腳比手 cyanosis 更嚴重

Patent ductus arteriosus (PDA), caused by failure of the embryologic ductus arteriosus to close after birth, represents 10% of cases of congenital heart disease. The most common symptoms include dyspnea, exercise intolerance, peripheral edema, and palpitations, although 25 to 40% of patients with a PDA are asymptomatic. With PDA, in contrast to many other shunts, continuous left-to-right shunting may occur because of the large resistance and the pressure gradient that normally exists between the systemic and pulmonary vascular beds. However, if left untreated, some patients may develop serious cardiac pathology — either elevated pulmonary artery pressure from the increased pulmonary blood flow due to the shunt, eventually leading to increased pulmonary vascular resistance and severe pulmonary hypertension or left heart volume overload due to the ductal shunt, eventually resulting in left-sided heart failure.

Morning Report Questions
Q: What is Eisenmenger's syndrome?
A: Eisenmenger's syndrome refers to right-to-left cardiac shunting with cyanosis. This syndrome develops as a serious consequence of patent ductus arteriosus when pulmonary systolic pressure equals or exceeds the aortic pressure, and a right-to-left shunt ensues.

Q: What type of cardiac anomaly might exist if a patient has cyanosis of the toenails and not the fingernails?
A: When the physiology of Eisenmenger's syndrome is due to patent ductus arteriosus (right-to-left shunting and cyanosis), the oxygen saturation in the descending aorta is reduced. As a result, physical examination may reveal increased cyanosis of the toenails as compared with the fingernails.

Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008