Cerebral Blood Flow Autoregulation Is Preserved After Continuous-Flow Left Ventricular Assist Device Implantation

Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD.
Journal of cardiothoracic and vascular anesthesia (Impact Factor: 1.46). 12/2012; 26(6):1022-8. DOI: 10.1053/j.jvca.2012.07.014
Source: PubMed


To compare cerebral blood flow (CBF) autoregulation in patients undergoing continuous-flow left ventricular assist device (LVAD) implantation with that in patients undergoing coronary artery bypass grafting (CABG).
Prospective, observational, controlled study.
Academic medical center.
Fifteen patients undergoing LVAD insertion and 10 patients undergoing CABG.
Cerebral autoregulation was monitored with transcranial Doppler and near-infrared spectroscopy. A continuous Pearson correlation coefficient was calculated between mean arterial pressure (MAP) and CBF velocity and between MAP and near-infrared spectroscopic data, rendering the variables mean velocity index (Mx) and cerebral oximetry index (COx), respectively. Mx and COx approach 0 when autoregulation is intact (no correlation between CBF and MAP), but approach 1 when autoregulation is impaired. Mx was lower during and immediately after cardiopulmonary bypass in the LVAD group than in the CABG group, indicating better-preserved autoregulation. Based on COx monitoring, autoregulation tended to be better preserved in the LVAD group than in the CABG group immediately after surgery (p = 0.0906). On postoperative day 1, COx was lower in the LVAD group than in the CABG group, indicating preserved CBF autoregulation (p = 0.0410). Based on COx monitoring, 3 patients (30%) in the CABG group had abnormal autoregulation (COx ≥0.3) on the first postoperative day but no patient in the LVAD group had this abnormality (p = 0.037).
These data suggest that CBF autoregulation is preserved during and immediately after surgery in patients undergoing LVAD insertion.

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    ABSTRACT: Neurologic injury remains a common complication in patients undergoing mechanical support for cardiac and respiratory failure with either left ventricular assist devices (LVAD) or extracorporeal membrane oxygenation (ECMO). Cerebral near-infrared spectroscopy (NIRS) has been recognized clinically as a valid, continuous, and practical monitor of cerebral perfusion in cardiac surgery. Recently, interest in utilizing this technology to monitor patients while undergoing LVAD and ECMO placement and their resultant care has expanded. The purpose of this review is to discuss the practical approaches to using cerebral NIRS for LVAD and ECMO implantation. Recent studies suggest that implementation of cerebral NIRS monitoring during LVAD and ECMO implantation may reduce the perioperative neurological complications. In addition, cerebral NIRS can function as a first-alert monitor to warn of problems with oxygenation, ventilation, mixed venous oxygen saturation, and cardiac output. Despite an overall small body of literature, early evidence suggests a possible beneficial effect of utilizing cerebral NIRS during LVAD and ECMO implantation. Prospective randomized studies are needed to develop algorithm-based therapies centered on NIRS monitoring. On the basis of potential benefits and minimal risks in relation to cerebral NIRS, it is recommended that it be utilized during the operative and immediate postoperative period in the LVAD and ECMO patient population. VIDEO ABSTRACT:
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    ABSTRACT: Background Insertion of a left ventricular assist device (LVAD) is an accepted therapy for advanced heart failure patients. However, The effects on end-organ perfusion, including cerebral autoregulation, are unclear in The presence of reduced pulsatility. Therefore, The objective of this study was to determine whether cerebral autoregulation is impaired in patients with continuous-flow (CF) LVADs. Methods Dynamic cerebral autoregulation was assessed in both time-domain (autoregulatory index) and frequency-domain (transfer function analysis) analyses in 9 CF-LVAD subjects, 5 pulsatile LVAD subjects and 10 healthy controls, by evaluating mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) during a sit-stand maneuver at 0.05 Hz (10-second sit, 10-second stand). The autoregulatory index was calculated as The percent change in mean CBFV per mm Hg change in MAP. Results The magnitude of oscillation in MAP and CBFV was greater in subjects with pulsatile LVADs than either CF-LVADs or healthy controls (p = 0.065 for MAP, p = 0.004 for CBFV). The autoregulatory index and transfer function gain were similar among groups, indicating that dynamic cerebral autoregulation is preserved among patients with CF-LVADs. Conclusions Cerebral blood flow in patients with CF-LVADs is comparable to that of healthy controls across a range of blood pressures. Patients with pulsatile devices have greater oscillations in MAP and CBFV. However, dynamic cerebral autoregulation is preserved among subjects with either type of device. Thus, The reduction in pulsatility afforded by CF-LVADs does not impair normal autoregulatory processes. © 2014 International Society for Heart and Lung Transplantation.
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