiaphragm. But it's just a tiny bit if it is raised more or higher, then there might be some pathologies related to it. You can see it clearly, in the above-mentioned image under the diaphragmatic rupture heading. The left hemidiaphragm is raised very high due to its rupture and spleen herniation into the chest cavity. Also, other causes include phrenic nerve palsy.

Phrenic Nerve palsy

Phrenic nerve palsy or paralysis is caused by the lesion anywhere along the path of the phrenic nerve. It travelers through the neck and prices the diaphragm. And is one of the most common causes for the one-sided raised diaphragm. The clinical presentation is associated with the underlying cause but some of the most common ones are, difficulty breathing while sleeping, shortness of breath with regular exercise. The lesion can be because of any kind of carcinoma or trauma.

Diaphragmatic rupture with phrenic nerve palsy by Biomed central, Wikimedia licensed under
CC BY 2.0

In an Xray, to visualize phrenic nerve palsy, we look for raised hemidiaphragm. Any side can be raised. If the left hemidiaphragm is raised higher or, the right hemidiaphragm is raised from than 20 millimeters than left, then it is suspicious of phrenic nerve palsy with many other conditions too. This is the Xray of the trauma patient, with diaphragmatic rupture and phrenic nerve paralysis. See how the right hemidiaphragm is raised more than 20 millimeters or 2 cm.

That's it for this article guys.

I hope you liked it.

*All the images used are copyright free and are provided with appropriate credits*

References:

https://en.wikipedia.org/wiki/Abdominal_trauma
https://www.mayoclinic.org/diseases-conditions/enlarged-heart/symptoms-causes/syc-20355436
https://en.wikipedia.org/wiki/Pericardial_effusion
https://radiopaedia.org/articles/dextrocardia
https://en.wikipedia.org/wiki/Diaphragmatic_rupture
https://medlineplus.gov/ency/article/001135.htm









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