The Cut Flow Index: An Intraoperative Predictor of the Success of Extracranial-Intracranial Bypass for Occlusive Cerebrovascular Disease

Abstract OBJECTIVE: There has been a resurgence of interest in selective extracranial-intracranial bypass for revascularization of cerebrovascular occlusive disease. We evaluated the usefulness of intraoperative blood flow measurements in predicting graft success after extracranial-intracranial bypass. METHODS: A retrospective review of 51 cases of extracranial-intracranial bypass for purposes of flow augmentation in the setting of cerebrovascular occlusive disease was performed. In all cases, free flow from the cut end of the donor vessel, termed cut flow, was measured. The cut flow index (CFI) (bypass flow [ml/min] / cut flow [ml/min]) was derived and correlated with bypass patency, postoperative bypass flow, cerebrovascular reserve testing, and clinical outcome. RESULTS: The CFI was a significant predictor of bypass patency (P = 0.002). Using a CFI of 0.5 as a threshold, the bypass patency rate was 92% in cases with a CFI greater than 0.5 compared with 50% in cases with a CFI less than 0.5. Intraoperative bypass flow correlated well with postoperative measurements obtained from quantitative phase-contrast magnetic resonance imaging. An analysis of cases with a poor CFI indicated that a logical interpretation of bypass function can be performed during surgery. CONCLUSION: A poor CFI can alert surgeons to potential difficulties with the donor vessel, anastomosis, or recipient vessel during surgery. Furthermore, a CFI closely approximating 1.0 provides physiological confirmation of impaired cerebrovascular reserve in the recipient bed.

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The cut flow index revisited: utility of intraoperative blood flow measurements in extracranial-intracranial bypass surgery for ischemic cerebrovascular disease

Journal of Neurosurgery ◽

10.3171/2019.5.jns19641 ◽

2020 ◽

Vol 133 (5) ◽

pp. 1396-1400 ◽

Cited By ~ 3

Author(s):

Christopher J. Stapleton ◽

Gursant S. Atwal ◽

Ahmed E. Hussein ◽

Sepideh Amin-Hanjani ◽

Fady T. Charbel

Keyword(s):

Blood Flow ◽

Cerebrovascular Disease ◽

Bypass Surgery ◽

Flow Index ◽

Flow Measurements ◽

Ischemic Cerebrovascular Disease ◽

Bypass Patency ◽

Blood Flow Measurements

OBJECTIVEIn extracranial-intracranial (EC-IC) bypass surgery, the cut flow index (CFI) is the ratio of bypass flow (ml/min) to donor vessel cut flow (ml/min), and a CFI ≥ 0.5 has been shown to correlate with bypass patency. The authors sought to validate this observation in a large cohort of EC-IC bypasses for ischemic cerebrovascular disease with long-term angiographic follow-up.METHODSAll intracranial bypass procedures performed at a single institution between 2003 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and analyzed according to bypass patency with univariate and multivariate statistical analyses.RESULTSA total of 278 consecutive intracranial bypasses were performed during the study period, of which 157 (56.5%) were EC-IC bypasses for ischemic cerebrovascular disease. Intraoperative blood flow measurements were available in 146 patients, and angiographic follow-up was available at a mean of 2.1 ± 2.6 years after bypass. The mean CFI was significantly higher in patients with patent bypasses (0.92 vs 0.64, p = 0.003). The bypass patency rate was 83.1% in cases with a CFI ≥ 0.5 compared with 46.4% in cases with a CFI < 0.5 (p < 0.0001). Adjusting for age, sex, diagnosis, and single versus double anastomosis, the CFI remained a significant predictor of bypass patency (p = 0.001; OR 5.8, 95% CI 2.0–19.0). A low CFI was also associated with early versus late bypass nonpatency (p = 0.008).CONCLUSIONSA favorable CFI portends long-term EC-IC bypass patency, while a poor CFI predicts eventual bypass nonpatency and can alert surgeons to potential problems with the donor vessel, anastomosis, or recipient bed during surgery.

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Monoexponential Analysis of 133Xe Clearance Curves for Regional Cerebral Blood Flow Measurements

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1984.34 ◽

1984 ◽

Vol 4 (2) ◽

pp. 250-258 ◽

Cited By ~ 13

Author(s):

Erik Ryding

Keyword(s):

Weight Ratio ◽

Input Function ◽

Low Flow ◽

Flow Index ◽

Flow Measurements ◽

Clearance Curve ◽

Flow Components ◽

The One ◽

Blood Flow Measurements ◽

Fast Flow

The theoretical properties of a monoexponential flow index, analogous to the one used earlier by other investigators for regional CBF (rCBF) measured after intraarterial injection, were investigated after the administration of 133Xe intraarterially, intravenously, and by inhalation under high and low flow conditions. The sensitivity of the flow index to changes in fast flow components or changes in the weight ratio between the fast and the slow flow compartments was found to be dependent on whichever part of the 133Xe clearance curve was used for the flow calculation and on the shape of the input function for 133Xe. Since biexponential analysis of the clearance curves includes a monoexponential approximation for each of the two components of the clearance curve corresponding to the high and the low flow “families” in the brain, the limitations of the monoexponential flow index observed are in principle also valid for the results of biexponential analysis of the clearance curves.

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Quantitative angiographic haemodynamic evaluation of bypasses for complex aneurysms: a preliminary study

Stroke and Vascular Neurology ◽

10.1136/svn-2021-000858 ◽

2021 ◽

pp. svn-2021-000858

Author(s):

Junlin Lu ◽

Chao Xue ◽

Xulin Hu ◽

Yuanli Zhao ◽

Dong Zhang ◽

...

Keyword(s):

Blood Volume ◽

Cerebral Blood Volume ◽

Preoperative Evaluation ◽

Neurological Deficits ◽

Flow Index ◽

Flow Measurements ◽

Complex Aneurysms ◽

Preliminary Study ◽

Blood Flow Measurements ◽

Arterial Anatomy

ObjectiveOpen microsurgery, often with bypass techniques, is indispensable for complex aneurysms. To date, it remains unknown whether arterial anatomy or quantitative blood flow measurements can predict insufficient flow-related stroke (IRS). The present study aimed to evaluate the risk factors for IRS in patients treated with open microsurgery with bypass procedures for complex internal carotid artery aneurysms.MethodsPatients with complex aneurysms undergoing bypass surgery were retrospectively reviewed. The recipient/donor flow index (RDFI) was preoperatively evaluated using colour-coding angiography. RDFI was defined as the ratio of the cerebral blood volume of the recipient and donor arteries. The sizes of the recipient and donor arteries were measured. The recipient/donor diameter index (RDDI) was then calculated. IRS was defined as the presence of new postoperative neurological deficits and infarction on postoperative CT scans. We assessed the association between RDFI and other variables and the IRS.ResultsTwenty patients (38±12 years) were analysed. IRS was observed in 12 patients (60%). Patients with postoperative IRS had a higher RDFI than those without postoperative IRS (p<0.001). RDDI was not significantly different between patients with and without IRS (p=0.905). Patients with RDFI >2.3 were more likely to develop IRS (p<0.001).ConclusionQuantitative digital subtraction angiography enables preoperative evaluation of cerebral blood volume. RDFI >2.3, rather than RDDI, was significantly associated with postoperative IRS. This preoperative evaluation allows appropriate decisions regarding the treatment strategy for preventing postoperative IRS.

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One-donor, two-recipient extracranial-intracranial bypass series for moyamoya and cerebral occlusive disease: rationale, clinical and angiographic outcomes, and intraoperative blood flow analysis

Journal of Neurosurgery ◽

10.3171/2021.2.jns204333 ◽

2021 ◽

pp. 1-10

Author(s):

Nickalus R. Khan ◽

Victor M. Lu ◽

Turki Elarjani ◽

Michael A. Silva ◽

Aria M. Jamshidi ◽

...

Keyword(s):

Blood Flow ◽

Flow Analysis ◽

Measurement Data ◽

Senior Author ◽

Flow Index ◽

Flow Measurements ◽

Bypass Patency ◽

Significant Difference ◽

The Mean

OBJECTIVE Cerebral extracranial-intracranial (EC-IC) direct bypass is a commonly used procedure for ischemic vasculopathy. A previously described variation of this technique is to utilize one donor artery to supply two recipient arteries, which the authors designate as 1D2R. The purpose of this study is to present a single surgeon’s series of 1D2R direct bypasses for moyamoya and ischemia using detailed clinical, angiographic, and intraoperative blood flow measurement data. To the authors’ knowledge, this is the largest series reported to date. METHODS Hospital, office, and radiographic imaging records for all patients who underwent cerebral revascularization using a 1D2R bypass by the senior author were reviewed. The patients’ demographic information, clinical presentation, associated medical conditions, intraoperative information, and postoperative course were obtained from reviewing the medical records. RESULTS A total of 21 1D2R bypasses were performed in 19 patients during the study period. Immediate bypass patency was 100% and was 90% on delayed follow-up. The mean initial cut flow index (CFI(i)) was 0.64 ± 0.33 prior to the second anastomosis and the mean final value (CFI(f)) was 0.94 ± 0.38 after the second anastomosis (p < 0.001). The overall bypass flow increased on average by 50% (mean 17.9 ml/min, range −10 to 40 ml/min) with the addition of the second anastomosis. There was no significant difference in the overall flow measurements when the end-to-side anastomosis or side-to-side anastomosis was performed first. There was a statistically significant difference in the proportion of patients with a modified Rankin Scale (mRS) score of 0 or 1 postoperatively compared to preoperatively (p < 0.01). Through the application of Poiseuille’s law, the authors analyzed flow dynamics, deduced the component vascular resistances based on an analogy to electrical circuits and Ohm’s law, and introduced the new concepts of “second anastomosis relative augmentation” and “second anastomosis sink index” in the evaluation of 1D2R bypasses. CONCLUSIONS The application of the 1D2R technique in a series of 19 consecutive patients undergoing direct EC-IC bypass for flow augmentation demonstrated high patency rates, statistically significantly higher CFIs compared to 1D1R, and improved mRS scores at last clinical follow-up. Additionally, the technique allows a shorter dissection time and preserves blood flow to the scalp. The routine utilization of intraoperative volumetric flow measurements in such surgeries allows a deeper understanding of the hemodynamic impact on individual patients.

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Predictors of patency of excimer laser–assisted nonocclusive extracranial-to-intracranial bypasses

Journal of Neurosurgery ◽

10.3171/2008.9.jns08646 ◽

2009 ◽

Vol 110 (5) ◽

pp. 887-895 ◽

Cited By ~ 12

Author(s):

Jochem P. Bremmer ◽

Bon H. Verweij ◽

Catharina J. M. Klijn ◽

Albert van der Zwan ◽

L. Jaap Kappelle ◽

...

Keyword(s):

Excimer Laser ◽

Important Determinant ◽

Patient Characteristics ◽

Bypass Flow ◽

Flow Measurements ◽

Bypass Patency ◽

Temporary Occlusion ◽

Male Sex ◽

Surgical Aspects ◽

Prospective Database

Object Excimer laser–assisted nonocclusive anastomosis (ELANA) is a technique that can be used for extracranial-to-intracranial (EC-IC) bypasses, without the necessity of temporary occlusion of the donor or recipient artery. Information on predictors of patency of EC-IC bypasses in general and the ELANA bypass in particular is sparse. The authors studied 159 ELANA EC-IC bypasses to find predictors of patency. Methods From a prospective database of patients who underwent EC-IC bypass surgery, 143 consecutive patients who underwent a total of 159 ELANA bypasses were studied. The associations of patient characteristics, surgical aspects, and technical aspects specific to the ELANA technique with intraoperative and postoperative bypass patency were studied using logistic regression analysis. Results At the end of the operation, 146 (92%) of the 159 bypasses were patent. A first attempt to create a bypass was almost 8 times more likely (OR 7.6, 95% CI 2.1–27.5; p = 0.02) to result in a patent bypass than a second attempt. Administration of a small amount of heparin during the operation was also associated with bypass patency (OR 5.2, 95% CI 1.1–24.9; p = 0.04). One hundred twenty-three (77%) of the 159 bypasses were functional at patency assessments during the 1st month after the operation. Older age (OR 1.043 for every year of increase in age, 95% CI 1.010–1.076; p = 0.01), male sex (OR 2.9, 95% CI 1.3–6.5; p = 0.01), and high intraoperative bypass flow (OR 1.017 for every milliliter per minute increase in flow, 95% CI 1.004–1.030; p = 0.01) were associated with postoperative bypass patency. Conclusions Attempts to create a second EC-IC ELANA bypass after the first one are more likely to fail, whereas administration of heparin to the patient during the procedure increases the intraoperative bypass patency rate. Postoperative patency results are better in male and in older patients. Intraoperative bypass flow measurements are essential because high bypass flow is an important determinant of postoperative patency.

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Superficial Temporal Artery-to-Middle Cerebral Artery Bypass

Operative Neurosurgery ◽

10.1227/01.neu.0000144487.85531.fd ◽

2005 ◽

Vol 56 (suppl_1) ◽

pp. ONS-186-ONS-190 ◽

Cited By ~ 15

Author(s):

Fady T. Charbel ◽

Guido Meglio ◽

Sepideh Amin-Hanjani

Keyword(s):

Middle Cerebral Artery ◽

Cerebral Artery ◽

Reliable Method ◽

Artery Bypass ◽

Superficial Temporal Artery ◽

Temporal Artery ◽

Flow Measurements ◽

Blood Flow Measurements ◽

Cerebrovascular Occlusive Disease

Abstract THE SUPERFICIAL TEMPORAL artery-to-middle cerebral artery bypass represents the mainstay of bypass operations for cerebral revascularization. The role of this operation in the setting of cerebrovascular occlusive disease, with compromised cerebral hemodynamic reserve, is a topic of current investigation. In this report, we describe technical nuances to avert potential pitfalls in the performance of this procedure. The use of intraoperative quantitative blood flow measurements as a reliable method of assessing the success of the bypass is also described.

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Partition Coefficient of 133Xe between Blood and Eye Tissues

Nuklearmedizin ◽

10.1055/s-0038-1624911 ◽

1975 ◽

Vol 14 (04) ◽

pp. 301-309

Author(s):

A. Marczak ◽

A. Moszczyńska-Kowalska ◽

H. Kowalski

Keyword(s):

Partition Coefficient ◽

Aqueous Humour ◽

Vitreous Body ◽

Flow Measurements ◽

Solubility Coefficient ◽

Eye Muscles ◽

Eye Tissues ◽

Relative Solubility ◽

Blood Flow Measurements

SummaryThe relative solubility coefficient of 133Xe and the tissue-blood partition coefficient for the aqueous humour vitreous body, conjunctiva and external eye muscles of the rabbit were determined in vitro at 37° C and at various haematocrit values. The partition coefficient for haematocrit 40 was: for the aqueous humour 0,49 ml/ml, for the vitreous body 0,50 ml/ml, for the conjunctiva 0,81 ml/g and for the external eye muscles 0,77 ml/g. It was found that the solubility of 133Xe in rabbit erythrocytes is about 50 per cent higher than that in human red cells. The consequences of this fact for the precision of blood flow measurements by the method of tissue clearance are discussed.

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