CAR 5. Carotid Flow Volume Measurement in Doppler Ultrasound as a New Look at the Diagnosis of Internal Carotid Artery Stenosis

Abstract

Blood flow velocity criteria in the diagnosis of carotid stenosis are well defined; however, there are no reference values concerning blood flow volume. The objective of this work covered assessment of blood flow volume in the internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA) in healthy volunteers and asymptomatic patients with carotid artery disease older than 65 years with the aim of implementation of blood flow volume measurements in clinical assessment of patients with carotid artery disease. There were 303 patients without history of neurologic symptoms included in the examination. The group of 123 healthy volunteers older than 65 years, without comorbidities that may alter cerebral blood flow volume, were examined to determine reference flow volume values in the ICA, ECA, and VA. The flow parameters in this group were compared with the flow in 56 healthy volunteers younger than 65 years. To determine the influence of ICA stenosis on cerebral blood flow volume, the group of 124 patients older than 65 years with asymptomatic ICA stenosis without comorbidities that might influence hemodynamics of blood flow were examined. In all patients, an extensive Doppler ultrasound examination with measurement of blood flow volume in the ICA, ECA, and VA was performed. Cerebral blood flow volume reference values in patients older than 65 years were determined. Gradual decline in cerebral blood flow, caused mainly by the significant reduction of ICA flow volume, was observed in healthy volunteers. A decline in the peak systolic and end-diastolic velocities in the ICA and the peak systolic velocity in the ECA was observed. Two subgroups with ICA stenosis and flow volume changes were identified: patients with compensatory elevation of blood flow volume and those without compensation whose flow volume was lower than reference values. The latter subgroup contained mainly patients with >50% ICA stenosis. Among asymptomatic patients with significant ICA stenosis, there is a subgroup without compensatory elevation of blood flow volume. Those patients may be more vulnerable to cerebral ischemia and featured with increased risk of ischemic stroke.