Effect of CGRP inhibitors on interictal cerebral hemodynamics in individuals with migraine.

Introduction: Calcitonin gene-related peptide (CGRP) plays an important role in cerebral vasodilation, so here we aim to quantify the impact of CGRP monoclonal antibody (mAb) therapy on cerebral hemodynamics. Methods: In 23 patients with chronic and episodic migraine, cerebral hemodynamic monitoring was performed (1) prior to and (2) 3-months into CGRP-mAb therapy. Transcranial Doppler monitored cerebral blood flow velocity (CBFv) in the middle cerebral artery (MCA) and posterior cerebral artery (PCA), from which cerebrovascular reactivity (CVR) and cerebral autoregulation (CA; Mx-index) were calculated. Results: CA was similar off and on treatment, in the MCA (p = 0.42) and PCA (p = 0.72). CVR was also unaffected by treatment, in the MCA (p = 0.38) and PCA (p = 0.92). CBFv and blood pressure were also unaffected. The subgroup of clinical responders (>50% reduction in migraine frequency) exhibited a small reduction in MCA-CBFv (6.0 cm/s; IQR: 1.1-12.4; p = 0.007) and PCA-CBFv (8.9 cm/s; IQR: 6.9-10.3; p = 0.04). Discussion: Dynamic measures of cerebrovascular physiology were preserved after 3 months of CGRP-mAb therapy, but a small reduction in CBFv was observed in patients who responded to treatment. Subgroup findings should be interpreted cautiously, but further investigation may clarify if CBFv is dependent on the degree of CGRP inhibition or may serve as a biomarker of drug sensitivity.

Noninvasive finger plethysmography for continuous blood pressure monitoring in patients with left ventricular assist device.

BACKGROUND: Accurate blood pressure (BP) measurement remains challenging in patients with HeartMate 3™ left ventricular assist devices (HM3 LVADs). The Finapres® NOVA is a promising non-invasive continuous BP monitor that uses the volume clamp method via a finger cuff, so here we aimed to validate the instrument in HM3 patients. METHODS: In a single-center cohort, BP was monitored in 15 patients within 72 h following HM3 implantation. A radial artery catheter quantified arterial blood pressure (ABP), while the NOVA measured finger arterial pressure (fiAP) and reconstructed brachial artery pressure (reBAP). Waveforms were recorded for 10 min, and mean values were calculated in 15-s intervals. RESUTS: fiAP and ABP were moderately correlated during both the first (ICC 0.61, p = 0.04) and final measurements (ICC 0.66, p = 0.03). reBAP and ABP were strongly correlated during both the first (ICC 0.81, p = 0.002) and final measurements (ICC 0.83, p = 0.001). Both NOVA-derived values may underestimate low BP values while overestimating relatively high BP values. The reBAP was within 5 mm Hg of the ABP in 40% of patients (and within 10 mm Hg in 67%). CONCLUSIONS: This pilot represents the first evidence in support of the Finapres® NOVA for non-invasive BP measurement in select patients with HM3 LVADs. The instrument may provide useful data during BP medication adjustments or pump titration, but despite the correlation between the non-invasive reBAP and invasive ABP, individual-level inaccuracy may be clinically meaningful. Further investigation is needed to clarify these limitations and optimize accuracy before widespread adoption in this unique patient population.

Differentiating Dynamic Cerebral Autoregulation Across Vascular Territories.

Objective: Transcranial Doppler is commonly used to calculate cerebral autoregulation, but measurements are typically restricted to a single cerebral artery. In exploring topographic heterogeneity, this study reports the first thorough comparison of autoregulation in all major cerebral vessels. Methods: In forty healthy adults, flow velocity was monitored in the anterior, middle, and posterior cerebral arteries, and synchronized with arterial blood pressure. A transfer function analysis provided characteristics of autoregulation by quantifying the relationship between blood pressure and cerebral blood flow velocity. Results: Phase, which quantifies the time course of autoregulation, was similar in all vessels. Gain, which quantifies the magnitude of hemodynamic regulation, was lower in posterior cerebral artery, indicative of tighter regulation. However, after adjusting for baseline flow differences in each vascular territory, normalized gain was similar in all vessels. Conclusions: Discriminating dynamic cerebral autoregulation between cerebrovascular territories is feasible with a transcranial doppler based approach. In the posterior cerebral artery of healthy volunteers, absolute flow is more tightly regulated, but relative flow regulation is consistent across cerebrovascular territories. Significance: The methodology can be applied to focal disease states such as stroke or posterior reversible encephalopathy syndrome, in which the topographic distribution of autoregulation may be particularly critical.