Hanieh Mohammadi, is a Biomedical Engineering Ph.D. candidate at Ecole Polytechnique Montreal, Montreal, Canada. She received her master of Biomedical Engineering from University of Bern, Bern Switzerland in 2014. She was working as a research assistant at EPFL, Lausanne, Switzerland during years of 2012 to 2014. Currently, her work focused on the effect changes of brain pulsatility during lifespan in the healthy and with cardiovascular disease elderly individuals.
The effect of coronary artery disease on regional cortical pulsatility in elderly individuals
The World Health Organization estimates that 30% of deaths in high-income countries are due to chronic vascular diseases (CVD), also known to be associated with cerebrovascular damage. Moreover, the elder population is the most impacted since adults older than 65 years accounted for 82% of all deaths attributable to CVD in the U.S. It is thought that vascular impairments result in a variety of downstream lesions in the brain. This damage can, in turn, lead to cognitive decline and hence decreased the quality of life that can be endured for decades given the chronic nature of these diseases. This age-related cognitive decline linked to CVD could mainly be caused by stiffening of the arterial tree which in turn damages the cerebral micro-circulation causing blood flow abnormalities and hence neural function impairment.
Cerebral pulsatility, computed from differences between systolic and diastolic flow velocities, is assumed to reflect cerebrovascular resistance. To shed the light on the link between local cortical pulsatility changes as a result of CVD, cerebral pulse was measured using time domain Near Infrared Spectroscopy (NIRS) . NIRS measures relative absorption changes of oxy- and deoxy-hemoglobin while fluctuations in the signal occur not only with variations in tissue oxygenation but also with arterial pulsatility.
The data-driven results demonstrated that the extracted cerebral pulse parameters using NIRS could quantify changes in local cerebrovascular tone. In comparison to patients with CVD, the healthy group had smaller peak pulse amplitudes, higher arterial compliance and slower pulse velocity in the brain. In addition, patients with CVD tended to show a significant decline in cerebrovascular reactivity. Taken together, this study suggests that cerebral pulsatility measures (pulsatility index, compliance) discriminate CVD patients and healthy control while also showing an inverse correlation with age.