Wednesday, July 8, 2009

what is the pathophysiology behind clubbing of fingers in a child with congenital heart disease

what is the pathophysiology behind clubbing of fingers in a child with congenital heart disease?
how do you explain clubbing?
Medicine - 2 Answers
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1 :
clubbing is a result of the child's lack of O2 to the ends of the peripheral system. The child does not have sufficient oxygen carrried in the blood and the toes and fingers can "club" in the process. The physiological process is a thicking in the area to protect the already fragile capillaries and their low oxygen levels.
2 :
The lack of O2 to the distal extremities was the common theory in the past (the idea being the elaboration of things like VEGF in the distal extremities). Now the hot theory is that it's caused by the action of platelet clumps and megakaryocytes that get lodged in the distal capillary beds. The idea is that normally, circulating platelet clumps and megakaryocytes get lodged in and broken up in the pulmonary vasculature. In congenital heart defects that include a right-to-left shunt, these can bypass the lungs and remain in circulation. When they get lodged in the distal capillary beds they release platelet derived growth factor (PDGF) which stimulates collagen production around the capillaries. The theory is also valid for bacterial endocarditis in which platelet clumps can come off from the valvular vegetations (or other thrombogenic foci like aneurysmal plaques

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