Search results
Results from the WOW.Com Content Network
A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. [1] This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles .
A left-to-right shunt is when blood from the left side of the heart goes to the right side of the heart. This can occur either through a hole in the ventricular or atrial septum that divides the left and the right heart or through a hole in the walls of the arteries leaving the heart, called great vessels.
A pulmonary shunt is the passage of deoxygenated blood from the right side of the heart to the left without participation in gas exchange in the pulmonary capillaries. It is a pathological condition that results when the alveoli of parts of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region.
Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect (typically by a ventricular septal defect, atrial septal defect, or less commonly, patent ductus arteriosus) causes pulmonary hypertension [1] [2] and eventual reversal of the shunt into a cyanotic right-to-left shunt.
However, it can also be used to detect other forms of right-to-left shunts including pulmonary arteriovenous malformations because it too needs agitated saline/contrast injected, but rather than imaging the heart, observes if any microemboli appear in the middle cerebral artery, an artery or the brain, following a valsalva maneuver. [7]
This reversal of the pressure gradient across the ASD causes the shunt to reverse – a right-to-left shunt. This phenomenon is known as Eisenmenger's syndrome. Once right-to-left shunting occurs, a portion of the oxygen-poor blood gets shunted to the left side of the heart and ejected to the peripheral vascular system. This causes signs of ...
This increases systemic vascular resistance and allows for a temporary reversal of the shunt. It increases pressure on the left side of the heart, decreasing the right to left shunt, thus decreasing the amount of deoxygenated blood entering the systemic circulation. [21] [22]
It is caused by structural defects of the heart such as right-to-left or bidirectional shunting, malposition of the great arteries, or any condition which increases pulmonary vascular resistance. The result may be the development of collateral circulation.