The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Marek Belohlavek - One of the best experts on this subject based on the ideXlab platform.
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left ventricular isovolumic flow sequence during sinus and paced rhythms new insights from use of high resolution doppler and ultrasonic digital particle imaging velocimetry
Journal of the American College of Cardiology, 2007Co-Authors: Partho P Sengupta, Bijoy K Khandheria, Josef Korinek, Arshad Jahangir, Shiro Yoshifuku, Ilija Milosevic, Marek BelohlavekAbstract:Objectives We sought to clarify the role of isovolumic intervals during a cardiac cycle by in vivo visualization of left ventricular (LV) intracavitary flow dynamics. Background Asynchronous LV deformation during isovolumic contraction (IVC) and isovolumic relaxation (IVR) might represent a transient feature of myocardial wall mechanics that reverses the direction of blood flow. Methods In 10 beating porcine hearts, the changes in LV intracavitary flow were recorded at baseline and after LV epicardial and right atrial pacing with high-resolution Doppler and contrast echocardiography. Two-dimensional vector flow fields were generated offline from B-mode contrast images with particle imaging velocimetry. Results During IVC, flow from the LV apex accelerated toward the base, whereas blood from the base was redirected toward the outflow through formation of an anterior vortex. Conversely, during IVR, flow was initially directed toward the apex and then briefly reversed toward the base. Epicardial pacing from the LV base altered the stages of flow redirection during the Pre-Ejection Period and delayed mitral valve closure (28 ± 14 ms vs. 61 ± 13 ms, p Conclusions Isovolumic intervals are not Periods of hemodynamic stasis but, rather, phases with dynamic changes in intracavitary flow. Experimentally induced aberrant epicardial electrical activation alters stages of flow redirection and prolongs the Pre-Ejection Period. Normal electromechanical activation through the His-Purkinje system in mammalian hearts maintains an inherent synchrony with the sequence of intracavitary flow redirection.
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left ventricular isovolumic flow sequence during sinus and paced rhythms new insights from use of high resolution doppler and ultrasonic digital particle imaging velocimetry
Journal of the American College of Cardiology, 2007Co-Authors: Partho P Sengupta, Bijoy K Khandheria, Josef Korinek, Arshad Jahangir, Shiro Yoshifuku, Ilija Milosevic, Marek BelohlavekAbstract:Objectives We sought to clarify the role of isovolumic intervals during a cardiac cycle by in vivo visualization of left ventricular (LV) intracavitary flow dynamics. Background Asynchronous LV deformation during isovolumic contraction (IVC) and isovolumic relaxation (IVR) might represent a transient feature of myocardial wall mechanics that reverses the direction of blood flow. Methods In 10 beating porcine hearts, the changes in LV intracavitary flow were recorded at baseline and after LV epicardial and right atrial pacing with high-resolution Doppler and contrast echocardiography. Two-dimensional vector flow fields were generated offline from B-mode contrast images with particle imaging velocimetry. Results During IVC, flow from the LV apex accelerated toward the base, whereas blood from the base was redirected toward the outflow through formation of an anterior vortex. Conversely, during IVR, flow was initially directed toward the apex and then briefly reversed toward the base. Epicardial pacing from the LV base altered the stages of flow redirection during the Pre-Ejection Period and delayed mitral valve closure (28 ± 14 ms vs. 61 ± 13 ms, p Conclusions Isovolumic intervals are not Periods of hemodynamic stasis but, rather, phases with dynamic changes in intracavitary flow. Experimentally induced aberrant epicardial electrical activation alters stages of flow redirection and prolongs the Pre-Ejection Period. Normal electromechanical activation through the His-Purkinje system in mammalian hearts maintains an inherent synchrony with the sequence of intracavitary flow redirection.
Partho P Sengupta - One of the best experts on this subject based on the ideXlab platform.
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left ventricular isovolumic flow sequence during sinus and paced rhythms new insights from use of high resolution doppler and ultrasonic digital particle imaging velocimetry
Journal of the American College of Cardiology, 2007Co-Authors: Partho P Sengupta, Bijoy K Khandheria, Josef Korinek, Arshad Jahangir, Shiro Yoshifuku, Ilija Milosevic, Marek BelohlavekAbstract:Objectives We sought to clarify the role of isovolumic intervals during a cardiac cycle by in vivo visualization of left ventricular (LV) intracavitary flow dynamics. Background Asynchronous LV deformation during isovolumic contraction (IVC) and isovolumic relaxation (IVR) might represent a transient feature of myocardial wall mechanics that reverses the direction of blood flow. Methods In 10 beating porcine hearts, the changes in LV intracavitary flow were recorded at baseline and after LV epicardial and right atrial pacing with high-resolution Doppler and contrast echocardiography. Two-dimensional vector flow fields were generated offline from B-mode contrast images with particle imaging velocimetry. Results During IVC, flow from the LV apex accelerated toward the base, whereas blood from the base was redirected toward the outflow through formation of an anterior vortex. Conversely, during IVR, flow was initially directed toward the apex and then briefly reversed toward the base. Epicardial pacing from the LV base altered the stages of flow redirection during the Pre-Ejection Period and delayed mitral valve closure (28 ± 14 ms vs. 61 ± 13 ms, p Conclusions Isovolumic intervals are not Periods of hemodynamic stasis but, rather, phases with dynamic changes in intracavitary flow. Experimentally induced aberrant epicardial electrical activation alters stages of flow redirection and prolongs the Pre-Ejection Period. Normal electromechanical activation through the His-Purkinje system in mammalian hearts maintains an inherent synchrony with the sequence of intracavitary flow redirection.
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left ventricular isovolumic flow sequence during sinus and paced rhythms new insights from use of high resolution doppler and ultrasonic digital particle imaging velocimetry
Journal of the American College of Cardiology, 2007Co-Authors: Partho P Sengupta, Bijoy K Khandheria, Josef Korinek, Arshad Jahangir, Shiro Yoshifuku, Ilija Milosevic, Marek BelohlavekAbstract:Objectives We sought to clarify the role of isovolumic intervals during a cardiac cycle by in vivo visualization of left ventricular (LV) intracavitary flow dynamics. Background Asynchronous LV deformation during isovolumic contraction (IVC) and isovolumic relaxation (IVR) might represent a transient feature of myocardial wall mechanics that reverses the direction of blood flow. Methods In 10 beating porcine hearts, the changes in LV intracavitary flow were recorded at baseline and after LV epicardial and right atrial pacing with high-resolution Doppler and contrast echocardiography. Two-dimensional vector flow fields were generated offline from B-mode contrast images with particle imaging velocimetry. Results During IVC, flow from the LV apex accelerated toward the base, whereas blood from the base was redirected toward the outflow through formation of an anterior vortex. Conversely, during IVR, flow was initially directed toward the apex and then briefly reversed toward the base. Epicardial pacing from the LV base altered the stages of flow redirection during the Pre-Ejection Period and delayed mitral valve closure (28 ± 14 ms vs. 61 ± 13 ms, p Conclusions Isovolumic intervals are not Periods of hemodynamic stasis but, rather, phases with dynamic changes in intracavitary flow. Experimentally induced aberrant epicardial electrical activation alters stages of flow redirection and prolongs the Pre-Ejection Period. Normal electromechanical activation through the His-Purkinje system in mammalian hearts maintains an inherent synchrony with the sequence of intracavitary flow redirection.
Wendy Berry Mendes - One of the best experts on this subject based on the ideXlab platform.
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correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks
International Journal of Psychophysiology, 2021Co-Authors: David G Weissman, Wendy Berry MendesAbstract:Abstract Autonomic nervous system (ANS) activity is a core and central component of emotion and motivated action. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and Pre-Ejection Period (PEP), respectively. Samples combined four previous studies (N = 325, 63% female, aged 15–55) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modelled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former groups.
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correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks
bioRxiv, 2020Co-Authors: David G Weissman, Wendy Berry MendesAbstract:Abstract Autonomic nervous system (ANS) activity is a core and central component of emotion. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and Pre-Ejection Period (PEP), respectively. Samples combined four previous studies (N=325) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modeled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled, perhaps reflecting shared regulatory mechanisms in the brain. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former group.
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patterns and individual differences in the coordination of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks
bioRxiv, 2019Co-Authors: David G Weissman, Wendy Berry MendesAbstract:Autonomic nervous system (ANS) activity is a core and central component of emotion. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and Pre-Ejection Period (PEP), respectively. Samples combined four previous studies (N=325) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modeled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled, perhaps reflecting shared regulatory mechanisms in the brain. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former group.
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patterns and individual differences in the coordination of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks
bioRxiv, 2019Co-Authors: David G Weissman, Wendy Berry MendesAbstract:Autonomic nervous system (ANS) activity is a core and central component of emotion. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and Pre-Ejection Period (PEP), respectively. Samples combined four previous studies (N=325) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modeled in order to determine the extent to which SNS and PNS activity is coordinated at rest, in response to a stressor, and during recovery, and whether this coordination was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled within task Periods, perhaps reflecting shared regulatory mechanisms in the brain, independent of reciprocal responses to environmental demands. However, recovery from a stressor was characterized by uncorrelated activity and coactivation on average. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, perhaps reflecting a greater range of physiological responding in the former group.
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anxiety depressive symptoms and cardiac autonomic function in perimenopausal and postmenopausal women with hot flashes a brief report
Menopause, 2018Co-Authors: Wendy Berry Mendes, Carolyn J Gibson, Michael Schembri, Alison J HuangAbstract:Author(s): Fu, Polly; Gibson, Carolyn J; Mendes, Wendy Berry; Schembri, Michael; Huang, Alison J | Abstract: ObjectiveThe aim of the study was to examine whether anxiety and depressive symptoms are associated with an adverse cardiac autonomic profile among midlife women with hot flashes.MethodsAnxiety and depressive symptoms were evaluated by validated self-administered questionnaires among peri- and postmenopausal women in a randomized trial of slow-paced respiration for hot flashes. Pre-Ejection Period (PEP), a marker of sympathetic activation, and respiratory sinus arrhythmia (RSA), a marker of parasympathetic activation, were measured at baseline and 12 weeks using impedance cardiography and electocardiography. Multivariable repeated measures linear regression models examined associations between anxiety and depression symptoms and autonomic markers, corrected for multiple comparisons with Benjamini-Hochberg procedure, and adjusted for age and body mass index.ResultsAmong the 121 participants, greater state anxiety was associated with shorter PEP, reflecting higher sympathetic activity (β = -0.24, P = 0.02). Greater trait anxiety and cognitive anxiety were associated with lower RSA, reflecting decreased parasympathetic activity (β = -0.03, P l 0.01 for Spielberger Trait Anxiety; β = -0.06, P = 0.02 for Hospital Anxiety and Depression Scale [HADS] Anxiety Subscale). Greater depressive symptoms were associated with lower RSA (β = -0.06, P = 0.03 for HADS Depression Subscale; β = -0.03, P = 0.04 for Beck Depression Inventory).ConclusionsAmong peri- and postmenopausal women with hot flashes, greater self-reported anxiety and depressive symptoms were associated with lower levels of resting cardiac parasympathetic activity, and greater state anxiety was associated with higher levels of cardiac sympathetic activity. Findings suggest that midlife women with increased anxiety and depressive symptoms may have an unfavorable cardiac autonomic profile with potential implications for their overall cardiovascular risk.
Nigel H Lovell - One of the best experts on this subject based on the ideXlab platform.
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change in pulse transit time and pre ejection Period during head up tilt induced progressive central hypovolaemia
Journal of Clinical Monitoring and Computing, 2007Co-Authors: Gregory S H Chan, Paul M Middleton, Branko G Celler, Lu Wang, Nigel H LovellAbstract:Objective Traditional vital signs such as heart rate (HR) and blood pressure (BP) are often regarded as insensitive markers of mild to moderate blood loss. The present study investigated the feasibility of using pulse transit time (PTT) to track variations in Pre-Ejection Period (PEP) during progressive central hypovolaemia induced by head-up tilt and evaluated the potential of PTT as an early non-invasive indicator of blood loss.
Agnes E Van Den Berg - One of the best experts on this subject based on the ideXlab platform.
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autonomic nervous system responses to viewing green and built settings differentiating between sympathetic and parasympathetic activity
International Journal of Environmental Research and Public Health, 2015Co-Authors: Magdalena Van Den Berg, Jolanda Maas, Rianne Muller, Anoek Braun, Wendy Kaandorp, Rene Van Lien, Mireille N M Van Poppel, Willem Van Mechelen, Agnes E Van Den BergAbstract:This laboratory study explored buffering and recovery effects of viewing urban green and built spaces on autonomic nervous system activity. Forty-six students viewed photos of green and built spaces immediately following, and preceding acute stress induction. Simultaneously recorded electrocardiogram and impedance cardiogram signal was used to derive respiratory sinus arrhythmia (RSA) and Pre-Ejection Period (PEP), indicators of respectively parasympathetic and sympathetic activity. The findings provide support for greater recovery after viewing green scenes, as marked by a stronger increase in RSA as a marker of parasympathetic activity. There were no indications for greater recovery after viewing green scenes in PEP as a marker of sympathetic activity, and there were also no indications of greater buffering effects of green space in neither RSA nor PEP. Overall, our findings are consistent with a predominant role of the parasympathetic nervous system in restorative effects of viewing green space.