Gao Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 191-194). / Abstracts in English and Chinese. / Abstract in English --- p.i / Abstract in Chinese --- p.iii / Acknowledgement --- p.v / Introduction --- p.vi / Contents --- p.viii / List of tables --- p.xiv / List of figures --- p.xv / Chapter Chapter One --- Literature Review / Chapter 1.1 --- Middle Cerebral Artery (MCA) Stenos --- p.is / Chapter 1.1.1 --- Prevalence of atherosclerotic MCA stenosis --- p.2 / Chapter 1.1.2 --- Methods for diagnosis of MCA stenosis --- p.3 / Chapter 1.1.3 --- Possible mechanism and course of stroke with MCA stenosis --- p.4 / Chapter 1.1.4 --- Treatment and prevention of stroke in patients with MCA stenosis --- p.5 / Chapter 1.2 --- Microembolic Signal (MES) Detection / Chapter 1.2.1 --- Introduction --- p.9 / Chapter 1.2.2 --- Technology --- p.9 / Characteristics of MES / Factors that affect MES detection / Problems of technology / Chapter 1.2.3 --- Clinical application --- p.15 / MES originating from atherosclerotic carotid artery stenosis / MES detection in internal carotid endarterectomy (CEA) / MES detection in patients with MCA stenosis / Predicting value and application in therapeutic trial / References --- p.19 / Chapter Chapter Two --- General Methodology / Chapter 2.1 --- Transcranial Doppler (TCD) Diagnosis for Intracranial Artery Stenosis / Chapter 2.1.1 --- TCD spectrum and common parameters --- p.29 / Chapter 2.1.2 --- Emitting and receiving transducers --- p.29 / Chapter 2.1.3 --- Pulsitility index (PI) --- p.31 / Chapter 2.1.4 --- Insonation depth and flow direction --- p.31 / Chapter 2.1.5 --- Continuous wave (CW) and pulsed wave (PW) --- p.33 / Chapter 2.1.6 --- Normal intracranial arteries through temporal and suboccipital window --- p.33 / Chapter 2.1.7 --- Normal intracranial arteries through orbital window --- p.36 / Chapter 2.1.8 --- Normal extracranial arteries --- p.36 / Chapter 2.1.9 --- TCD diagnosis for intracranial artery stenosis --- p.39 / Chapter 2.1.10 --- Example of multiple intracranial arteries stenosis --- p.39 / Chapter 2.2 --- Microembolic Signal (MES) Detection / Chapter 2.2.1 --- Device of MES monitoring --- p.41 / Chapter 2.2.2 --- Insonated artery and depth --- p.41 / Chapter 2.2.3 --- Axis length of the sample volume --- p.43 / Chapter 2.2.4 --- Fast Fourier Transform (FFT) time window overlap --- p.43 / Chapter 2.2.5 --- Distinguishing embolic signal and artifact with two-gate transducer --- p.45 / Chapter 2.2.6 --- Measurements of embolic signal and threshold --- p.47 / References --- p.45 / Chapter Chapter Three --- Prevalence and Clinical Significance of Microembolic Signal (MES) in Patients with Middle Cerebral Artery (MCA) Stenosis / Chapter 3.1 --- Abstract --- p.50 / Chapter 3.2 --- Introduction --- p.51 / Chapter 3.3 --- Methodology --- p.51 / Patients / Severity of stroke and clinical course / Diagnosis for middle cerebral artery (MCA) stenosis / Microembolic signal (MES) detection / Statistical analysis / Chapter 3.4 --- Results --- p.55 / Baseline information of patients / Prevalence of MES / Relationship between presence of MES and severity of MCA stenosis / Correlation between presence of MES and clinical course in 85 symptomatic patients / Correlation between the count of MES and clinical course in 85 symptomatic patients / Correlation between the presence of MES and further ischemic stroke / Chapter 3.5 --- Discussion --- p.63 / Prevalence of MES / Association between severity of stroke and presence or the number of MES / Predictive value of MES for further stroke / References --- p.66 / Chapter Chapter Four --- Mechanisms of Acute Cerebral Infarction in Patients with Cerebral Artery Stenosis: a Diffusion-weighted Imaging and Microemboli Monitoring study / Chapter 4.1 --- Abstract / Chapter 4.2 --- Introduction --- p.72 / Chapter 4.3 --- Methodology --- p.73 / Patients / Microembolic signal (MES) detection by transcranial Doppler (TCD) / "Magnetic resonance imaging (DWI, MRI and MRA)" / Statistical analysis / Chapter 4.4 --- Results --- p.77 / Severity of MCA stenosis on MRA and pattern of infarct on DWI / Frequency and count of MES and its relationship with multiple and borderzone infarction on DWI / Chapter 4.5 --- Discussion --- p.79 / Frequency of MES / Pattern of cerebral infarcts on DWI / Relationship between MES and multiple infarcts on DWI / References --- p.83 / Chapter Chapter Five / Chapter Chapter Five-I --- Novel Observations of the Characteristics of Real Time Genesis of Thromboembolism in Middle Cerebral Artery Stenosis Detected by Transcranial Doppler / Chapter 5.1.1 --- Abstract --- p.90 / Chapter 5.1.2 --- Introduction --- p.91 / Chapter 5.1.3 --- Methodology --- p.91 / Characteristics of patients / "MRA, DWI and conventional TCD data" / MES monitoring method and overall data / Neuroimaging and MES monitoring data in all five patients / Signal analysis in off-line / Confirmation test for the origin of MES / Chapter 5.1.4 --- Results --- p.104 / Frequency of three special phenomena / Characteristics of three special phenomena / Results of confirmation test for embolic source / Chapter 5.1.5 --- Discussion --- p.133 / Occurrence of MES with flow velocity change simultaneously / MES splatter / Bi-directional low frequency (S-velocity) vibration / Testing for source of MES detected from MCA stenosis / References --- p.139 / Chapter Chapter Five-II --- Characteristics of Microembolic Signals Detected near Its Origin from the Middle Cerebral Artery Stenosis / Chapter 5.2.1 --- Abstract --- p.143 / Chapter 5.2.2 --- Introduction --- p.144 / Chapter 5.2.3 --- Methodology --- p.144 / Patients / Microembolic signal (MES) detection / Classification of MES / Chapter 5.2.4 --- Results --- p.145 / Types of MES detected from MCA stenosis / Characteristics of three types of MES / Chapter 5.2.5 --- Discussion --- p.157 / Emboli moving from vessel wall to the center / Emboli vibration / About calculating the time delay between two channels / References --- p.160 / Chapter Chapter Five-III --- "Hemodynamic change,microembolic signal counts and use of antithrombotic treatments" / Chapter 5.3.1 --- Abstract --- p.163 / Chapter 5.3.2 --- Introduction --- p.164 / Chapter 5.3.3 --- Methodology --- p.164 / Chapter 5.3.4 --- Results / "The relationship among flow velocity, the number of MES and time since symptom onset" --- p.165 / Patient one / Patient two / Patient three / Chapter 5.3.5 --- Discussion / Association between flow velocity or MES change and different anticoagulants in acute stage / Progression of MCA stenosis after acute stage / Stability of MCA atherosclerotic stenosis / References --- p.173 / Chapter Chapter Six --- The Optimal Values of Flow Velocity on Transcranial Dopplerin Grading Severity of Middle Cerebral Artery Stenosis in Comparison With Magnetic Resonance Angiography / Chapter 6.1 --- Abstract --- p.179 / Chapter 6.2 --- Introduction --- p.180 / Chapter 6.3 --- Methodology --- p.180 / Patients / TCD examination / Grading of MCA stenosis on MRA / Statistical analysis / Chapter 6.4 --- Results --- p.182 / Detection of >50% MCA stenosis according to flow velocity / Grading severity of MCA stenosis by flow velocity / Chapter 6.5 --- Discussion --- p.186 / Reliability of TCD diagnosis for MCA stenosis / Grading MCA stenosis according to flow velocity on TCD / References / Abbreviations --- p.189 / Publications --- p.191

Foram analisados os efeitos da manobra de preensão manual (PM) na autorregulação encefálica (AE) dinâmica, através de um método não estacionário que utiliza o modelo de autorregressão de médias móveis. Doze indivíduos saudáveis foram orientados a realizar a manobra de PM durante 11 minutos com contração muscular constante e carga de 30% da força máxima. Registraram-se continuamente as medidas da velocidade do fluxo sanguíneo nas artérias cerebrais médias, pressão parcial de CO2 (PCO2) no ar expirado e pressão arterial (PA) não invasiva, durante o repouso (5 min), PM (3 min) e recuperação (3 min). A pressão crítica de fechamento (PCrF) e o produto área-resistência (PAR) foram obtidos empregando-se o método do primeiro harmônico. O índice de autorregulação encefálica (IAE) variável no tempo foi calculado através do modelo da autorregressão de médias móveis. As variáveis foram expressas em porcentagem de variação em relação aos valores obtidos no repouso (30 s previamente ao início da manobra de PM). Não houve alteração significativa da PCO2 do ar expirado durante MP. A PA aumentou continuamente durante a manobra (27% dos valores basais), enquanto que a velocidade do fluxo sanguíneo encefálico elevou-se inicialmente e alcançou um platô (15% dos valores basais). A elevação da PA aumentou o PAR, possivelmente devido à vasoconstricção arteriolar encefálica, o que refletiria a atuação do componente miogênico na regulação do fluxo sanguíneo encefálico; por outro lado, a PCrF reduziu-se, o que representa a ação do mecanismo metabólico. O IAE apresentou diminuição tanto no início quanto ao fim da manobra de PM; este achado pode estar relacionado à reação de alerta e/ou à diferença no tempo de resposta dos mecanismos envolvidos na adaptação neurovascular (mecanismos miogênico, metabólico e neurogênico). Conclui-se que o estudo da AE dinâmica com o modelo da autorregressão de médias móveis, durante a manobra de PM, pode ampliar os conhecimentos acerca das modificações hemodinâmicas encefálicas durante o exercício e elucidar aspectos ainda pouco conhecidos da resposta fisiológica do organismo / We investigated the effect of handgrip (HG) maneuver on time-varying estimates of dynamic cerebral autoregulation (CA), using the autoregressive moving average (ARMA) technique. Twelve healthy subjects were recruited to perform HG maneuver during 3 minutes with 30% of maximum contraction force. Cerebral blood flow velocity, end-tidal CO2 pressure (PETCO2), and noninvasive arterial blood pressure (ABP) were continuously recorded during baseline, HG and recovery. Critical closing pressure (CrCP), resistance areaproduct (RAP), and time-varying autoregulation index (ARI) were obtained. PETCO2 did not show significant changes during HG maneuver. Whilst ABP increased continuously during the maneuver, to reach 27% of its baseline value, CBFV raised to a plateau approximately 15% above baseline. This was sustained by a parallel increase in RAP, suggestive of myogenic vasoconstriction, and a reduction in CrCP that could be associated with metabolic vasodilation. The time-varying ARI index dropped at the beginning and end of the maneuver (p<0.005), which could be related to corresponding alert reactions or to different time constants of the myogenic, metabolic and/or neurogenic mechanisms. Changes in dynamic CA during HG suggest a complex interplay of regulatory mechanisms during static exercise that should be considered when assessing the determinants of cerebral blood flow and metabolism

Foram analisados os efeitos da manobra de preensão manual (PM) na autorregulação encefálica (AE) dinâmica, através de um método não estacionário que utiliza o modelo de autorregressão de médias móveis. Doze indivíduos saudáveis foram orientados a realizar a manobra de PM durante 11 minutos com contração muscular constante e carga de 30% da força máxima. Registraram-se continuamente as medidas da velocidade do fluxo sanguíneo nas artérias cerebrais médias, pressão parcial de CO2 (PCO2) no ar expirado e pressão arterial (PA) não invasiva, durante o repouso (5 min), PM (3 min) e recuperação (3 min). A pressão crítica de fechamento (PCrF) e o produto área-resistência (PAR) foram obtidos empregando-se o método do primeiro harmônico. O índice de autorregulação encefálica (IAE) variável no tempo foi calculado através do modelo da autorregressão de médias móveis. As variáveis foram expressas em porcentagem de variação em relação aos valores obtidos no repouso (30 s previamente ao início da manobra de PM). Não houve alteração significativa da PCO2 do ar expirado durante MP. A PA aumentou continuamente durante a manobra (27% dos valores basais), enquanto que a velocidade do fluxo sanguíneo encefálico elevou-se inicialmente e alcançou um platô (15% dos valores basais). A elevação da PA aumentou o PAR, possivelmente devido à vasoconstricção arteriolar encefálica, o que refletiria a atuação do componente miogênico na regulação do fluxo sanguíneo encefálico; por outro lado, a PCrF reduziu-se, o que representa a ação do mecanismo metabólico. O IAE apresentou diminuição tanto no início quanto ao fim da manobra de PM; este achado pode estar relacionado à reação de alerta e/ou à diferença no tempo de resposta dos mecanismos envolvidos na adaptação neurovascular (mecanismos miogênico, metabólico e neurogênico). Conclui-se que o estudo da AE dinâmica com o modelo da autorregressão de médias móveis, durante a manobra de PM, pode ampliar os conhecimentos acerca das modificações hemodinâmicas encefálicas durante o exercício e elucidar aspectos ainda pouco conhecidos da resposta fisiológica do organismo / We investigated the effect of handgrip (HG) maneuver on time-varying estimates of dynamic cerebral autoregulation (CA), using the autoregressive moving average (ARMA) technique. Twelve healthy subjects were recruited to perform HG maneuver during 3 minutes with 30% of maximum contraction force. Cerebral blood flow velocity, end-tidal CO2 pressure (PETCO2), and noninvasive arterial blood pressure (ABP) were continuously recorded during baseline, HG and recovery. Critical closing pressure (CrCP), resistance areaproduct (RAP), and time-varying autoregulation index (ARI) were obtained. PETCO2 did not show significant changes during HG maneuver. Whilst ABP increased continuously during the maneuver, to reach 27% of its baseline value, CBFV raised to a plateau approximately 15% above baseline. This was sustained by a parallel increase in RAP, suggestive of myogenic vasoconstriction, and a reduction in CrCP that could be associated with metabolic vasodilation. The time-varying ARI index dropped at the beginning and end of the maneuver (p<0.005), which could be related to corresponding alert reactions or to different time constants of the myogenic, metabolic and/or neurogenic mechanisms. Changes in dynamic CA during HG suggest a complex interplay of regulatory mechanisms during static exercise that should be considered when assessing the determinants of cerebral blood flow and metabolism

Early deterioration and long-term recurrence were common after stroke or transient ischemic attach (TIA), however, it is unclear whether they were correlated with active embolization and the consequent new cerebral infarct in acute phase. By employing TCD and diffusion weighted imaging (DWI), we studied the significance of the progression of MES and infarcts during acute phase on the clinical outcomes. We found that the disappearance of MES was correlated with better improvement on day 7 of recruitment; for the long-term outcome, occurrence of exacerbating infarct tended to predict recurrent stroke. Treatment aiming to reduce MES and prevent infarct exacerbation in acute phase may improve the prognosis after stroke. / Finally, one study was performed to assess the changes of hemodynamic parameters after stenting of severe stenosis in the MCA. We aimed to investigate whether TCD can reflect the lumen changes after revascularization and detect hyperperfusion. The findings showed that the velocity of stented MCA in most patients normalized within 24 hours after procedure, but the role of TCD in detecting restenosis in long run needed to be verified; no one suffered from hyperperfusion during the period of our study. The long-term outcomes of patients with normalized velocity versus those with persistently high velocity needed to be further studied. Apart from the velocity changes, changes of the collateral flow after intervention may also be an important part of hemodynamic changes. (Abstract shortened by UMI.) / It was suggested that anti-platelet therapy can reduce the MES, but little was known about the efficacy of low molecular weight heparin (LMWH) although in theory LMWH can reduce the red fibrin-dependent thromboemboli. As a sub-analysis of Fraxiparine in Ischemic Stroke (FISS)-tris study, our study did not show advantages of LMWH in eliminating MES compared with aspirin. / Previous studies showed the accuracy of TCD in diagnosis of middle cerebral artery (MCA) stenosis was variable and the positive predictive value (PPV) was less than 50% in a recent report. One of the important reasons was that most criteria were based on the velocity-only method, ignoring other non-velocity information. Thus, we tried to establish new diagnostic criteria by means of designing an assessment form which integrated more characteristics apart from the velocity acceleration. A composite score for each MCA was calculated according to following parameters in the form: Velocity Scale (score 0-6 for peak systolic velocities&lt;140 to &ge;300cm/s), Hemodynamic Scale (score 0-5 for focal or diffuse velocity increase; score 0-6 for differences between bilateral MCA; score 17 for damping velocity), Spectrum Scale (score 0-2 for normal spectrum, turbulence and musical murmurs). Our results showed that compared with the previously reported criteria, the score calculated from the assessment form yielded much more balanced accuracy against magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). However, the composition of the assessment form was only based on personal experience and need to be further modified. Multicenter studies with large sample size are also needed to confirm the advantages of this new method. / Second, we performed three studies to investigate the relationship between the progression of MES and the short or long-term outcome and the relationship between MES and different treatments. / Hao, Qing. / Adviser: Ka Sing Wong. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3419. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 155-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

<p>Otkrivanje embolusa u cerebralnoj cirkulaciji na egzaktan način moguće je samo upotrebom transkranijalnog doplera. Istraživanje je obuhvatilo 150 ispitanika, obolelih od akutnog ishemijskog cerebrovaskularnog događaja (ishemijskog moždanog udara i tranzitornog ishemijskog ataka) u zoni vaskularizacije a. cerebri medie (ACM), a lečenih na Klinici za neurologiju, Kliničkog centra Vojvodine. Ciljevi istraživanja su obuhvatili određivanje prevalence i frekvence MES kod bolesnika sa akutnim ishemijskim cerebrovaskularnim događajem (TIA, IMU) tokom serijskog monitoringa, utvrđivanje povezanost pojave MES u odnosu na etiologiju ishemijske epizode, procenjivanje efekata terapije (antiagregacione i antikoagulantne) na pojavu MES tokom serijskog monitoringa, i utvrđivanje prediktivnog značaja MES na dalji tok bolesti tj, rani povratni embolizam unutra tri meseca. Utvrdili smo da se mikroembolusi kao markeri aktivne embolizacije mogu registrovati primenom transkranijalnog doplera u akutnoj fazi moždanog udara u određenoj meri. U ispitivanom uzorku metodom transkranijalne detekcije kod 52 (34,7%) bolesnika je registrovana pojava cerebralnih mikroembolusa. Ovi ispitanici su činili MES (+) grupu pacijenata. Kod 98 (65,3%) bolesnika nisu registrovani ES, oni su činili MES (-) grupu pacijenata. Detekcija je vr&scaron;ena u prvih 72h od vremena nastanka IMU ili TIA. Zaključili smo da se serijskim monitoringom registruje smanjenje prevalence i frekvence embolijskih signala. Utvrdili smo da su starija životna dob, hipertenzija i dijabetes statistički značajno povezani sa pojavom mikroembolusnih signala. Najveća zastupljenost mikroembolusa registrovana je u aterotrombotičnom podtipu ishemijskog moždanog udara. Utvrđen je prediktivni značaj aterosklerotske bolesti velikih krvnih sudova na pojavu MES. Registrovana je statistički značajno če&scaron;ća pojava MES kod simptomatske karotidne stenoze, visokog stepena (70-90%), neravne i ulcerisane povr&scaron;ine plaka. Nije utvrđena statistički značajna povezanost pojave MES, kliničkih manifestacija bolesti i neuroradiolo&scaron;kog nalaza. Nije registrovan uticaj antitrombotičke terapije na pojavu mikroembolusnih signala. Zabeležena je veća stopa recidiva IMU i TIA kod bolesnika sa registrovanim cerebralnim mikroembolusima. Utvrđen je prediktivni značaj MES na pojavu recidiva IMU ali ne i prediktivni značaj na pojavu letalnog ishoda.</p> / <p>Detection of emboli in the cerebral circulation to the exact way it is possible only by using transcranial doppler. The study included 150 patients of acute ischemic cerebrovascular events (ischemic stroke and TIA) in a zone of vascularization a. cerebri media (ACM), and treated at the Clinic of Neurology, Clinical Center of Vojvodina Research objectives included the determination of the prevalence and frequency of MES in patients with acute ischemic cerebrovascular accident (TIA, IMU) during serial monitoring, establishing the link between the appearance MES in relation to the etiology of ischemic episodes, assessing the effects of therapy<br />(antiplatelet and anticoagulant) on the occurrence of MES during serial monitoring and determine the predictive value MES in the further course of the disease, ie. return early embolism within three months. We have found that microemboli as markers of active embolization can register by using transcranial Doppler in the acute phase of stroke in certain extent. In the examined sample using transcranial detection with 52 (34.7%) patients the occurrence of cerebral microemboli is registered. These respondents are accounted for MES (+) group of patients. With 98 patients (65.3%) is not registered EC, they account for MES (-) group of patients. Detection was performed during 72 hours from the time of occurrence of ischemic stroke or TIA. We concluded that serial monitoring registers decrease in prevalence and frequency of embolic signals. We found that older age, hypertension, and diabetes are significantly associated with the appearance of microembolic signals. The highest incidence of microemboli was registered in atherothrombotic ischemic stroke subtype. It is determined the predictive significance of atherosclerotic disease of large blood vessels on the occurrence of MES. More common MES is significantly registered with symptomatic carotid stenosis, greater degree (70-90%), uneven surfaces and ulcerated plaque. There was no statistically significant correlation between the occurrence of MES, clinical manifestations and neuroradiological findings. It is not registered impact of antithrombotic therapy on the incidence of microembolic signals. We are noticed thet the higher rate of recurrence of ischemic stroke and TIA patients with cerebral microemboli is registered. The predictive significance of MES in recurrence of ischemic stroke is determined, but not predictive significance of the occurrence of a lethal outcome.</p>

<p>TCD apnea test kao neinvazivna i bezbedna neuroultrasonografska metoda pruža korisne informacije o vazomotornoj reaktivnosti (VMR) u procesu indirektnog sagledavanja funkcionisanja moždane autoregulacije. Vazomotorna reaktivnosti podrazumeva sposobnost dilatacije ili konstrikcije moždanih arteriola nastale kao odgovor na određeni vazoaktivni stimulus, najče&scaron;će ugljen dioksid. Cilj ove doktorske disertacije bio je ispitivanje i analiziranje promene karotidne hemodinamike kod bolesnika sa ishemijskim moždanim udarom (IMU) ili tranzitornim ishemijskim atakom (TIA) i simptomatskom karotidnom stenozom u preoperativnom i tromesečnom postoperativnom periodu, kao i procena revaskularizacionog efekta karotidne endarterektomije (KEA).U istraživanje je uključeno 60 hospitalizovanih bolesnika koji su doživeli prvi IMU i TIA u zoni vaskularizacije arterije cerebri anterior (ACA) i arterije cerebri medije (ACM), svi sa karotidnom stenozom, ACI &ge;70%. Bolesnici su bili hospitalizovani na Klinici za neurologiju, Kliničkog Centra Vojvodine, Klinici za kardiovaskularnu hirurgiju, Instituta za kardiovaskularne bolesti Vojvodine i Klinici za vaskularnu hirurgiju, u Novom Sadu. U odnosu na kliničke manifestacije bolesni i su podeljeni u tri grupe: bolesnici sa TIA i amaurosis fugax, sa parcijalnim infarktom u zoni ACA ili ACM i sa lakunarnim infarktom. Istraživanje je analiziralo uticaj promenljivih i nepromenljivih vaskularnih faktora rizika na pojavu IMU i TIA, ali i na VMR, procenjivanu kroz indeks zadržavanja daha (Breath Holding Index, BHI) ipsilateralno i kontralateralno u odnosu na karotidnu stenozu. Analizirana je povezanost stepena karotidne stenoze sa vrednostima BHI preoperativno, povezanost BHI sa težinom kliničke slike, uticaj kolateralnog krvotoka na VMR, distribucija BHI u pojedinim tipovima IMU i TIA kao i komparacija BHI u pre i u postoperativnom periodu od 30 i 90 dana. Na osnovu sprovedenog istraživanja, do&scaron;lo se do zaključaka da je redukovana VMR preoperativna karakteristika karotidne stenoze ipsilateralno kao i karakteristika različitih tipova IMU i TIA ipsilateralno; postoji negativna korela ija izmeĐu stepena karotidne stenoze i BHI vrednosti. Nije potvrđena hipoteza da veći roj razvijenih kolateralnih puteva uslovljava očuvanu VMR; utvrđena je pozitivna korelacija između BHI vrednosti u preoperativnom i postoperativnom periodu; redukovana VMR ima negativan uticaj na težinu kliničke slike. Prepoznavanje vrednosti TCD apnea testa, koji se može koristiti kao komplementarna metoda drugim vazoaktivnim testovima u praćenju karotidne hemodinamike, od posebne je važnosti neurologu i vaskularnom hirurgu. Time bi se doprinelo daljoj evaluaciji mehanizma nastanka IMU, planiranju terapijskog pristupa i determinisanju prognoze operisanih bolesnika. Činjenica da većina neurolo&scaron;kih odeljenja poseduje TCD aparat, apnea test postaje dostupan svakom neurologu u kliničkom radu, posebno u na&scaron;im uslovima, kada se do drugih drugih, skupljih metoda, te&scaron;ko stiže ili nam ostaju nedostižne.</p> / <p>TCD apnea test, as a noninvasive and safe neuroultrasonographic method, provides useful information about vasomotor reactivity (VMR) in the indirect evaluation of cerebral autoregulation. Vasomotor reactivity is the ability of cerebral arterioles to constrict or to dilate in response to a vasoactive stimulus, mainly carbon dioxide. The aim of this doctoral thesis was to investigate and analyze changes in carotid hemodynamics in patients with ischemic stroke (IS) or transient ischemic attack (TIA) and symptomatic carotid stenosis in the preoperative and three-month postoperative period as well as the assessment of revascularisation effect of carotid endarterectomy (CEA). The study included 60 hospitalized patients who experienced a first ischemic stroke or TIA in the vasularisation area of anterior cerebral artery (ACA) and middle cerebral artery (MCA), all with carotid stenosis &ge;70% ACI. Patients were hospitalized at the Clinic of Neurology, Clinical Center of Vojvodina, Department of Cardiovascular Surgery, Institute of Cardiovascular Diseases and the Department of Vascular Surgery in Novi Sad. Considering clinical manifestations of stroke, the patients were divided into three groups: patients with TIA and amaurosis fugax, with partial infarction in area ACA or ACM and with lacunar infarct. The study analyzed the impact of variabile and unvariable vascular risk factors on the incidence of ischemic stroke and TIA, but also on VMR, evaluated through Breath Holding Index (Breath Holding Index, BHI) on the ipsilateral and contralateral side from carotid stenosis. We analysed the correlation between the degree of carotid stenosis with preoperative values of BHI, BHI correlation to the severity of clinical findings, the impact of collateral circulation to the VMR, distribution of BHI in certain types of ischemic stroke and TIA as well as comparison of BHI in the pre and postoperative period of 30 and 90 days. On the basis of this research came the conclusion that reduced VMR is characteristic of ipsilateral carotid stenosis in preoperative period as well as number of developed collateral characteristics of different types of ipsilateral ischemic stroke and TIA; there is a negative correlation between the degree of carotid stenosis and BHI values. The hypothesis that the greater pathways causes preservation of VMR was not confirmed, while the positive correlation between BHI values in the preoperative and postoperative period was established. Reduced VMR has a negative impact on the degree of clinical picture severity. Recognizing the importance of TCD apnea test method, that can be used as a complementary method to other vasoactive tests in monitoring of carotid hemodynamics, is of special importance to the neurologists and vascular surgeons. This would contribute to the further evaluation of mechanism of ischemic stroke, planning of therapeutic approach and determining the prognosis of treated patients. The fact that most of neurological department has TCD device, apnea test becomes available to every neurologist in clinical work, specially in our conditions, when other methods remain unattainable.</p>

INTRODUÇÃO. Atualmente, o tratamento da hidrocefalia é realizado principalmente através de uma Derivação ventrículo-peritoneal (DVP). Este estudo tem como objetivo descrever a aplicação da derivação ventrículosinusal retrógrada (DVSR) em pacientes com hidrocefalia após o tratamento cirúrgico de mielomeningocele. MÉTODO. Estudo prospectivo, randomizado e controlado. Foram selecionados consecutivamente 9 pacientes com hidrocefalia após correção cirúrgica de mielomeningocele de janeiro de 2010 a janeiro de 2012. Os pacientes foram submetidos à DVSR ou DVP eletiva. Cinco submetidos à DVSR e 4 à DVP, sendo seguidos por 1 ano com realização trimestral de avaliações clínicas, de imagem e aplicação do Doppler transcraniano. RESULTADOS. Os pacientes tratados com DVSR apresentaram desfechos clínicos semelhantes aos do grupo de DVP. O Doppler mostrou melhora significativa quando comparado o pré-operatório com o pós-operatório. O grupo DVSR apresentou perímetro cefálico significativamente maior que o grupo DVP. O desenvolvimento neuropsicomotor, complicações e desfechos centrados nos pacientes não diferiram entre os grupos. CONCLUSÕES. A técnica cirúrgica da derivação ventrículo-sinusal retrógrada é viável; ela é uma opção alternativa para o tratamento de hidrocefalia / INTRODUCTION. Currently, treatment of hydrocephalus is accomplished primarily through a ventricular-peritoneal shunt (VPS). This study aims to describe the application of retrograde ventricle-sinus shunt (RVSS) in patients with hydrocephalus after surgical treatment of myelomeningocele. METHOD. A prospective, randomized and controlled study. We consecutively enrolled 9 patients with hydrocephalus after surgical repair of myelomeningocele from January 2010 to January 2012. These patients underwent elective RVSS or VPS. Five underwent RVSS and 4 underwent VPS. These patients were followed for one year with quarterly clinical and image evaluations and application of transcranial Doppler. RESULTS. Patients treated with RVSS showed clinical outcomes similar to those of VPS group. Doppler showed significant improvement when comparing preoperative to the postoperative period. RVSS group showed significantly higher cephalic perimeter than VPS group. Neuropsychomotor development, complications and subjective outcomes did not differ between groups. CONCLUSIONS. Surgical technique of retrograde ventricle-sinus shunt is viable; it is an alternative option for the treatment of hydrocephalus

O presente estudo avaliou a autorregulação encefálica (ARE) em doentes com insuficiência hepática fulminante (IHF) antes e após transplante hepático. Foram avaliados 25 pacientes com diagnóstico de IHF, 17 foram avaliados antes e após o transplante hepático, sendo seis (24,0%) do sexo masculino e 19 (76,0%) feminino. A média de idade foi de 33,8 anos, que variou de 14 a 56 anos, com desvio padrão de 13,1 anos. A hemodinâmica encefálica foi avaliada pela velocidade de fluxo sanguíneo encefálico (VFSE) nas artérias cerebrais médias e artéria basilar (AB), que usou o ultrassom Doppler transcraniano (DTC), dispositivo de dois canais, com transdutores de 2 mega Hertz (MHz). A autorregulação encefálica foi mensurada pelo índice de autorregulação (IARE) estática que leva em conta os efeitos do aumento da pressão arterial média (PAM) sobre a VFSE. Para isso, promoveu-se o aumento da PAM (20 mmHg a 30 mmHg) com infusão de noradrenalina.. Ao se avaliar o IARE considerando a velocidade de fluxo sanguíneo em quatro momentos (pré-transplante, 1°, 2° e 3° dia após o transplante), observou-se que houve diferença estatística em artéria cerebral média (ACM) à direita (p=0,008), esquerda (p=0,007), máxima (p=0,005), e AB (p=0,006); assim como na análise em cada tempo do IARE, observou-se diferença estatística em ACM à direita (p=0,012), esquerda (p=0,009), máxima (p=0,006), e AB (p=0,011). A análise categórica do IARE na artéria cerebral média e basilar descreveu que a maioria dos doentes reestabeleceu a AR no 2° dia em ACM e 3° na AB (índice > 0,6), enquanto com o índice > 0,8 em ambas as artérias a ARE reestabeleceu no 2° dia. As variáveis sistêmicas como pressão parcial de CO2 e hemoglobina nos tempos da avaliação não apresentaram diferença estatística p=0,100 e p=0,093 respectivamente. Os resultados obtidos apontam para o comprometimento da ARE antes e após transplante hepático, tanto em circulação anterior como posterior, e que tende a ser reestabelecido entre 48 a 72 horas. Os achados deste estudo favorecem o manejo adequado de doentes nestas fases (antes e após transplante) e podem evitar a evolução para complicações neurológicas, como tumefação encefálica e hipertensão intracraniana, que indicam prognóstico ruim para a evolução clínica destes doentes. Estudos futuros necessitam ser realizados para que se consolide o uso da monitoração contínua com métodos não invasivos como o DTC para direcionar o manejo hemodinâmico encefálico na IHF / This study evaluated cerebral autoregulation in patients with fulminant hepatic failure (FHF) before and after liver transplantation. A total of 25 patients comprising six (24.0%) males and 19 (76.0%) females with FHF were evaluated. Seventeen patients were evaluated both before and after liver transplantation. Mean age of the patients was 33.8 years, with a range of 14-56 years and standard deviation of 13.1 years. Brain hemodynamics was assessed by cerebral blood flow velocity in the middle cerebral arteries (MCA) and basilar artery (BA) using transcranial Doppler ultrasound on a two-channel device with 2 MHz transducers. Cerebral autoregulation was measured by static cerebral autoregulation index (SCAI), which accounts for the effects of increase in mean arterial blood pressure (ABP) on cerebral blood flow velocity. An increase in ABP (20 mmHg to 30 mmHg) was induced with norepinephrine infusion. Evaluation of SCAI based on blood flow velocity (BVF) at four timepoints (pre-transplant and on 1st, 2nd and 3rd days post-transplant) revealed a statistical difference in the MCA right (p = 0.008) left (p = 0.007), maximum (p = 0.005) and the BA (p = 0.006). In addition, analysis by timepoint showed a statistical difference in MCA (p = 0.012), left (p = 0.009), maximum (p = 0.006) and in the BA (p = 0.011). Categorical analysis of autoregulation in the MCA and BA showed that most patients reestablished autoregulation in the MCA on the 2nd day post-transplant and in the BA (index > 0.6) on the 3rd day, while autoregulation was reestablished in both arteries (index > 0.8) on the 2nd day. On the assessment by timepoint, the systemic variables CO2 partial pressure and hemoglobin showed no statistically significant differences (p = 0.100 and p = 0.093, respectively). The results reveal impaired SCAI before and after liver transplantation, both in anterior and posterior circulation, with a tendency to reestablish at 48 to72 hours. The findings of this study can help improve management of patients at these stages (pre and post transplantation), preventing neurological complications such as brain swelling and intracranial hypertension, associated with poor prognosis for the clinical course. Future studies should be conducted to consolidate the use of continuous monitoring with noninvasive method (TCD), to provide more accurate information to guide brain hemodynamic management in FHF

Orientadores: Sebastião Araujo, Venancio Pereira Dantas Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T15:16:20Z (GMT). No. of bitstreams: 1 Sardinha_LuizAntoniodaCosta_M.pdf: 2011440 bytes, checksum: 851ec72bdf3a8bdfb52b9cb454b11066 (MD5) Previous issue date: 2008 / Resumo: Justificativa e Objetivo. No Brasil, o diagnóstico clínico de morte encefálica (ME) requer pelo menos um exame subsidiário para sua confirmação, e o Doppler transcraniano (DTC) tem sido aceito para documentar a parada circulatória cerebral (PCC). Assim, o principal objetivo do presente estudo é relatar nossa experiência com o uso do DTC na confirmação de ME. Método. Análise retrospectiva dos exames de DTC realizados entre janeiro/2001 e dezembro/2005 em 152 potenciais doadores de órgãos notificados à Organização de Procura de Órgãos do Hospital de Clínicas da Universidade Estadual de Campinas. O diagnóstico clínico de ME foi feito de acordo com o protocolo do Conselho Federal de Medicina (CFM). A artéria carótida interna (ACI) e as circulações arteriais cerebrais anteriores e posteriores foram examinadas. O achado de certos padrões específicos de alterações no DTC, conforme descritos em literatura, foram considerados para a confirmação de PCC. Resultados. Em 150 pacientes o DTC foi compatível com PCC no 1º exame. Em dois pacientes, o DTC mostrou fluxo sangüíneo cerebral residual, e um 2º exame realizado 12 horas mais tarde permaneceu ainda inconclusivo para a confirmação de PCC. Ambos foram descartados como doadores de órgãos, falecendo dentro de 48 horas. Conclusão. O DTC mostrou-se um excelente teste subsidiário para a confirmação do diagnóstico clínico de ME. O baixo custo e a portabilidade do equipamento, permitindo a realização do exame à beira do leito, têm permitido uma maior agilização e efetividade na procura e captação de órgãos para transplantes em nosso meio. / Abstract: Background and Objective. In Brazil, clinical diagnosis of brain death (BD) requires at least one ancillary test for its confirmation, and transcranial Doppler ultrasonography (TCD) has been accepted for determination of cerebral circulation arrest (CCA). The main objective of the present study is to report our experience with TCD to confirm BD in potential organ donors. Methods. Retrospective evaluation of TCD performed between January/2001 and December/2005 in 152 potential organ donors notified to an Organ Procurement Organization (OPO) at Campinas, São Paulo State, Brazil. Clinical determination of BD was done according to the protocol approved by the Brazilian Federal Council of Medicine. Internal carotid arteries and bilateral anterior and posterior cerebral circulation were insonated. The presence of specific TCD flow patterns, as previously described in medical literature, were considered for CCA confirmation. Results. In 150 patients TCD was compatible with CCA at the 1st examination. In two patients, TCD has shown residual cerebral blood flow. A 2nd examination was performed 12 hours later, remaining yet inconclusive for confirmation of CCA. Both patients were discarded as organ donors and had been died in 48 hours. Conclusion. TCD examination has shown to be an excellent ancillary test for BD confirmation. In our experience, equipment low cost and portability, allied to the possibility of bedside examination, avoiding patient transportation, has allowed a more agile and effective organ procurement for transplantation in our region. / Mestrado / Mestre em Cirurgia

O presente estudo avaliou a autorregulação encefálica (ARE) em doentes com insuficiência hepática fulminante (IHF) antes e após transplante hepático. Foram avaliados 25 pacientes com diagnóstico de IHF, 17 foram avaliados antes e após o transplante hepático, sendo seis (24,0%) do sexo masculino e 19 (76,0%) feminino. A média de idade foi de 33,8 anos, que variou de 14 a 56 anos, com desvio padrão de 13,1 anos. A hemodinâmica encefálica foi avaliada pela velocidade de fluxo sanguíneo encefálico (VFSE) nas artérias cerebrais médias e artéria basilar (AB), que usou o ultrassom Doppler transcraniano (DTC), dispositivo de dois canais, com transdutores de 2 mega Hertz (MHz). A autorregulação encefálica foi mensurada pelo índice de autorregulação (IARE) estática que leva em conta os efeitos do aumento da pressão arterial média (PAM) sobre a VFSE. Para isso, promoveu-se o aumento da PAM (20 mmHg a 30 mmHg) com infusão de noradrenalina.. Ao se avaliar o IARE considerando a velocidade de fluxo sanguíneo em quatro momentos (pré-transplante, 1°, 2° e 3° dia após o transplante), observou-se que houve diferença estatística em artéria cerebral média (ACM) à direita (p=0,008), esquerda (p=0,007), máxima (p=0,005), e AB (p=0,006); assim como na análise em cada tempo do IARE, observou-se diferença estatística em ACM à direita (p=0,012), esquerda (p=0,009), máxima (p=0,006), e AB (p=0,011). A análise categórica do IARE na artéria cerebral média e basilar descreveu que a maioria dos doentes reestabeleceu a AR no 2° dia em ACM e 3° na AB (índice > 0,6), enquanto com o índice > 0,8 em ambas as artérias a ARE reestabeleceu no 2° dia. As variáveis sistêmicas como pressão parcial de CO2 e hemoglobina nos tempos da avaliação não apresentaram diferença estatística p=0,100 e p=0,093 respectivamente. Os resultados obtidos apontam para o comprometimento da ARE antes e após transplante hepático, tanto em circulação anterior como posterior, e que tende a ser reestabelecido entre 48 a 72 horas. Os achados deste estudo favorecem o manejo adequado de doentes nestas fases (antes e após transplante) e podem evitar a evolução para complicações neurológicas, como tumefação encefálica e hipertensão intracraniana, que indicam prognóstico ruim para a evolução clínica destes doentes. Estudos futuros necessitam ser realizados para que se consolide o uso da monitoração contínua com métodos não invasivos como o DTC para direcionar o manejo hemodinâmico encefálico na IHF / This study evaluated cerebral autoregulation in patients with fulminant hepatic failure (FHF) before and after liver transplantation. A total of 25 patients comprising six (24.0%) males and 19 (76.0%) females with FHF were evaluated. Seventeen patients were evaluated both before and after liver transplantation. Mean age of the patients was 33.8 years, with a range of 14-56 years and standard deviation of 13.1 years. Brain hemodynamics was assessed by cerebral blood flow velocity in the middle cerebral arteries (MCA) and basilar artery (BA) using transcranial Doppler ultrasound on a two-channel device with 2 MHz transducers. Cerebral autoregulation was measured by static cerebral autoregulation index (SCAI), which accounts for the effects of increase in mean arterial blood pressure (ABP) on cerebral blood flow velocity. An increase in ABP (20 mmHg to 30 mmHg) was induced with norepinephrine infusion. Evaluation of SCAI based on blood flow velocity (BVF) at four timepoints (pre-transplant and on 1st, 2nd and 3rd days post-transplant) revealed a statistical difference in the MCA right (p = 0.008) left (p = 0.007), maximum (p = 0.005) and the BA (p = 0.006). In addition, analysis by timepoint showed a statistical difference in MCA (p = 0.012), left (p = 0.009), maximum (p = 0.006) and in the BA (p = 0.011). Categorical analysis of autoregulation in the MCA and BA showed that most patients reestablished autoregulation in the MCA on the 2nd day post-transplant and in the BA (index > 0.6) on the 3rd day, while autoregulation was reestablished in both arteries (index > 0.8) on the 2nd day. On the assessment by timepoint, the systemic variables CO2 partial pressure and hemoglobin showed no statistically significant differences (p = 0.100 and p = 0.093, respectively). The results reveal impaired SCAI before and after liver transplantation, both in anterior and posterior circulation, with a tendency to reestablish at 48 to72 hours. The findings of this study can help improve management of patients at these stages (pre and post transplantation), preventing neurological complications such as brain swelling and intracranial hypertension, associated with poor prognosis for the clinical course. Future studies should be conducted to consolidate the use of continuous monitoring with noninvasive method (TCD), to provide more accurate information to guide brain hemodynamic management in FHF