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Kouhyar Tavakolian - One of the best experts on this subject based on the ideXlab platform.

  • Skeletal Muscle Pump Drives Control of Cardiovascular and Postural Systems
    Scientific Reports, 2017
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Da Xu, Michelle Bruner, Kouhyar Tavakolian
    Abstract:

    The causal interaction between cardio-postural-musculoskeletal systems is critical in maintaining postural stability under orthostatic challenge. The absence or reduction of such interactions could lead to fainting and falls often experienced by elderly individuals. The causal relationship between systolic blood pressure (SBP), calf electromyography (EMG), and resultant center of pressure (COPr) can quantify the behavior of cardio-postural control loop. Convergent cross mapping (CCM) is a non-linear approach to establish causality, thus, expected to decipher nonlinear causal cardio-postural-musculoskeletal interactions. Data were acquired simultaneously from young participants (25 ± 2 years, n = 18) during a 10-minute sit-to-stand test. In the young population, skeletal muscle Pump was found to drive blood pressure control (EMG → SBP) as well as control the postural sway (EMG → COPr) through the significantly higher causal drive in the direction towards SBP and COPr. Furthermore, the effect of aging on muscle Pump activation associated with blood pressure regulation was explored. Simultaneous EMG and SBP were acquired from elderly group (69 ± 4 years, n = 14). A significant (p = 0.002) decline in EMG → SBP causality was observed in the elderly group, compared to the young group. The results highlight the potential of causality to detect alteration in blood pressure regulation with age, thus, a potential clinical utility towards detection of fall proneness.

  • CinC - Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    2016 Computing in Cardiology Conference (CinC), 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, Da Xu, Nandu Goswami, Kouhyar Tavakolian
    Abstract:

    Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p

  • EMBC - Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    Computing in Cardiology, 2016
    Co-Authors: A. K. Verma, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, A. Garg, Nithyagopal Goswami, D. Xu, Kouhyar Tavakolian
    Abstract:

    © 2016 CCAL. Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p < 0.05). Although arterial baroreflex was not different between groups, elevated drive from SBP to EMG activity suggests a potential compensatory action by the baroreflex-mediated muscle Pump activation towards blood pressure regulation following stroke.

Andrew P. Blaber - One of the best experts on this subject based on the ideXlab platform.

  • Skeletal Muscle Pump Drives Control of Cardiovascular and Postural Systems
    Scientific Reports, 2017
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Da Xu, Michelle Bruner, Kouhyar Tavakolian
    Abstract:

    The causal interaction between cardio-postural-musculoskeletal systems is critical in maintaining postural stability under orthostatic challenge. The absence or reduction of such interactions could lead to fainting and falls often experienced by elderly individuals. The causal relationship between systolic blood pressure (SBP), calf electromyography (EMG), and resultant center of pressure (COPr) can quantify the behavior of cardio-postural control loop. Convergent cross mapping (CCM) is a non-linear approach to establish causality, thus, expected to decipher nonlinear causal cardio-postural-musculoskeletal interactions. Data were acquired simultaneously from young participants (25 ± 2 years, n = 18) during a 10-minute sit-to-stand test. In the young population, skeletal muscle Pump was found to drive blood pressure control (EMG → SBP) as well as control the postural sway (EMG → COPr) through the significantly higher causal drive in the direction towards SBP and COPr. Furthermore, the effect of aging on muscle Pump activation associated with blood pressure regulation was explored. Simultaneous EMG and SBP were acquired from elderly group (69 ± 4 years, n = 14). A significant (p = 0.002) decline in EMG → SBP causality was observed in the elderly group, compared to the young group. The results highlight the potential of causality to detect alteration in blood pressure regulation with age, thus, a potential clinical utility towards detection of fall proneness.

  • CinC - Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    2016 Computing in Cardiology Conference (CinC), 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, Da Xu, Nandu Goswami, Kouhyar Tavakolian
    Abstract:

    Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p

  • EMBC - Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    Computing in Cardiology, 2016
    Co-Authors: A. K. Verma, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, A. Garg, Nithyagopal Goswami, D. Xu, Kouhyar Tavakolian
    Abstract:

    © 2016 CCAL. Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p < 0.05). Although arterial baroreflex was not different between groups, elevated drive from SBP to EMG activity suggests a potential compensatory action by the baroreflex-mediated muscle Pump activation towards blood pressure regulation following stroke.

S F Figoni - One of the best experts on this subject based on the ideXlab platform.

  • Electrical stimulation-induced contraction to reduce blood stasis during arthroplasty
    IEEE Transactions on Rehabilitation Engineering, 1997
    Co-Authors: P. D. Faghri, H. F. Pompe Van Meerdervort, R. M. Glaser, S F Figoni
    Abstract:

    Deep venous thrombosis and subsequent pulmonary embolism due to venous pooling/stasis commonly occur in patients during hip and/or knee arthroplasty (i.e., replacement). This problem may be alleviated by using techniques to promote lower limb blood flow. Electrical stimulation-induced contractions have been shown to activate the skeletal muscle Pump, promote limb blood flow, and may be effective for reducing venous pooling/stasis and edema. Therefore, electrical stimulation may reduce the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) during and following surgery. The overall goal of this project was to evaluate the clinical efficacy of sequential electrical stimulation-induced leg muscle contractions on the venous blood flow during surgery. The degree of venous pooling/stasis was monitored via electrical impedance changes in the thorax. The changes in the patient's central hemodynamics were then calculated. Thirty patients were recruited and randomly assigned to either a control group (n = 15, mean age = 66.4 +/- 7.3) or experimental group (n = 15, age = 60.7 +/- 9.7). Both groups received the standard medical treatment for prevention of DVT (i.e., coumadin, heparin, etc.) and compression stockings (TED, Kendall). The control group used the sequential compression device (SCD + TED) and the experimental group used electrical stimulation (ES + TED). Electrical stimulation was applied via surface electrodes to the lower-limb muscles (tibialis anterior and gastrocnemius) and upper limb muscles (quadriceps femoris and hamstrings). These muscles contracted sequentially, using an eight-channel electrical stimulator. Four seconds of calf (contraction/compression) were followed by 7-s of calf and thigh (contraction/compression) interspersed by 60-s rest period during both electrical stimulation or sequential compression device. This cycle continued throughout the surgery (60-75 min) for both groups. At 15 min intervals, venous return was monitored by impedance cardiograph. Physiologic responses including ventricular stroke volume (SV), cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), as well as mean arterial pressure (MAP) were monitored. These responses were statistically analyzed and compared throughout the surgery within each group and between the two groups. The results show stroke volume and cardiac output to be higher throughout surgery in the electrical stimulation group as compared with the sequential compression device group. The heart rate was consistently lower during electrical stimulation for both groups. Total peripheral resistance did not change in the electrical stimulation group; but increased in the sequential compression device group. The data suggest that continuous electrical stimulation-induced contractions could improve lower leg circulation by eliciting the physiologic muscle Pump. This will lead to improved venous circulation and reduction of blood stasis during total hip and/or knee surgery. This technique may offer greater protection against DVT and PE during surgery than the commonly used sequential compression device.

  • Electrical stimulation-induced contraction to reduce blood stasis during arthroplasty
    IEEE Transactions on Rehabilitation Engineering, 1997
    Co-Authors: P. D. Faghri, R. M. Glaser, H.f. Pompe Van Meerdervort, S F Figoni
    Abstract:

    Deep venous thrombosis and subsequent pulmonary embolism due to venous pooling/stasis commonly occur in patients during hip and/or knee arthroplasty (i.e., replacement). This problem may be alleviated by using techniques to promote lower limb blood flow. Electrical stimulation-induced contractions have been shown to activate the skeletal muscle Pump, promote limb blood flow, and may be effective for reducing venous pooling/stasis and edema. Therefore, electrical stimulation may reduce the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) during and following surgery. The overall goal of this project was to evaluate the clinical efficacy of sequential electrical stimulation-induced leg muscle contractions on the venous blood flow during surgery. The degree of venous pooling/stasis was monitored via electrical impedance changes in the thorax. The changes in the patient's central hemodynamics were then calculated. Thirty patients were recruited and randomly assigned to either a control group (n=15, mean age=66.4/spl plusmn/7.3) or experimental group (n=15, age 60.7/spl plusmn/9.7). Both groups received the standard medical treatment for prevention of DVT (i.e., coumadin, heparin, etc.) and compression stockings (TED, Kendall). The control group used the sequential compression device (SCD+TED) and the experimental group used electrical stimulation (ES+TED). Electrical stimulation was applied via surface electrodes to the lower-limb muscles (tibialis anterior and gastrocnemius) and upper limb muscles (quadriceps femoris and hamstrings). These muscles contracted sequentially, using an 8-channel electrical stimulator. Four seconds of calf (contraction/compression) were followed by 7-s of calf and thigh (contraction/compression) interspersed by 60-s rest period during both electrical stimulation or sequential compression device. This cycle continued throughout the surgery (60-75 min) for both groups. At 15 min intervals, venous return was monitored by impedance cardiograph. Physiologic responses including ventricular stroke volume (SV), cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), as well as mean arterial pressure (MAP) were monitored. These responses were statistically analyzed and compared throughout the surgery within each group and between the 2 groups. The results show stroke volume and cardiac output to be higher throughout surgery in the electrical stimulation group as compared with the sequential compression device group. The heart rate was consistently lower during electrical stimulation for both groups. Total peripheral resistance did not change in the electrical stimulation group; but increased in the sequential compression device group.

Amanmeet Garg - One of the best experts on this subject based on the ideXlab platform.

  • Skeletal Muscle Pump Drives Control of Cardiovascular and Postural Systems
    Scientific Reports, 2017
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Da Xu, Michelle Bruner, Kouhyar Tavakolian
    Abstract:

    The causal interaction between cardio-postural-musculoskeletal systems is critical in maintaining postural stability under orthostatic challenge. The absence or reduction of such interactions could lead to fainting and falls often experienced by elderly individuals. The causal relationship between systolic blood pressure (SBP), calf electromyography (EMG), and resultant center of pressure (COPr) can quantify the behavior of cardio-postural control loop. Convergent cross mapping (CCM) is a non-linear approach to establish causality, thus, expected to decipher nonlinear causal cardio-postural-musculoskeletal interactions. Data were acquired simultaneously from young participants (25 ± 2 years, n = 18) during a 10-minute sit-to-stand test. In the young population, skeletal muscle Pump was found to drive blood pressure control (EMG → SBP) as well as control the postural sway (EMG → COPr) through the significantly higher causal drive in the direction towards SBP and COPr. Furthermore, the effect of aging on muscle Pump activation associated with blood pressure regulation was explored. Simultaneous EMG and SBP were acquired from elderly group (69 ± 4 years, n = 14). A significant (p = 0.002) decline in EMG → SBP causality was observed in the elderly group, compared to the young group. The results highlight the potential of causality to detect alteration in blood pressure regulation with age, thus, a potential clinical utility towards detection of fall proneness.

  • CinC - Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    2016 Computing in Cardiology Conference (CinC), 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, Da Xu, Nandu Goswami, Kouhyar Tavakolian
    Abstract:

    Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p

  • EMBC - Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • EMBC - Posture muscle relationship with cardiovascular changes under orthostatic challenge.
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2014
    Co-Authors: Amanmeet Garg, Da Xu, Andrew P. Blaber
    Abstract:

    Lower leg muscles are known to be activated during standing. On the other hand, standing is known to induce orthostatic stress. Our recent work presented that the posture control and cardiovascular systems are related to each other. However, the relationship of the individual muscle activation with blood pressure changes is not fully understood. The present preliminary study conducted experiments to collect data for muscle activation (EMG) and blood pressure (BP) changes during quiet standing. High coherence (>threshold) values observed between the EMG and BP signals suggest a strong relationship between the two. Additionally, the results of the study suggest a compensatory relationship of different lower leg muscles with blood pressure changes during quiet standing. I. INTRODUCTION Activation of skeletal muscles in the lower limbs (skeletal muscle Pump), such as through postural shifts, walking or running, increases venous return by Pumping blood collect- ing in the veins back to the heart (1). The maintenance of upright posture not only requires coordinated neuromuscular control of postural muscles (2), but also cardiovascular re- flexes to maintain blood pressure (BP). It has been shown that different muscles in the lower leg (below knee) are activated during quiet standing (3). Among these the medial and lateral gastrocnemius group has been shown to be associated with the skeletal muscle Pump (1) while, the gastrocnemius group along with the soleus and tibialis anterior are related to posture control (2), (3). It is possible that different muscles in the same leg relate differently with the BP changes. Spectral analysis of the characteristic signals for these sys- tems gets inadequate treatment by use of methods assuming stationarity of the signals. The use of methods accounting for non-stationary nature of signals is necessary. Wavelet methods have already been used to analyze non-stationary EMG signals (4), (5) and BP signals (6) and the two together (7), (8). The wavelet transform coherence (WTC) method has been applied in geophysics (9), neuroscience methods (10) and cardio-postural investigations (7), (8) and provides time-frequency analysis of dependence between two signals without assuming signal stationarity.

Ajay K. Verma - One of the best experts on this subject based on the ideXlab platform.

  • Skeletal Muscle Pump Drives Control of Cardiovascular and Postural Systems
    Scientific Reports, 2017
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Da Xu, Michelle Bruner, Kouhyar Tavakolian
    Abstract:

    The causal interaction between cardio-postural-musculoskeletal systems is critical in maintaining postural stability under orthostatic challenge. The absence or reduction of such interactions could lead to fainting and falls often experienced by elderly individuals. The causal relationship between systolic blood pressure (SBP), calf electromyography (EMG), and resultant center of pressure (COPr) can quantify the behavior of cardio-postural control loop. Convergent cross mapping (CCM) is a non-linear approach to establish causality, thus, expected to decipher nonlinear causal cardio-postural-musculoskeletal interactions. Data were acquired simultaneously from young participants (25 ± 2 years, n = 18) during a 10-minute sit-to-stand test. In the young population, skeletal muscle Pump was found to drive blood pressure control (EMG → SBP) as well as control the postural sway (EMG → COPr) through the significantly higher causal drive in the direction towards SBP and COPr. Furthermore, the effect of aging on muscle Pump activation associated with blood pressure regulation was explored. Simultaneous EMG and SBP were acquired from elderly group (69 ± 4 years, n = 14). A significant (p = 0.002) decline in EMG → SBP causality was observed in the elderly group, compared to the young group. The results highlight the potential of causality to detect alteration in blood pressure regulation with age, thus, a potential clinical utility towards detection of fall proneness.

  • CinC - Increased systolic blood pressure driven skeletal muscle activation following stroke: A causality study
    2016 Computing in Cardiology Conference (CinC), 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, F. Fazekas, Reza Fazel-rezai, Andrea Rössler, Da Xu, Nandu Goswami, Kouhyar Tavakolian
    Abstract:

    Older individuals following stroke have a higher incidence of orthostatic hypotension, syncope and fall risk. Thus, in a pilot study, we investigated the relationship between the arterial and skeletal muscle Pump baroreflexes in 8 older (63 ± 4 years) stroke patients (208 ± 14 days post-insult) and 8 age-matched healthy controls (62 ± 7 years) during quiet standing. Simultaneous continuous non-invasive lower leg muscle activity, electromyography (EMG), 3-lead electrocardiogram (ECG) and blood pressure were recorded continuously during the 5-minute stand portion of a sit-to-stand test. Causality was analyzed between EMG and systolic blood pressure (SBP) in the last 4 minutes of standing. Data were segmented into a time window of 45 seconds, translated with an overlap of 5 seconds on the entire 4-minute data. Convergent cross mapping (CCM) was used for studying the causality between the blood pressure and EMG signals. Spontaneous baroreflex sensitivity (BRS) was calculated using the sequence method. Between the two groups, there was no difference in spontaneous BRS (stroke: 4.85±1.52 ms/mmHg; control: 4.27±1.68 ms/mmHg; p=0.48) or causality from EMG towards SBP (stroke: 0.62±0.15; control: 0.67±0.05, p=0.38). The causal relationship from SBP to EMG was greater in stroke patients (0.48±0.05) compared to controls (0.41±0.05, p

  • EMBC - Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).

  • Analysis of causal cardio-postural interaction under orthostatic stress using convergent cross mapping
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS, 2016
    Co-Authors: Ajay K. Verma, Amanmeet Garg, Andrew P. Blaber, Reza Fazel-rezai, Kouhyar Tavakolian
    Abstract:

    Knowledge of a cause-and-effect relationship between different physiological systems is helpful in predicting their performance under perturbations, such as orthostatic challenge. The causal coupling between representative signals of the cardiovascular and postural systems under orthostatic challenge remains unknown. Understanding the causal relationship between these two systems is critical, as their interplay is vital to maintain stable upright posture of the human body during quiet standing. In this research, convergent cross mapping (CCM) method was applied to study the causal relationship between the cardiovascular and postural systems previously shown to have coherent activity during quiet standing. Causality was studied between Systolic blood pressure (SBP)-EMG (calf muscles), EMG-COPr (resultant center of pressure), and COPr-SBP signal pairs. These signals were simultaneously recorded in a 5-minute sit-to-stand test from five young healthy participants. Strength of causality was obtained between the signal pairs in a 30-second time segments. The results from this study indicate that there exists a bidirectional causal relationship between the cardio-postural signal pairs, indicating a system level interaction to counter perturbation due to orthostatic challenge. Skeletal muscle Pump was found to be driving control of SBP and COPr as the value of EMG→SBP (0.54±0.09) and EMG→COPr (0.52±0.07) were higher than the reverse causality of SBP→EMG (0.19±0.16) and COPr→EMG (0.29±0.16).