Autonomic Imbalance In Patients Research Articles

The Autonomic Imbalance of Myocardial Ischemia during Exercise Stress Testing: Insight from Short-Term Heart Rate Variability Analysis.

Exercise stress testing (EST) has limited power in diagnosing obstructive coronary artery disease (CAD). The heart rate variability (HRV) analysis might increase the sensitivity of CAD detection. This study aimed to evaluate the correlation between short-term HRV and myocardial ischemia during EST, including the acceleration, maximum, and recovery stages of heart rate (HR). The HRV during EST from 19 healthy (RHC) subjects and 35 patients with CAD (25 patients with insignificant CAD (iCAD), and 10 patients with significant CAD (sCAD)) were compared. As a result, all HRV indices decreased at the maximum stage and no significant differences between iCAD and sCAD were found. The low-frequency power of heart rate signal (LF) of the RHC group recovered relatively quickly from the third to the sixth minutes after maximum HR, compared with that of the sCAD group. The relative changes of most HRV indices between maximum HR and recovery stage were lower in the sCAD group than in the RHC group, especially in LF, the standard deviation of all normal to normal intervals (SDNN), and the standard deviation in the long axis direction of the Poincaré plot analysis (SD2) indices (p < 0.05). The recovery slope of LF was significantly smaller in the sCAD group than in the RHC group (p = 0.02). The result suggests that monitoring short-term HRV during EST provides helpful insight into the cardiovascular autonomic imbalance in patients with significant CAD. The relative change of autonomic tone, especially the delayed sympathetic recovery, could be an additional marker for diagnosing myocardial ischemia.

Effects of resistance added on aerobic training on autonomic function in cardiac patients.

Autonomic imbalance in patients with chronic heart failure (CHF) and cardiovascular diseases (CVD) is characterized by reduced parasympathetic and enhanced sympathetic activity. Aerobic exercise improves autonomic function in patients with CHF and CVD. However, little is known about the effects of resistance training (RT) on cardiac autonomic function. Therefore, we aimed to investigate the effects of RT added on aerobic training on autonomic function in patients with CHF and CVD. The relevant clinical trials were searched in PubMed, Physiotherapy evidence Database (PEDro, Science Direct and Google Scholar databases using the following keywords, "resistance or strength training", "chronic heart failure", "coronary artery disease", "myocardial infarction", "hypertension", "cardiovascular disease", "heart rate variability (HRV)", "heart rate recovery (HRR)", "muscle sympathetic nerve activity (MSNA)", and "autonomic function". Twelve articles with 323 subjects were eligible to be evaluated. The outcome measures included HRV, HRR, and MSNA. There were seven studies on CHF, two on CAD, and three studies on hypertension. Meta-analysis of all the studies showed that combined RT and aerobic training decreased MSNA significantly in patients with CHF and CAD (mean difference: -3.796; CI: -6.779 to 0.813; p=0.013; I2 =93.5%). No study evaluated the effects of RT or combined training on HRR. We could not find sufficient data about the effects of RT alone on HRV and HRR, but the results showed that combined RT and aerobic training improved MSNA in patients with CHF and CAD, significantly. Further studies with similar methodological principles on the same patient population are needed.

Acute particulate matter exposure is associated with disturbances in heart rate complexity in patients with prior myocardial infarction

BackgroundAmbient air pollutants can increase cardiovascular mortality. One possible mechanism is the effect on the autonomic balance of the cardiovascular system. Studies on acute effects of particulate matter (PM) exposure on heart rate variability (HRV), a surrogate marker for autonomic balance, in patients with prior myocardial infarction (MI) revealed inconsistent results. MethodWe prospectively enrolled participants with acute MI. These participants received a 24-hour Holter electrocardiography examination and echocardiography six months after the index MI. Linear [standard deviation of all normal to normal intervals, standard deviation of NN intervals (SDNN), and a low-frequency to high-frequency ratio (LF/HF)] and non-linear parameters of heart rate variability [multiscale entropy (MSE)] were calculated to show autonomic balance. Data for PM2.5, PM2.5–10, and PM10, were obtained from a fixed-site station in Taiwan. Linear mixed effect models were used to estimate acute effects (within 0–3 days) of PM exposure (per 10 μg/m3) on heart rate variability. ResultsA total of 90 participants were enrolled in this study with a mean age of 58.7 (13.3) and 83 (92.2%) male participants. Traditional HRV parameters, SDNN and LF/HF, were positively correlated with two-day lagged PM2.5–10 and PM10 [adjusted beta coefficient: SDNN: 130.3 and 58.5; LH/HF: 0.32 and 0.21 (all p < or = 0.01)]. MSE slopes 1–5 were negatively correlated with same-day PM2.5–10 and PM10 (adjusted beta coefficient −0.011 (p = 0.01) and −0.005 (p = 0.02), respectively). The left ventricular ejection fraction was negatively correlated with one-day lagged PM2.5–10, and PM10 (adjusted beta coefficient −0.49 and −0.4, respectively; both p < 0.05), after adjusting for MI size. ConclusionOur results suggest that coarse PM may acutely affect cardiac autonomic balance. MSE is a sensitive marker for detecting changes in autonomic imbalance in patients with prior MI following acute PM exposure.

The presence of ectopic atrial rhythm predicts adverse cardiovascular outcomes in a large hospital-based population

Whether ectopic atrial rhythm (EAR) is a high-risk cardiovascular phenotype (eg, the manifestation of a diseased sinoatrial node) or just a benign accelerated ectopic pacemaker remains unclear. We aimed to analyze the cardiovascular outcomes and underlying mechanisms in patients with EAR. From a 12-lead electrocardiogram hospital-based electrocardiogram database, a total of 2896 adults with EAR were propensity score matched at 1:5 with 14,480 patients with sinus rhythm (SR). Patients were retrospectively followed up for cardiovascular mortality (the primary outcome) and permanent pacemaker implantation (the secondary outcome). Heart rate variability was analyzed to compare autonomic function between patients with EAR and those with SR. The prevalence of EAR was 1.13%, which increased with age. Compared with the matched patients, those with EAR had a higher risk of cardiovascular mortality (adjusted hazard ratio 1.93; 95% confidence interval 1.52-2.44; P < .0001) and permanent pacemaker implantation (adjusted hazard ratio 5.94; 95% confidence interval 3.89-9.09; P < .0001) according to the Cox proportional hazards regression model. The risk of cardiovascular mortality was similar across the subgroups on the basis of age, sex, hypertension, type 2 diabetes mellitus, congestive heart failure, myocardial infarction, stroke, and chronic kidney diseases. In patients with EAR, the low frequency/high frequency and standard deviation of the mean normal-to-normal intervals/root mean square of successive RR interval differences ratios for heart rate variability were both lower than those in patients with SR. This implied autonomic imbalance in patients with EAR. Patients with EAR have a higher risk of cardiovascular mortality and permanent pacemaker implantation, which was associated with autonomic imbalance.

Heart rate variability in chronic low back pain patients randomized to yoga or standard care.

BackgroundChronic pain can alter the autonomic balance with increased sympathetic activity reflected in altered heart rate variability (HRV). It has been proposed that yoga can be useful to correct the autonomic imbalance in patients with chronic pain who have reduced HRV.Methods and designsIn the present randomized controlled trial 62 patients with chronic low back pain associated with altered alignment of intervertebral discs (aged between 20 and 45 years, 32 males) were randomized to 2 groups. One group received yoga for 3 months while the other group carried out standard medical care based on the physician's advice. The duration was the same, i.e., 3 months. The heart rate variability and rate of respiration were assessed at baseline and at the end of 3 months.ResultsThere was a significant difference in the baseline (pre) values between groups (p = 0.008) for respiration rate which was higher in the yoga group. The changes reported below are pre-post comparisons within each group. The yoga group showed a significant (p < 0.05; repeated measures ANOVA, post-hoc analyses) decrease in the LF power of HRV, rate of respiration and a significant increase in the HF power of HRV and in the pNN50.ConclusionThe results suggest that yoga practice can shift the autonomic balance towards vagal dominance in patients with chronic low back pain associated with altered alignment of intervertebral discs.Trial registrationThe study is registered with the Clinical Trials Registry of India (CTRI/2012/11/003094) and can be accessed at.

Autonomic Dysfunction Correlates with Clinical and Inflammatory Activity in Patients with Crohn's Disease.

Autonomic dysfunction has been implicated in Crohn's disease (CD). We aimed to investigate heart rate variability (HRV) as a marker of possible autonomic imbalance in patients with CD. Thirty patients with CD and 30 age- and gender-matched healthy controls were enrolled in a prospective cohort study and underwent HRV study. Anxiety level was scored using the STAI questionnaire and CD clinical activity was assessed by Harvey-Bradshaw index. Blood tests including inflammatory markers were obtained for all participants. CD subjects had lower mean blood pressure (85.51 ± 11.07 mm Hg, 91.51 ± 6.99, P = 0.015) and albumin and significantly higher CRP and IL-6 compared with controls (P < 0.002 for all comparisons). Mean HRV values of very low-frequency power and low-frequency power components were significantly lower among CD subjects (P = 0.038 and 0.027, respectively), implying a predominant sympathetic tone. Anxiety level scores were significantly higher among patients with CD for both state anxiety (P = 0.001) and trait anxiety (P < 0.0001). However, patients with active disease had similar anxiety scores as patients in remission, yet had a significantly lower BMI, lower albumin level, and higher CRP and IL-6 levels (P < 0.05 for all comparisons). Moreover, despite similar anxiety scores, patients with active disease had higher pulse rate (P = 0.02) and lower HRV indexes, which correlated with albumin levels(r = 0.7, P = 0.001). Although patients with CD have higher anxiety levels compared with controls, they exhibit depressed HRV independent of this anxiety state and in direct correlation with disease activity and inflammatory markers. These observations suggest an inherent imbalance of autonomic function associated with active inflammation.

Особенности интра- и экстракраниального кровотока, структурно-геометрическая и функциональная перестройка сердца и состояние вегетативной нервной системы у больных гипертонической болезнью II стадии в зависимости от статуса курильщика

Систематическое курение табака является серьезной угрозой для здоровья населения, особенно для лиц с повышенным риском сердечно-сосудистых заболеваний. Остаются нерешенными вопросы, в какой степени табакокурение влияет на прогрессирование артериальной гипертензии, нарушение вегетативного баланса, мозговой кровоток, поражение органов-мишеней.Цель. Анализ особенностей состояния мозгового кровотока, структурно-геометрической и функциональной перестройки сердца, нарушений вегетативного баланса у больных гипертонической болезнью (ГБ) ІІ стадии.Материал и методы. Обследовано 100 пациентов: 53 мужчины и 47 женщин. Средний возраст пациентов составил 52,51 ± 1,46 года. В зависимости от статуса курения (не менее 10 лет) все пациенты были разделены на 2 группы: в группу курильщиков включено 30 пациентов, в группу некурящих — 70. Всем больным проведено общеклиническое обследование с измерением массы тела и роста, с расчетом индекса массы тела, офисное измерение артериального давления (АД) и частоты сердечных сокращений, лабораторные исследования, суточное мониторирование АД, ультразвуковое исследование экстра- и интракраниальных артерий шеи и головы, определялась вариабельность сердечного ритма, выполнялась трансторакальная эхокардиоскопия. Результаты. У больных ГБ, имеющих статус курильщика, выявлено статистически достоверное увеличение мощности спектра в диапазоне низких частот на 16,5 % (р = 0,04), снижение мощности спектра в диапазоне высоких частот на 18,2 % (р = 0,04), увеличение симпатовагального индекса на 70,0 % (р = 0,01), повышение среднесуточного систолического АД (САД) на 6,5 % (р = 0,04) и среднесуточного диастолического АД (ДАД) на 7,9 % (р = 0,04), размера левого предсердия в диастолу на 8,1 % (р = 0,014), в систолу на 10,8 % (р = 0,026), толщины задней стенки левого желудочка (ЛЖ) сердца на 6,1 % (р = 0,028), толщины межжелудочковой перегородки в диастолу на 11,6 % (р = 0,004), в систолу на 10,7 % (р = 0,034), индекса массы миокарда ЛЖ на 12,2 % (р = 0,034), диастолического внутримио-кардиального напряжения на 13,9 % (р = 0,025), удлинение периода изометрического расслабления на 33,3 % (р = 0,026), индекса сосудистого сопротивления в русле правой общей сонной артерии (ОСА) на 3,3 % (р = 0,033), в русле правой средней мозговой артерии (СМА) на 8,5 % (р = 0,05), в бассейне левой СМА на 7,1 % (р = 0,042), превышение показателя «резерв вазоконстрикции» в 4,63 раза (р = 0,029) в бассейне левой внутренней сонной артерии (ВСА) и в 3,01 раза (р = 0,031) — в русле правой ВСА. Получено достоверное повышение у женщин-курильщиц по сравнению с мужчинами-курильщиками индекса сопротивления в ВСА справа на 10,8 % (0,65 ± 0,02 у.е. против 0,58 ± 0,01 у.е.; р = 0,03) и максимальной линейной скорости кровотока в ВСА слева на 22,0 % (2,88 ± 0,08 см/с против 2,36 ± 0,04 см/с; р = 0,05). При этом у женщин-курильщиц наблюдались достоверно меньшие значения систолодиастолического индекса в русле ОСА справа на 8,7 % (3,55 ± 0,19 у.е. против 3,86 ± 0,16 у.е.; р = 0,027) и индекса сопротивления в русле левой СМА на 4,9 %, чем у мужчин-курильщиков (0,450 ± 0,034 у.е. против 0,472 ± 0,024 у.е.; р = 0,027).Выводы. Курение у гипертоников ассоциируется с повышением активности симпатического и угнетением парасимпатического звеньев вегетативной нервной системы. Курильщики, страдающие ГБ, имеют достоверно более высокие цифры среднесуточного САД на 6,5 % (р = 0,04), среднесуточного ДАД на 7,9 % (р = 0,04) по сравнению с некурящими больными с ГБ. Модулирующее влияние курения на процессы патологического ремоделирования сердца у гипертоников проявляется в увеличении систолического и диастолического размеров левого предсердия, толщины стенок и массы миокарда левого желудочка, без расширения полостей сердца, при этом наблюдается увеличение диастолического внутримиокардиального напряжения левого желудочка. Структурная перестройка сердца у гипертоников под влиянием табакокурения создает условия для снижения активной релаксации и изменения диастолического наполнения левого желудочка: увеличения вклада позднего наполнения и удлинения времени изометрического расслабления. Нарушения мозгового кровотока у больных гипертонической болезнью, имеющих статус курильщика, по сравнению с некурящими гипертониками характеризуются более выраженным спазмом артерий каротидного бассейна, о чем свидетельствует повышение индексов сосудистого сопротивления и показателя «резерв вазоконстрикции» в общих сонных и средних мозговых артериях у курильщиков. Показатели кровотока в вертебробазилярном бассейне у курящих и некурящих гипертоников достоверно не различаются. Гендерные различия показателей допплерографии магистральных артерий шеи и головы у больных гипертонической болезнью, имеющих статус курильщика, характеризуются более высоким сосудистым сопротивлением в общих и внутренних сонных артериях у женщин, в средних мозговых артериях у мужчин.

OP-167 Autonomic Imbalance in Patients with Small Thoracic Aortic Aneurysms: A Study of Pupillomotor Function

OP-167 Autonomic Imbalance in Patients with Small Thoracic Aortic Aneurysms: A Study of Pupillomotor Function

Role of exercise training on autonomic changes and inflammatory profile induced by myocardial infarction.

The cardiovascular autonomic imbalance in patients after myocardial infarction (MI) provides a significant increase in mortality rate, and seems to precede metabolic, hormonal, and immunological changes. Moreover, the reduction in the parasympathetic function has been associated with inflammatory response in different pathological conditions. Over the years, most of the studies have indicated the exercise training (ET) as an important nonpharmacological tool in the management of autonomic dysfunction and reduction in inflammatory profile after a myocardial infarction. In this work, we reviewed the effects of ET on autonomic imbalance after MI, and its consequences, particularly, in the post-MI inflammatory profile. Clinical and experimental evidence regarding relationship between alterations in autonomic regulation and local or systemic inflammation response after MI were also discussed.

Dynamic assessment and overnight evaluation on autonomic imbalance in patients with sleep apnea via volatility clustering of descending (or ascending) heartbeat intervals

It is known that sleep apnea (SA) constitutes a major social problem because of its emerging association with cardiovascular morbidity [1–3], where an estimated prevalence of 30% to 50% among patients with coronary heart disease and 50% among hypertensive patients. Although the pathogenic effects of SA on cardiovascular diseases are complex, it is believed that autonomic dysregulation should be involved [4]. Abundant evidences link the activation of sympathetic nervous system to cardiovascular outcomes of SA patients [5].

Diabetic Autonomic Imbalance and Glycemic Variability

Diabetic autonomic neural imbalance is a severe complication of long-term diabetes patients and may progress to diabetic autonomic neuropathy (DAN). The prevalence of DAN is reported to be between 20 and 70%, depending on the studies. The pathogenesis of DAN remains unresolved. However, emerging evidence suggests that glycemic variability (GV) may be associated with autonomic imbalance in patients with both type 1 and type 2 diabetes. As symptoms are initially weak and uncharacteristic, the condition often remains undiagnosed until late manifestations present themselves. Predominant symptoms may include nausea, vomiting, gastroparesis, involuntary diarrhea, postural hypotension, voiding difficulties, and sexual dysfunction. Analyzing the patterns of heart rate variability carries the potential for detection of autonomic imbalance in the subclinical and asymptomatic stages. In this context, GV may affect the sympathovagal balance by increasing oxidative stress and proinflammatory cytokines. Establishing a GV risk profile could therefore be important in determining risk factors in diabetes patients. This review addresses the issues above and in particular the possible association between diabetic autonomic imbalance and GV.

Usefulness of Pet Ownership as a Modulator of Cardiac Autonomic Imbalance in Patients With Diabetes Mellitus, Hypertension, and/or Hyperlipidemia

Among patients with coronary artery disease, pet owners exhibit a greater 1-year survival rate than nonowners. Lifestyle-related diseases are well-known risk factors for coronary artery disease and induce imbalances in autonomic nervous activity. The purpose of the present study was to determine whether pet ownership modulates cardiac autonomic nervous activity imbalance in patients with lifestyle-related diseases such as diabetes mellitus, hypertension, and hyperlipidemia. A total of 191 patients (mean age 69 ± 8 years) were interviewed about their pet ownership status and were classified into pet owner and nonowner groups. After recording a 24-hour Holter electrocardiogram for heart rate variability analysis, frequency-domain and nonlinear-domain analyses were performed to determine the high-frequency (HF) and low-frequency (LF) components, LF/HF ratio, and entropy. The heart rate variability parameters were assessed for 24 hours, during the day (8.00 A.M. to 5.00 P.M.), and during the night (0:00 A.M. to 6.00 A.M.), and compared between the 2 groups. To evaluate the potential predictive factors for cardiac autonomic imbalance, univariate and multivariate analyses of HF and LF/HF were conducted for potential confounding variables. The pet owner group exhibited significantly greater HF(24h), HF(day), HF(night), entropy(24h), entropy(day), and entropy(night) and significantly lower LF/HF(24h) and LF/HF(night) compared to the nonowner group. On multivariate analysis, pet ownership was independently and positively associated with HF(24h,) HF(day), and HF(night) and inversely associated with LF/HF(24h) and LF/HF(night). In conclusion, these results suggest that pet ownership is an independent modulator of cardiac autonomic imbalance in patients with lifestyle-related diseases.

Blood Pressure Variability as Sign of Autonomic Imbalance in Patients with Idiopathic Dilated Cardiomyopathy

The problem of identifying idiopathic dilated cardiomyopathy (IDC) patients who are at risk of sudden death is still unsolved. The presence of autonomic imbalance in patients with IDC might predict sudden death and tachyarrhythmic events. The aim of this study was to analyze the suitability of blood pressure variability (BPV) compared to heart rate variability (HRV) for noninvasive risk stratification in IDC patients. Continuous noninvasive blood pressure and high-resolution electrocardiogram were recorded from 91 IDC patients for 30 minutes. During a median follow-up period of 28 months (range: [17-38] months), 14 patients died due to sudden death or necessary resuscitation due to a life-threatening arrhythmia. HRV and BPV analyses were performed in time domain, frequency domain, and nonlinear dynamics. Using the Mann-Whitney U test and Cox regression, we estimated the accuracy of clinical and nonclinical parameters in discriminating high-risk from low-risk patients. Dynamics of blood pressure regulation was significantly changed in high-risk patients, indicating an increased BPV. BPV indexes from nonlinear symbolic dynamics revealed significant univariate (sensitivity: 85.7%; specificity 77.9%; area under receiver-operator characteristics [ROC] curve: 87.8%) differences. In an optimum multivariate set consisting of two clinical indexes (left ventricular end-diastolic diameter, New York Heart Association) and one nonlinear index (symbolic dynamics), highly significant differences between low- and high-risk IDC groups were estimated (sensitivity of 92.9%, specificity of 86.5%, and area under ROC curve of 95.3%). Diastolic BPV indexes, especially those from symbolic dynamics, appear to be useful for risk stratification of sudden death in patients with IDC.

Physiological responses to low-force work and psychosocial stress in women with chronic trapezius myalgia

BackgroundRepetitive and stressful work tasks have been linked to the development of pain in the trapezius muscle, although the underlying mechanisms still remain unclear. In earlier studies, it has been hypothesized that chronic muscle pain conditions are associated with imbalance in the autonomic nervous system, predominantly expressed as an increased sympathetic activity. This study investigates whether women with chronic trapezius myalgia show higher muscle activity and increased sympathetic tone at baseline and during repetitive low-force work and psychosocial stress, compared with pain-free controls.MethodsEighteen women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON) were studied during baseline rest, 100 min of repetitive low-force work, 20 min of psychosocial stress (Trier Social Stress Test, TSST), and 80 min recovery. The subjects rated their pain intensity, stress and energy level every 20 min throughout the experiment. Muscle activity was measured by surface electromyography in the trapezius muscle (EMGtrap) and deltoid muscle (EMGdelt). Autonomic reactivity was measured through heart rate (HR), skin conductance (SCL), blood pressure (MAP) and respiration rate (Resp).ResultsAt baseline, EMGtrap, stress ratings, and HR were higher in MYA than in CON. Energy ratings, EMGdelt, SCL, MAP and Resp were, however, similar in the two groups. Significant main group effects were found for pain intensity, stress ratings and EMGtrap. Deltoid muscle activity and autonomic responses were almost identical in MYA and CON during work, stress and recovery. In MYA only, pain intensity and stress ratings increased towards the end of the repetitive work.ConclusionWe found increased muscle activity during uninstructed rest in the painful muscle of a group of women with trapezius myalgia. The present study could not confirm the hypothesis that chronic trapezius myalgia is associated with increased sympathetic activity. The suggestion of autonomic imbalance in patients with chronic local or regional musculoskeletal pain needs to be further investigated.

Autonomic imbalance in patients with takotsubo cardiomyopathy: cause or association?

Sir, In a recent paper, Akashi et al. 1 examined cardiac autonomic functions in patients with reversible takotsubo cardiomyopathy (TC), and suggested that this disorder might be caused by neurogenic stunning of the myocardium due to acute autonomic dysfunction. While these findings are very interesting, and may provide useful insight into the pathogenesis of this poorly understood disorder, certain ethical issues and suggested interpretations of the study deserve attention. In their study, the diagnosis of TC was made based upon acute-onset myocardial-infarction-like symptoms and EKG changes, elevated cardiac enzymes in most patients, normal coronaries on coronary angiography and typical apical ballooning seen on left ventriculogram and/or echocardiography. All their patients fulfil the joint European Society of Cardiology/American College of Cardiology committee diagnostic criteria for acute myocardial infarction (AMI),2 which is not only much more common …

A polymorphism of the endothelial nitric oxide synthase promoter is associated with an increase in autonomic imbalance in patients with congestive heart failure

In addition to its well-recognized role in the regulation of vascular tone, nitric oxide modulates sympathetic and parasympathetic nervous system activities. Abnormalities of both autonomic control and nitric oxide synthase activity are known to occur in patients with congestive heart failure. Recently, a polymorphism of the promoter of the endothelial nitric oxide synthase (eNOS) gene has been associated with a reduction of eNOS activity. This study tested the hypothesis that patients with congestive heart failure who are homozygous for this polymorphism will have a more advanced imbalance of autonomic activity. Patients who have congestive heart failure were tested for the presence of an eNOS promoter polymorphism (thymidine to cytosine transition [T(-786)C]). Spectral analysis of heart rate variability was performed to quantify sympathetic and parasympathetic autonomic activity, which were compared between subjects homozygous for the polymorphism and all other subjects. Patients homozygous for the polymorphism of the eNOS promoter had a greater autonomic imbalance as reflected by significant differences in high- and low-frequency heart rate variability. These differences in autonomic function were noted in the absence of intergroup differences in patterns of respiratory variability, demographic features, and despite a higher mean ejection fraction in patients homozygous for the polymorphism. Patients with congestive heart failure who are homozygous for this polymorphism of the eNOS promoter were found to have a more advanced autonomic imbalance. This polymorphism may serve as a marker for patients at increased risk for sudden death and more rapid progression of disease.

Enhanced central hypercapnic chemosensitivity is related to autonomic imbalance in patients with heart failure

Purpose: The role of central hypercapnic chemosensitivity in autonomic imbalance remains obscure in patients with heart failure. The purpose of this study is to elucidate whether enhanced central hypercapnic chemosensitivity is related to sympathetic activation and parasympathetic withdrawal in this syndrome. Methods: In 40 patients with chronic heart failure, the central hypercapnic chemosensitivity and plasma norepinephrine were measured in the supine resting position. A stationary 6-minute period tracings of blood pressure and electrocardiogram served for measurements of high-frequency(HF) components of heart rate variability and the α-index, the ratio of RR interval and systolic blood pressure variability. Results: The patients with increased sympathetic tone showed a greater chemosensitivity and a resultant augmentation in exercise ventilation. In contrast, the chemosensitivity had an inverse relationship with HF power of heart rate variability (r = −0.38, p < 0.05) and the α-index (r = −0.41, p < 0.01). There were no significant correlations between the hypercapnic chemosensitivity and left ventricular function and between the chemosensitivity and exercise capacity. Conclusions: The enhanced central hypercapnic chemoreflex would potentially underlie autonomic imbalance in patients with chronic heart failure.

Five-minute recording of heart rate variability in severe chronic heart failure: Correlates with right ventricular function and prognostic implications

Background In advanced chronic heart failure (CHF), correlation between heart rate variability (HRV) and parameters of disease severity is still unclear. A reduced HRV has been related to left but not to right ventricular function parameters. Moreover, the prognostic role of spectral measures is not fully defined. We sought to assess HRV by using a short electrocardiographic recording in ambulatory patients with severe CHF to investigate the relation of HRV with clinical neurohormonal and hemodynamic parameters and to determine its predictive prognostic power. Methods and Results HRV was obtained from 5-minute electrocardiographic recordings in 75 ambulatory patients with CHF referred for heart transplantation screening. Standard frequency-domain parameters (total power, low-frequency power, and high-frequency power) were calculated. Prognostic value of these autonomic markers and their correlation with clinical and instrumental parameters were also assessed. A low low-frequency/high-frequency ratio was an independent predictor of cardiac events (P =.015). No correlation was found between New York Heart Association class and HRV, whereas significant correlations were identified between norepinephrine plasma levels, several hemodynamic parameters, and spectral measures (P ≤.03). A reduced HRV, particularly a low-frequency power reduction (P =.000), was highly related to indexes of right ventricular dysfunction. Conclusions The current data indicate that spectral analysis of HRV, calculated from short electrocardiographic recordings, may represent a simple but effective means contributing to risk stratification of patients with severe CHF. Autonomic information obtained from this analysis suggests that right ventricular dysfunction may be a critical element determining autonomic imbalance in patients with severe CHF. (Am Heart J 2000;139:1088-95.)

Autonomic Imbalance in Patients with Inappropriate Sinus Tachycardia

Autonomic Imbalance in Patients with Inappropriate Sinus Tachycardia

749-2 Autonomic Imbalance in Patients with Inappropriate Sinus Tachycardia

Mechanisms responsible for inappropriate sinus tachycardia (IST) may include an intrinsic defect in the sinus node, autonomic imbalances, or both. To disclose the existence of spontaneous autonomic abnormalities, we analyzed heart rate variability (HRV) in 24-hour ECG recordings in 6 ambulatory adult pts with IST (defined as 24-hr average heart rate ≥ 95 bpm) and in 6 ageand sex-matched normal controls. All subjects were free of heart disease, diabetes, and autonomic disfunction. Mean average HR was 98 ± 2.6 bpm in pts with IST and 69.6 ± 7 bpm in controls. Percent of difference between adjacent RR intervals greater than 50 msec (pNN50) was 2.63 in pts and 23.9 in controls (p &lt; 0.001). Standard deviation of RR intervals (SDNN), root mean square of successive differences (RMSSD), and standard deviation of 5-minute RR intervals (SDANN)forthe 24 hour period were significantly lower in pts than in controls for both day- and night-times (table). SDNN RMSSD SDANN Day Night Day Night Day Night Patients 47.59 51.22 19.04 23.4 62.3 30.7 Controls 98.1 97.78 41.9 58.55 50.55 29.9 P value &lt; 0.001 &lt; 0.001 &lt; 0.001 &lt; 0.001 &lt; 0.001 0.01 Hourly variation for RMSDDs is plotted in the figure. Low and high frequency (freq) power were estimated at 10-min intervals throughout the 24 hour-period. Average Ln of low freq power was 10.26 in pts with IST and 11.27 in controls (p = 0.09). Average Ln of high freq power was 9.81 in pts and 11.31 in controls (p = 0.002). 1) HRV is markedly decreased in pts with IST; 2) This seems to be related to an abnormally low parasympathetic tone; 3) The long-term prognosis of pts with IST deserves further investigation.