Activity of sympathetic nerves in heart during cardiopulmonary bypass in patients.

The sympathetic nerve activity in heart during cardiopulmonary bypass was studied in 20 patients. The rate of release of dopamine-beta-hydroxylase from cardiac nerves was used as an indicator. It was found that the thoracotomy alone does not represent such a stimulus which would lead unambiguously to sympathetic overactivity in heart. Cardiopulmonary bypass represents, on the other hand, an intensive sympathomimetic stimulus, as it was demonstrated by significnat increase of coronary A-V difference negativity of dopamine-beta-hydroxylase as early in 15th minute of its duration. The washout of enzyme to the end of 30 min. duration of bypass still increased. After finishing of bypass the coronary A-V diff. of dopamine-beta-hydroxylase again decreased.