Cardiac Autonomic Control In Patients Research Articles

Oxidative stress associated with impaired autonomic control and severity of lung function in chronic obstructive pulmonary disease patients.

Oxidative stress has been suggested to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to investigate a link between malondialdehyde (MDA) levels, pulmonary function, and cardiac autonomic control in patients with COPD. Plasma levels of MDA, heart rate variability, and pulmonary function were measured in 50 clinically stable COPD patients and 50 normal male controls. COPD patients exhibited lower means of the standard deviations of all normal to normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), and high frequency (HF). Nevertheless, they presented greater low frequency (LF) and low frequency/high frequency ratio (LF/HF ratio) in supine and head-up tilt positions than controls (P<0.001). More-over, a negative correlation between MDA levels with SDNN (P<0.001) and a positive correlation with LF (P<0.01) and LF/HF ratio (P<0.05) were observed in both positions. In COPD patients, plasma MDA levels were 2.3 times greater than controls (4.33±2.03 μM vs. 1.89±0.39 μM, P<0.001), and they were inversely correlated with forced vital capacity, forced expiratory volume in 1 sec, midexpiratory flow, and peak expiratory flow (P<0.001). Our findings suggest a potential role for oxidative stress in impaired cardiac autonomic control and clinical relevance of plasma MDA levels as a predictor of severity of COPD in COPD patients.

Perampanel enhances the cardiovagal tone and heart rate variability (HRV) in patients with drug-resistant temporal lobe epilepsy

ObjectiveThe temporal lobe plays a central role in the regulation of the "Central Autonomic Network" and cardiovascular functions. The blockade of glutamatergic pathways in the temporal lobe affects cardio-autonomic control. Perampanel (PER) is a non-competitive agonist of the AMPA receptor. This study evaluated PER effects on cardiac autonomic control in patients affected by drug-resistant TLE (DRTLE). MethodsWe enrolled 40 adults with DRTLE treated with PER as add-on therapy (PER group) and 32 DRTLE age, sex, and seizure-frequency matched controls treated with different additional anti-seizure medication (ASM) as add-on therapy (No-PER group). HRV analysis was performed on 5-minute EKG recording in resting state before and 6-months after the introduction of add-on ASM. Linear Mixed Models (LMM) were used to analyzed HRV variables according to time (baseline and 6-months follow-up) and groups. ResultsAt baseline no differences were detected between PER group and No-PER group according to time-domain and frequency-domain HRV parameters. At the follow-up, in PER group a multiplicative effect for the interaction between treatment and time was observed for MeanRR (ms) (p=0.03), LnRMSSD (ms) (p=0.04), LnHF (ms2) (p<0.001), HF n.u. (p=0.001), HF% (p=0.002) with increased values, and for LnLF (ms2) (p=0.001), LF n.u. (p=0.001), LF% (p=0.01), and LF/HF (p<0.001) with reduced values. The change in seizure frequency after add-on therapy was comparable between the two groups (p=0.81) ConclusionsOur data support the notion that PER increases the vagal tone in DRTLE. This activity may exert a cardioprotective effect by reducing the risk of developing cardiac arrhythmias. Furthermore, given the correlations between HRV modifications and the occurrence of SUDEP, future studies will need to test the protective effects of PER on SUDEP.

Comparison of the effects of new anti-seizure drugs (ASDS) on cardiac autonomic control in patients with temporal lobe epilepsy (TLE)

Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy in adulthood. Temporal lobe plays a central role in the regulation of cardio-autonomic functions (CAF) which can be also influenced by several anti-seizure therapies. The spectral analysis of the Heart Rate Variability (HRV) represents a useful tool for the evaluation of CAF. The aim of this study is to assess, using the spectral analysis of HRV, new anti-seizure medication (ASMs) - Perampanel (PER), Lacosamide (LCS), Eslicarbazepine (ECB) and Brivaracetam (BRV) - effects on CAF in patients with TLE.

Effect of the combination of automated peripheral mechanical stimulation and physical exercise on aerobic functional capacity and cardiac autonomic control in patients with Parkinson\u2019s disease: a randomized clinical trial protocol

BackgroundAutomated peripheral mechanical stimulation (AMPS) has been proposed as a new complementary therapy with potential for improving motor and cardiovascular abnormalities in Parkinson’s disease (PD). However, AMPS long-term effects and its combination with physical exercise are unknown. Thus, this study aims to compare the effects of a program of 12 weeks of physical exercise with a 12-week intervention program combining physical exercise and AMPS on the aerobic capacity, cardiac autonomic control, and gait parameters in patients with PD.MethodsA randomized, controlled clinical trial will be conducted. Older volunteers with PD will be randomly assigned to one of the two groups studied: (1) exercise or (2) AMPS + exercise. Both groups will undergo an exercise program of 24 sessions, for 12 weeks, performed twice a week. Before exercise sessions, the group AMPS + exercise will receive a session of active AMPS, while the group exercise will receive an AMPS sham intervention. Shapiro-Wilk’s and Levene’s tests will be used to check for data normality and homogeneity, respectively. In case parametric assumptions are fulfilled, per-protocol and intention-to-treat analyses will be performed using a mixed model analysis of variance to check for group*time interaction. Significance level will be set at 5%.DiscussionSeveral non-pharmacological treatment modalities have been proposed for PD, focusing primarily on the reduction of motor and musculoskeletal disorders. Regular exercise and motor training have been shown to be effective in improving quality of life. However, treatment options in general remain limited given the high prevalence and adverse impact of these disorders. So, developing new strategies that can potentiate the improvement of motor disabilities and also improve non-motor symptoms in PD is relevant. It is expected that the participants from both groups will improve their quality of life, gait parameters, and their cardiac autonomic control, with greater improvements being observed in the group combining active AMPS and physical exercise.Trial registrationClinicalTrials.gov NCT04251728. Registered on February 05, 2020.

One Session of Spinal Manipulation Improves the Cardiac Autonomic Control in Patients with Musculoskeletal Pain: A Randomized Placebo-Controlled Trial.

Three-arm, parallel, randomized, placebo-controlled, assessor-blinded trial. To compare the immediate effect of manual therapy at the upper thoracic spine on the cardiovascular autonomic control of patients with musculoskeletal pain. Musculoskeletal pain increases the risk of cardiovascular events. Thus, manual therapy applied to the upper thoracic region is likely efficient to improve the cardiac autonomic control. The study included 59 patients with musculoskeletal pain enrolled at an outpatient clinic. Participants were randomly assigned to spinal manipulation (n = 19), myofascial manipulation (n = 20), or placebo (n = 20) administered to the upper thoracic region. Resting heart rate variability provided indexes of the cardiac autonomic control, and the blood pressure response to the cold pressor test as a proxy of the sympathetic responsiveness to a stressor stimulus. Groups were similar for baseline variables except for blood pressure. Two-way repeated-measures one-way analysis of covariance (ANCOVA) revealed that only spinal manipulation induced immediate increase of the square root of the mean squared differences of successive RR intervals (RMSSD), absolute (ms2), and normalized units (n.u.) of the high-frequency power (HF) as compared with pre-intervention evaluation, indicating an improvement in the parasympathetic activity to the heart. Normalized units of low-frequency power (LF) and the LF/HF ratio reduced after the spinal manipulation solely, suggesting a reduction of the sympathetic activity to the heart. There were no significant differences in the blood pressure responsiveness among the three treatments. There were no adverse events. In patients with musculoskeletal pain, spinal manipulation on the upper thoracic spine led to an immediate improvement in the resting cardiac autonomic control without an effect on the blood pressure responsiveness to a sympathoexcitatory stimulus. Myofascial manipulation or placebo did not change cardiovascular autonomic control.Level of Evidence: 2.

Immediate Effects of Rib Mobilization and Diaphragm Release Techniques on Cardiac Autonomic Control in Patients With Chronic Obstructive Pulmonary Disease: A Pilot Study

ObjectiveThe purpose of this pilot study was to evaluate the feasibility of testing an intervention protocol and measuring the immediate effects of a rib mobilization technique (RMT) and a diaphragm release technique (DRT) on the autonomic nervous system of patients with chronic obstructive pulmonary disease (COPD). MethodsThis was a pilot study of a randomized controlled trial. Fourteen individuals were evaluated. Eligibility criteria were being a sedentary person with a diagnosis of COPD, age between 50 and 72 years, and being clinically stable. Exclusion criteria were heart disease, other respiratory comorbidities, and body mass index above 30kg/m2. Participants first underwent cardiorespiratory evaluation and were then allocated into 2 groups: the RMT + DRT group and the DRT group. Clinical assessments were performed immediately before and after the intervention. Statistical analysis was carried out through a paired-sample Wilcoxon test, and the comparison between groups was performed using the Mann-Whitney test. ResultsAll randomized participants completed the assessment and intervention protocol. Sample size was estimated at 24 individuals per group. The DRT group decreased resting heart rate by 5 bpm (P = .03) and increased variance (P = .04) and mean R-R interval (P = .03). The RMT + DRT group decreased mean R-R interval (P = .02). ConclusionThe design for this study appears to be feasible for evaluating manual-therapy intervention in the nonmusculoskeletal function of patients with COPD. It was possible to determine the sample size for future studies. Preliminary data show that the diaphragm release technique may reduce mean resting heart rate and increase heart-rate variability immediately after the intervention.

Influence of physical activity on cardiac autonomic control in patients with dyslipidaemia

The objective of this study was to compare the cardiac autonomic control of dyslipidaemia patients engaged in different levels of physical activity and to determine the predictive ability of physical activity for cardiac autonomic dysfunction in these patients. This study also aimed to compare the cardiac autonomic control of dyslipidaemia patients and healthy adults. 52 patients (age: 49.1±4.53 years) with dyslipidaemia were recruited along with 16 healthy adults. Physical activity levels were assessed by International Physical Activity Questionnaire, and subjects were divided into three categories – low, moderate, and high physical activity. Heart rate variability (HRV) analysis was performed for obtaining time and frequency domain parameters. Presence of cardiac autonomic dysfunction was defined as standard deviation of N-N intervals &lt;44 ms. HRV parameters were compared between 3 groups of dyslipidaemia patients and healthy controls. Predictive ability of physical activity for cardiac autonomic dysfunction in dyslipidaemia was evaluated after adjusting clinical covariates. There was a significant difference between low-frequency power (cardiac sympathetic control), and ratio of low- and high-frequency (HF) power (sympatho-vagal balance) in low versus moderate physical activity group and low versus high physical activity group (P&lt;0.001). Significant differences were also observed for HFnu power (cardiac vagal activity) and total power between the dyslipidaemia groups. Physical activity was found to be a significant (P=0.03), independent predictor of cardiac autonomic dysfunction in dyslipidaemia patients. Findings of the present study suggest that cardiac autonomic profile of dyslipidaemia patients with different physical activity levels varied significantly. Dyslipidaemia patients engaged in moderate and high physical activity demonstrated significantly less sympathetic activity and better sympatho-vagal balance than those engaged in low levels of physical activity; also, vagal cardiac control was significantly greater in high physical activity group. Lower levels of physical activity determined the presence of cardiac autonomic dysfunction in these patients at an optimal cut-off value of ≤1,558 Metabolic Equivalent of Tasks- min/week.

Sudarshan Kriya Yoga improves cardiac autonomic control in patients with anxiety-depression disorders

BackgroundSeveral studies have demonstrated that adjuvant therapies as exercise and breathing training are effective in improving cardiac autonomic control (CAC) in patients with affective spectrum disorders. However, the effects of Sudarshan Kriya Yoga (SKY) on autonomic function in this population is unknown. Our objective was to test the hypothesis that SKY training improves CAC and cardiorespiratory coupling in patients with anxiety and/or depression disorders. MethodsForty-six patients with a diagnosis of anxiety and/or depression disorders (DSM-IV) were consecutively enrolled and divided in two groups: 1) conventional therapy (Control) and 2) conventional therapy associated with SKY (Treatment) for 15 days. Anxiety and depression levels were determined using quantitative questionnaires. For the assessment of CAC and cardiorespiratory coupling, cardiorespiratory traces were analyzed using monovariate and bivariate autoregressive spectral analysis, respectively. ResultsAfter 15-days, we observed a reduction of anxiety and depression levels only in Treatment group. Moreover, sympathetic modulation and CAC were significantly lower while parasympathetic modulation and cardiorespiratory coupling were significantly higher in the Treatment compared to Control group. ConclusionsIntensive breathing training using SKY approach improves anxiety and/or depressive disorders as well as CAC and cardiorespiratory coupling. These finding suggest that the SKY training may be a useful non-pharmacological intervention to improve symptoms and reduce cardiovascular risk in patients with anxiety/depression disorders.

Inspiratory muscle training in patients with diabetic autonomic neuropathy: a randomized clinical trial.

We evaluated the effects of an 8-week inspiratory muscle training (IMT, n=5) or placebo IMT (P-IMT, n=5) on maximal respiratory pressures, pulmonary function, functional capacity, and cardiac autonomic control in patients with type 2 diabetes and diabetic autonomic neuropathy (DAN). The IMT group had a greater increase in maximum inspiratory pressure as compared to P-IMT (p<0.05). The IMT improved inspiratory muscle strength in patients with DAN.

Cardiovascular autonomic control in patients undergoing left ventricular assist device (LVAD) support and pharmacologic therapy

The objective of the study is to determine cardiac autonomic control in patients undergoing assessment for and/or LVAD therapy. Heart rate variability (HRV) was measured in 17 explanted LVAD, 17 implanted LVAD and 23 NYHA III-IV classified chronic heart failure (CHF) patients and ten healthy matched controls under three conditions: supine free breathing, standing and supine controlled breathing. Five measures of HRV were assessed: mean R-R interval (mR-R), high frequency (HF) and low frequency (LF) spectral power, LF in normalised units (LFnu), and LF to HF (LF:HF) ratio. Repeat measures ANOVA showed significant (p < 0.05) differences in HRV between all three conditions within groups. Lower values were observed in CHF for LF(in log natural units) compared with explanted patients (-1.4 [95% CI -2.6 to -0.7], p = 0.04) and controls (-2.1 [-3.5 to -0.7], p = 0.001) and for LF:HF compared with implanted patients under paced breathing conditions (z = -2.7, p = 0.007) and controls in standing (z = -2.9, p = 0.004) and paced breathing conditions (z = -2.3, p = 0.02). However, no significant differences were seen between explanted, implanted and control groups under any condition. Patients implanted with an LVAD and explanted from a LVAD following myocardial recovery demonstrate a more normal dynamic response to autonomic stimuli and have a lower HRV risk profile compared to CHF patients.

A prospective, longitudinal study of the improvement of vascular function and cardiac autonomic control following renal transplantation

Uremic state is strongly associated with autonomic nervous system dysfunction and impaired endothelial vascular function. Furthermore, decreased heart rate variability (HRV) in patients with ESRD is associated with higher rates of cardiovascular events. Therefore, we studied endothelial vascular function and cardiac autonomic control in patients with ESRD before and 3 months, 12 months, and 36 months following renal transplantation (RT). Vascular function was assessed by flow mediated dilatation (FMD) and cardiac autonomic control was assessed by time‐ and frequency‐domain HRV analysis. FMD increased by 50% at one year after RT. One year following RT, time‐ and frequency‐domain HRV parameters tended to increase (e.g., RMSSD 20.7±1.9 ms before RT vs. 25.3±5.4 ms one year after RT), indicating improved autonomic cardiac control. Compared to one year following RT, HRV parameters tended to be slightly lower at 3 years following RT, but were still greater than before RT. Importantly, HRV (SDNN) correlated significantly (R=0.4, P&lt;0.05) with FMD. We conclude that renal transplantation in ESRD patients chronically improves endothelial vascular function and cardiac autonomic control. We speculate that improved endothelial vascular function contributes to reduced cardiovascular events following RT in ESRD patients. Supported by: National Institutes of Health (NHLBI K23 HL080410)

Polysomnography underestimates altered cardiac autonomic control in patients with obstructive sleep apnea

Repetitive nocturnal sympathetic activation during episodes of apnea and postapneic hyperventilation increases cardiovascular risk. The effects of hypopnea and non-apneic, non-hypopneic intervals before and after hypopnea/apnea on sympathico-vagal balance have not been assessed yet. Hypopnea and non-apneic, non-hypopneic intervals before and after hypopnea/apnea cause increased sympathetic activity when compared to normal respiration in nonREM stages 2–4. A total of 34 patients were studied using in-laboratory polysomnography including continuous ECG recording. Absolute spectral power of heart rate variability in the very low (VLF), low (LF), and high frequency (HF) bands and low frequency to high frequency power ratio (LF/HF ratio) were analyzed during apnea, hypopnea, and during the pre- and post-phases of such respiratory episodes and compared to spectral powers during normal respiration in nonREM sleep 2–4. Patients with hypopnea and/or obstructive apnea showed higher power of VLF and the LF/HF ratio in intervals of hypopnea/apnea and in non-apneic, non-hypopneic intervals before and after hypopnea/apnea compared to normal respiration in nonREM stages 2–4. The effect of sleep-disordered breathing on alteration of autonomic tone in patients with hypopnea and obstructive apnea is more severe than estimated by conventional polysomnographic assessment of apnea and hypopnea. Patients with sleep apnea show a sympathetic overdrive not only during phases of hypopnea and obstructive apnea but also in non-apnea, non-hypopnea intervals before and after hypopnea, and obstructive apnea.

Cardiac autonomic control in patients with myasthenia gravis and thymoma

To evaluate cardiac autonomic control in patients with myasthenia gravis (MG) and thymoma. The study was performed on 21 patients with MG and thymoma and the same number of matched healthy volunteers. Standard cardiovascular reflex tests according to Ewing and baroreflex sensitivity (BRS) at rest was applied. Spectral analysis of heart rate variability (HRV) at rest was assessed using a 20-minute ECG recording (normalized low- and high-frequency bands-LFnu-RRI, HFnu-RRI and LF/HF-RRI) Time-domain analysis of HRV was derived from 24-hour ECG monitoring. Overall autonomic score according to Ewing was significantly increased in patients with MG and thymoma (p<0.05), mostly due to parasympathetic dysfunction. Time-domain parameters representing the overall and long-term sympathetic activity of HRV did not differ significantly between the two groups (p>0.05), but there was a significant decrease in measures of the short-term vagal variations in HRV (p<0.01). HFnu-RRI was lower, while LFnu-RRI and LF/HF-RRI were higher in patients with MG and thymoma in comparison to healthy controls but these differences were not of statistical significance (p>0.05). BRS at rest was highly significantly reduced in patients group (p<0.01). Our results showed mainly parasympathetic cardiac impairment in patients with myasthenia gravis and thymoma. Since autonomic dysfunction may lead to cardiac conduction abnormalities and sudden death, the investigation of autonomic nervous system function in these patients may be significant in everyday clinical practice.

Efficacy of pharmacological treatment and genetic characterization in early diagnosed patients affected by long QT syndrome with impaired AV conduction

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Substituição do carvedilol pelo propranolol em pacientes com insuficiência cardíaca

Large clinical trials using the betablockers carvedilol, metoprolol, bisoprolol and nebivolol have demonstrated improvement of survival and symptoms in patients with heart failure. Despite the lack of scientific evidence, it is plausible that their beneficial effects are extensible to other betablockers.To evaluate the impact of the replacement of carvedilol for propranolol on left ventricular function, functional capacity, quality of life, pressure levels, and cardiac autonomic control in patients with heart failure.Twenty nine patients receiving optimized drug therapy including maximum tolerated doses of carvedilol were divided into two groups: replacement of carvedilol for propranolol (n = 15) and continued carvedilol (n = 14). At baseline and 6 months later, clinical and laboratorial assessments were carried out with radionuclide ventriculography, echocardiography, Minnesota questionnaire, walk test, APBM and Holter monitoring.The clinical and demographic characteristics were similar in the two groups at baseline. Individualized propranolol dose adjustment ensured a similar degree of beta-blockade, as assessed by resting heart rate and chronotropic reserve. The mean propranolol dose used was 109 +/- 43 mg/day. Only one patient presented with intolerance to propranolol, thus carvedilol was reintroduced. One death was recorded in group propranolol. Ejection fraction significantly increased in the propranolol group. No significant change was observed in the other cardiovascular variables after betablocker replacement.Our results indicate that replacement of carvedilol for propranolol in patients with heart failure is not associated with deterioration of the ejection fraction, functional capacity, quality of life, and other cardiovascular variables related to autonomic and blood pressure control., PP.0-0).

Impairment of cardiac autonomic control in patients with amyotrophic lateral sclerosis

The aim of this study was to investigate autonomic cardiac control in patients with amyotrophic lateral sclerosis (ALS). Fifty-five patients with sporadic ALS (28 female and 27 male; average age 56.00 +/- 10.34 years) were compared to 30 healthy controls (17 female and 13 male; average age 42.87 +/- 11.91 years). Patients with previous history of cardiac disease, diabetes mellitus, and impaired respiratory function were excluded from the study. Cardiovascular autonomic tests according to Ewing, power spectrum analysis of RR variability (low- and high-frequency bands - LF and HF, LF/HF index), real-time beat-to-beat ECG signal monitoring with heart rate variability analysis and baroreflex function analysis were carried out in all patients. Time-domain parameters of heart rate variability (mean RR interval, SDNN, SDANN, SDNN index, rMSSD and pNN50%) were obtained from 24-h ECG monitoring. ALS patients had a significantly higher score of sympathetic (p <0.01) and parasympathetic (p <0.001) dysfunction, as well as of the overall score of autonomic dysfunction (p <0.001). LF/HF index was significantly increased; baroreflex sensitivity and time-domain parameters of heart rate variability were highly significantly decreased in ALS patients (p <0.001). Our results demonstrated impaired cardiac autonomic control in ALS with marked parasympathetic dysfunction and sympathetic predominance.

Changes in autonomic cardiac control in patients with epilepsy after discontinuation of antiepileptic drugs: a randomized controlled withdrawal study

The aim of this study was to assess cardiac autonomic control in patients with epilepsy before and after withdrawal of antiepileptic drugs (AEDs). The study was prospective, randomized and double blinded. Spectral analysis of heart rate variability (HRV) in 24 h ECG-registration before and after withdrawal of AEDs was used to assess autonomic cardiac control. The assessment of HRV with spectral analysis was based on sinus rhythm and normal heart beats [normal to normal beat (NN)]. Thirty-nine patients had 24 h rhythms free from any ectopic beats both before and after intervention, and were included in the analysis. Significant differences were found in the withdrawal group: filtered RR intervals for all 5 min segments of the analysis; percentage of differences between adjacent filtered RR intervals that are greater than 50 ms for the whole analysis; very low frequency power; low frequency power and high frequency power. The results demonstrate that slow withdrawal of AEDs in seizure-free patients with epilepsy on drug mono-therapy resulted in an increase in both parasympathetic and sympathetic functions, indicative of increased power amongst patients following cessation of AED treatment. As low HRV has been associated with increased mortality in patients with other diseases, this increased HRV may be beneficial.

Cardiac Autonomic Control in Patients with Refractory Epilepsy before and during Vagus Nerve Stimulation Treatment: A One‐Year Follow‐up Study

To elucidate possible effect of vagus nerve stimulation (VNS) therapy on interictal heart rate (HR) variability in patients with refractory epilepsy before and after 1-year VNS treatment. A 24-hour electrocardiogram (ECG) was recorded at the baseline and after 12 months of VNS treatment in 14 patients with refractory epilepsy, and once in 28 healthy age- and sex-matched control subjects. Time and frequency domain measures, along with fractal and complexity measures of HR variability, were analyzed from the ECG recordings. The mean value of the RR interval (p=0.008), standard deviation of N-N intervals (SDNN) (p<0.001), very-low frequency (VLF) (p<0.001), low-frequency (LF) (p=0.001), and high-frequency (HF) (p=0.002) spectral components of HR variability, and the Poincaré components SD(1) (p=0.005) and SD(2) (p<0.001) of the patients with refractory epilepsy were significantly lower than those of the control subjects before VNS implantation. The nocturnal increase in HR variability usually seen in the normal population was absent in patients with refractory epilepsy. VNS had no significant effects on any of the HR-variability indexes despite a significant reduction in the frequency of seizures. HR variability was reduced, and the nocturnal increase in HR variability was not present in patients with refractory epilepsy. One-year treatment with VNS did not have a marked effect on HR variability, suggesting that impaired cardiovascular autonomic regulation is associated with the epileptic process itself rather than with recurrent seizures.

Warm-up phenomenon and cardiac autonomic control in patients with coronary artery disease

Decreased heart rate variability (HRV) and heart rate turbulence (HRT) are independent predictors of mortality after acute myocardial infarction (AMI). There are no previous studies on the relationship between warm-up phenomenon and cardiac autonomic control in stable coronary artery disease (CAD). We investigated the responses in HRV to repeated exercise induced ischemia and differences in global HRV and HRT in patients with and without adaptation to ischemia (warm-up phenomenon). Fifty male patients with CAD underwent two successive exercise tests with ambulatory electrocardiogram (ECG) recordings. HRV was evaluated using time and frequency domain measures and HRT was determined among patients with ventricular premature complexes (VPCs). The patients were divided in two groups on the basis of either positive (warm-up+) or negative (warm-up−) ischemia adaptation. Total power, ULF and VLF power and pNN50 calculated from the entire ECG recording were higher in the group demonstrating warm-up phenomenon (P < 0.05 for all). In the assessment of the four short-term stationary phases (pre-and post-test 1 and 2) total power, VLF power and pNN50 were significantly higher in the warm-up positive group already at the baseline (P < 0.05 for all). Furthermore, in the entire recordings total power, ULF and VLF power and SDNN correlated positively with the decrease in ischemic burden in the recovery phase (P ≤ 0.001 for all). No significant differences were found in HRT between the groups. Our results suggest that CAD patients demonstrating warm-up phenomenon have better cardiac autonomic control, and this correlates with the extent of ischemia adaptation. The true prognostic significance of this needs to be prospectively studied, however.

Cardiovascular haemodynamics and cardiac autonomic control in patients with subclinical and overt hyperthyroidism.

To characterize cardiac structure and function and cardiac autonomic control in patients with subclinical and overt hyperthyroidism. Thirty patients with subclinical hyperthyroidism and 30 with overt disease were selected from patients never previously treated for endocrinological disease in the outpatient clinic of our institution. Twenty normal individuals were studied as control group. Left ventricular structure and function and cardiac autonomic control were evaluated, respectively, by two-dimensional Doppler echocardiography and by 24-h Holter recording with heart rate variability analysis. Patients with overt hyperthyroidism showed greater values of left ventricular end-diastolic volume (P<0.05) and left ventricular mass (P<0.05) than patients with subclinical disease. In addition, the mean velocity of left ventricular fibre shortening (P<0.05) and left ventricular ejection fraction (P<0.05) were greater in patients with overt hyperthyroidism than in patients with subclinical disease. No difference in any of these parameters was detectable between normal subjects and patients with subclinical disease. The isovolumic relaxation period was shorter in patients with subclinical hyperthyroidism than in control individuals (P<0.05) and in patients with overt hyperthyroidism (P<0.05). As regards cardiac autonomic control, all time and frequency domain measures decreased progressively from control individuals to patients with subclinical hyperthyroidism and those with overt disease (P<0.001). Thyrotoxic patients show changes in left ventricular structure and increased echocardiographic indexes of myocardial contractility, whereas the only echocardiographic feature detectable in patients with subclinical hyperthyroidism is an increased velocity of left ventricular relaxation. Cardiac parasympathetic withdrawal is evident in patients with overt hyperthyroidism and in patients with subclinical disease.