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The right ventricle hypertrophies to compensate for this pulmonary hypertension, so the right ventricular pressure becomes higher than the pressure in the left ventricle. Because of this switch in the pressure gradient, blood starts flowing right to left, forming a right-to-left shunt. As with any right-to-left shunt, there is decreased blood ...
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.
If left untreated, the disease may progress from left-to-right shunt (acyanotic heart) to right-to-left shunt (cyanotic heart), called Eisenmenger's syndrome. Pulmonary hypertension is a potential long-term outcome, which may require a heart and/or lung transplant. Another complication of PDA is intraventricular hemorrhage. [citation needed]
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.
Larger defects may eventually be associated with pulmonary hypertension due to the increased blood flow. Over time this may lead to an Eisenmenger's syndrome the original VSD operating with a left-to-right shunt, now becomes a right-to-left shunt because of the increased pressures in the pulmonary vascular bed.
Persistent pulmonary hypertension of the newborn occurs when the circulatory system of a newborn baby fails to adapt to life outside the womb; it is characterized by high resistance to blood flow through the lungs, right-to-left cardiac shunting and severe hypoxemia. [15]
Although the mechanism is still unclear, it is thought to be caused by right to left shunting of blood flow due to an anatomic defect allowing communication between right and left-sided circulation, such as an atrial septal defect, patent foramen ovale, or pulmonary atrioventricular malformations, and a functional component that causes blood to ...
It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heart pressure, a biological or artificial heart valve or both. The presence of a shunt may also affect left and/or right heart pressure either beneficially or detrimentally.