Carotid Flow Research Articles

Cardiopulmonary Resuscitation of Asystolic Newborn Lambs Prior to Umbilical Cord Clamping; the Timing of Cord Clamping Matters!

Background: Current guidelines recommend immediate umbilical cord clamping (UCC) for newborns requiring chest compressions (CCs). Physiological-based cord clamping (PBCC), defined as delaying UCC until after lung aeration, has advantages over immediate UCC in mildly asphyxiated newborns, but its efficacy in asystolic newborns requiring CC is unknown. The aim of this study was to compare the cardiovascular response to CCs given prior to or after UCC in asystolic near-term lambs. Methods: Umbilical, carotid, pulmonary, and femoral arterial flows and pressures as well as systemic and cerebral oxygenation were measured in near-term sheep fetuses [139 ± 2 (SD) days gestation]. Fetal asphyxia was induced until asystole ensued, whereupon lambs received ventilation and CC before (PBCC; n = 16) or after (n = 12) UCC. Epinephrine was administered 1 min after ventilation onset and in 3-min intervals thereafter. The PBCC group was further separated into UCC at either 1 min (PBCC1, n = 8) or 10 min (PBCC10, n = 8) after return of spontaneous circulation (ROSC). Lambs were maintained for a further 30 min after ROSC. Results: The duration of CCs received and number of epinephrine doses required to obtain ROSC were similar between groups. After ROSC, we found no physiological benefits if UCC was delayed for 1 min compared to immediate cord clamping (ICC). However, if UCC was delayed for 10 min after ROSC, we found significant reductions in post-asphyxial rebound hypertension, cerebral blood flow, and cerebral oxygenation. The prevention of the post-asphyxial rebound hypertension in the PBCC10 group occurred due to the contribution of the placental circulation to a low peripheral resistance. As a result, left and right ventricular outputs continued to perfuse the placenta and were evidenced by reduced mean pulmonary blood flow, persistence of right-to-left shunting across the ductus arteriosus, and persistence of umbilical arterial and venous blood flows. Conclusion: It is possible to obtain ROSC after CC while the umbilical cord remains intact. There were no adverse effects of PBCC compared to ICC; however, the physiological changes observed after ROSC in the ICC and early PBCC groups may result in additional cerebral injury. Prolonging UCC after ROSC may provide significant physiological benefits that may reduce the risk of harm to the cerebral circulation.

POCUS and POCDUS: essential tools for the evaluation and management of carotid artery pseudoaneurysms after a gunshot wound

BackgroundEvaluation of asymptomatic penetrating vascular injuries can be done with Point-of-care ultrasound (POCUS) and Point-of-care Doppler ultrasound (POCDUS).Case presentationA 21-year-old woman was admitted to the Emergency Department with a small wound and pain on the left side of her neck. The patient stated she was standing outside her home and suddenly felt acute pain in the neck. She denied trauma or being assaulted and reported no significant past medical or surgical history. On physical exam the only positive finding was a small gunshot entry wound on the left side of her neck without hard signs of vascular injury. Bedside POCUS demonstrated soft tissue swelling and a hematoma next to the left carotid artery. A round in shape bullet was visualized in contact with the posterior left common carotid artery wall and two small saccular pseudoaneurysms were seen at left common carotid artery wall. POCDUS showed a patent left carotid artery and turbulent flow in the two saccular aneurysms. A computed tomography angiogram (CTA) was performed confirming the findings and a stent in left carotid artery was placed. The patient tolerated the procedure well and was discharged 4 days after the procedure. At the sixth month follow-up, Doppler ultrasound showed patent stent and resolution of the muscular hematoma.ConclusionsPenetrating trauma-related vascular injuries are complex cases to handle within an acute setting. POCUS and POCDUS are increasingly being used for the workup and decision-making process of gunshot-related vascular injuries to the neck and are a fundamental part of the follow-up after definitive therapy.

Correlation of internal carotid artery diameter and carotid flow with asymmetry of the circle of Willis

BackgroundThe purpose of this study was to clarify the effect of asymmetric COW variants on carotid flow changes, and proposed an easy estimate of the representative carotid flow volume for accurate numerical simulation.MethodsA total of 210 healthy adults receiving magnetic resonance angiography and carotid duplex sonography were included. Three anterior cerebral artery asymmetry (AA) groups were defined based on the diameter ratio difference (DRD) of bilateral A1 segments: AA1 group, one-side A1 aplasia; AA2, A1 DRD ≥ 50%; AA3, A1 DRD between 10 and 50%. Similarly, 3 posterior communicating artery (PcomA) asymmetry (PA) groups were defined: PA1 group, one fetal-origin posterior cerebral artery and absent contralateral PcomA; PA2, PcomA DRD ≥ 50%; PA3, PcomA DRD between 10 and 50%.ResultsWith A1 asymmetry, the ICA diameter of the dominant A1 is significantly greater than the contralateral side. Significant differences of bilateral ICA flow were present in the AA1 and AA2 groups (mean flow difference 42.9 and 30.7%, respectively). Significant bilateral ICA diameter and flow differences were only found in the PA1 group. Linear regression analysis of ICA diameter and flow found a moderately positive correlation between ICA diameter and flow in all AA groups, with a 1 mm increment in vessel diameter corresponding to a 62.6 ml increment of flow volume. The product of bilateral ICA diameter and flow volume difference (ICA-PDF) could be a potential discriminator with a cutoff of 4.31 to predict A1 asymmetry ≥50% with a sensitivity of 0.81 and specificity of 0.76.ConclusionsThe study verifies that A1 asymmetry causes unequal bilateral carotid inflow, and consequently different bilateral ICA diameters. Adjustment of the inflow boundary conditions according to the COW variants would be necessary to improve the accuracy of numerical simulation.

Flow modification on the internal carotid artery bifurcation region and A1 segment after M1-internal carotid artery flow diverter deployment

BackgroundClinical and hemodynamic consequences of flow diverters extending from the M1 to the internal carotid artery (ICA), covering the A1 segment, have rarely been investigated. We aimed to provide angiographic...

SUN-577 Effect of Growth Hormone Replacement on Metabolic Profile and Vascular System in Adult Patients with Congenital Hypopituitarism

Introduction: Growth Hormone (GH) stimulates two distinct processes: anabolic effect of GH on growth through IGF1, and catabolic effect of GH stimulating lipolysis. GH deficiency (GHD) in adulthood is characterized with abnormal body composition, impairment of physical capacity and lipid and glycemic metabolism, beyond increase cardiovascular risk (CVR) factors. While in acquired hypopituitarism, GHD is always associated with CVR in several studies and demonstrated human recombinant growth hormone replacement (hrGHr) improves CVR. In congenital hypopituitarism (CH), however, the consequences of GHD and hrGHr in adulthood are unclear. Objective: To evaluate daily hrGHr in metabolic profile and vascular system in adult patients with CH. Patients and Methods: Fifty-nine adults with CH were selected for the study. They were divided into 2 groups: 1- hrGHr: 15 male, 17 female with median age 35,8 yrs, hrGHr in adult life with 7.2 yrs median time in the dose of approximately 1U per day in order to keep IGF1 in the normal range for age and sex; 2- Without hrGHr: 12 male, 15 female with 38,4 yrs median age and without hrGHr in adult life of 10.6 yrs median time. Thirty-two healthy volunteers were selected as controls. Anthropometric parameters, dual-energy X-ray absorptiometry (DXA), lipid and glycemic profile, and structural and functional parameters of the arterial vessels (carotid intima media thickness, arterial stiffness and flow mediated dilation) were evaluated and compared between the groups. Results: In patients with rhGHr the abdominal waist/height (AW/H) ratio (0,49 ± 0,06), the fat percentage (30,7 ± 10,4) and fat index (7,6 ± 3,7) were lower than the group without replacement (p= <0,001, p= <0,001 and p= 0,028, respectively). The low values of the CA/H ratio, fat percentage and fat index were independent of the diagnosis ACTH deficiency with corticosteroid replacement. Higher triglycerides (111,7 ± 62,4) and lower HDLc (49,5 ± 19,1) levels in patients without hrGHr compared to controls (p= 0,020 and p= 0,005, respectively) were observed. There was no statistical difference between glycemic profile, metabolic comorbidities and structural and function parameters of the arterial vessels between groups and controls. Conclusions: GHD in CH does not lead to accelerated premature atherosclerosis and arteriosclerosis. The hrGHr in adults with CH have beneficial effects on lipid profile and body composition and hrGHr in adulthood should be individualized.

Volumetric Carotid Flow Characteristics in Doppler Ultrasonography in Healthy Population Over 65 Years Old.

Background: Carotid flow velocity criteria are well established, with age being a factor influencing measurements. However, there are no volumetric standards for the flow in extracranial arteries. The aim of the study was related to volumetric flow assessment of extracranial arteries in a healthy population >65 years old. Methods: Doppler volumetric measurements of internal carotid (ICA), external carotid (ECA) and vertebral arteries (VA) were performed in 123 healthy volunteers >65 years old and compared with 56 healthy volunteers <65 years old. Results: The continuous decline in cerebral blood flow (CBF) volume was observed (p < 0.00001). Volumetric reference values were established in study groups: 1., 65–69 years: 898.5 ± 119.1; 2., 70–74 years: 838.5 ± 148.9; 3., 75–79 years: 805.1 ± 99.3; 4., >80 years: 685.7 ± 112.3 (mL/min). Significant differences were observed between groups: 1 and 3.4, as well as 3 and 4 (p = 0.0295, < 0.000001, 0.00446 respectively). CBF volume decreases gradually with age: 28–64 years—6.2 mL/year (p = 0.0019), 65–75 years—11.4 mL/year (p = 0.0121) and >75 years—14.3 mL/year (p = 0.0074). This is a consequence of flow volume decline in ICA (p = 0.00001) and to lesser extent ECA (p = 0.0011). The decrease of peak systolic (p = 0.002) and end diastolic (p = < 0.00001) velocities in ICA and peak systolic velocity in ECA (p = 0.0017) were observed. Conclusions: CBF decreases with ageing. Volumetric assessment of CBF may play an important additional role in diagnostics of patients with carotid stenosis. Doppler assessment of cerebral flow volume may create an interesting tool for identifying patients with diminished cerebrovascular reserve and higher risk of ischemic symptoms occurrence.

Carotid Artery Flow Time Measured by Point-of-Care Ultrasound Correlates with Volume Changes in Pediatric Hemodialysis Patients

Carotid artery flow time corrected for heart rate (CFTc) correlates with intravascular volume changes in adults but has not been studied adequately in the pediatric population. We studied how fluid status changes correlate with CFTc in pediatric patients undergoing hemodialysis. This prospective observational study involved pediatric patients aged 5–18 y undergoing chronic hemodialysis at a tertiary care children’s hospital in the United States. We measured CFTc by point-of-care ultrasound before and after each hemodialysis session, including passive leg raise. One hundred sixty-eight CFTc measurements were obtained from a total of 21 patient encounters. Post-dialysis CFTc decreased by 21.7 ms (95% confidence interval: 12.3–31.0) (p < 0.001). Pre- and post-dialysis ∆CFTc measurements were proportionally correlated with volume removed in dialysis adjusted for weight (mL/kg) (R2 = 0.224, p = 0.03). There was no significant change in mean CFTc with passive leg raise before or after hemodialysis. In children on hemodialysis, changes in CFTc were moderately correlated with decrease in intravascular volume after hemodialysis.

Adenosine, Lidocaine, and Magnesium Support a High Flow, Hypotensive, Vasodilatory State With Improved Oxygen Delivery and Cerebral Protection in a Pig Model of Noncompressible Hemorrhage

BackgroundNoncompressible hemorrhage is the leading cause of preventable death in military and civilian trauma. Our aim was to examine the effect of adenosine, lidocaine, and magnesium (Mg2+; ALM) on cardiovascular and cerebral function in a porcine hepatic hemorrhage model. Materials and methodsPigs (59.1 ± 0.34 kg) were anesthetized, instrumented, and randomly assigned into sham (n = 6), saline controls (n = 10) or ALM (n = 10) groups before laparoscopic liver resection. After 30 min, groups received 4 mL/kg 3% NaCl ± ALM bolus (Phase 1) followed 60 min later with 3 mL/kg/h 0.9% NaCl ± ALM drip (4 h; Phase 2), then transfusion. Hemodynamics, carotid artery flow, and intracranial pressure were measured continuously. Microdialysis samples were analyzed for metabolites. ResultsSaline controls had 20% mortality (mean survival time: 307 ± 38 min) with no ALM deaths over 6 h. Bolus administration increased mean arterial pressure (MAP) in both groups, and drip led to further increases to 62 ± 10 mmHg in controls compared with a steady fall to 47 ± 8 mmHg in ALM group at 240 min. The lower MAP was associated with a dramatic fall in systemic vascular resistance and improved oxygen delivery. ALM drip significantly increased cardiac output and stroke volume with lower dP/dtMin, indicating a less stiff heart. ALM drip also significantly decreased cerebral perfusion pressure, reduced cerebral oxygen consumption (28%), and reduced brain glycerol (60%), lactate (47%), and relative expression of hypoxia-inducible factor (38%) compared with saline controls. ConclusionsALM therapy improved cardiac function and oxygen delivery by lowering systemic vascular resistance after noncompressible hemorrhage. ALM also appeared to protect the brain at hypotensive MAPs with significantly lower cerebral perfusion pressure, lower O2 consumption, and significantly lower cortical lactate and glycerol levels compared to saline controls.

Common carotid flow velocity is associated with cognitive function after carotid endarterectomy

The relationship between ultrasonographic flow parameters and cognitive function has not been well studied. This study aimed to clarify associations between carotid flow velocity (FV) and cognitive function in patients with a history of carotid endarterectomy (CEA). Ninety-four patients who previously underwent CEA participated in this study. The Neurobehavioral Cognitive Status Examination (Cognistat) and Frontal Assessment Battery (FAB) were adopted to assess cognitive functions at a mean of 6.5 ± 3.2 years after CEA. End-diastolic flow velocity (EDV) of the left and right common carotid artery (CCA) was significantly associated with total Cognistat score (p < 0.001) and total FAB score (p < 0.05). Pulsatility index (PI) of the left CCA was significantly associated with total Cognistat score and total FAB score (p < 0.01). A cut-off right CCA EDV of 14.5 cm/s offered the most reliable predictor of the bottom 25th percentile of total Cognistat score (sensitivity 83.3%, specificity 61.0%, area under the curve (AUC) 0.731, p = 0.0060), while a cut-off left CCA PI of 1.83 was the most reliable predictor of the bottom 25th percentile of total FAB score (sensitivity 73.3%, specificity 60.0%, AUC 0.679, p = 0.0179). Left and right CCA EDV correlated with sub-components of comprehension, construction, judgment, programming (p < 0.01), and conceptualization (p < 0.05). Right CCA EDV correlated with similarity (p < 0.01), repetition, naming, and memory (p < 0.05). Left CCA PI correlated with attention, conceptualization (p < 0.01), repetition, construction, similarity, and mental flexibility (p < 0.05), while right CCA PI correlated with construction (p < 0.05). CCA FV may offer useful markers of cognitive functions in patients with a history of CEA.

Sex Differences in Hemodynamic Response to Acute Passive Heat Exposure

A single bout of passive heat stress elicits an increase in cardiac output, a redistribution of blood flow, and a subsequent increase in conduit vessel shear stress. This increased shear stress acutely improves vascular function in a dose‐dependent manner and potentiates many of the beneficial vascular adaptations that accompany chronic heat therapy. However, physical and physiologic differences exist between sexes and influence the thermoregulatory response to passive heat stress. It is unknown if these sex‐related thermoregulatory differences alter the adaptive shear stimulus accompanying passive heat stress.PurposeTo compare the hemodynamic response to acute passive heat exposure (APHE) between sexes.Methods10 women (W) and 11 men (M) between the ages of 18–31 years completed a one‐hour APHE session immersed to the level of the sternum in 40°C water. W were studied under low hormone conditions. Rectal temperature (Tre), mean arterial pressure (MAP), and brachial and carotid artery hemodynamics (ultrasound) were measured at baseline (seated rest before APHE) and every 15 min throughout APHE. Automated wall‐tracking software was used to determine brachial and carotid diameter, velocity, flow, and total shear rate. Data are reported as mean ± SEM. Subject characteristics, reported as mean ± SD, were compared using unpaired t‐tests. A 2 X 5 mixed model ANOVA was used to compare Tre, MAP, and brachial and carotid hemodynamics across time and between sexes.ResultsBoth body mass (W: 62.9 ± 8.1 kg, M: 74.2 ± 5.1 kg, P &lt; 0.01) and body surface area (W: 1.71 ± 0.14 m2, M: 1.93 ± 0.10 m2, P &lt; 0.001) were lower in W compared to M. W had a higher Tre than M (P &lt; 0.05) at baseline (W: 37.5 ± 0.1°C, M: 37.2 ± 0.1°C) and after 60 min APHE (W: 38.7 ± 0.03°C, M: 38.5 ± 0.1°C). W had a lower MAP than M (P &lt; 0.05) at baseline (W: 85 ± 2 mmHg, M: 88 ± 2 mmHg) and throughout APHE (W: 74 ± 2 mmHg, M: 82 ± 3 mmHg at 60 min APHE). W and M had a similar baseline brachial total shear rate (W: 170 ± 30 1/s, M: 105 ± 19 1/s). Brachial total shear rate was elevated to a greater extent in W than M during APHE (P &lt; 0.01), reaching 651 ± 49 1/s and 396 ± 24 1/s at 60 min APHE, respectively. The sex difference in brachial shear response to APHE was the result of a greater increase in brachial velocity seen in W (+47 ± 6 cm/s) compared to M (+35 ± 4 cm/s) with APHE (P &lt; 0.1). This elevated brachial velocity allowed for a similar increase in brachial blood flow between sexes with APHE (W: +339 ± 53 mL/min, M: +369 ± 37 mL/min) despite the smaller brachial diameter in W compared to M (P &lt; 0.0001) at baseline (W: 0.31 ± 0.01 cm, M: 0.41 ± 0.01 cm) and throughout APHE (W: 0.37 ± 0.01 cm, M: 0.46 ± 0.01cm at 60 min APHE). In contrast, no differences were seen between sexes in carotid total shear rate, flow, velocity, or diameter at baseline or throughout APHE.ConclusionThese data indicate the presence of an artery‐specific sex difference in the hemodynamic response to a single bout of passive heat stress. Although a “threshold” or “dose‐response” relationship between shear stress and vascular adaptation has not been determined, these findings may have implications for sex‐specific vascular adaption accompanying chronic heat therapy.Support or Funding InformationAPS Porter Pre‐Doctoral Fellowship

The relation between aortic stiffness and retinal microvascular flow pulsatility is attenuated by higher vascular resistance in healthy adults

Aortic stiffness is associated with increased risk of cerebrovascular disease and cognitive impairments with aging, although the mechanism that contribute to this link are not well‐defined. Increases in carotid artery flow pulsatility coincide with elevated aortic stiffness and may contribute to microvascular brain damage, but studies confirming augmented flow pulsatility in the downstream microvasculature have been limited. Given the ability to assess the retinal microvasculature non‐invasively in humans and evidence that disease‐ and age‐related alterations in the retinal microvasculature mirror changes in the cerebral microvasculature, we examined the hypothesis that age‐related increases in aortic stiffness would be correlated with higher retinal arteriole flow pulsatility (systolic flow – diastolic flow / mean flow). Among 33 healthy adults (age range: 25–60 years, 47% women), aortic stiffness was assessed by carotid‐femoral pulse wave velocity (CFPWV). Retinal arteriole flow pulsatility was quantified using laser speckle flowgraphy before and during a reduction in retinal vascular resistance via 30 s of diffuse luminance flicker. Multiple regression analysis including CFPWV, mean arterial pressure (MAP), and heart rate (HR) as independent variables demonstrated that lower MAP and HR, but not higher CFPWV, were significant determinants of greater flow pulsatility at baseline (CFPWV: β=0.10, P=0.548; MAP: β= −0.40, P=0.021; HR: β= −0.50, P=0.002; model R2=0.43, P=0.001). However, after reducing retinal vascular resistance (P&lt;0.001) via 30s of diffuse luminance flicker, multiple regression analysis demonstrated that higher CFPWV was a significant determinant of greater retinal arteriole flow pulsatility (β=0.35, P=0.026) in addition to lower MAP (β= −0.54, P=0.001) and HR (β= −0.43, P=0.005) (model R2=0.51, P&lt;0.001). In summary, no relation was observed between higher CFPWV and retinal arteriole flow pulsatility at rest, but a positive relation was observed during arteriole vasodilation. These findings suggest that greater vascular resistance may be an important compensatory mechanism to reduce transmission of flow pulsatility.Support or Funding InformationAHA 17POST33440101, T32 HL07121 NHLBI (P01HL014388), U54 TR001356 and AHA (13DG143400012).

A novel roller pump for physiological flow.

Having physiological correct flow waveforms is a key feature for experimental studies of blood flow, especially in the process of developing and testing a new medical device such as stent, mechanical heart valve, or any implantable medical device that involves circulation of blood through the device. It is also a critical part of a perfusion system for cardiopulmonary bypass and extracorporeal membrane oxygenation procedures. This study investigated the feasibility of a novel roller pump for use in experimental flow phantoms. Flow rates of carotid flow profile measured directly with the ultrasonic flow meter matched well with the reference flow rates programmed into the machine with similarity index of 0.97 and measured versus programmed flow rates at specific time‐points of peak systolic velocity (PSV): 0.894 vs 0.880, end systolic velocity (ESV): 0.333 vs 0.319, and peak diastolic velocity (PDV): 0.514 vs 0.520 L/min. Flow rates derived from video analysis of the pump motion for carotid, suprarenal, and infrarenal flows also matched well with references with similarity indices of 0.99, 0.99, and 0.96, respectively. Measured flow rates (mean/standard deviation) at PSV, ESV, and PDV time‐points for carotid: 0.883/0.016 vs 0.880, 0.342/0.007 vs 0.319, and 0.485/0.009 vs 0.520; suprarenal: 3.497/0.014 vs 3.500, 0.004/0.003 vs 0, and 1.656/0.073 vs 1.453; infrarenal: 4.179/0.024 vs 4.250, −1.147/0.015 vs −1.213, and 0.339/0.017 vs 0.391 L/min, respectively. The novel roller pump is suitable for benchtop testing of physiological flow.

Balanced Biventricular Assist Versus Extracorporeal Membrane Oxygenation in Cardiac Arrest.

Mechanical assist devices in refractory cardiac arrest are increasingly employed. We compared the hemodynamics and organ perfusion during cardiac arrest with either veno-arterial extracorporeal membrane oxygenation (ECMO) or biventricular assisted circulation combining left- and right-sided impeller devices (BiPella) in an acute experimental setting. Twenty pigs were randomized in two equal groups receiving circulatory support either by ECMO or by BiPella during 40 minutes of ventricular fibrillation (VF) followed by three attempts of cardioversion, and if successful, 60 minute observation with spontaneous, unsupported circulation. Hemodynamic variables were continuously recorded. Tissue perfusion was evaluated by fluorescent microsphere injections. Cardiac function was visualized by intracardiac echocardiography. During VF device output, carotid flow, kidney perfusion, mean aortic pressure (AOPmean), and mean left ventricular pressure (LVPmean) were all significantly higher in the ECMO group, and serum-lactate values were lower compared with the BiPella group. No difference in myocardial or cerebral perfusion was observed between groups. In 15 animals with sustained cardiac function for 60 minutes after return of spontaneous circulation, left ventricular subendocardial blood flow rate averaged 0.59 ± 0.05 ml/min/gm during VF compared with 0.31 ± 0.07 ml/min/gm in five animals with circulatory collapse (p = 0.005). Corresponding values for the midmyocardium was 0.91 ± 0.06 vs. 0.65 ± 0.15 ml/min/gm (p = 0.085). Both BiPella and ECMO could sustain vital organ function. ECMO provided a more optimal systemic circulatory support related to near physiologic output. Myocardial tissue perfusion and sustained cardiac function were related to coronary perfusion pressure during VF, irrespective of mode of circulatory support.

Neurovascular effects of umbilical cord blood-derived stem cells in growth-restricted newborn lambs

BackgroundNeonatal ventilation exacerbates brain injury in lambs with fetal growth restriction (FGR), characterized by neuroinflammation and reduced blood-brain barrier integrity, which is normally maintained by the neurovascular unit. We examined whether umbilical cord blood stem cell (UCBC) treatment stabilized the neurovascular unit and reduced brain injury in preterm ventilated FGR lambs.MethodsSurgery was performed in twin-bearing pregnant ewes at 88 days’ gestation to induce FGR in one fetus. At 127 days, FGR and appropriate for gestational age (AGA) lambs were delivered, carotid artery flow probes and umbilical lines inserted, lambs intubated and commenced on gentle ventilation. Allogeneic ovine UCBCs (25 × 106 cells/kg) were administered intravenously to lambs at 1 h of life. Lambs were ventilated for 24 h and then euthanized.ResultsFGR (n = 6) and FGR+UCBC (n = 6) lambs were growth restricted compared to AGA (n = 6) and AGA+UCBC (n = 6) lambs (combined weight, FGR 2.3 ± 0.4 vs. AGA 3.0 ± 0.3 kg; p = 0.0002). UCBC therapy did not alter mean arterial blood pressure or carotid blood flow but decreased cerebrovascular resistance in FGR+UCBC lambs. Circulating TNF-α cytokine levels were lower in FGR+UCBC vs. FGR lambs (p < 0.05). Brain histopathology showed decreased neuroinflammation and oxidative stress, increased endothelial cell proliferation, pericyte stability, and greater integrity of the neurovascular unit in FGR+UCBC vs. FGR lambs.ConclusionsUmbilical cord blood stem cell therapy mitigates perinatal brain injury due to FGR and ventilation, and the neuroprotective benefits may be mediated by stabilization of the neurovascular unit.

Zibotentan, an Endothelin A Receptor Antagonist, Prevents Amyloid-β-Induced Hypertension and Maintains Cerebral Perfusion.

Cerebral blood flow is reduced in Alzheimer’s disease (AD), which is associated with mid-life hypertension. In people with increased cerebral vascular resistance due to vertebral artery or posterior communicating artery hypoplasia, there is evidence that hypertension develops as a protective mechanism to maintain cerebral perfusion. In AD, amyloid-β (Aβ) accumulation may similarly raise cerebral vascular resistance by upregulation of the cerebral endothelin system. The level of endothelin-1 in brain tissue correlates positively with Aβ load and negatively with markers of cerebral hypoperfusion such as increased vascular endothelial growth factor. We previously showed that cerebroventricular infusion of Aβ40 exacerbated pre-existing hypertension in Dahl rats. We have investigated the effects of 28-day cerebral infusion of Aβ40 on blood pressure and heart rate and their variability; carotid flow; endothelin-1; and markers of cerebral oxygenation, in the (normotensive) Wistar rat, and the modulatory influence of the endothelin A receptor antagonist Zibotentan (ZD4054). Cerebral infusion of Aβ caused progressive rise in blood pressure (p < 0.0001) (paired t-test: increase of 3 (0.1–5.6) mmHg (p = 0.040)), with evidence of reduced baroreflex responsiveness, and accumulation of Aβ and elevated endothelin-1 in the vicinity of the infusion. Oral Zibotentan (3 mg/kg/d, administered for 31 d) abrogated the effects of Aβ40 infusion on baroreflex responsiveness and blood pressure, which declined, although without reduction in carotid blood flow, and Zibotentan caused uncoupling of the positive linear relationship between endothelin-1 and vascular endothelial growth factor, which as a sensor of tissue oxygenation would be expected to increase if there were hypoperfusion.

A Carotid Doppler Patch Accurately Tracks Stroke Volume Changes During a Preload-Modifying Maneuver in Healthy Volunteers.

Objectives:Detecting instantaneous stroke volume change in response to altered cardiac preload is the physiologic foundation for determining preload responsiveness.Design:Proof-of-concept physiology study.Setting:Research simulation laboratory.Subjects:Twelve healthy volunteers.Interventions:A wireless continuous wave Doppler ultrasound patch was used to measure carotid velocity time integral and carotid corrected flow time during a squat maneuver. The Doppler patch measurements were compared with simultaneous stroke volume measurements obtained from a noninvasive cardiac output monitor.Measurements and Main Results:From stand to squat, stroke volume increased by 24% while carotid velocity time integral and carotid corrected flow time increased by 32% and 9%, respectively. From squat to stand, stroke volume decreased by 13%, while carotid velocity time integral and carotid corrected flow time decreased by 24% and 10%, respectively. Both changes in carotid velocity time integral and corrected flow time were closely correlated with changes in stroke volume (r2 = 0.81 and 0.62, respectively). The four-quadrant plot found a 100% concordance rate between changes in stroke volume and both changes in carotid velocity time integral and changes in corrected flow time. A change in carotid velocity time integral greater than 15% predicted a change in stroke volume greater than 10% with a sensitivity of 95% and a specificity of 92%. A change in carotid corrected flow time greater than 4% predicted a change in stroke volume greater than 10% with a sensitivity of 90% and a specificity of 92%.Conclusions:In healthy volunteers, both carotid velocity time integral and carotid corrected flow time measured by a wireless Doppler patch were useful to track changes in stroke volume induced by a preload-modifying maneuver with high sensitivity and specificity.

Assessment of the carotid artery Doppler flow time in patients with acute upper gastrointestinal bleeding.

INTRODUCTION:Because of the subjectivity and ambiguity of the noninvasive measurements and limited use of invasive ones, there is an impending need for a real-time, fast, inexpensive, and reproducible noninvasive measurement method in acute upper gastrointestinal (GI) bleeding with active bleeding in emergency services.AIMS:In this study, we aimed to evaluate the effect of bedside carotid artery flow time (CFT) measurement before and after the passive leg raising (PLR) maneuver on the determination of active bleeding in patients admitted to the emergency department (ED) with upper GI bleeding.MATERIALS AND METHODS:This prospective case–control study was conducted in the ED of a training and research hospital with upper GI bleeding. Patients were placed in the supine position to perform bedside carotid Doppler ultrasonography before starting treatment. CFT, corrected CFT (CFTc), and carotid artery Doppler flow velocity were measured. After then performed PLR, the same parameters were measured again.RESULTS:A total of 94 patients, including 50 patients with GI bleeding and 44 healthy volunteers as control group were included in the study. CFT and CFTc were shorter in the patient group than the control group (P < 0.001, P = 0.004, respectively). After PLR, there were statistically significant differences in change in the CFT (ΔCFT) and change in the corrected CFT (ΔCFTc) between the groups (P = 0.001, P < 0.001). There were also statistically significant differences in ΔCFT and ΔCFT between the patients with active bleeding and the nonbleeding ones (P = 0.01, P = 0.005, respectively). Area under curve to detect active bleeding for ΔCFT and ΔCFTc were calculated as 0.801 (95% confidence interval [CI]: 0.65–0.95) and 0.778 (95% CI: 0.63–0.91), respectively.CONCLUSION:The corrected carotid Doppler flow time measurements in patients with GI bleeding at the time of presenting to the emergency department can be helpful to interpret the active bleeding.

Highly accelerated 4D flow cardiovascular magnetic resonance using a pseudo-spiral Cartesian acquisition and compressed sensing reconstruction for carotid flow and wall shear stress

Background4D flow cardiovascular magnetic resonance (CMR) enables visualization of complex blood flow and quantification of biomarkers for vessel wall disease, such as wall shear stress (WSS). Because of the inherently long acquisition times, many efforts have been made to accelerate 4D flow acquisitions, however, no detailed analysis has been made on the effect of Cartesian compressed sensing accelerated 4D flow CMR at different undersampling rates on quantitative flow parameters and WSS.MethodsWe implemented a retrospectively triggered 4D flow CMR acquisition with pseudo-spiral Cartesian k-space filling, which results in incoherent undersampling of k-t space. Additionally, this strategy leads to small jumps in k-space thereby minimizing eddy current related artifacts. The pseudo-spirals were rotated in a tiny golden-angle fashion, which provides optimal incoherence and a variable density sampling pattern with a fully sampled center. We evaluated this 4D flow protocol in a carotid flow phantom with accelerations of R = 2–20, as well as in carotids of 7 healthy subjects (27 ± 2 years, 4 male) for R = 10–30. Fully sampled 2D flow CMR served as a flow reference. Arteries were manually segmented and registered to enable voxel-wise comparisons of both velocity and WSS using a Bland-Altman analysis.ResultsMagnitude images, velocity images, and pathline reconstructions from phantom and in vivo scans were similar for all accelerations. For the phantom data, mean differences at peak systole for the entire vessel volume in comparison to R = 2 ranged from − 2.3 to − 5.3% (WSS) and − 2.4 to − 2.2% (velocity) for acceleration factors R = 4–20. For the in vivo data, mean differences for the entire vessel volume at peak systole in comparison to R = 10 were − 9.9, − 13.4, and − 16.9% (WSS) and − 8.4, − 10.8, and − 14.0% (velocity), for R = 20, 25, and 30, respectively. Compared to single slice 2D flow CMR acquisitions, peak systolic flow rates of the phantom showed no differences, whereas peak systolic flow rates in the carotid artery in vivo became increasingly underestimated with increasing acceleration.ConclusionAcquisition of 4D flow CMR of the carotid arteries can be highly accelerated by pseudo-spiral k-space sampling and compressed sensing reconstruction, with consistent data quality facilitating velocity pathline reconstructions, as well as quantitative flow rate and WSS estimations. At an acceleration factor of R = 20 the underestimation of peak velocity and peak WSS was acceptable (< 10%) in comparison to an R = 10 accelerated 4D flow CMR reference scan. Peak flow rates were underestimated in comparison with 2D flow CMR and decreased systematically with higher acceleration factors.

Comparison of cardiac output measured by carotid artery Doppler ultrasound and echocardiography in patients admitted to Golestan and Imam Khomeyni Hospitalsl in Ahvaz.

Introduction:Ultrasound is highly effective, safe, and cost-effective for monitoring the hemodynamics and measuring the cardiac output of patients. This study aims to investigate the value of cardiac output by the measurement of common carotid artery flow, which is an inexpensive, simple, and accessible method.Method:Doppler ultrasound of the carotid artery at thyroid level was obtained from the patients admitted to Golestan and Imam Khomeyni Hospitals in Ahvaz (the result is recorded medially from the bilateral outputs unless otherwise prescribed on one side due to a problem such as a catheter or specific position). A transthoracic echocardiography was also recorded using a portable device to measure the left ventricular outlet of diameter 0.5 cm below the aortic valve in the left parasternal with a long axis view.Results:Of the 94 patients studied between the ages of 25 to 87 years, 53 (56.4%) were males and 41 (43.6%) females with a mean age of 53.61 with a standard deviation of 14.56. There was a direct and significant relationship between age and cardiac output using both echocardiography and color Doppler carotid ultrasound (P < 0.001).Discussion:The results of this study showed that the measurement of cardiac output using color Doppler ultrasound in the case of inaccessible emergency echocardiography is a cheap, simple, and accessible method for the hemodynamic evaluation of patients.

Evaluation of common carotid and vertebral arteries flow volumes in patients with ankylosing spondylitis

Evaluation of common carotid and vertebral arteries flow volumes in patients with ankylosing spondylitis