Unilateral Perfusion Research Articles

Unilateral cerebral perfusion is gaining increased interest, but more evidence is still necessary.

The history of unilateral cerebral perfusion can be traced to the early 1980s [1]; however, this protection strategy had not gained popularity until the introduction of supra-aortic cannulation techniques [2]. In connection with the cannulation of a supra-aortic artery, regardless if it is the brachio-cephalic, subclavian or carotid artery, the execution of unilateral perfusion is very simple, fast and can be performed without any interruption of cerebral perfusion [2, 3]. Since then, the efficacy of unilateral versus bilateral antegrade cerebral perfusion is being continuously discussed, and no consensus seems to be in sight because of the existing heterogeneity of the perfusion and cerebral protection strategies, which could be demonstrated in a large multicentre series published in the Journal a few years ago [4]. This makes any attempt to strive for evidence-based recommendations very difficult, if not impossible, because as stated in this multicentre report mentioned above: ‘…the problem in conducting prospective multicentre trials on aortic arch surgery lies on the credo of particular aortic surgeons who develop a strong attachment to their distinct perfusion and temperature management protocol with which they achieve good clinical outcomes and are not willing to switch their routine for clinical trials’ [4].

Lung perfusion scintigraphy to detect chronic lung allograft dysfunction after living-donor lobar lung transplantation

Because chronic lung allograft dysfunction (CLAD) develops predominantly on one side after bilateral living-donor lobar lung transplantation (LDLLT), lung perfusion scintigraphy (Q-scinti) was expected to show a perfusion shift to the contralateral unaffected lung with the development of CLAD. Our study examined the potential usefulness of Q-scinti in the diagnosis of CLAD after bilateral LDLLT. We conducted a single-center retrospective cohort study of 58 recipients of bilateral LDLLT. The unilateral shift values on Q-scinti were calculated and compared between the CLAD group (N = 27) and the non-CLAD group (N = 31) from 5 years before to 5 years after the diagnosis of CLAD. The unilateral shift values in Q-scinti were significantly higher in the CLAD group than in the non-CLAD group from 5 years before the diagnosis of CLAD to 5 years after the diagnosis (P < 0.05). The unilateral shift values in Q-scinti were significantly correlated with the percent baseline values of the forced expiratory volume in 1 s (P = 0.0037), the total lung capacity (P = 0.0028), and the forced vital capacity (P = 0.00024) at the diagnosis of CLAD. In patients developing unilateral CLAD after bilateral LDLLT, Q-scinti showed a unilateral perfusion shift to the contralateral unaffected lung. Thus, Q-scinti appears to have the potential to predict unilateral CLAD after bilateral LDLLT.

Characteristics of cerebral perfusion and diffusion associated with crossed cerebellar diaschisis after acute ischemic stroke.

We aimed to investigate the possible factors associated with the occurrence of crossed cerebellar diaschisis (CCD) at the hyperacute stage of ischemic stroke using whole-brain volume perfusion CT (VPCT) combined with magnetic resonance imaging (MRI). We retrospectively analyzed 108 patients with ischemic stroke within 6h of onset. The VPCT findings of the patients showed a unilateral perfusion deficit in the supratentorial territory. Follow-up MRI examinations were performed within 24h after onset. The effects of the supratentorial cerebral ischemia, the location distribution, the final infarct volume and the apparent diffusion coefficient (ADC) value on the occurrence and severity of CCD were analyzed. Among 108 patients with hyperacute cerebral ischemia, 62 (57.4%) demonstrated a contralateral cerebellar perfusion deficit on the VPCT maps. The occurrence of CCD was related to a reduction in cerebral blood volume (CBV) and prolongation of the mean transit time (MTT). Notably, the decrease in the ADC value in the infarct based on follow-up MRI was closely related to the occurrence and severity of CCD. The occurrence and severity of CCD are related to the degree of low supratentorial perfusion and the decrease in the ADC value of infarct focus.

Analysis of the neuronal damage severity and cognitive status in patients after operations on the aortic arch

Aim. To assess the neuronal damage severity and cognitive status in conditions of unilateral antegrade cerebral perfusion through the brachiocephalic trunk during surgical reconstruction of the thoracic aorta. Material and methods. The study included 144 patients with aneurysm and dissection of the thoracic aorta. Patients underwent reconstructive surgery under cardiopulmonary bypass, unilateral antegrade cerebral perfusion and circulatory arrest. Before and after the intervention, a cognitive status analysis was performed using the Montreal Cognitive Assessment (MoCA), Amatinu test and Schulte tables. The dynamics of neuron-specific enolase (NSE), a marker of neuronal damage, was determined perioperatively. Results. The duration of cardiopulmonary bypass was 155 [115; 201] min, cardioplegic arrest — 100 [72; 150] min, unilateral perfusion — 20 [15; 51] min,circulatory arrest — 20 [15; 30]min.Hospital mortality was 7% (10 cases). Neurological complications were noted in 12 (8%) cases. All patients in the postoperative period (within 24 hours) showed an increase in NSE compared with baseline values (3,3 μg/L and 2,07 μg/L, respectively, p=0,0003), but not exceeding the upper limit of normal (9,9 μg/l). According to the results of psychometric tests, which were carried out upon admission to the hospital and 2 weeks after the operation, there were no negative changes (MoCA test: 24 [21; 26] points — 26 [24; 27] points, p=0,00001; Schulte tables: 288 [240; 368] s — 278 [241; 328] s, p=0,01; Amatuni sample 264 [216; 297] s — 254 [221; 280] s, p=0,57). Conclusion. Based on the analysis of the perioperative dynamics of neuronspecific enolase and cognitive tests, unilateral cerebral perfusion through the brachiocephalic trunk is effective and relatively safe. This method of perfusion protection of the brain helps to minimize postoperative neurological complications during operations on the thoracic aorta.

Early Shift of Lung Perfusion to the Unilateral Lung Predicts the Development of Unilateral Chronic Lung Allograft Dysfunction after Bilateral Living-Donor Lobar Lung Transplantation

Purpose In the diagnosis of chronic lung allograft dysfunction (CLAD) after living-donor lobar lung transplantation (LDLLT), lung ventilation scintigraphy using 133 Xe has been shown to be useful. However, the supply of 133 Xe has been discontinued worldwide in 2016 and a new diagnostic tool is required for CLAD after LDLLT. Generally, because CLAD has been shown to develop predominantly on one side after bilateral LDLLT, lung perfusion scintigraphy (LPS) could show a perfusion shift to the unilateral healthy lung ( Figure 1A ). Nevertheless, the usefulness of LPS in the diagnosis of CLAD after LDLLT is unknown. Methods We conducted a single-center retrospective cohort study of 58 recipients who underwent bilateral LDLLT at Okayama University Hospital between October 1998 and June 2016. The unilateral shift values in LPS were calculated, and compared between the CLAD group (N=27) and the non-CLAD group (N=31) from 5 years before the CLAD onset to 5 years after the CLAD onset. Results The median time to the CLAD onset was 2176 days (326-4763 days). The unilateral shift values in LPS of the CLAD group were significantly higher than those of the non-CLAD group during 5 years before the CLAD onset (P Figure 1B ). An ROC analysis of the performance of the unilateral shift value in LPS as a marker of CLAD yielded an AUC of 0.79 (sensitivity=0.54 and specificity=1.00 at a unilateral shift threshold level of 8.6%). The unilateral shift values in LPS were significantly correlated with the results of the forced expiratory volume in 1 second (P = 0.036, r = - 0.322) ( Figure 1C ). Conclusion In the patients with unilateral CLAD after bilateral LDLLT, LPS showed the unilateral perfusion shift to the healthy lung even during 5 years before the CLAD onset. LPS might have a potential to diagnose unilateral CLAD early after bilateral LDLLT.

Neurologic Dysfunction after Aortic Dissection Surgery: Different Cerebral Hypothermic Antegrade Perfusion Techniques

Introduction: Neurologic dysfunction remains one of the most disabling complications of emergency aortic arch surgery. Many cerebral protection techniques are described, but their comparison has always been hampered by the wide spectrum of preoperative conditions, pathologic anatomies, complications, and surgical procedures. The aim of our study was to evaluate the incidence of early permanent neurologic injury and in-hospital mortality after emergency aortic arch surgery splitted by different antegrade cerebral perfusion techniques combined with hypothermic circulatory arrest (HCA). Methods: Between January 2005 and December 2015, 249 patients underwent emergent surgery for acute, type A aortic dissection. Of these, 112 (45%) (Mean age 63.8 ± 12.8 years, 82 males) received cerebral protection through antegrade perfusion of the supra-aortic vessels. Unilateral perfusion (UACP) was performed in 55 (49.1%) patients, while bilateral perfusion (BACP) was achieved via right axillary artery cannulation alone in 25 (22.3%) cases or with the Kazui technique in 32 (28.6%). Permanent neurologic injury was defined as the post-operative onset of focal stroke or lethal coma. Results: In-hospital mortality was 17.9% (UACP 20% vs. BACP 15.8%; p=0.56). The global rate of the early permanent neurologic injury was 12.3% (UACP 10.9% vs. BACP 15.8%; p=0.45). Conclusion: There is no evidence that BACP combined with HCA is superior to UACP combined with HCA for emergency aortic arch surgery in preventing early permanent neurologic injury and in-hospital mortality.

An integrative microfluidically supported in vitro model of an endothelial barrier combined with cortical spheroids simulates effects of neuroinflammation in neocortex development.

The development of therapeutic substances to treat diseases of the central nervous system is hampered by the tightness and selectivity of the blood-brain barrier. Moreover, testing of potential drugs is time-consuming and cost-intensive. Here, we established a new microfluidically supported, biochip-based model of the brain endothelial barrier in combination with brain cortical spheroids suitable to detect effects of neuroinflammation upon disruption of the endothelial layer in response to inflammatory signals. Unilateral perfusion of the endothelial cell layer with a cytokine mix comprising tumor necrosis factor, IL-1β, IFNγ, and lipopolysaccharide resulted in a loss of endothelial von Willebrand factor and VE-cadherin expression accompanied with an increased leakage of the endothelial layer and diminished endothelial cell viability. In addition, cytokine treatment caused a loss of neocortex differentiation markers Tbr1, Tbr2, and Pax6 in the cortical spheroids concomitant with reduced cell viability and spheroid integrity. From these observations, we conclude that our endothelial barrier/cortex model is suitable to specifically reflect cytokine-induced effects on barrier integrity and to uncover damage and impairment of cortical tissue development and viability. With all its limitations, the model represents a novel tool to study cross-communication between the brain endothelial barrier and underlying cortical tissue that can be utilized for toxicity and drug screening studies focusing on inflammation and neocortex formation.

大動脈弁手術時の Compromised Aorta に対する片側脳分離体外循環停止法

［背景］大動脈弁狭窄症では，上行大動脈に動脈硬化性病変を合併していることがあり，このような症例では，送血管刺入，大動脈遮断に伴う粥腫の飛散による脳梗塞を合併する危険がある．今回われわれは，片側脳分離体外循環併用循環停止下に大動脈を横切し病変の除去を行った後，上行大動脈を遮断し大動脈弁置換を行う方法を考案した．［対象・方法］2006年1月から2014年3月までに施行した大動脈弁置換術144例を対象とした．循環停止を要する大動脈瘤合併手術および感染性心内膜炎，緊急症例は除外した．上行大動脈に動脈硬化性病変を合併する症例に対する片側脳分離体外循環併用循環停止症例は5例（Compromised Aorta群：CA群），通常の上行大動脈送血および遮断を行った症例は139例（Control群）であった．CA群では右腋窩動脈および大腿動脈送血で体外循環を確立し，34度の軽度低体温循環停止下に腕頭動脈を遮断し，右腋窩動脈送血による片側脳分離体外循環を行う．脳分離の送血量は脳内酸素分圧モニター（NIRO 200NX, Hamamatsu Photonics K. K., Shizuoka, Japan）を用い調整した．短時間の循環停止下に上行大動脈を離断し，内膜病変を除去した後上行大動脈を遮断した．［結果］CA群の循環停止時間は平均3分47秒（3分0秒から5分28秒），左側の脳内酸素分圧モニターの最低値は平均52.0%（45～58%）であった．CA群5例では入院死亡，脳合併症は認めなかった（95%信頼区間（confidence interval : CI）：0.000～0.522）．Control群では死亡3例（2.2%, 95%CI : 0.003～0.046, p＝0.899），脳梗塞2例（1.4%, p＝0.932），一過性脳虚血4例（2.9%, p＝0.867）を認めた．脳梗塞，一過性脳虚血を合算した脳合併症は6例（4.3%, 95%CI : 0.009～0.077, p＝0.806）であった．また，それぞれの手術時間345.8±71.8分：333.6分±85.4（p＝0.754），人工心肺時間196.4±63.6分：199.2±50.0分（p＝0.902），大動脈遮断時間132.0±44.1分：124.8±36.3分（p＝0.666）は同等であった．［結語］石灰化およびsoft plaqueを伴うCompromised Aorta症例における短時間の片側脳分離体外循環法は，大動脈弁置換術の補助手段として有用な可能性がある．

Disinhibition reduces extracellular glutamine and elevates extracellular glutamate in rat hippocampus in vivo

Disinhibition was induced in the hippocampal CA1/CA3 region of normal adult rats by unilateral perfusion of the GABA(A)R antagonist, 4-[6-imino-3-(4-methoxyphenyl)pyridazin-1-yl] butanoic acid hydrobromide (gabazine), or a GABA(B)R antagonist, p-(3-aminopropyl)-p-diethoxymethyl-phosphinic acid (CGP 35348), through a microdialysis probe. Effects of disinhibition on EEG recordings and the concentrations of extracellular glutamate (GLU(ECF)), the major excitatory neurotransmitter, and of extracellular glutamine (GLN(ECF)), its precursor, were examined bilaterally in freely behaving rats. Unilateral perfusion of 10 μM gabazine in artificial CSF of normal electrolyte composition for 34 min induced epileptiform discharges which represent synchronized glutamatergic population bursts, not only in the gabazine-perfused ipsilateral hippocampus, but also in the aCSF-perfused contralateral hippocampus. The concentration of GLU(ECF) remained unchanged, but the concentration of its precursor, GLN(ECF), decreased to 73 ± 4% (n = 5) of the baseline during frequent epileptiform discharges, not only in the ipsilateral, but also in the contralateral hippocampus, where the change can be attributed to recurrent epileptiform discharges per se, with recovery to 95% of baseline when epileptiform discharges diminished. The blockade of GABA(B)R, by CGP 35348 perfusion in the ipsilateral hippocampus for 30 min, induced bilateral Na(+) spikes in extracellular recording. These can reasonably be attributed to somatic and dendritic action potentials and are indicative of synchronized excitatory activity. This disinhibition induced, in both hippocampi, (a) transient 1.6-2.4-fold elevation of GLU(ECF) which correlated with the number of Na(+) spike cluster events and (b) concomitant reduction of GLN(ECF) to ∼ 70%. Intracellular GLN concentration was measured in the hippocampal CA1/CA3 region sampled by microdialysis in separate groups of rats by snap-freezing the brain after 25 min of gabazine perfusion or 20 min of CGP perfusion when extracellular GLN (GLN(ECF)) was 60-70% of the pre-perfusion level. These intracellular GLN concentrations in the disinhibited hippocampi showed no statistically significant difference from the untreated control. This result strongly suggests that the observed decrease of GLN(ECF) is not due to reduced glutamine synthesis or decrease in the rate of efflux of GLN to ECF. This strengthens the likelihood that reduced GLN(ECF) reflects increased GLN uptake into neurons to sustain enhanced GLU flux during excitatory population bursts in disinhibited hippocampus. The results are consistent with the emerging concept that neuronal uptake of GLN(ECF) plays a major role in sustaining epileptiform activities in the kainate-induced model of temporal-lobe epilepsy.

Abstract 307: Selective Brain Perfusion in Addition to Emergency Cardiopulmonary Bypass Resuscitation After Prolonged Asphyxial Cardiac Arrest: Feasibility Studies in a Novel Rodent Model

Brief Objectives: Poor neurological recovery is the major limiting factor in the use of emergency cardiopulmonary bypass (ECPB) in cases of refractory cardiac arrest. To better control cerebral perfusion we developed a novel rodent model of selective brain perfusion (SBP) in addition to ECPB resuscitation. We conducted pilot studies on feasibility of this unique approach Methods Male: Sprague-Dawley rats (450-550 gm) were instrumented for ECPB with venous and arterial cannulation. To provide SBP, we additionally cannulated the right common carotid artery (RCCA) and confirmed SBP flow with a Transonic flow probe. First feasibility studies were performed to demonstrate bilateral cerebral flow from unilateral perfusion, and to ascertain tolerability of surgical procedure. To test gross survival effects of SBP in the setting of lethal cardiac arrest, three groups of rats underwent 15 min of asphyxial cardiac arrest followed by resuscitation with 30-min ECPB using 3 different strategies: normothermia with SBP (NT w/ SBP, N=3), hypothermia with SBP (HT w/ SBP, N=3), and hypothermia without SBP (HT w/o SBP, N=3). After: ECPB, rats were weaned off ECPB, wounds were closed, and 4-h mechanical ventilation and IV fluids were provided. Rats were then extubated and checked for neurological score (NS: 0-12), development of gross seizures, and the length of time of survival after extubation until death. Results: To access feasibility, we injected blue dye into the RCCA and we confirmed that single RCCA perfusion could perfuse the whole brain. Sham studies with rats (3) were conducted with full SBP and ECPR instrumentation for 30-min, then the RCCA was ligated, which confirmed that all rats survived without neurological deficits or limb injury for 3 days. In the pilot survival studies, the longest survival after extubation was observed in HT w/ SBP animal (7.0h±3.0), in contrast to both HT w/o SBP (1.1h±0.4) and HT w/o SBP (2.3h±0.9 ). Similar trends for improved neuro score and fewer seizure were observed for the HT w/ SBP animals. Conclusion: Our pilot study showed the feasibility of using brain selective perfusion in a rodent model of highly lethal cardiac arrest. SBP plus hypothermic ECPB trended toward improved survival and neurological outcome and warrants further study.

Unilateral versus bilateral antegrade cerebral perfusion in elective aortic arch surgery

Unilateral versus bilateral antegrade cerebral perfusion in elective aortic arch surgery

Editorial Comment: Uni- or bilateral antegrade cerebral perfusion: that is the question!

Editorial Comment: Uni- or bilateral antegrade cerebral perfusion: that is the question!

NMDA Receptors Control Cue-Outcome Selectivity and Plasticity of Orbitofrontal Firing Patterns during Associative Stimulus-Reward Learning

Neural activity in orbitofrontal cortex has been linked to flexible representations of stimulus-outcome associations. Such value representations are known to emerge with learning, but the neural mechanisms supporting this phenomenon are not well understood. Here, we provide evidence for a causal role for NMDA receptors (NMDARs) in mediating spike pattern discriminability, neural plasticity, and rhythmic synchronization in relation to evaluative stimulus processing and decision making. Using tetrodes, single-unit spike trains and local field potentials were recorded during local, unilateral perfusion of an NMDAR blocker in rat OFC. In the absence of behavioral effects, NMDAR blockade severely hampered outcome-selective spike pattern formation to olfactory cues, relative to control perfusions. Moreover, NMDAR blockade shifted local rhythmicsynchronization to higher frequencies and degradedits linkage to stimulus-outcome selective coding.These results demonstrate the importance of NMDARs for cue-outcome associative coding in OFC during learning and illustrate how NMDAR blockade disrupts network dynamics.

Lost Unilateral Capillary Perfusion During Nonpulsatile Pulmonary Circulation: Successful Recovery by Oral Sildenafil

Good status of pulmonary perfusion is essential for a successful outcome after the Fontan procedure. Increased pulmonary pressure and vascular resistance, small size of the pulmonary arteries, and significant branch stenoses reflect some of the main problems causing failing Fontan circulation. Here we report a child who underwent a staged Fontan procedure with subsequent subtotal loss of the left-sided pulmonary perfusion, although branch stenosis was successfully treated by stent implantation. Oral sildenafil caused restoration of the capillary vascular bed, improved left-sided lung perfusion, and resulted in significant clinical benefit.

Importance of inter-hemispheric prefrontal connection in the effects of non-competitive NMDA receptor antagonists

Previous studies have shown that systemic, but not unilateral intra-prefrontal cortex administration of non-competitive NMDA antagonists, increased prefrontal activity, the cortical efflux of serotonin, and induced stereotypies. In this work we used in-vivo microdialysis and immunohistochemistry to test the hypothesis as to whether MK-801 and ketamine need to act on both prefrontal cortices to reproduce these neurochemical and behavioural changes. Dialysis probes were implanted in the medial prefrontal cortex, and extracellular serotonin as well as behavioural stereotypies was measured after systemic administration of MK-801 and ketamine (1 mg/kg and 25 mg/kg, respectively), and unilateral and bilateral perfusion of both drugs (300 μm and 3 mm, respectively). Additionally, the prefrontal (glutamatergic) level of activity was measured using c-Fos immunohistochemistry. Systemic and bilateral (but not unilateral) prefrontal administration of MK-801 and ketamine increased serotonin efflux whereas only systemic administration of both drugs produced hyperlocomotion and stereotypies. The unilateral perfusion of 1 μm tetrodotoxin in the medial prefrontal cortex reduced increases of serotonin in both hemispheres, the expression of c-Fos in the contralateral side, and stereotypy scores after systemic NMDA antagonists. Our results support the hypothesis that a bilateral impairment of cortical inhibition in the medial prefrontal cortex is needed for non-competitive NMDA antagonists to induce the state of pyramidal cell hyperactivity and concurrent efflux of serotonin. Furthermore, hyperlocomotion and stereotypies produced by MK-801 and ketamine do not appear to result from changes in the activity of prefrontal cortex although this structure exerts some control over these behaviours.

Adequacy of brain and spinal blood supply with antegrade cerebral perfusion in a rat model

The purpose of this study was to examine whether different techniques used for antegrade cerebral perfusion could account for variation in the perfusion adequacy of the brain and spinal cord. Selected vessels were ligated in 30 rats, recreating a selection of approaches used in aortic arch surgery for patients undergoing circulatory arrest with antegrade cerebral perfusion. Filling of spinal and cerebral vessels was mapped after cannulation and perfusion with E20, gelatin/India ink, or buffered saline/India ink. Three clinical approaches were replicated: unilateral perfusion, bilateral perfusion, and bilateral perfusion with additional left subclavian artery perfusion. Filling of the spinal arteries via the common carotid arteries or the subclavian arteries alone was examined. Penetration of the marker was analyzed histologically. The control experiments achieved maximal arterial filling of both brain and spinal cord at gross and microscopic levels. Unilateral and bilateral antegrade cerebral perfusion provided comprehensive arterial filling of all cerebral vessels with all vascular markers. In contrast, only bilateral antegrade cerebral perfusion provided complete spinal cord perfusion with all markers. Unilateral antegrade cerebral perfusion with a viscous marker resulted in significantly reduced spinal cord arterial filling. Examination of the relative importance of either both common carotid arteries alone or both subclavian arteries alone, in terms of their adequacy of subsequent arterial filling of the spinal cord, showed severe impairment of spinal cord perfusion with either technique. Thus perfusion of both common carotid arteries resulted in only the proximal 30% of the spinal cord arteries being filled, whereas perfusion of both subclavian arteries resulted in only the proximal 40% of the spinal cord arteries being filled. Approaches to antegrade cerebral perfusion using the brachiocephalic and left common carotid arteries together gave good perfusion of both the brain and the spinal cord. Brachiocephalic perfusion alone gave good cerebral perfusion but showed some significant limitation in spinal cord perfusion with one vascular marker. Complete spinal cord perfusion with all markers under conditions of antegrade cerebral perfusion required some contribution from both the carotid system and the subclavian system together. Selected perfusion of either system alone was very inadequate for spinal cord perfusion.

Tc99m-ECD brain SPECT in patients with Moyamoya disease: A reflection of cerebral perfusion status at tissue level in the disease process

Background:Moyamoya disease is a rare, progressive cerebrovascular disorder caused by intracranial stenosis of the circle of Willis, resulting in successive ischemic events. Computed tomography (CT) and magnetic resonance imaging (MRI) play a major role in diagnosis.Objective:The aim of the study was to describe the spectrum of findings on brain SPECT in patients with Moyamoya disease and to compare the findings with other investigations.Materials and Methods:Tc99m-ECD SPECT scans of seventeen patients (7 children and 10 adults) were analysed to study the brain perfusion.Results:Features of Moyamoya disease were detected on DSA in 11 patients, CTA in one, MR angiography in one patient. Brain perfusion SPECT analysis showed unilateral perfusion defects in 11 patients, normal perfusion in 2 and bilateral defects in 4 patients. No perfusion defects despite bilateral vascular changes were noted in one patient. Cerebral infarcts were detected on MRI unilaterally in three subjects while multiple infarcts were identified in one. Tc99m-ECD Brain SPECT showed perfusion defects that were more extensive compared to those detected on MRI. Post acetazolamide studies for assessment of cerebrovascular reserve were done in three patients. Two of them showed good cerebrovascular reserve (>1). Follow-up studies post-surgical procedures (Myo-dura synangiosis) done in two patients showed partial resolution of perfusion defects in the involved areas.Conclusion:Brain perfusion scintigraphy is an important adjunct in evaluation of patients with Moyamoya disease yielding information about the direct end results of the pathology in the vessels and also prognostic information.

Antegrade cerebral protection in thoracic aortic surgery: lessons from the past decade☆

Prolonged deep hypothermic circulatory arrest (DHCA) adversely affects outcome and quality of life in thoracic aortic surgery. Several techniques of antegrade cerebral perfusion are routinely used: bilateral selective antegrade cerebral protection (SACP) by introducing catheters in the innominate and left carotid artery, unilateral perfusion through the right axillary antegrade cerebral perfusion (RAACP) or a combination of right axillary perfusion with an additional catheter in the left carotid artery (RAACCP), resulting also in bilateral perfusion. The aim of the present study was to analyse the impact of the different approaches on the quality of life (QoL). The data of 292 patients who underwent surgery of the thoracic aorta using DHCA at our hospital between January 2004 and December 2007 have been analysed and a follow-up was performed focussing on QoL, assessed with the Short Form-36 Health Survey Questionnaire (SF-36). Results were analysed according to the type of cerebral perfusion and the duration of DHCA. Patients' characteristics were similar in all groups. Of the total, 3.4% patients underwent DHCA (average 8.3+/-6.4 min) without ACP, 45.9% underwent SACP (average DHCA of 15.6+/-7.1 min), 40.4% had RAACP (average DHCA of 28.1+/-11.6 min) and 9.4% bilateral perfusion (RAACCP) (average DHCA of 43.1+/-16.7 min). The average follow-up was 23.2+/-15.1 months. QoL was preserved in all groups. For DHCA above 40 min, bilateral ACP provides superior midterm QoL than unilateral RAACP (average SF-36 95.1+/-44.4 vs 87.6+/-31.3; p=0.072). When midterm QoL is assessed, bilateral SACP provides the best cerebral protection for prolonged DHCA (>40 min).

Is unilateral antegrade cerebral perfusion equivalent to bilateral cerebral perfusion for patients undergoing aortic arch surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether unilateral antegrade cerebral perfusion is equivalent to bilateral cerebral plegia for cerebral protection during aortic arch surgery. Altogether 233 papers were found using the reported search, of which 17 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. These papers documented antegrade selective cerebral perfusion in a total of 3548 patients: bilateral cerebral perfusion in 2949 patients and unilateral perfusion in 599 patients. Both methods of cerebral perfusion resulted in neurological injury rates of <5%, but the period of antegrade cerebral perfusion allowed by bilateral perfusion was significantly higher. While unilateral perfusion allowed around 30-50 min, bilateral perfusion allowed 86 to over 164 min of ASCP with an acceptably low CVA rate. Therefore, we conclude that while both methods are acceptable, once the ASCP time is expected to rise over 40-50 min, bilateral cerebral perfusion is the technique that is best documented to be safe.

Effects of serotonin on perifornical‐lateral hypothalamic area neurons in rat

The hypocretin (HCRT) system of the perifornical-lateral hypothalamic area (PF-LHA) has been implicated in the facilitation of behavioral arousal. HCRT neurons receive serotonergic afferents from the dorsal raphe nucleus. Although in-vitro pharmacological studies suggest that serotonin (5-HT) inhibits HCRT neurons, the in-vivo effects of 5-HT on HCRT neurons in the PF-LHA and associated behavioral changes have not been described. We examined the effects of 5-HT delivered locally into the PF-LHA using reverse microdialysis on its neuronal activity and the consequent sleep-wake changes in rats. First, we quantified Fos expression (Fos-IR) in HCRT and other PF-LHA neurons following unilateral 5-HT perfusion in awake rats. Second, we determined the transient effects of 5-HT perfusion on the extracellular activity of the PF-LHA neurons recorded via microwires placed adjacent to the microdialysis probe. Third, we examined the effects of 5-HT perfusion into the PF-LHA on the sleep-wake profiles of the rats during the lights-off period. Unilateral perfusion of 5-HT into the PF-LHA in awake rats dose-dependently decreased the number of HCRT neurons exhibiting Fos-IR. 5-HT also inhibited the discharge activity of four of five responsive wake-related, putative HCRT neurons. However, unilateral perfusion of 5-HT into the PF-LHA did not produce significant behavioral changes during the 2-h recording period. These results confirm the in-vitro findings that 5-HT exerts inhibitory influences on HCRT neurons but further suggest that the inactivation of a limited number of HCRT neurons by unilateral 5-HT microdialysis may not be sufficient to induce behavioral changes.