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Influence of testing posture on autonomic cardiorespiratory reflexes
97 the cerebral microvessels in AD patients might possess abnormal metabolic properties in cholinergic or adrenergic system, introducing disordered autoregulation of cerebral circulation.
108 Pancreas and Kidney Transplantation: Effect on Autonomic Neuropathy M.G. Natali Sora 1, M. Ciani l, S. Martinenghi 2, A. Secchi 2, G. Comi I and N. Canal
1Clinica Neurologica e Clinica Medica and elstituto Scientifico Ospedale San Raffaele, Universit3 degli Studi di Milano, via Olgettina 60, 20132, Milan, Italy Autonomic nervous system dysfunction is a common complication of long-standing diabetes mellitus, although clinical symptoms are rarely present. While most parts of autonomic nervous system may be affected, it is the cardiovascular damage that can result in life-threatening consequences. Attempts to reverse the progressive course of diabetic autonomic neuropathy with pharmacological intervention have been mostly disappointing. Long-term normoglycaemia can be established in diabetic subjects after pancreatic transplantation; therefore we have evaluated the effect of successful pancreatic and kidney transplantation on autonomic neuropathy in 22 type 1 (insulin-dependent) diabetic subjects. Cardiovascular reflex tests were performed before, 1 year (22 pts) and 2 years (13 pts) after transplantation. A control group of 10 type 1 diabetic patients in waiting list for pancreas and kidney transplantation was examined at the same time periods. Advanced autonomic neuropathy was present in both groups and no significant changes in test results could be found at post-transplant evaluation at 1 year in both groups and also at two years in the transplanted group.
109 Influence of Testing Posture on Autonomic Cardiorespiratory Reflexes X. Navarro and W.R. Kennedy
Universitat A utonoma de Barcelona, Bellaterra, Spain, and University of Minnesota, Minneapolis, USA This study was designed to assess the effect of testing posture, either sitting or supine, on the results and diagnostic yield of cardiorespiratory reflexes. The subjects of the study were 25 normal controls and 128 diabetic patients. The heart rate changes during deep breathing at 6/min (AR6) and during a Valsalva maneuver (VR) were measured from the electrocardiographic signal and
tachometry. In control subjects, AR6 averaged 24.99 (SD 6.69) when sitting and 21.33 (5.01) when supine (P < 0.01); VR averaged 1.90 (0.39) and 1.83 (0.33) (P>0.2), respectively. In diabetic patients, mean values for AR6 were 6.12 (7.06) and 5.28 (6.64), and for VR 1.23 (0.25) and 1.28 (0.28) in sitting and supine postures, respectively. According to our previously defined normal limits, AR6 was below normal in 109 patients when tested sitting and 113 in supine, and VR was abnormal in 103 and 95, respectively. These results indicate that subject posture is an important determinant of cardiorespiratory reflex testing, that should be standardized to allow comparison of individual results during time and between studies from different laboratories.
110 Autonomic Nervous System Modulates Atrio-ventricular Conduction Time in Humans: a Comparison with Heart Rate Variability G. Nollo l, M. Del Greco 2, F. Ravelli l, G. Speranza I and M. Disertori 2
1Department of Medical Biophysics, IRST, 38050 Povo, Trento, and 20spedale Civile, 38068 Rovereto, Italy To investigate the influences of the autonomic nervous system (ANS) on atrio-ventricular conduction in humans, the spontaneous fluctuations of the atrio-ventricular conduction time (AR interval) were studied and compared to those of the cycle length (AA interval). Ten minutes of surface ECG and oesophageal electrogram from 10 healthy subjects in supine position and during 60 ° tilt were recorded. The A-wave and R-wave fiducial points were automatically measured respectively on the oesophageal and on the surface ECG (sampling rate: 1 kHz). The AA and AR interval series have been characterized by statistical parameters both in time and frequency domains. The mean values of AA and AR intervals before tilt were 932.2 and 134.6 ms. During tilt a significant (P<0.0001) decrease in the mean cycle length ( < A A > = 717.9 ms), but no significant reduction of the AR mean values ( < A R > = 133.6 ms) was documented. A A spectra showed a power density distribution concentrated in 2 main bands: low frequency: (LF) 0.040.12 Hz, high frequency: (HF) 0.15-0.4 Hz. The AR spectra were similarly characterized by LF and H F bands. Whereas the AA PSD shows an LF power increase (from 0.34 to 0.56 n.u., P < 0.05) and H F power decrease during tilt (from 0.24 to 0.09 n.u., P<0.05), the AR PSD shows a decrease of the power contents in both LF and H F bands (from 0.48 to 0.30, P<0.05). The study of AR interval variability seems to provide useful parameters to evaluate the influence of the ANS on the AV con-
108 Pancreas and Kidney Transplantation: Effect on Autonomic Neuropathy M.G. Natali Sora 1, M. Ciani l, S. Martinenghi 2, A. Secchi 2, G. Comi I and N. Canal
1Clinica Neurologica e Clinica Medica and elstituto Scientifico Ospedale San Raffaele, Universit3 degli Studi di Milano, via Olgettina 60, 20132, Milan, Italy Autonomic nervous system dysfunction is a common complication of long-standing diabetes mellitus, although clinical symptoms are rarely present. While most parts of autonomic nervous system may be affected, it is the cardiovascular damage that can result in life-threatening consequences. Attempts to reverse the progressive course of diabetic autonomic neuropathy with pharmacological intervention have been mostly disappointing. Long-term normoglycaemia can be established in diabetic subjects after pancreatic transplantation; therefore we have evaluated the effect of successful pancreatic and kidney transplantation on autonomic neuropathy in 22 type 1 (insulin-dependent) diabetic subjects. Cardiovascular reflex tests were performed before, 1 year (22 pts) and 2 years (13 pts) after transplantation. A control group of 10 type 1 diabetic patients in waiting list for pancreas and kidney transplantation was examined at the same time periods. Advanced autonomic neuropathy was present in both groups and no significant changes in test results could be found at post-transplant evaluation at 1 year in both groups and also at two years in the transplanted group.
109 Influence of Testing Posture on Autonomic Cardiorespiratory Reflexes X. Navarro and W.R. Kennedy
Universitat A utonoma de Barcelona, Bellaterra, Spain, and University of Minnesota, Minneapolis, USA This study was designed to assess the effect of testing posture, either sitting or supine, on the results and diagnostic yield of cardiorespiratory reflexes. The subjects of the study were 25 normal controls and 128 diabetic patients. The heart rate changes during deep breathing at 6/min (AR6) and during a Valsalva maneuver (VR) were measured from the electrocardiographic signal and
tachometry. In control subjects, AR6 averaged 24.99 (SD 6.69) when sitting and 21.33 (5.01) when supine (P < 0.01); VR averaged 1.90 (0.39) and 1.83 (0.33) (P>0.2), respectively. In diabetic patients, mean values for AR6 were 6.12 (7.06) and 5.28 (6.64), and for VR 1.23 (0.25) and 1.28 (0.28) in sitting and supine postures, respectively. According to our previously defined normal limits, AR6 was below normal in 109 patients when tested sitting and 113 in supine, and VR was abnormal in 103 and 95, respectively. These results indicate that subject posture is an important determinant of cardiorespiratory reflex testing, that should be standardized to allow comparison of individual results during time and between studies from different laboratories.
110 Autonomic Nervous System Modulates Atrio-ventricular Conduction Time in Humans: a Comparison with Heart Rate Variability G. Nollo l, M. Del Greco 2, F. Ravelli l, G. Speranza I and M. Disertori 2
1Department of Medical Biophysics, IRST, 38050 Povo, Trento, and 20spedale Civile, 38068 Rovereto, Italy To investigate the influences of the autonomic nervous system (ANS) on atrio-ventricular conduction in humans, the spontaneous fluctuations of the atrio-ventricular conduction time (AR interval) were studied and compared to those of the cycle length (AA interval). Ten minutes of surface ECG and oesophageal electrogram from 10 healthy subjects in supine position and during 60 ° tilt were recorded. The A-wave and R-wave fiducial points were automatically measured respectively on the oesophageal and on the surface ECG (sampling rate: 1 kHz). The AA and AR interval series have been characterized by statistical parameters both in time and frequency domains. The mean values of AA and AR intervals before tilt were 932.2 and 134.6 ms. During tilt a significant (P<0.0001) decrease in the mean cycle length ( < A A > = 717.9 ms), but no significant reduction of the AR mean values ( < A R > = 133.6 ms) was documented. A A spectra showed a power density distribution concentrated in 2 main bands: low frequency: (LF) 0.040.12 Hz, high frequency: (HF) 0.15-0.4 Hz. The AR spectra were similarly characterized by LF and H F bands. Whereas the AA PSD shows an LF power increase (from 0.34 to 0.56 n.u., P < 0.05) and H F power decrease during tilt (from 0.24 to 0.09 n.u., P<0.05), the AR PSD shows a decrease of the power contents in both LF and H F bands (from 0.48 to 0.30, P<0.05). The study of AR interval variability seems to provide useful parameters to evaluate the influence of the ANS on the AV con-