abnormal blood circulation cardiovascular shunt 2020-09-11T06:43:51Z cardiac shunt an abnormal communication (shunt) between the right and left sides of the heart or between the systemic and pulmonary vessels, allowing blood to flow directly from one circulatory system to the other; 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); rarely, the shunted blood returns to the same cardiac chamber without traversing a capillary bed (i.e. circular shunt); most commonly shunts are the result of congenital heart disease MPheno.ontology MP:0031128