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Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart.Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this does not naturally close after birth it is referred to as a patent (open) foramen ovale (PFO).
These routes include moving through a patent foramen ovale (a congenital hole connecting the right and left atria of the heart), a ventricular septal defect (a congenital hole connecting the ventricles), or a pulmonary arteriovenous fistula, where arteries in the lungs connect directly to veins without capillaries in between.
Classic for a patent foramen ovale (PFO) or atrial septal defect (ASD). A PFO is lack of closure of the foramen ovale. At first, this produces a left-to-right heart shunt. This does not produce cyanosis, but causes pulmonary hypertension. Longstanding uncorrected atrial septal defects can also result in Eisenmenger syndrome.
In the presence of a right-to-left shunt of the heart, such as a patent foramen ovale, venous bubbles may enter the arterial system, resulting in an arterial gas embolism. [ 7 ] [ 57 ] A similar effect, known as ebullism , may occur during explosive decompression , when water vapour forms bubbles in body fluids due to a dramatic reduction in ...
The foramen ovale stays open because of the flow of blood from the right atrium to the left atrium. As the lungs expand, blood flows easily through the lungs and the membranous portion of the foramen ovale (the septum primum) flops over the muscular portion (the septum secundum). If the closure is incomplete, the result is a patent foramen ...
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.
An uncorrected left-to-right shunt can progress to a right-to-left shunt; this process is termed Eisenmenger syndrome. [3] This is seen in Ventricular septal defect, Atrial septal defect, and patent ductus arteriosus, and can manifest as late as adult life. This switch in blood flow direction is precipitated by pulmonary hypertension due to ...
The first is the foramen ovale (the valve present between them called eustachian valve) which shunts blood from the right atrium to the left atrium. The second is the ductus arteriosus which shunts blood from the pulmonary artery (which, after birth, carries blood from the right side of the heart to the lungs) to the descending aorta.