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It is the reversing of left to right shunt in patients with atrial septal
defects, ventricular septal defects or patent ductus arteriosus.
Normally the left side of the heart carries
oxygenated blood to the rest of the body. Patients who have atrial septal
defects or ventricular septal defects or patent ductus arteriosus have an
open pathway between the right and left sides of the heart.
Since normally the left side is more powerful
the pressure inside it is higher. Hence the flow of blood takes place from
left to right, with oxygenated blood going to the right side through the
defect then to the pulmonary arteries then back again to the left heart.
However, if this recycling of blood carries on for some time it creates a load
on the right side of the heart and the pulmonary artery. One result of this continuing load is it
leads to thickening of the wall pulmonary arterioles (small branches of
the pulmonary artery). This leads to an increased backward pressure on the
right side. When the pressure in the right side of the heart exceeds the
pressure of the left side the blood shunting through the defects mentioned
above reverses direction. The result is disastrous as the blood in the right
side is de-oxygenated (hasn't passed through the lungs yet). Thus, instead
of the left side carrying oxygenated blood to the rest of the body it now
carries de-oxygenated blood.
The patient turns blue (cyanosis) as the tissues contain
deoxygenated blood; the red blood counts are highly elevated (polycythemia)
as the body tries to compensate the lack of oxygenated blood by
increasing blood production.
Paradoxical embolism may occur in a patients with ASD, VSD, PDA.
Symptoms in adult life consist of shortness of breath, chest pain, syncope,
and coughing blood. Other signs include clubbing of the fingers and toes.
1. Doppler ultrasound can diagnose the direction of the
2. Cardiac catheterization.
1. Surgical repair
In all patients, the degree to which pulmonary vascular resistance is
elevated before operation is a critical factor determining prognosis. Surgery
is useful only in mild cases of pulmonary hypertension. However, if a moderate
to severe increase in pulmonary vascular resistance exists preoperatively,
either no change or a progression of pulmonary vascular disease is common
2. Heart lung transplantation
Heart lung transplantation may offer the only cure.
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