Association between Exercise-Induced Hypertension and Heart Rate Variability, Arterial Stiffness

As reports show cardiovascular (CV) risks in first-degree relatives (FDR) of type2 diabetics, and autonomic imbalance predisposing to CV risks, in the present study we have assessed the contribution of sympathovagal imbalance (SVI) to CV risks in these subjects. Body mass index (BMI), waist-to-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP), and spectral indices of heart rate variability (HRV) were reordered and analyzed in FDR of type2 diabetics (study group, n=293) and in subjects with no family history of diabetes (control group, n=405). The ratio of low-frequency (LF) to high-frequency (HF) power of HRV (LF-HF), a sensitive marker of SVI, was significantly increased (P<0.001) in the study group compared with the control group. The SVI in the study group was due to concomitant sympathetic activation (increased LF) and vagal inhibition (decreased HF). In the study group, the LF-HF ratio was significantly correlated with BMI, WHR, BHR, BP and RPP. Multiple regression analysis showed an independent contribution of LF-HF to hypertension status (P=0.000), and bivariate logistic regression showed significant prediction (odds ratio 2.16, confidence interval 1.130-5.115) of LF-HF to increased RPP, the marker of CV risk, in the study group. Sympathovagal imbalance in the form of increased sympathetic and decreased parasympathetic activity is present in FDR of type2 diabetics. Increased resting heart rate, elevated hypertension status, decreased HRV and increased RPP in these subjects make them vulnerable to CV risks. SVI in these subjects contributes to CV risks independent of the degree of adiposity.

Background — Although brachial-ankle pulse wave velocity is a widely used index of arterial stiffness, there are several limitations of this method. The actual length of an artery used for measuring pulse wave velocity is estimated based on an anatomical correction value, and brachial-ankle pulse wave velocity is directly affected by systemic blood pressure or vascular occlusion. Thus, the aim of this study was to determine whether aortic wall strain rate as measured by tissue Doppler imaging is a more useful modality for evaluating regional arterial stiffness than brachial-ankle pulse wave velocity.Methods — Seventy-two patients (18 to 78 years) with normal cardiac function and without large vessel complications were enrolled in this study.Results — A significant positive correlation was found between brachial-ankle pulse wave velocity and age, and brachial-ankle pulse wave velocity increased with age (r = 0.64, P< 0.0001).A significant negative correlation was found between strain rate and age, and strain rate decreased with age (r = –0.44, P < 0.05). A significant correlation was also found between brachial-ankle pulse wave velocity and systolic blood pressure (r = 0.45, P < 0.02), but not between strain rate and systolic blood pressure. There was no significant difference in brachial-ankle pulse wave velocity between hyperlipidaemic and normolipidaemic subjects. However, strain rate was lower in hyperlipidaemic than in normolipidaemic subjects (P < 0.05).Conclusion — Strain rate on the ascending aortic wall is a novel and more accurate index of regional arterial stiffness than brachial-ankle pulse wave velocity.

Many patients with severe obstructive sleep apnea (OSA) do not complain of excessive daytime sleepiness (EDS), possibly due to increased sympathetic nervous activity (SNA) and accompanying heightened alertness. We hypothesized that in patients with OSA, those without subjective EDS (Epworth Sleepiness Scale, ESS score < 11) would have higher very low frequency (VLF) heart rate variability (HRV) during sleep, reflecting greater sympathetic heart rate modulation than patients with an ESS score ≥ 11. Patients with severe OSA (AHI ≥ 30: 26 with and 65 without heart failure) were divided into those with and without EDS. Heart rate (HR) signals were acquired in stage 2 sleep during periods of recurrent apneas and hypopneas and submitted to coarse graining spectral analysis, which extracts harmonic, neurally mediated contributions to HRV from total spectral power. Because the apnea-hyperpnea cycle entrains muscle SNA at VLF (0 to 0.04 Hz), VLF power was our principal between-group comparison. Subjects without EDS had higher harmonic VLF power (944 ± 839 vs 447 ± 461 msec(2), p = 0.003) than those with EDS, irrespective of the presence or absence of heart failure (1218 ± 944 vs 426 ± 299 msec(2), p = 0.043, and 1029 ± 873 vs 503 ± 533 msec(2), p = 0.003, respectively). ESS scores correlated inversely with VLF power in all (r = -0.294, p = 0.005) and in heart failure subjects (r = -0.468, p = 0.016). Patients with severe OSA but without EDS have higher VLF-HRV than those with EDS. This finding suggests that patients with severe OSA but without EDS have greater sympathetic modulation of HRV than those with EDS that may reflect elevated adrenergically mediated alertness. Taranto Montemurro L; Floras JS; Picton P; Kasai T; Alshaer H; Gabriel JM; Bradley TD. Relationship of heart rate variability to sleepiness in patients with obstructive sleep apnea with and without heart failure.

The relationship between arterial stiffness and cardiorespiratory fitness in long-distance runners with exercise-induced hypertension has not been established. We assessed the relationship among exercise-induced hypertension, arterial stiffness, and cardiorespiratory fitness in long-distance runners. Middle-aged men between 40 and 60 years of age were assigned to the following groups: normal blood pressure (N.=17), exercise-induced hypertension (N.=39), and undiagnosed complex hypertension (N.=10) using the graded exercise test. Arterial stiffness was evaluated with carotid-femoral pulse wave velocity and augmentation index. The carotid-femoral pulse wave velocity was significantly higher in the complex hypertension group than in the normal blood pressure and exercise-induced hypertension groups (P<0.05); there was no difference in this variable between the normal blood pressure and exercise-induced hypertension groups. The complex hypertension group had a significantly higher augmentation index and augmentation index corrected by 75 beats/min than the exercise-induced hypertension and normal blood pressure groups (P<0.05), while the exercise-induced hypertension group had a higher augmentation index and augmentation index corrected by 75 beats/min than the normal blood pressure group (P<0.05). The maximal oxygen intake was negatively correlated with the peak systolic blood pressure during exercise (r=-0.267, P=0.030), pulse wave velocity (r=-0.246, P=0.048), augmentation index (r=-0.359, P=0.003), and augmentation index corrected by 75 beats/min (r=-0.369, P=0.002). Given the known association of arterial stiffness with cardiovascular disease, runners with exercise-induced hypertension may have an increased risk of cardiovascular events. However, cardiorespiratory fitness correlated negatively with blood pressure and arterial stiffness, which would be beneficial for the vascular health of long-distance runners.

BackgroundDiabetic patients are at the risk of cardiac autonomic neuropathy (CAN) and arterial stiffness. This study aimed to investigate the association of heart rate variability (HRV) as an index for CAN and pulse wave velocity (PWV) as an index for arterial stiffness.MethodsUncomplicated diabetes type-2 patients who had no apparent history of cardiovascular condition underwent HRV and PWV measurements and the results were compared with the control group consisting of non-diabetic peers. Also, the findings were adjusted for the cardiovascular risk factors and other confounding factors.ResultsA total of 64 diabetic patients (age= 52.08±8.50 years; males=33 [51.6%]) were compared with 57 controls (age= 48.74±6.18 years; males=25 [43.9%]) in this study. Hypertension, dyslipidemia, and thereby systolic blood pressure and statin use were significantly more frequent in the diabetic group, while the serum levels of cholesterol, HDL-C and LDL-C were significantly higher in the controls. Pulse wave was significantly increased in the diabetic patients (p<0.001). Main HRV parameters were significantly lower in diabetics than in controls. After adjustment for the confounders, PWV and HRV remained significantly different between the groups (p=0.01 and p=0.004, respectively). Multiple logistic regression of the association between pulse wave velocity and HRV index was independently significant both in diabetics and controls.ConclusionsThere exists a significant relationship between heart rate variability and arterial stiffness as a measure for atherosclerosis in diabetic patients, although the role of the confounding factors is noteworthy.

Heart rate variability (HRV) indices correlate with aging and are related to the autonomic nervous system. However, the trend of HRV with age has not been explored for the Asian population. Therefore, we proposed a linear regression model of HRV indices that decreased with aging in healthy Asian adults. HRV parameters [High frequency (HF), Low frequency (LF), Very low frequency (VLF), Total power (TP), HRV triangular index (HRV-index), Standard deviation of the normal-to-normal interval (SDNN), and Proportion of normal-to-normal intervals greater than 50 ms (pNN50)] were measured in a total of 300 healthy participants (150 men and 150 women) aged 19–69 years stratified into five age groups: 19–29, 30–39, 40–49, 50–59, and 60–69 years comprising 60 people each in Seoul, South Korea. A simple regression analysis was performed to reveal the linear declining trend of HRV indices with age. Independent t-tests were conducted to investigate the gender differences in HRV values depending on each age group. The values of all HRV indices showed a decreasing trend with age in healthy Korean adults, as observed in the Western population (P < 0.001 for all indices); HF (Y = −0.039x + 6.833, R2 = 0.287), LF (Y = −0.047x + 7.197, R2 = 0.414), VLF (Y = −0.025x + 6.861, R2 = 0.177), TP (Y = −0.034x + 8.082, R2 = 0.352), HRV-index (Y = −0.125x + 15.628, R2 = 0.298), SDNN (Y = −0.502x + 53.907, R2 = 0.343), and pNN50 (Y = −0.650x + 53.852, R2 = 0.345) all decreased with age. There was no significant gender difference in any HRV parameter. A linear regression model of various HRV indices has been presented considering the age of healthy Asians, which may be useful to prevent diseases related to the autonomic nervous system by estimating or tracking autonomic functional degeneration in the Asian population.

Background: Brachial ankle pulse wave velocity (BaPWV) and cardio ankle vascular index (CAVI), as indicators of arterial stiffness, are increased in type 2 diabetes. Albuminuria, as a cardiovascular risk factor in type 2 diabetes, can cause endothelial dysfunction and atherosclerosis, and these can increase arterial stiffness. So we investigated the hypothesis that increased albuminuria reflects increased BaPWV and CAVI in type 2 diabetes. Methods: We retrospectively analyzed 106 patients (58 men and 48 women) with type 2 diabetes from March 2005 to September 2006. Urine albumin creatinine ratio (ACR) to evaluate urinary albumin excretion, BaPWV and CAVI were measured in all patients. Results: All patients were divided 3 groups, normal group (ACR 300 mg/g Cr., n = 33). BaPWV and CAVI in microalbuminuria group and proteinuria group are faster than normal group. In bivariate correlation analysis, BaPWV was not associated with ACR, but CA VI was positively correlated to ACR (r = 0.285, P = 0.003). BaPWV was positively correlated to age, diabetes duration, body mass index, systolic blood pressure, diastolic pressure, pulse pressure and negatively correlated to glomerular filtration rate (GFR). CAVI was positively correlated to age, diabetes duration and negatively correlated to GFR. In multiple linear stepwise regression analysis, BaPWV was not associated with ACR, but ACR was independent predictor for CAVI (P = 0.002). Conclusion: In type 2 diabetes, albuminuria was independent predictor for indicators of arterial stiffness,

BackgroundPostoperative delirium (POD) is a common complication after orthopedic surgery in elderly patients. The elderly may experience drastic changes in autonomic nervous system (ANS) activity and circadian rhythm disorders after surgery. Therefore, we intend to explore the relationship between postoperative long-term heart rate (HR) variability (HRV), as a measure of ANS activity and circadian rhythm, and occurrence of POD in elderly patients.MethodsThe study population of this cohort was elderly patients over 60 years of age who scheduled for orthopedic surgery under spinal anesthesia. Patients were screened for inclusion and exclusion criteria before surgery. Then, participants were invited to wear a Holter monitor on the first postoperative day to collect 24-h electrocardiographic (ECG) data. Parameters in the time domain [the standard deviation of the normal-to-normal (NN) intervals (SDNN), mean of the standard deviations of all the NN intervals for each 5-min segment of a 24-h HRV recording (SDNNI), and the root mean square of successive differences of the NN intervals (RMSSD)] and frequency domain [heart rate (HR), high frequency (HF), low frequency (LF), very low frequency (VLF), ultra low frequency (ULF), and total power (TP)] were calculated. Assessment of delirium was performed daily up to the seventh postoperative day using the Chinese version of the 3-Min Diagnostic Interview for CAM-defined Delirium (3D-CAM). The relationship between HRV and POD, as well as the association between HRV and duration of POD, was assessed.ResultsOf the 294 cases that finally completed the follow-up, 60 cases developed POD. Among the HRV parameters, SDNNI, VLF, and ULF were related to the occurrence of POD. After adjustment for potential confounders, the correlation between HRV indices and POD disappeared. Through stratified analysis, two significant negative correlations emerged: ULF in young-old participants and SDNNI, VLF, and ULF in male patients.ConclusionThe lower HRV parameters may be related to the occurrence of POD, and this correlation is more significant in young-old and male patients. ANS disorders and rhythm abnormalities reflected by HRV changes may represent a possible mechanism that promotes POD.

We compare the spectral indices of photoplethysmogram variability (PPGV) estimated using photoplethysmograms recorded from the earlobe and the middle fingers of the right and left hand and analyze their correlation with similar indices of heart rate variability (HRV) in 30 healthy subjects (26 men) aged 27 (25, 29) years (median with inter-quartile ranges) at rest and under the head-up tilt test. The following spectral indices of PPGV and HRV were compared: mean heart rate (HR), total spectral power (TP), high-frequency (HF) and low-frequency (LF) ranges of TP in percents (HF% and LF%), LF/HF ratio, and spectral coherence. We assess also the index S of synchronization between the LF oscillations in HRV and PPGV.The constancy of blood pressure (BP) and moderate increase of HR under the tilt test indicate the presence of fast processes of cardiovascular adaptation with the increase of the sympathetic activity in studied healthy subjects. The impact of respiration on the PPGV spectrum (accessed by HF%) is less than on the HRV spectrum. It is shown that the proportion of sympathetic vascular activity (accessed by LF%) is constant in the PPGV of three analyzed PPGs during the tilt test. The PPGV for the ear PPG was less vulnerable to breathing influence accessed by HF% (independently from body position) than for PPGs from fingers. We reveal the increase of index S under the tilt test indicating the activation of interaction between the heart and distal vessels. The PPGV spectra for finger PPGs from different hands are highly coherent, but differ substantially from the PPGV spectrum for the ear PPG. We conclude that joint analysis of frequency components of PPGV (for the earlobe and finger PPGs of both hands) and HRV and assessment of their synchronization provide additional information about cardiovascular autonomic control.

The unnormalized spectral indices of heart rate variability should be presented in conjunction with normalized versions of the same variables

Silent myocardial ischemic episodes as well as decreased heart rate variability (HRV) indices are associated with an unfavorable outcome in patients with coronary artery disease. Nipradilol, which is a nonselective beta-adrenergic and nitrate-like vasodilator anti-anginal agent developed in Japan, may ameliorate silent myocardial ischemia, while it also improves exercise tolerance and HRV indices in patients with chronic stable angina. To investigate the effect of nipradilol (6 mg daily) on silent myocardial ischemic episodes and HRV indices, and to study its effect on the relationship between them, 24 patients with chronic stable angina underwent exercise treadmill testing and a 24-hour ambulatory electrocardiogram (ECG). The study protocol utilized a single blind, 4-week placebo-controlled design. The HRV indices from ambulatory ECG included mean RR (ms), SDNN (ms), SDANN (ms), SD (ms), rMSSD (ms), pNN50 (%); frequency analysis of HRV consisted of total (ms, 0.01-1.00 Hz), low (ms, 0.04-0.15 Hz) and high (ms, 0.15-0.40 Hz) components. Nipradilol significantly decreased the mean heart rate at submaximal and maximal exercise and the mean pressure rate product at submaximal and maximal exercise. It significantly improved exercise-induced maximal ST segment depression from -1.7 +/- 0.6 mm to -1.1 +/- 0.7 mm (p < 0.05). Silent myocardial ischemic episodes recorded during the 24-hour ambulatory ECG significantly decreased after nipradilol administration. Nipradilol also significantly influenced several HRV indices as well as the relationship between silent myocardial ischemic episodes and the HRV indices. Nipradilol significantly increased SD, rMSSD, pNN50, total spectra, low frequency spectra and high frequency spectra. In addition, nipradilol significantly decreased the LF/HF ratio from 1.7 (1.5-2.0) to 1.5 (1.3-1.8). These effects of nipradilol on HRV indices concomitantly occurred with the reduction in silent myocardial ischemic episodes. Nipradilol was found to effectively improve the episodes of silent myocardial ischemia as well as exercise-induced ischemia probably due to its beta-blocking properties and not nitrate-like actions. In addition, nipradilol also had a favorable effect on the HRV indices.

BackgroundKratom is a psychoactive plant used to enhance productivity among laborers in Southeast Asian countries. Previous findings from in vitro research of mitragynine, a major component of kratom, suggested a possible risk of heart function abnormality. However, the cardiac autonomic function in long-term kratom users with chewing forms has never been studied. This study aimed to investigate heart rate variability (HRV) indices of cardiac autonomic function in long-term kratom chewers (LKC), compared to the control levels, and also to examine the correlation between HRV indices and relevant kratom use factors.MethodA total number of 50 participants consisted of LKC (n = 31) who regularly chewed fresh kratom leaves for at least 2 years and demographically matched control subjects (n = 19). Resting electrocardiogram (ECG) signals were recorded from subjects for 3 min to analyze the ultrashort HRV in the frequency domain. The normalized low frequency (LFn) and high frequency (HFn) were chosen to be the HRV indices to evaluate cardiac autonomic function. The comparison of HRV indices between groups and the correlation between HRV indices and duration and quantity of kratom use was further conducted in statistical analysis.ResultsThe LKC significantly increased LFn together with enhanced HFn compared to the control group tested, indicating that LKC changed cardiac autonomic function with parasympathetic dominance. Furthermore, no significant correlation between the HRV indices and the duration and quantity of kratom use was found, suggesting that the HRV indices were not relevant to these factors. The present study provided scientific-based evidence of cardiac autonomic modulation in long-term kratom chewers. LFn and HFn may be promising cardiac autonomic indicators for monitoring health outcomes in LKC.

This study was designed to examine the associations of an exaggerated systolic blood pressure (SBP) response to exercise with the indices of nitric oxide (NO) bioavailability, oxidative stress, inflammation and arterial stiffness in normotensive females. The subjects included 84 normotensive females without a history of cardiovascular disease or stroke who were not taking any medications. Each subject performed a multistage graded submaximal exercise stress test using an electric bicycle ergometer, and their blood pressure was measured at rest and during the last minute of each stage. The brachial-ankle pulse wave velocity, plasma nitrate/nitrite (NOx), plasma thiobarbituric acid-reactive substances, high-sensitivity C-reactive protein (hs-CRP) and fibrinogen levels and the white blood cell count were measured. An exaggerated SBP response to exercise was defined according to the criteria of the Framingham Study (peak SBP: ⩾190 mm Hg). An exaggerated SBP response to exercise was observed in 27 subjects. A multiple logistic regression analysis revealed that the hs-CRP (odds ratio (OR): 1.05, 95% confidence interval (CI): 1.03-1.07, P=0.015) and plasma NOx levels (OR: 0.92, 95% CI: 0.87-0.98, P=0.014) were significantly associated with an exaggerated SBP response to exercise. Furthermore, the percent change in SBP was found to be significantly associated with an increase in the hs-CRP (P for trend=0.006) and a decrease in the plasma NOx levels (P for trend=0.001). These results suggest that an exaggerated SBP response to exercise was associated with the NO bioavailability and inflammatory status in normotensive females.

Funding Acknowledgements Type of funding sources: None. Background An exaggerated blood pressure (BP) response to exercise may be an early indicator of hypertension. However, it is common in endurance athletes and the association between systolic blood pressure (SBP) during exercise and hypertension is not well established in this group. Purpose To establish whether there is an association between exercise-induced hypertension (EIH) and clinical hypertension in endurance athletes. Methods 250 current and former endurance athletes (16-80 years, 75% male) performed a maximal exercise test on a cycle ergometer with BP measured every 2 min. Athletes were diagnosed with EIH based on international guidelines (SBP ≥210mmHg males, ≥190mmHg females). The relationship between SBP and workload was determined by linear regression analysis. Office hypertension was identified from either supine SBP ≥140mmHg or diastolic BP ≥90mmHg, or if treated for hypertension. Gold-standard 24-hour ambulatory blood pressure monitoring (ABPM) was performed in a subset of 42 athletes with EIH and 9 athletes with a normotensive response to exercise (NRE). Results On average, peak exercise SBP values were universally high (221±26mmHg in males and 199±21mmHg in females). 71% of athletes (70% of males and 74% of females) met criteria for EIH of which 12% had a peak SBP≥250mmHg. EIH and NRE groups were of similar age, sex, body mass index (BMI) and fitness (Figure 1). The strongest determinant of peak exercise SBP was exercise workload (R=0.78, P&amp;lt;0.001), which remained significant after adjusting for age, sex, BMI and antihypertensive medication (p&amp;lt;0.001) In the full cohort, resting SBP was higher in the EIH group (EIH: 128±13mmHg vs NRE: 122±15mmHg, P=0.006 – Figure 1), however there was a similar prevalence of office hypertension between the EIH (19%) and NRE (15%) groups (P=0.59). This prevalence remained similar (EIH: 13% vs NRE: 10%, P=0.49) after excluding those being treated for hypertension (n=15). In the subset of athletes who underwent 24h ABPM (n=51), there were no diagnoses of clinical hypertension in NRE (n=9, Figure 1). Of the 42 athletes with EIH, a majority (n=32, 76%) were normotensive on ABPM. In the 10 athletes with EIH and hypertension on ABPM, the majority were classified with Grade 1 hypertension (n=5) or daytime hypertension (n=3). Interestingly only two of these athletes would have been identified with office BP measures (see Figure 2). Conclusion EIH is common in endurance athletes and is strongly associated with peak exercise workloads suggesting this may be a reflection of superior cardiovascular fitness. In a small proportion of athletes, EIH may be associated with mild hypertension.

[PURPOSE] This study attempted to show the relationship between exercise-induced hypertension response and arterial stiffness in men aged 50 years. [METHODS] The subjects of the study were adults male with exercise induced hypertension group (n=45, age 56.22±2.60 years) and control group (n=61, age 56.01±1.57 years) who had undergone exercise test and arterial stiffness test. Exercise induces hypertension is defined as a peak systolic blood pressure ≥210mmHg during treadmill tests. Exercise stress test was conducted using modified Balke protocol. Arterial stiffness was assessed based on brachial-ankle pulse wave velocity (baPWV). [RESULTS] Exercise induced hypertension group showed significantly higher baPWV than that of control group (1416.5±154.09cm/sec vs. 1309.5±127.76cm/sec, p<.001). The peak systolic blood pressure was correlated with the resting heart rate (r=0.198, p<.05), resting systolic blood pressure (r=0.190, p<.05), and baPWV (r=0.461, p<.001). In multiple linear regression analysis, we found that the baPWV was a significant predictor of peak systolic blood pressure (β=0.429, p<.001). [CONCLUSIONS] Exaggerated blood pressure response to exercise was associated with arterial stiffness.