Significance: The critical closing pressure (CrCP) of cerebral circulation, as measured by diffuse correlation spectroscopy (DCS), is a promising biomarker of intracranial hypertension. However, CrCP techniques using DCS have not been assessed in gold standard experiments.

Aim: CrCP is typically calculated by examining the variation of cerebral blood flow (CBF) during the cardiac cycle (with normal sinus rhythm). We compare this typical CrCP measurement with a gold standard obtained during the drops in arterial blood pressure (ABP) caused by rapid ventricular pacing (RVP) in patients undergoing invasive electrophysiologic procedures.

Approach: Adults receiving electrophysiology procedures with planned ablation were enrolled for DCS CBF monitoring. CrCP was calculated from CBF and ABP data by three methods: (1) linear extrapolation of data during RVP (CrCP_RVP; the gold standard); (2) linear extrapolation of data during regular heartbeats (CrCP_Linear); and (3) fundamental harmonic Fourier filtering of data during regular heartbeats (CrCP_Fourier).

Results: CBF monitoring was performed prior to and during 55 episodes of RVP in five adults. CrCP_RVP and CrCP_Fourier demonstrated agreement (R = 0.66, slope = 1.05 (95%CI, 0.72 to 1.38). Agreement between CrCP_RVP and CrCP_Linear was worse; CrCP_Linear was 8.2 ± 5.9 mmHg higher than CrCP_RVP (mean ± SD; p < 0.001).

Conclusions: Our results suggest that DCS-measured CrCP can be accurately acquired during normal sinus rhythm.