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At least 289 records · Page 16Linked to original sources
PubMed1994

Heart rate power spectrum analysis of autonomic dysfunction in adolescents with anorexia nervosa.

We studied autonomic modulation of heart rate in 8 females with anorexia nervosa (AN) using power spectral analysis (PSA) of heart rate variability in the supine and standing positions at baseline and after 2 weeks of intensive nutritional rehabilitation, and compared findings with healthy female control subjects. The results indicate that there is a decrease in sympathetic modulation of heart rate, evident by a deficit of low frequency (0.01-0.15 Hz) heart rate power in the supine position in AN compared with control subjects. In addition, parasympathetic modulation of heart rate failed to decrease with standing. A trend toward improvement in autonomic control of heart rate in adolescents with AN occurs in the supine position relatively early in weight rehabilitation. PSA is a sensitive, quantitative, and noninvasive means of determining autonomic control of heart rate and could be a useful tool in monitoring the health of patients with AN.

Adolescent↗
PubMed1999

Early autonomic dysfunction in patients with diabetes mellitus assessed by spectral analysis of heart rate and blood pressure variability.

Patients with diabetes mellitus (DM) often have alterations of the autonomic nervous system (ANS), even early in their disease course. Previous research has not evaluated whether these changes may have consequences on adaptation mechanisms in DM, e.g. to mental stress. We therefore evaluated whether patients with DM who already had early alterations of the ANS reacted with an abnormal regulatory pattern to mental stress. We used the spectral analysis technique, known to be valuable and reliable in the investigation of disturbances of the ANS. We investigated 34 patients with DM without clinical evidence of ANS dysfunction (e.g. orthostatic hypotension) and 44 normal control subjects (NC group). No patients on medication known to alter ANS responses were accepted. The investigation consisted of a resting state evaluation and a mental stress task (BonnDet). In basal values, only the 21 patients with type 2 DM were different in respect to body mass index and systolic blood pressure. In the study parameters we found significantly lower values in resting and mental stress spectral power of mid-frequency band (known to represent predominantly sympathetic influences) and of high-frequency and respiration bands (known to represent parasympathetic influences) in patients with DM (types 1 and 2) compared with NC group (5.3 +/- 1.2 ms2 vs. 6.1 +/- 1.3 ms2, and 5.5 +/- 1.6 ms2 vs. 6.2 +/- 1.5 ms2, and 4.6 +/- 1.7 ms2 vs. 6.2 +/- 1.5 ms2, for resting values respectively; 4.7 +/- 1.4 ms2 vs. 5.9 +/- 1.2 ms2, and 4.6 +/- 1.9 ms2 vs. 5.6 +/- 1.7 ms2, and 3.7 +/- 2.1 ms2 vs. 5.6 +/- 1.7 ms2, for stress values respectively; M/F ratio 6/26 vs. 30/14). These differences remained significant even when controlled for age, sex, and body weight. However, patients with DM type 2 (and significantly higher body weight) showed only significant values in mental stress modulus values. There were no specific group effects in the patients with DM in adaptation mechanisms to mental stress compared with the NC group. These findings demonstrate that power spectral examinations at rest are sufficiently reliable to diagnose early alterations in ANS in patients with DM. The spectral analysis technique is sensitive and reliable in investigation of ANS in patients with DM without clinically symptomatic autonomic dysfunction.

Adult↗
PubMed1986

Signs of cardiac autonomic dysfunction during sleep in patients with Alzheimer's disease.

Autonomic nervous system (ANS) failure may be an important complication in some neurological diseases. Conventional tests for the assessment of ANS functions during wakefulness cannot be used for many patients with dementia of the Alzheimer's type (DA) because of their poor cooperation. In 6 of 16 patients with presenile DAT we found signs of sympathetic cardiac dysfunction during sleep, measured as the decrease in body movement-related heart rate variation (Rbm). The study of Rbm during sleep seems to be a useful tool for ascertaining ANS function in DAT. The presence or absence of ANS dysfunction could be a more reliable criterion than age of onset for identifying subgroups of this disease.

Aged↗
PubMed1996

Autonomic dysfunction in hemodialysis patients with persistent hypotension.

To investigate autonomic mechanisms underlying persistent hypotension in long-term hemodialysis patients, high-frequency (HF, > 0.15 Hz) and low-frequency (LF, 0.04-0.15 Hz) components of heart rate variability and plasma noradrenaline were analyzed in 10 persistently hypotensive hemodialysis patients (group H), 11 normotensive patients (group N) and 10 healthy controls (group C). The HF amplitude, an index of cardiac parasympathetic activity, and LF-to-HF ratio, an index of sympathetic predominance, were in the order of groups C > N > H (p < 0.01). While the HF amplitude decreased with standing in all three groups (p < 0.05 for all), the LF-to-HF ratio increased only in groups N and C (p < 0.05 for both) but not in group H. Conversely, plasma noradrenaline level was in the order of groups C < N < H (p < 0.001). Furthermore, while the LF-to-HF ratio correlated positively with the plasma noradrenaline level in group C (r = 0.73, p < 0.01), it correlated negatively in group H (r = 0.69, p < 0.05). These results indicate that an impairment in both parasympathetic and sympathetic functions exists in hemodialysis patients with persistent hypotension, and that the apparent sympathetic dysfunction could result from a reduction in cardiovascular responsiveness to sympathetic stimulation.

Adrenergic Fibers↗
PubMed1993

Autonomic dysfunction in patients with chronic intestinal pseudo-obstruction.

We prospectively evaluated autonomic function in 50 patients with clinical and manometric features of a neuropathic form of chronic intestinal pseudo-obstruction (CIP). In 26 patients, there were underlying disease processes that may have affected extrinsic neural control to viscera: diabetes mellitus (n = 16), previous gastric surgery (n = 5), and other neurologic disorders (n = 5). Our aim was to characterize autonomic function in these patients, and those 24 with CIP unassociated with a known underlying neurologic disorder (idiopathic group). We assessed vagal function and sympathetic cholinergic and adrenergic function by means of standardized autonomic tests and quantitated postprandial antral pressure activity. We also measured postprandial levels of pancreatic polypeptide and neurotensin as indicators of vagal function and of the delivery of nutrients to the distal small bowel. Among the idiopathic group (n = 24), two had evidence of a generalized sympathetic neuropathy and five abdominal vagal dysfunction (one had both). Among diabetic patients, three had sympathetic adrenergic failure, six had orthostasis with normal plasma noradrenaline, ten had signs of generalized sympathetic neuropathy and eight had abdominal vagal dysfunction. Vagal dysfunction was identified in all three patients who underwent vagotomy as part of their previous gastric surgery. In the other neurologic syndromes, vagal function was abnormal in three of the five patients. Thus, autonomic and, particularly, vagal dysfunction are confirmed in a majority of patients with CIP associated with known diabetes or neurologic disorders; however, a previously unrecognized autonomic (chiefly vagal) neuropathy of undetermined cause has been identified in five of the 24 'idiopathic' CIP patients.

Autonomic Nervous System Diseases↗
PubMed2002

Hypertension in orthostatic hypotension and autonomic dysfunction.

Disabling orthostatic hypotension dominates the clinical picture of autonomic failure. Nonetheless, severe supine hypertension is observed in about 50% of patients. In patients with multiple system atrophy (Shy-Drager syndrome), supine hypertension is explained by residual sympathetic tone because it can be eliminated with the ganglionic blocker trimethaphan. The cause of hypertension in patients with pure autonomic failure is not known and its understanding may be relevant to essential hypertension. Supine hypertension complicates the treatment of these patients but can be managed by overnight administration of antihypertensive medications.

Humans↗
PubMed1989

Cardiac autonomic dysfunction in obese subjects.

1. The prevalence of cardiac autonomic alterations was evaluated in 23 obese subjects with body mass index 37.2 +/- 3.03 kg/m2 (mean +/- SD), compared with 78 controls with body mass index 22.5 +/- 2.6 kg/m2 (P less than 0.001). 2. Cardiac autonomic function was assessed by four standard tests (heart rate response to deep breathing and to the Valsalva manoeuvre, systolic blood pressure fall after standing and diastolic pressure rise during handgrip) and by the cross-correlation test, a new method of computerized analysis of respiratory sinus arrhythmia based on spectral analysis of electrocardiographic and respiratory signal. 3. Considering tests indicative of parasympathetic function, only the heart rate response to the deep breathing and the cross-correlation test were significantly lower in the obese than in the control group [deep breathing = 13.95 +/- 8.65 beats/min (mean +/- SD) vs 24.5 +/- 7.65, P less than 0.001; cross-correlation 4.28 +/- 0.74 units vs 5.14 +/- 0.63, P less than 0.001]. Deep breathing and/or cross-correlation were abnormal in 10 (43.5%) obese subjects (deep breathing: seven subjects, cross-correlation: eight subjects). No significant difference between groups was found for the response to the Valsalva manoeuvre: the Valsalva ratio was 1.69 +/- 0.45 in obese subjects and 1.88 +/- 0.33 in controls (P = NS). The Valsalva ratio was abnormal in three obese subjects. 4. No significant differences were found between groups for tests indicative of sympathetic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Relationship between autonomic dysfunction and BP variability in subjects with diabetes mellitus.

Autonomic vagal heart rate (HR) control, office BP and ambulatory BP were examined in 54 diabetic subjects, aged 63 +/- 6 years. Sixteen subjects were insulin-dependent. The HR response to deep breathing (the bradypnoea test) was used to evaluate the vagal HR control, and ambulatory BP was determined by the Spacelabs 5200 system (one determination every 15 minutes, for 24 hours). Twenty-seven subjects had normal office BP (SBP < or = 140 mmHg and DBP < or = 90 mmHg), seven had established hypertension (SBP > or = 160 mmHg and DBP > or = 95 mmHg) and 30 were borderline hypertensives. Over the total group, office systolic/diastolic BP (mean +/- SD) was 142 +/- 20/85 +/- 10 mmg. Systolic/diastolic ambulatory BP was 123 +/- 13/77 +/- 10 mmHg and ambulatory HR was 70 +/- 8 beats/min. Because of the small age range of our subjects, the HR score was not correlated with age (r = 0.19, NS). The HR score was not correlated with the levels of office and ambulatory pressures. In contrast, it was significantly correlated with the variability of ambulatory SBP, whether the variability was defined by the pressure standard deviation, or by the ratio SD/mean value (r = 0.40, P = 0.005 and r = 0.33, P < 0.017, respectively). We suggest that an impairment of the autonomic control in diabetics might induce an increase in variability of SBP. BP variability might play a role in the cardiovascular complications observed in diabetics.

Aged↗
PubMed1990

The relationship between locomotor disability, autonomic dysfunction, and the integrity of the striatal dopaminergic system in patients with multiple system atrophy, pure autonomic failure, and Parkinson's disease, studied with PET.

18F-dopa and S-11C-nomifensine (NMF) are positron emitting tracers whose caudate and putamen uptake reflects striatal dopamine storage capacity and the integrity of dopamine reuptake sites, respectively. Using these two tracers, the integrity of the presynaptic striatal dopaminergic system has been studied with positron emission tomography (PET) in 10 subjects with multiple system atrophy (MSA, Shy-Drager syndrome) who had an akinetic-rigid syndrome that was poorly responsive to L-dopa, autonomic failure, and cerebellar ataxia. PET findings for the 10 MSA patients were compared with those for 13 age-matched controls, 8 subjects with L-dopa responsive Parkinson's disease (PD), and 7 subjects with pure autonomic failure (PAF). Influx constants, Ki, reflecting specific 18F-dopa uptake into striatal tissue, were severely reduced in the putamen and caudate of the 10 MSA subjects (mean putamen Ki 0.005 min-1 MSA vs 0.013 min-1 controls; mean caudate Ki 0.007 min-1 MSA vs 0.013 min-1 controls). Reduction of putamen, but not caudate, 18F-dopa uptake correlated with severity and duration of locomotor disability. Eight patients with PD, and a similar degree and duration of locomotor disability to the patients with MSA, demonstrated equal impairment of mean putamen 18F-dopa uptake, but significant preservation of mean caudate function. The 7 PAF patients had normal mean levels of putamen and caudate 18F-dopa uptake, although 1 individual PAF patient had significantly impaired striatal function. The MSA and PD groups of subjects both showed significantly reduced levels of specific striatal S-11C-NMF binding, again caudate function being relatively preserved in PD. It is concluded that in both MSA and PD there is a parallel decline of striatal dopamine storage capacity and reuptake site integrity, probably reflecting a loss of nigrostriatal nerve terminals. Caudate function is relatively preserved in PD compared with MSA. The majority of PAF patients have an intact nigrostriatal dopaminergic system, suggesting that PAF is a condition distinct from PD and MSA in spite of some pathological similarities. PET is capable of detecting subclinical nigrostriatal involvement in PAF patients when this is present.

Adult↗