Blood pressure pattern in the recovery period after coronary artery bypass grafting.

Abstract

BACKGROUND: Data on ambulatory blood pressure profiles after coronary artery bypass grafting (CABG) are largely lacking in the literature. OBJECTIVE: To examine the ambulatory blood pressure profile and its short- and long-term variability (daytime, night-time and 24 h) 1, 6 and 14 weeks after CABG in 15 patients (14 men, one woman) who remained uncomplicated postoperatively and during the 14 weeks' follow-up. Therapy remained unchanged over the study period. METHODS: Short-term blood pressure and heart rate variability were assessed by power spectral analysis of a sample length of 256 beats of these parameters obtained with subjects supine and having stood for 30 min, using the Finapres device 1, 6 and 14 weeks after CABG. The low-frequency (0.04-0.15 Hz): high-frequency (0.15-0.40 Hz) ratio of the R-R interval variability was considered a study parameter for the autonomic balance. RESULTS: During the rehabilitation period office and mean ambulatory blood pressure parameters were within the normotensive range. There was a progressive increase in 24 h and daytime systolic and diastolic blood pressures from 1 (121+/- 11/72+/-9 and 124+/-11/74+/-9 mmHg, respectively) to 14 weeks (129+/- 11/79+/-10 and 134+/-11/82+/- 11 mmHg, respectively) after CABG. The nocturnal blood pressure dip was restored progressively but incompletely 14 weeks after CABG. In parallel there was a progressive but also incomplete restoration of the sympathicovagal balance. CONCLUSION: Our results indicate an incomplete recovery of the autonomic nervous system and 24 h blood pressure variation 14 weeks after CABG. Further studies are required to examine whether incomplete restoration of the nocturnal blood pressure dip and sympathicovagal balance have independent prognostic implications for the CABG patient.