Increased blood flow to lower limbs after plasma exchange in two patients with familial hypercholesterolemia.

Leg blood flow was measured before and 1 and 7 days after plasma exchange by venous occlusion plethysmography in a 9-year-old girl with homozygous familial hypercholesterolemia and in a 41-year-old man with heterozygous familial hypercholesterolemia. In the first patient the plasma cholesterol level was reduced from 890 mg/dl to 532 mg/dl and 666 mg/dl 1 and 7 days after plasma exchange. In the second patient plasma cholesterol decreased from 596 mg/dl to 342 mg/dl and 480 mg/dl, respectively. Leg arterial flow increased from 8.5 ml/min/l of leg volume to 19.1 and 19.5 ml/min/l in the first patient and from 6.6 ml/min/l to 18.0 and 21.8 ml/min/l in the second. No change was observed in haematocrit and total globulin concentration, which are known to play an important role in blood viscosity and flow. It is concluded that plasma exchange, possibly by decreasing plasma cholesterol concentration in patients with familial hypercholesterolemia, is associated with improved arterial flow to lower limbs and it is suggested therefore that some beneficial effect might be found also in other vascular beds.