Decreased liberation of noradrenaline from the heart following cold crystalloid cardioplegia.

Exogenous catecholamine support is often needed soon after termination of cardiopulmonary bypass even when appropriate cardioplegia has been used. To study the effect of hypothermic cardioplegic ischemia and reperfusion on the activity of the cardiac sympathetic nervous system, plasma noradrenaline concentration in the coronary sinus and general circulation was measured in six patients undergoing valve replacement for nonischemic mitral disease. Before cardiopulmonary bypass and cardioplegia the release of noradrenaline from the heart was greater than the mean systemic release. After ischemia, during reperfusion, the heart tended to extract noradrenaline, and 10 min after termination of bypass the plasma noradrenaline gradient over the heart remained less than pre-bypass. The results indicated decreased activity of the cardiac sympathetic nervous system, which may explain the frequent need for catecholamine support.