Effect of cold ischaemic arrest and subsequent coronary reperfusion on the intrinsic adrenergic innervation and neural noradrenaline of the atrial myocardium during aortic valve replacement.

The effect of cold ischaemic arrest (aortic cross-clamping for 50-70 min during general hypothermia of +30 degrees C, associated with local cardiac cooling with +4 degrees C saline solution) and subsequent coronary reperfusion (20-30 min) on the intrinsic adrenergic innervation of the right atrial myocardium, was studied in 10 patients in the course of prosthetic aortic valve replacement using the glyoxylic acid-induced fluorescence histochemical method. No clear changes were observed: (a) the morphological integrity of the intrinsic adrenergic nerve net remained intact, (b) no obvious depletion occurred in the neural noradrenaline level, (c) the procedure did not affect the "droplet fibres" (i.e. huge axonal accumulations of noradrenaline). Thus, the common need for catecholamine support during and after weaning off from cardiopulmonary bypass does not seem to be explained by damage to the adrenergic axons or depletion of the adrenergic neurotransmitter noradrenaline.