RESPIRATORY-RELATED BLOOD-PRESSURE VARIABILITY IN PATIENTS AFTER HEART-TRANSPLANTATION

Our objective was to study whether the variations of blood pressure sy nchronous with respiration depend on the simultaneous changes of heart rate. Power spectral analysis of the heart period or R-R interval, bl ood pressure, and respiratory activity was performed by fast Fourier t ransform during 30 min of supine rest in 12 patients between 16 and 23 days after orthotopic heart transplantation and in 12 age- and sex-ma tched normal control subjects. The components of the variations of the R-R interval and blood pressure associated with respiration [high-fre quency (HF) components] were derived from the power spectra. The HF co mponent of the power spectrum of the R-R interval was almost absent in the transplanted patients compared with the control subjects (2.9 vs. 104 ms(2); P < 0.001), whereas the HF component of the power spectrum of blood pressure was not significantly different between the two gro ups (1.72 vs. 1.65 mmHg(2) for systolic and 0.35 vs. 0.60 mmHg(2) for diastolic blood pressure). Respiratory variations of both systolic and diastolic blood pressure in humans can depend only slightly on the re spiratory heart rate variations.