Hemodynamic and emotional responses to a psychological stressor after cardiac transplantation

Because cardiac transplantation entails neuronal decentralization, cardiac responses to a psychological stressor in transplant patients would be expected to rely on circulating hormonal factors and therefore to be delayed and prolonged. We tested this prediction by comparing stress responses after transplantation with those in patients with coronary artery bypass grafts (to control for experience of surgery) or heart failure (to control for heart disease).

Fifty-six transplantation patients, 66 bypass patients, and 40 patients with heart failure underwent a 10-minute, computer-generated, Stroop color-word conflict test. Heart rate and systolic and diastolic blood pressures were recorded continuously for 1 minute before, during, and 12 minutes after the stressor. Emotional state was measured periodically by questionnaires.

All hemodynamic variables were increased by the Stroop test. There was a pattern of blunted response to the Stroop test after cardiac transplantation, particularly in comparison with bypass patients, and slower recovery in comparison with both control groups. Emotional stress responses were similar in each group.

This pattern cannot be attributed to the experience of major heart surgery or to cardiac disease. Nor can it be explained by differences in central processing of stress. Correspondingly the changed hemodynamic response to the Stroop test after cardiac transplantation evidently does not affect patients' emotional responses. The hemodynamic findings are consistent with an increased reliance on hormonal rather than neuronal hemodynamic regulation after cardiac transplantation.