BRAIN-HEART Ultrasound Study Normative Values for Transcranial Doppler Based Cerebral Blood Flow Assessment

Overview

There is a dire need to establish normative values for transcranial Doppler(TCD) derived cerebral blood flow parameters for each type of Mechanical circulatory support (MCS) device and explore the relationship between the MCS device's systemic flow dynamics and TCD based cerebral flow(CBF) parameters TCD derived cerebral blood flow parameters can then be investigated as targets used to titrate systemic flow dynamics from MCS. Having target flow rates titrated to patient specific condition using TCD may help avoid both hypoperfusion as well as the possibility of hyperemia reperfusion injury contributing to neurological morbidity. We propose a multicenter study to gather normative data on TCD derived CBF and MCS systemic dynamics for a wide range of patient demographics. Such data collection is only possible with multi-center collaboration given the small volume of patients with MCS patients in each center.

The Mechanical circulatory support (MCS) devices are temporary devices that enable complete and immediate cardiopulmonary support in settings of cardiac arrest and cardiogenic shock. The different MCS devices differ in their operating principles and generate different systemic flow patterns (pulsatile vs non- pulsatile, flow volumes, Peak flow rates, and PI). Researchers have studied different MCS devices like VA Extra Corporeal Mebrane Oxygenation(ECMO), left ventricular assist device (LVAD), and Impella and their effect on cerebral flow and complication profiles using various neuromonitoring techniques including TCD . Most such studies were small single-center studies that added to the understanding of different flow rates and characteristics with different MCS devices but were not adequately powered or designed to establish normative values of TCD derived CBF measures in this special population. There is a dire need to establish normative values for each type of MCS device and explore the relationship between the MCS device's systemic flow dynamics and TCD derived cerebral flow. These normative values then can be used to assess the association of TCD derived CBF patterns with occurrence of neurological complications related to abnormal CBF in patients receiving MCS devices and advice on patient specific MCS parameters titrated using TCD derived parameters. Having target flow rates in MCS patients will help avoid both hypoperfusion as well as the possibility of hyperemia reperfusion injury contributing to neurological morbidity. Such data collection is only possible with multi-center collaboration given the small volume of patients with MCS patients in each center.