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PubMed1998

Dopamine and dobutamine have different effects on heart rate variability in patients with congestive heart failure.

BACKGROUND: Autonomic dysfunction plays an important role in the pathogenesis, treatment and prognosis of congestive heart failure (CHF). Sympathomimetic amines have been widely used in the treatment of CHF, but reports on their autonomic effects in CHF are rare. This study was designed to evaluate the effects of dopamine and dobutamine on cardiac autonomic function as assessed by heart rate variability (HRV). METHODS: Twenty patients with symptomatic CHF (systolic dysfunction) were enrolled. After recording one-hour baseline electrocardiographs (ECGs), patients were randomly selected for either dopamine (4 micrograms/kg/minute, Group A) or dobutamine (4 micrograms/kg/minute, Group B) treatment for three days. On the third day, a 24-hour ambulatory ECG was recorded and a tilt-table test was performed. Only furosemide and nitrates were allowed for adjunctive therapy. HRV was measured before and after treatment in both time and frequency domains. Frequency-domain HRV was also measured during head-up tilt. RESULTS: After treatment, all patients improved [New York Heart Association fraction (NYHA Fc) 3.7 to 2.0]. Group A patients had higher post-treatment 24-hour HRV than those in Group B. SDNN (standard deviation of the average normal RR intervals in the entire ECG recording), SDANN (standard deviation of the average normal RR intervals for all five minute segments of an entire ECG recording) and SDNN indices in Group A were significantly higher than in Group B (90 +/- 33 ms vs 41 +/- 12 ms, 78 +/- 32 ms vs 36 +/- 11 ms, and 37 +/- 19 ms vs 16 +/- 7 ms, respectively, all p < 0.05). rMSSD (the square root of the mean of the squared differences between adjacent normal RR intervals over the entire ECG recording) and pNN50 (percentage of differences between adjacent normal RR intervals that are greater than 50 ms computed over the entire ECG recording) were also higher in Group A patients, with borderline significance. All measurements of total frequency and low-frequency and high-frequency components tended to be higher in Group A than Group B, but this was only significant for total frequency amplitude (22.9 +/- 13.4 ms vs 10.9 +/- 6.1 ms, p < 0.05). Dopamine but not dobutamine treatment seems to restore the depressed circadian change in frequency-domain HRV classically seen in patients with CHF. The HRV change during head-up tilting did not differ between the two groups. Three patients in Group B showed non-sustained ventricular tachycardia on ambulatory ECG during the treatment period. CONCLUSIONS: Dopamine and dobutamine have comparable therapeutic effects in patients with CHF, but low-dose dopamine more favorably affects cardiac autonomic function.

Aged↗
PubMed1997

Cardiovascular autonomic dysfunction in sickle cell anemia: a possible risk factor for sudden death?

Cardiovascular autonomic function tests were performed in 24 patients with sickle cell anemia (SCA). Twenty-five healthy Afro-Caribbean black subjects and 38 healthy white subjects of Hispanic origin served as controls. Measurements based on heart rate variability (HRV) included the coefficient of variation (the standard deviation of the distribution of R-R intervals divided by the mean) and spectral analysis (low- and high-frequency bands) at rest, HRV during deep breathing (expiration-inspiration difference), Valsalva maneuver (Valsalva ratio) and lying-to-standing test (30:15 ratio). Fourteen patients (58.3%) were found to have cardiovascular autonomic dysfunction based on abnormal values for at least two cardiovascular autonomic function tests, whereas ten (41.7%) had preserved cardiovascular autonomic function. In contrast, all control subjects had normal cardiac autonomic function. SCA is known to be associated with sudden death. Involvement of autonomic nervous dysfunction in sudden death has been reported in various diseases and we suggest that this may be the case in SCA.

Adolescent↗
PubMed1993

Effect of atropine on the QT interval and T-wave amplitude in healthy volunteers.

Prolongation of the QT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal activity protects against prolongation of the QT interval which may be associated with flattening of the T-wave of the ECG. The changes in QT interval, T-wave amplitude and respiratory sinus arrhythmia (RSA) were studied after i.v. administration of atropine 20 micrograms kg-1 or placebo to 10 healthy volunteers in a cross-over study. After atropine, a decrease in RSA occurred in all volunteers, but remained at baseline values after placebo. Corrected QT interval (QTc) increased from 410 (20) ms to 454 (11) ms (P < 0.001) 5 min after atropine and remained prolonged for the entire study period (60 min). The T-wave flattened significantly (measured as R:T ratio) up to 30 min, without any changes in the R-wave. No changes in the ECG occurred with placebo.

Adult↗
PubMed1991

The vestibulo-autonomic function viewed from cardiac responses in centrifuged monkeys.

Vestibulo-autonomic function was examined as the change of cardiac parameters (HR and SV) to +Gz and -Gx accelerations for 1,000 s in intact and bilaterally labyrinthectomized monkeys. Under anesthetized conditions, HR and SV slightly changed to +2Gz acceleration in both monkeys. In +3Gz acceleration, changes were remarkable and significant. HR increased in intact monkeys by as much as 30% while it decreased in labyrinthectomized monkeys, although a moderate initial increase was observed. SV decreased in intact as well as labyrinthectomized monkeys, but the reduction was significant and larger for the latter. This implies that vestibular input could modulate autonomic function. For larger +Gz, both intact and labyrinthectomized monkeys could tolerate no more due to severe cardiac dysfunction (rapid HR and SV decrease) which appeared soon after +4Gz application. In case of -Gx application, HR increased, although slightly, in proportion to the amplitude of applied -Gx in both monkeys, with less changes in labyrinthectomized ones. SV hardly changed in smaller -Gx, while it increased in larger -Gx. Difference between intact and labyrinthectomized monkeys was observed in -6Gx and -8Gx conditions.

Acceleration↗
PubMed1999

Aging alteration of cardiac vagosympathetic balance assessed through the tone-entropy analysis.

BACKGROUND: Age-associated alterations of cardiac autonomic functions have been investigated intensively through heart rate variability analyses. However, changes with age in cardiac vagosympathetic balance remain to be elucidated. METHODS: We studied 142 male subjects (30-69 yr) at a health care center in Kyoto, Japan. Electrocardiographic data were collected from subjects in a recumbent position for 10 min in the morning. Analysis was done by classifying the subjects into four age groups. In a pharmacological experiment carried out in December 1996, tone was verified to reflect the cardiac vagosympathetic balance, and entropy the total autonomic neural efferent activity. We assessed the heart rate variability through the tone-entropy (T-E) analysis that was described previously. In essence, two indexes, tone and entropy, were defined on a distribution of successive variations of heart period. RESULTS: No significant differences were detected in clinical conditions among the four age groups. Tone increased and entropy decreased significantly with age. The aging process was expressed as a curvilinear path in T-E space. Compared to the pharmacological experiment, it was observed that aging degenerated the heart function from an ordinary to a denervated one. The same aging path was superimposed in the opposite direction on the heart recovery path after dynamic exercise in which cardiac vagosympathetic balance tended toward vagus division, corresponding with restoration of total autonomic activity. CONCLUSIONS: An age-related reduction in cardiac autonomic function was consistent with previous reports. The vagosympathetic balance was altered with this reduction: vagal predominance was impaired significantly in proportion to the withdrawal of total cardiac autonomic activity.

Adrenergic beta-Antagonists↗
PubMed1995

Impaired low-frequency oscillations of heart rate in patients with prior acute myocardial infarction and life-threatening arrhythmias.

Myocardial infarction results in abnormal cardiac autonomic function, which carries an increased risk of cardiac mortality, but it is not well known whether autonomic dysfunction itself predisposes patients to life-threatening arrhythmias or whether it merely reflects the severity of underlying ischemic heart disease. To determine the significance of abnormalities of cardiovascular neural regulation on the risk for ventricular tachycardia (VT), heart rate (HR) variability in the time and frequency domain were compared in a case-control study between 30 patients with a prior myocardial infarction and a history of sustained VT (n = 18) or cardiac arrest (n = 12) (VT group) and 30 patients with a prior myocardial infarction but no arrhythmic events (control group). The patient groups were carefully matched with respect to age, sex, location, ejection fraction, number of prior infarctions, number of diseased coronary arteries, and beta-blocking medication. In all patients in the VT group, inducibility into sustained VT was achieved, but none of the control patients had inducible nonsustained or sustained VT during programmed electrical stimulation. Patients in the VT group had a significantly lower SD of the RR intervals (p < 0.01), and reduced ultra low-, very low-, and low-frequency power spectral components of HR variability (p < 0.001 for all) than controls, but the high-frequency component of HR variability did not differ significantly between groups. In multiple regression analysis, reduced very low-frequency power of HR variability was the strongest independent predictor of VT susceptibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed2006

Low-level lead exposure, metabolic syndrome, and heart rate variability: the VA Normative Aging Study.

BACKGROUND: Altered heart rate variability (HRV), a marker of poor cardiac autonomic function, has been associated with sudden cardiac death and heart failure. OBJECTIVE: We examined the association of low-level lead exposure measured in bone by K-X-ray fluorescence with alterations in HRV, and whether metabolic syndrome (MetS) or its individual components modify those associations. METHODS: HRV measures [power in high-frequency (HFnorm) and low-frequency (LFnorm) in normalized units, and LF/HF] were taken among 413 elderly men from the Normative Aging Study. MetS was defined as subjects having three or more of the following criteria: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein, high blood pressure, and high fasting glucose. RESULTS: Of the subjects, 32% were identified as having MetS. Inverse but nonstatistically significant associations of both tibia and patella lead levels with HFnorm and nonstatistically significant positive relations with LFnorm and LF/HF were found in the entire cohort. There was a graded, statistically significant reduction in HFnorm and increases in LFnorm and LF/HF in association with an increase in patella lead as the number of metabolic abnormalities increased. We also observed that higher patella lead was consistently associated with lower HFnorm and higher LFnorm and LF/HF among subjects with MetS or its individual components. No statistically significant interaction between MetS and tibia lead was observed. CONCLUSION: The results suggest that elderly men with MetS were more susceptible to autonomic dysfunction in association with chronic lead exposure as measured in patella. The modification by MetS is consistent with a role for oxidative stress in lead toxicity on the cardiovascular system.

Adult↗
PubMed2000

The defibrillator in acute myocardial infarction trial (DINAMIT): study protocol.

BACKGROUND: The implantable cardioverter/defibrillator (ICD) has been shown to be superior to antiarrhythmic drug therapy for the secondary prevention of sudden cardiac death. Its role in the primary prevention of sudden death after myocardial infarction is unknown. Methods and Results The Defibrillator in Acute Myocardial Infarction Trial (DINAMIT) is a randomized, open-label, parallel-group comparison of ICD therapy versus no ICD therapy in selected survivors of acute myocardial infarction. It will test the hypothesis that reduction of sudden arrhythmogenic death by means of the ICD will result in reduction of overall mortality rates in patients at high risk after acute myocardial infarction. Accordingly, this international multicenter study aims to enroll patients shortly after their infarction (day 6 to day 40) who have reduced left ventricular function (left ventricular ejection fraction </=0. 35) and impairment of cardiac autonomic function shown by depressed heart rate variability (standard deviation of normal-to-normal R-R intervals </=70 ms) or elevated average 24-hour heart rate (mean 24-hour R-R interval </=750 ms, assessed by Holter monitoring). Patients will be followed for approximately 3 years on average with subsequent data analysis based on the intent-to-treat principle. Primary outcome is all-cause death. The trial is expected to be completed in 2003. CONCLUSIONS: DINAMIT is the first prospective study to evaluate the benefit of ICD therapy for the primary prevention of sudden cardiac death in patients at high risk after acute myocardial infarction.

Defibrillators, Implantable↗
PubMed1998

An automatic device for the assessment of cardiovascular autonomic function.

Autonomic neuropathy is a common complication of diabetes mellitus and is associated with significant morbidity and possibly an increase in mortality. Despite this, however, autonomic dysfunction is not usually sought in the routine assessment of diabetic patients. We report the development and testing of a small, portable and reliable device that allows the routine testing of cardiac autonomic function in the outpatient setting with minimal inconvenience to the patient. This should facilitate the accurate assessment both of patients with symptoms suggestive of autonomic dysfunction and of autonomic function in research.

Arrhythmias, Cardiac↗
PubMed2004

The influence of major depression and its treatment on heart rate variability and pupillary light reflex parameters.

BACKGROUND: The link between depression and autonomic dysfunction has attracted more attention since epidemiological studies have revealed that depressed patients have an augmented risk of cardiovascular morbidity and mortality. Former studies of autonomic dysfunction in major depression have shown inconclusive results. AIMS: To further elucidate the effect of depression and medication on autonomic function, 18 patients and 18 matched control subjects were comprehensively assessed once medicated and once non-medicated as well as after full clinical recovery. METHODS: Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters, and central autonomic tone was investigated by obtaining parameters of the pupillary light reflex (PLR). RESULTS: Acutely depressed patients who had not taken antidepressant medication for 8 weeks prior to the investigation differed significantly neither in heart rate parameters nor in parameters of the PLR from their controls. However, after 2 days of antidepressant treatment (SSRI and NaSSRI), parameters of heart rate analysis and PLR (except relative amplitude) changed significantly and remained significantly different after clinical recovery. LIMITATIONS: The study needs to be repeated using larger patient groups. Long-term studies are absolutely essential. CONCLUSION: The state of depression did not influence autonomic parameters significantly. In fact, treatment influenced autonomic function far more than the disease itself. Other branches of the autonomic nervous system (ANS), as well as new techniques should be applied to elucidate whether small changes in autonomic function exist. This might clarify whether disease or treatment might influence cardiac mortality in depression.

Adult↗
PubMedDate not supplied

Intracardiac autonomic ganglion cells in leprosy and dilated cardiomyopathy.

Disturbances in cardiac autonomic functions are known to occur in patients of lepromatous leprosy and dilated cardiomyopathy. We have analyzed the number of cardiac autonomic ganglion cells in patients of lepromatous leprosy (2 cases), dilated cardiomyopathy (2 cases) and compared with those of control subjects (2 cases). The average number of ganglion cells in cases of dilated cardiomyopathy (1164) and leprosy (1138) did not show any significant deviation from the average neuronal number of control subjects (1352).

Adult↗
PubMed2004

Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with various heart conditions who are at high risk for ventricular arrhythmias. Whether benefit occurs in patients early after myocardial infarction is unknown. METHODS: We conducted the Defibrillator in Acute Myocardial Infarction Trial, a randomized, open-label comparison of ICD therapy (in 332 patients) and no ICD therapy (in 342 patients) 6 to 40 days after a myocardial infarction. We enrolled patients who had reduced left ventricular function (left ventricular ejection fraction, 0.35 or less) and impaired cardiac autonomic function (manifested as depressed heart-rate variability or an elevated average 24-hour heart rate on Holter monitoring). The primary outcome was mortality from any cause. Death from arrhythmia was a predefined secondary outcome. RESULTS: During a mean (+/-SD) follow-up period of 30+/-13 months, there was no difference in overall mortality between the two treatment groups: of the 120 patients who died, 62 were in the ICD group and 58 in the control group (hazard ratio for death in the ICD group, 1.08; 95 percent confidence interval, 0.76 to 1.55; P=0.66). There were 12 deaths due to arrhythmia in the ICD group, as compared with 29 in the control group (hazard ratio in the ICD group, 0.42; 95 percent confidence interval, 0.22 to 0.83; P=0.009). In contrast, there were 50 deaths from nonarrhythmic causes in the ICD group and 29 in the control group (hazard ratio in the ICD group, 1.75; 95 percent confidence interval, 1.11 to 2.76; P=0.02). CONCLUSIONS: Prophylactic ICD therapy does not reduce overall mortality in high-risk patients who have recently had a myocardial infarction. Although ICD therapy was associated with a reduction in the rate of death due to arrhythmia, that was offset by an increase in the rate of death from nonarrhythmic causes.

Adult↗
PubMed1997

Limited utility of the phenylephrine-nitroprusside sigmoid curve method of measuring baroreflex function after myocardial infarction.

BACKGROUND: Conventional testing of baroreflex function with phenylephrine bolus injection measures reflex vagal tone. OBJECTIVE: To evaluate an alternative pharmacological method of baroreflex testing, which might provide more comprehensive evaluation of the baroreflex function in patients with uncomplicated myocardial infarction. METHODS: Forty-eight patients, aged 59 +/- 7 years, were evaluated 5-7 days after myocardial infarction and after 6 weeks of rehabilitation. Baroreflex testing was performed with 10-14 incremental injections of nitroprusside and phenylephrine. The peak heart rate and blood pressure point from each injection were fitted to a four parameter (upper plateau, lower plateau, gain and median blood pressure) sigmoid logistic function. The baroreflex sensitivity (BRS) was also measured by conventional linear analysis of the response of the R-R interval to the initial rise in systolic blood pressure induced by phenylephrine bolus injection. RESULTS: Non-linear curve fitting of four logistic curve parameters was possible for results from 91% of tests; in the remaining tests the upper plateau was held constant at the maximum heart-rate response to allow estimation of the other three parameters. When all four parameters had been estimated, the gain parameter could not be precisely determined (the coefficient of variation of the gain parameter was 85 +/- 10%). The upper (R = 0.72, P < 0.001) and lower plateaux (R = 0.76, P < 0.001) were strongly related to the resting heart rate and weakly related to measures of heart-rate variability. There was also a significant inverse correlation between the lower plateau and the BRS (R = -0.57, P < 0.001). The gain parameter was not related to the BRS or any measure of the heart-rate variability. After 6 weeks' rehabilitation there was a significant decrease in the lower plateau (from 54 +/- 2 to 48 +/- 1 beats/min, P < 0.001), an increase in BRS (from 9.4 +/- 0.8 to 12.1 +/- 0.8 ms/mmHg, P < 0.001) and no change in the other three sigmoid curve parameters. CONCLUSIONS: Non-linear curve fitting of the heart-rate-blood-pressure relationship for patients after myocardial infarction is feasible but technical limitations and the lack of correlation between the gain parameter and other measures of autonomic function suggest that this method has limited usefulness. The lower plateau is related strongly to the BRS; both are vagal measures of cardiac autonomic function.

Aged↗
PubMed2005

Effects of subchronic exposures to concentrated ambient particles (CAPs) in mice. IV. Characterization of acute and chronic effects of ambient air fine particulate matter exposures on heart-rate variability.

Long-term exposure to fine particulate air pollution (PM2.5) has been associated increased risk of death from cardiopulmonary diseases. Cardiac function parameters have also been affected by ambient particulate matter (PM) exposure, including heart-rate variability (HRV), a measure of autonomic function that has been recognized as a well-defined, quantitative indicator of autonomic dysfunction. However, the role of HRV in ambient PM-induced cardiovascular effect is not fully understood. In an accompanying article, we report significant decreasing patterns of heart rate (HR), body temperature, and physical activity for mice lacking apoliproprotein (ApoE-/-) over 5 mo of exposure to concentrated ambient PM (CAPs), with smaller and nonsignificant change for C57 mice. In this article, we report the effects of subchronic CAPs exposure on HRV parameters that are sensitive to cardiac sympathetic and parasympathetic nerve activity. The standard deviation of normal to normal beat intervals (SDNN) and the square root of the mean squared differences of successive RR intervals (RMSSD) in the late afternoon and overnight for the ApoE-/- mice showed a gradual increase for the first 6 wk, a decline for about 12 more wk, and a slight turn upward at the end of the study period. For C57 mice, there were no chronic effect changes of SDNN or RMSSD in the late afternoon, an a slight increase after 6 wk for the overnight period. The response patterns of ApoE-/- mice indicated a perturbation of the homeostatic function in the cardiovascular system (initial enhancement and late depression of the HRV parameters). Our results complement the findings in human panel and controlled CAPs exposure studies in demonstrating that increased levels of particle pollution are able to perturb cardiac autonomic function, which may lead to adverse cardiovascular outcomes.

Air Pollutants↗
PubMed1985

Similarities and differences in the effects of verapamil, diltiazem and nifedipine on arterial baroreflexes of anesthetized cats.

The effects of verapamil, diltiazem and nifedipine on baroreflex sensitivity (BS) were investigated in anesthetized cats at equihypotensive doses of 100, 100 and 10 micrograms/kg, respectively. The gain in BS (ms/mmHg) was calculated from the ratio delta heart period/delta systolic pressure following evoked rises and falls in arterial pressure. Verapamil and diltiazem significantly augmented BS while nifedipine depressed BS during evoked rises in arterial pressure. By contrast, BS was significantly depressed by diltiazem and nifedipine in response to depressor challenges with nitroprusside, while it was unaffected by verapamil. The augmentatory action of verapamil on BS after pressor challenges, was abolished by bilateral vagotomy while the inhibitory action of nifedipine was still evident after vagotomy, suggesting a vagal augmentatory action for verapamil and an involvement of the cardiac sympathetic nerves in the inhibitory action of nifedipine on BS. The differences between the actions of the 3 drugs on BS are not readily explainable by our data but they cannot be attributed to alterations of cardiac autonomic function since at the doses employed none of the drugs affected the cardiac responses to carotid occlusion, i.v. isoproterenol or electrical stimulation of the right vagus. It is concluded that BS is affected differently by the 3 chemically unrelated calcium channel blockers in a way which could either be contributory or deleterious to the antihypertensive effectiveness of these drugs.

Anesthesia↗
PubMed1995

[The significance of heart rate analysis in psychiatric questions].

Heart rate analyses have become an important diagnostic tool for the assessment of autonomic nervous system function. Measurements of heart rate variability (HRV) have been frequently used to establish criteria for a cardiovascular autonomic neuropathy (CAN). Methods of HRV have also been applied to unmedicated patients with psychiatric disorders and to investigate the impact of psychotropic drugs on autonomic cardiac functions. In one of our studies 20% of patients with alcohol dependence (n = 60) fulfilled the criteria of CAN as a result of vagal neuropathy. In other psychiatric disorders clearcut abnormalities of autonomic regulation have not yet been found. However, there is an increasing number of pointers suggesting that patients with panic disorders show a predominance of sympathetic cardiac control, while patients with melancholic depression might show a lack of parasympathetic control. Under the condition of treatment with either 150 mg of a tricyclic antidepressant (TCA) or 300 mg of clozapine per day, HRV-parameters were found to be significantly decreased and the majority of the patients fulfilled the criteria of CAN, whereas the selective inhibitors of serotonin (SSRI) given in usual dosages had no effect on HRV-parameters. In another study with depressed patients treated with TCA, HRV-parameters were found to be helpful in understanding mood-altering chronobiological mechanisms. The results presented make clear that research on autonomic functions is not only useful in neurological diseases, but also in psychiatric disorders especially under the conditions of psychopharmacological treatment.

Autonomic Nervous System↗
PubMed1999

Noninvasive exploration of cardiac autonomic neuropathy. Four reliable methods for diabetes?

OBJECTIVE: The purpose of this work was to assess relevant information that could be provided by various mathematical analyses of spontaneous blood pressure (BP) and heart rate (HR) variabilities in diabetic cardiovascular neuropathy. RESEARCH DESIGN AND METHODS: There were 10 healthy volunteers and 11 diabetic subjects included in the study. Diabetic patients were selected for nonsymptomatic orthostatic hypotension in an assessment of their cardiovascular autonomic impairment. Cardiac autonomic function was scored according to Ewing's methodology adapted to the use of a Finapres device. The spontaneous beat-to-beat BP and HR variabilities were then analyzed on a 1-h recording in supine subjects. The global variabilities were assessed by standard deviation, fractal dimension, and spectral power. The cardiac baroreflex function was estimated by cross-spectral sequences and Z analyses. RESULTS: In diabetic patients, Ewing's scores ranged from 1 to 4.5, confirming cardiovascular autonomic dysfunction. In these diabetic patients, global indices of variabilities were consistently lower than in healthy subjects. Furthermore, some of them (standard deviation and fractal dimension of HR, spectral power of systolic blood pressure and HR) were significantly correlated with the Ewing's scores. The Z methods and the spectral analysis found that the cardiac baroreflex was less effective in diabetic subjects. However, the baroreflex sensitivity could not be reliably assessed in all the patients. The sequence method pointed out a decreased number of baroreflex sequences in diabetic subjects that was correlated to the Ewing's score. CONCLUSIONS: Indices of HR spontaneous beat-to-beat variability are consistently related to the degree of cardiac autonomic dysfunction, according to Ewing's methodology. The Z method and spectral analysis confirmed that the cardiac baroreflex was impaired in diabetic patients. These methods might be clinically relevant for use in detecting incipient neuropathy in diabetic patients.

Adult↗
PubMed2001

Cardiac autonomic denervation and functional response to neurotoxins during acute experimental Chagas' disease in rats.

Severe cardiac autonomic denervation occurs in the acute Chagas' disease in rats. The present study aims at verifying whether this denervation was accompanied by impairment of heart function. Scorpionic (Tityus serrulatus) crude venom was used for neurotransmitter release in isolated hearts (Langendorff's preparation). In control hearts, the venom induced significant bradycardia followed by tachycardia. In infected animals, despite the severe (sympathetic) or moderate (parasympathetic) cardiac denervation, the venom provoked similar bradycardia but the tachycardia was higher. The hearts of infected animals beat at significantly lower rate. Atropine prevented this lower rate. Our results demonstrated sympathetic dysfunction during the acute phase of Trypanosoma cruzi infection in rats, the parasympathetic function being spared.

Acetylcholine↗