Differences in Pressure Within the Sac of Human Ruptured and Nonruptured Cerebral Aneurysms

Low Wall Shear Stress and High Intra-aneurysmal Pressure are Associated with Ruptured Status of Vertebral Artery Dissecting Aneurysms

PURPOSE

The morphological and hemodynamic features of patients with vertebral artery dissecting aneurysms (VADAs) are yet unknown. This study sought to elucidate morphological and hemodynamic features of patients with ruptured and unruptured VADAs based on computed flow simulation.

METHODS

Fifty-two patients (31 unruptured and 21 ruptured VADAs) were admitted to two hospitals between March 2016 and October 2021. All VADAs were located in the intradural segment, and their clinical, morphological, and hemodynamic parameters were retrospectively analyzed. The hemodynamic parameters were determined through computational fluid dynamics simulations. Univariate statistical and multivariable logistic regression analyses were employed to select significantly different parameters and identify key factors. Receiver operating characteristic (ROC) analysis was used to assess the discrimination for each key factor.

RESULTS

Four hemodynamic parameters were observed to significantly differ between ruptured and unruptured VADAs, including wall shear stress (WSS), low shear area, intra-aneurysmal pressure (IAP), and relative residence time. However, no significant differences were observed in morphological parameters between ruptured and unruptured VADAs. Multivariable logistic regression analysis revealed that low WSS and high IAP were significantly observed in the ruptured VADAs and demonstrated adequate discrimination.

CONCLUSIONS

This research indicates significant hemodynamic differences, but no morphological differences were observed between ruptured and unruptured VADAs. The ruptured group had significantly lower WSS and higher IAP than the unruptured group. To further confirm the roles of low WSS and high IAP in the rupture of VADAs, large prospective studies and long-term follow-up of unruptured VADAs are required.

Could outcomes of intracranial aneurysms be better predict using serum creatinine and glomerular filtration rate?

Purpose:

To analyze the role of serum creatinine levels as a biomarker of intracranial aneurysm outcomes.

Methods:

This is a prospective analysis of outcomes of patients with intracranial aneurysm. One hundred forty-seven patients with serum creatinine at admission and 6 months follow up were included. Linear and logistic regressions were used to analyze the data. Modified Rankin scale (mRS) was used to assess outcome.

Results:

Creatinine level was not directly related to aneurysm outcome nor aneurysm rupture (p > 0.05). However, patients with a glomerular filtration rate (GFR) lower than 72.50 mL·min^–1 had an odds ratio (OR) of 3.049 (p = 0.006) for worse outcome. Similarly, aneurysm rupture had an OR of 2.957 (p = 0.014) for worse outcomes. Stepwise selection model selected 4 variables for outcomes prediction: serum creatinine, sex, hypertension and treatment. Hypertensive patients had, on average, an increase in 0.588 in mRS (p = 0.022), while treatment with microsurgery had a decrease in 0.555 (p = 0.038).

Conclusions:

Patients with higher GFR had better outcomes after 6 months. Patients with higher GFR had better outcomes after 6 months. Creatinine presented an indirect role in GFR values and should be included in models for outcome prediction.

Endovascular catheter manometry reliability: a benchtop validation study

OBJECTIVE

Catheter manometry is used frequently in neuroendovascular surgery for assessing cerebrovascular pathology. The accuracy of pressure data with different catheter setups requires further validation.

METHODS

In a silicone human vascular model with a pulsatile pump, pressure measurements were taken through multiple arrangements of 2 guide catheters and 6 microcatheters. The systolic pressure, diastolic pressure, mean pressure, pulse pressure, and area under the curve of the waveform were recorded through catheters with controls at arterial blood pressure ranges. Linear regression modeling was performed, correlating transduction area and relative pulse pressure. Thresholds for acceptable accuracy were ≥ 90%.

RESULTS

Mean pressure demonstrated < 4% variation between all 24 catheter setups and respective controls. A strong linear correlation (r2 = 0.843, p < 0.0005) between microcatheter transduction area and relative pulse pressure with a threshold of 0.50 mm2 was seen (i.e., 0.031-inch inner diameter [ID]). For guide catheters with indwelling microcatheters, there was also a strong linear correlation (r2 = 0.840, p < 0.0005) of transduction area to pulse pressure. The guide catheters with obstructing microcatheters required a transduction area over fourfold higher compared with unobstructed microcatheters (2.21 mm2 vs 0.50 mm2).

CONCLUSIONS

Mean pressure measurements are accurate through microcatheters as small as 0.013-inch ID. Pulse pressure and waveform morphology may require a microcatheter ≥ 0.031-inch ID to achieve 90% accuracy, although the 0.027-inch ID microcatheter reached 85% accuracy. A 0.070-inch guide catheter with a microcatheter ≤ 0.042-inch outer diameter (e.g., Marksman 0.027-inch ID or smaller) allows accurate transduction of pulse pressure. Further validation of these benchtop findings is necessary before application in a clinical setting.

Intra-aneurysmal pressure changes during stent-assisted coiling

We aimed to examine aneurysm hemodynamics with intra-saccular pressure measurement, and compare the effects of coiling, stenting and stent-assisted coiling in proximal segments of intracranial circulation. A cohort of 45 patients underwent elective endovascular coil embolization (with or without stent) for intracranial aneurysm at our department. Arterial pressure transducer was used for all measurements. It was attached to proximal end of the microcatheter. Measurements were taken in the parent artery before and after embolization, at the aneurysm dome before embolization, after stent implantation, and after embolization. Stent-assisted coiling was performed with 4 different stents: LVIS and LVIS Jr (Microvention, Tustin, CA, USA), Leo (Balt, Montmorency, France), Barrel VRD (Medtronic/ Covidien, Irvine, CA, USA). Presence of the stent showed significant reverse correlation with intra-aneurysmal pressure–both systolic and diastolic—after its implantation (r = -0.70 and r = -0.75, respectively), which was further supported by correlations with stent cell size–r = 0.72 and r = 0.71, respectively (P<0.05). Stent implantation resulted in significant decrease in diastolic intra-aneurysmal pressure (p = 0.046). Systolic or mean intra-aneurysmal pressure did not differ significantly. Embolization did not significantly change the intra-aneurysmal pressure in matched pairs, regardless of the use of stent (p>0.05). In conclusion, low-profile braided stents show a potential to divert blood flow, there was significant decrease in diastolic pressure after stent placement. Flow-diverting properties were related to stent porosity. Coiling does not significantly change the intra-aneurysmal pressure, regardless of packing density.