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Liu M, Saadat N, Jeong YI, Roth S, Niekrasz M, Carroll T, Christoforidis GA. Augmentation of perfusion with simultaneous vasodilator and inotropic agents in experimental acute middle cerebral artery occlusion: a pilot study. J Neurointerv Surg 2023; 15:e69-e75. [PMID: 35803730 DOI: 10.1136/jnis-2022-018990] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/23/2022] [Indexed: 11/04/2022]
Abstract
BACKGROUND This study tests the hypothesis that simultaneous cerebral blood pressure elevation and potent vasodilation augments perfusion to ischemic tissue in acute ischemic stroke and it varies by degree of pial collateral recruitment. METHODS Fifteen mongrel canines were included. Subjects underwent permanent middle cerebral artery occlusion; pial collateral recruitment was scored before treatment. Seven treatment subjects received a continuous infusion of norepinephrine (0.1-1.52 µg/kg/min; titrated 25-45 mmHg above baseline mean arterial pressure while keeping systolic blood pressure below 180 mmHg) and hydralazine (20 mg) starting 30 min post-occlusion. Perfusion (cerebral blood flow-CBF) was evaluated with quantitative dynamic susceptibility contrast MRI 2.5 hours post-occlusion to produce images in mL/100 g/min, and relative CBF measured as ratios. Mean region of interest (ROI) values were reported, and compared and subject to regression analysis to elucidate trends. RESULTS Differences in quantitative CBF (qCBF) between treatment and control group varied by degree of pial collateral recruitment, based on Wilcoxon rank sum scores and regression model fit. For poorly collateralized subjects, ipsilateral anatomic, core infarct, and penumbra regions showed treatment with higher qCBF, raised above the ischemic threshold, compared with the control, while well collateralized subjects showed a paradoxical decrease maintained above the ischemic threshold for neuronal death. qCBF on the contralateral side increased regardless of collateralization. CONCLUSION Results suggest that perfusion can be augmented in ischemic stroke with norepinephrine and hydralazine. Perfusion augmentation depends on degree of collateralization and territory in question, with some evidence of vascular steal.
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Affiliation(s)
- Mira Liu
- University of Chicago Department of Radiology, Chicago, Illinois, USA
| | - Niloufar Saadat
- University of Chicago Department of Radiology, Chicago, Illinois, USA
| | - Yong Ik Jeong
- University of Chicago Department of Radiology, Chicago, Illinois, USA
| | - Steven Roth
- Anesthesiology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Marek Niekrasz
- Animal Research Center, The University of Chicago Medicine, Chicago, Illinois, USA
| | - Timothy Carroll
- University of Chicago Department of Radiology, Chicago, Illinois, USA
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Saadat N, Christoforidis GA, Jeong YI, Liu M, Dimov A, Roth S, Niekrasz M, Ansari SA, Carroll T. Influence of simultaneous pressor and vasodilatory agents on the evolution of infarct growth in experimental acute middle cerebral artery occlusion. J Neurointerv Surg 2020; 13:741-745. [PMID: 32900906 DOI: 10.1136/neurintsurg-2020-016539] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/13/2020] [Accepted: 08/16/2020] [Indexed: 11/04/2022]
Abstract
BACKGROUND This study sought to test the hypothesis that simultaneous central blood pressure elevation and potent vasodilation can mitigate pial collateral-dependent infarct growth in acute ischemic stroke. METHODS Twenty mongrel canines (20-30 kg) underwent permanent middle cerebral artery occlusion (MCAO). Eight subjects received continuous infusion of norepinephrine (0.1-1.5200 µg/kg/min; titrated to a median of 34 mmHg above baseline mean arterial pressure) and hydralazine (20 mg) starting 30 min following MCAO. Pial collateral recruitment was scored prior to treatment and used to predict infarct volume based on a previously reported parameterization. Serial diffusion magnetic resonance imaging (MRI) acquisitions tracked infarct volumes over a 4-hour time frame. Infarct volumes and infarct volume growth between treatment and control groups were compared with each other and to predicted values. Fluid-attenuated inversion recovery (FLAIR) MRI, susceptibility weighted imaging (SWI), and necropsy findings were included in the evaluation. RESULTS Differences between treatment and control group varied by pial collateral recruitment based on indicator-variable regression effects analysis with interaction confirmed by regression model fit. Benefit in treatment group was only in subjects with poor collaterals which had 35.7% less infarct volume growth (P=0.0008; ANOVA) relative to controls. Measured infarct growth was significantly lower than predicted by the model (linear regression partial F-test, slope P<0.001, intercept=0.003). There was no evidence for cerebral hemorrhage or posterior reversible encephalopathy syndrome. CONCLUSION Our results indicate that a combination of norepinephrine and hydralazine administered in the acute phase of ischemic stroke mitigates infarct evolution in subjects with poor but not good collateral recruitment.
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Affiliation(s)
| | | | - Yong Ik Jeong
- Radiology, University of Chicago, Chicago, Illinois, USA
| | - Mira Liu
- Radiology, University of Chicago, Chicago, Illinois, USA
| | - Alexey Dimov
- Radiology, University of Chicago, Chicago, Illinois, USA
| | - Steven Roth
- Anesthesiology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Marek Niekrasz
- Animal Research Center, University of Chicago, Chicago, Illinois, USA
| | - Sameer A Ansari
- Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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Christoforidis GA, Saadat N, Kontzialis M, Karakasis CJ, Slivka AP. Predictors for the extent of pial collateral recruitment in acute ischemic stroke. Neuroradiol J 2020; 33:98-104. [PMID: 31896284 DOI: 10.1177/1971400919897389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Pial arterioles can provide a variable degree of collateral flow to ischemic vascular territories during acute ischemic stroke. This study sought to identify predictive factors of the degree of pial collateral recruitment in acute ischemic stroke. METHODS Clinical information and arteriograms from 62 consecutive patients with stroke due to either middle cerebral artery (MCA) M1 segment or internal carotid artery (ICA) terminus occlusion within 6 h following symptom onset were retrospectively reviewed. Pial collaterals were defined based on the extent of reconstitution of the MCA territory. Patients with slow antegrade flow distal to the occlusion site were excluded and no anesthetics were used prior or during angiography. Results were analyzed using multivariate nominal logistic regression. RESULTS Better pial collateral recruitment was associated with proximal MCA versus ICA terminus occlusion (p = 0.005; odds ratio (OR) = 9.3; 95% confidence interval (CI), 2.16-53.3), lower presenting National Institutes of Health Stroke Scale Score (NIHSSS) (p = 0.023; OR = 6.51; 95% CI, 1.49-41.7), and lower diastolic blood pressure (p = 0.0411; OR = 5.05; 95% CI, 1.20-29.2). Age, gender, symptom duration, diabetes, laterality, systolic blood pressure, glucose level, hematocrit, platelet level, and white blood cell count at presentation were not found to have a statistically significant association with pial collateral recruitment. CONCLUSIONS Extent of pial collateral recruitment is strongly associated with the occlusion site (MCA M1 segment versus ICA terminus) and less strongly associated with presenting NIHSSS and diastolic blood pressure.
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Ginsberg MD. The cerebral collateral circulation: Relevance to pathophysiology and treatment of stroke. Neuropharmacology 2017; 134:280-292. [PMID: 28801174 DOI: 10.1016/j.neuropharm.2017.08.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 07/28/2017] [Accepted: 08/06/2017] [Indexed: 12/29/2022]
Abstract
The brain's collateral circulation consists of arterial anastomotic channels capable of providing nutrient perfusion to brain regions whose normal sources of flow have become compromised, as occurs in acute ischemic stroke. Modern CT-based neuroimaging is capable of providing detailed information as to collateral extent and sufficiency and is complemented by magnetic resonance-based methods. In the present era of standard-of-care IV thrombolysis for acute ischemic stroke, and following the recent therapeutic successes of randomized clinical trials of acute endovascular intervention, the sufficiency of the collateral circulation has been convincingly established as a key factor influencing the likelihood of successful reperfusion and favorable clinical outcome. This article reviews the features of the brain's collateral circulation; methods for its evaluation in the acute clinical setting; the relevance of collateral circulation to prognosis in acute ischemic stroke; the specific insights into the collateral circulation learned from recent trials of endovascular intervention; and the major influence of genetic factors. Finally, we emphasize the need to develop therapeutic approaches to augment collateral perfusion as an adjunctive strategy to be employed along with, or prior to, thrombolysis and endovascular interventions, and we highlight the possible potential of inhaled nitric oxide, albumin, and other approaches. This article is part of the Special Issue entitled 'Cerebral Ischemia'.
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Affiliation(s)
- Myron D Ginsberg
- Department of Neurology, University of Miami Miller School of Medicine, Clinical Research Center, Room 1331, 1120 NW 14th Street, Miami, FL 33136, USA.
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Ginsberg MD. Expanding the concept of neuroprotection for acute ischemic stroke: The pivotal roles of reperfusion and the collateral circulation. Prog Neurobiol 2016; 145-146:46-77. [PMID: 27637159 DOI: 10.1016/j.pneurobio.2016.09.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/22/2016] [Accepted: 09/10/2016] [Indexed: 12/27/2022]
Abstract
This review surveys the efforts taken to achieve clinically efficacious protection of the ischemic brain and underscores the necessity of expanding our purview to include the essential role of cerebral perfusion and the collateral circulation. We consider the development of quantitative strategies to measure cerebral perfusion at the regional and local levels and the application of these methods to elucidate flow-related thresholds of ischemic viability and to characterize the ischemic penumbra. We stress that the modern concept of neuroprotection must consider perfusion, the necessary substrate upon which ischemic brain survival depends. We survey the major mechanistic approaches to neuroprotection and review clinical neuroprotection trials, focusing on those phase 3 multicenter clinical trials for acute ischemic stroke that have been completed or terminated. We review the evolution of thrombolytic therapies; consider the lessons learned from the initial, negative multicenter trials of endovascular therapy; and emphasize the highly successful positive trials that have finally established a clinical role for endovascular clot removal. As these studies point to the brain's collateral circulation as key to successful reperfusion, we next review the anatomy and pathophysiology of collateral perfusion as it relates to ischemic infarction, as well as the molecular and genetic influences on collateral development. We discuss the current MR and CT-based diagnostic methods for assessing the collateral circulation and the prognostic significance of collaterals in ischemic stroke, and we consider past and possible future therapeutic directions.
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Affiliation(s)
- Myron D Ginsberg
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, United States.
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Ono M, Zheng Y, Joshi B, Sigl JC, Hogue CW. Validation of a stand-alone near-infrared spectroscopy system for monitoring cerebral autoregulation during cardiac surgery. Anesth Analg 2012; 116:198-204. [PMID: 23223100 DOI: 10.1213/ane.0b013e318271fb10] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Individualizing arterial blood pressure (ABP) targets during cardiopulmonary bypass (CPB) based on cerebral blood flow (CBF) autoregulation monitoring may provide a more effective means for preventing cerebral hypoperfusion than the current standard of care. Autoregulation can be monitored in real time with transcranial Doppler (TCD). We have previously demonstrated that near-infrared spectroscopy (NIRS)-derived regional cerebral oxygen saturation (rS(c)O(2)) provides a clinically suitable surrogate of CBF for autoregulation monitoring. The purpose of this study was to determine the accuracy of a stand-alone "plug-and-play" investigational system for autoregulation monitoring that uses a commercially available NIRS monitor with TCD methods. METHODS TCD monitoring of middle cerebral artery CBF velocity and NIRS monitoring were performed in 70 patients during CPB. Indices of autoregulation were computed by both a personal computer-based system and an investigational prototype NIRS-based monitor. A moving linear correlation coefficient between slow waves of ABP and CBF velocity (mean velocity index [Mx]) and between ABP and rS(c)O(2) (cerebral oximetry index [COx]) were calculated. When CBF is autoregulated, there is no correlation between CBF and ABP; when CBF is dysregulated, Mx and COx approach 1 (i.e., CBF and ABP are correlated). Linear regression and bias analysis were performed between time-averaged values of Mx and COx derived from the personal computer-based system and from COx measured with the prototype monitor. Values for Mx and COx were categorized in 5 mm Hg bins of ABP for each patient. The lower limit of CBF autoregulation was defined as the ABP where Mx incrementally increased to ≥0.4. RESULTS There was correlation and good agreement between COx derived from the prototype monitor and Mx (r = 0.510; 95% confidence interval, 0.414-0.595; P < 0.001; bias, -0.07 ± 0.19). The correlation and bias between the personal computer-based COx and the COx from the prototype NIRS monitor were r = 0.957 (95% confidence interval, 0.945-0.966; P < 0.001 and 0.06 ± 0.06, respectively). The average ABP at the lower limit of autoregulation was 63 ± 11 mm Hg (95% prediction interval, 52-74 mm Hg). Although the mean ABP at the COx-determined lower limit of autoregulation determined with the prototype monitor was statistically different from that determined by Mx (59 ± 9 mm Hg; 95% prediction interval, 50-68 mm Hg; P = 0.026), the difference was not likely clinically meaningful. CONCLUSIONS Monitoring CBF autoregulation with an investigational stand-alone NIRS monitor is correlated and in good agreement with TCD-based methods. The availability of such a device would allow widespread autoregulation monitoring as a means of individualizing ABP targets during CPB.
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Affiliation(s)
- Masahiro Ono
- Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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Charlson ME, Peterson JC, Krieger KH, Hartman GS, Hollenberg JP, Briggs WM, Segal AZ, Parikh M, Thomas SJ, Donahue RG, Purcell MH, Pirraglia PA, Isom OW. Improvement of Outcomes after Coronary Artery Bypass II: A Randomized Trial Comparing Intraoperative High Versus Customized Mean Arterial Pressure. J Card Surg 2007; 22:465-72. [DOI: 10.1111/j.1540-8191.2007.00471.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Hogue CW, Palin CA, Arrowsmith JE. Cardiopulmonary bypass management and neurologic outcomes: an evidence-based appraisal of current practices. Anesth Analg 2006; 103:21-37. [PMID: 16790619 DOI: 10.1213/01.ane.0000220035.82989.79] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Neurologic complications after cardiac surgery are of growing importance for an aging surgical population. In this review, we provide a critical appraisal of the impact of current cardiopulmonary bypass (CPB) management strategies on neurologic complications. Other than the use of 20-40 microm arterial line filters and membrane oxygenators, newer modifications of the basic CPB apparatus or the use of specialized equipment or procedures (including hypothermia and "tight" glucose control) have unproven benefit on neurologic outcomes. Epiaortic ultrasound can be considered for ascending aorta manipulations to avoid atheroma, although available clinical trials assessing this maneuver are limited. Current approaches for managing flow, arterial blood pressure, and pH during CPB are supported by data from clinical investigations, but these studies included few elderly or high-risk patients and predated many other contemporary practices. Although there are promising data on the benefits of some drugs blocking excitatory amino acid signaling pathways and inflammation, there are currently no drugs that can be recommended for neuroprotection during CPB. Together, the reviewed data highlight the deficiencies of the current knowledge base that physicians are dependent on to guide patient care during CPB. Multicenter clinical trials assessing measures to reduce the frequency of neurologic complications are needed to develop evidence-based strategies to avoid increasing patient morbidity and mortality.
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Affiliation(s)
- Charles W Hogue
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University Medical School, 600 North Wolfe Street, Tower 711, Baltimore, MD 21205, USA.
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DiNardo JA, Wegner JA. Pro: low-flow cardiopulmonary bypass is the preferred technique for patients undergoing cardiac surgical procedures. J Cardiothorac Vasc Anesth 2001; 15:649-51. [PMID: 11688010 DOI: 10.1053/jcan.2001.26550] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- J A DiNardo
- Department of Anesthesia, Cardiac Anesthesia Service, Children's Hospital, Boston, MA, USA.
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Plestis KA, Gold JP. Importance of blood pressure regulation in maintaining adequate tissue perfusion during cardiopulmonary bypass. Semin Thorac Cardiovasc Surg 2001; 13:170-5. [PMID: 11494208 DOI: 10.1053/stcs.2001.24071] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Patients undergoing surgery with the aid of cardiopulmonary bypass (CPB) have an incidence of end-organ dysfunction, caused by embolization, regional hypoperfusion, or some combination of the two. In this article, we attempt to define the effect of mean arterial pressure (MAP) during CPB on postoperative end-organ function. Although early studies reported that cerebral perfusion during hypothermic CPB is independent of MAP, recent laboratory and clinical reports have shown a positive slope in the MAP versus cerebral blood flow relationship. In clinical studies, patients who had higher MAPs during CPB had a lower incidence of cardiac and neurologic complications, as well as late neurocognitive abnormalities compared with patients with lower MAPs. Improving collateral flow in the setting of cerebral embolization has been postulated as the main mechanism for the improved neurologic outcomes in the high MAP groups. Higher perfusion pressure during CPB affects regional blood flow to the kidneys and visceral organs. However, the lower autoregulatory limits of perfusion to abdominal organs differ from the limits to the brain. Enhanced visceral perfusion during CPB is best achieved by increasing perfusion pressure via increases in perfusion flow rates rather than by using peripheral vasoconstriction alone. In conclusion, it is clear that maintenance of a high MAP during CPB may have a significant impact in protecting the brain and abdominal organs, particularly in the subset of patients at high risk for embolization and end-organ dysfunction.
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Affiliation(s)
- K A Plestis
- Department of Cardiovascular and Thoracic Surgery, The Albert Einstein College of Medicine-Montefiore Medical Center, Bronx, NY, USA
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Sungurtekin H, Boston US, Orszulak TA, Cook DJ. Effect of cerebral embolization on regional autoregulation during cardiopulmonary bypass in dogs. Ann Thorac Surg 2000; 69:1130-4. [PMID: 10800806 DOI: 10.1016/s0003-4975(99)01576-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Embolization during cardiopulmonary bypass probably alters cerebral autoregulation. Therefore, using laser Doppler flowmetry we investigated the cerebral blood flow velocity changes in response to changes in arterial pressure, before and after embolization in a canine bypass model. METHODS After Institutional Animal Care and Use Committee approval, 8 anesthetized dogs had a laser Doppler flow probe positioned over the temporoparietal dura. During 37 degrees C cardiopulmonary bypass, the cerebral blood flow velocity response to changing mean arterial pressure (40 to 85 mm Hg in random order) was assessed before and after systemic embolization of 100 mg of 97-microm latex microspheres. RESULTS Before embolization, cerebral blood flow velocity increased 39% as mean arterial pressure increased from 40 to 85 mm Hg. Following embolization, a 94% increase in cerebral blood flow velocity was demonstrated over the same mean arterial pressure range. The slopes of the curves relating cerebral blood flow velocity to mean arterial pressure were 0.21+/-0.74 and 1.31+/-0.87, before and after embolization (p = 0.016) respectively. CONCLUSIONS Regional cerebral blood flow autoregulation may be impaired by microembolization known to occur during cardiopulmonary bypass, increasing the dependence of cerebral blood flow on mean arterial pressure.
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Affiliation(s)
- H Sungurtekin
- Department of Anesthesiology, Mayo Foundation and Mayo Clinic, Rochester, Minnesota 55905, USA
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Robertson SC, Brown P, Loftus CM. Effects of etomidate administration on cerebral collateral flow. Neurosurgery 1998; 43:317-23; discussion 323-4. [PMID: 9696085 DOI: 10.1097/00006123-199808000-00085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE Augmentation of blood flow to collateral-dependent tissue (CDT) as a result of selective vasodilation of collateral vessels has been shown to occur with various stimuli after middle cerebral artery occlusion. Etomidate, a carboxylated imidazole derivative, is a nonbarbiturate anesthetic that is used clinically both as an anesthetic and as a neuroprotective agent. The effect etomidate has on collateral cerebral vessels is unknown. The purpose of our studies was to test whether etomidate selectively augmented cerebral blood flow (CBF) to CDT during ischemia as an additional mechanism of neuroprotection. METHODS A left craniotomy was performed in each of 14 dogs, with the animals under halothane anesthesia. A branch of the middle cerebral artery was occluded and cannulated distally for determination of CDT using a "shadow flow" technique. CBF and vascular pressures were measured and used to calculate vascular resistance. An etomidate infusion (0.1 mg/kg of body weight/min administered intravenously) was started, and CBF and vascular pressures were measured at 10 and 40 minutes. Hypotension was then induced, and CBF and pressures were again measured. RESULTS CBF was significantly reduced in all regions of the brain, including CDT, when etomidate was infused. CDT showed a 53.7% reduction in flow, whereas normal CBF was reduced by at least 63.4%. During hypotension, blood flow to CDT was reduced by an additional 42.7%, whereas normal cerebrum was reduced by at least 22.7%. Vascular resistance was increased in all vessels during etomidate infusion. CONCLUSION The neuroprotective effects of etomidate do not seem to be through the augmentation of collateral or global CBF.
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Affiliation(s)
- S C Robertson
- Division of Neurosurgery, University of Iowa College of Medicine and Veterans Administration Medical Center, Iowa City 52242, USA
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Plöchl W, Cook DJ, Orszulak TA, Daly RC. Critical cerebral perfusion pressure during tepid heart operations in dogs. Ann Thorac Surg 1998; 66:118-23; discussion 124. [PMID: 9692450 DOI: 10.1016/s0003-4975(98)00355-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND The management of blood pressure during cardiopulmonary bypass varies widely. This may be particularly relevant with the trend to warmer bypass temperatures and an older patient population. Therefore, we examined the minimal perfusion pressure that maintains cerebral oxygen delivery during cardiopulmonary bypass at 33 degrees C. METHODS Ten dogs were placed on bypass and body temperature was reduced to 33 degrees C (alpha-stat pH management). At six randomly ordered mean arterial blood pressures (35, 40, 45, 50, 60, and 70 mm Hg), cerebral blood flow, oxygen delivery, and metabolic rate were determined. RESULTS Cerebral oxygen delivery was stable if the mean arterial pressure was greater than or equal to 60 mm Hg. If mean arterial pressure was less than or equal to 50 mm Hg, cerebral oxygen delivery decreased, and at less than 45 mm Hg cerebral ischemia was seen. CONCLUSIONS In a dog without vascular disease, the brain becomes perfusion pressure-dependent at a mean arterial pressure of approximately 50 mm Hg. There is no leftward shift of the cerebral autoregulatory curve during bypass at 33 degrees C. Greater support of mean arterial pressure during "tepid" cardiopulmonary bypass is indicated in the current adult surgical population that is older and has vascular comorbidity.
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Affiliation(s)
- W Plöchl
- Department of Anesthesiology, Mayo Foundation and Mayo Clinic, Rochester, Minnesota 55905, USA
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Hartman G. Pro: during cardiopulmonary bypass for elective coronary artery bypass grafting, perfusion pressure should routinely be greater than 70 mmHg. J Cardiothorac Vasc Anesth 1998; 12:358-60. [PMID: 9636924 DOI: 10.1016/s1053-0770(98)90022-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- G Hartman
- Cornell University Medical Center, Dept of Anesthesiology, New York, NY 10021, USA
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Gao E, Young WL, Pile-Spellman J, Ornstein E, Ma Q. Mathematical considerations for modeling cerebral blood flow autoregulation to systemic arterial pressure. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H1023-31. [PMID: 9530217 DOI: 10.1152/ajpheart.1998.274.3.h1023] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The shape of the autoregulation curve for cerebral blood flow (CBF) vs. pressure is depicted in a variety of ways to fit experimentally derived data. However, there is no general empirical description to reproduce CBF changes resulting from systemic arterial pressure variations that is consistent with the reported data. We analyzed previously reported experimental data used to construct autoregulation curves. To improve on existing portrayals of the fitting of the observed data, a compartmental model was developed for synthesis of the autoregulation curve. The resistive arterial and arteriolar network was simplified as an autoregulation device (ARD), which consists of four compartments in series controlling CBF. Each compartment consists of a group of identical vessels in parallel. The response of each vessel category to changes in perfusion pressure was simulated using reported experimental data. The CBF-pressure curve was calculated from the resistance of the ARD. The predicted autoregulation curve was consistent with reported experimental data. The lower and upper limits of autoregulation (LLA and ULA) were predicted as 69 and 153 mmHg, respectively. The average value of the slope of the CBF-pressure curve below LLA and beyond ULA was predicted as 1.3 and 3.3% change in CBF per mmHg, respectively. Our four-compartment ARD model, which simulated small arteries and arterioles, predicted an autoregulation function similar to experimental data with respect to the LLA, ULA, and average slopes of the autoregulation curve below LLA and above ULA.
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Affiliation(s)
- E Gao
- Department of Electrical Engineering, Columbia University, New York, New York 10032, USA
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Robertson SC, Loftus CM. Effect of N-methyl-D-aspartate and inhibition of neuronal nitric oxide on collateral cerebral blood flow after middle cerebral artery occlusion. Neurosurgery 1998; 42:117-23; discussion 123-4. [PMID: 9442512 DOI: 10.1097/00006123-199801000-00023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVE To study the role of N-methyl-D-aspartate (NMDA) receptor activation and selective inhibition of neuronal nitric oxide synthase with 7-nitroindazole (7-NI) on blood flow to collateral-dependent tissue (CDT) after middle cerebral artery (MCA) occlusion. METHODS A left craniotomy was performed in each of 11 dogs with the animals under halothane anesthesia. A branch of the MCA was occluded and cannulated distally for determination of CDT, using a "shadow flow" technique. Cerebral blood flow (CBF) and vascular pressures were measured and used to calculate vascular resistance. TECHNIQUE Our shadow flow model has the ability to identify an area of CDT, with minimal contamination from overlap flow within a morphologically identified "risk area" for MCA branch occlusion. RESULTS NMDA increased blood flow to CDT by 56.2%, while normal ipsilateral and contralateral cerebrum increased by at least 35% from baseline. 7-NI caused a significant drop in regional CBF, with the greatest drop of 41.7% occurring in the CDT. Normal ipsilateral and contralateral CBF was reduced by 31.7 and 23.9%, respectively. The dilator response to NMDA was significantly attenuated after 7-NI administration, except in CDT where flow increased ("inverse steal"). Cerebral vascular resistance decreased in response to NMDA and increased with 7-NI. CONCLUSION Neuronal nitric oxide production seems to play an important role in regulating vascular tone and CBF to CDT after MCA occlusion. Selective preservation of blood flow to CDT seems to be mediated by NMDA receptor activation but independent of neuronal nitric oxide production.
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Affiliation(s)
- S C Robertson
- Division of Neurosurgery, University of Iowa College of Medicine, Iowa City, USA
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Robertson SC, Wetjen NM, Beer BJ, Loftus CM. Pre- and postischemic effects of the NMDA receptor antagonist dizocilpine maleate (MK-801) on collateral cerebral blood flow. J Neurosurg 1997; 87:927-33. [PMID: 9384406 DOI: 10.3171/jns.1997.87.6.0927] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The authors studied the effects of pre- and postischemic administration of dizocilpine maleate (MK-801) on collateral and regional cerebral blood flow (CBF). The ischemic penumbra appears to benefit most from the neuroprotective effects of MK-801. The precise mechanism by which MK-801 provides this neuroprotection remains controversial. Alterations in CBF have been demonstrated with MK-801 administration, but whether the response is an increase or decrease in flow has remained unclear. A left-sided craniectomy was performed in 20 dogs. A branch of the middle cerebral artery (MCA) was cannulated and collateral blood supply-dependent tissue (CDT) was identified using the "shadow flow" technique. Regional CBF was measured using radiolabeled microspheres. Six dogs received MK-801 (1 mg/kg administered intravenously) before they underwent MCA branch occlusion; the remaining 14 dogs received MK-801 after they underwent MCA occlusion. Cerebral blood flow and vascular pressures were measured 30 and 60 minutes after MK-801 administration. In animals that received MK-801 before MCA occlusion, CBF did not change significantly from baseline values before or after occlusion. In contrast, in animals that received MK-801 after MCA occlusion, CBF was significantly reduced in all regions of the brain, including the CDT. Collateral blood supply-dependent tissue showed a 51.7% reduction in flow, whereas normal CBF was reduced by 29.7%. The MK-801 induced cerebral vasoconstriction in both groups. The neuroprotective effects of MK-801 do not appear to be caused by the augmentation of collateral or global cerebral circulation and, in fact, may block the glutamate-mediated vasodilation that occurs during ischemia.
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Affiliation(s)
- S C Robertson
- Division of Neurosurgery, University of Iowa College of Medicine, Iowa City 52242, USA
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Muhonen MG, Robertson SC, Gerdes JS, Loftus CM. Effects of serotonin on cerebral circulation after middle cerebral artery occlusion. J Neurosurg 1997; 87:301-6. [PMID: 9254097 DOI: 10.3171/jns.1997.87.2.0301] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Serotonin (5-HT) produces constriction of peripheral collateral blood vessels. Using an animal model, the authors tested the hypothesis that 5-HT constricts collateral vessels in the cerebrum. A branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally in anesthetized dogs. Blood flow to the area at risk for infarction was detected by perfusing the cannulated MCA branch with microsphere-free blood during systemic injection of radioactive microspheres (shadow flow technique). Blood flow to collateral-dependent and normal cerebrum was measured during intravenous infusion of 5-HT (10 and 40 mg/kg/minute). Serotonin produced a dose-related reduction of blood flow to collateral-dependent cerebrum, increased collateral vessel resistance in large cerebral arteries and collateral vessels, and decreased cerebral artery perfusion pressure. In contrast, blood flow to normal cerebrum was not altered because a decrease in small vessel resistance effectively compensated for a decrease in MCA perfusion pressure. These findings indicate that 5-HT produces constriction of collateral vessels in the cerebrum. This response is clearly different from normal small cerebral vessels, which dilate during 5-HT infusion.
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Affiliation(s)
- M G Muhonen
- Division of Neurosurgery, University of Iowa College of Medicine, Iowa City 52242, USA
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Babikian VL, Schwarze JJ, Cantelmo NL, Pochay V, Winter M. Collateral flow changes through the anterior communicating artery during carotid endarterectomy. J Neurol Sci 1996; 138:53-9. [PMID: 8791239 DOI: 10.1016/0022-510x(95)00348-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To evaluate early changes in collateral flow through the anterior communicating artery, 11 patients undergoing carotid endarterectomy were monitored. All had angiographically demonstrated collateral flow towards the hemisphere on the side of surgery. The middle cerebral artery ipsilateral to the operated side and the contralateral anterior cerebral artery were simultaneously insonated with a transcranial Doppler instrument equipped with dual transducers, and flow velocity values were obtained at specific surgical stages. Mean flow velocity in the contralateral anterior cerebral artery's A1 segment increased at clamp placement (p = 0.036), did not change during clamping, and decreased at clamp release (p = 0.004). The rise in velocity occurred within seconds of clamp placement in all patients with an increase, reaching the 10 cm/s threshold within 1 min. No consistent increase was detected after 5 min. A decrease in pulsatility index, indicating a drop in resistance, was detected at clamp placement in the middle cerebral artery on the side of surgery (p = 0.012). The index did not change during clamping, but increased at clamp release (p = 0.002). Our findings indicate that significant changes in anterior communicating artery collateral flow occur during carotid endarterectomy, starting within seconds of carotid artery clamping. These changes are associated with arterial resistance alterations in the territory of the middle cerebral artery on the endarterectomy side. Our observations should be useful to assess intracranial early collateral flow changes in surgical and non-surgical settings.
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Affiliation(s)
- V L Babikian
- Department of Neurology, Boston University School of Medicine, MA, USA
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Muhonen MG, Loftus CM, Heistad DD. Effects of adenosine and 2-chloroadenosine on cerebral collateral vessels. J Cereb Blood Flow Metab 1995; 15:1075-81. [PMID: 7593340 DOI: 10.1038/jcbfm.1995.134] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Adenosine is a potent cerebral vasodilator. We tested the hypothesis that dilatation of collateral vessels in cerebrum, in response to topical adenosine and 2-chloroadenosine (2-CAD), would increase blood flow to collateral-dependent cerebrum. In dogs anesthetized with halothane, a branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally. The collateral-dependent area at risk for infarction was perfused from a reservoir with microsphere-free blood, and blood flow to normal cerebrum and to cerebrum dependent on collateral flow was measured with radioactive microspheres injected into the left ventricle through a femoral artery catheter. Perfusion through the cannulated MCA branch was stopped, and flow to normal and collateral-dependent cerebrum was measured after adenosine (10(-2) M) or 2-CAD (10(-4) M) was added to the superfusate over the cerebrum. In normal cerebrum, topical application of adenosine increased flow to outer but not inner layers. Topical application of adenosine had little effect on flow to collateral-dependent tissue. In normal cerebrum, 2-CAD increased flow to outer layers, whereas flow to inner layers tended to increase. During 2-CAD, flow to outer cortical layers of collateral-dependent cerebrum increased from 140 +/- 20 ml/100 g/min (mean +/- SD) to 231 +/- 68, whereas flow to the inner collateral-dependent tissue did not change. The findings indicate that, after occlusion of a cerebral artery, topical 2-CAD increases blood flow to outer layers of collateral-dependent and normal cerebrum.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M G Muhonen
- Department of Surgery (Division of Neurosurgery), University of Iowa College of Medicine, Iowa City 52242, USA
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Muhonen MG, Heistad DD, Faraci FM, Loftus CM. Augmentation of blood flow through cerebral collaterals by inhibition of nitric oxide synthase. J Cereb Blood Flow Metab 1994; 14:704-14. [PMID: 7520451 DOI: 10.1038/jcbfm.1994.91] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We examined the influence of nitric oxide (NO) on normal and collateral cerebral blood flow after occlusion of the middle cerebral artery (MCA). Effects of NG-nitro-L-arginine (nitroarginine), an inhibitor of NO synthase, were examined during normotension and hypotension (arterial pressure, 50 mm Hg) in 49 anesthetized dogs. Following a craniotomy, a branch of the MCA was cannulated, and collateral-dependent tissue was identified using the shadow-flow technique. Regional cerebral blood flow was measured with microspheres, and pial artery pressure was measured with a micropipette. Intravenous nitroarginine reduced blood flow to normal cerebrum by approximately 40% (p < 0.05) during normotension and hypotension, with aortic pressure maintained constant after nitroarginine administration. Injection of nitroarginine during hypotension, without control of pressor effects, increased aortic and pial artery pressure approximately twofold. Concurrently, blood flow to normal cerebrum decreased (p < 0.05), while flow to collateral-dependent cerebrum increased (p < 0.05). Phenylephrine was infused during hypotension to increase arterial pressure to values similar to those achieved following nitroarginine. Blood flow to collateral-dependent cerebrum increased (p < 0.05), but flow to normal cerebrum was not altered during infusion of phenylephrine. Thus, inhibition of NO synthase during hypotension increases arterial pressure, decreases blood flow to normal cerebrum, and increases blood flow to collateral-dependent cerebrum. Phenylephrine also increases perfusion pressure and blood flow to collateral-dependent cerebrum, but in contrast to nitroarginine, it does not redistribute blood flow from normal cerebrum.
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Affiliation(s)
- M G Muhonen
- Division of Neurosurgery (Department of Surgery), University of Iowa College of Medicine, Iowa City 52242
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