The novel and slowest arterial pressure waves: clinical implications in children with congenital heart disease following cardiovascular surgery.

OBJECTIVES: Certain rhythmic arterial pressure waves in humans and animals have been noticed for over one century. We found the novel and slowest arterial pressure waves in children following surgical repair for CHD, and examined their characteristics and clinical implications. METHODS: We enrolled 212 children with 22 types of CHD within postoperative 48 h. We monitored haemodynamics (blood pressure, cardiac cycle efficiency, dP/dTmax), cerebral (ScO2), and renal (SrO2) oxygen saturation every 6 s. Electroencephalogram was continuously monitored. Mean blood flow velocity (Vm) of the middle cerebral artery was measured at 24 h. RESULTS: We found the waves with a frequency of ∼ 90 s immediately following surgical repair in 46 patients in 12 types of CHD (21.7%), being most prevalent in patients with aortic arch abnormalities (Aorta Group, n = 24, 42.3%) or ventricular septal defect (Ventricular Septal Defect Group, n = 12, 23.5%). In Aorta and Ventricular Septal Defect Groups, the occurrence of the waves was associated with lower blood pressures, dP/dTmax, cardiac cycle efficiency, ScO2, SrO2, Vm, worse electroencephalogram background abnormalities, higher number of electroencephalogram sharp waves, and serum lactate (Ps <0.0001-0.07), and were accompanied with fluctuations of ScO2 and SrO2 in 80.6% and 69.6% of patients, respectively. CONCLUSIONS: The waves observed in children following cardiovascular surgery are the slowest ever reported, occurring most frequently in patients with aortic arch abnormalities or ventricular septal defect. While the occurrence of the waves was associated with statistically worse and fluctuated ScO2 and SrO2, worse systemic haemodynamics, and electroencephalogram abnormalities, at present these waves have no known clinical relevance.

Haemodynamic significance of extrinsic outflow graft stenoses during HeartMate 3™ therapy.

Aims: The HeartMate 3 (HM3) implantable left ventricular assist device connects the left ventricle apex to the aorta via an outflow graft. Extrinsic obstruction of the graft (eOGO) is associated with serious morbidity and mortality and recently led to a Food and Drug Administration Class 1 device recall of HM3. This study aimed to provide a better understanding of the haemodynamic impact of extrinsic stenoses. Methods and results: Computed tomography (CT) images of two retrospectively identified patients with eOGO (29 and 36% decrease in cross-sectional area, respectively, by radiological evaluation) were acquired with a novel photon-counting CT system. Numerical evaluations of haemodynamics were conducted using a high-fidelity 3D computational fluid dynamics approach on both the patient-specific graft geometries and in two virtually augmented stenotic severities and three device flows. Visual analysis identified increased velocity, pressure, and turbulent flow in the outer anterior curvature of the outflow graft; however, changes in graft pressure gradients were slight (1-9 mmHg) across the range of stenosis severities and flow rates tested. Conclusion: Evidence of eOGO during HM3 support and the recent device recall can provoke clinical apprehension and interventions. The haemodynamic impact of a stenosis detected visually or by quantification of cross-sectional area reduction may be difficult to predict and easily overestimated. This numerical study suggests that, for clinically encountered flow rates and stenosis severities below 61% in cross-sectional area decrease, eOGO may have low haemodynamic impact. This suggests that patients without symptoms or signs consistent with haemodynamically significant obstruction might be managed expectantly.

Acute effects of exercise on macro- and microvasculature in individuals with type 1 diabetes - a secondary outcome analysis.

Background: Type 1 diabetes is a chronic autoimmune disease associated with insulin-producing beta cell destruction, declining insulin secretion, and elevated blood glucose. Physical activity improves glycaemic control and cardiovascular health. This study explores acute effects of maximal exhaustion induced by a cardiopulmonary exercise on macro- and microvascular parameters in type 1 diabetes. Methodology: Twenty-five participants with type 1 diabetes (14 males, 11 females), aged 41.4 ± 11.87 years, BMI 23.7 ± 3.08, completed a repeated-measure study. Measurements pre-, post-, 30- and 60-minutes post-exhaustion involved a maximal incremental cardio-pulmonary exercise test. Macro- and microvascular parameters were assessed using VICORDER® and retinal blood vessel image analysis. Repeated measures ANOVA in SPSS (Version 27.0) analysed data. Results: Post-exercise, heart rate increased (p<.001), and diastolic blood pressure decreased (p=.023). Diabetes duration correlated with pulse wave velocity (r=0.418, p=.047), diastolic blood pressure (r=0.470, p=.023), and central retinal arteriolar equivalent (r=0.492, p=.023). Conclusion: In type 1 diabetes, cardiopulmonary exercise-induced exhaustion elevates heart rate and reduces diastolic blood pressure. Future research should explore extended, rigorous physical activity protocols for greater cardiovascular risk reduction.

Haemodynamic effects of intra-aortic balloon pumps stratified by baseline pulmonary artery pulsatility index.

AIMS: Intra-aortic balloon pump (IABP) devices are commonly used in patients with heart failure related cardiogenic shock (HF-CS), including those with out-of-proportion right ventricular (RV) dysfunction. Pulmonary artery pulsatility index (PAPi) is a haemodynamic surrogate for RV performance. We aimed to assess short-term haemodynamic changes in patients with HF-CS following IABP support stratified by baseline PAPi. METHODS AND RESULTS: This is a single-centre study of 67 consecutive patients with HF-CS who underwent IABP placement between 2020 and 2022. The primary aim was haemodynamic changes of specific variables on pulmonary artery catheter monitoring over 72 h following IABP placement. Secondary aims were clinically significant changes in diuretic regimens, changes in inotropes or vasopressors at 72 h following IABP, along with clinical outcomes. Prior to IABP placement, 57% of the total cohort (median age 59 years [48, 69], 31% female) had Society of Cardiovascular Angiography and Interventions Stage C HF-CS. Thirty-eight (56%) patients had a PAPi <2.0. Following 72 h of IABP support, the PAPi <2.0 group had an observed significant decrease in central venous pressure (CVP; 20 to 12 mmHg, P < 0.001) and mean pulmonary artery pressure (mPAP; 37.5 to 28.5 mmHg, P = 0.001), and an increase in PAPi (1 to 1.6, P = 0.001). No significant change in cardiac index (CI; 2 to 2.1 L/min/m2, P = 0.31) was observed. The PAPi ≥2.0 group (N = 29) had no observed significant change in CVP (10 to 8 mmHg, P = 0.47), or PAPi (2.6 to 2.8, P = 0.92), but there was a significant improvement in CI (1.9 to 2.5 L/min/m2, P = 0.004) along with reduction in mPA (37 to 29 mmHg, P = 0.03). The PAPi <2.0 group had a significant increase in diuretic requirement (52.6% vs. 20.7%, P = 0.01) and numerically greater addition of inotropes/vasopressors (47.3% vs. 34.4%, P = 0.07) compared with the PAPi ≥2.0 group at 72 h following IABP placement. Significantly more patients in the PAPi ≥2.0 group underwent left ventricular assist device (55.2% vs. 26.3%, P = 0.02), with no overall significant differences observed in escalation to veno-arterial extracorporeal membrane oxygenation, 30-day mortality, renal replacement therapy post-IABP, or rates of heart transplantation. CONCLUSIONS: IABP devices in those with HF-CS and low or abnormal PAPi may provide modest short-term haemodynamic benefits without significant improvement in CI, along with greater need for adjustment in medical therapeutics to achieve haemodynamic optimization.

The relation between socioeconomic status and invasive haemodynamics at evaluation for advanced heart failure.

AIMS: Socioeconomic deprivation is a risk marker for worse prognosis in patients with heart failure (HF), and a potential barrier to referral for advanced HF evaluation. The relationship between socioeconomic status (SES) and invasive haemodynamics in patients undergoing evaluation for advanced HF therapies is unknown. METHODS: We combined a consecutive clinical registry of patients evaluated for advanced HF with patient-level data on SES (household income, education, workforce status, cohabitant status and distance from home to tertiary HF centre) derived from nationwide registries. Using this information, the cohort was divided into groups of low-, medium- and high degree of socioeconomic deprivation. The associations between SES and invasive haemodynamics were explored with multiple linear regression adjusted for age and sex. RESULTS: A total of 631 patients were included. The median age was 53 years, and 23% were women. Patients in the highest income quartile versus the lowest (Q4 vs. Q1) were older (median age 57 vs. 50 years) and more often male (83% vs. 67%), both P < 0.001. Increasing household income (per 100 000 Danish kroner,1 EUR = 7.4 DKK) was associated with lower pulmonary capillary wedge pressure (PCWP) [-0.18 mmHg, 95% confidence interval (CI) -0.36 to -0.01, P = 0.036] but not significantly associated with central venous pressure (CVP) (-0.07 mmHg, 95% CI -0.21 to 0.06, P = 0.27), cardiac index (-0.004 L/min/m2, 95% CI -0.02 to 0.01, P = 0.60), or pulmonary vascular resistance (PVR) (-0.003 Wood units, 95% CI -0.37 to 0.16, P = 0.84). Comparing the most deprived with the least deprived group, adjusted mean PVR was higher (0.35 Wood units, 95% CI 0.02 to 0.68, P = 0.04), but PCWP (0.66 mmHg, 95% CI -1.49 to 2.82, P = 0.55), CVP (-0.26 mmHg, 95% CI -1.76 to 1.24, P = 0.73) and cardiac index (-0.03 L/min/m2, 95% CI -0.22 to 0.17, P = 0.78) were similar. CONCLUSIONS: Most haemodynamic measurements were similar across layers of SES. Nevertheless, there were some indications of worse haemodynamics in patients with lower household income or a high accumulated burden of socioeconomic deprivation. Particular attention may be warranted in socioeconomically deprived patients to ensure timely referral for advanced HF evaluation.

Measurement of blood-brain barrier water exchange rate using diffusion-prepared and multi-echo arterial spin labelling: Comparison of quantitative values and age dependence.

Water exchange rate (Kw) across the blood-brain barrier (BBB) is an important physiological parameter that may provide new insight into ageing and neurodegenerative disease. Recently, two non-invasive arterial spin labelling (ASL) MRI methods have been developed to measure Kw, but results from the different methods have not been directly compared. Furthermore, the association of Kw with age for each method has not been investigated in a single cohort. Thirty participants (70% female, 63.8 ± 10.4 years) were scanned at 3 T with Diffusion-Prepared ASL (DP-ASL) and Multi-Echo ASL (ME-ASL) using previously implemented acquisition and analysis protocols. Grey matter Kw, cerebral blood flow (CBF) and arterial transit time (ATT) were extracted. CBF values were consistent; approximately 50 ml/min/100 g for both methods, and a strong positive correlation in CBF from both methods across participants (r = 0.82, p < 0.001). ATT was significantly different between methods (on average 147.7 ms lower when measured with DP-ASL compared to ME-ASL) but was positively correlated across participants (r = 0.39, p < 0.05). Significantly different Kw values of 106.6 ± 19.7 min-1 and 306.8 ± 71.7 min-1 were measured using DP-ASL and ME-ASL, respectively, and DP-ASL Kw and ME-ASL Kw were negatively correlated across participants (r = -0.46, p < 0.01). Kw measured using ME-ASL had a significant linear relationship with age (p < 0.05). In conclusion, DP-ASL and ME-ASL provided estimates of Kw with significantly different quantitative values and inconsistent dependence with age. We propose future standardisation of modelling and fitting methods for DP-ASL and ME-ASL, to evaluate the effect on Kw quantification. Also, sensitivity and bias analyses should be performed for both approaches, to assess the effect of varying acquisition and fitting parameters. Lastly, comparison with independent measures of BBB water transport, and with physiological and clinical biomarkers known to be associated with changes in BBB permeability, are essential to validate the ASL methods, and to demonstrate their clinical utility.

Reduced order modelling of intracranial aneurysm flow using proper orthogonal decomposition and neural networks.

Reduced order modelling (ROMs) methods, such as proper orthogonal decomposition (POD), systematically reduce the dimensionality of high-fidelity computational models and potentially achieve large gains in execution speed. Machine learning (ML) using neural networks has been used to overcome limitations of traditional ROM techniques when applied to nonlinear problems, which has led to the recent development of reduced order models augmented by machine learning (ML-ROMs). However, the performance of ML-ROMs is yet to be widely evaluated in realistic applications and questions remain regarding the optimal design of ML-ROMs. In this study, we investigate the application of a non-intrusive parametric ML-ROM to a nonlinear, time-dependent fluid dynamics problem in a complex 3D geometry. We construct the ML-ROM using POD for dimensionality reduction and neural networks for interpolation of the ROM coefficients. We compare three different network designs in terms of approximation accuracy and performance. We test our ML-ROM on a flow problem in intracranial aneurysms, where flow variability effects are important when evaluating rupture risk and simulating treatment outcomes. The best-performing network design in our comparison used a two-stage POD reduction, a technique rarely used in previous studies. The best-performing ROM achieved mean test accuracies of 98.6% and 97.6% in the parent vessel and the aneurysm, respectively, while providing speed-up factors of the order 10 5 .

Childhood family environment and systemic haemodynamics in adulthood: the Cardiovascular Risk in Young Finns Study.

AIMS: Childhood family environment is associated with adulthood health behaviours and cardiovascular health, but limited data are available concerning the relationship between childhood family environment and adulthood haemodynamic determinants of blood pressure. We evaluated how childhood family environment predicts adulthood systemic haemodynamics. METHODS: The sample came from the Cardiovascular Risk in Young Finns Study (n=1554-1620). Childhood family environment (1980) was assessed with four cumulative risk scores: socioeconomic family risk, risky emotional family atmosphere, stressful life events, and parents' risky health behaviours. Haemodynamic outcomes in 2007 (participants being 30-45 year-olds) included stroke volume index, systemic vascular resistance index, cardiac output index and heart rate. Analyses were adjusted for childhood (1980) cardiovascular risk factors (high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides, insulin, body mass index and systolic blood pressure); and adulthood (2007) health behaviours (alcohol consumption, smoking, physical activity); and finally for adulthood cardiovascular risk factors. RESULTS: When adjusted for age and sex, high socioeconomic family risk predicted lower stroke volume index (P=0.001), higher heart rate (P=0.001) and higher systemic vascular resistance index (P=0.030). These associations remained after controlling for childhood cardiovascular covariates or adulthood health behaviours (P⩽0.02 for all) but diluted after controlling for adulthood cardiovascular risk factors. The other childhood cumulative risk scores (stressful life events, risky emotional atmosphere, or parents' risky health behaviour) did not predict adulthood haemodynamic outcomes. CONCLUSIONS: High childhood socioeconomic family risk predicted adulthood haemodynamic outcomes independently of childhood cardiovascular risk factors and adulthood health behaviours, while other childhood psychosocial adversities were not associated with cardiovascular function in adulthood.

Comparative analysis of peri-nidal cerebral blood flow and metabolism using a novel quantitative 15O-PET method in patients with arteriovenous malformations.

To effectively treat cerebral arteriovenous malformations (AVMs), peri-nidal flow regulation and metabolic status must be understood. In this study, we used 15O-oxygen positron emission tomography (PET) post-processing analysis to investigate vascular radioactivity in the nidal region of AVMs. Single-dynamic PET imaging was performed on seven unruptured AVM patients during the sequential inhalation of 15O2 and C15O2. A previously validated dual-tracer basis function method (DBFM) was employed to calculate parametric images. The results of our study were as follows. First, in remote and contralateral AVM regions, DBFM and a previous approach of dual-tracer autoradiography (DARG) showed strong positive correlations in cerebral blood flow (CBF), cerebral oxygen metabolism rate (CMRO2), and oxygen extraction fraction. Second, peri-nidal CBF and CMRO2 correlation was lower, and overestimation occurred with DARG compared to with DBFM. Third, on comparing DBFM to quantitative 123I-iodoamphetamine single-photon emission computed tomography (SPECT), CBF correlated significantly. In contrast, the correlation between DARG and quantitative 123I-iodoamphetamine-SPECT was weaker in the peri-nidal regions. Fourth, analysis of tissue time-activity curves demonstrated good reproducibility using the novel formulation in the control, peri-nidus, and core nidal regions, indicating the adequacy of this approach. Overall, the DBFM approach holds promise for assessing haemodynamic alterations in patients with AVMs.

Blood pressure increase preceded spontaneous and paracetamol-induced, early ductal closure in very preterm infants.

AIM: To investigate the blood pressure (BP) and ductal calibre patterns associated with early ductal closure in very low gestational age (<32 weeks) infants. METHODS: Blood pressure was continuously measured intra-arterially among 43 infants participating in a randomised, double-blind trial of 4 days prophylactic intravenous paracetamol. Early closure of the ductus was verified by daily ultrasound examinations. The BP recordings, before and after the verified ductal closure, were examined and compared to control infants without ductal closure. In the 24-h preceding the ultrasound-verified ductal closure, periods of increased BP were searched and identified as suggestive ductal closure time points. In control infants without ductal closure, BP trends were examined during the corresponding age. RESULTS: Mean arterial BP increased significantly before ductal closure (p < 0.001) and stayed higher than in the control group. Mean BP during the 8 h preceding closure significantly predicted the ductal closure [OR 2.094 (95% CI 1.209-3.630), p = 0.008], and multiple potential confounders failed to abolish this association. A linear decrease pattern in ductal calibre was significantly associated with the ductal closure. CONCLUSION: Blood pressure increased and stabilised before the early ductal closure, offering potential implications on treatment strategies of very premature infants.

Additive value of invasive haemodynamic assessment for predicting post-operative outcomes after Fontan.

Routine pre-Fontan cardiac catheterization remains standard practice at most centres. However, with advances in non-invasive risk assessment, an invasive haemodynamic assessment may not be necessary for all patients.Using retrospective data from patients undergoing Fontan palliation at our institution, we developed a multivariable model to predict the likelihood of a composite adverse post-operative outcome including prolonged length of stay ≥ 30 days, hospital readmission within 6 months, and death and/or transplant within 6 months. Our baseline model included non-invasive risk factors obtained from clinical history and echocardiogram. We then incrementally incorporated invasive haemodynamic data to determine if these variables improved risk prediction.Our baseline model correctly predicted favourable versus adverse post-Fontan outcomes in 118/174 (68%) patients. Covariates associated with adverse outcomes included the presence of a systemic right ventricle (adjusted adds ratio [aOR] 2.9; 95% CI 1.4, 5.8; p = 0.004), earlier surgical era (aOR 3.1 for era 1 vs 2; 95% CI 1.5, 6.5; p = 0.002), and performance of concomitant surgical procedures at the time of Fontan surgery (aOR 2.5; 95% CI 1.1, 5.0; p = 0.026). Incremental addition of invasively acquired haemodynamic data did not improve model performance or percentage of outcomes predicted.Invasively acquired haemodynamic data does not add substantially to non-invasive risk stratification in the majority of patients. Pre-Fontan catheterization may still be beneficial for angiographic evaluation of anatomy, for therapeutic intervention, and in select patients with equivocal risk stratification.

Fluid-structure interaction analysis of a healthy aortic valve and its surrounding haemodynamics.

The opening and closing dynamics of the aortic valve (AV) has a strong influence on haemodynamics in the aortic root, and both play a pivotal role in maintaining normal physiological functions of the valve. The aim of this study was to establish a subject-specific fluid-structure interaction (FSI) workflow capable of simulating the motion of a tricuspid healthy valve and the surrounding haemodynamics under physiologically realistic conditions. A subject-specific aortic root was reconstructed from magnetic resonance (MR) images acquired from a healthy volunteer, whilst the valve leaflets were built using a parametric model fitted to the subject-specific aortic root geometry. The material behaviour of the leaflets was described using the isotropic hyperelastic Ogden model, and subject-specific boundary conditions were derived from 4D-flow MR imaging (4D-MRI). Strongly coupled FSI simulations were performed using a finite volume-based boundary conforming method implemented in FlowVision. Our FSI model was able to simulate the opening and closing of the AV throughout the entire cardiac cycle. Comparisons of simulation results with 4D-MRI showed a good agreement in key haemodynamic parameters, with stroke volume differing by 7.5% and the maximum jet velocity differing by less than 1%. Detailed analysis of wall shear stress (WSS) on the leaflets revealed much higher WSS on the ventricular side than the aortic side and different spatial patterns amongst the three leaflets.

Haemodynamic study of left nonthrombotic iliac vein lesions: a preliminary report.

Nonthrombotic iliac vein lesions (NIVLs) are significant causes of chronic venous insufficiency (CVI) in the left lower limb and symptom recurrence following left lower limb varicose vein treatment. The goal of this study was to explore the haemodynamic and morphological characteristics of iliac veins in patients with NIVLs. Pressure at the caudal end of the stenotic left common iliac vein (LCIV) segment, local blood flow velocity, and time-averaged wall shear stress in the stenotic segment exhibited positive correlations with the clinical CVI classification (R = 0.92, p < 0.001; R = 0.94, p < 0.001; R = 0.87, p < 0.001), while the relative retention time showed a negative correlation (R = -0.94, p < 0.001). The pressure difference (∆P) between the two ends of the stenotic segment and the velocity difference (∆V) between the stenotic segment and the caudal end were positively correlated with the clinical classification (R = 0.92, p < 0.001; R = 0.9, p < 0.001). The cross-sectional area stenosis rate and length of the stenotic LCIV segment were positively correlated with the clinical classification (R = 0.93, p < 0.001; R = 0.63, p < 0.001). The results suggest that haemodynamic assessment of the iliac vein could effectively portray blood flow disturbances in stenotic segments of the LCIV, potentially reflecting the degree of iliac vein stenosis. Haemodynamic indicators are correlated with the severity of clinical CVI symptoms.

The combined effects of temperature and posture on regional blood flow and haemodynamics.

Under simultaneous ambient temperature and postural stressors, integrated regional blood flow responses are required to maintain blood pressure and thermoregulatory homeostasis. The aim of the present study was to assess the effect of ambient temperature and body posture on regional regulation of microvascular blood flow, specifically in the arms and legs. Participants (N = 11) attended two sessions in which they experienced transient ambient conditions, in a climatic chamber. During each 60-min trial, ambient temperature increased from 15.7 (0.6) °C to 38.9 (0.6) °C followed by a linear decrease, and the participants were either standing or in a supine position throughout the trial; relative humidity in the chamber was maintained at 25.9 (6.6) %. Laser doppler flowmetry of the forearm (SkBFarm) and calf (SkBFcalf), and haemodynamic responses (heart rate, HR; stroke volume, SV; cardiac output, CO; blood pressure, BP), were measured continuously. Analyses of heart rate variability and wavelet transform were also conducted. SkBFarm increased significantly at higher ambient temperatures (p = 0.003), but not SkBFcalf. The standing posture caused lower overall SkBF in both regions throughout the protocol, regardless of temperature (p < 0.001). HR and BP were significantly elevated, and SV significantly lowered, in response to separate and combined effects of higher ambient temperatures and a standing position (all p < 0.05); CO remained unchanged. Mechanistic analyses identified greater sympathetic nerve activation, and higher calf myogenic activation at peak temperatures, in the standing condition. Mechanistically and functionally, arm vasculature responds to modulation from both thermoregulation and baroreceptor activity. The legs, meanwhile, are more sensitive to baroreflex regulatory mechanisms.

Noninvasive and fast method of calculation for instantaneous wave-free ratio based on haemodynamics and deep learning.

BACKGROUND AND OBJECTIVES: Instantaneous wave-free ratio (iFR) is a new invasive indicator of myocardial ischaemia, and its diagnostic performance is as good as the "gold standard" of myocardial ischaemia diagnosis: fractional flow reserve (FFR). iFR can be approximated by iFRCT, which is calculated based on noninvasive coronary CT angiography (CTA) images and computational fluid dynamics (CFD). However, the existing methods for calculating iFRCT fail to accurately simulate the resting state of the coronary artery, resulting in low computational accuracy. Furthermore, the use of CFD technology limits its computational efficiency, making it difficult to meet clinical application needs. The role of coronary microcirculatory resistance compensation suggests that microcirculatory resistance can be adaptively reduced to compensate for increases in coronary stenotic resistance, thereby maintaining stable myocardial perfusion in the resting state. It is therefore necessary to consider this compensation mechanism to establish a high-fidelity microcirculation resistance model in the resting state in line with human physiology, and so to achieve accurate calculation of iFRCT. METHODS: In this study we successfully collected clinical data, such as FFR, in 205 stenotic vessels from 186 patients with coronary heart disease. A neural network model was established to predict coronary artery stenosis resistance. Based on the compensation mechanism of coronary microcirculation resistance, an iterative solution algorithm for microcirculation resistance in the resting state was developed. Combining the two methods, a simplified single-branch model combining coronary stenosis and microcirculation resistance was established, and the noninvasive and rapid numerical calculation of iFRCT was performed. RESULTS: The results showed that the mean squared error (MSE) between the pressure drop predicted by the neural network value for the coronary artery stenosis model and the ground truth in the test set was 0.053 %, and correlation analysis proved that there was a good correlation between them (r = 0.99, p < 0.001). With reference to clinical diagnosis of myocardial ischaemia (using FFR as the gold standard), the diagnostic accuracy of the iFRCT calculation model for the 205 cases was 88.29 % (r = 0.71, p < 0.001), and the total calculation time was < 8 s. CONCLUSIONS: The results of this study demonstrate the utility of a simplified single-branch model in an iFRCT calculation method based on haemodynamics and deep learning, which is important for noninvasive and rapid diagnosis of myocardial ischaemia.

Menstrual cycle status does not impact exercise-based changes in cerebral blood flow or executive function benefits.

A single bout of exercise enhances executive function (EF) and may relate to an increase in cerebral blood flow (CBF). A limitation in the current literature is that biologically female participants are underrepresented given some evidence that changes in hormone levels across the menstrual cycle impact physiological and psychological variables. Here, biologically female participants completed separate single bouts of moderate intensity exercise (80% of estimated lactate threshold) during the follicular (FOL) and luteal (LUT) phases of their menstrual cycle. In addition, biologically male participants completed a same duration/intensity exercise session. Middle cerebral artery velocity (MCAv) was used to estimate CBF and pre- and postexercise EF was assessed via the antisaccade task. Results showed that resting MCAv was larger in the LUT than FOL phase; however, the exercise-mediated increase in MCAv was equivalent between menstrual cycle phases, and between female and male participants. Antisaccade reaction times reliably decreased from pre- to postexercise and frequentist and non-frequentist statistics demonstrated that the magnitude of the decrease was equivalent across FOL and LUT phases, and between female and male participants. Thus, results evince that menstrual cycle status should not serve as a basis limiting biologically female participants' inclusion in research examining exercise and EF.

Haemodynamic contributors to pulmonary hypertension across the spectrum of adult congenital heart disease.

AIMS: Adult congenital heart disease (ACHD) includes multiple disease states that predispose to pulmonary hypertension (PH). Haemodynamically, PH depends on abnormalities in three components: pulmonary blood flow (Qp), pulmonary vascular resistance (PVR) and pulmonary venous pressure (PVP). We sought to evaluate the prevalence and prognostic impact of individual haemodynamic abnormalities in ACHD. METHODS AND RESULTS: Retrospective study of ACHD patients undergoing cardiac catheterization at Mayo Clinic between 1999 and 2022 who were followed for the combined endpoint of death/heart transplantation. Among 1005 patients, 37% had mean pulmonary artery pressure (mPAP) ≥25 mmHg with more systemic ventricular disease, cyanotic disease and shunt lesions, highest N-terminal pro-B-type natriuretic peptide and worse right heart remodelling/dysfunction. Among those with biventricular circulation, elevated PVP, PVR and mPAP were associated with prognosis, but not increased Qp >8 L/min. However, risk of death/transplant increased for PVR only at ≥3 Wood units (hazard ratio [HR] 3.00, 95% confidence interval [CI] 2.17-4.15; p < 0.0001) and for mPAP only at ≥25 mmHg (HR 3.15, 95% CI 2.17-4.58; p < 0.0001), not at current recommended lower cutpoints. Combined abnormalities in PVP and PVR were associated with worst outcome (HR 5.20, 95% CI 3.55-7.63; p < 0.0001) with intermediate risk with either abnormality (HR 2.11, 95% CI 1.46-3.04; p < 0.0001). Findings were consistent across type of biventricular ACHD. Only with the Fontan (univentricular) circulation was a lower mPAP threshold (20 mmHg) associated with adverse outcomes. CONCLUSIONS: Elevation of mPAP ≥25 mmHg in ACHD with a biventricular circulation is prognostically important regardless of disease phenotype, but milder PH of 21-25 mmHg is not associated with adverse outcome unless associated with Fontan circulation. Elevation in PVP >15 mmHg and PVR ≥3 Wood units were each individually associated with mortality with combined abnormalities associated with greatest risk. Categorizing PH in ACHD by haemodynamic mechanism (PVR, PVP or Qp) allows meaningful prognostication, and may allow more unified study of targeted therapies across heterogeneous disease states in ACHD.

Intubation of critically ill patients: A pilot study of minute-by-minute physiological changes within an Australian tertiary intensive care unit.

BACKGROUND: There are no published minute-by-minute physiological assessment data for endotracheal intubation (ETT) performed in the intensive care unit (ICU). The majority of physiological data is available from Europe and North America where etomidate is the induction agent administered most commonly. AIMS: The aim of this study was to describe the feasibility of obtaining minute-by-minute physiological and medication data surrounding ETT in an Australian tertiary ICU and to assess its associated outcomes. METHODS: We performed a single-centre feasibility observational study. We obtained minute-by-minute data on physiological variables and medications for 15 min before and 30 min after ETT. We assessed feasibility as enrolled to screened patient ratio and completeness of data collection in enrolled patients. Severe hypotension (systolic blood pressure < 65 mmHg) and severe hypoxaemia (pulse oximetry saturation < 80%) were the secondary clinical outcomes. RESULTS: We screened 43 patients and studied 30 patients. The median age was 58.5 (interquartile range: 49-70) years, and 18 (60%) were male. Near-complete (97%) physiological and medication data were obtained in all patients at all times. Overall, 15 (50%) ETTs occurred after hours (17:30-08:00) and 90% were by video laryngoscopy with a 90% first-pass success rate. Prophylactic vasopressors were used in 50% of ETTs. Fentanyl was used in all except one ETT at a median dose of 2.5 mcg/kg. Propofol (63%) or midazolam (50%) were used as adjuncts at low dose. Rocuronium was used in all but one patient. There were no episodes of severe hypotension and only one episode of short-lived severe hypoxaemia. CONCLUSION: Minute-by-minute recording of ETT-associated physiological changes in the ICU was feasible but only fully available in two-thirds of the screened patients. ETT was based on fentanyl induction, low-dose adjunctive sedation, and frequent prophylactic vasopressor therapy and was associated with no severe hypotension and a single short-lived episode of severe hypoxaemia.