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Hi Cynthia

Changed the order a little – Apologies –

You can change/edit if you want  if you want

I started with the basics –
Where are all the chambers
Rule of thirds
The LV since it s most common
The RV – uncommon
The LA – very common but mostly only appreciated on the lateral when very big eg mitral stenosis Elevation of the left main stem bronchus is not commonly seen but it is an important finding
RA hardly ever seen

The LATERAL EXAMINATION – Normal and Abnormal

THE CV STRUCTURES  VISIBLE ON THE LATERAL EXAM –

A normal lateral examination of the chest X-ray is shown to exemplify the positioning of the cardiac chambers showing the right ventricular outflow tract (RVOT) anteriorly, the left atrium (LA) posteriorly and superiorly, the left ventricle (LV) posteriorly and inferiorly and the inferior vena cava (IVC) as a separate shadow posterior to the LV.
Ashley Davidoff MD

RULE OF 1/3 rds

  • Normal Anteriorly
    • RV takes up 1/3 of retrosternal space ((Sternomanubrial  jn to xiphi)
  • Inferiorly
    • LV takes up 1/3 of the hemidiaphragm
  • Posteriorly
    • LA 1/3, LV 2/3
The rule of thirds on the lateral examination states that;
the anterior border of the chest is divided into thirds; 1/3 for the RVOT and 2/3 for the retrosternal air space
the posterior border of the heart is divided into thirds; 1/3 for the LA and 2/3 for the LV.
the diaphragmatic border is divided into thirds; 1/3 for the LV and 2/3 for the rest of the diaphragm
Ashley Davidoff MD
15416C02Wlateral.8 rule of thirds
  • Abnormal
      • Anteriorly
        • RVE
          • RV > 1/3 of retrosternal space
      • Posteriorly
        • LAE
          • LA >1/3 of posterior heart border
          • Also elevates left main stem bronchus
Normal vs Abnormal – Left Ventricular Enlargement

Assessment of the Size of the left Ventricle (LV) on the Lateral CXR
Lateral examination of a chest x-ray (CXR) shows the normal in the upper row (a,b) and the abnormal and enlarged in the bottom row (c,d).
The objective evaluation is based on the relative positioning and size of the LV (white arrowhead) in relation to the IVC, (blue arrowhead), and the left hemidiaphragm (pink arrowhead)
Ashley Davidoff MD
15416C02Wlateral LV01L.8

RVE

NORMAL and RVE
The normal lateral CXR (a,b), shows anterior and superior border of the heart (anterior white arrowhead) occupying 1/3 of the border between the sternomanubrial junction and the diaphragm.
The posterior and inferior white arrowhead shows the posterior border of the heart occupied by the RV taking up 1/3 of the distance of the diaphragm.
Images c and d represent left ventricular enlargement showing that the LV occupies about half the length of the diaphragm, (red arrowhead) while the retrosternal distance is unchanged and normal (white arrowhead).
Ashley Davidoff MD

Normal vs Abnormal  – RVE and LAE

LATERAL EXAMINATION RVE AND LAE ? MITRAL STENOSIS PULMONARY HYPERTENSION AND COR BOVINUM
71 year old Asian female with rheumatic heart disease dominated by calcific mitral stenosis mild MR, moderate tricuspid regurgitation 

Right Atrial Disease on the Lateral _ Only when it is very enlarged

 

Where is the Right Atrium?

RIGHT ATRIUM (RA) on the LATERAL
In the normal patient the RA is not border forming and is not visible. It lies to the right and slightly inferior and anterior to the left atrium, posterior and superior to the right ventricle, and to the right and superior to the left ventricle
Ashley Davidoff MD
  • Axial Imaging Explaining why the RA cannot be see on the Lateral –
    • since it is neither anterior nor posterior border forming
NORMAL CARDIAC ANATOMY ON A GATED CT SCAN
Axial images through the RA show the right atrial appendage in the top row and the body of the RA in the bottom row, neither of which would be visible on the lateral exam.
Ashley Davidoff MD
  • When the RA enlarges-
    • it moves laterally and anteriorly see CT below so that it can now be an anterior border forming structure
DOMINANT RIGHT ATRIAL ENLARGEMENT CT SCAN ? RETROSTERNAL AIRSPACE OCCUPIED MOSTLY BY THE RA
83-year-old male with significantly enlarged right atrium, as well as a mildly enlarged left atrium with evidence of CAD, atrial fibrillation and hypertension.
On CT scan the right atrium and appendage (blue overlay (b,d,f) are positioned against the anterior chest wall and sternum (red arrowheads). On the superior most images (b,d) the RV is not present and only takes up a retro-sternal position alongside the right atrium on the most inferior image (f)
Ashley Davidoff MD
RAE on the Lateral
DOMINANT RIGHT ATRIAL ENLARGEMENT. LATERAL EXAMINATION
83-year-old male with significantly enlarged right atrium, as well as a mildly enlarged left atrium with evidence of CAD, atrial fibrillation and hypertension.
On the lateral CXR, the right atrium the blue line overlay indicates the position of the RV against the anterior chest wall. In addition, the right atrial appendage is so large (see CT below) that it lies against the sternum. The RA therefore occupies the entire retrosternal air space and results in decrease of the retrosternal airspace. This is the rare instance when the RA shares with, but dominates the anterior retrosternal position with the RV.
Ashley Davidoff MD
DOMINANT RIGHT ATRIAL ENLARGEMENT
83 year old male with significantly enlarged right atrium, as well as a mildly enlarged left atrium with evidence of CAD, atrial fibrillation and hypertension.
On CT scan the right atrium is positioned against the anterior chest wall. In addition, the right atrial appendage is so large that it lies against the sternum as well resulting in a decrease in the retrosternal air space. On the lateral, the cardiac shadow takes up more than 1/2 of the diaphragm. In this uncommon instance this finding is caused by the enlarged right atrium rather than LVE
Ashley Davidoff MD

 

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Davidoff  with Notes Scales and Music of the Axial Imaging of the Heart