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Deery HA, Liang E, Di Paolo R, Voigt K, Murray G, Siddiqui MN, Egan GF, Moran C, Jamadar SD. The association of regional cerebral blood flow and glucose metabolism in normative ageing and insulin resistance. Sci Rep 2024; 14:14574. [PMID: 38914735 PMCID: PMC11196590 DOI: 10.1038/s41598-024-65396-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 06/19/2024] [Indexed: 06/26/2024] Open
Abstract
Rising rates of insulin resistance and an ageing population are set to exact an increasing toll on individuals and society. Here we examine the contribution of age and insulin resistance to the association of cerebral blood flow and glucose metabolism; both critical process in the supply of energy for the brain. Thirty-four younger (20-42 years) and 41 older (66-86 years) healthy adults underwent a simultaneous resting state MR/PET scan, including arterial spin labelling. Rates of cerebral blood flow and glucose metabolism were derived using a functional atlas of 100 brain regions. Older adults had lower cerebral blood flow than younger adults in 95 regions, reducing to 36 regions after controlling for cortical atrophy and blood pressure. Lower cerebral blood flow was also associated with worse working memory and slower reaction time in tasks requiring cognitive flexibility and response inhibition. Younger and older insulin sensitive adults showed small, negative correlations between relatively high rates of regional cerebral blood flow and glucose metabolism. This pattern was inverted in insulin resistant older adults, who showed hypoperfusion and hypometabolism across the cortex, and a positive correlation. In insulin resistant younger adults, the association showed inversion to positive correlations, although not to the extent seen in older adults. Our findings suggest that the normal course of ageing and insulin resistance alter the rates of and associations between cerebral blood flow and glucose metabolism. They underscore the criticality of insulin sensitivity to brain health across the adult lifespan.
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Affiliation(s)
- Hamish A Deery
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia.
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia.
| | - Emma Liang
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - Robert Di Paolo
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - Katharina Voigt
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - Gerard Murray
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - M Navyaan Siddiqui
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - Gary F Egan
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia
| | - Chris Moran
- School of Public Health and Preventive Medicine, Monash University, 553 St Kilda Rd, Melbourne, VIC, 3004, Australia
| | - Sharna D Jamadar
- School of Psychological Sciences, Monash University, Wellington Rd, Melbourne, 3800, Australia.
- Monash Biomedical Imaging, Monash University, 770 Blackburn Rd, Melbourne, 3800, Australia.
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Yu J, Zhu H, Kindy MS, Taheri S. The impact of a high-sodium diet regimen on cerebrovascular morphology and cerebral perfusion in Alzheimer's disease. CEREBRAL CIRCULATION - COGNITION AND BEHAVIOR 2023; 4:100161. [PMID: 36741272 PMCID: PMC9895990 DOI: 10.1016/j.cccb.2023.100161] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 12/05/2022] [Accepted: 01/27/2023] [Indexed: 01/30/2023]
Abstract
Introduction Various lifestyle factors such as chronic hypertension and a high-sodium diet regimen are shown to impact cerebrovascular morphology and structure. Unusual cerebrovascular morphological and structural changes may contribute to cerebral hypoperfusion in Alzheimer's disease (AD). The objective of this study was to examine whether a high-sodium diet mediates cerebrovascular morphology and cerebral perfusion alterations in AD. Methods Double transgenic mice harboring Aβ precursor protein (APPswe) and presenilin-1 (PSEN1) along with wild-type controls were divided into four groups. Group A (APP/PS1) and B (controls) were both fed a high-sodium (4.00%), while group C (APP/PS1) and D (controls) were both fed a low-sodium (0.08% a regular chow diet) for three months. Then, changes in regional cerebral perfusion and diffusion, cerebrovascular morphology, and structure were quantified. Results A 3-month high-sodium diet causes pyknosis and deep staining in hippocampal neurons and reduced vascular density in both hippocampal and cortical areas (p <0.001) of APP/PS1. Despite vascular density changes, cerebral perfusion was not increased markedly (p = 0.3) in this group, though it was increased more in wild-type controls (p = 0.022). Conclusion A high-sodium diet regimen causes cerebrovascular morphology alteration in APP/PS1 mouse model of AD.
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Affiliation(s)
- Jin Yu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA
| | - Hong Zhu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA
| | - Mark S. Kindy
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA,James A. Haley VA Medical Center, Tampa, FL 33612, USA
| | - Saeid Taheri
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL 33612, USA,USF Heart Institute, Tampa, FL 33612, USA,Corresponding author at: Department of Pharmaceutical Sciences, USF Heart Institute, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 30, Tampa, FL 33612, USA.
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Hanna J, Ghazi L, Yamamoto Y, Simonov M, Shah T, Wilson FP, Peixoto AJ. Excessive Blood Pressure Response to Clonidine in Hospitalized Patients With Asymptomatic Severe Hypertension. Am J Hypertens 2022; 35:433-440. [PMID: 35038322 PMCID: PMC9088839 DOI: 10.1093/ajh/hpac004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/31/2021] [Accepted: 01/14/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND There are limited and nonconcordant data on the rapidity and safety of blood pressure response to clonidine in the setting of asymptomatic severe hypertension. We evaluated the blood pressure response to clonidine in hospitalized patients with asymptomatic severe hypertension. METHODS We performed a review of hospitalized, noncritically ill patients receiving clonidine within 6 hours of developing asymptomatic severe hypertension (systolic blood pressure [SBP] >180 or diastolic blood pressure [DBP] >110 mm Hg in the absence of acute hypertension-mediated target organ damage). The incidence of mean arterial pressure (MAP) reduction by ≥30% at 4 hours after clonidine was the primary endpoint. RESULTS We identified 200 relevant patient encounters (median age 63 years, 48.5% women). Median time to clonidine following asymptomatic severe hypertension was 2.8 hours. A total of 20 (10%) patients had ≥30% MAP reduction within 4 hours after clonidine, and 32 (16%) patients had ≥30% reduction in either SBP, DBP, or MAP. Older age, female sex, and preexisting vascular disease were associated with ≥30% MAP reductions (P < 0.05). Only patient sex and clonidine dose of 0.3 mg were significant in multivariable models. There were 14 adverse events observed within 24 hours of administration of clonidine; most (9) were acute kidney injury. There were no ischemic (myocardial, cerebrovascular) events. CONCLUSIONS A substantial minority of hospitalized patients with asymptomatic severe hypertension experience precipitous blood pressure decline with clonidine, and though blood pressure declines more precipitously in women and those receiving higher doses (0.3 mg specifically), the response to clonidine is generally not predictable on clinical grounds.
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Affiliation(s)
- Jonathan Hanna
- Department of Internal Medicine, Yale School of Medicine, Yale University, Haven, Connecticut, USA
| | - Lama Ghazi
- Department of Internal Medicine, Clinical and Translational Research Accelerator, Yale University, New Haven, Connecticut, USA
| | - Yu Yamamoto
- Department of Internal Medicine, Clinical and Translational Research Accelerator, Yale University, New Haven, Connecticut, USA
| | - Michael Simonov
- Department of Internal Medicine, Clinical and Translational Research Accelerator, Yale University, New Haven, Connecticut, USA
| | - Tayyab Shah
- Department of Internal Medicine, Yale School of Medicine, Yale University, Haven, Connecticut, USA
| | - Francis P Wilson
- Department of Internal Medicine, Clinical and Translational Research Accelerator, Yale University, New Haven, Connecticut, USA
| | - Aldo J Peixoto
- Department of Internal Medicine, Section of Nephrology, Yale School of Medicine, and the Hypertension Program, Yale New Haven Hospital Heart and Vascular Center, New Haven, Connecticut, USA
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Matsumura Y, Yamanaka T, Murai T, Fujita N, Kitahara T. Orthostatic hemodynamics in the vertebral artery and blood pressure in patients with orthostatic dizziness/vertigo. Auris Nasus Larynx 2021; 49:593-598. [PMID: 34930632 DOI: 10.1016/j.anl.2021.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/07/2021] [Accepted: 12/02/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVES Orthostatic dizziness/vertigo (ODV) is a common symptom and is believed to occur due to the cerebral hypoperfusion caused by orthostatic hypotension (OH). However, the detailed mechanism underlying ODV onset is poorly understood. The vertebral artery (VA) mainly supplies blood to the central vestibular system; therefore, the orthostatic decrease of VA blood flow could possibly lead to ODV. This study investigated the orthostatic blood pressure and VA hemodynamics in ODV patients to elucidate the hemodynamic mechanism underlying ODV onset. Furthermore, the influence of orthostatic hypotension (OH) on VA hemodynamics was examined because OH is probably the most common cause of ODV. METHODS This study included 181 patients with ODV and 73 control patients without ODV. All subjects underwent an active standing test to measure the extracranial Doppler (ECD) sonography spectrum of the VA and blood pressure (BP). VA blood flow velocity and BP were simultaneously measured for each patient in the supine static position and then in the upright standing positions following 3 min of standing. We investigated the orthostatic change in the average of flow velocity in bilateral VAs (VAFV) and BP for ODV patients compared with the control patients. RESULT VAFV in ODV patients was significantly reduced when standing up compared with the control patients. In the ODV patients, there was no difference in orthostatic decrease in VAFV between patients those with OH and without OH. However, the VAFV in the standing position was significantly lower in patients with OH than without OH. In cases with OH, the ODV patients exhibited a greater decrease in VAFV compared with the control patients, but this was not statistically significant. In the absence of OH, a significantly greater orthostatic decrease in VAFV was observed in ODV patients compared with the controls. CONCLUSION Our findings suggest that the orthostatic decrease of VA blood flow is deeply involved in the hemodynamic mechanism underlying ODV onset and is possibly associated with OH and other etiologies.
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Affiliation(s)
- Yachiyo Matsumura
- Department of Otolaryngology-Head and Neck Surgery, Nara Medical University School of Medicine Address: 840 Shijo, Kashihara Nara, 634-8522, Japan
| | - Toshiaki Yamanaka
- Department of Otolaryngology-Head and Neck Surgery, Nara Medical University School of Medicine Address: 840 Shijo, Kashihara Nara, 634-8522, Japan..
| | - Takayuki Murai
- Department of Otolaryngology-Head and Neck Surgery, Nara Medical University School of Medicine Address: 840 Shijo, Kashihara Nara, 634-8522, Japan
| | - Nobuya Fujita
- Department of Otorhinolaryngology, Osaka Kaisei Hospital, Address: 1-6-10 Miyahara, Yodogawa-ku, Osaka, 532-0003, Japan
| | - Tadashi Kitahara
- Department of Otolaryngology-Head and Neck Surgery, Nara Medical University School of Medicine Address: 840 Shijo, Kashihara Nara, 634-8522, Japan
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Affiliation(s)
- Aldo J Peixoto
- From the Department of Internal Medicine, Section of Nephrology, Yale School of Medicine, and the Hypertension Program, Yale New Haven Hospital Heart and Vascular Center, New Haven, CT
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Taheri S, Yu J, Zhu H, Kindy MS. High-Sodium Diet Has Opposing Effects on Mean Arterial Blood Pressure and Cerebral Perfusion in a Transgenic Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2018; 54:1061-1072. [PMID: 27567835 DOI: 10.3233/jad-160331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Cerebral ionic homeostasis impairment, especially Ca2+, has been observed in Alzheimer's disease (AD) and also with hypertension. Hypertension and AD both have been implicated in impaired cerebral autoregulation. However, the relationship between the ionic homeostasis impairment in AD and hypertension and cerebral blood flow (CBF) autoregulation is not clear. OBJECTIVE To test the hypothesis that a high-salt diet regimen influences the accumulation of amyloid-β (Aβand CBF) and CBF, exacerbates cognitive decline, and increases the propensity to AD. METHODS Double transgenic mice harboring the amyloid-β protein precursor (APPswe), and presenilin-1 (PSEN1) along with control littermates, 2 months of age at initiation of special diet, were divided into 4 groups: Group A, APP/PS1 and Group B, controls fed a high-sodium (4.00%) chow diet for 3 months; Group C, APP/PS1 and Group D, controls fed a low-sodium (0.08%) regular chow diet for 3 months. Mean arterial blood pressure (MAP) and CBF were measured noninvasively using the tail MAP measurement device and magnetic resonance imaging, respectively. Aβ plaques numbers in the cortex and hippocampus of APP/PS1 were quantified. RESULTS In contrary to controls, APP/PS1 mice fed a high-salt diet did not show markedly elevated mean systolic and diastolic blood pressure (134±4.8 compared with 162±2.8 mmHg, and 114±5.0 compared with 137±20 mmHg, p< 0.0001). However, a high-salt diet increased CBF in both APP/PS1 and controls and did not alter the cerebral tissue integrity. Aβ plaques were significantly reduced in the cortex and hippocampus of mice fed a high-salt diet. CONCLUSION These data suggest that a high-salt diet differently affects MAP and CBF in APP/PS1 mice and controls.
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Affiliation(s)
- Saeid Taheri
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL, USA
| | - Jin Yu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL, USA
| | - Hong Zhu
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL, USA
| | - Mark S Kindy
- Department of Pharmaceutical Sciences, University of South Florida, Tampa, FL, USA.,James A. Haley VA Medical Center, Tampa, FL, USA
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Hoshino T, Ookawara S, Goto S, Miyazawa H, Ito K, Ueda Y, Kaku Y, Hirai K, Nabata A, Mori H, Yoshida I, Tabei K. Evaluation of cerebral oxygenation in patients undergoing long-term hemodialysis. Nephron Clin Pract 2014; 126:57-61. [PMID: 24526002 DOI: 10.1159/000358432] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 01/06/2014] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND/AIMS Patients undergoing hemodialysis (HD) have higher occurrence rates of cerebral diseases, including uremic encephalopathy, cognitive impairment, dementia, and cerebrovascular disease, than the general population. During HD, ultrafiltration is performed to maintain an adequate fluid condition and is associated with subsequent blood volume (BV) reduction. We aimed to (1) monitor changes in cerebral oxygenation and BV reduction during HD, and (2) clarify the mechanism that influences cerebral oxygenation in HD patients. METHODS Eighteen HD patients and 12 healthy controls were recruited. Regional saturation of oxygen (rSO2) was continuously monitored in the frontal cortex using INVOS 5100C before, during, and after HD, and in healthy controls. Relative change in BV (%ΔBV) was simultaneously monitored during HD using a BV monitor. RESULTS Before HD, patients had significantly lower rSO2 values than controls (56.1 ± 1.4 vs. 70.4 ± 2.5%, p < 0.001). Although %ΔBV significantly decreased from 20 min to the end of HD (20 min: -3.3 ± 0.3%, p < 0.05; end of HD: -12.0 ± 1.0%, p < 0.01), changes in rSO2 values during HD were not significant. No relationship existed between rSO2 values and blood pressure levels, hemoglobin levels, oxygen pressure, HCO3(- ), oxygen saturation, and arterial O2 content before and after HD. Furthermore, changes in rSO2 were not correlated with changes in these parameters. CONCLUSION rSO2 values before HD were significantly lower in HD patients than in healthy controls. rSO2 values were maintained during HD and were not influenced by BV reduction.
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Affiliation(s)
- Taro Hoshino
- Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama City, Japan
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Salazar D, Sears BW, Aghdasi B, Only A, Francois A, Tonino P, Marra G. Cerebral desaturation events during shoulder arthroscopy in the beach chair position: patient risk factors and neurocognitive effects. J Shoulder Elbow Surg 2013; 22:1228-35. [PMID: 23415820 DOI: 10.1016/j.jse.2012.12.036] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 12/06/2012] [Accepted: 12/14/2012] [Indexed: 02/01/2023]
Abstract
BACKGROUND Patients undergoing shoulder surgery in the beach chair position may be at increased risk for serious neurocognitive complications due to cerebral ischemia. We sought to define the incidence, patient risk factors, and clinical sequelae of intraoperative cerebral desaturation events. METHODS Regional cerebral tissue oxygen saturation (rSO2) was monitored intra-operatively using near-infrared spectroscopy (NIRS) on 50 consecutive patients. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was administered to each patient pre- and postoperatively. Intra-operative decreases in rSO2 of 20% or greater were defined as cerebral desaturation events (CDE). The association between intraoperative CDE and postoperative cognitive decline was assessed. RESULTS The incidence of intraoperative CDE in our series was 18% (9/50). Increased body mass index (BMI) was found to have a statistically significant association with intraoperative CDE (mean BMI 37.32 vs 28.59, P < .0001). There was no statistical significance in pre- vs postoperative RBANS either in composite scores or any of the sub-indices in either group. CONCLUSION The degree and duration of cerebral ischemia required to produce neurocognitive dysfunction in this patient population remains undefined; however, cerebral oximetry with NIRS allows prompt identification and treatment of decreased cerebral perfusion decreasing the risk of this event. Increased BMI was found to be a statistically significant patient risk factor for the development of intra-operative CDE. The transient intra-operative CDEs were not associated with postoperative cognitive dysfunction in our patient series. We believe protocols aimed at detecting and reversing CDE minimize the risk of neurocognitive dysfunction and improve patient safety.
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Affiliation(s)
- Dane Salazar
- Department of Orthopaedic Surgery and Rehabilitation, Loyola University Health System, Maywood, IL 60153, USA.
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Fux CA, Bianchetti MG, Jakob SM, Remonda L. Reversible encephalopathy complicating post-streptococcal glomerulonephritis. Pediatr Infect Dis J 2006; 25:85-7. [PMID: 16395114 DOI: 10.1097/01.inf.0000195614.66987.2f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We describe a 15-year-old boy with acute transient encephalopathy complicating poststreptococcal glomerulonephritis. Based on advanced magnetic resonance imaging, cerebral alterations were related to cerebrovascular autoregulatory dysfunction (ie, a vasogenic edema) and vasculitis was excluded. These insights into the pathophysiology improve patient management and argue against the therapeutic immunosuppression postulated by some authors.
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Affiliation(s)
- Christoph A Fux
- Institute of Infectious Diseases, University of Bern, Bern, Switzerland.
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Kohane DS, Ingelfinger JR, Nimkin K, Wu CL. Case records of the Massachusetts General Hospital. Case 16-2005. A nine-year-old girl with headaches and hypertension. N Engl J Med 2005; 352:2223-31. [PMID: 15917388 DOI: 10.1056/nejmcpc059011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Daniel S Kohane
- Department of Pediatric Critical Care, Massachusetts General Hospital, USA
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Abstract
Postprandial hypotension is a prevalent condition in the elderly population and seems to be more common in frail elderly individuals who may be more susceptible to complications such as syncope and falls. Diagnosis is relatively easy and may be reversible in many cases. The epidemiology and pathophysiology of postprandial hypotension are not defined fully; however, a number of pathologic processes likely are involved, including abnormal sympathetic function, baroreceptor function, and vasoactive peptide release and activity. The precise relationship between symptoms and postprandial reductions in blood pressure is unclear. Blood pressure maintenance after a meal may depend on the interaction of some or all of the mechanisms outlined previously to compensate for the increase in bowel blood volume. The impairment of one or more of these mechanisms could result in inadequate compensation that leads to hypotension. If so, the presence of symptoms depends on that individual patient's ability to exercise adequate compensatory cerebral autoregulation. A hypertensive elderly patient may experience symptoms with only a small reduction in blood pressure, whereas a patient with autonomic failure may require a much larger fall in blood pressure to occur before they become symptomatic. The current definition of postprandial hypotension uses a threshold of 20 mm Hg as a cut off for diagnosis, but this may not be relevant to the presence or absence of symptoms. Further epidemiologic data are needed. Additionally, there is a lack of controlled trial evidence for the drugs that are used to treat this condition, and treatment often is carried out on a trial-and-error basis. Further research must be performed to identify the specific pathophysiology in certain patient groups, such as elderly hypertensive patients and those with autonomic failure, and to identify effective pharmacologic therapies that can be supported by randomized, placebo-controlled trials.
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Affiliation(s)
- Gerard O'Mara
- Department of Medical Gerontology, Mid Western Regional Hospital, University of Limerick, Dooradoyle, Limerick, Ireland
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Froehlich T, Sandifer S, Varma PK, Testa FM. Two cases of hypertension-induced reversible posterior leukoencephalopathy syndrome secondary to glomerulonephritis. Curr Opin Pediatr 1999; 11:512-8. [PMID: 10590909 DOI: 10.1097/00008480-199912000-00007] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- T Froehlich
- Department of Pediatrics, Children's Hospital of Pennsylvania, Philadelphia 19104, USA
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Metry G, Wikström B, Valind S, Sandhagen B, Linde T, Beshara S, Långström B, Danielson BG. Effect of normalization of hematocrit on brain circulation and metabolism in hemodialysis patients. J Am Soc Nephrol 1999; 10:854-63. [PMID: 10203371 DOI: 10.1681/asn.v104854] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Full correction of anemia with recombinant human erythropoietin (rhEPO) has been reported to reduce the risk of cardiovascular morbidity and mortality and improve the quality of life in hemodialysis (HD) patients. Effects of normalization of hematocrit on cerebral blood flow and oxygen metabolism were investigated by positron emission tomography. Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction ratio (rOER), and metabolic rate for oxygen (rCMRO2) were measured in seven HD patients before and after correction of anemia and compared with those in six healthy control subjects. In addition, blood rheology before and on rhEPO therapy was measured in HD patients, which included blood viscosity, plasma viscosity, erythrocyte fluidity, and erythrocyte aggregability. The results showed that plasma viscosity was high (1.51+/-0.19 mPa x s) and erythrocyte fluidity was low (85.8+/-4.8 Pa(-1) x s(-1)), while whole blood viscosity was within the normal range (3.72+/-0.38 mPa x s) before rhEPO therapy. After treatment, the hematocrit rose significantly from 29.3+/-3.3 to 42.4+/-2.2% (P<0.001), accompanied by a significant increase in the whole blood viscosity to 4.57+/-0.16 mPa x s, nonsignificant decrease in erythrocyte fluidity to 79.9+/-7.4 mPa(-1) x s(-1) and nonsignificant change in plasma viscosity (1.46+/-1.3 mPa x s). Positron emission tomography measurements revealed that by normalization of hematocrit, rCBF significantly decreased from 65+/-11 to 48+/-12 ml/min per 100 cm3 (P<0.05). However, arterial oxygen content (caO2) significantly increased from 5.7+/-0.7 to 8.0+/-0.4 mmol/L (P<0.0001), rOER of the hemispheres significantly increased from 44+/-3 to 51+/-6% (P<0.05) and became significantly higher than healthy control subjects (P<0.05). In addition, rCBV significantly increased from 3.5+/-0.5 to 4.6+/-0.6 ml/100 cc brain tissue. The results showed that oxygen supply to the brain tissue increased with normalization of hematocrit, but it was accompanied by increased oxygen extraction in the brain tissue. This may be assumed to be related to the decrease of erythrocyte velocity in the cerebral capillaries as a result of the decreased blood deformability and the increased plasma viscosity.
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Affiliation(s)
- G Metry
- Department of Internal Medicine, University Hospital, Uppsala, Sweden.
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Abstract
Hypertension commonly occurs in the acute period following spontaneous intracerebral hemorrhage. Management of this hypertension is controversial. Some advocate lowering blood pressure to reduce the risk of bleeding, edema formation, and systemic hypertensive complications, whereas others advocate allowing blood pressure to run its natural course as a protective measure against cerebral ischemia. This article reviews the pertinent clinical and experimental data regarding these issues and briefly discusses the use of antihypertensive agents commonly administered in this setting.
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Affiliation(s)
- R E Adams
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
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Nichols JS, Beel JA, Munro LG. Detection of impaired cerebral autoregulation using spectral analysis of intracranial pressure waves. J Neurotrauma 1996; 13:439-56. [PMID: 8880608 DOI: 10.1089/neu.1996.13.439] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Successful resuscitation following severe traumatic brain injury (TBI) requires rapid evaluation of intracranial pressure (ICP), cerebrovascular reactivity (autoregulation), and cerebral metabolism. During impaired autoregulation, inadequate cerebral blood flow (CBF) can lead to ischemia while excessive CBF can result in elevated ICP. Without information regarding the state of autoregulation, treatment of either situation may ameliorate one problem but exacerbate the other. It has been hypothesized that fast Fourier transform (FFT) analysis of arterial blood pressure (BP) and ICP waves can differentiate states of intact and impaired autoregulation. BP and ICP waves were recorded in canines before and after ischemic injury during arterial normotension, hypertension, and hypotension induced with dopamine or nitroprusside infusion. Transfer functions (TFn) were calculated from FFT spectra as ratios of ICP and BP harmonic peak amplitudes to distinguish states of vasoreactivity. During normotension and hypertension, autoregulation was intact and TF1 averaged 0.05. During hypotension, TF1 averaged 0.22 (8 x baseline, p < 0.010). During impaired autoregulation following ischemic injury, TF1 averaged 0.50 (18 x baseline, p < 0.010; 2 x nitroprusside levels, p < 0.01). This large difference in TF relative to baseline extended over a large range of BP (60 < BP < 180 mm Hg). Based on these data and previous results, it was estimated that TF can differentiate impaired autoregulation from effects solely related to elevated ICP or active vasodilation for ICP < 30-40 mm Hg. This suggests that for specific, but widely applicable physiologic conditions, spectral analysis can identify states of impaired autoregulation and, as an adjunct to traditional monitoring techniques, aid in acute resuscitation and prevention of secondary injury in TBI.
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Affiliation(s)
- J S Nichols
- Division of Neurological Surgery, Provenant Saint Anthony Central Hospital, Denver, Colorado, USA
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Rivas-Cabañero L, Rodríguez-Barbero A, Macías-Núñez JF, López-Novoa JM. Effect of felodipine on systemic hemodynamics of spontaneous mild-hypertensive aged rats. Arch Physiol Biochem 1995; 103:87-90. [PMID: 8574783 DOI: 10.3109/13813459509007569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The aim of the present study was to examine the effects of felodipine, a dihydropyridinic calcium ions channels blocker, on mean arterial blood pressure (MAP), cardiac output (CO), peripheral resistances (TPR) and blood flow distribution in spontaneously mildly hypertensive female Wistar 30-34 months old rats. Under pentobarbital anesthesia, CO and regional organ blood flow were measured by the radioactive microspheres method, before and 30 min after administration of felodipine 0.5 mumol/kg b. w. by gastric gavage. They were compared to the corresponding values in normotensive rats of the same strain and age. Fifteen (from twenty five) rats were hypertensive with a MAP averaging 139 +/- 2 mm Hg. CO and TPR were slightly higher in these hypertensive rats. Cerebral blood flow (CBF) was lower, though the difference did not reach significant values. MAP significantly decreased after felodipine with no significant changes in CO and TPR in hypertensive as well as in normotensive animals. Renal blood flow (RBF) was similar before and after felodipine which significantly decreased renal vascular resistance in both groups. Felodipine administration did not induce significant changes in CBF but a significant increase in portal venous inflow (PVI) in hypertensive rats only. In conclusion, in old female rats with mild spontaneously hypertension, acute felodipine oral administration reduced arterial blood pressure without diminishing CBF.
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Affiliation(s)
- L Rivas-Cabañero
- Instituto Reina Sofía de Investigaciones Nefrológicas, Departamento de Fisiolgía, Facultad de Medicina, Universidad de Salamanca, Spain
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Cameron OG, Modell JG, Hariharan M. Caffeine and human cerebral blood flow: a positron emission tomography study. Life Sci 1990; 47:1141-6. [PMID: 2122148 DOI: 10.1016/0024-3205(90)90174-p] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased paCO2 and increased systolic blood pressure significantly; the change in paCO2 did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed.
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Affiliation(s)
- O G Cameron
- Department of Psychiatry, University of Michigan Medical Center, Ann Arbor 48109-0722
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Abstract
Although the treatment of hypertension clearly benefits the brain in most patients, there are, however, unfortunate exceptions. Overzealous blood pressure lowering especially, and sometimes conservative blood pressure lowering, occasionally compromise the supply of blood to the brain to such an extent that neurological dysfunction or death results. Despite an awareness of this problem for more than a decade, the number of reports of such cases is increasing. An understanding of the problem requires detailed knowledge of both the pathophysiology of the cerebral circulation in hypertension and the cerebrovascular effects of antihypertensive drugs. If antihypertensive treatment, in particular emergency blood pressure lowering, is to always be safe, thought must be given to the cerebrovascular effects of the drugs to be used. This topic is discussed in relation to the observed (i.e., experimentally determined) and inferred (i.e., from clinical observation) effects of antihypertensive drugs and treatment on the cerebral circulation, especially with regard to autoregulation of cerebral blood flow.
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Affiliation(s)
- D I Barry
- Department of Psychiatry, Rigshospitalet, Copenhagen phi, Denmark
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Bowton DL, Haddon WS, Prough DS, Adair N, Alford PT, Stump DA. Theophylline effect on the cerebral blood flow response to hypoxemia. Chest 1988; 94:371-5. [PMID: 3396417 DOI: 10.1378/chest.94.2.371] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cerebral oxygen delivery (CO2D) remains nearly constant over a wide range of cerebral perfusion pressure and arterial oxygen content. In response to a decrease in arterial oxygen content secondary to hypoxemia, cerebral blood flow (CBF) increases, a response likely mediated by the release of adenosine. We studied the effect of theophylline, a potent adenosine antagonist, on CBF and cerebral oxygen delivery (CO2D) during hypoxemia in five healthy adult male volunteers. The CBF was measured using 133Xe clearance under conditions of (1) normoxemia (O2 saturation greater than 95 percent); (2) hypoxemia (O2 saturation = 80 percent); (3) normoxemia following aminophylline (the ethylene diamine salt of theophylline) 6 mg/kg intravenously; and (4) hypoxemia following aminophylline. Aminophylline decreased CBF and CO2D during both normoxemia and hypoxemia, but did not prevent the increase in CBF accompanying hypoxemia, suggesting that the increase in CBF in response to hypoxemia may not be mediated by adenosine or that customary doses of aminophylline are insufficient to inhibit adenosine-mediated cerebral vasodilation in response to hypoxemia. The significant decrease in CBF and CO2D observed following aminophylline is potentially clinically important and should be considered in the selection of bronchodilator therapy.
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Affiliation(s)
- D L Bowton
- Department of Anesthesia (Critical Care), Wake Forest University Medical Center, Winston-Salem, NC
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Prusty S, Kemper T, Moss MB, Hollander W. Occurrence of stroke in a nonhuman primate model of cerebrovascular disease. Stroke 1988; 19:84-90. [PMID: 3336906 DOI: 10.1161/01.str.19.1.84] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A relation between hypertension, atherosclerosis, and stroke is well documented in humans. We report a similar relation in two hypertensive cynomolgus monkeys with severe cerebral atherosclerosis. In our primate model hypertension is induced by surgical coarctation of the aorta. These monkeys, when fed an atherogenic diet, develop severe cerebrovascular atherosclerosis. In this setting two monkeys developed spontaneous cerebral hemispheric strokes that occurred during treatment of hypertension. Since the strokes were topographically related to severe atherosclerotic narrowing of cerebral arteries and occurred without evidence of either thrombosis or embolization, they are presumed to be related to disturbances of blood flow. In both humans and animals cerebral perfusion is autoregulated to a constant flow over a wide range of mean arterial blood pressures. In hypertension both the upper and lower limits of autoregulation are increased. With treatment of hypertension readaptation to more normal levels is reported to be inconsistent and slow to develop. It is therefore postulated that the strokes in these two monkeys were due to hypoperfusion as a result of the combination of pharmacologic reduction in blood pressure and severe occlusive atherosclerosis.
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Affiliation(s)
- S Prusty
- Boston University School of Medicine, MA 02118
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