A Comparison Between Pressure Wire and Microcatheter Measurements for Evaluating the Cerebral Venous Pressure Gradient

Correlation between intravascular pressure gradients and ultrasound velocities in carotid artery stenosis: An exploratory study

INTRODUCTION

Grading of carotid stenosis is routinely performed with non-invasive techniques, such as carotid ultrasound (CUS) and computerized tomography angiography (CTA), which have limitations in grading definition. Moreover, the actual hemodynamic impact of a stenosis remains poorly defined. Preliminary studies explored the application of the resting full-cycle ratio (RFR), measured with pressure wire (PW), but the correlation between RFR and morphological/hemodynamic parameters is still undefined. This study aims to test the correlation between RFR and CUS-CTA-DSA based degree of stenosis, to define the suitability of RFR as carotid stenosis index.

METHODS

We included patients with symptomatic carotid stenosis receiving carotid artery stenting (CAS), between November 2022 and May 2023. We performed CUS and PW measurements before and after stenting, at four different sites (trans-lesion, distal cervical, petrous and supraclinoid internal carotid artery [ICA] segments). We compared CUS and PW parameters by Pearson's or Spearman test for continuous variables.

RESULTS

Among 15 patients included the mean stenosis degree was 81.3%. Trans-lesion RFR was significantly higher than other sites (0.72 ± 0.2 trans-lesion vs. 0.69 ± 0.18 distal cervical ICA vs. 0.66 ± 0.2 petrous ICA vs. 0.6 ± 0.2 intracranial ICA, p < 0.05). All RFR values significantly increased after treatment; the highest relative increase was registered at stenosis site (0.72 ± 0.2 pre-stent vs. 1.01 ± 0.1 post-stent, p < 0.01). Trans-lesion RFR was significantly associated with the CTA and DSA stenosis degree and CUS measurements.

CONCLUSIONS

Pressure wire in carotid artery stenosis seems safe and suitable. Resting full-cycle ratio has a significant correlation with CUS values and stenosis degree and might be used as carotid stenosis index during CAS.

Emergent cerebral venous stenting: A valid treatment option for fulminant idiopathic intracranial hypertension

BACKGROUND

Fulminant idiopathic intracranial hypertension (FIIH) is characterized by rapid, severe, progressive vision loss and often treated surgically. Cerebral transverse venous stenting (CTVS) is efficacious in IIH patients, but emergent CTVS in FIIH is rarely reported. We present our experience with emergent CTVS in patients with FIIH.

METHODS

Since 01/2019, an institutional protocol allowed emergent CTVS in FIIH patients with bilateral transverse sinus stenosis and gradient pressure > 15 on digital subtraction angiography (DSA). We retrospectively analyzed a prospective registry of all IIH patients with details of neurological and neuro-ophthalmological assessments before and after treatment, and subjective assessments of headache and tinnitus were made pre-and post-procedure.

RESULTS

259 IIH patients, including 49 who underwent CTVS, were registered. Among them, five female patients met inclusion criteria for FIIH and underwent emergent CTVS. FIIH patients were younger (18.8 ± 1.64 vs 27.7 ± 4.85, p < 0.01), mean BMI was lower (30.8 ± 10.57 vs 34.6 ± 4.3, p < 0.01), and lumbar puncture opening pressure higher (454 ± vs 361 ± 99.4, p < 0.01) than that of IIH patients. They presented with acute visual loss, severe headache, papilledema, significant bilateral transverse sinus stenosis on CT-venography, and mean dominant side gradient pressure of 26.4 ± 6.2 on DSA. CTVS was performed without significant complications, resulting in remarkable improvement in headache, optical coherence tomography, and visual fields within 1 week. At 1-year follow-up (four patients) and 6-month follow-up (1 patient), there was complete resolution of papilledema and headache, and marked improvement in visual acuity.

CONCLUSIONS

In these patients, emergent-CTVS was a safe and effective treatment option for FIIH. Further evaluation is warranted.

Estimation of venous sinus pressure drop in patients with idiopathic intracranial hypertension using 4D-flow MRI

OBJECTIVE

We aimed to explore a non-invasive estimate of pressure drop in patients who undergo venous sinus stenting to treat idiopathic intracranial hypertension (IIH).

METHODS

This prospective study included 28 IIH patients scheduled for venous stenting. 4D-flow MRI was acquired 24-48 h before venous manometry. Manometry-obtained pressure drop (Mp) was dichotomized into low (Lp: 0-8 mmHg) and high (Hp: 8-30 mmHg) groups. Hemodynamic indices were compared between Lp and Hp. Trans-stenotic pressure drop was estimated by work-energy equation, simplified Bernoulli equation, vorticity magnitude, and velocity difference between inlet and outlet and was compared with Mp. Measurement agreement, correlation, and accuracy were evaluated using the κ coefficient, Pearson's r, and confusion matrix-derived accuracy.

RESULTS

Among 28 patients (mean age 38.8 ± 12.7), 19 (67.9%) were female. Work-energy equation-estimated pressure drop (WEp) had strong correlation (r = 0.91, 95% confidence interval [CI]: 0.81-0.96, p < 0.001) and high agreement (intraclass correlation coefficient = 0.90, 95% CI: 0.78-0.95, p < 0.001) with Mp. WEp classified Lp and Hp with an accuracy of 0.96. The κ value between WEp and Mp was 0.92 (95% CI: 0.78-1.00). In the work-energy equation, the viscosity energy term (V_e) had the largest weights, and the ratio of V_e to the summation of the three energy terms was 0.93 ± 0.07. V_e had strong correlation with mVort (r = 0.93, 95% CI: 0.85-0.97, p < 0.001), and mean vorticity magnitude was significantly elevated in Hp compared to that in Lp (259.8 vs. 174.9 mL/s, p < 0.001).

CONCLUSION

Trans-stenotic pressure drop in IIH can be estimated using the work-energy equation with favorable accuracy.

KEY POINTS

• Trans-stenotic pressure drop in patients with idiopathic intracranial hypertension can be estimated accurately with the work-energy equation using the 4D-flow MRI full velocity field. • Compared with traditional venous sinus manometry, the 4D-flow MRI-derived pressure drop is totally non-invasive and cost-saving. • 4D-flow MRI may help neurointerventionalist to select IIH patients suitable for venous sinus stenting.