RT variability unrelated to heart period and respiration progressively increases during graded head-up tilt

2010 ◽  
Vol 298 (5) ◽  
pp. H1406-H1414 ◽  
Author(s):  
Alberto Porta ◽  
Eleonora Tobaldini ◽  
Tomaso Gnecchi-Ruscone ◽  
Nicola Montano
Keyword(s):  
Random Order ◽  
Open Loop ◽  
Parametric Models ◽  
Heart Period ◽  
Tilt Table ◽  
Indirect Measure ◽  
T Wave ◽  
Healthy Humans ◽  
Surface Ecg ◽  
Head Up Tilt

Open-loop linear parametric models were exploited to describe ventricular repolarization duration (VRD) variability during graded head-up tilt. Surface ECG and thoracic movements were recorded in 15 healthy humans (age: 24–54 yr, median: 28 yr; 6 women and 9 men). Tilt table inclinations ranged from 15 to 90° and were varied in steps of 15°. All subjects underwent recordings at every step in random order. Heart period was assessed as the time difference between two consecutive R-wave peaks (RR) and the respiratory signal (R) as the sampling of the thoracic movement signal at the R-wave peaks. VRD was measured automatically as the temporal difference between the R-wave peak and T-wave apex (RTa) or T-wave end (RTe). The best model decomposed RT variability as due to RR changes (RR-related RT variability) to direct respiratory-related inputs (R-related RT variability) and to unknown rhythmical sources unrelated to RR changes and R (RR-R-unrelated RT variability). Using this model, RTe variability was found to be less predictable than RTa variability and composed of a smaller fraction of RR-related RT variability and a larger fraction of RR-R-unrelated RT variability. Predictability progressively decreased with tilt table angles, suggesting increased complexity of RT regulation. RT variance progressively increased with tilt table inclination. This increase was characterized by a gradual rise of the amount of RR-R-unrelated RT variability, whereas the amount of RR-related RT variability remained unchanged. These results suggest that the amount of RT variability, complexity of RT dynamics, and amount of RR-R-unrelated RT variability increase with the magnitude of the sympathetic drive directly related to tilt table inclination. We propose the utilization of the amount of RR-R-unrelated RT variability instead of overall RT variability as an indirect measure of autonomic regulation directed to ventricles.

Causal relationships between heart period and systolic arterial pressure during graded head-up tilt

2011 ◽  
Vol 300 (2) ◽  
pp. R378-R386 ◽  
Author(s):  
Alberto Porta ◽  
Aparecida M. Catai ◽  
Anielle C. M. Takahashi ◽  
Valentina Magagnin ◽  
Tito Bassani ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Causal Relation ◽  
Systolic Arterial Pressure ◽  
Causal Link ◽  
Heart Period ◽  
Reverse Causality ◽  
Tilt Table ◽  
Baroreflex Control ◽  
Healthy Humans ◽  
Head Up Tilt

In physiological conditions, heart period (HP) affects systolic arterial pressure (SAP) through diastolic runoff and Starling's law, but, the reverse relation also holds as a result of the continuous action of baroreflex control. The prevailing mechanism sets the dominant temporal direction in the HP-SAP interactions (i.e., causality). We exploited cross-conditional entropy to assess HP-SAP causality. A traditional approach based on phases was applied for comparison. The ability of the approach to detect the lack of causal link from SAP to HP was assessed on 8 short-term (STHT) and 11 long-term heart transplant (LTHT) recipients (i.e., less than and more than 2 yr after transplantation, respectively). In addition, spontaneous HP and SAP variabilities were extracted from 17 healthy humans (ages 21–36 yr, median age 29 yr; 9 females) at rest and during graded head-up tilt. The tilt table inclinations ranged from 15 to 75° and were changed in steps of 15°. All subjects underwent recordings at every step in random order. The approach detected the lack of causal relation from SAP to HP in STHT recipients and the gradual restoration of the causal link from SAP to HP with time after transplantation in the LTHT recipients. The head-up tilt protocol induced the progressive shift from the prevalent causal direction from HP to SAP to the reverse causality (i.e., from SAP to HP) with tilt table inclination in healthy subjects. Transformation of phases into time shifts and comparison with baroreflex latency supported this conclusion. The proposed approach is highly efficient because it does not require the knowledge of baroreflex latency. The dependence of causality on tilt table inclination suggests that “spontaneous” baroreflex sensitivity estimated using noncausal methods (e.g., spectral and cross-spectral approaches) is more reliable at the highest tilt table inclinations.

Temporal asymmetries of short-term heart period variability are linked to autonomic regulation

2008 ◽  
Vol 295 (2) ◽  
pp. R550-R557 ◽  
Author(s):  
A. Porta ◽  
K. R. Casali ◽  
A. G. Casali ◽  
T. Gnecchi-Ruscone ◽  
E. Tobaldini ◽  
...  
Keyword(s):  
Autonomic Regulation ◽  
Heart Period ◽  
Short Term ◽  
Time Reversibility ◽  
Heart Period Variability ◽  
Period Variability ◽  
Healthy Humans ◽  
Inclination Angles ◽  
Head Up Tilt ◽  
Important Shift

We exploit time reversibility analysis, checking the invariance of statistical features of a series after time reversal, to detect temporal asymmetries of short-term heart period variability series. Reversibility indexes were extracted from 22 healthy fetuses between 16th to 40th wk of gestation and from 17 healthy humans (aged 21 to 54, median = 28) during graded head-up tilt with table inclination angles randomly selected inside the set {15, 30, 45, 60, 75, 90}. Irreversibility analysis showed that nonlinear dynamics observed in short-term heart period variability are mostly due to asymmetric patterns characterized by bradycardic runs shorter than tachycardic ones. These temporal asymmetries were 1) more likely over short temporal scales than over longer, dominant ones; 2) more frequent during the late period of pregnancy (from 25th to 40th week of gestation); 3) significantly present in healthy humans at rest in supine position; 4) more numerous during 75 and 90° head-up tilt. Results suggest that asymmetric patterns observable in short-term heart period variability might be the result of a fully developed autonomic regulation and that an important shift of the sympathovagal balance toward sympathetic predominance (and vagal withdrawal) can increase their presence.

scholarly journals Prolongation of Electrocardiographic T Wave Parameters Recorded during the Head-Up Tilt Table Test as Independent Markers of Syncope Severity in Children

2020 ◽  
Vol 17 (18) ◽  
pp. 6441
Author(s):  
Grażyna Markiewicz-Łoskot ◽  
Ewelina Kolarczyk ◽  
Bogusław Mazurek ◽  
Marianna Łoskot ◽  
Lesław Szydłowski
Keyword(s):  
Vasovagal Syncope ◽  
The Other ◽  
Control Group ◽  
Tilt Table Test ◽  
Tilt Table ◽  
T Wave ◽  
Good Discriminator ◽  
Wave Morphology ◽  
Head Up Tilt ◽  
T Waves

The head-up tilt table test (HUTT) with the upright phase is used to help determine an imbalance of the sympathetic nervous system that is related to abnormal electrocardiographic repolarization in children with vasovagal syncope (VVS) and also in patients with the long QT syndrome (LQTS). The study attempted to evaluate T wave morphology and QT and TpTe (Tpeak–Tend) intervals recorded in ECG during the HUTT for a more accurate diagnosis of children with VVS. The group investigated 70 children with a negative HUTT result: 40 patients with VVS and 30 healthy volunteers without syncope. The RR interval as well as TpTe, and QTc intervals were measured in lead V5 of electrocardiogram (ECG) on admission to the hospital and during three phases of the HUTT. In syncopal children, which included 23 children with bifid or flat T waves and 17 patients with normal T waves in the upright phase, the QTc and TpTe were longer (p < 0.001) compared to the other test phases and longer (p < 0.001) than in the control group, respectively, with the risk of arrhythmias. Only in the control group, the TpTe was shorter (p < 0.001) in the upright phase than in the other tilt phases. The TpTe in the upright phase (>70 ms) was a good discriminator, and was better than the QTc (>427 ms). Prolongation of electrocardiographic TpTe and QT intervals, in addition to the (abnormal T wave morphology recorded during the HUTT, are helpful for identifying VVS children more predisposed to ventricular arrhythmias with a latent risk of LQTS. Further studies are required to assess the value of these repolarization parameters in clinical practice.

scholarly journals Correlation of head-up tilt table test time interval with risk of recurrent syncope

2015 ◽  
Vol 67 ◽  
pp. S77
Author(s):  
R.K. Gokhroo ◽  
Kumari Priti ◽  
A. Avinash ◽  
Bhanwar Lal Ranwa ◽  
Kamal Kishor ◽  
...  
Keyword(s):  
Test Time ◽  
Time Interval ◽  
Tilt Table Test ◽  
Tilt Table ◽  
Head Up Tilt

Repolarization disparity as a predictor of response to Head Up Tilt‐table Test in pediatric syncope

2021 ◽  
Author(s):  
Mohammad Reza Khalilian ◽  
Abdolrahim Ghasemi ◽  
Narges Khazaei ◽  
Sara Khoshkhou ◽  
Elham Mahmoudi
Keyword(s):  
Tilt Table Test ◽  
Tilt Table ◽  
Head Up Tilt

Impact of inspiratory threshold loading on brain activity and cognitive performances in healthy humans

2021 ◽  
Author(s):  
Jessica Taytard ◽  
Camille Gand ◽  
Marie-Cécile Niérat ◽  
Romain Barthes ◽  
Sophie Lavault ◽  
...  
Keyword(s):  
Working Memory ◽  
Cognitive Performance ◽  
Brain Activity ◽  
Random Order ◽  
Attentional Focus ◽  
Cortical Activation ◽  
Cognitive Interference ◽  
Cortical Networks ◽  
Healthy Humans ◽  
Serial Addition

In healthy humans, inspiratory threshold loading deteriorates cognitive performances. This can result from motor-cognitive interference (activation of motor respiratory-related cortical networks vs. executive resources allocation), sensory-cognitive interference (dyspnea vs. shift in attentional focus), or both. We hypothesized that inspiratory loading would concomitantly induce dyspnea, activate motor respiratory-related cortical networks, and deteriorate cognitive performance. We reasoned that a concomitant activation of cortical networks and cognitive deterioration would be compatible with motor-cognitive interference, particularly in case of a predominant alteration of executive cognitive performances. Symmetrically, we reasoned that a predominant alteration of attention-depending performances would suggest sensory-cognitive interference. Twenty-five volunteers (12 men; 19.5-51.5 years) performed the Paced Auditory Serial Addition test (PASAT-A and B; calculation capacity, working memory, attention), the Trail Making Test (TMT-A, visuospatial exploration capacity; TMT-B, visuospatial exploration capacity and attention), and the Corsi block-tapping test (visuospatial memory, short-term and working memory) during unloaded breathing and inspiratory threshold loading in random order. Loading consistently induced dyspnea and respiratory-related brain activation. It was associated with deteriorations inPASAT A (52 [45.5;55.5] (median [interquartile range]) to 48 [41;54.5], p=0.01), PASAT B (55 [47.5;58] to 51 [44.5;57.5], p=0.01), and TMT B (44s [36;54.5] to 53s [42;64], p=0.01), but did not affect TMT-A and Corsi. The concomitance of cortical activation and cognitive performance deterioration is compatible with competition for cortical resources (motor-cognitive interference), while the profile of cognitive impairment (PASAT and TMT-B but not TMT-A and Corsi) is compatible with a contribution of attentional distraction (sensory-cognitive interference). Both mechanisms are therefore likely at play.

scholarly journals Pulsed Wave Doppler Ultrasound Is Useful to Assess Vasomotor Response in Patients with Multiple System Atrophy and Well Correlated with Tilt Table Study

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Ke-Vin Chang ◽  
Wen-Shiang Chen ◽  
Ruey-Meei Wu ◽  
Ssu-Yuan Chen ◽  
Hsiu-Yu Shen ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Correlation Analysis ◽  
Multiple System Atrophy ◽  
Cardiovascular Response ◽  
Vasomotor Response ◽  
Tilt Table ◽  
Hemodynamic Variables ◽  
Pulsed Wave Doppler ◽  
Head Up Tilt

The study aim was to assess sympathetic vasomotor response (SVR) by using pulsed wave Doppler (PWD) ultrasound in patients with multiple system atrophy (MSA) and correlate with the tilt table study. We recruited 18 male patients and 10 healthy men as controls. The SVR of the radial artery was evaluated by PWD, using inspiratory cough as a provocative maneuver. The response to head-up tilt was studied by a tilt table with simultaneous heart rate and blood pressure recording. The hemodynamic variables were compared between groups, and were examined by correlation analysis. Regarding SVR, MSA patients exhibited a prolonged latency and less heart rate acceleration following inspiratory cough. Compared with the tilt table test, the elevation of heart rate upon SVR was positively correlated to the increase of heart rate after head-up tilt. The correlation analysis indicated that the magnitude of blood pressure drop from supine to upright was positively associated with the SVR latency but negatively correlated with the heart rate changes upon SVR. The present study demonstrated that blunted heart rate response might explain MSA's vulnerability to postural challenge. PWD may be used to predict cardiovascular response to orthostatic stress upon head-up tilt in MSA patients.

Exploring directionality in spontaneous heart period and systolic pressure variability interactions in humans: implications in the evaluation of baroreflex gain

2005 ◽  
Vol 288 (4) ◽  
pp. H1777-H1785 ◽  
Author(s):  
Giandomenico Nollo ◽  
Luca Faes ◽  
Alberto Porta ◽  
Renzo Antolini ◽  
Flavia Ravelli
Keyword(s):  
Spectral Analysis ◽  
Spectral Component ◽  
Systolic Pressure ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Phase Lag ◽  
Healthy Humans ◽  
Head Up Tilt ◽  
Causal Approach ◽  
Young Subjects

Although in physiological conditions RR interval and systolic arterial pressure (SAP) are likely to interact in a closed loop, the traditional cross-spectral analysis cannot distinguish feedback (FB) from feedforward (FF) influences. In this study, a causal approach was applied for calculating the coherence from SAP to RR ( Ks-r) and from RR to SAP ( Kr-s) and the gain and phase of the baroreflex transfer function. The method was applied, compared with the noncausal one, to RR and SAP series taken from 15 healthy young subjects in the supine position and after passive head-up tilt. For the low frequency (0.04–0.15 Hz) spectral component, the enhanced FF coupling ( Kr-s = 0.59 ± 0.21, significant in 14 subjects) and the blunted FB coupling ( Ks-r = 0.17 ± 0.17, significant in 4 subjects) found at rest indicated the prevalence of nonbaroreflex mechanisms. The tilt maneuver recovered FB influences ( Ks-r = 0.47 ± 0.16, significant in 14 subjects), which were stronger than FF interactions ( Ks-r = 0.34 ± 0.19, significant in 9 subjects). At the respiratory frequency, the RR-SAP regulation was balanced at rest ( Ks-r = 0.30 ± 0.18 and Kr-s = 0.29 ± 0.20, significant in 11 and 8 subjects) and shifted toward FB mechanisms after tilt ( Ks-r = 0.35 ± 0.19 and Kr-s = 0.19 ± 0.11, significant in 14 and 8 subjects). The causal baroreflex gain estimates were always lower than the corresponding noncausal values and decreased significantly from rest to tilt in both frequency bands. The tilt-induced increase of the phase lag from SAP to RR suggested a shift from vagal to sympathetic modulation. Thus the importance of nonbaroreflex interactions pointed out the necessity of accounting for causality in the cross-spectral analysis of the interactions between cardiovascular variables in healthy humans.

scholarly journals The Repolarization Period during the Head-Up Tilt Test in Children with Vasovagal Syncope

2020 ◽  
Vol 17 (6) ◽  
pp. 1908 ◽  
Author(s):  
Ewelina Kolarczyk ◽  
Grażyna Markiewicz-Łoskot ◽  
Lesław Szydłowski
Keyword(s):  
Vasovagal Syncope ◽  
Clinical Importance ◽  
Clinical Work ◽  
Ventricular Repolarization ◽  
Tilt Test ◽  
Wave Refraction ◽  
T Wave ◽  
Prolonged Duration ◽  
Head Up Tilt ◽  
Head Up Tilt Test

Background: Electrocardiography (ECG) and the head-up tilt test (HUTT) are vital in clinical work-up in children with vasovagal syncope (VVS). Ventricular repolarization parameters (QT) measured during the HUTT can be indicative of electrical instability; however, these parameters are not frequently assessed. This study aimed to investigate if ventricular repolarization parameters measured during the HUTT could be indicative of future ventricular arrhythmias in children with syncope. Methods: The shape and amplitude of the T-wave and parameters of the repolarization period (QT, QTpeak, Tpeak-Tend) were evaluated in a resting ECG performed on the first day of hospitalization and in ECGs performed during three phases of the HUTT. Results: In the after-tilt phase of the HUTT, 19/30 children displayed a change in T-wave morphology. QTc was significantly longer in VVS I compared to that in VVS II patients, but not in the controls (p = 0.092). Conclusions: We need further follow-up studies to establish the clinical importance of abnormal dynamics of the repolarization period in children with VVS and negative HUTT. Therefore, children with abnormal T-wave refraction and prolonged duration of the TpTe should remain under the care of a cardiological outpatient.

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