Human atrial noradrenaline content, hypothermic ischaemic arrest and parameters of left ventricular function

The noradrenaline (NA) content in tissue excised from the right atrium before and after hypothermic ischaemic arrest and subsequent coronary reperfusion was estimated biochemically and histochemically. The series consisted of 22 patients suffering from aortic valve disease. The NA concentration in the preoperative and postoperative samples was similar in all instances and it was clear that the right atrial myocardial NA content remained unchanged under conditions typical of an aortic valve replacement operation. The mean NA contents (microgram/g +/- SD) of the whole series before and after procedure were 2.0 +/- 1.1 and 2.2 +/- 1.5, respectively (p greater than 0.1 NS). Additionally, left heart catheterization was performed preoperatively in 11 patients with aortic valve disease, and certain left ventricular cardiocirculatory variables of contractility and failure were recorded. No statistically significant correlation could be found between the right atrial myocardial NA content and the left ventricular contractile state. However, left ventricular end-diastolic pressure presented a significant positive correlation with the NA content of right atrial myocardium (r = 0.65, p less than 0.02, n = 11). The problems encountered in weaning the heart off perfusion after aortic surgery can hardly be explained in terms of altered myocardial NA stores.