[Disorders of autonomic heart rate regulation in patients with brain stem lesions]

The present study investigates the frequency of alterations of autonomic cardiac innervation in patients with brain stem lesions by testing cardio-vascular reflexes tests. In the neurological ICU, we tested 22 patients aged 19 to 78 years (mean age 54 +/- 17 years) suffering from ischemic brain stem lesions. The variability of heart rate was at first evaluated at rest. Mean heart rate, coefficient of variation (VK) and RMSSD (root mean square of successive differences) were calculated. In addition, a spectral analysis of the heart frequency was computed by a fast fourier transformation and the spectral powers in the frequency bands 0.02-0.09 Hz, 0.09-0.15 Hz and 0.20-0.30 Hz, respectively were determined. An atropine test was then carried out. 5 minutes after the beginning of injection of atropine sulfate, further rate and spectral analyses were again computed. The VK was pathologically diminished in 59% of the patients, the RMSSD in 55% and both, VK and RMSSD, in 45%. In 32% of the patients VK and RMSSD were within normal range. Spectral power was diminished in all three frequency bands in 4 out of 22 patients with pathological heart rate variability. Most abnormal results in spectral analysis could be obtained in the frequency band 0.09-0.15 Hz (73%), followed by the frequency band 0.20-0.30 Hz (45%) and the 0.02-0.09 Hz frequency band (32%). There were significant correlations between the heart rate variability; the spectral power in the 0.09-0.15 Hz and 0.20-0.30 Hz frequency bands (p < 0.05; Spearman). 88% of the patients with abnormal results at rest had diminished heart rate responses to atropine.(ABSTRACT TRUNCATED AT 250 WORDS)