Respiratory systolic pressure variability during atrial fibrillation and sinus rhythm

Previous studies have found that respiratory variations of ventricular resp onse in atrial fibrillation are infrequent and inconsistent. This asynchron y between heart rate and respiration may characterize the physiological mec hanisms coupling heart rate and systolic blood pressure oscillations in the respiratory band. The aim of this study was to evaluate whether synchronou s variations in systolic blood pressure and respiration depend on a simulta neous change in heart rate, Univariate and bivariate spectral analyses were made of the R-R interval, systolic blood pressure, and respiratory signals during controlled respiration (16 breaths/min) in 24 patients with atrial fibrillation before and after efficacious electrical cardioversion and in 2 4 age- and sex-matched control subjects. During atrial fibrillation, the sp ectral coherence between respiration and heart rate was low (0.18+/-0.03), but there was a high level of coherence between respiration and systolic bl ood pressure (0.67+/-0.05). After cardioversion, the coherence between resp iration and heart rate increased to 0.86+/-0.04, whereas the geometric mean values of the concomitant respiratory systolic blood pressure oscillations decreased by 72% (from 21.1 to 5.9 mm Hg-2, P<0.001), which was similar to that observed in the control group (5.7 mm Hg-2). These results confirm th e inconsistent effect of respiration on heart rate response during atrial f ibrillation and demonstrate that respiratory sinus arrhythmia is not a prer equisite for systolic blood pressure oscillations bur may play an antioscil latory role in respiratory systolic blood pressure variability, which is pr obably mediated by arterial baroreflex mechanisms.