Superior cavoatrial junction

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The superior cavoatrial junction (SCAJ), generally referred to as simply the cavoatrial 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 recognize because it marks an optimum site for central venous catheter tip placement.

Terminology

There is also an inferior cavoatrial junction at the junction between the inferior vena cava (IVC) and the right atrium. However this term is less commonly used/seen and generally cavoatrial junction is understood to mean the superior one.

Radiographic appearance

Plain radiograph

There are a variety of methods to estimate the position of the cavoatrial junction on chest radiographs:

  • two vertebral body levels below the level of the carina
  • intersection of bronchus intermedius with the right heart border or inflection of the right heart border with the SVC contour
    • 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
  • within one vertebral space either side of T5/6