Blood and urine catecholamine concentrations after implantation of artificial heart

Plasma and urine epinephrine and norepinephrine concentrations were measured before and after implantation of an artificial heart in 20 calves and before and after thoracotomy in 3 control calves. All animals had similar preoperative plasma and urine catecholamine concentrations. During the first 4 postoperative days, plasma and urine epinephrine and norepinephrine concentrations were markedly elevated in all animals. However, calves with an artificial heart had significantly higher concentrations than control calves. Thereafter, catecholamine levels in control animals returned to preoperative levels, whereas epinephrine concentrations in artificial heart recipients remained elevated for 2 weeks and norepinephrine concentrations remained elevated for over a month. Two artifical heart recipeints survived longer than 2 months and had normal plasma and urine catecholamine concentrations from day 32 until a few days before being put to death. Although the mechanism in unclear, these findings suggest that early artificial heart function is associated with a significant metabolic stress which slowly disappears or becomes tolerable after one month.