Dynamical Assessment of Cerebral Autoregulation

Summary

Principal Investigator: Vera Novak
Abstract: [unreadable] DESCRIPTION (provided by applicant): Cerebral autoregulation that maintains perfusion in response to fluctuations of systemic blood pressure (BP) is lost post-stroke and traumatic brain injury (TBI). Noninvasive bedside methods are urgently needed to identify people with impaired autoregulation who may be at increased risk for stroke and adverse outcomes. The phase I goals are: 1) To develop and optimize the multimodal pressure flow (MMPF) method, a new approach to quantify cerebral autoregulation from nonstationary blood pressure (BP) and cerebral blood flow velocity (BFV) fluctuations using transcranial Doppler ultrasound. The major breakthrough is that the MMPF now allows measurement of instantaneous BP and BFV phase relationships over longer time period from spontaneous fluctuations under resting conditions. We will apply the MMPF method to the assessment of dynamic autoregulation using the instantaneous BP-BFV phase relationships during supine resting condition, and during the Valsalva maneuver and the sit-to-stand test. The MMPF analysis decomposes complex BP and BFV signals into empirical modes, representing their instantaneous frequency-amplitude modulation. Instantaneous BP-BFV phase relationships will be used as a measure of dynamical autoregulation. 2) To validate autoregulation measurements derived from the MMPF using BP-BFV responses to these physiological maneuvers, and to compare them to standard autoregulation indices obtained in populations of 118 healthy, 75 hypertensive, 30 diabetic and 50 stroke subjects. 3) To validate MMPF measurements using invasive measurements of intraarterial pressure (ABP), intracranial (ICP) and cerebral perfusion pressure (CPP=ABP-ICP) and BFV in 30 patients with traumatic brain injury, using existing databases from the Syncope and Falls laboratory (SAFE) at the Beth Israel Deaconess Medical Center and from the University of Cambridge. The assessment of cerebral autoregulation is of vital importance in many areas of clinical and investigative medicine. Therefore, in Phase II we plan to incorporate the MMPF software into existing transcranial Doppler systems in order to provide a new, widely applicable, practical tool for evaluation of cerebral autoregulation in clinical settings. The analysis technique developed by this project may help early detection of subjects at high risk of stroke. The quantitative measurements derived from this innovative technology can also serve as indices for monitoring post-stroke patients. Therefore, this project may have substantial socioeconomic impact. [unreadable] [unreadable] [unreadable]
Funding Period: 2007-03-15 - 2008-02-28
more information: NIH RePORT

Top Publications

  1. pmc Impaired cerebral autoregulation is associated with brain atrophy and worse functional status in chronic ischemic stroke
    Mikio C Aoi
    Biomathematics Program, Department of Mathematics, North Carolina State University, Raleigh, NC, USA
    PLoS ONE 7:e46794. 2012
  2. pmc Nonlinear assessment of cerebral autoregulation from spontaneous blood pressure and cerebral blood flow fluctuations
    Kun Hu
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, 812 Stoneman Bldg, 330 Brookline Avenue, Boston, MA 02115, USA
    Cardiovasc Eng 8:60-71. 2008
  3. pmc Hypertension and cerebral vasoreactivity: a continuous arterial spin labeling magnetic resonance imaging study
    Ihab Hajjar
    Harvard Medical School, Institute for Aging Research Hebrew SeniorLife, Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, MA 02131, USA
    Hypertension 56:859-64. 2010
  4. pmc Association of blood pressure elevation and nocturnal dipping with brain atrophy, perfusion and functional measures in stroke and nonstroke individuals
    Ihab Hajjar
    Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
    Am J Hypertens 23:17-23. 2010
  5. pmc Cerebral flow velocities during daily activities depend on blood pressure in patients with chronic ischemic infarctions
    Vera Novak
    Division of Gerontology, Beth Israel Deaconess Medical Center, 110 Francis Street, Boston, MA 02215, USA
    Stroke 41:61-6. 2010
  6. pmc Nonlinear phase interaction between nonstationary signals: a comparison study of methods based on Hilbert-Huang and Fourier transforms
    Men Tzung Lo
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
    Phys Rev E Stat Nonlin Soft Matter Phys 79:061924. 2009
  7. pmc Vasoreactivity and peri-infarct hyperintensities in stroke
    P Zhao
    Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
    Neurology 72:643-9. 2009
  8. pmc Nonlinear pressure-flow relationship is able to detect asymmetry of brain blood circulation associated with midline shift
    Kun Hu
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
    J Neurotrauma 26:227-33. 2009
  9. pmc Modeling heart rate regulation--part I: sit-to-stand versus head-up tilt
    Mette S Olufsen
    Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC 27695, USA
    Cardiovasc Eng 8:73-87. 2008

Scientific Experts

Detail Information

Publications12

  1. pmc Impaired cerebral autoregulation is associated with brain atrophy and worse functional status in chronic ischemic stroke
    Mikio C Aoi
    Biomathematics Program, Department of Mathematics, North Carolina State University, Raleigh, NC, USA
    PLoS ONE 7:e46794. 2012
    ..002). Our results indicate that better dynamic cerebral perfusion regulation is associated with less atrophy and better long-term functional status in older adults with chronic ischemic infarctions...
  2. pmc Nonlinear assessment of cerebral autoregulation from spontaneous blood pressure and cerebral blood flow fluctuations
    Kun Hu
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, 812 Stoneman Bldg, 330 Brookline Avenue, Boston, MA 02115, USA
    Cardiovasc Eng 8:60-71. 2008
    ....
  3. pmc Hypertension and cerebral vasoreactivity: a continuous arterial spin labeling magnetic resonance imaging study
    Ihab Hajjar
    Harvard Medical School, Institute for Aging Research Hebrew SeniorLife, Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, MA 02131, USA
    Hypertension 56:859-64. 2010
    ..Because lower vasoreactivity is associated with poor outcomes, studies of the impact of antihypertensive on vasoreactivity are important...
  4. pmc Association of blood pressure elevation and nocturnal dipping with brain atrophy, perfusion and functional measures in stroke and nonstroke individuals
    Ihab Hajjar
    Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
    Am J Hypertens 23:17-23. 2010
    ..Although both blood pressure elevation and lower nocturnal dipping increase vascular risk, it is not known whether either or both are also associated with brain atrophy, cerebral perfusion, and functional status...
  5. pmc Cerebral flow velocities during daily activities depend on blood pressure in patients with chronic ischemic infarctions
    Vera Novak
    Division of Gerontology, Beth Israel Deaconess Medical Center, 110 Francis Street, Boston, MA 02215, USA
    Stroke 41:61-6. 2010
    ..Target blood pressure (BP) values for optimal cerebral perfusion after an ischemic stroke are still debated. We sought to examine the relationship between BP and cerebral blood flow velocities (BFVs) during daily activities...
  6. pmc Nonlinear phase interaction between nonstationary signals: a comparison study of methods based on Hilbert-Huang and Fourier transforms
    Men Tzung Lo
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
    Phys Rev E Stat Nonlin Soft Matter Phys 79:061924. 2009
    ..Furthermore, we propose certain strategies that can be implemented in the TFA and the MMPF methods to reduce the effects of nonstationarities, thus improving the performances of the two methods...
  7. pmc Vasoreactivity and peri-infarct hyperintensities in stroke
    P Zhao
    Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
    Neurology 72:643-9. 2009
    ..We investigated the regional differences in CO2 vasoreactivity (CO2 VR) and their relationships to peri-infarct T2 hyperintensities (PIHs), chronic infarct volumes, and clinical outcomes...
  8. pmc Nonlinear pressure-flow relationship is able to detect asymmetry of brain blood circulation associated with midline shift
    Kun Hu
    Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
    J Neurotrauma 26:227-33. 2009
    ..Moreover, mean pressure-flow phase shift is sensitive to the displacement of midline of the brain, and may potentially serve as a marker of asymmetry of cerebral autoregulation...
  9. pmc Modeling heart rate regulation--part I: sit-to-stand versus head-up tilt
    Mette S Olufsen
    Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC 27695, USA
    Cardiovasc Eng 8:73-87. 2008
    ....