Respiratory Systolic Pressure Variability During Atrial Fibrillation and Sinus Rhythm

Abstract

Abstract-Previous studies have found that respiratory variations of ventricular response in atrial fibrillation are infrequent and inconsistent. This asynchrony between heart rate and respiration may characterize the physiological mechanisms coupling heart rate and systolic blood pressure oscillations in the respiratory band. The aim of this study was to evaluate whether synchronous variations in systolic blood pressure and respiration depend on a simultaneous 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 24 age-and sex-matched control subjects. During atrial fibrillation, the spectral coherence between respiration and heart rate was low (0.18Ϯ0.03), but there was a high level of coherence between respiration and systolic blood pressure (0.67Ϯ0.05). After cardioversion, the coherence between respiration and heart rate increased to 0.86Ϯ0.04, 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 , PϽ0.001), which was similar to that observed in the control group (5.7 mm Hg 2 ). These results confirm the inconsistent effect of respiration on heart rate response during atrial fibrillation and demonstrate that respiratory sinus arrhythmia is not a prerequisite for systolic blood pressure oscillations but may play an antioscillatory role in respiratory systolic blood pressure variability, which is probably mediated by arterial baroreflex mechanisms. (Hypertension. 1999;34:1060-1065.) Key Words: arrhythmia Ⅲ blood pressure Ⅲ heart rate T he clinical hallmark of atrial fibrillation (AF) is an irregular ventricular rhythm. Few studies have investigated the respiratory oscillations of ventricular rhythm during AF, 1-3 and only 2 4,5 have made use of spectral analysis. These last 2 studies reported the presence of respiratory arrhythmia during AF in a small percentage of patients, but none measured respiration as a factor of analysis.The mechanisms underlying the origin of respiratory sinus arrhythmia (RSA) are still debated, but 2 main and not mutually exclusive theories have been put forward: One considers it to be the effect of cycling respiratory stimulation on arterial baroreceptors (the "peripheral" theory), and the other emphasizes the direct role of central respiratory drive (the "central" theory). Bivariate spectral analyses may quantify the relations between the heart period (R-R interval) and systolic blood pressure (SBP) but do not build causality between 2 signals: The spontaneous relation between the R-R interval and SBP fluctuations is a closed loop, and crossspectral analysis is unable to separate the mechanical R-R-SBP feedforward by baroreflex feedback from SBP to R-R. 6 A number of methods 7-11 and models 12-15 for exploring the fundamental relations between R-R and SBP o...

Cardiorespiratory interactions in patients with atrial flutter

“…This clear evidence distinguishes atrial flutter from atrial fibrillation, where the irregularity of the rhythm prevails over respiratory patterning and even the presence of respiratory arrhythmia is a matter of debate (10,20,39,46,51). In atrial flutter, the simple reentrant mechanism underlying atrial activation determines a more regular rhythm, which makes the respiratory modulation apparent.…”

“…Nevertheless, frequencydomain techniques have been applied to a less extent in the characterization of cardiovascular oscillations during atrial arrhythmias (50,54,59). Spectral and cross-spectral analyses have been applied to individuate the presence of a respiratory modulation of heart rate and blood pressure in atrial fibrillation (23,46), whereas spectral analysis has been used to characterize the overall variability of atrial flutter cycle length (50,59). Focusing on the respiratory modulation of atrial flutter rhythms, in the present study we applied cross-spectral analysis to both atrial and ventricular interval series to test effectively the presence of coupling between atrial/ventricular series and respiration and to characterize the phase relation of the interaction.…”

“…Several studies have investigated the presence of cardiorespiratory interactions during atrial fibrillation, focusing mostly on the respiratory modulation of ventricular rate. Data indicate that during normal breathing, the irregularity of ventricular intervals prevails over respiratory patterning, which is an infrequent finding and, when observed, exerts inconsistent effects on ventricular rhythm (10,20,39,46,51). More consistent respiratory effects on heart rate have been observed during Cheney-Stokes respiration and apnea (19,32,63), where heart rate has been shown to oscillate in synchrony with the slow breathing patterns.…”

On the reliability of frequency components in systolic arterial pressure in patients with atrial fibrillation

“…As a consequence of the highly irregular heart rate, the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility. Only a few studies [4,14,15] have evaluated whether rhythmical components could be identified in short-term heart rate and systolic arterial pressure (SAP) variability during AF.…”

“…A respiratory-related HF component of systolic blood pressure variability has been observed during AF even in absence of a respiratory sinus arrhythmia of the RR series [14]. However, there is lack of information on the possible existence of LF component.…”