Cerebral blood flow dynamics during cardiac surgery in infants

BACKGROUND

In this pilot study, we investigated continuous cerebral blood flow velocity measurements to explore cerebrovascular hemodynamics in infants with congenital heart disease undergoing cardiac surgery.

METHODS

A non-invasive transfontanellar cerebral Doppler monitor (NeoDoppler) was used to monitor 15 infants (aged eight days to nine months) during cardiac surgery with cardiopulmonary bypass. Numerical and visual analyses were conducted to assess trends and events in Doppler measurements together with standard monitoring equipment. The mean flow index, calculated as the moving Pearson correlation between mean arterial pressure and time averaged velocity, was utilized to evaluate dynamic autoregulation. Two levels of impaired autoregulation were defined (Mean flow index >0.3/0.45), and percentage of time above these limits were calculated.

RESULTS

High quality recordings were achieved during 90.6% of the monitoring period. There was a significant reduction in time averaged velocity in all periods of cardiopulmonary bypass. All patients showed a high percentage of time with impaired dynamic autoregulation, with Mean flow index >0.3 and 0.45: 73.71% ± 9.06% and 65.16% ± 11.27% respectively. Additionally, the system promptly detected hemodynamic events.

CONCLUSION

Continuous transfontanellar cerebral Doppler monitoring could become an additional tool in enhancing cerebral monitoring in infants during cardiac surgery.

IMPACT

This pilot study demonstrates the feasibility of continuous transfontanellar Doppler monitoring of cerebral blood flow velocities during cardiac surgery in infants. It also demonstrates a high proportion of time with impaired cerebral autoregulation during cardiac surgery based on the Mean flow index. Continuous transfontanellar Doppler could become a useful tool to improve cerebral monitoring and provide new pathophysiological insight.

Femoral Nailing in a Porcine Model Causes Bone Marrow Emboli in the Lungs and Systemic Emboli in the Heart and Brain

Background

Shaft fractures of the femur are commonly treated with intramedullary nailing, which can release bone marrow emboli into the bloodstream. Emboli can travel to the lungs, impairing gas exchange and causing inflammation. Occasionally, emboli traverse from the pulmonary to the systemic circulation, hindering perfusion and resulting in injuries such as heart and brain infarctions, known as fat embolism syndrome. We studied the extent of systemic bone marrow embolization in a pig model.

Methods

Twelve anesthetized pigs underwent bilateral intramedullary nailing of the femur, while 3 animals served as sham controls. Monitoring included transesophageal echocardiography (TEE), pulse oximetry, electrocardiography, arterial blood pressure measurement, and blood gas and troponin-I analysis. After surgery, animals were monitored for 240 minutes before euthanasia. Post mortem, the heart, lungs, and brain were biopsied.

Results

Bone marrow emboli were found in the heart and lungs of all 12 of the pigs that underwent intramedullary nailing and in the brains of 11 of them. No emboli were found in the sham group. The pigs subjected to intramedullary nailing exhibited significant hypoxia (PaO2/FiO2 ratio, 410 mm Hg [95% confidence interval (CI), 310 to 510) compared with the sham group (594 mm Hg [95% CI, 528 to 660]). The nailing group exhibited ST-segment alterations consistent with myocardial ischemia and a significant increase in the troponin-I level compared with the sham group (1,580 ng/L [95% CI, 0 to 3,456] versus 241 ng/L [95% CI, 0 to 625] at the 240-minute time point; p = 0.005). TEE detected emboli in the right ventricular outflow tract, but not systemically, in the nailing group.

Conclusions

Bilateral intramedullary nailing caused bone marrow emboli in the lungs and systemic emboli in the heart and brain in this pig model. The observed clinical manifestations were consistent with coronary and pulmonary emboli. TEE detected pulmonary but not systemic embolization.

Clinical Relevance

Femoral intramedullary nailing in humans is likely to result in embolization as described in our pig model. Focused monitoring is necessary for detection of fat embolism syndrome. Absence of visual emboli in the left ventricle on TEE does not exclude the occurrence of systemic bone marrow emboli.

Flow Dynamics in Children With Bicuspid Aortic Valve: A Blood Speckle Tracking Study

OBJECTIVE

Bicuspid aortic valve (BAV) is associated with progressive aortic dilation. Although the etiology is complex, altered flow dynamics is thought to play an important role. Blood speckle tracking (BST) allows for visualization and quantification of complex flow, which could be useful in identifying patients at risk of root dilation and could aid in surgical planning. The aims of this study were to assess and quantify flow in the aortic root and left ventricle using BST in children with bicuspid aortic valves.

METHODS AND RESULTS

A total of 38 children <10 y of age were included (24 controls, 14 with BAV). Flow dynamics were examined using BST in the aortic root and left ventricle. Children with BAV had altered systolic flow patterns in the aortic root and higher aortic root average vorticity (25.9 [23.4-29.2] Hz vs. 17.8 [9.0-26.2] Hz, p < 0.05), vector complexity (0.17 [0.14-0.31] vs. 0.05 [0.02-0.13], p < 0.01) and rate of energy loss (7.9 [4.9-12.1] mW/m vs. 2.7 [1.2-7.4] mW/m, p = 0.01). Left ventricular average diastolic vorticity (20.9 ± 5.8 Hz vs. 11.4 ± 5.2 Hz, p < 0.01), kinetic energy (0.11 ± 0.05 J/m vs. 0.04 ± 0.02 J/m, p < 0.01), vector complexity (0.38 ± 0.1 vs. 0.23 ± 0.1, p < 0.01) and rate of energy loss (11.1 ± 4.8 mW/m vs. 2.7 ± 1.9 mW/m, p < 0.01) were higher in children with BAV.

CONCLUSION

Children with BAV exhibit altered flow dynamics in the aortic root and left ventricle in the absence of significant aortic root dilation. This may represent a substrate and potential predictor for future dilation and diastolic dysfunction.

Randomised controlled trial of preconception lifestyle intervention on maternal and offspring health in people with increased risk of gestational diabetes: study protocol for the BEFORE THE BEGINNING trial

INTRODUCTION

Gestational diabetes mellitus (GDM) is associated with increased risk for type 2 diabetes in the mother and cardiometabolic diseases in the child. The preconception period is an optimal window to adapt the lifestyle for improved outcomes for both mother and child. Our aim is to determine the effect of a lifestyle intervention, initiated before and continued throughout pregnancy, on maternal glucose tolerance and other maternal and infant cardiometabolic outcomes.

METHODS AND ANALYSIS

This ongoing randomised controlled trial has included 167 females aged 18-39 years old at increased risk for GDM who are contemplating pregnancy. The participants were randomly allocated 1:1 to an intervention or control group. The intervention consists of exercise (volume is set by a heart rate-based app and corresponds to ≥ 1 hour of weekly exercise at ≥ 80% of individual heart rate maximum), and time-restricted eating (≤ 10 hours/day window of energy intake). The primary outcome measure is glucose tolerance in gestational week 28. Maternal and offspring outcomes are measured before and during pregnancy, at delivery, and at 6-8 weeks post partum. Primary and secondary continuous outcome measures will be compared between groups based on the 'intention to treat' principle using linear mixed models.

ETHICS AND DISSEMINATION

The Regional Committees for Medical and Health Research Ethics in Norway has approved the study (REK 143756). The anonymised results will be submitted for publication and posted in a publicly accessible database of clinical study results.

TRIAL REGISTRATION NUMBER

Clinical trial gov NCT04585581.

Continuous monitoring of cerebral blood flow during general anaesthesia in infants

Background

General anaesthesia is associated with neurocognitive deficits in infants after noncardiac surgery. Disturbances in cerebral perfusion as a result of systemic hypotension and impaired autoregulation may be a potential cause. Our aim was to study cerebral blood flow (CBF) velocity continuously during general anaesthesia in infants undergoing noncardiac surgery and compare variations in CBF velocity with simultaneously measured near-infrared spectroscopy (NIRS), blood pressure, and heart rate.

Methods

NeoDoppler, a recently developed ultrasound system, was used to monitor CBF velocity via the anterior fontanelle during induction and maintenance of general anaesthesia until the start of surgery, and during recovery. NIRS, blood pressure, and heart rate were monitored simultaneously and synchronised with the NeoDoppler measurements.

Results

Thirty infants, with a median postmenstrual age at surgery of 37.6 weeks (range 28.6-60.0) were included. Compared with baseline, the trend curves showed a decrease in CBF velocity during induction and maintenance of anaesthesia and returned to baseline values during recovery. End-diastolic velocity decreased in all infants during anaesthesia, on average by 59%, whereas peak systolic- and time-averaged velocities decreased by 26% and 45%, respectively. In comparison, the reduction in mean arterial pressure was only 20%. NIRS values were high and remained stable. When adjusting for mean arterial pressure, the significant decrease in end-diastolic velocity persisted, whereas there was only a small reduction in peak systolic velocity.

Conclusions

Continuous monitoring of CBF velocity using NeoDoppler during anaesthesia is feasible and may provide valuable information about cerebral perfusion contributing to a more targeted haemodynamic management in anaesthetised infants.

Continuous fetal cerebral blood flow monitoring during labor: A feasibility study

BACKGROUND

Current methods for fetal surveillance during labor have significant limitations. Since continuous fetal cerebral blood flow velocity (CBFV) monitoring during labor may add valuable information about fetal well-being, we developed a new ultrasound system called VisiBeam. VisiBeam consists of a flat probe (diameter 11 mm) with a cylindric plane wave beam, a vacuum attachment (diameter 40 mm), a scanner, and a display.

AIMS

To assess the feasibility of VisiBeam for continuous fetal CBFV monitoring during labor, and to study changes in CBFV during uterine contractions.

STUDY DESIGN

Descriptive observational study.

SUBJECTS

Twenty-five healthy women in labor with a singleton fetus in cephalic presentation at term. A transducer was placed over a fontanelle and attached to the fetal head with vacuum suction.

OUTCOME MEASURES

Achievement of continuous good quality fetal CBFV measures, such as peak systolic velocity, time averaged maximum velocity and end diastolic velocity. Trend plots of velocity measures display changes in CBFV between and during uterine contractions.

RESULTS

Good quality recordings during and between contractions were achieved in 16/25 fetuses. In twelve fetuses, CBFV measures were stable during uterine contractions. Four fetuses showed patterns of reduced CBFV velocity measures during contractions.

CONCLUSIONS

Continuous fetal CBFV monitoring by VisiBeam was feasible in 64 % of the subjects during labor. The system displayed variations of fetal CBFV not available by today's monitoring techniques and motivates for further studies. However, improvement of the probe attachment is required to ensure good quality signal in a higher proportion of fetuses during labor.

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

Assessment of Early Diastolic Intraventricular Pressure Difference in Children by Blood Speckle-Tracking Echocardiography

BACKGROUND

The lack of reliable echocardiographic techniques to assess diastolic function in children is a major clinical limitation. Our aim was to develop and validate the intraventricular pressure difference (IVPD) calculation using blood speckle-tracking (BST) and investigate the method's potential role in the assessment of diastolic function in children.

METHODS

Blood speckle-tracking allows two-dimensional angle-independent blood flow velocity estimation. Blood speckle-tracking images of left ventricular (LV) inflow from the apical 4-chamber view in 138 controls, 10 patients with dilated cardiomyopathies (DCMs), and 21 patients with hypertrophic cardiomyopathies (HCMs) <18 years of age were analyzed to study LV IVPD during early diastole. Reproducibility of the IVPD analysis was assessed, IVPD estimates from BST and color M mode were compared, and the validity of the BST-based IVPD calculations was tested in a computer flow model.

RESULTS

Mean IVPD was significantly higher in controls (-2.28 ± 0.62 mm Hg) compared with in DCM (-1.21 ± 0.39 mm Hg, P < .001) and HCM (-1.57 ± 0.47 mm Hg, P < .001) patients. Feasibility was 88.3% in controls, 80% in DCM patients, and 90.4% in HCM patients. The peak relative negative pressure occurred earlier at the apex than at the base and preceded the peak E-wave LV filling velocity, indicating that it represents diastolic suction. Intraclass correlation coefficients for intra- and interobserver variability were 0.908 and 0.702, respectively. There was a nonsignificant mean difference of 0.15 mm Hg between IVPD from BST and color M mode. Estimation from two-dimensional velocities revealed a difference in peak IVPD of 0.12 mm Hg (6.6%) when simulated in a three-dimensional fluid mechanics model.

CONCLUSIONS

Intraventricular pressure difference calculation from BST is highly feasible and provides information on diastolic suction and early filling in children with heart disease. Intraventricular pressure difference was significantly reduced in children with DCM and HCM compared with controls, indicating reduced early diastolic suction in these patient groups.

Pulmonary Hypertension in Children is Associated With Abnormal Flow Patterns in the Main Pulmonary Artery as Demonstrated by Blood Speckle Tracking

Background

Paediatric pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance resulting in increased pulmonary artery (PA) and right ventricular pressure (RV). This is associated with disturbed flow dynamics in the PA and RV that are not well characterized. We aimed to compare flow dynamics in children with PAH compared with healthy controls using blood speckle tracking echocardiography.

Methods

Patients <10 years of age with PAH and healthy controls were included. We examined flow dynamics in the main PA (MPA) and right ventricle based on acquisition blood speckle tracking images obtained from the RV and PA. Qualitative and quantitative analyses were performed.

Results

Eighteen subjects were included in each group. A diastolic vortex in the MPA was identified in 16 of the patients with PAH, but not in controls. Significantly higher MPA systolic (4.84 vs 2.42 mW/m; P = 0.01) and diastolic (0.69 vs 0.14 mW/m; P = 0.01) energy loss, as well as increased vector complexity (systole: 0.21 vs 0.04, P = 0.003; diastole: 0.13 vs 0.05, P = 0.04) and diastolic vorticity (15.2 vs 4.4 Hz; P = 0.001), were noted in PAH compared with controls.

Conclusion

This study demonstrates the presence of abnormal flow patterns in the MPA with diastolic vortex formation in most patients with PAH. This diastolic vortex likely results from reflected waves from the distal pulmonary bed. Our data indicate that the diastolic vortex could potentially be used in the diagnosis of PAH. The clinical significance of the energy loss findings warrants further investigation in a larger cohort of patients with PAH.

Detection of Cerebral High-Intensity Transient Signals by NeoDoppler during Cardiac Catheterization and Cardiac Surgery in Infants

There is a risk of gaseous and solid micro-embolus formation during transcatheter cardiac interventions and surgery in children with congenital heart disease (CHD). Our aim was to study the burden of high-intensity transient signals (HITS) during these procedures in infants. We used a novel color M-mode Doppler (CMD) technique by NeoDoppler, a non-invasive ultrasound system based on plane wave transmissions for transfontanellar continuous monitoring of cerebral blood flow in infants. The system displays CMD with 24 sample volumes and a Doppler spectrogram. Infants with CHD undergoing transcatheter interventions (n = 15) and surgery (n = 13) were included. HITS were manually detected based on an "embolic signature" in the CMD with corresponding intensity increase in the Doppler spectrogram. Embolus-to-blood ratio (EBR) defined HITS size. A total of 1169 HITS with a median EBR of 9.74 dB (interquartile range [IQR]: 5.10-15.80 dB) were detected. The median number of HITS in the surgery group was 45 (IQR: 11-150), while in the transcatheter group the median number was 12 (IQR: 7-24). During cardiac surgery, the highest number of HITS per hour was seen from initiation of cardiopulmonary bypass to aortic X-clamp. In this study we detected frequent HITS and determined the feasibility of using NeoDoppler monitoring for HITS detection.

Low frequency cerebral arterial and venous flow oscillations in healthy neonates measured by NeoDoppler

BACKGROUND

A cerebroprotective effect of low frequency oscillations (LFO) in cerebral blood flow (CBF) has been suggested in adults, but its significance in neonates is not known. This observational study evaluates normal arterial and venous cerebral blood flow in healthy neonates using NeoDoppler, a novel Doppler ultrasound system which can measure cerebral hemodynamics continuously.

METHOD

Ultrasound Doppler data was collected for 2 h on the first and second day of life in 36 healthy term born neonates. LFO (0.04-0.15 Hz) were extracted from the velocity curve by a bandpass filter. An angle independent LFO index was calculated as the coefficient of variation of the filtered curve. Separate analyses were done for arterial and venous signals, and results were related to postnatal age and behavioral state (asleep or awake).

RESULTS

The paper describes normal physiologic variations of arterial and venous cerebral hemodynamics. Mean (SD) arterial and venous LFO indices (%) were 6.52 (2.55) and 3.91 (2.54) on day one, and 5.60 (1.86) and 3.32 (2.03) on day two. After adjusting for possible confounding factors, the arterial LFO index was estimated to decrease by 0.92 percent points per postnatal day (p < 0.001). The venous LFO index did not change significantly with postnatal age (p = 0.539). Arterial and venous LFO were not notably influenced by behavioral state.

CONCLUSION

The results indicate that arterial LFO decrease during the first 2 days of life in healthy neonates. This decrease most likely represents normal physiological changes related to the transitional period. A similar decrease for venous LFO was not found.

Right Ventricular Flow Dynamics in Dilated Right Ventricles: Energy Loss Estimation Based on Blood Speckle Tracking Echocardiography-A Pilot Study in Children

Using blood speckle tracking (BST) based on high-frame-rate echocardiography (HFRE), we compared right ventricle (RV) flow dynamics in children with atrial septal defects (ASDs) and repaired tetralogy of Fallot (rTOF). Fifty-seven children with rTOF with severe pulmonary insufficiency (PI) (n = 21), large ASDs (n = 11) and healthy controls (CTL, n = 25) were included. Using a flow phantom, we studied the effects of imaging plane and smoothing parameters on 2-D energy loss (EL). RV diastolic EL was similar in ASD and rTOF, but both were greater than in CTL. Locations of high EL were similar in all groups in systole, occurring in the RV outflow tract and around the tricuspid valve leaflets in early diastole. An additional apical early diastolic area of EL was noted in rTOF, corresponding to colliding tricuspid inflow and PI. The flow phantom revealed that EL varied with imaging plane and smoothing settings but that the EL trend was preserved if kept consistent.

Monitoring of cerebral high intensity transient signals during catheter interventions and surgery for congenital heart disease in infants using NeoDoppler

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Joint Research Committee between St. Olavs Hospital and the faculty of Medicine, NTNU. The Norwegian Association for Children with Congenital Heart Disease Research Foundation, FFHB

Background

 

There is a risk of gaseous- and solid micro embolus formation during transcatheter procedures (CATH) and surgery in children with congenital heart disease (CHD). Silent strokes during surgery or CATH may contribute to neurological impairment. NeoDoppler is a non-invasive ultrasound system based on plane wave transmissions to continuously monitor cerebral blood flow in infants with an open fontanelle. Gaseous- and solid micro embolus passing through the ultrasound beam create High Intensity Transient Signals (HITS) in the Doppler signal. 

Purpose

We aimed to study the amount of HITS during CATH and surgery in infants using NeoDoppler. 

Methods

 

The NeoDoppler probe operates at a frequency of 7.8 MHz. The frame rate is 300 fps and the beam covers a wide cylindrical area (10/35mm width/depth). The system displays a color M-mode Doppler and a spectrogram. The broad ultrasound beam permits prolonged scanning time of each event as the HITS move through the ultrasound beam. The high framerate and color M-mode allows for tracking of embolies in depth.

In this study the NeoDoppler probe was attached to the anterior fontanelle of infants with CHD during CATH (n = 15) and cardiac surgery (n = 13). HITS were defined as high intensity signal creating skewed lines in the color M-mode Doppler moving away or towards the probe (blue/red) with a corresponding high intensity signal in the spectrogram. HITS were grouped into single HITS and HITS with curtain effect. Single HITS were defined as single skewed lines in the color M-mode Doppler and spectrogram. HITS with curtain effect were defined as skewed broad lines or multiple intensity increase lines in the color M-mode Doppler with corresponding intensity increase that filled the entire doppler curve. HITS with curtain effect are believed to represent numerous HITS that could not be separated from each other in the spectrogram. HITS were manually detected in an in-house MatLab application.

Results

 

The study group consisted of 28 infants (17 males) with different CHD who underwent CATH or surgery. The median age and weight was 96 days (range 3-240 days) and 5650 g (range 2400-8085 g). HITS were detected in 13/15 patients during CATH with a total of 392 HITS (Median 12, Range 0-149) and in all patients during surgery with a total of 772 HITS (Median 45, Range 11-150). 

The picture shows examples of single HITS (panel A) and HITS with curtain effect (panel B). One can appreciate the embolic trajectory pattern in depth over time in the color M-mode Display. 

Conclusion

 

In this study we found that NeoDoppler enables detection of frequent HITS in patients with CHD undergoing surgery or CATH. NeoDoppler could become a useful tool to guide modifications of procedures, with aim to reduce the risk of silent stroke. However, further studies are needed to validate the technique.

Abstract Figure.

Live born recipient of twin-twin transfusion syndrome with anomalous mitral arcade

We present a case report of anomalous mitral arcade in a live born former recipient of twin–twin transfusion syndrome. At 33+0 week of gestation fetal ultrasound demonstrated that she had a large mitral insufficiency, decreased movement of the lateral cusp of the mitral valve and dilated left atrium. The twins were delivered by caesarean section at week 33+1 due to fetal distress. The former recipient twin developed decompensated heart failure during her first day of life and was transferred to a surgical paediatric heart centre. Her clinical condition rapidly deteriorated, and she died of congestive heart failure 3 days old. Prenatal signs of anomalous mitral arcade in a recipient of twin–twin transfusion syndrome should warrant preparation of a critically ill neonate, including parental counselling and in utero transfer to surgical paediatric heart centre. There is a surgical treatment option available for neonates, but the experience with this technique is still very limited with a high risk of morbidity and mortality.

Cardiac function in newborns of obese women and the effect of exercise during pregnancy. A randomized controlled trial

Background

The prevalence of maternal obesity is rising. Pre-pregnancy obesity is associated with later cardiovascular disease in the child and the underlying pathogenesis begins in early life. Therefore, pregnancy and infancy are key periods for potential intervention. The aim of this study was to study the cardiac function in newborns of obese women compared to newborns of normal-weight women, and to determine if exercise intervention during pregnancy could have an effect on cardiac function of newborns to obese women.

Material and methods

Fifty-five pregnant women, 51 obese (BMI ≥ 30 kg/m²) and four overweight (BMI 28–30 kg/m²), were randomized to an exercise training group (n = 27) or a control group (standard maternity care, n = 28). From gestational week 14 until delivery participants in the intervention group were offered supervised training sessions three times weekly. In addition, they were told to exercise at home once weekly. All newborns had an echocardiogram performed 1–3 days and 6–8 weeks after delivery. The results were compared with newborns of normal weight women (n = 20, standard maternity care).

Results

Newborns of obese women had an impaired systolic and diastolic cardiac function with reduced global strain, strain rate, tissue Doppler velocities and a thicker intraventricular septum at birth and after 6–8 weeks after delivery compared to newborns of normal weight women. Exercise had no statistically significant effect on either of the cardiac function parameters. The mean (± standard deviation) adherence to the exercise protocol was 1.3 ± 0.8 sessions per week for supervised training and 0.8 ± 0.7 sessions per week for home-based exercise training.

Conclusions

Newborns of obese women had reduced cardiac function and thicker intraventricular septum compared to newborns of normal weight women. Exercise training during pregnancy had no significant effect, potentially due to a low number of subjects and low adherence to the exercise protocol.

Trial registration

ClinicalTrials.gov NCT01243554.

In Vivo Intracardiac Vector Flow Imaging Using Phased Array Transducers for Pediatric Cardiology

Two-dimensional blood speckle tracking (ST) has shown promise for measuring complex flow patterns in neonatal hearts using linear arrays and high-frame-rate plane wave imaging. For general pediatric applications, however, the need for phased array probes emerges due to the limited intercostal acoustic window available. In this paper, a clinically approved real-time duplex imaging setup with phased array probes was used to investigate the potential of blood ST for the 2-D vector flow imaging of children with congenital heart disease. To investigate transmit beam pattern and tracking accuracy, straight tubes with parabolic flow were simulated at three depths (4.5, 7, and 9.5 cm). Due to the small aperture available, diffraction effects could be observed when approaching 10 cm, which limited the number of parallel receive beams that could be utilized. Moving to (slightly) diverging beams was shown to solve this issue at the expense of a loss in signal-to-noise ratio. To achieve consistent estimates, a forward-backward tracking scheme was introduced to avoid measurement bias occurring due to tracking kernel averaging artifacts at flow domain boundaries. Promising results were observed for depths <10 cm in two pediatric patients, where complex cardiac flow patterns could be estimated and visualized. As a loss in penetration compared with color flow imaging is expected, a larger clinical study is needed to establish the clinical feasibility of this approach.

Effect of supervised exercise training during pregnancy on neonatal and maternal outcomes among overweight and obese women. Secondary analyses of the ETIP trial: A randomised controlled trial

Background

Maternal obesity associates with complications during pregnancy and childbirth. Our aim was to investigate if exercise during pregnancy in overweight/obese women could influence birth weight or other neonatal and maternal outcomes at delivery.

Material and methods

This is a secondary analysis of a randomised controlled trial of exercise training in pregnancy for women with body mass index (BMI) ≥ 28 kg/m². Ninety-one women (31.3 ± 4.3 years, BMI 34.5 ± 4.2 kg/m²) were allocated 1:1 to supervised exercise during pregnancy or to standard care. The exercise group was offered three weekly training sessions consisting of 35 minutes of moderate intensity walking/running followed by 25 minutes of strength training. Data from 74 women (exercise 38, control 36) were analysed at delivery.

Results

Birth weight was 3719 ± 695 g in the exercise group and 3912 ± 413 g in the control group (CI -460.96, 74.89, p = 0.16). Birth weight > 4000 g was 35% in the exercise group and 52% in the control group (p = 0.16). Mean gestational age at delivery was 39.1 weeks in the exercise group and 39.5 weeks in the control group (CI -1.33, 0.43, p = 0.31). No significant between-group differences were found in neonatal body size, skinfold thickness, placental weight ratio, or Apgar score. The prevalence of caesarean section was 24% in the exercise group and 17% in the control group (CI 0.20, 2.05, p = 0.57). Mean length of hospital stay was 4.8 days in the exercise group and 4.5 days in the control group (CI -0.45, 1.00, p = 0.45).

Conclusions

Offering supervised exercise during pregnancy for overweight and obese women did not influence birth weight or other neonatal and maternal outcomes at delivery. However our trial was limited by low sample size and poor adherence to the exercise protocol, and further research is needed.

Trial registration

ClinicalTrials.gov NCT01243554

Prenatal constriction of the ductus arteriosus following maternal diclofenac medication in the third trimester

We describe a case of a 21-year-old primigravida at 36 weeks' gestation who was admitted to a local hospital because of abdominal pain. She was prescribed a total of six doses of diclofenac 50 mg over 2 days. One day later, there was difficulty registering the fetal heartbeats on cardiotocography. Ultrasound examination revealed a fetus with ascites and pathological flow over the tricuspid valve. The patient was referred to a tertiary centre for fetal medicine. Fetal echocardiography revealed, in addition to ascites and tricuspid regurgitation, a constricted ductus arteriosus, dilated right ventricle and reduced flow in the pulmonary artery. Immediate caesarean section resulted in an excellent neonatal outcome.

Robust angle-independent blood velocity estimation based on dual-angle plane wave imaging

Two-dimensional blood velocity estimation has shown potential to solve the angle-dependency of conventional ultrasound flow imaging. Clutter filtering, however, remains a major challenge for large beam-to-flow angles, leading to signal drop-outs and corrupted velocity estimates. This work presents and evaluates a compounding speckle tracking (ST) algorithm to obtain robust angle-independent 2-D blood velocity estimates for all beam-to-flow angles. A dual-angle plane wave imaging setup with full parallel receive beamforming is utilized to achieve high-frame-rate speckle tracking estimates from two scan angles, which may be compounded to obtain velocity estimates of increased robustness. The acquisition also allows direct comparison with vector Doppler (VD) imaging. Absolute velocity bias and root-mean-square (RMS) error of the compounding ST estimations were investigated using simulations of a rotating flow phantom with low velocities ranging from 0 to 20 cm/s. In a challenging region where the estimates were influenced by clutter filtering, the bias and RMS error for the compounding ST estimates were 11% and 2 cm/s, a significant reduction compared with conventional single-angle ST (22% and 4 cm/s) and VD (36% and 6 cm/s). The method was also tested in vivo for vascular and neonatal cardiac imaging. In a carotid artery bifurcation, the obtained blood velocity estimates showed that the compounded ST method was less influenced by clutter filtering than conventional ST and VD methods. In the cardiac case, it was observed that ST velocity estimation is more affected by low signal-to-noise (SNR) than VD. However, with sufficient SNR the in vivo results indicated that a more robust angle-independent blood velocity estimator is obtained using compounded speckle tracking compared with conventional ST and VD methods.

Shunt flow evaluation in congenital heart disease based on two-dimensional speckle tracking

High-frame-rate ultrasound speckle tracking was used for quantification of peak velocity in shunt flows resulting from septal defects in congenital heart disease. In a duplex acquisition scheme implemented on a research scanner, unfocused transmit beams and full parallel receive beamforming were used to achieve a frame rate of 107 frames/s for full field-of-view flow images with high accuracy, while also ensuring high-quality focused B-mode tissue imaging. The setup was evaluated in vivo for neonates with atrial and ventricular septal defects. The shunt position was automatically tracked in B-mode images and further used in blood speckle tracking to obtain calibrated shunt flow velocities throughout the cardiac cycle. Validation toward color flow imaging and pulsed wave Doppler with manual angle correction indicated that blood speckle tracking could provide accurate estimates of shunt flow velocities. The approach was less biased by clutter filtering compared with color flow imaging and was able to provide velocity estimates beyond the Nyquist range. Possible placements of sample volumes (and angle corrections) for conventional Doppler resulted in a peak shunt velocity variations of 0.49-0.56 m/s for the ventricular septal defect of patient 1 and 0.38-0.58 m/s for the atrial septal defect of patient 2. In comparison, the peak velocities found from speckle tracking were 0.77 and 0.33 m/s for patients 1 and 2, respectively. Results indicated that complex intraventricular flow velocity patterns could be quantified using high-frame-rate speckle tracking of both blood and tissue movement. This could potentially help increase diagnostic accuracy and decrease inter-observer variability when measuring peak velocity in shunt flows.

Blood Flow Imaging?A New Angle-Independent Ultrasound Modality for the Visualization of Flow in Atrial Septal Defects in Children

BACKGROUND

Color Doppler imaging (CDI) is the most applied method for evaluation of flow in atrial septal defects (ASD). A new real time ultrasound flow imaging modality called blood flow imaging (BFI) is able to visualize the blood flow in any direction of the image and is not limited by velocity aliasing. The method thereby overcomes the two limitations most often encountered in CDI. In this study we compared BFI with CDI for the visualization of interatrial blood flow in children.

METHODS

We studied ASD flow in 13 children using both CDI and BFI in the same examination. CDI and BFI cineloops were prepared off-line and both optimal and suboptimal (increased color artifacts) images were presented in random order to four observers. They were asked to range from 0-100 on a visual analogue scale how certain they were of interatrial blood flow. The CDI and BFI ratings were compared using the exact Wilcoxon signed rank test for paired samples.

RESULTS

All ASDs visualized with CDI were confirmed using BFI. Two of the observers ranked BFI as being significantly better than CDI when the images were optimized. When the images were suboptimal three of the observers rated BFI as being significantly better.

CONCLUSIONS

This pilot study indicates that BFI improves the visualization of interatrial blood flow in children. To include BFI in the ordinary echocardiography examination is easy and not time consuming. The method may prove to be a useful supplement to CDI in ASD imaging.