Pulmonary-to-systemic shunt
Encyclopedia
A pulmonary-to-systemic shunt is a cardiac
shunt
which allows, or is designed to cause, blood
to flow
from the pulmonary circulation
to the systemic circulation
. This occurs when:
A pulmonary-to-systemic shunt functions as follows:
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
shunt
Shunt (medical)
In medicine, a shunt is a hole or a small passage which moves, or allows movement of fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either biological or mechanical.* Cardiac shunts may be described as...
which allows, or is designed to cause, blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
to flow
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
from the pulmonary circulation
Pulmonary circulation
Pulmonary circulation is the half portion of the cardiovascular system which carries Oxygen-depleted Blood away from the heart, to the Lungs, and returns oxygenated blood back to the heart. Encyclopedic description and discovery of the pulmonary circulation is widely attributed to Doctor Ibn...
to the systemic circulation
Systemic circulation
Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...
. This occurs when:
- there is a passage between two or more of the great vesselsGreat vesselsGreat vessels is a term used to refer collectively to the four large vessels that bring blood to and from the heart. These are:*Superior vena cava*Inferior vena cava*Pulmonary artery*AortaAll four pulmonary veins are considered apart of the great vessels...
; and, - pulmonic pressureBlood pressureBlood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
is higher than systemic pressure and/or the shunt has a one-way valvularHeart valveA heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...
opening.
A pulmonary-to-systemic shunt functions as follows:
- right-to-left in the absence of arterioventricular discordance.
- left-to-right if the great vesselsGreat vesselsGreat vessels is a term used to refer collectively to the four large vessels that bring blood to and from the heart. These are:*Superior vena cava*Inferior vena cava*Pulmonary artery*AortaAll four pulmonary veins are considered apart of the great vessels...
are transposed.