Altered heart rate variability but preserved relationships with sleep stages in a patient with primary aldosteronism

Objective: In a previous study, we found oscillations in the autonomic nerv ous system activity - as estimated by spectral analysis of R-R intervals - strongly linked to the non-rapid-eye movement (NREM) - REM sleep cycles, wi th low sympathetic activity during NREM sleep and predominant sympathetic a ctivity during REM sleep. In the present study we established the 5-min nig httime profiles in various measures of heart rate variability (HRV) in one patient with primary aldosteronism before and after successful surgery of C onn adenoma. Methods: One patient (female, 36 years old) with primary aldosteronism unde rwent two experimental nights a few weeks before and after surgery by coeli oscopy in which sleep and cardiac recordings were made. Power spectral anal ysis was performed on ectopic-free R-R intervals with a fast Fourier transf orm. We calculated also the standard deviation of normal R-R intervals (SDN N) and the root mean square difference among successive R-R intervals (RMSS D). Results: While removal of adenoma resulted in a rapid complete normalizatio n of blood pressure and classical signs and biological symptoms of aldoster one hypersecretion, HRV profile did not changed a few weeks after surgery. The overnight SDNN was low although not abnormal at 38 and 33 ms before and after surgery respectively vs 58 +/- 15 ms (33 to 83) in normal female con trols. RMSSD was low although not abnormal at 33 and 31 ms before and after surgery respectively vs 60 +/- 20 ms (20 to 105). The total spectrum power was low although not abnormal at 2.3 and 1.8 ms' before and after surgery, respectively vs 3.2 +/- 1.1 ms(2) (1.4 to 4.9). One out of the 8 controls had comparable or lower SDNN (33 ms), RMSSD (20 ms) and total power (1.4 ms (2)) values. While LF/HF ratio was comparable, the VLF (0.003-0.04 Hz) and LF (0.04-0.15 Hz) relative power were decreased and increased respectively in the patient compared in controls. Despite this reduced HRV, the normal t emporal relationship of spectral parameters with specific sleep stages was preserved. Conclusion: Altered HRV with normal temporal relationships with specific sl eep stages was observed in a patient with primary hyperaldosteronism. This HRV profile did not changed 20 weeks after successful surgery i.e. complete remission of classical signs and symptoms of aldosterone hypersecretion.