Effects of adrenaline on ventricular function and coronary haemodynamics in relation to catecholamine handling in...

We investigated cardiovascular and coronary responses to intravenous infusions of adrenaline, which raised arterial concentrations in a stepwise fashion from basal to about 5-6 nmol.l-1, in 11 non-rejecting heart transplanted patients, and in eight intact innervated subjects. Cardiac adrenaline extraction and noradrenaline release rate were also measured. The transplanted patients showed larger increases in heart rate (36 +/- 11% vs 16 +/- 6%, P < 0.0001) and cardiac index (80 +/- 30% vs 56 +/- 19%, P < 0.05), while stroke volume increments were similar in the two groups (32 +/- 17% vs 35 +/- 13%). The study groups did not differ with respect to changes in arterial pressure, cardiac work or peripheral resistances. Coronary sinus blood flow increased to a greater extent in the transplanted group (75 +/- 35% vs 48 +/- 31%, P < 0.05) and myocardial oxygen consumption also tended to increase more in these patients (78 +/- 42% vs 48 +/- 34%, NS). Myocardial adrenaline extraction was greatly reduced in the transplant patients (-6 +/- 25% vs 64 +/- 18%, P < 0.001), while forearm adrenaline extraction was similar in the two groups (41 +/- 22% vs 40 +/- 23%, NS). Cardiac noradrenaline overflow tended to be lower in the transplanted group (12 +/- 62 vs 48 +/- 43 pmol.min-1, NS). There was a wide range of noradrenaline overflow values (-64 to 147 pmol.min-1) and definite high values in three patients. Cardiac noradrenaline overflow was not correlated to heart rate responsiveness to adrenaline. We conclude that patients with cardiac transplantation respond to adrenaline with exaggerated increases in heart rate and thus in cardiac output. High values of cardiac noradrenaline overflow are seen in some transplant recipients and may suggest reinnervation. Signs of reinnervation are not associated with consistently lower heart rate responses to beta-adrenergic stimulation.