Cardiovascular shunts

Dr Owen Kang and Dr Henry Knipe et al.

Cardiovascular (cardiac) shunts are abnormal connections between the pulmonary and systemic circulations. Most commonly they are the result of congenital heart disease.

Blood can either be shunted from the systemic circulation to pulmonary circulation (i.e. 'left-to-right shunt') or between the pulmonary circulation and systemic circulation (i.e. 'right-to-left shunt') 1-4. Rarely, the shunted blood returns to the same cardiac chamber without traversing a capillary bed, termed a 'circular shunt' 5-7.

In a left-to-right shunt oxygenated blood flows directly from the systemic circulation to the pulmonary circulation, which results in decreased tissue oxygenation through reduced cardiac output 1-4. Causes include 1-4:

In a right-to-left shunt deoxygenated blood flows directly from the pulmonary circulation to the systemic circulation, decreasing tissue oxygenation by reducing the oxygen content of systemic arterial blood 1-4. Causes include 1-4:

A useful mnemonic to remember some of the cardiac causes of a right-to-left shunt can be found here.

In most left-to-right or right-to-left cardiovascular shunts, shunted blood returns to the same chamber after traversing a capillary bed (either pulmonary or peripheral), if this does not occur then the term 'circular shunt' can be employed 5. Such shunts are generally present in complex congenital heart defects 5-7.

Examples that have been described in the literature include:

Imaging findings vary depending on the underlying etiology, please see articles listed above for further details.

Congenital heart disease

There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorized, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.

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Article information

rID: 35303
Section: Gamuts
Synonyms or Alternate Spellings:
  • Cardiac shunts
  • Cardiac shunting
  • Cardiovascular shunt
  • Cardiac shunt
  • Intracardiac shunt
  • Intracardiac shunts

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Cases and figures

  • Case 1: PAPVR
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  • Cardiac CT transa...
    Case 2: ASD
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  • Case 3: pulmonary AVM
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  • Case 4: VSD
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  • Case 5: SVC ostium obstruction with secondary right-to-left shunt
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