The Journal of Thoracic and Cardiovascular Surgery, Vol 71, 648-658, Copyright © 1976 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Successful prolonged heparinless venoarterial bypass in sheep
A Wakabayashi, CC Chen, PJ Mullin and JE Connolly
In order to investigate the safety of prolonged heparinless venoarterial
bypass (HL-VAB), we subjected 18 sheep to prolonged HL-VAB for up to 6
days. Three animals died of granulomatous lung abscess and one died from
intra-abdominal abscess. One animal died of generalized thromboembolism
secondary to mechanical damage of the nonthrombogenic coating occurring at
the time of cannulation. HL-VAB was successfully carried out in 13 sheep.
Although clots were found at all tubing connections where blood turbulence
occurred, only the previously mentioned animal showed evidence of
thromboembolism. Damage to the nonthrombogenic tubing exposed to the roller
pump head was seen in all animals, and its severity appeared to be related
to the duration of bypass. Scanning electron microscopic examination
revealed scattered platelet aggregates on the nonthrombogenic coated
surfaces without clinical evidence of embolization. Hematocrit values,
leukocyte counts, platelet counts, prothrombin time (PT), activated partial
thromboplastin time (PTT), thrombin time (TT), plasma fibrinogen levels,
and factor V and VIII levels remained unchanged, whereas free plasma
hemoglobin levels rose slightly during 6 days of HL-VAB. HL-VAB for up to 6
days appears to have little adverse effect on blood cells and blood
coagulation factors. For current clinical use, the nonthrombogenic coated
tubing circuit should be changed every 48 hours because of time-related
trauma to the coated tubing from the roller pump.