Transcranial Doppler Research Articles

Evaluation of cerebral perfusion heterogeneity by the electrical impedance tomography

PurposeThe purpose of this study was to evaluate the ability of global inhomogeneity index (GI) and left-right asymmetry index (AI) based on electrical impedance tomography (EIT) to be used in assessing cerebral perfusion heterogeneity. The diagnostic value of these two indices in identifying abnormalities in the degree of cerebral perfusion heterogeneity was also explored.MethodsIn this study, Transcranial Doppler (TCD) was used as a control, and unilateral carotid artery was compressed to change the degree of heterogeneity of cerebral perfusion in 15 healthy volunteers. The control group consisted of an additional 15 volunteers without any intervention. EIT perfusion images were obtained by calculating the impedance difference between at the beginning and end of cerebral vasodilation. Subsequently, GI and AI were calculated based on the pixel values of intracranial regions.ResultsThe GI and AI values in the non-carotid artery compression (NCAC) group were significantly lower than those in the unilateral carotid artery compression (UCAC) group (P < 0.001), whereas there was no significant difference between the left carotid artery compression (LCAC) and right carotid artery compression (RCAC) groups. ROC analysis showed that the area under the curve (AUC), specificity and sensitivity of GI in distinguishing between NCAC and UCAC were 0.94, 0.90 and 0.87, respectively. The AUC, specificity and sensitivity of AI in distinguishing between NCAC and UCAC were 0.86, 0.87 and 0.73, respectively.ConclusionThe results demonstrated that the GI and AI effectively quantify the distribution of intracranial perfusion, demonstrating excellent validity and interindividual comparability, and the ability to detect abnormal cerebral perfusion heterogeneity.

Correlation between antihypertensive drugs and cerebral hemodynamic parameters: insights from observational findings using transcranial Doppler

AbstractBackgroundAntihypertensives (AHD) can influence cerebral autoregulation (CA) and attenuate hypertrophic concentric remodelling of arterioles. The aim of this study was to examine the associations between AHD, CA and structural and functional properties of cerebral arteries.MethodsIn this observational, cross‐sectional study 115 volunteers were divided in group 1 (non‐hypertensive) [n = 30]; group 2 (hypertensive with systolic blood pressure [SBP] < 140 and diastolic blood pressure [DBP] < 90 mmHg) [n = 54]; group 3 (hypertensive with SBP ≥ 140 or DBP ≥ 90 mmHg) [n = 31] and simultaneous measurements of systemic blood pressure (BP) and middle cerebral artery blood flow velocity (CBFV) were obtained from digital plethysmography and transcranial Doppler. Beat‐to‐beat, critical closing pressure (CrCP), resistance‐area product (RAP) and autoregulation index (ARI) values were extracted by linear regression analysis of instantaneous BP and CBFV waveforms using computerised analysis. Pulsatility index (PI) was calculated and CO2 reactivity was assessed by the breath‐holding test.ResultsDespite their higher RAP (1.7 [±0.7], p < 0.001) compared to groups 1 and 2, uncontrolled hypertensive using diuretics (p = 0.047) and α2‐agonists (p = 0.009) had significantly lower PI. Impaired CO2 reactivity was common between the two hypertensive groups (p = 0.008), however ARI, CrCP and CBFV did not differ between them and non‐hypertensive individuals and also did not correlate with any AHD used.ConclusionsUnlike the RAP, PI does not seem to reflect the real cerebrovascular resistence resulting from chronic arterial remodelling. Despite impaired CO2 reactivity, hypertensive have arterial tonus and CA comparable to non‐hypertensive. Experimental studies involving an untreated hypertensive control group are required to robustly make definitive conclusions about these questions.

Variability of day-to-day pulsatility index change in children with cerebral malaria

IntroductionCerebral malaria (CM) is a devastating disease and better understanding of etiologies of the resulting neurologic injury is needed. The purpose of this study is to describe the day-to-day (DTD) pulsatility index (PI) change measured by transcranial Doppler ultrasound (TCD), a novel measure of cerebral and vascular changes, in children with CM.MethodsA retrospective analysis of 122 children in sub-Saharan Africa with CM and 3 or more sequential TCD measurements was performed. Variability of DTD PI change was calculated as a measure of changes in vasculature overtime. Neurologic outcome was determined by the Pediatric Cerebral Performance Category (PCPC) score, a measure of neurologic function.ResultsOf the 122 participants, 77.9% had a good neurologic outcome (no neurologic sequelae), and 22.1% had a poor outcome (neurologic sequelae or died). Patients who had a poor neurologic outcome had higher levels of variability of DTD PI change in the right middle cerebral artery (MCA) (0.14 ± 0.21) and left MCA (0.17 ± 0.41) compared to those who had a good neurologic outcome (0.1 ± 0.1 and 0.11 ± 0.19, respectively). A higher variability of both left and right MCA DTD PI change was also associated with higher brain volume assessed through neuroimaging.DiscussionVariability of DTD PI change may provide early prognostic information regarding PCPC outcomes and brain volume changes seen in CM patients. Expanded research on pathophysiologic contributors to variability of DTD PI changes in children with CM is warranted.

The Influence of Tobacco Smoking Intensity on Hemodynamic Parameters: A Functional Transcranial Doppler Study on Vascular Reserve in Chronic Smokers

The Influence of Tobacco Smoking Intensity on Hemodynamic Parameters: A Functional Transcranial Doppler Study on Vascular Reserve in Chronic Smokers

Cerebral Overperfusion Despite Reduced Cortical Metabolism Is Associated with Postoperative Delirium in Cardiac Surgery Patients: A Prospective Observational Study

Background: Decreased cerebral oximetry (rSO2) in cardiac surgery is associated with postoperative delirium (POD). However, interventions optimizing intraoperative rSO2 are inconclusive. Methods: In this prospective observational cohort study, the relationship between rSO2, middle cerebral artery blood flow velocity (MCAV), and processed EEG was assessed in cardiac surgery patients with and without POD. MCAV was continuously recorded by transcranial Doppler sonography (TCD), together with continuous rSO2 and bispectral index (BIS) monitoring. Cardiopulmonary bypass (CPB) flow rate was adjusted according to body surface area. The cohort was divided into the POD and control groups, according to the postoperative results of the confusion assessment method (CAM/CAM-ICU), the 4A’s test (4AT), and the Delirium Observation Scale (DOS). A mixed model analysis was performed for intraoperative raw data. The cerebral autoregulation index was calculated from TCD, rSO2, and arterial pressure values. Differences in impaired autoregulation were compared using the Mann–Whitney U test. Results: A total of 41 patients were included in this study. A total of 13 patients (36.11%) developed postoperative delirium. There were no significant differences in the baseline characteristics of patients with or without POD. Patients with POD had lower BIS values during CPB (adjusted mean difference −4.449 (95% CI [−7.978, −0.925])). RSO2 was not significantly reduced in POD, (adjusted mean difference: −5.320, 95% CI [−11.508, 0.874]). In contrast, MCAV was significantly increased in POD (10.655, 95% CI [0.491, 20.819]). The duration of cerebral autoregulation impairment did not differ significantly for TCD and cerebral oximetry-derived indices (p = 0.4528, p = 0.2715, respectively). Conclusions: Our results suggest that disturbed cerebral metabolism reflects a vulnerable brain which may be more susceptible to overperfusion during CPB, which can be seen in increased MCAV values. These phenomena occur irrespectively of cerebral autoregulation.

Autoregulatory dysfunction in adult Moyamoya disease with cerebral hyperperfusion syndrome after bypass surgery

Cerebral hyperperfusion syndrome (CHS) is a serious complication after bypass surgery in Moyamoya disease (MMD), with autoregulatory dysfunction being a major pathogenesis. This study investigated the change of perioperative autoregulation and preoperative prognostic potentials in MMD with postoperative CHS. Among 26 hemispheres in 24 patients with adult MMD undergoing combined bypass, 13 hemispheres experienced postoperative CHS. Arterial blood pressure and cerebral blood flow velocity were perioperatively measured with transcranial Doppler ultrasound during resting and the Valsalva maneuver (VM). Autoregulation profiles were discovered in both the CHS and non-CHS groups using mean flow index (Mxa), VM Autoregulatory Index (VMAI), and a new metric termed VM Overshooting Index (VMOI). The CHS group had inferior autoregulation than the non-CHS group as indicated by VMOI on preoperative day 1 and postoperative 3rd day. Deteriorated autoregulation was observed via Mxa in the CHS group than in the non-CHS group on the postoperative 3rd and discharge days. Postoperative longitudinal autoregulation recovery in the CHS group was found in a logistic regression model with diminished group differences over the time course. This work represents a step forward in utilizing autoregulation indices derived from physiological signals, to predict the postoperative CHS in adult MMD.

A computational method to predict cerebral perfusion flow after endovascular treatment based on invasive pressure and resistance

Background and objectivePredicting post-operative flow is essential for assessing the risk of adverse events in cerebrovascular stenosis patients following endovascular treatment (EVT). This study aimed to evaluate the accuracy of the CFD simulation model in predicting post-operative velocity, flow and pressure distal to a stenosis, based on cerebrovascular microcirculatory resistance. MethodsThe patient-specific models of the extracranial and intracranial arteries were reconstructed. The cerebrovascular microcirculatory resistance was applied to estimate post-operative blood velocity and flow rates. Pearson correlation and Bland-Altman analyses were used to evaluate the correlation and agreement between CFD calculations and transcranial Doppler (TCD) measurements. ResultsThere was a strong correlation between CFD- and TCD-based mean velocities (r=0.7733; P=0.0002), with volume flow measured by both methods also showing robust correlation (r=0.8621; P<0.0001). Additionally, agreement was found between mean velocities determined by CFD simulation and those estimated by TCD (P=0.2446, mean difference −4.2089; limits of agreement -11.5764 to 3.1586). However, agreement between volume flow from CFD simulations and TCD was less consistent (P=0.0387, mean difference -0.3272, limits of agreement -0.9276 to 0.2731). ConclusionsThe computational method used in this study enables the prediction of hemodynamic changes and offers valuable support in tailoring treatment strategies for cerebrovascular stenosis lesions.

Middle cerebral artery blood velocity and end-tidal carbon dioxide responses to moderate intensity cycling in children, adolescents, and adults.

This study investigated the middle cerebral artery blood velocity (MCAv) response to constant work-rate moderate-intensity cycling exercise in 21 children (9.3 ± 0.8 yr), 17 adolescents (12.3 ± 0.4 yr), and 20 young adults (23.6 ± 2.4 yr). Participants completed an incremental ramp test to exhaustion on a cycle ergometer to determine maximal oxygen uptake and gas exchange threshold (GET) before completing three 6-min transitions at a moderate intensity (90% GET) on separate visits. On each visit, bilateral MCAv was measured by transcranial Doppler ultrasonography and breath-by-breath end-tidal carbon dioxide ([Formula: see text]) via a metabolic cart. Data were ensemble-averaged for each participant and analyzed using a monoexponential model. Absolute MCAv was significantly higher throughout exercise in children and adolescents compared with adults (P < 0.001). Children had a significantly lower relative increase in MCAv from baseline (∼12%) compared with adolescents (∼20%) and adults (∼18%, P < 0.040). All adolescents and adults had a monoexponential rise in MCAv and [Formula: see text], but this was observed in only eight children. Children and adolescents had a significantly faster MCAv time constant (τ, 12 ± 6 and 14 ± 8 s, respectively) compared with adults (27 ± 9 s, P < 0.001). MCAv τ was positively associated with faster [Formula: see text] τ in adolescents (r = 0.70, P = 0.002) but not in children (r = -0.20, P = 0.640). Time- and amplitude-based response parameters of MCAv kinetics were significantly associated with [Formula: see text] kinetics in adults (r = 0.50-0.74, P ≤ 0.025), but not in children (r = -0.19 to -0.48, P > 0.227). These findings suggest that the transition from childhood to adulthood impacts the MCAv response to exercise and the relationships between [Formula: see text] and MCAv kinetics during exercise.NEW & NOTEWORTHY This is the first study to find that children have smaller increases in Δ%MCAv (∼12%) during moderate-intensity exercise compared with adolescents and adults (∼18%-20%). Furthermore, MCAv kinetics were significantly faster in children and adolescents, compared with adults. MCAv kinetic responses were significantly and positively associated with [Formula: see text] kinetics in adults, but not in children. These novel data also suggest that the regulatory role of [Formula: see text] on MCAv during exercise begins to strengthen during adolescence.

Vasospasm in Pediatric Subarachnoid Hemorrhage.

Cerebral vasospasm (CV) is a common severe complication of subarachnoid hemorrhage (SAH), a severe type of intracranial bleeding that is uncommon in children. The purpose of this article is to review the current literature regarding this potentially devastating complication. CV may be asymptomatic and is less common in children compared to adults. Several molecular phenomena, including inflammatory ones, contribute to its pathophysiology. Better collateral circulation and higher cerebral blood flow are protective factors in children. When clinically apparent, CV may manifest as a change in the child's neurologic status or vital signs. CV can be diagnosed using brain vessel imaging, such as computed tomography angiography, magnetic resonance angiography, digital subtraction angiography, transcranial Doppler ultrasonography, and computed tomography perfusion. A reduction of < 50% in the artery's caliber confirms the diagnosis. Besides general supportive measures and causative treatment of SAH, CV management options include the administration of calcium channel blockers and neurointerventional approaches, such as intra-arterial vasodilators and balloon angioplasty. Long-term outcomes in children are usually favorable.

Quantifying neurovascular coupling through a concurrent assessment of arterial, capillary, and neuronal activation in humans: A multimodal EEG-fNIRS-TCD investigation

BackgroundThis study explored a novel multimodal neuroimaging approach to assess neurovascular coupling (NVC) in humans using electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and transcranial Doppler ultrasound (TCD). MethodsFifteen participants (nine females; age 19–32) completed concurrent EEG-fNIRS-TCD imaging during motor (finger tapping) and visual (“Where's Waldo?”) tasks, with synchronized monitoring of blood pressure, capnography, and heart rate. fNIRS assessed microvascular oxygenation within the frontal, motor, parietal, and occipital cortices, while the middle and posterior cerebral arteries (MCA/PCA) were insonated using TCD. A 16-channel EEG set-up was placed according to the 10–20 system. Wilcoxon signed-rank tests were used to compare physiological responses between the active and resting phases of the tasks, while cross-correlations with zero legs compared cerebral and systemic hemodynamic responses across both tasks. ResultsTime-frequency analysis demonstrated a reduction in alpha and low beta band power in electrodes C3/C4 during finger tapping (p<0.045) and all electrodes during the Waldo task (all p<0.001). During Waldo, cross-correlation analysis demonstrated the change in oxygenated hemoglobin and cerebral blood velocity had a moderate-to-strong negative correlation with systemic physiological influences, highlighting the measured change resulted from neuronal input. Deoxygenated hemoglobin displayed the greatest negative cross-correlation with the MCA/PCA within the motor cortices and visual during the motor and visual tasks, respectively (range:0.54, -0.82). ConclusionsThis investigation demonstrated the feasibility of the proposed EEG-fNIRS-TCD response to comprehensively assess the NVC response within human, specifically quantifying the real-time temporal synchrony between neuronal activation (EEG), microvascular oxygenation changes (fNIRS), and conduit artery velocity alterations (TCD).

Normalization of Oscillating Flow Pattern on Transcranial Duplex Colour-coded Doppler.

Normalization of Oscillating Flow Pattern on Transcranial Duplex Colour-coded Doppler.

Transcranial doppler to detect high-risk PFO and predict decompression illness in divers

Abstract Background It has not yet been clearly demonstrated whether it is feasible to diagnose patent foramen ovale (PFO) using transcranial doppler (TCD) and to use it in strategies to prevent decompression illness (DCI) in self-contained breathing apparatus (SCUBA) divers. Purpose DIVER-PFO study confirmed that high-risk PFO is associated with an increased risk of DCI in SCUBA divers. In this prespecified post-hoc analysis, we aimed to prospectively evaluate the accuracy of TCD to diagnose high-risk PFO and to predict the occurrence of DCI. Methods Eighty-two consecutive divers (mean age; 41 years, male 80.5%) underwent transesophageal echocardiogram (TEE) and TCD with a saline bubble test to determine the presence of PFO and were subsequently divided into high-risk and low-risk groups by TEE findings. Divers in the high-risk PFO group included those with the following conditions: PFO with atrial septal aneurysm, hypermobility, PFO size ≥2 mm, or right to left shunt at resting state. The enrolled divers were then followed-up using a self-reported questionnaire through e-mail or telephone interview for 3 years, while they were blinded to their PFO status. The primary endpoint of the study was PFO-related DCI, comprising cases of cutaneous or neurologic DCI, DCI symptoms requiring hyperbaric chamber therapy, DCI symptoms within 30 minutes after surfacing, or unexplained death occurring within 2 weeks after diving. Results PFO was detected in 47 (57.3%) and 59 (72.0%) divers by TCD and TEE, respectively. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of TCD were 68.3%, 67.8%, 69.6% 85.1%, and 45.7% for the diagnosis of PFO, and 65.9%, 82.8%, 56.6%, 51.1% and 85.7% for the diagnosis of high-risk PFO, respectively. PFO-related DCI occurred in 9 divers in the PFO group (PFO vs non-PFO: 6.4 vs 0.7 incidences per 10,000 person dives; p=0.03) during a mean follow-up of 25.6 months. Integrated time-dependent Area Under the Curves for TCD and TEE to predict DCI occurrence using Cox’s proportional hazards regression model were 0.714 and 0.675, respectively. Conclusions TCD was moderately accurate to diagnose high-risk PFO in divers. However, it predicted DCI as much as TEE.Study flowIncidence of DCI in the PFO vs No PFO

Intraoperative transfontanelle ultrasonography for pediatric patients.

Cerebral blood flow (CBF) plays a vital role in delivering cerebral oxygen, and the accurate assessment of CBF is crucial for the intraoperative management of critically ill infants. Although the direct measurement of CBF is challenging, CBF velocity (CBFV) can be assessed using transcranial Doppler. Recent advances in point-of-care ultrasound have introduced brain ultrasound as a feasible intraoperative option, in which transfontanelle ultrasonography (TFU) has been applied to measure the CBFV through the anterior fontanelle. However, the intraoperative application of TFU in pediatric patients remains limited. The present review highlights the procedural aspects and clinical applications of TFU for anesthetic and intensive care management in pediatric patients. TFU facilitates the visualization of cerebral vessels and allows a noninvasive assessment of cerebral hemodynamics. The clinical significance of TFU involves its usefulness in various clinical scenarios, including monitoring CBF during cardiac surgery, assessing fluid responsiveness, and estimating intracranial pressure. TFU also enables the detection of cerebral emboli and the evaluation of anatomical abnormalities such as hydrocephalus or intracranial hemorrhage. TFU has demonstrated potential as an invaluable tool in pediatric care, despite limited familiarity among anesthesiologists. Additional research is needed to explore the associations between CBF and clinical outcomes, focusing on autoregulation, the impact of physiological changes, the associations of TFU findings with other brain monitoring tools such as electroencephalography, cerebral oximetry, and the implications of microemboli. TFU is a significant advancement and valuable tool for noninvasively assessing cerebral hemodynamics and CBF in pediatric patients with open fontanelles.

Deep learning and Diagnostic value of cardiac cine MRI for assessing patent foramen ovale in patients with cerebral disorders compared with cTCD

Abstract Purpose To investigate the clinical feasibility of cardiac MRI (CMRI) cine technology using deeplearning without contrast for diagnosis and classification of patent foramen ovales (PFOs) in patients with cerebral disorders. Materials and Methods Fourty-four patients (24 males and 20 females; mean age, 41.3 years; range, 21-64 years) with cerebral disorders underwent both contrast transcranial doppler sonography (cTCD) and non-enhanced CMRI examinations between October 2019 and March 2020. and datas from 335 patients were collected by 2023.CMRI was performed with a 3.0T MR scanner by using OBL FIESTA CINE 4CH sequence. The scanning direction was perpendicular to the interatrial septum (IAS) slice. The obtained MR images were analyzed by AW station 4.7 and the pseudo-color coding was also performed according to the different phases. The condition of the blood shunt was observed and recorded by using deep learning, including measuring the length and width of the PFO and observing whether it was complicated with IAS aneurysm or secondary septum thickening. Results Thirty-nine of 44 patients with cerebral disorders were confirmed with positive RLS by cTCD test, and 37 of the 39 patients were diagnosed with a PFO at CMRI. Two of 5 patients with negative cTCD test were also diagnosed with a PFO at CMRI. Compared with cTCD as a standard, CMRI had a sensitivity of 94.9%, specificity of 60.0%, accuracy of 90.9%, positive predictive value of 94.9%, negative predictive value of 60.0%, and AUC of 0.774. Based on the pseudo-color coding, the right-to-left color jet was observed in 34 patients, and the two-way shunting was found in 5 patients. The IAS aneurysm and secondary septum thickening were found in 5 and 3 patients (11.4% and 6.8%). The maximum diameters of PFOs ranged from 1.7 mm to 16.8 mm and the mean diameter was 5.4±3.4 mm. Conclusion By using deep learning,CMRI cine technology without contrast provided a noninvasive and excellent method for PFO identification, evaluation and classification, with both high sensibility (92.85%) and concordance (90.9%) when compared to cTCD.PFO types

Longitudinal assessment of transcranial Doppler imaging in children with sickle cell disease without neurological symptoms

IntroductionStroke is one of the most devastating complications of sickle cell disease (SCD). Transcranial Doppler Imaging (TCDI) is the least invasive screening method to predict patients at risk for developing stroke in the disease. After a 10-year follow-up, we longitudinally assessed the TCDI in children with SCD without neurological symptoms.Methods25 out of 43 pediatric patients with SCD studied 10-year previously were recruited. The remaining 18 patient were not available for follow-up, but their initial data are presented for comparison. TCDI scanning was carried out using a phased-array transducer of 1–3 MHz through the trans-temporal window. Peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged mean of the maximum velocity (TAMMV), resistive index (RI), and pulsatility index (PI) were obtained in the anterior and posterior Circle of Willis vessels.ResultsThe highest initial and follow-up TAMMV (mean ± SD) were: 77.3 ± 20.9 and 71.6 ± 9.9 in the t-ICA, 94.3 ± 25.8 and 82 ± 18.2 in the MCA, 76.6 ± 25.6 and 70.6 ± 10.7 in the ACA, and 59.1 ± 15.8 and 63.9 ± 8.5 in the PCA, respectively. There was no statistically significant difference between initial and follow-up SCD data for all vascular parameters in all vessels on each side (P > 0.05) except for RI and PI (P < 0.05). There was significant correlation between TAMMV, PSV, and EDV (P = 0.001).ConclusionThere are no absolute Doppler velocity changes between the initial and follow-up period over the years. There is a possibility that PSV and EDV could be used in parallel with TAMMV Subclinical vascular degeneration is not suggested by these vascular measures.

Comparing cerebral microembolisation patterns between high power short duration and pulsed field ablation techniques using artificial intelligence based robotic transcranial doppler monitoring

Abstract Thromboembolism is a rare (&amp;lt;1%) complication of atrial fibrillation (AF) ablation , but the incidence of silent ischaemic lesions (SIL) is 5-15% (1). Artificial intelligence (AI)-based robotic transcranial Doppler (r-TCD) enables real-time cerebral embolisation detection. We aimed to investigate the cerebral microembolization signal (MES) load with r-TCD of patients undergoing PF ablation, comparing the number of detected MES-s between 90 W radiofrequency (RFA) "very high power short duration (vHPSD) ablation" and "pulsed field ablation (PFA)" techniques. Our interim analysis included r-TCD registratums of 26 patients. 16 interventions were performed with VHPSD, 10 with PFA, during which we recorded the flow curve of the arteria cerebri media (ACM) bilaterally with r-TCD and analyzed the MES-s quantitatively and qualitatively with AI-based embolisation detection software. Postoperative cranial MRI exams were performed. Continuous variables were compared between the groups using a two-sample t-test, and categorical variables were compared using a Fisher exact test. The MES load by the different pulmonary veins was compared using Wilcoxon test and Bonferroni correction. A p-value below 0,05 was considered significant. The two groups were comparable regarding baseline parameters (mean age: 63 vs.58 p=0,253; EF:59% vs.62 .2% p=0,33). Ablations with vHPSD were significantly longer compared to PFA (88,7 min vs. 54,7 min p&amp;lt;0,001), left atrial time was significantly shorter with PFA (52,1 min vs. 29 min p&amp;lt;0 001), but the fluoroscopic time was significantly longer (5,4 min vs. 9,3 min p=0,009) during ablation with PFA. Neither solid emboli, nor ischaemic lesion or neurological deficit was detected. During the ablations, we saw an average of 246 gas MES-s with PFA and 138 with RFA (p=0,216). During PFA we analyzed the MES load per pulmonary vein: by the left superior vein we detected a median of 56,5 (IQR: 21,5-116,5), by the left inferior there were a median of 23 MES-s (IQR: 4,5 115,5), by the right inferior a median of 32 (IQR: 12-84,5), and by the right superior a median of 22,5(IQR: 8,5-70) respectively, p=0,03. While comparing each veins to each other, by the right vs. left superior vein, the p value resulted 0,01. On an initial sample,we detected known differences in the procedural parameters of the two interventions. There tended to be more MES-s during PFA, but this difference was not significant. Regarding the MES load by the ablation of different pulmonary veins, we found a significant overall difference between the MES load by the four veins, especially between the left and right superior vein. A larger number of interventions and r-TCD registratums is needed to determine the cerebral safety of PFA compared to RFA.

Role of clipping in aneurysmal subarachnoid hemorrhage: a post hoc analysis of the Earlydrain trial

The choice between clipping and coiling of ruptured cerebral aneurysms in subarachnoid hemorrhage (SAH) remains controversial. The recently published Earlydrain trial provides the opportunity to analyze the latest clip-to-coil ratio in German-speaking countries and to evaluate vasospasm incidence and explorative outcome measures in both treatment modalities. We performed a post hoc analysis of the Earlydrain trial, a multicenter randomized controlled trial investigating the use of an additional lumbar drain in aneurysmal SAH. The decision whether to clip or to coil the ruptured aneurysm was left to the discretion of the participating centers, providing a real-world insight into current aneurysm treatment strategies. Earlydrain was performed in 19 centers in Germany, Switzerland, and Canada, recruiting 287 patients with aneurysmal SAH of all severity grades. Of these, 140 patients (49%) received clipping and 147 patients (51%) coiling. Age and clinical severity based on Hunt-Hess/WFNS grades and radiological criteria were similar. Clipping was more frequently used for anterior circulation aneurysms (55%), whereas posterior circulation aneurysms were mostly coiled (86%, p < 0.001). In high-volume recruiting centers, 56% of patients were treated with clipping, compared to 38% in other centers. A per-year analysis showed a stable and balanced clipping/coiling ratio over time. Regarding vasospasm, 60% of clipped versus 43% of coiled patients showed elevated transcranial Doppler criteria (p = 0.007), reflected in angiographic vasospasm rates (51% vs. 38%, p = 0.03). In contrast to the Earlydrain main results establishing the superiority of an additional lumbar drain, explorative outcomes after clipping and coiling measured by secondary infarctions, mortality, modified Rankin Score, Glasgow Outcome Scale Extended, or Barthel-Index showed no significant differences after discharge and at six months. In clinical practice, aneurysm clipping is still a frequently used method in aneurysmal SAH. Apart from a higher rate of vasospasm in the clipping group, an exploratory outcome analysis showed no difference between the two treatment methods. Further development of periprocedural treatment modalities for clipped ruptured aneurysms to reduce vasospasm is warranted.

Ventilatory response to head-down-tilt in healthy human subjects.

Postural fluid shifts may directly affect respiratory control via a complex interaction of baro- and chemo-reflexes, and cerebral blood flow. Few data exist concerning the steady state ventilatory responses during head-down tilt. We examined the cardiorespiratory responses during acute 50° head-down tilt (HDT) in 18 healthy subjects (mean [SD] age 27 [10] years). Protocol 1 (n=8, two female) was 50° HDT from 60° head-up posture sustained for 10min, while exposed to normoxia, normoxic hypercapnia (5% CO2), hypoxia (12% inspired O2) or hyperoxic hypercapnia (95% O2, 5% CO2). Protocol 2 (n=10, four female) was 50° HDT from supine, sustained for 10min, while breathing either medical air or normoxic hypercapnic (5% CO2) gas. Ventilation ( , pneumotachograph), end-tidal O2 and CO2 concentration and blood pressure (Finapres) were measured continuously throughout each protocol. Middle cerebral artery blood flow velocity (MCAv; transcranial Doppler) was also measured during protocol 2. Ventilation increased significantly (P<0.05) compared to baseline during HDT in both hyperoxic hypercapnia (protocol 1 by mean [SD] 139 [26]%) and normoxic hypercapnia (protocol 1 by mean [SD] 131 [21]% and protocol 2 by 129 [23]%), despite no change in or from baseline. No change in was observed during HDT with medical air or hypoxia, and there was no significant change in MCAv during HDT compared to baseline. The absence of change in cerebral blood flow leads us to postulate that the augmented ventilatory response during steep HDT may involve mechanisms related to cerebral venous pressure and venous outflow.

The relationships between age, sex and exercise intensity on cerebral artery haemodynamics during isometric handgrip exercise.

Age and sex may alter the cerebral blood flow (CBF) responses to acute isometric exercise, via associated elevations in mean arterial pressure (MAP) and sympathetic activation. Our aim was to determine the relationships between age, sex and exercise intensity on cerebrovascular responses to isometric handgrip exercise. In 78 healthy adults (18-80 years, N=42 female), cerebrovascular responses were assessed during two minute isometric exercise bouts at three intensities (15, 30, 45% maximal voluntary contraction). Intracranial responses of the middle cerebral artery (MCA) and posterior cerebral artery (PCA) velocity (v) were measured using transcranial Doppler ultrasound. Extracranial responses of the internal carotid artery (ICA) and vertebral artery (VA) were assessed using Duplex ultrasound. Cardiopulmonary haemodynamic and neural parameters were measured throughout, including muscle sympathetic nerve activity, end-tidal carbon dioxide, and MAP. There were significant positive relationships between exercise intensity and the cerebral responses of the MCAv (P<0.001) and PCAv (P=0.005). There were no effects of intensity on ICA and VA responses (P>0.05), despite intensity-dependent increases in MAP (P<0.001). The increased MCAv response to exercise was blunted with advancing age (P=0.01) with no influence of sex (P=0.86). The present study provides data on age, sex and intensity specific relationships with intracranial and extracranial cerebrovascular responses to isometric exercise. Despite similar ICA, VA, and PCA responses, MCAv responses were attenuated with advancing age during handgrip exercise with no sex dependent influence. Further, intracranial responses were intensity dependent, whereas extracranial blood flow, shear-stress and velocity responses were similarly increased at all intensities during handgrip exercise.

Is muscle sympathetic nerve activity associated with cerebral blood velocity? A partial coherence analysis.

Despite some evidence, the role of sympathetic nerve activity in the regulation of cerebral blood flow remains controversial. In humans, muscle sympathetic nervous activity (MSNA) is the only direct measure of sympathetic nerve activity that can be recorded with sufficient temporal resolution, to allow association with dynamic regulation of cerebral blood velocity (CBv). This study tested the hypothesis that MSNA is associated with the regulation of CBv at rest and during different physiological maneuvers. Nine healthy subjects underwent two sympathoexcitatory maneuvers: i) isometric handgrip exercise (HGR), and ii) cold pressor test (CPT). Mean arterial pressure (MAP, oscillometric method), CBv (transcranial Doppler ultrasound), and MSNA (microneurography) were measured continuously during experimental protocols. Ordinary and partial coherences of the MAP, CBv and MSNA time series were estimated by transfer function analysis in the low-frequency range (LF: 0.07-0.20 Hz), using MAP and MSNA as inputs and CBv as the output variable. When the influence of MSNA was taken into account, the partial coherences between MAP and CBv were considerably reduced at baseline (P<0.01), HGR (P=0.02), and CPT (P<0.01). Similarly, when the influence of MAP was taken into account, the coherence between MSNA and CBv was considerably reduced at baseline (P<0.01), HGR (P=0.02), and CPT (P=0.01), leading to the conclusion, that MSNA was associated to dynamic regulation of CBv. Partial coherence analysis is a promising method for assessing the influence of the sympathetic nervous system on cerebral hemodynamics.