Baroreflex Sensitivity Parameters Research Articles

Differences in Heart Rate Variability and Baroreflex Sensitivity between Male and Female Athletes.

Heart rate variability (HRV), systolic blood pressure variability (BPV), and spontaneous baroreflex sensitivity (BRS) are indirect and approximate measures of autonomic regulation of the cardiovascular system. Studies have shown differences in HRV and BRS between males and females; however, no study has observed differences in BPV, HRV, or BRS between male and female athletes. One hundred males (age 21.2 ± 2.1 y; BMI 27.4 ± 4.5 kg/m2) and sixty-five females (age: 19.7 ± 1.6 y; BMI 22.7 ± 2.2 kg/m2) were assessed during the pre-season baseline. We collected resting beat-to-beat blood pressure and R-R intervals using finger photoplethysmography and a 3-lead electrocardiogram, respectively. Participants underwent a controlled slow breathing protocol (six breaths/minute: 5 s inhale, 5 s exhale) for 5 min. Spectral and linear analysis was conducted on blood pressure and ECG data. Regression curves were fitted to the blood pressure and R-R signals, with the slopes providing the BRS parameters. Male athletes had significantly (p < 0.05) lower mean heart rate, RR interval SD2/SD1, HRV % low-frequency, and higher BP high-frequency power during controlled respiration. No differences were found in any BRS parameters. HRV and BPV responses to a slow breathing protocol differed between male and female athletes; however, BRS responses did not.

Effects of age and sex on vasomotor activity and baroreflex sensitivity during the sleep–wake cycle

Cardiovascular function is related to age, sex, and state of consciousness. We hypothesized that cardiovagal baroreflex sensitivity (BRS) demonstrates different patterns in both sexes before and after 50 years of age and that these patterns are associated with patterned changes during the sleep–wake cycle. We recruited 67 healthy participants (aged 20–79 years; 41 women) and divided them into four age groups: 20–29, 30–49, 50–69, and 70–79 years. All the participants underwent polysomnography and blood pressure measurements. For each participant, we used the average of the arterial pressure variability, heart rate variability (HRV), and BRS parameters during the sleep–wake stages. BRS and HRV parameters were significantly negatively correlated with age. The BRS indexes were significantly lower in the participants aged ≥ 50 years than in those aged < 50 years, and these age-related declines were more apparent during non-rapid eye movement sleep than during wakefulness. Only BRS demonstrated a significantly negative correlation with age in participants ≥ 50 years old. Women exhibited a stronger association than men between BRS and age and an earlier decline in BRS. Changes in BRS varied with age, sex, and consciousness state, each demonstrating a specific pattern. The age of 50 years appeared to be a crucial turning point for sexual dimorphism in BRS. Baroreflex modulation of the cardiovascular system during sleep sensitively delineated the age- and sex-dependent BRS patterns, highlighting the clinical importance of our results. Our findings may aid in screening for neurocardiac abnormalities in apparently healthy individuals.

Effect of acute hyperglycemia on baroreflex sensitivity in healthy young adults.

Autonomic dysfunction, impaired baroreflex sensitivity (BRS), and deranged circulatory homeostasis have been observed in chronic hyperglycemia and found to be associated with increased cardiovascular morbidity and mortality. However, the acute effects of hyperglycemia in healthy subjects have been rarely studied. The present study explores the effect of acute hyperglycemia on conventional and unconventional parameters of BRS in healthy young adults. For the estimation of BRS beat-to-beat blood pressure (BP) and electrocardiogram were recorded in forty-two young, healthy subjects during fasting and at 1hr of the oral glucose load. Analysis of BRS was carried out by sequence and spectral method. Number of UP-, DOWN- and ALL-sequences between ramps of BP and RR-interval were calculated as an unconventional measure of BRS along with the other conventional parameters. We observed significant alteration of unconventional parameters of autonomic functions [the number of sequences of UP- (p = 0.0039) and ALL-sequences (p = 0.0233) of systolic BP and RR interval; and, UP- (p = 0.0380), DOWN- (p = 0.0417) and ALL-sequences (p = 0.0313) of mean BP and RR- interval] during acute hyperglycemia as compared to the fasting state. However, no significant changes were observed in any of the conventional parameters of BRS during acute hyperglycemia as compared to the fasting state. Present study concludes that the unconventional parameters of BRS - the number of sequences between the ramp of BP and RR-interval - change significantly during acute hyperglycemia. However, the conventional parameters do not show significant changes during acute hyperglycemia. We may hypothesize that the relatively constant BRS is maintained at the expense of increased oscillations in the ramp of BP and RR-interval.

Pancreatic exocrine insufficiency in diabetes is associated with autonomic dysfunction

Objectives Pancreatic exocrine insufficiency (PEI) is prevalent in diabetes. Pathophysiological theories imply autoimmune destruction, lack of trophic effects of insulin or impaired neuronal stimulation, but the relationship between PEI and autonomic dysfunction is largely unknown. In a pilot study, we aimed to investigate if patients with diabetes and PEI had impaired autonomic function. Methods We measured faecal elastase in 59 patients with type 1 or 2 diabetes, using a cut-off-value <200 μg/g to define PEI. Based on faecal elastase results, patients were stratified into matched case (n = 8) and control groups (n = 13). We used heart rate variability, baroreflex sensitivity and orthostatic hypotension tests to assess autonomic dysfunction. Results All baroreflex sensitivity parameters were reduced in cases with PEI compared with controls (all p < .05). The heart rate variability parameters root mean square of successive RR interval differences (p = .05) and high frequency (p = .04) were also reduced. We found no difference in orthostatic hypotension between the groups. Conclusions In this first-of-its-kind study, we found that diabetes patients with PEI had reduced autonomic function compared with matched controls. Although numbers are small, results support the hypothesis that autonomic dysfunction could be a contributor to PEI in diabetes.

Assessment of the association of heart rate variability and baroreflex sensitivity with depressive symptoms and stress experienced by women in pregnancy

BackgroundPregnancy is a unique physiological state with systemic changes including cardiovascular, autonomic, hemodynamic and psychological. Increase in incidence of stress and depression in antenatal period has been reported. Autonomic changes in pregnancy and its dysfunction in depression are well documented. However, there is lack of evidence associating cardiovascular autonomic dysfunction to stress and depressed mood in pregnant women. MethodsIn this correlation study, we assessed cardiovascular autonomic functions of 172 pregnant women using heart rate variability (HRV) and baroreflex sensitivity (BRS). The Edinburg postnatal depression scale (EPDS) was used to evaluate depressive symptoms and perceived stress scale (PSS) was used to assess stress. The HRV and BRS parameters were correlated with EPDS and PSS. Multiple regression analysis was performed for EPDS and PSS individually to study their association with cardiac autonomic functions(CAF). ResultsHRV and BRS were well correlated to EPDS and PSS scores. The depression and stress were found to be significantly associated to autonomic dysfunctions as increased sympathetic and decreased parasympathetic activity. Among various CAF parameters, LF:HF ratio and BRS were found to be significantly associated with depression and stress among these women. ConclusionLF:HF ratio and BRS may be associated with depression during antenatal period. The depression in antenatal period may add on to cardiovascular risk in expecting mothers.

Impaired Baroreflex Sensitivity in Patients with Recent-Onset Type 2 Diabetes

Impaired baroreflex sensitivity (BRS) is a sign of diabetic cardiovascular autonomic neuropathy (CAN) which often remains undiscovered during the early course of diabetes. We aimed to determine whether BRS alterations can be detected in patients with recent-onset type 1 and type 2 diabetes. Continuous plethysmographic arterial pressure and R-R intervals were recorded using the Finometer (Finapres Medical Systems) from the left middle finger in 586 participants from the baseline German Diabetes Study (GDS) cohort with type 1 or type 2 diabetes and a known diabetes duration ≤1 year (T1D/T2D [mean±SD]: n=208/378; age: 34.7±11.1/51.6±10.3 years; male: 60/74%; BMI: 24.7±4.2/31.7±6.3 kg/m²; diabetes duration: 6.3±3.3/5.9±3.5 months; HbA1c: 6.5±1.1/6.5±0.9%) and corresponding controls (CON1/CON2: n=74/208; age: 36.4±10.1/49.4±14.8 years; male: 64/64%; BMI: 26.5±4.9/26.6±4.9 kg/m²; HbA1c: 5.2±0.3/5.3±0.3%). BRS parameters included the alpha index of spectral power (BRSα), transfer function cross spectrum (xBRS), and sequence analyses (BRSseq). After adjustment for sex, age, BMI, and smoking, all three BRS measures were reduced in T2D vs. CON2 (BRSα: 10.1±8.6 vs. 15.4±10.2 ms/mmHg; xBRS: 7.84±6.94 vs. 10.4±8.2 ms/mmHg; BRSseq: 9.85±9.07 vs. 13.3±9.6 ms/mmHg) (P≤0.01), while no such differences were observed in T1D vs. CON1. Multiple regression analyses revealed, that systolic blood pressure (SBP) was the strongest determinant of lower BRS in T2D (xBRS/BRSseq/BRSα: β=-0.32/-0.23/-0.22) followed by age (xBRS: β=-0.18) and lower HDL cholesterol (BRSseq: β=-0.23), while in T1D it was age (xBRS/BRSseq/BRSα: β=-0.37/-0.36/-0.34), SBP (xBRS/BRSα: β=-0.26), and BMI (BRSseq: β=-0.24) (all P≤0.01). In conclusion, reduced baroreflex sensitivity indicates early CAN in recent-onset type 2 diabetes in relation to modifiable risk factors such as higher systolic blood pressure and lower HDL cholesterol. Disclosure G.J. Bönhof: None. A. Strom: None. K. Bódis: None. K. Müssig: None. J. Szendroedi: None. M. Roden: Speaker's Bureau; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH. Consultant; Self; Poxel SA. Research Support; Self; Danone Nutricia Early Life Nutrition, GlaxoSmithKline plc., Nutricia Advanced Medical Nutrition, Sanofi. D. Ziegler: None.

Pathophysiological mechanisms of noncardiac syncope in athletes

ObjectiveThe investigation of the differences in orthostatic responses of individuals with a history of noncardiac syncope(NCS) between athletes and nonathletes. MethodsA passive tilt test for 30min was performed in 133 athletes (54 with NCS, 79 without NCS) and 48 nonathletes (15 with NCS, 33 without NCS). We performed measurement of haemodynamic, heart rate variability and baroreflex sensitivity parameters. All comparisons were adjusted for age, gender and body mass index(BMI). ResultsAthletes with NCS had increased heart rate(HR) (90±11 vs 81±10bpm, p=0.001) and decreased total peripheral resistance index(TPRI) (2227±408 vs 2918±733dynesm2/cm5, p=0.039) and baroreflex effectiveness index(BEI) [70.16(37.42–89.71) vs 72.19(48.49–91.35)%, p=0.016] compared with athletes without NCS. After applying backward stepwise logistic regression analysis to predict history of NCS in athletes, the final model included age, gender, BMI, HR and TPRI. Nonathletes with NCS had increased HR (95±24 vs 83±11bpm, p=0.024) and TPRI (3744±1606 vs 2937±880dynesm2/cm5, p=0.030) and decreased stroke index(SI) (25.4±7.6 vs 33.0±7.5mL/m2, p=0.003) compared with nonathletes without NCS. After applying backward stepwise logistic regression analysis to predict history of NCS in nonathletes, the final model included SI and HR. Among individuals with NCS, athletes had increased SI and BEI and decreased HR and TPRI compared with nonathletes. Among individuals without NCS, a positive result of tilt test was less frequent in athletes compared with nonathletes (p=0.031). ConclusionsThe possible main underlying mechanism for NCS during upright standing in athletes is the decreased TPRI, while the inadequate preservation of SI in nonathletes.

A novel strategy for evaluating tilt test in athletes with syncope.

The tilt test is used for the diagnosis of reflex syncope (RS) and is characterized by low sensitivity, especially in athletes. The objective of the study was the implementation of a novel diagnostic strategy for the tilt test without pharmacologic provocation in athletes based on haemodynamic criteria. A passive tilt test for 30 min was performed in 132 athletes (53 with a history of RS, 79 without RS). Measurement of haemodynamic, heart rate variability (HRV) and baroreflex sensitivity parameters was performed. Tilt testing yielded 34% sensitivity and 94% specificity. Among negative tilt test responders, the ones with RS had increased heart rate (HR) (89 ± 11 vs 81 ± 10 bpm, p < 0.001), stroke index (SI) (40.2 ± 7.1 vs 35.5 ± 9.7 ml/m(2), p = 0.013), cardiac index (CI) (3.5 ± 0.6 vs 2.8 ± 0.8 l/(min·m(2)), p < 0.001) and decreased total peripheral resistance index (TPRI) (2230 ± 362 vs 2965 ± 725 dyne·s m(2)/cm(5), p < 0.001), low frequency component of HRV (76.2% (49.0-88.4) vs 79.7% (10.2-91.1), p = 0.045) during head-up tilt, compared with those without RS. Receiver-operating characteristic (ROC) curve analysis showed that among athletes with a negative tilt test the area under the curve (AUC) values were 0.727 (0.626-0.828) for HR (p < 0.001), 0.707 (0.611-0.804) for SI (p = 0.001), 0.847 (0.774-0.920) for CI (p < 0.001), 0.830 (0.754-0.905) for TPRI (p < 0.001). Further stratification of negative tilt test responders, characterizing their results as positive when TPRI <2800 dyne·s m(2)/cm(5) and CI >3 l/(min·m(2)), resulted in 85% sensitivity and 76% specificity. Our results provide supportive evidence that a novel stratification based on haemodynamic criteria can improve the sensitivity of the tilt test for the diagnosis of RS in athletes.

Impact of cardiac surgery on the autonomic cardiovascular function

The study compares the impact of cardiac surgical interventions on the autonomic function by assessing the pre-operative status and early post-operative recovery of subjects undergoing isolated mitral valve replacement (MVR), isolated aortic valve replacement (AVR), and transcatheter aortic valve implantation (TAVI). We analyze heart rate variability (HRV), baroreflex sensitivity (BRS), and cardiovascular coupling in a longitudinal, i.e., the temporal evolution of autonomic function within each group before, 1 day after, and 7 days after surgery, and a transversal, i.e., between groups of patients at identical time instants, setting. A total of 243 records from 124 patients (38 MVR, 57 AVR, 29 TAVI) was analyzed. There were no major differences in HRV, BRS, and coupling between the groups in the pre-operative values. Longitudinal analysis proves a depressed autonomic function for MVR and AVR patients after surgery (in MVR patients, p<0.001 for most parameters related to HRV and BRS), but not for TAVI patients. TAVI patients showed no differences before and after surgery. Transversal analysis reveals the strongest impairments throughout HRV and BRS parameters for MVR patients. In the case of AVR, the autonomic regulation was also depressed, though not to the extent as seen in MVR patients. Cardiovascular coupling by means of symbolic coupling traces (SCT) was shown to be clearly reduced the day after surgery in MVR and AVR patients. In TAVI patients, there was no reduction but already the day after surgery developed additional couplings. Our results prove a characteristic behavior of the autonomic function in relation to the gravity of the surgical procedure. As variables related to the process of the surgical interventions were kept similar between patient groups, direct surgical trauma is assumed to be responsible for the heavy decrease of autonomic function in the case of MVR. TAVI, in contrast, proves to be very suited in terms of maintaining the autonomic function in comparison to AVR. Further studies incorporating larger populations should confirm our findings and relate the autonomic state to malignant events after surgical interventions to build the fundament of a strengthened inclusion of cardiovascular variability and coupling analysis in the pre-, peri-, and post-operative care.

Acute Changes in Ambient Temperature Are Associated With Adverse Changes in Cardiac Rhythm.

Both increases and decreases in ambient temperature have been associated with increased cardiovascular mortality and morbidity. However, the mechanism(s) remain unclear. We examined associations between biomarkers of pathways thought to, in part, explain these associations and changes in ambient temperature in a panel of predominantly post-myocardial infarction or post-stent patients. We studied 76 subjects who had a recent coronary event and were participating in a cardiac rehabilitation program. In these patients, we measured heart rate variability, repolarization, and baroreflex sensitivity parameters using Holter ECG recordings before and during supervised, graded, twice weekly, exercise sessions. Hourly temperature measurements were made at a monitoring site near the rehabilitation center. Using linear mixed models, we observed decreases in rMSSD (square root of the mean of the sum of the squared differences between adjacent NN intervals) and deceleration capacity, associated with increases in ambient temperature in the previous four days. Additionally, decreased rMSSD was associated with both increasing temperature (mean in previous 6 hours) in the summer and decreasing temperature (mean in the previous 3 weeks) in the winter. In a panel of cardiac rehabilitation patients, changes in ambient temperature were associated with decreases in markers of heart rate variability and baroreflex sensitivity, which may lead to increased risk of arrhythmic events and sudden death in post-infarction patients.

Cardiovascular variability before and after delivery: recovery from arterial stiffness in women with preeclampsia 4 days post partum

Objective: We studied the short-term response of autonomic control to delivery in normal pregnancies and pregnancies with preeclampsia (PE). Methods: Fourteen healthy pregnant women and 13 women with PE were monitored within four days before and four days after delivery and compared to values of 14 non-pregnant women as controls using high-resolution electrocardiogram and noninvasive continuous blood pressure monitoring. Results: In PE, blood pressure remained elevated four days postpartum, but markers for arterial stiffness normalized. In contrast, none of heart rate variability and baroreflex sensitivity parameters, altered due to either pregnancy or disease, were normalized 96 h after delivery. Conclusion: Four days after delivery, the maternal cardiovascular system is still strongly affected by pregnancy independent of the health status.

Impaired baroreflex sensitivity and the risks of new-onset ambulatory hypertension, in an elderly population-based study

Impairment of the autonomic nervous system activity may be involved in the development of hypertension. Yet the prognostic values of heart rate variability and baroreflex sensitivity in the risk of new-onset ambulatory hypertension have not been investigated. We sought to assess the relationship between heart rate variability and baroreflex sensitivity parameters and ambulatory hypertension in a community-dwelling elderly cohort. Normotensive subjects were selected from the PROOF study cohort, including 1011 subjects aged 65 years at baseline. The autonomic nervous system activity was assessed through 24-hour heart rate variability and 15-minute spontaneous baroreflex sensitivity at baseline. Incident hypertension was defined with the 24-hour, day-time and night-time ambulatory blood pressure measurements and antihypertensive treatment use, at two-years of follow-up. At baseline, 13.7% of subjects developed day-time hypertension, 18.2% developed night-time hypertension and 13.6% developed 24-hour hypertension. Reduced baroreflex sensitivity at baseline was associated with onset of hypertension after adjustment for blood pressure level, C-reactive protein levels and depression score (OR = 0.45 [0.23-0.86]). Indices of heart rate variability were not associated with hypertension onset. Baroreflex sensitivity may represent an intermediate goal for prevention of ambulatory hypertension at early stage.

Left ventricular diastolic dysfunction is associated with impaired baroreflex at rest and during orthostatic stress in hypertensive patients with left ventricular hypertrophy

The study aimed to determine the relationship between left ventricular (LV) diastolic function and the heart's spontaneous baroreflex at rest and in response to orthostatic stress during a prospective follow-up of hypertensive patients with LV hypertrophy (LVH+). LV structure and function and baroreflex sensitivity (BRS) during tilt testing were evaluated in 24 LVH+ patients and compared with 25 age-matched healthy controls and 25 hypertensive patients without LVH (LVH-). Clinical status, diastolic function and BRS were then assessed in LVH+ patients during treatment with telmisartan (monotherapy or combined with hydrochlorothiazide and/or amlodipine) at 6- and 18-month follow-ups. LVH+ patients had significantly altered diastolic function indices and decreased BRS as compared with healthy controls and LVH- patients. During the 18-month follow-up, favorable changes in diastolic function were associated with improvement in BRS at rest and during tilting. In multivariate regression models, an index reflecting rate of LV myocardial relaxation (E'sept) where E'sept denotes peak early diastolic velocity at the septal mitral annulus and a surrogate for LV filling pressure (E/E'sept), independently from other clinical and echocardiographic variables related to the low-frequency component of BRS during tilting. In conclusion, the LV diastolic function indices have independent associations with BRS parameters obtained at rest and during orthostatic stress in LVH+ patients receiving long-term pharmacological intervention.

Unstable sleep and higher sympathetic activity during late‐sleep periods of rats: implication for late‐sleep‐related higher cardiovascular events

We proposed that the higher incidence of sleep fragmentation, sympathovagal imbalance and baroreceptor reflex impairment during quiet sleep may play a critical role in late-sleep-related cardiovascular events. Polysomnographic recording was performed through wireless transmission using freely moving Wistar-Kyoto rats over 24 h. The low-frequency power of arterial pressure variability was quantified to provide an index of vascular sympathetic activity. Spontaneous baroreflex sensitivity was assessed by slope of arterial pressure-RR linear regression. As compared with early-light period (Zeitgeber time 0-6 h), rats during the late-light period (Zeitgeber time 6-12 h) showed lower accumulated quiet sleep time and higher paradoxical sleep time; furthermore, during quiet sleep, the rats showed a lower δ% of electroencephalogram, more incidents of interruptions, higher σ% and higher β% of electroencephalogram, raised low-frequency power of arterial pressure variability value and lower baroreflex sensitivity parameters. During the light period, low-frequency power of arterial pressure variability during quiet sleep had a negative correlation with accumulated quiet sleep time and δ% of electroencephalogram, while it also had a positive correlation with σ% and β% of electroencephalogram and interruption events. However, late-sleep-related raised sympathetic activity and sleep fragmentation diminished when an α1-adrenoceptor antagonist was given to the rats. Our results suggest that the higher incidence of sleep fragmentation and sympathovagal imbalance during quiet sleep may play a critical role in late-sleep-related cardiovascular events. Such sleep fragmentation is coincident with an impairment of baroreflex sensitivity, and is mediated via α1-adernoceptors.

Autonomic nervous function and baroreflex sensitivity in hypertensive diabetic patients

Objective Little is known about how the cardiac autonomic nervous function (CAN) changes with gradually increasing systolic blood pressure (SBP). This study investigated cardiac autonomic nervous function in diabetic patients and controls with different grades of SBP.Methods and results We measured heart rate variability (HRV) and spontaneous baroreflex sensitivity (BRS) by power spectral analysis in 118 Chinese type-2 diabetic patients and 137 age-matched controls. Subjects were further subdivided into 4 SBP groups. Results showed total HRV and BRS values were significantly lower in several diabetic SBP groups. Total HRV and BRS decreased with increasing SBP, with significant differences in the 140-159 mm Hg or 160-179 mm Hg groups compared with other groups of diabetic and control subjects.Conclusions We found that HRV and BRS can reflect cardiovascular autonomic dysfunction of diabetes when accompanied by hypertension. In our selected Chinese diabetic and control subjects, HRV and BRS parameters were influenced by gradually increasing SBP.

Autonomic modulation in healthy first-degree relatives of patients with major depressive disorder

Cardiac mortality is known to be increased in patients with major depression. Several studies have reported an imbalance within the autonomic nervous system (ANS) of patients with major depressive disorder (MDD) as one putative cause. Since a heritability of autonomic modulation was demonstrated in healthy subjects, we aimed to investigate autonomic modulation in first-degree relatives of patients with MDD to find potential autonomic imbalances. We included 30 patients with MDD, 30 of their first-degree relatives (siblings or offspring) and 30 matched healthy controls in our study. We obtained a high resolution electrocardiogram and beat to beat blood pressure measurements for 30 min at rest. Linear and nonlinear parameters of heart rate variability (HRV) and baroreflex sensitivity (BRS) were calculated. Parameters of HRV and BRS did not differ significantly between relatives and controls. We found significant differences between patients and controls for some HRV and BRS parameters confirming results of previous studies. Findings of our study suggest that an imbalance of autonomic function is related to patients with depression and not to first-degree relatives. Thus, a genetic background for autonomic dysfunction is rather unlikely.

Preserved autonomic regulation in patients undergoing transcatheter aortic valve implantation (TAVI) – a prospective, comparative study

Heart rate and blood pressure variability as well as baroreflex sensitivity (BRS) lead to additional insights on the patients' prognosis after cardiovascular events. The following study was performed to assess the differences in the postoperative recovery of the autonomic regulation after transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR). Fifty-eight consecutive patients were enrolled in a prospective study; 24 underwent TAVI and 34 SAVR. BRS was calculated according to the Dual Sequence Method, heart rate variability (HRV) was evaluated using standard linear as well as nonlinear parameters. HRV and BRS parameters were reduced after surgery in patients with SAVR only (meanNN: p<0.001, sdNN: p<0.05, Shannon: p<0.01, BRS: p<0.01), while these indexes were preserved in patients after TAVI. Simultaneously, an increased complexity of blood pressure (BP) in SAVR patients (fwShannon: p<0.001, fwRenyi4: p<0.001), but not in TAVI patients was recorded. In this study we were able to demonstrate for the first time that, in contrast to patients undergoing conventional open surgery, there are fewer alterations of the cardiovascular autonomic system in patients with TAVI.

The interaction between pupil function and cardiovascular regulation in patients with acute schizophrenia

Objective Cardiac autonomic dysregulation has been reported in patients with schizophrenia. However, there are no definite data examining whether other branches of the autonomic nervous system are compromised as well and how they interrelate with cardiac function. In this study, we tested the hypothesis that the autonomic dysregulation at the heart is reflected in the regulation of the pupillary light reflex. Methods We assessed heart rate variability and baroreflex sensitivity parameters as well as pupillographic measures in 28 unmedicated patients with schizophrenia and compared these measures to those of 28 controls. In addition, cardiovascular and pupillographic parameters were correlated in both groups. Results The obtained cardiovascular parameters indicated decreased parasympathetic modulation. Patients showed a significantly increased resting pupil diameter as well as reduced relative amplitude, suggesting a dominance of sympathetic control and a lack of parasympathetic modulation at the pupil. Intriguingly, the parasympathetic latency of the pupil constriction was similar in both groups and correlated with several cardiovascular parameters. These correlations were in the opposite direction in patients compared to controls. Furthermore, shorter latencies of the pupil constriction were associated with symptom severity in patients. Conclusions Overall, we found evidence for an autonomic dysregulation at the pupil and heart in patients with schizophrenia. Future studies are warranted to describe this complex interaction at different levels of the autonomic system. Significance The interrelationship of both the systems indicates that the autonomic dysfunction affects the regulation in different branches of the autonomic network as well as their interaction in schizophrenia.

Office and out of office heart rate measurements: which clinical value?

Office and out of office heart rate measurements: which clinical value?

Decreased baroreflex sensitivity in acute schizophrenia

Decreased vagal activity has been described in acute schizophrenia and might be associated with altered cardiovascular regulation and increased cardiac mortality. The aim of this study was to assess baroreflex sensitivity in the context of psychopathology. Twenty-one acute, psychotic, unmedicated patients with a diagnosis of paranoid schizophrenia were investigated after admission to the hospital. Results were compared with 21 healthy volunteers matched with respect to age and sex. Cardiovascular parameters obtained included measures for heart rate variability, baroreflex sensitivity, as well as cardiac output, left ventricular work index, and total peripheral resistance. All parameters investigated were analyzed using linear and novel nonlinear techniques. Positive and negative symptoms were assessed to estimate the impact of psychopathology on autonomic parameters. Subjects with acute schizophrenia showed reduction of baroreflex sensitivity accompanied by tachycardia and greatly increased left ventricular work index. Nonlinear parameters of baroreflex sensitivity correlated with positive symptoms. For heart rate variability, mainly parameters indicating parasympathetic modulation were decreased. Vascular pathology could be excluded as a confounding factor. These results reflect a dysfunctional cardiovascular regulation in acute schizophrenic patients at rest. The changes are similar to adaptational regulatory processes following stressful mental or physical tasks in healthy subjects. This study suggests that hyperarousal in acute schizophrenia is accompanied by decreased efferent vagal activity, thus increasing the risk for cardiovascular mortality. Future studies are warranted to examine the role of the sympathetic system and possible autonomic differences in hyperarousal induced by anxiety and/or external stressful events.