Evaluating the accuracy of cerebrovascular computational fluid dynamics modeling through time-resolved experimental validation.

Accurate modeling of cerebral hemodynamics is crucial for better understanding the hemodynamics of stroke, for which computational fluid dynamics (CFD) modeling is a viable tool to obtain information. However, a comprehensive study on the accuracy of cerebrovascular CFD models including both transient arterial pressures and flows does not exist. This study systematically assessed the accuracy of different outlet boundary conditions (BCs) comparing CFD modeling and an in-vitro experiment. The experimental setup consisted of an anatomical cerebrovascular phantom and high-resolution flow and pressure data acquisition. The CFD model of the same cerebrovascular geometry comprised five sets of stationary and transient BCs including established techniques and a novel BC, the phase modulation approach. The experiment produced physiological hemodynamics consistent with reported clinical results for total cerebral blood flow, inlet pressure, flow distribution, and flow pulsatility indices (PI). The in-silico model instead yielded time-dependent deviations between 19-66% for flows and 6-26% for pressures. For cerebrovascular CFD modeling, it is recommended to avoid stationary outlet pressure BCs, which caused the highest deviations. The Windkessel and the phase modulation BCs provided realistic flow PI values and cerebrovascular pressures, respectively. However, this study shows that the accuracy of current cerebrovascular CFD models is limited.

Validation of a Suprasystolic Cuff System for Static and Dynamic Representation of the Central Pressure Waveform.

BACKGROUND: Noninvasive pulse waveform analysis is valuable for central cardiovascular assessment, yet controversies persist over its validity in peripheral measurements. Our objective was to compare waveform features from a cuff system with suprasystolic blood pressure hold with an invasive aortic measurement. METHODS AND RESULTS: This study analyzed data from 88 subjects undergoing concurrent aortic catheterization and brachial pulse waveform acquisition using a suprasystolic blood pressure cuff system. Oscillometric blood pressure (BP) was compared with invasive aortic systolic BP and diastolic BP. Association between cuff and catheter waveform features was performed on a set of 15 parameters inclusive of magnitudes, time intervals, pressure-time integrals, and slopes of the pulsations. The evaluation covered both static (subject-averaged values) and dynamic (breathing-induced fluctuations) behaviors. Peripheral BP values from the cuff device were higher than catheter values (systolic BP-residual, 6.5 mm Hg; diastolic BP-residual, 12.4 mm Hg). Physiological correction for pressure amplification in the arterial system improved systolic BP prediction (r2=0.83). Dynamic calibration generated noninvasive BP fluctuations that reflect those invasively measured (systolic BP Pearson R=0.73, P<0.001; diastolic BP Pearson R=0.53, P<0.001). Static and dynamic analyses revealed a set of parameters with strong associations between catheter and cuff (Pearson R>0.5, P<0.001), encompassing magnitudes, timings, and pressure-time integrals but not slope-based parameters. CONCLUSIONS: This study demonstrated that the device and methods for peripheral waveform measurements presented here can be used for noninvasive estimation of central BP and a subset of aortic waveform features. These results serve as a benchmark for central cardiovascular assessment using suprasystolic BP cuff-based devices and contribute to preserving system dynamics in noninvasive measurements.

Development and web deployment of prediction model for pulmonary arterial pressure in chronic thromboembolic pulmonary hypertension using machine learning.

BACKGROUND AND PURPOSE: Mean pulmonary artery pressure (mPAP) is a key index for chronic thromboembolic pulmonary hypertension (CTEPH). Using machine learning, we attempted to construct an accurate prediction model for mPAP in patients with CTEPH. METHODS: A total of 136 patients diagnosed with CTEPH were included, for whom mPAP was measured. The following patient data were used as explanatory variables in the model: basic patient information (age and sex), blood tests (brain natriuretic peptide (BNP)), echocardiography (tricuspid valve pressure gradient (TRPG)), and chest radiography (cardiothoracic ratio (CTR), right second arc ratio, and presence of avascular area). Seven machine learning methods including linear regression were used for the multivariable prediction models. Additionally, prediction models were constructed using the AutoML software. Among the 136 patients, 2/3 and 1/3 were used as training and validation sets, respectively. The average of R squared was obtained from 10 different data splittings of the training and validation sets. RESULTS: The optimal machine learning model was linear regression (averaged R squared, 0.360). The optimal combination of explanatory variables with linear regression was age, BNP level, TRPG level, and CTR (averaged R squared, 0.388). The R squared of the optimal multivariable linear regression model was higher than that of the univariable linear regression model with only TRPG. CONCLUSION: We constructed a more accurate prediction model for mPAP in patients with CTEPH than a model of TRPG only. The prediction performance of our model was improved by selecting the optimal machine learning method and combination of explanatory variables.

Blood pressure trends following birth in infants born under 25 weeks' gestational age: a retrospective cohort study.

OBJECTIVE: The aim of our study was to describe postnatal blood pressure (BP) trends and evaluate relevant dynamics and outcomes for a subgroup of extremely preterm (EPT) infants. DESIGN: Retrospective observational cohort study. SETTING: Patients admitted to Karolinska University Hospital Stockholm. PATIENTS: EPT infants born between 22+0 and 24+6 weeks' gestational age (GA) undergoing invasive, continuous BP monitoring through an umbilical arterial catheter. MAIN OUTCOME MEASURES: Physiological BP trends, the influence of cardiovascular active interventions and fluid boluses on BP, and relevant adverse outcomes, including intraventricular haemorrhage (IVH), necrotising enterocolitis (NEC) and death, were mapped over the first week of life. RESULTS: We included 125 infants between January 2009 and November 2021. Mean BP values were 31 mm Hg, 32 mm Hg and 35 mm Hg, at 3 hours, 24 hours and 48 hours, respectively. A pronounced BP dip and nadir were observed around 20 hours, with a mean BP value of 32 mm Hg. 84% received fluid boluses within the first week of life; however, we could not observe any noteworthy change in BP following administration. Only 8% of patients received cardiovascular active drugs, which were too few to infer drug-specific effects. Overall, 48% developed IVH, 15% developed NEC and 25% died. CONCLUSIONS: Approximating clinically acceptable mean BP values using GA gives underestimations in these infants. The postnatal BP dip should be regarded as a physiological phenomenon and not automatic grounds for interventions which may momentarily stabilise BP but have no appreciable short-term or long-term effects. Further studies are warranted for improved understanding of clinically relevant trends and outcomes.

Finger cuff versus invasive and noninvasive arterial pressure measurement in pregnant patients with obesity.

BACKGROUND: Pregnant patients with obesity may have compromised noninvasive blood pressure (NIBP) measurement. We assessed the accuracy and trending ability of the ClearSight™ finger cuff (FC) with invasive arterial monitoring (INV) and arm NIBP, in obese patients having cesarean delivery. METHODS: Participants were aged ≥18 years, ≥34 weeks gestation, and body mass index (BMI) ≥ 40 kg m-2. FC, INV, and NIBP measurements were obtained across 5-min intervals. The primary outcome was agreement of FC measurements with those of the reference standard INV, using modified Bland-Altman plots. Secondary outcomes included comparisons between FC and NIBP and NIBP versus INV, with four-quadrant plots performed to report discordance rates and evaluate trending ability. RESULTS: Twenty-three participants had a median (IQR) BMI of 45 kg m-2 (44-48). When comparing FC and INV the mean bias (SD, 95% limits of agreement) for systolic blood pressure (SBP) was 16 mmHg (17, -17.3 to 49.3 mmHg), for diastolic blood pressure (DBP) -0.2 mmHg (10.5, -20.7 to 20.3), and for mean arterial pressure (MAP) 5.2 mmHg (11.1, -16.6 to 27.0 mmHg). Discordance occurred in 54 (26%) pairs for SBP, 41 (23%) for DBP, and 41 (21.7%) for MAP. Error grid analysis showed 92.1% of SBP readings in Zone A (no-risk zone). When comparing NIBP and INV, the mean bias (95% limits of agreement) for SBP was 13.0 mmHg (16.7, -19.7 to 29.3), for DBP 5.9 mmHg (11.9, -17.4 to 42.0), and for MAP 8.2 mmHg (11.9, -15.2 to 31.6). Discordance occurred in SBP (84 of 209, 40.2%), DBP (74 of 187, 39.6%), and MAP (63 of 191, 33.0%). CONCLUSIONS: The FC and NIBP techniques were not adequately in agreement with INV. Trending capability was better for FC than NIBP. Clinically important differences may occur in the setting of the perfusion-dependent fetus.

Short-term vascular responses to spring and fall daylight savings time shifts.

Daylight saving time (DST) is a Western biannual time transition, setting the clock back 1 h in the fall and forward 1 h in the spring. There is an epidemiological link between DST and acute myocardial infarction risk in the first week following the spring shift; however, the mechanisms underlying the effect of DST on cardiovascular function remain unclear. The purpose of this study was to explore the short-term cardiovascular changes induced by fall and spring shifts in DST in a convenience sample of healthy adults. We hypothesized that spring, but not fall, DST shifts would acutely increase central pulse wave velocity, the gold standard measurement of central arterial stiffness. Twenty-one individuals (fall: n = 10; spring: n = 11) participated in four visits, occurring 1 wk before and at +1, +3, and +5 days after spring and fall time transitions. Central, brachial, and radial pulse wave velocity as well as carotid augmentation index were assessed with applanation tonometry. Sleep quality and memory function were assessed via questionnaire and the Mnemonic Similarities Task, respectively. Neither fall or spring transition resulted in changes to cardiovascular variables (carotid-femoral pulse wave velocity, carotid-brachial pulse wave velocity, carotid-radial pulse wave velocity, heart rate, mean arterial pressure, or augmentation index), sleep quality, or cognitive function (all P > 0.05). Our findings do not provide evidence that DST shifts influence cardiovascular outcomes in healthy adults. This study emphasizes the need for further research to determine the mechanisms of increased cardiovascular disease risk with DST that help explain epidemiological trends.NEW & NOTEWORTHY The debate of whether to abolish daylight savings time (DST) is, in part, motivated by the population-level increase in all-cause mortality and incidence of cardiovascular events following DST; however, there is an absence of data to support a physiological basis for risk. We found no changes in pulse wave velocity or augmentation index during the subacute window of DST. Large multisite trials are necessary to address the small, but meaningful, effects brought on by a societal event.

Mean Arterial Pressure (MAP) Trial: study protocol for a multicentre, randomized, controlled trial to compare three different strategies of mean arterial pressure management during cardiopulmonary bypass.

BACKGROUND: One of the main goals of cardiopulmonary bypass (CPB) is targeting an adequate mean arterial pressure (MAP) during heart surgery, in order to maintain appropriate perfusion pressures in all end-organs. As inheritance of early studies, a value of 50-60 mmHg has been historically accepted as the "gold standard" MAP. However, in the last decades, the CPB management has remarkably changed, thanks to the evolution of technology and the availability of new biomaterials. Therefore, as highlighted by the latest European Guidelines, the current management of CPB can no longer refer to those pioneering studies. To date, only few single-centre studies have compared different strategies of MAP management during CPB, but with contradictory findings and without achieving a real consensus. Therefore, what should be the ideal strategy of MAP management during CPB is still on debate. This trial is the first multicentre, randomized, controlled study which compares three different strategies of MAP management during the CPB. METHODS: We described herein the methodology of a multicentre, randomized, controlled trial comparing three different approaches to MAP management during CPB in patients undergoing elective cardiac surgery: the historically accepted "standard MAP" (50-60 mmHg), the "high MAP" (70-80 mmHg) and the "patient-tailored MAP" (comparable to the patient's preoperative MAP). It is the aim of the study to find the most suitable management in order to obtain the most adequate perfusion of end-organs during cardiac surgery. For this purpose, the primary endpoint will be the peak of serum lactate (Lmax) released during CPB, as index of tissue hypoxia. The secondary outcomes will include all the intraoperative parameters of tissue oxygenation and major postoperative complications related to organ malperfusion. DISCUSSION: This trial will assess the best strategy to target the MAP during CPB, thus further improving the outcomes of cardiac surgery. TRIAL REGISTRATION: NCT05740397 (retrospectively registered; 22/02/2023).

Influence of a Decrease in Blood Viscosity on Arterial Pressure in Normotensive and Spontaneously Hypertensive Rats.

We investigated the effect of a decrease in blood viscosity on the mean BP during isovolumic hemodilution and vasodilating activity of the endothelium in normotensive Wistar rats and spontaneously hypertensive rats (SHR). Blood viscosity was reduced by isovolumic hemodilution (replacement of 10% of circulating blood with an equal volume of plasma). Hemodilution caused the same reduction in blood viscosity by 16% in both groups of rats. In Wistar rats, a decrease in blood viscosity did not significantly change in the mean BP; no significant correlations between blood viscosity and mean BP were observed before and after hemodilution. In SHR, a decrease in blood viscosity led to a significant decrease in the mean BP by 18%. Correlations were found between the mean BP and blood viscosity in SHR before (r=0.63; p=0.028) and after (r=0.71; p=0.009) isovolumic hemodilution. In SHR, a decrease in the index of vasodilating activity of the endothelium due to a decrease in the vasodilatory response to intravenous administration of the endothelium-dependent vasodilator acetylcholine was revealed. In SHR, BP passively follows the change, in this case, the decrease in blood viscosity, which attests to impaired BP regulation in response to changes in shear stress on the vascular endothelium caused by the development of endothelial dysfunction in hypertensive animals.

Gender Differences in Cardiac Organ Damage in Arterial Hypertension: Assessing the Role of Drug Nonadherence.

INTRODUCTION: Cardiac organ damage like left ventricular (LV) hypertrophy and left atrial (LA) enlargement is more prevalent in women than men with hypertension, but the mechanisms underlying this gender difference remain unclear. METHODS: We tested the association of drug nonadherence with the presence of LV hypertrophy and LA enlargement by echocardiography in 186 women and 337 men with uncontrolled hypertension defined as daytime systolic blood pressure (BP) ≥ 135mmHg despite the prescription of at least two antihypertensive drugs. Drug adherence was assessed by measurements of serum drug concentrations interpreted by an experienced pharmacologist. Aldosterone-renin-ratio (ARR) was measured on actual medication. RESULTS: Women had a higher prevalence of LV hypertrophy (46% vs. 33%) and LA enlargement (79% vs 65%, both p < 0.05) than men, while drug nonadherence (8% vs. 9%, p > 0.514) did not differ. Women were older and had lower serum renin concentration and higher ARR than men, while 24-h systolic BP (141 ± 9 mmHg vs. 142 ± 9 mmHg), and the prevalences of obesity (43% vs. 50%) did not differ (all p > 0.10). In multivariable analyses, female gender was independently associated with a two-fold increased risk of LV hypertrophy (OR 2.01[95% CI 1.30-3.10], p = 0.002) and LA enlargement (OR 1.90 [95% CI 1.17-3.10], p = 0.010), while no association with drug nonadherence was found. Higher ARR was independently associated with LV hypertrophy in men only (OR 2.12 [95% CI 1.12-4.00] p = 0.02). CONCLUSIONS: Among patients with uncontrolled hypertension, the higher prevalence of LV hypertrophy and LA enlargement in women was not explained by differences in drug nonadherence. REGISTRATION: URL:  https://www. CLINICALTRIALS: gov ; Unique identifier: NCT03209154.

Activation of cardiac parasympathetic and sympathetic activity occurs at different skin temperatures during face cooling.

Sufficiently cold-water temperatures (<7°C) are needed to elicit the sympathetic response to the cold pressor test using the hand. However, it is not known if stimulating the trigeminal nerve via face cooling, which increases both sympathetic and cardiac parasympathetic activity, also has a threshold temperature. We tested the hypothesis that peak autonomic activation during a progressive face cooling challenge would be achieved when the stimulus temperature is ≤7°C. Twelve healthy participants (age: 25 ± 3 yr, four women) completed our study. Six pliable bags, each containing water or an ice slurry (34°C, 28°C, 21°C, 14°C, 7°C, and 0°C) were applied sequentially to participants' forehead, eyes, and cheeks for 5 min each. Mean arterial pressure (photoplethysmography; index of sympathetic activity) and heart rhythm (3-lead ECG) were averaged in 1-min increments at the end of baseline and throughout each temperature condition. Heart rate variability in the time [(root mean square of successive differences (RMSSD)] and frequency [high-frequency (HF) power] domains was used to estimate cardiac parasympathetic activity. Data are presented as the increase from baseline ± SD. Mean arterial pressure only increased from baseline in the 7°C (13.1 ± 10.3 mmHg; P = 0.018) and 0°C (25.2 ± 7.8 mmHg; P < 0.001) conditions. Only the 0°C condition increased RMSSD (160.6 ± 208.9 ms; P = 0.009) and HF power (11,450 ± 14,555 ms2; P = 0.014) from baseline. Our data indicate that peak increases in sympathetic activity during face cooling are initiated at a higher forehead skin temperature than peak increases in cardiac parasympathetic activity.

Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK helicopter emergency medical service- a retrospective observational review of practice.

BACKGROUND: Accurate haemodynamic monitoring in the prehospital setting is essential. Non-invasive blood pressure measurement is susceptible to vibration and motion artefact, especially at extremes of hypotension and hypertension: invasive arterial blood pressure (IABP) monitoring is a potential solution. This study describes the largest series to date of cases of IABP monitoring being initiated prehospital. METHODS: This retrospective observational study was conducted at East Anglian Air Ambulance (EAAA), a UK helicopter emergency medical service (HEMS). It included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 and 20th April 2023. The following data were retrieved for all patients: sex; age; aetiology (medical cardiac arrest, other medical emergency, trauma); site of arterial cannulation; operator role (doctor/paramedic); time of insertion and, where applicable, times of pre-hospital emergency anaesthesia, and return of spontaneous circulation following cardiac arrest. Descriptive analyses were performed to characterise the sample. RESULTS: 13,556 patients were attended: IABP monitoring was initiated in 1083 (8.0%) cases, with a median age 59 years, of which 70.8% were male. 546 cases were of medical cardiac arrest: in 22.4% of these IABP monitoring was initiated during cardiopulmonary resuscitation. 322 were trauma cases, and the remaining 215 were medical emergencies. The patients were critically unwell: 981 required intubation, of which 789 underwent prehospital emergency anaesthesia; 609 received vasoactive medication. In 424 cases IABP monitoring was instituted en route to hospital. CONCLUSION: This study describes over 1000 cases of prehospital arterial catheterisation and IABP monitoring in a UK HEMS system and has demonstrated feasibility at scale. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting.

Novel theory and potential applications of central diastolic pressure decay time constant.

Central aortic diastolic pressure decay time constant ( τ ) is according to the two-element Windkessel model equal to the product of total peripheral resistance ( R ) times total arterial compliance ( C ). As such, it is related to arterial stiffness, which has considerable pathophysiological relevance in the assessment of vascular health. This study aimed to investigate the relationship of the constant τ with the product T MBP cPP , given by heart period ( T ) times the ratio of mean blood pressure (MBP) to central pulse pressure ( cPP ). The relationship was derived by performing linear fitting on an in silico population of n1 = 3818 virtual subjects, and was subsequently evaluated on in vivo data (n2 = 2263) from the large Asklepios study. The resulted expression was found to be τ = k ' T MBP cPP , with k ' = 0.7 (R2 = 0.9). The evaluation of the equation on the in vivo human data reported high agreement between the estimated and reference τ values, with a correlation coefficient equal to 0.94 and a normalized RMSE equal to 5.5%. Moreover, the analysis provided evidence that the coefficient k ' is age- and gender-independent. The proposed formula provides novel theoretical insights in the relationship between τ and central blood pressure features. In addition, it may allow for the evaluation of τ without the need for acquiring the entire central blood pressure wave, especially when an approximation of the cPP is feasible. This study adds to the current literature by contributing to the accessibility of an additional biomarker, such as the central diastolic pressure decay time constant, for the improved assessment of vascular ageing.

Myths and methodologies: Assessment of dynamic cerebral autoregulation by the mean flow index.

The mean flow index-usually referred to as Mx-has been used for assessing dynamic cerebral autoregulation (dCA) for almost 30 years. However, concerns have arisen regarding methodological consistency, construct and criterion validity, and test-retest reliability. Methodological nuances, such as choice of input (cerebral perfusion pressure, invasive or non-invasive arterial pressure), pre-processing approach and artefact handling, significantly influence mean flow index values, and previous studies correlating mean flow index with other established dCA metrics are confounded by inherent methodological flaws like heteroscedasticity, while the mean flow index also fails to discriminate individuals with presumed intact versus impaired dCA (discriminatory validity), and its prognostic performance (predictive validity) across various conditions remains inconsistent. The test-retest reliability, both within and between days, is generally poor. At present, no single approach for data collection or pre-processing has proven superior for obtaining the mean flow index, and caution is advised in the further use of mean flow index-based measures for assessing dCA, as current evidence does not support their clinical application.

Malignant arrhythmias detection using a synthesis-by-analysis modeling method of arterial blood pressure signal.

Extreme bradycardia, extreme tachycardia, ventricular flutter fib, and ventricular tachycardia are four malignant arrhythmias (MAs) that lead to sudden cardiac death. It is very important to detect them in daily life. The arterial blood pressure (ABP) signal contains abundant pathological information about four MAs and is easy to be recorded under domestic conditions. Thus, a synthesis-by-analysis (SA) modeling method for ABP signal was proposed to detect the four MAs in this study. The average models of MAs and healthy subjects were obtained by SA modeling, and the change of each ABP wave was quantitively described by twelve parameters of wave models. Then, the probabilistic neural network (PNN) and random forest (RF) are trained to detect the MAs. The experimental data were employed from Fantasia and the 2015 PhysioNet/CinC Challenge databases. The SA modeling results show that some pathological and physiological changes could be extracted from the average models. The two-sample ks-test results between different groups are markedly different (h = 1, p < 0.05). The detection results show that the performances of PPN classifiers are less than that of RF. The kappa coefficients (KC) for the RF classifiers are 97.167 ± 1.46 %, 97.888 ± 0.808 %, 99.895 ± 0.545 %, 98.575 ± 1.683 % and 92.241 ± 1.517 %, respectively. The mean KC is 97.083 ± 0.67 %. Compared to the performance of some existing studies, the proposed method has better performance and is potential to diagnose MAs in m-health.

NaHCO3 loading causes increased arterial pressure and kidney damage in rats with chronic kidney disease.

Sodium bicarbonate (NaHCO3) is commonly utilized as a therapeutic to treat metabolic acidosis in people with chronic kidney disease (CKD). While increased dietary sodium chloride (NaCl) is known to promote volume retention and increase blood pressure, the effects of NaHCO3 loading on blood pressure and volume retention in CKD remain unclear. In the present study, we compared the effects of NaCl and NaHCO3 loading on volume retention, blood pressure, and kidney injury in both 2/3 and 5/6 nephrectomy remnant kidney rats, a well-established rodent model of CKD. We tested the hypothesis that NaCl loading promotes greater volume retention and increases in blood pressure than equimolar NaHCO3. Blood pressure was measured 24 h daily using radio telemetry. NaCl and NaHCO3 were administered in drinking water ad libitum or infused via indwelling catheters. Rats were housed in metabolic cages to determine volume retention. Our data indicate that both NaHCO3 and NaCl promote hypertension and volume retention in remnant kidney rats, with salt-sensitivity increasing with greater renal mass reduction. Importantly, while NaHCO3 intake was less pro-hypertensive than equimolar NaCl intake, NaHCO3 was not benign. NaHCO3 loading significantly elevated blood pressure and promoted volume retention in rats with CKD when compared with control rats receiving tap water. Our findings provide important insight into the effects of sodium loading with NaHCO3 in CKD and indicate that NaHCO3 loading in patients with CKD is unlikely to be benign.

Patient-specific non-invasive estimation of the aortic blood pressure waveform by ultrasound and tonometry.

BACKGROUND AND OBJECTIVE: Aortic blood pressure (ABP) is a more effective prognostic indicator of cardiovascular disease than peripheral blood pressure. A highly accurate algorithm for non-invasively deriving the ABP wave, based on ultrasonic measurement of aortic flow combined with peripheral pulse wave measurements, has been proposed elsewhere. However, it has remained at the proof-of-concept stage because it requires a priori knowledge of the ABP waveform to calculate aortic pulse wave velocity (PWV). The objective of this study is to transform this proof-of-concept algorithm into a clinically feasible technique. METHODS: We used the Bramwell-Hill equation to non-invasively calculate aortic PWV which was then used to reconstruct the ABP waveform from non-invasively determined aortic blood flow velocity, aortic diameter, and radial pressure. The two aortic variables were acquired by an ultrasound system from 90 subjects, followed by recordings of radial pressure using a SphygmoCor device. The ABPs estimated by the new algorithm were compared with reference values obtained by cardiac catheterization (invasive validation, 8 subjects aged 62.3 ± 12.7 years) and a SphygmoCor device (non-invasive validation, 82 subjects aged 45.0 ± 17.8 years). RESULTS: In the invasive comparison, there was good agreement between the estimated and directly measured pressures: the mean error in systolic blood pressure (SBP) was 1.4 ± 0.8 mmHg; diastolic blood pressure (DBP), 0.9 ± 0.8 mmHg; mean blood pressure (MBP), 1.8 ± 1.2 mmHg and pulse pressure (PP), 1.4 ± 1.1 mmHg. In the non-invasive comparison, the estimated and directly measured pressures also agreed well: the errors being: SBP, 2.0 ± 1.4 mmHg; DBP, 0.8 ± 0.1 mmHg; MBP, 0.1 ± 0.1 mmHg and PP, 2.3 ± 1.6 mmHg. The significance of the differences in mean errors between calculated and reference values for SBP, DBP, MBP and PP were assessed by paired t-tests. The agreement between the reference methods and those obtained by applying the new approach was also expressed by correlation and Bland-Altman plots. CONCLUSION: The new method proposed here can accurately estimate ABP, allowing this important variable to be obtained non-invasively, using standard, well validated measurement techniques. It thus has the potential to relocate ABP estimation from a research environment to more routine use in the cardiac clinic. SHORT ABSTRACT: A highly accurate algorithm for non-invasively deriving the ABP wave has been proposed elsewhere. However, it has remained at the proof-of-concept stage because it requires a priori knowledge of the ABP waveform to calculate aortic pulse wave velocity (PWV). This study aims to transform this proof-of-concept algorithm into a clinically feasible technique. We used the Bramwell-Hill equation to non-invasively calculate aortic PWV which was then used to reconstruct the ABP waveform. The ABPs estimated by the new algorithm were compared with reference values obtained by cardiac catheterization or a SphygmoCor device. The results showed that there was good agreement between the estimated and directly measured pressures. The new method proposed can accurately estimate ABP, allowing this important variable to be obtained non-invasively, using standard, well validated measurement techniques. It thus has the potential to relocate ABP estimation from a research environment to more routine use in the cardiac clinic.

Elevated Arterial Blood Pressure as a Delayed Complication Following COVID-19-A Narrative Review.

Arterial hypertension is one of the most common and significant cardiovascular risk factors. There are many well-known and identified risk factors for its development. In recent times, there has been growing concern about the potential impact of COVID-19 on the cardiovascular system and its relation to arterial hypertension. Various theories have been developed that suggest a connection between COVID-19 and elevated blood pressure. However, the precise link between SARS-CoV-2 infection and the long-term risk of developing hypertension remains insufficiently explored. Therefore, the primary objective of our study was to investigate the influence of COVID-19 infection on blood pressure elevation and the subsequent risk of developing arterial hypertension over an extended period. To accomplish this, we conducted a thorough search review of relevant papers in the PubMed and SCOPUS databases up to 3 September 2023. Our analysis encompassed a total of 30 eligible articles. Out of the 30 papers we reviewed, 19 of them provided substantial evidence showing a heightened risk of developing arterial hypertension following COVID-19 infection. Eight of the studies showed that blood pressure values increased after the infection, while three of the qualified studies did not report any notable impact of COVID-19 on blood pressure levels. The precise mechanism behind the development of hypertension after COVID-19 remains unclear, but it is suggested that endothelial injury and dysfunction of the renin-angiotensin-aldosterone system may be contributory. Additionally, changes in blood pressure following COVID-19 infection could be linked to lifestyle alterations that often occur alongside the illness. Our findings emphasize the pressing requirement for thorough research into the relationship between COVID-19 and hypertension. These insights are essential for the development of effective prevention and management approaches for individuals who have experienced COVID-19 infection.

[The mobile applications developed for self-control arterial pressure: systematic review and content-analysis].

The high prevalence of arterial hypertension and necessity for permanent monitoring of blood pressure requires implementation of new methods of interaction between patient and physician in order to optimize medical care. The purpose of the study was to describe and to evaluate functional possibilities of Russian-speaking mobile applications utilized in collecting blood pressure readings to monitor efficiency of arterial hypertension treatment. The study was carried out in June 2023 in three mobile application stores: Apple Store, Google Play and RuStore. The Russian-speaking applications applied to hypertension self-controlling were considered. For final analysis 45 mobile applications were selected out of 380 applications tested. The most common functions, besides fixing blood pressure levels, were ability of fixing pulse rate (n=41), weight (n=21), sugar level (n=10), blood oxygen saturation (n=8), cholesterol (n=6), rhythm disturbances (n=6) and body temperature (n=5). Additionally, applications made it possible to add tags (n=33), to view statistics (n=41) (including average blood pressure (n=8), pulse pressure (n=9), average daily blood pressure (n=6) and to compare data for different periods of time (n=6), to filter data by tags (n=17), to export statistics (n=32). The 6 applications also supported technology of wireless reception of blood pressure and emergency data. The educational information about blood pressure was enclosed in 17 applications and dietary advice in 12 applications. The content included basic information about blood pressure, treatment, diet, and physical activity. No clinical studies that proved efficiency or inefficiency of analyzed applications were found. None of descriptions comprised both involvement of physicians in development of application and use of clinical recommendations. The results demonstrated large choice of applications used in recording blood pressure with purpose of hypertension self-control. Besides, mobile applications contain various functions and their combinations that can help patient to control blood pressure more effectively. The physicians are to be aware of capabilities of mobile applications developed with purpose of monitoring health of patients.