Revision 15 for 'Cardiovascular shunts'

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Cardiovascular shunts

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.

Left-to-right shunt

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:

Right-to-left shunt

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:

Circular shunt

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 4-7.

Examples that have been described in the literature include:

Radiographic features

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

See also

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