- Right-to-left shunt
A right-to-left shunt is a cardiac shunt which allows, or is designed to cause,
blood to flow from theright heart to theleft heart . [DorlandsDict|seven/000096626|right-to-left shunt] This terminology is used both for the abnormal state in humans and for normal physiological shunts inreptile s.Human medical
A right-to-left shunt occurs when:
#there is an opening or passage between theatria , ventricles, and/orgreat vessels ; "and",
#right heart pressure is higher than left heart pressure and/or the shunt has a one-way valvular opening.The most common cause of right-to-left shunt is the
Tetralogy of Fallot , a congenital cardiac anomaly characterized by four co-existing heart defects. The four defects include:#
Pulmonary stenosis (narrowing of the pulmonary valve and outflow tract, obstructing blood flow from the right ventricle to the pulmonary artery)
#Ventricular septal defect (defect in the ventricular septum, which divides the left and right ventricles of the heart)
#Overriding aorta (aortic valve is enlarged and appears to arise from both the left and right ventricles instead of the left ventricle, as occurs in normal hearts)
#Rightventricular hypertrophy (thickening of the muscular walls of the right ventricle)A right to left shunt frequently causes
hypoxemia .Reptiles
Because most reptiles have a single ventricle and all reptiles have both a right aortic arch and a left aortic arch, all reptiles have the capacity for right-to-left shunt. Fact|date=August 2008
References
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