Therapeutic defibrinogenation by ancrod: effect on limb blood flow in peripheral vascular disease.
Reduction of blood viscosity by venesection may improve peripheral blood flow but similar haemorheological changes have not been conclusively demonstrated following reduction of plasma viscosity by defibrinogenation. Ancrod is a defibrinogenating enzyme from the venom of the Malayan pit viper. We studied six male patients with severe intermittent claudication before, during and after treatment with ancrod for 48 h. Ancrod was given by initial infusion of 2 U/kg over 6 h and four subsequent bolus i.v. injections of 2 U/kg. Skin blood flow in feet and toes were measured repeatedly by laser Doppler velocimetry and calf blood flow by electronic plethysmography both before and after 2 min arterial occlusion. Plasma fibrinogen [median (range)] fell from 2.3(1.4-3.9) to 0.1(0.1-0.3) g/l and plasma viscosity from 1.81(1.61-1.90) to 1.49(1.45-1.72) cp. Dorsal foot and toe skin blood (resting or post-ischaemic) flows were not changed significantly by ancrod. Resting calf blood flow fell significantly after 49 h treatment with ancrod (P less than 0.04). Brachial and ankle blood pressures remained unchanged and haematocrit was not changed. Thus, treatment with ancrod for 48 h did not improve peripheral blood flow in patients with peripheral vascular disease. The fall observed in calf blood flow could be related to increased circulating fibrin/fibrinogen high-molecular-weight complexes and degradation products.
Wiles
P G
PG
University Department of Medicine, General Infirmary, Leeds, UK.
Nelson
S R
SR
Hampton
K K
KK
Casali
B
B
Boothby
M
M
Prentice
C R
CR
D000328:Adult; D000368:Aged; D000721:Ancrod / Q000494:pharmacology / Q000627:therapeutic use*; D001783:Blood Flow Velocity; D001809:Blood Viscosity / Q000187:drug effects; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D005340:Fibrinogen / Q000037:antagonists & inhibitors* / Q000187:drug effects; D006801:Humans; D007383:Intermittent Claudication / Q000188:drug therapy* / Q000503:physiopathology; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply
D005338:Fibrin Fibrinogen Degradation Products; D005340:Fibrinogen; D000721:Ancrod