Effects of pharmacological adrenergic and vagal modulation on fractal heart rate dynamics

Tulppo, Mikko P.; Mäkikallio, Timo H.; Seppänen, Tapio; Shoemaker, J. Kevin; Tutungi, Elli; Hughson, Richard L.; Huikuri, Heikki V.

doi:10.1046/j.1365-2281.2001.00344.x

Cited by 110 publications

(88 citation statements)

References 33 publications

(42 reference statements)

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“…Interestingly, it also increases with atropine and decreases with vagal activation (28,31). Because vagal activity is generally reduced in hemodialysis patients (15)(16)(17), those with and without sympathetic overactivity might be better discriminated by scaling exponent a 1 than by the measures simply reflecting vagal modulation.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear Measures of Heart Rate Variability and Mortality Risk in Hemodialysis Patients

Suzuki

Aoyama

Tanaka

et al. 2012

Clinical Journal of the American Society of Nephrology

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SummaryBackground and objectives Nonlinear measures of heart rate variability (HRV) have gained recent interest as powerful risk predictors in various clinical settings. This study examined whether they improve risk stratification in hemodialysis patients.Design, setting, participants, & measurements To assess heart rate turbulence, deceleration capacity, fractal scaling exponent (a 1 ), and other conventional HRV measures, 281 hemodialysis patients underwent 24-hour electrocardiography between January 2002 and May 2004 and were subsequently followed up.Results During a median 87-month follow-up, 77 patients (27%) died. Age, left ventricular ejection fraction, serum albumin, C-reactive protein, and calcium 3 phosphate independently predicted mortality. Whereas all nonlinear HRV measures predicted mortality, only decreased scaling exponent a 1 remained significant after adjusting for clinical risk factors (hazard ratio per a 0.25 decrement, 1.46; 95% confidence interval [95% CI], 1.16-1.85). The inclusion of a 1 into a prediction model composed of clinical risk factors increased the C statistic from 0.84 to 0.87 (P=0.03), with 50.8% (95% CI, 20.2-83.7) continuous net reclassification improvement for 5-year mortality. The predictive power of a 1 showed an interaction with age (P=0.02) and was particularly strong in patients aged ,70 years (n=208; hazard ratio, 1.87; 95% CI, 1.38-2.53), among whom a 1 increased the C statistic from 0.85 to 0.89 (P=0.01), with a 93.1% (95% CI, 59.3-142.0) continuous net reclassification improvement.Conclusions Scaling exponent a 1 that reflects fractal organization of short-term HRV improves risk stratification for mortality when added to the prediction model by conventional risk factors in hemodialysis patients, particularly those aged ,70 years.

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Section: Discussionmentioning

confidence: 99%

Nonlinear Measures of Heart Rate Variability and Mortality Risk in Hemodialysis Patients

Suzuki

Aoyama

Tanaka

et al. 2012

Clinical Journal of the American Society of Nephrology

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“…The high-frequency spectral component of heart rate variability and SD1 analyzed from Poincaré plots have been previously shown to reflect the cardiac vagal outflow (29 -31). Both high-frequency oscillations of heart rate and short-term heart rate oscillations (SD1) measured from return plots are almost absent after vagal blockade (30,31). The latter index (SD1) was used in this study in addition to spectral analysis because it is less sensitive to trends in heart rate itself when compared with analysis of the high-frequency power spectral component (26).…”

Section: Discussionmentioning

confidence: 99%

Effects of Sustained Insulin-Induced Hypoglycemia on Cardiovascular Autonomic Regulation in Type 1 Diabetes

et al. 2005

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Effects of hypoglycemia on cardiac autonomic regulation may contribute to the occurrence of adverse cardiac events. This study assessed the effects of sustained hyperinsulinemic hypoglycemia on cardiovascular autonomic regulation in type 1 diabetic patients and their nondiabetic counterparts. The study consisted of 16 type 1 diabetic patients and 8 age-matched healthy control subjects who underwent euglycemic and hypoglycemic clamp procedures in a random order. Heart rate variability was measured from continuous electrocardiogram recordings by time and frequency domain methods, along with Poincaré plot analysis during both a hyperinsulinemic-euglycemic and hypoglycemic clamp at three different glucose levels (4.5-5.5, 3.0 -3.5, and 2.0 -2.5 mmol/l). Controlled hypoglycemia resulted in an increase of supine heart rate in both the diabetic patients (from 72 ؎ 9 to 80 ؎ 11 bpm, P < 0.01) and the control subjects (from 59 ؎ 5 to 65 ؎ 5 bpm, P < 0.05) and progressive reductions of the high-frequency spectral component and beat-to-beat heart rate variability (SD1; P < 0.05 in the diabetic patients and P < 0.01 in control subjects). No significant changes in heart rate variability occurred during the euglycemic clamp. We conclude that hypoglycemia results in a reduction of cardiac vagal outflow in both diabetic and nondiabetic subjects. Altered autonomic regulation may contribute to the occurrence of cardiac events during hypoglycemia. Diabetes 54:744 -750, 2005 D uring hypoglycemia the release of counterregulatory hormones serves to maintain blood glucose homeostasis. The response of catecholamines is normally not important, but it becomes critical when the response of glucagon is deficient, as in type 1 diabetic patients, who are largely dependent on epinephrine to correct and prevent hypoglycemia (1,2).Many studies have documented impaired secretory responses of epinephrine to plasma glucose decrements in type 1 diabetic patients (1,3). This response impairs gradually over several years after the diagnosis of diabetes. In diabetic patients, the blunted response of counterregulatory hormones may result in a loss of the ability to recognize developing hypoglycemia (1,3,4). Recurrent iatrogenic hypoglycemia also elevates the glycemic thresholds for symptoms and for the activation of the glucose counterregulation system (3-9). It has also been hypothesized that hypoglycemia may play a role in the "dead in bed" syndrome, i.e., the sudden nocturnal death of young individuals with type 1 diabetes (10,11).Heart rate variability has been increasingly used to assess autonomic function in various physiological and pathological settings, including the assessment of autonomic dysfunction in diabetic patients (12-18). There are some reports on changes in heart rate variability during hypoglycemia among healthy subjects (19 -20), but less is known about hypoglycemia-induced changes in cardiac autonomic regulation in diabetic patients. The present study was designed to assess and compare changes in heart rate and heart rate variabi...

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“…Frequency‐domain indices of BP variability were the LF power of diastolic BP, reported to reflect sympathetically mediated vasomotor oscillations generally assumed to be induced by baroreflex resonance10, 11; the very‐low frequency power of diastolic BP that quantifies long‐term fluctuations mainly of vasomotor origin; and the sensitivity of baroreflex control of HR estimated by the transfer function method over the LF (BRS LF) and HF (BRS HF) bands. Additionally, we calculated the number of PI increases per minute larger than 50 ms (NN50+ , time‐domain index of cardiac parasympathetic modulation under the hypothesis that bursts of vagal outflow on the sinus node produce PI lengthening of more than 50 ms)12; and the short‐term scale coefficient α 1 through detrended fluctuation analysis of PI, which is a complexity‐domain index of cardiac sympatho/vagal balance 13, 14…”

Section: Methodsmentioning

confidence: 99%

Hemodynamic and Autonomic Response to Different Salt Intakes in Normotensive Individuals

Castiglioni

Parati

Lazzeroni

et al. 2016

JAHA

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BackgroundEven if sodium sensitivity represents a risk factor at any blood pressure (BP) level, limited evidence is available that it may influence cardiovascular control in normotensives, particularly in white individuals. Therefore, the aim of the study was to investigate whether sodium sensitivity alters hemodynamic or autonomic responses to salt in normotensives.Methods and ResultsWe evaluated the Sodium‐Sensitivity Index (SS‐Index) in 71 white normotensives after 5 days of high‐ and low‐sodium diets. We measured BP continuously at the end of each period, estimating hemodynamic indices from BP waveform analysis, and autonomic indices from heart rate (HR) and BP variability. According to the SS‐Index distribution, we defined 1 sodium‐sensitive group (SS, with SS‐Index >15 mm Hg/[mmol·day]), 1 sodium‐resistant group, (unresponsive to sodium load with −15≤ SS‐Index ≤+15), and 1 inverse sodium‐sensitive group, responsive to sodium by decreasing BP, with SS‐Index <−15). We compared the effects of the diets among groups, and correlated autonomic/hemodynamic indices with the SS‐Index. After sodium loading, a significant decrease in systemic peripheral resistances, HR, spectral indices of BP modulation, and a significant increase of indices of HR vagal modulation were found in the inverse sodium‐sensitive group but not in SS normotensives. Moreover, the highest SS‐Indices were associated with the lesser vagal HR decelerations.ConclusionsOur data suggest that salt sensitivity in white normotensive individuals is associated with impaired vasodilation and altered autonomic response to dietary salt. Such dysfunction may critically contribute to induce a BP response to dietary salt.

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Effects of pharmacological adrenergic and vagal modulation on fractal heart rate dynamics

Cited by 110 publications

References 33 publications

Nonlinear Measures of Heart Rate Variability and Mortality Risk in Hemodialysis Patients

Nonlinear Measures of Heart Rate Variability and Mortality Risk in Hemodialysis Patients

Effects of Sustained Insulin-Induced Hypoglycemia on Cardiovascular Autonomic Regulation in Type 1 Diabetes

Hemodynamic and Autonomic Response to Different Salt Intakes in Normotensive Individuals

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