Circadian pattern of blood pressure and heart rate in the longer term after heart transplantation.

A loss of the circadian rhythm pattern of the blood pressure (BP) and heart rate (HR) as well as the development of hypertension has been found after heart transplantation (Htx). To determine whether a reappearance of this rhythm occurs in the long term after Htx, we used 24-h ambulatory monitoring to study 27 patients 1.7+/-1.6 years (range of 10 days to 4.3 years) after Htx. Patients were divided into two groups: group I (short term), Htx less than 6 months (n = 7); and group 2 (long term), Htx more than 6 months previously (n = 20). Group 2 had significantly higher diastolic BP as well as a greater fall in systolic BP during the night (-0.4+/-8.0 vs. 9.0+/-7.2 mm Hg, p < 0.01). There was also a higher day HR found in group 2 (73.2+/-14.5 vs. 96.8+/-12.5 beats/min, p < 0.001) as well as a larger fall in night HR in group 2 (4.2+/-5.5 vs. 11.9+/-4.9 beats/min, p < 0.005). The return of the circadian rhythm pattern in the longer term after Htx may result from partial reinervation of the heart, although other neurohumoral factors or concomitant medication (lower steroid dosages) may play a role.