Cardiac shunt

In cardiology, a cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system.

[2] Blood enters the upper right atrium, is pumped down to the right ventricle and from there to the lungs via the pulmonary artery.

A cardiac shunt is when blood follows a pattern that deviates from the systemic circulation, i.e., from the body to the right atrium, down to the right ventricle, to the lungs, from the lungs to the left atrium, down to the left ventricle and then out of the heart back to the systemic circulation.

In isolation, these defects may be asymptomatic, or they may produce symptoms which can range from mild to severe, and which can either have an acute or a delayed onset.

Evaluation can be done during a cardiac catheterization with a "shunt run" by taking blood samples from superior vena cava (SVC), inferior vena cava (IVC), right atrium, right ventricle, pulmonary artery, and system arterial.

Samples from the SVC & IVC are used to calculate mixed venous oxygen saturation using the Flamm formula and Qp:Qs ratio where

is the mixed-venous The Qp:Qs ratio is based upon the Fick principle and it is reduced to the above equation and eliminates the need to know cardiac output and hemoglobin concentration.