Spontaneous baroreflex sensitivity after coronary artery bypass graft surgery as a function of gender and age

The effects of coronary artery bypass graft (CABG) surgery on spontaneous baroreflex (SBR) sensitivity and heart rate variability were examined in 11 women and 23 men preoperatively and 5 days postoperatively. Electrocardiograph RR interval and beat-by-beat arterial blood pressure data were collected continuously for 20 min in the supine and standing postures. Coarse graining spectral analysis was performed on the heart rate variability data. Spontaneous baroreflex sensitivity declined after surgery with a differential influence of gender. Men showed a decrease in SBR slope following surgery, with a greater decrease in the standing posture; the parasympathetic (PNS) indicator was lower postoperatively and in the standing posture; the reduction in low-frequency (LF) power was greater for the younger men. In women, the PNS indicator was lower in the standing posture. Both men and women showed a decrease in high-frequency power following CABG surgery, which decreased the sensitivity of the short-term cardiac control mechanisms that modulate heart rate, with the greater effects occurring in men. The reduction in SBR sensitivity indicates that the ability of the cardiovascular system to respond rapidly to changing stimuli was compromised. The decline in the PNS indicator implies that patients were vulnerable to the risks of myocardial ischemia, sympathetically mediated cardiac dysrhythmias, and sudden cardiac death.Key words: spectral analysis, spontaneous baroreflex sensitivity, CABG surgery, gender, age, posture.

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Heart rate variability following coronary artery bypass graft surgery as a function of recovery time, posture, and exercise

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y04-076 ◽

2004 ◽

Vol 82 (7) ◽

pp. 457-464 ◽

Cited By ~ 13

Author(s):

C Ann Brown ◽

Larry A Wolfe ◽

Sylvia Hains ◽

Glorianne Ropchan ◽

Joel Parlow

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Baroreflex Sensitivity ◽

Artery Bypass ◽

Bypass Graft ◽

Interval Data ◽

Artery Bypass Graft ◽

Low Intensity ◽

Spontaneous Baroreflex ◽

Low Intensity Exercise

This study examined the claim made by Niemela et al. (1992) that the decline in heart rate variability after coronary artery bypass graft surgery is irreversible. We tested six women and 16 men six and 12 weeks postoperative in three postures: in the supine position, in the standing position, and during low-intensity steady-state exercise. Beat-by-beat arterial blood pressure and electrocardiographic R–R interval data were collected continuously for 10 min in each condition. R–R interval data were analyzed with spectral analysis; baroreflex data were analyzed using the sequence method. Our results show that the indices of parasympathetic modulation improved over time, as seen by an | increased spontaneous baroreflex sensitivity and parasympathetic indicator, that both indices were affected by posture, and that spontaneous baroreflex sensitivity was also affected by low-intensity exercise. The effects of posture are consistent with attenuated responses of healthy older subjects to orthostatic stress. Similarly, the effects of low-intensity exercise are consistent with findings in healthy subjects. We found that spontaneous baroreflex sensitivity declined during exercise, whereas, in healthy subjects, this is maintained during low-intensity steady-state exercise. Our results of significant functional recovery between six and 12 weeks postoperative suggest that at least some of the autonomic dysfunction following surgery is temporary. Previously, no such duration of study has lasted longer than four or six weeks following cardiac surgery, which may not have been long enough to show significant functional restoration in heart rate variability.Key words: heart rate variability, spontaneous baroreflex sensitivity, CABG surgery, posture, exercise.

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Influence of D,L-Sotalol on Baroreflex Sensitivity Response to Posture Following Coronary Artery Bypass Graft Surgery in Men and Women

Biological Research For Nursing ◽

10.1177/1099800413481241 ◽

2013 ◽

Vol 16 (2) ◽

pp. 182-190

Author(s):

C. Ann Brown ◽

Nicole Chenier-Hogan ◽

Sylvia M. J. Hains ◽

Joel L. Parlow

Keyword(s):

Coronary Artery ◽

Coronary Artery Bypass Graft ◽

Coronary Artery Bypass ◽

Baroreflex Sensitivity ◽

Artery Bypass ◽

Bypass Graft ◽

Artery Bypass Graft ◽

Standing Posture ◽

Cabg Surgery ◽

Supine Posture

Low baroreflex sensitivity (BRS) following coronary artery bypass graft (CABG) surgery increases the risk of sympathetically mediated cardiac arrhythmias. To reduce this risk, d,l-sotalol, a nonselective β-adrenergic receptor antagonist (Class II) and an antiarrhythmic (Class III), is prescribed postoperatively. However, its effect on BRS has not been reported. The purpose of this study was to characterize the influence of d,l-sotalol on BRS measures in supine and standing postures 4 days following CABG surgery. BRS was measured in 27 men and 10 women receiving d,l-sotalol and compared with archival data for 21 men and 10 women obtained prior to the routine administration of d,l-sotalol. In the latter (control) group, 61% had BRS of less than 3 ms/mmHg in the supine posture and 74% in the standing posture compared to 42% with less than 3 ms/mmHg in the supine posture and 65% in the standing posture in the d,l-sotalol group. Men in the d,l-sotalol group showed higher R-R interval and BRS in both supine and standing postures compared with controls. Women in the d,l-sotalol group had higher R-R interval in the supine posture. The higher BRS in men not only reduces the risk of arrhythmias after CABG surgery but may also allow a more rapid circulatory response to the standing posture, thereby decreasing the risk of syncope.

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Heart Rate Variability Response to Standing in Men and Women Receiving d,l-Sotalol Following Coronary Artery Bypass Graft Surgery

Biological Research For Nursing ◽

10.1177/1099800410396208 ◽

2011 ◽

Vol 14 (1) ◽

pp. 38-47 ◽

Cited By ~ 4

Author(s):

N. Chenier-Hogan ◽

C. A. Brown ◽

S. M. J. Hains ◽

J. L. Parlow

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Nervous System ◽

Coronary Artery ◽

Coronary Artery Bypass Graft ◽

Artery Bypass ◽

Bypass Graft ◽

Artery Bypass Graft ◽

Men And Women ◽

Cabg Surgery

Heart rate variability (HRV), a quantitative marker of autonomic control of heart rate (HR), declines in men and women following coronary artery bypass graft (CABG) surgery. Although d,l-sotalol is prescribed following CABG surgery primarily for its antiarrhythmic effect, its effects on HRV have not been reported; the β-adrenergic antagonist effect of d,l-sotalol may attenuate sympathetically mediated HR and blood pressure (BP) responses to standing, resulting in postural hypotension. In this study, the HRV response to standing 4 days following CABG surgery in men and women prescribed d,l-sotalol was measured to examine the influence of d,l-sotalol on previously reported HRV responses, taking age and gender into consideration. Participants included 28 men and 10 women who completed testing in supine and standing postures; all had received low-dose d,l-sotalol daily since the first postoperative day. Data included continuous electrocardiograph recording of R-R interval for 10 min in each posture. Participants showed significant effects of standing on the autonomic modulation of HR, as seen by a decrease in parasympathetic indices and R-R interval and an increase in BP. In men, standing decreased parasympathetic modulation and increased the sympathetic nervous system indicator, but previously reported age effects were not seen. In women, standing decreased low frequency power and R-R interval and increased BP, with older women having a smaller increase in BP, suggesting an attenuated response. The differential autonomic nervous system modulation of HR as a function of gender and age after CABG surgery may be attenuated by d,l-sotalol.

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