Cavo-atrial junction

Dr Henry Knipe et al.

The superior cavo-atrial junction, generally referred to as simply the cavo-atrial junction (CAJ), is the junction of the right lateral border of the superior vena cava (SVC) and the superior border of the right atrium.

It is an important landmark to recognise because it marks an optimum site for central venous catheter tip placement. 

Radiographic appearance

Plain radiograph

There are a variety of methods to estimate the position of the cavo-atrial junction on chest radiographs:

  • two vertebral body levels below the level of the carina 2
  • intersection of bronchus intermedius with the right heart border or inflection of the right heart border with the SVC contour 3
    • note: superior right heart border may not always be formed by the right atrium and may be formed by the right atrial appendage or left atrium 4
  • within one vertebral space either side of T5/6 4 
Thoracic anatomy
Chest x-ray
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Article information

rID: 29795
Systems: Chest, Cardiac
Section: Anatomy
Synonyms or Alternate Spellings:
  • Cavoatrial junction (CAJ)
  • Superior cavoatrial junction
  • Superior cavo-atrial junction

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Cases and figures

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    Figure 1: cavo-atrial junction
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