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PubMed2003

Influences of an anticholinergic antiparkinsonian drug, parkinsonism, and psychotic symptoms on cardiac autonomic function in schizophrenia.

The arguments against the use of anticholinergic antiparkinsonian drugs for neuroleptic-induced parkinsonism have been based, in part, on their autonomic side effects. Except for anecdotal case reports, there is little evidence that antiparkinsonian drugs are the main factor causing autonomic dysfunction in schizophrenic patients with parkinsonism. Therefore, in the current study, the separate influences of the anticholinergic antiparkinsonian drug (biperiden), parkinsonism, and psychotic symptoms on cardiac autonomic function were investigated in 48 patients with schizophrenia. Biperiden was discontinued in 33 patients with or without parkinsonism and commenced in 15 patients with parkinsonism. Their parkinsonism and psychotic symptoms were assessed using rating scales, and their cardiac autonomic functions were assessed using the mean R-R interval and 3 methods of analyzing heart rate variability both before and after the change in medication. Consequently, the cardiac autonomic function was not affected by biperiden or the change in parkinsonism. Cardiac vagal function decreased when psychotic symptoms were more pronounced, but cardiac sympathetic function did not show a significant change. Therefore, it appeared that psychotic symptoms played the predominant role in modifying the cardiac autonomic function, implying the existence of autonomic changes associated with cognitive processing and a possible relation between psychotic symptoms and autonomic symptoms in schizophrenia.

Adult↗
PubMed1997

Cardiac autonomic function and sensitivity to pain in postmenopausal women with angina and normal coronary arteries.

An increased sensitivity to painful stimuli and an abnormal cardiac autonomic function have previously been reported in patients with angina and angiographically normal coronary arteries, a syndrome that mainly affects postmenopausal women. In this study we compared both general sensitivity to pain, by evaluating time to forearm ischemic pain (FIP) provoked by sphygmomanometer cuff inflation, and cardiac autonomic function, by measuring heart rate variability (HRV), and QT and QT(c) intervals on 24-hour Holter recordings, in 25 postmenopausal women with angina and normal coronary arteries and in 22 healthy postmenopausal women. Compared with controls, patients had a reproducible strikingly lower time to FIP (149 +/- 121 vs 295 +/- 158 seconds, p <0.001), whereas there were no differences between the 2 groups in HRV variables and mean 24-hour QT and QT(c) intervals. HRV indexes, and QT and QT(c) intervals also showed similar circadian patterns. Thus, our data show that postmenopausal women with angina and normal coronary arteries have an enhanced sensitivity to systemic painful stimuli, but no detectable impairment in cardiac autonomic function compared with a well-matched control group of postmenopausal healthy women.

Angina Pectoris↗
PubMed1997

A new method of assessing cardiac autonomic function and its comparison with spectral analysis and coefficient of variation of R-R interval.

A new non-linear method of assessing cardiac autonomic function was examined in a pharmacological experiment in ten healthy volunteers. The R-R interval data obtained under a control condition and in autonomic blockade by atropine and by propranolol were analyzed by each of the new methods employing Lorenz plot, spectral analysis and the coefficient of variation. With our method we derived two measures, the cardiac vagal index and the cardiac sympathetic index, which indicate vagal and sympathetic function separately. These two indices were found to be more reliable than those obtained by the other two methods. We anticipate that the non-invasive assessment of short-term cardiac autonomic function will come to be performed more reliably and conveniently by this method.

Adult↗
PubMed1997

Cardiac autonomic function during sleep in several neuropsychiatric disorders.

Cardiac autonomic activity during sleep is only very slightly influenced by the emotional state of the patient and, unlike some of the traditional tests of autonomic function, may be studied in all patients. In an attempt to evaluate autonomic function in patients with different neuropsychiatric disorders, two different methods of quantifying the changes in sympathetic and parasympathetic cardiac control during sleep were used: (1) the ratios of consecutive R-wave (R-R) intervals before and after spontaneous body movements; (2) spectral analysis of R-R intervals. It was found that more than one third of patients with presenile Alzheimer's disease had defective cardiac sympathetic control. Untreated parkinsonian patients showed predominantly defective parasympathetic, and to a lesser extent sympathetic, function during sleep. In these patients, as well as in patients with multiple sclerosis, autonomic evaluation during sleep led to earlier detection of impairment than the traditional tests during wakefulness. Narcoleptic patients and patients with panic disorder showed normal autonomic function during sleep, but had altered control levels during the wakeful period before sleep. The findings in these narcoleptic patients were probably related to the impairment of their sleep-wake cycle. The sympathetic overactivity found in patients with panic disorder was probably a result of cognitive activity, as the nocturnal data excluded an intrinsic defect in autonomic regulation.

Alzheimer Disease↗
PubMed1995

Triazolam and melatonin effects on cardiac autonomic function during sleep.

After benzodiazepine (BDZ) administration, a decrease in cardiac vagal tone has been described during wakefulness, but data on cardiac autonomic function during sleep are lacking. Melatonin (MLT), reported to have hypnotic properties, caused an increase in vagal tone in animals. The aim of this study was to evaluate heart rate (HR) variability during sleep after a single bedtime dose of triazolam (TRI, 0.125 mg) and MLT (100 mg) in six healthy young subjects. We evaluated tonic (vagal activity) HR modifications in relation to sleep as well as phasic (sympathetic activity) HR modifications in relation to spontaneous body movements during rapid-eye-movement (REM) and non-REM (NREM) sleep. No significant change in sympathetic activity was observed after TRI and MLT in comparison with placebo, whereas TRI caused a significant decrease in vagal tone during sleep. Our nocturnal study seems to confirm previous diurnal findings about a decrease in vagal tone by BDZs.

Adult↗
PubMed2006

Effects of circumferential or segmental pulmonary vein ablation for paroxysmal atrial fibrillation on cardiac autonomic function.

BACKGROUND: Circumferential and segmental pulmonary vein ablations are two established treatment strategies for ablation of atrial fibrillation. Both techniques require the application of radiofrequency current at anatomical sites that are close to autonomic ganglia. However, the effects of current pulmonary vein ablation techniques on cardiac autonomic function are unknown. OBJECTIVE: The purpose of this study was to analyze the short- and long-term effects of circumferential and segmental pulmonary vein ablation on cardiac autonomic function. METHODS: One hundred patients with highly symptomatic atrial fibrillation were randomly assigned to undergo either circumferential or segmental pulmonary vein ablation. Holter recordings were recorded at baseline and at regular intervals for up to 1 year after ablation. Autonomic function was assessed by deceleration capacity and acceleration capacity of heart rate as well as by standard measures of heart rate variability. RESULTS: In the circumferential pulmonary vein ablation group, deceleration capacity and acceleration capacity decreased highly significantly from 5.7 +/- 2.1 ms and -8.0 +/- 1.9 ms at baseline to 3.3 +/- 1.8 ms and -5.5 +/- 2.3 ms directly after ablation, respectively (P<.00001). Impairment of deceleration capacity and acceleration capacity was present up to 1 year after ablation. In the segmental pulmonary vein ablation group, deceleration capacity and acceleration capacity decreased from 5.8 +/- 2.0 ms and -7.8 +/- 1.6 ms at baseline to 3.4 +/- 1.2 ms and -6.0 +/- 2.4 ms directly after ablation (P<.00001), respectively. However, deceleration capacity and acceleration capacity returned to baseline values within 1 month. CONCLUSIONS: Circumferential and segmental pulmonary vein ablations induce an immediate decrease of autonomic function. However, while this decrease is only transient with segmental pulmonary vein ablation, it persists with circumferential pulmonary vein ablation for at least 1 year.

Aged↗
PubMed2005

Maternal cardiac autonomic function and fetal heart rate in preeclamptic compared to normotensive pregnancies.

BACKGROUND: Preeclampsia during pregnancy increases a woman's risk of cardiovascular disease in two ways. Women who develop preeclampsia are at increased risk for the development of hypertension and cardiovascular disease later in life. As well, fetal adaptations (e.g., growth restriction) may lead to the development of cardiovascular risk factors (e.g., obesity, increased cholesterol) in the offspring. Although atypical maternal cardiac autonomic function has been reported in preeclampsia, to date, its effects on fetal cardiac function have not been determined. PURPOSE: To characterize the pattern of short-term maternal cardiac autonomic modulation and spontaneous fetal heart rate changes in preeclamptic compared to normotensive women and to determine the relationship between them. METHOD: Twenty-seven mother-fetal pairs (n = 9 preeclamptic, n = 18 normotensive) at 32 to 40 weeks gestation were tested on one occasion. Maternal autonomic modulation of heart rate was measured for 20 minutes using electrocardiographic and beat-by-beat arterial systolic blood pressure recordings. Simultaneously, spontaneous fetal heart rate was obtained using a cardiotachograph. Women's cardiac autonomic responses to orthostatic stress were obtained for five minutes in a standing position. RESULTS: Comparisons of maternal cardiac measures in the preeclamptic versus the normotensive group showed that the preeclamptic group had a decreased parasympathetic nervous system indicator and an increased sympathetic nervous system indicator with increasing gestation. In response to orthostatic stress, women in both groups showed a similar increase in arterial systolic blood pressure and a decrease in parasympathetic nervous system indicator and R-R interval when standing compared to lying. Fetuses in the normotensive compared to the preeclamptic group had more spontaneous fetal heart rate accelerations; the greater the decrease in the parasympathetic nervous system indicator from lying to standing, the greater the number of fetal heart rate accelerations. CONCLUSIONS: These findings serve to further our understanding of the cardiovascular pathophysiology of preeclampsia in both the mother and the fetus. Women who develop preeclampsia during pregnancy show atypical autonomic nervous system modulation of heart rate that is associated with a decrease in spontaneous fetal heart rate accelerations in late gestation. Implications for cardiovascular nursing practice include the monitoring of maternal cardiac autonomic function during pregnancy, especially during standing, as well as a need for continued surveillance of maternal cardiovascular function following pregnancy. The negative effect on fetal heart rate accelerations has implications for the interpretation of standardized obstetrical tests of fetal well-being.

Adult↗
PubMed2005

Subclinical effects of prenatal methylmercury exposure on cardiac autonomic function in Japanese children.

OBJECTIVES: The subclinical effects of prenatal exposure to methylmercury from fish consumption on the cardiac autonomic function were assessed in 136 Japanese 7-year-old children recruited for this study. METHODS: Samples of child's hair and dry umbilical cord preserved were collected, and hair mercury and cord tissue methylmercury concentrations were determined as current and prenatal exposure biomarkers, respectively. Cardiac autonomic indicators of parasympathetic and sympathetic activities were calculated from the electrocardiographic RR intervals measured. RESULTS: In the children, the cord tissue methylmercury (0.017-0.367, median 0.089 microg/g) was not significantly correlated with the hair mercury (0.43-6.32, median 1.66 microg/g). The cord tissue methylmercury was related negatively to parasympathetic components of cardiac autonomic indicators (P < 0.05) and positively to sympathovagal indices (P < 0.05), even after correction for possible confounders such as age and sex, although the hair mercury was not significantly correlated with any cardiac autonomic indicators. CONCLUSIONS: Despite the potential limitations involved in the retrospective study, these findings suggest that prenatal methylmercury exposure (median of estimated maternal hair mercury at parturition, 2.24 microg/g) may be associated with reduced parasympathetic activity and/or sympathovagal shift.

Animals↗
PubMed2006

Cold pressor test protocol to evaluate cardiac autonomic function.

The primary objective of this study was to develop a cold pressor test (CPT) protocol to evaluate cardiac autonomic function. Secondary objectives were to assess CPT protocol reliability and to examine gender differences in response to orthostatic stress and the CPT. Healthy, normotensive men and women (n = 12 per group) completed 2 trials on different days in the left lateral decubitus and standing postures and during a 6 min CPT (hand immersion while seated). Measurements included R-R interval, blood pressure, ventilatory responses, spontaneous baroreflex sensitivity, and heart rate variability indices. During the CPT, blood pressure and the sympathetic nervous system (SNS) indicator increased significantly and low-frequency power, high-frequency power (normalized for tidal volume), and the parasympathetic nervous system (PNS) indicator decreased significantly. Standing caused significant increases in the SNS indicator and decreases in the R-R interval in both genders. The PNS indicator was higher in women than in men in the left lateral decubitus posture. The 6 min hand-immersion CPT provoked cardiac sympathetic activation and parasympathetic withdrawal; however, it is best suited to studies with a repeated measures design, as analysis of reliability suggests that responses are highly variable between individuals. Performing the CPT in the left lateral decubitus position may prevent vasovagal responses.

Adult↗
PubMed1995

Cardiac autonomic function in obese patients.

OBJECTIVE: The aim of this work was to determine the presence and prevalence of alterations in cardiac autonomic function in obese, non-diabetic subjects. SUBJECTS: These were 121 obese people, 15 with glucose intolerance and none with diabetes, and a group of 40 healthy people. MEASUREMENTS: A series of five standardized tests was carried out, three of which were based mainly on parasympathetic control (heart rate response to Valsalva, deep breathing and lying-to-standing) and two on cardiovascular sympathetic function (blood pressure response to standing and to handgrip). RESULTS: The response to the deep breathing test correlated negatively with age, as it did in control subjects. At least one parasympathetic test, age-adjusted, was abnormal in 49 patients (40.5%). Five other patients had an abnormal handgrip test, and no patient had orthostatic hypotension. No correlation was found between the parasympathetic test results and sex or body mass index. Prevalence of cardiac autonomic dysfunction, considered to be present when at least one parasympathetic test was abnormal, did not differ according to a gynoid or android type of obesity. A significant negative correlation was found between heart rate response to deep breathing and fasting glycemia. CONCLUSION: It was concluded that cardiac autonomic dysfunction evidenced by means of simple, reliable, reproducible tests is frequent in the non-diabetic obese subject. This disorder could explain the poor cardiovascular prognosis associated with obesity. Whether it is a complication of obesity or a marker associated with certain kinds of obesity (of hypothalamic origin) remains to be clarified.

Adolescent↗
PubMed2005

Brain natriuretic peptide and cardiac autonomic function in type 2 diabetic patients.

The present study tested the hypothesis that increased plasma brain natriuretic peptide (BNP) levels are related to cardiac autonomic dysfunction in type 2 diabetic patients. A total of 32 consecutive Japanese patients with type 2 diabetes were assigned to either a high-BNP (>or=18 pg/ml) group (n=12; age 57+/-13 years, mean+/-S.D.) or a normal-BNP (<18 pg/ml) group (n=20; 59+/-10 years). No patient had any overt structural heart disease. Cardiac autonomic function was assessed by measurements of baroreflex sensitivity (BRS), heart rate variability (HRV) and cardiac (123)I-metaiodobenzylguanidine (MIBG) scintigraphic findings. BRS was lower (p<0.005) in the high-BNP group than in the normal-BNP group. However, the components of HRV, and the early and delayed myocardial uptake of (123)I-MIBG and percentage washout rate of (123)I-MIBG were not significantly different between the groups. The plasma level of BNP negatively correlated with BRS (r=0.35, p=0.049). These findings suggest that increased plasma BNP levels were related to cardiac reflex parasympathetic dysfunction in our Japanese type 2 diabetic patients.

3-Iodobenzylguanidine↗
PubMed2001

Cardiac autonomic function in Blacks with congestive heart failure: vagomimetic action, alteration in sympathovagal balance, and the effect of ACE inhibition on central and peripheral vagal tone.

Cardiac autonomic dysfunction is common in heart disease with or without congestive heart failure, and can cause sudden cardiac death. However, cardiac autonomic abnormalities in non-ischemic (hypertensive) heart failure, which is prevalent in Black Africans is poorly documented. We conducted a cross-sectional study of 32 patients with congestive heart failure, mostly secondary to hypertension (aged 52 +/- 15 years, with ejection fraction of 0.38 +/- 11) and 30 age- and sex-matched healthy volunteers (aged 51 +/- 11 years, 14 males/16 females). Cardiac autonomic function was assessed by the Valsalva's maneuver, respiratory sinus arrhythmia (for cardiac vagal tone) and the pressor and chronotropic changes following forearm isometric handgrip exercise and the assumption of upright posture (tests of sympathetic function). The exercise tolerance of the cardiac patients was assessed by the distance covered during 6 min of walking. The Valsalva ratio was significantly lower in chronic heart failure, 1.10 +/- 0.08 compared to the healthy controls 1.47 +/- 0.20 (p<0.001). Specifically, the phase IV bradycardia in heart failure, was significantly attenuated to 650 +/- 121 msec compared to the value of 935 +/- 101 msec in healthy controls (p<0.001). The phase 11 Valsalva tachycardia did not differ between the patients and controls. The respiratory sinus arrhythmia was also significantly reduced in chronic heart failure (p<0.05) compared to controls. Treatment of the heart failure patients with enalapril-digoxin and diuretics by 4 weeks, resulted in a reversal of the autonomic abnormalities. The phase IV bradycardia increased significantly to 798 +/- 164 msec (p<0.01) and the Valsalva ratio to 1.35 +/- 0.25 (p<0.01) and the respiratory sinus arrhythmia increased toward normal. There was close positive correlation between the Valsalva's ratio and the 6 min self paced distance covered (r = 0.44, p = 0.03 ANOVA), and a weak inverse correlation to cardiac size and cardiothoracic ratio (r = -0.31, p = 0.09). This study demonstrates cardiac autonomic dysfunction (especially reduced vagal tone) in Black Nigerians with mainly non-ischemic congestive heart failure. The parasympathetic dysfunction significantly correlates with severity of heart failure. Current treatment reverses autonomic dysfunction to values seen in healthy age matched controls, mainly through augmentation of cardiac parasympathetic activity.

Adult↗
PubMed1990

Ambulatory assessment of cardiac autonomic function in Chagas' heart disease patients based on indexes of R-R interval variation in the Valsalva maneuver.

1. The reflex cardiac autonomic function of Chagas' heart disease patients was evaluated by a simple, noninvasive and inexpensive ambulatory method as an alternative to the complex or invasive methods or drug tests hitherto used. Variations in the R-R interval during the Valsalva maneuver was quantified in 33 outpatients with Chagas' cardiopathy without heart failure aged 38 +/- 9 years, and compared to 30 healthy control subjects aged 31 +/- 8 years (P greater than 0.05). 2. Each subject carried out 3 to 4 Valsalva maneuvers in the supine position for 20 s at an intraoral pressure of 40 mmHg. Variations of R-R interval were calculated from the electrocardiogram which was recorded continuously from 10 s before to 90 s after the maneuver when the recovery phase had already started. 3. The chagasic group presented lower relative tachycardia (shortest R-R minus control R-R/control R-R) (-27.9 +/- 8.4%, mean +/- SD) and Valsalva ratio (longest R-R/shortest R-R) (1.67 +/- 0.3) than the control group (-34.2 +/- 6.5% and 1.93 +/- 0.3, respectively) (P less than 0.01). The time for maximum R-R interval variation (shortest R-R to longest R-R) was longer (18.0 +/- 7.2 s), and the velocity of this variation (longest R-R minus shortest R-R divided by shortest R-R/time for the maximum R-R variation) was lower (4.8 +/- 3.5%/s) in the chagasic patients (P less than 0.01) than in the controls (11.1 +/- 5.4 s and 10.8 +/- 6.0%/s, respectively). The mean relative bradycardia (longest R-R minus control R-R/control R-R) of the chagasic group (18.5 +/- 13.5%) was statistically similar (P greater than 0.05) to that of the control group (25.6 +/- 16.5%). 4. In 51% (17/33) of the chagasic patients, at least one significantly altered index was observed to exceed +/- 2 SD of the respective control mean, and for 3 of them (10% of the total) all the indexes were abnormal. In 49% (16/33) of the patients no abnormal index was observed. 5. These data show that varying degrees of cardiac autonomic dysfunction may be detected in a simple manner in ambulatory outpatients with Chagas' heart disease, with results similar to those obtained with application of complex or invasive tests. In all likelihood, the altered Valsalva R-R interval variation indexes in the present chagasic patients resulted from depressed parasympathetic activity on the heart consequent to the Chagas' cardiac denervation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2006

Cardiac autonomic function in chagasic elderly patients in an endemic area: A time and frequency domain analysis approach.

Chagas' disease is a common cause of cardiac autonomic impairment. In an endemic area there is a predominance of the indeterminate form and the number of elderly individuals committed by the disease is increasing. This study aimed to investigate the profile of heart rate variability (HRV) in elderly chagasic patients. 28 aged chagasic (CH), 28 non-chagasic (NC) aged individuals and 28 adults between 20 and 40 years old (YG) were studied. R-R intervals were assessed in time and frequency domains applying an autoregressive algorithm. There was no difference regarding temporal and spectral indices among the elderly groups in baseline. The values of the variance in CH, NC and YG individuals were 891.80, 283.60, 2557.00, showing a reduction of the total HRV in the aged groups when compared to the young control (p < 0.001). During the cold face test, the pNN50 response was significantly different only in the young group (p < 0.001). The temporal and spectral indices were not different among the elderly groups. The percentile changes of the R-R intervals induced by the tilt test in CH, NC and YG were respectively -7.04%, -9.35%, -15.81%, being significantly higher in the young individuals (p < 0.001). There was no difference regarding the percentile changes of the temporal and spectral indices between CH and NC elderly patients. The cardiac autonomic function assessed by HRV parameters presented no differences among the elderly individuals (CH and NC) living in an endemic area.

Adult↗
PubMed2005

Left ventricular and cardiac autonomic function in survivors of testicular cancer.

BACKGROUND: Following cisplatin-based chemotherapy, survivors of testicular cancer have a high prevalence of cardiovascular risk factors and an increased risk of cardiovascular disease. Cardiac function has not been extensively studied and no comparisons have been made with men from the general population. DESIGN: Left ventricular and cardiac autonomic function were evaluated in chemotherapy-treated testicular cancer patients, in stage I patients after orchidectomy only, and in healthy men using Doppler echocardiography [wall motion score index, peak early (E) and atrial filling (A) velocities across the mitral valve, E/A-ratio, isovolumetric relaxation time, and deceleration time of the early peak flow] and measurements of N-terminal pro-brain natriuretic peptide and baroreflex sensitivity. Furthermore, 24-h ambulatory blood pressure was measured. RESULTS: Ninety chemotherapy-treated patients (median age 37 years, range 20-65; median follow up of 7 years, range 3-13) were compared with 44 stage I patients (median age 36 years, range 24-63) and 47 healthy controls (median age 37 years, range 22-55). Wall motion score index was less than 1.5 in all participants. Chemotherapy-treated patients had a higher peak A-wave and a lower E/A-ratio than stage I patients and controls. Isovolumetric relaxation and deceleration times did not differ between groups. Age, 24-h diastolic blood pressure and treatment with chemotherapy were significantly associated with E/A-ratio. Natriuretic peptide levels were normal. Baroreflex sensitivity was similar in the three groups. CONCLUSIONS: Chemotherapy-treated testicular cancer survivors have a lower E/A-ratio than healthy subjects from the general population, which may indicate impaired relaxation of the left ventricle and reflect the high prevalence of cardiovascular risk factors previously reported in these men.

Adult↗
PubMed2001

Cardiac autonomic function and oesophageal acid sensitivity in patients with non-cardiac chest pain.

BACKGROUND: Acid reflux can elicit non-cardiac chest pain (NCCP), possibly through altered visceral sensory or autonomic function. The interactions between symptoms, autonomic function, and acid exposure are poorly understood. AIM: To examine autonomic function in NCCP patients during exposure to oesophageal acid infusion. SUBJECTS AND METHODS: Autonomic activity was assessed using power spectral analysis of heart rate variability (PSHRV), before and during oesophageal acidification (0.1 N HCl), in 28 NCCP patients (40.5 (10) years; 13 females) and in 10 matched healthy controls. Measured PSHRV indices included high frequency (HF) (0.15-0.5 Hz) and low frequency (LF) (0.06-0.15 Hz) power to assess vagal and sympathetic activity, respectively. RESULTS: A total of 19/28 patients had angina-like symptoms elicited by acid. There were no significant manometric changes observed in either acid sensitive or insensitive patients. Acid sensitive patients had a higher baseline heart rate (82.9 (3.1) v 66.7 (3.5) beats/min; p<0.005) and lower baseline vagal activity (HF normalised area: 31.1 (1.9)% v 38.9 (2.3)%; p< 0.03) than acid insensitive patients. During acid infusion, vagal cardiac outflow increased (p<0.03) in acid sensitive but not in acid insensitive patients. CONCLUSIONS: Patients with angina-like pain during acid infusion have decreased resting vagal activity. The symptoms elicited by perception of acid are further associated with a simultaneous increase in vagal activity in keeping with a vagally mediated pseudoaffective response.

Adult↗
PubMed2004

Clinical study on the effects of nizatidine on gastric motility and cardiac autonomic function. Investigations using electrogastrography and spectral analysis of heart rate variability.

Nizatidine (CAS 76963-41-2, Acinon), an H2 receptor antagonist, not only inhibits acid secretion but also improves gastrointestinal motility. However, autonomic nervous function has not been studied in detail using electrogastrography (EGG). In the present study, two protocols were adopted to study nizatidine's effects on cardiac autonomic function and gastric motility. Protocol I--Acute: "Group C-I": 10 healthy volunteers received a single oral dose of nizatidine 150 mg. Protocol II--Chronic: "Group DM without N": 15 patients with diabetes mellitus (DM) were observed prior to administration of nizatidine. "Group DM with N": The same 15 patients with DM received nizatidine 300 mg/day for more than 30 days. "Group C-II": This control group was composed of 15 healthy volunteers not receiving nizatidine. In all groups, EGGs were recorded before and after a meal, and autonomic nervous function and QT interval of ECG dispersions were simultaneously evaluated. In Group C-I, nizatidine significantly increased the peak power amplitude of 3 cycles/min (cpm) frequency, but did not significantly change the dominant frequency of the 3-cpm waves. In Group DM with N, nizatidine administration significantly increased the peak power amplitude from 2.4 cpm or a lower frequency (bradygastria) to 3 cpm. Prior to nizatidine administration but after eating a meal, the peak power amplitude on EGG was not increased in Group DM without N. In Group DM with N, however, the EGG peak power amplitude increased to levels similar to those of the healthy subjects (Group C-II). Neither the single nor the chronic administration of nizatidine significantly prolonged the QT interval or increased the QT dispersion. A spectral analysis of heart rate variability showed that nizatidine administration, whether acute or chronic, did not significantly change the indices of autonomic nervous activity. Nizatidine may promote gastric emptying by inhibiting acetylcholine esterase, thus increasing cholinergic activity, and by acting directly on gastric smooth muscle. The results indicate that because nizatidine increases gastric motility without exerting a negative influence on the autonomic nerves, it may be a useful drug in patients with diabetic neuropathy.

Anti-Ulcer Agents↗
PubMed1998

Interictal change in cardiac autonomic function associated with EEG abnormalities and clinical symptoms: a longitudinal study following acute deterioration in two patients with temporal lobe epilepsy.

The purpose of the present study was to investigate the ictal and interictal changes in cardiac autonomic function (CAF), and the relationship between the interictal change in CAF to the electroencephalogram (EEG) and clinical findings. In two patients with temporal lobe epilepsy (TLE) showing acute deterioration, a quantitative evaluation of their interictal CAF based on heart rate variability and their EEG using spectral analysis was conducted, and the findings compared with repeated clinical evaluations during the recovery period. The ictal heart rate changes and their temporal relationship to ictal discharge were investigated using simultaneous EEG/electrocardiogram (ECG) monitoring in one of the patients. Interictal parasympathetic function was decreased during the period of acute deterioration, but was increased in association with improvements in the EEG and clinical findings. In contrast, the sympathetic function showed no specific changes. The ictal discharges were preceded by a brief bradycardia, with a long delay of up to 40s. The results demonstrated that this decrease in parasympathetic function was closely related to the interictal changes in central nervous system function. On the other hand, the ictal discharges in one of the patients were thought to have caused a transient elevation of parasympathetic function. It is strongly suggested that patients with TLE have interictal as well as ictal changes in CAF that are mediated mainly through the parasympathetic nervous system.

Adult↗