Non-invasive Central Blood Pressure Research Articles

NON-INVASIVE CENTRAL BLOOD PRESSURE AND INTRACRANIAL WAVEFORM ASSESSMENT IN HYPERTENSIVE PATIENTS

Objective: Hypertension (HT) remains as the leading cause of death around the globe and brain diseases, such as cognitive decline. The association between HT and cerebrovascular diseases is strong, mainly with stroke and cognitive impairment, but the mechanistic bases remain to be established. The objective of this study is to observe central blood pressure, arterial stiffness and intracranial pressure in long-term chronic hypertensive patients. Design and method: Patients above 18 years were assessed from November 2022 to August 2023 with non-invasive central blood pressure and intracranial pressure waveform measurements in a cross-sectional analysis. Peripheral and central blood pressure parameters were obtained using a validated oscillometric device (Mobil-O-Graph). Non-invasive intracranial pressure measurement was performed with the validated Brain4Care (B4C) sensor. Using the B4C non-invasive evaluation, the cut-off point identified to define ICHT by the P2/P1 ratio was > 1.2, and the cut-off for time to peak (TTP) was > 0.25 seconds. To compare P2/P1 and TTP values between the categories of quantitative variables, the chi-square test was used; the Mann Whitney or ANOVA tests were used for bivariate analyses; and for correlations, the Spearman test was used. It was adopted as significant at p < 0,05. Results: Non-invasive central blood pressure, arterial stiffness, and intracranial pressure waveform assessment were performed in 145 patients with essential long-term hypertension over a period of ten months. The median age was 69.0 (61.8 – 75.7) years, 77.9% were female, and the median BMI was 29.0 (25.4 – 33.1) kg/m2. The average time since the hypertension diagnosis was 20.0 years. The median value of P2/P1 ratio for all cohort was 1.4 (1.2 – 1.5) and TTP 0.24 (0.21 – 0.29) seconds. A bivariate analysis was performed considering ICHT or not and the parameters of central BP and PWV assessments, with findings of higher central SBP, central DBP, and peripheral DBP among patients with ICHT by the parameter of P2/P1. Conclusions: Central systolic blood pressure levels are more linked to intracranial hypertension, while diastolic blood pressure values are similar, raising questions about the most suitable blood pressure assessment method for brain disorders.

Preeclampsia-Associated Cardiovascular Risk Factors 6 Months and 2 Years After Pregnancy: The P4 Study.

Increased cardiovascular risk following preeclampsia is well established and there are signs of early cardiovascular aging 6 months postpartum. This study assessed whether blood pressure (BP) and other cardiovascular measures are abnormal 2 years postpartum in the same cohort to determine ongoing risk markers. Six months and 2 years postpartum, BP was measured using sphygmomanometry, 24-hour ambulatory BP monitoring, and noninvasive central BP. Anthropometric measures, blood, and urine biochemistry were performed. Cross-sectional comparisons between preeclampsia and normotensive pregnancy (NP) groups and longitudinal comparisons within each group were made at 6 months and 2 years. Two years postpartum, 129 NP, and 52 preeclampsia women were studied who also had 6 months measures. At both time points, preeclampsia group had significantly higher BP (office BP 2 years, 112±12/72±8 versus 104±9/67±7 mm Hg NP; [P<0.001]; mean ambulatory BP monitoring 116±9/73±8 versus 106±8/67±6 mm Hg NP; [P<0.001]). No significant BP changes noted 6 months to 2 years within either group. Office BP thresholds of 140 mm Hg systolic and 90 mm Hg diastolic classified 2% preeclampsia and 0% NP at 2 years. American Heart Association 2017 criteria (above normal, >120/80 mm Hg) classified 25% versus 8% (P<0.002), as did our reference range threshold of 122/79 mm Hg. American Heart Association criteria classified 60% post-preeclampsia versus 16% after NP with above-normal ambulatory BP monitoring (P<0.001). Other cardiovascular risk markers more common 2 years post-preeclampsia included higher body mass index (median 26.6 versus 23.1, P=0.003) and insulin resistance. After preeclampsia, women have significantly higher BP 6 months and 2 years postpartum, and have higher body mass index and insulin-resistance scores, increasing their future cardiovascular risk. Regular cardiovascular risk screening should be implemented for all who have experienced preeclampsia.

High Fidelity Pressure Wires Provide Accurate Validation of Non-Invasive Central Blood Pressure and Pulse Wave Velocity Measurements.

Central blood pressure (cBP) is known to be a better predictor of the damage caused by hypertension in comparison with peripheral blood pressure. During cardiac catheterization, we measured cBP in the ascending aorta with a fluid-filled guiding catheter (FF) in 75 patients and with a high-fidelity micromanometer tipped wire (FFR) in 20 patients. The wire was withdrawn into the brachial artery and aorto-brachial pulse wave velocity (abPWV) was calculated from the length of the pullback and the time delay between the ascending aorta and the brachial artery pulse waves by gating to the R-wave of the ECG for both measurements. In 23 patients, a cuff was inflated around the calf and an aorta-tibial pulse wave velocity (atPWV) was calculated from the distance between the cuff around the leg and the axillary notch and the time delay between the ascending aorta and the tibial pulse waves. Brachial BP was measured non-invasively and cBP was estimated using a new suprasystolic oscillometric technology. The mean differences between invasively measured cBP by FFR and non-invasive estimation were -0.4 ± 5.7 mmHg and by FF 5.4 ± 9.4 mmHg in 52 patients. Diastolic and mean cBP were both overestimated by oscillometry, with mean differences of -8.9 ± 5.5 mmHg and -6.4 ± 5.1 mmHg compared with the FFR and -10.6 ± 6.3 mmHg and -5.9 ± 6.2 mmHg with the FF. Non-invasive systolic cBP compared accurately with the high-fidelity FFR measurements, demonstrating a low bias (≤5 mmHg) and high precision (SD ≤ 8 mmHg). These criteria were not met when using the FF measurements. Invasively derived average Ao-brachial abPWV was 7.0 ± 1.4 m/s and that of Ao-tibial atPWV was 9.1 ± 1.8 m/s. Non-invasively estimated PWV based on the reflected wave transit time did not correlate with abPWV or with atPWV. In conclusion, we demonstrate the advantages of a novel method of validation for non-invasive cBP monitoring devices using acknowledged gold standard FFR wire transducers and the possibility to easily measure PWV during coronary angiography with the impact of cardiovascular risk factors.

Central blood pressure estimation in type 1 diabetes: impact and implications of peripheral calibration method.

Peripheral blood pressure (BP) waveforms are used for noninvasive central BP estimation. Central BP could assist in cardiovascular risk assessment in patients with type 1 diabetes mellitus (T1DM). However, correct calibration of peripheral BP waveforms is important to accurately estimate central BP. We examined differences in central BP estimated by radial artery tonometry depending on which brachial BP (SBP/DBP vs. MAP/DBP) is used for calibration of the radial waveforms, for the first time in T1DM. A cross-sectional study in T1DM patients without known cardiovascular disease. Radial artery BP waveforms were acquired using applanation tonometry ( SphygmoCor ) for the estimation of central SBP, central pulse pressure (PP) and central augmentation pressure, using either brachial SBP/DBP or MAP/DBP for the calibration of the radial pressure waveforms. Fifty-four patients (age: 46 ± 9.5 years; T1DM duration: 27 ± 8.8 years) were evaluated. Central BP parameters were significantly higher when brachial MAP/DBP-calibration was used compared with brachial SBP/DBP-calibration (7.5 ± 5.04, 7.5 ± 5.04 and 1.5 ± 1.36 mmHg higher central SBP, central PP and central augmentation pressure, respectively, P < 0.001). In patients with T1DM, there are significant differences in central BP values estimated with radial artery tonometry, depending on the method used for calibration of the radial waveforms. Brachial MAP/DBP-calibration resulted in consistently higher central BP as compared to using brachial SBP/DBP, leading to patient re-stratification. Hence, the accuracy of noninvasive estimation of central BP by radial tonometry is dependent on calibration approach, and this problem must be resolved in validation studies using an invasive reference standard to determine which method best estimates true central BP.

Factors That May Impact the Noninvasive Measurement of Central Blood Pressure Compared to Invasive Measurement: The MATCHY Study.

Calibration affects central blood pressure (BP) estimation accuracy. Factors influencing the accuracy of noninvasive central BP measurement, type of calibration method implemented (systolic/diastolic BP or mean/diastolic BP), and type of BP measurement device used (devices using the transfer function method, directly measurement from the carotid artery, and the transfer function-like method), were investigated. Fifty participants (aged 62.4 ± 8.9 years) without overt heart diseases were recruited. Invasive aortic and radial BP was measured. Simultaneously, noninvasive central BP was measured using three types of devices. The mean invasive aortic BP was 127 ± 19/95 ± 14 mmHg. Noninvasive central BP tended to be slightly lower than invasive BP, though without statistical significance. The type of calibration method did not significantly influence the noninvasive cSBP measurements (p ≥ 0.24). Results from cuff-based devices were significantly lower than invasive measurements (p = 0.04). Multiple regression analyses showed that gender was significantly correlated with the accuracy of noninvasive cSBP measurement. In conclusion, noninvasive cSBP measurements are comparable to invasive measurements but might underestimate true cSBP. The type of device may affect the accuracy of measurement. Either of the two calibration methods is acceptable.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Accuracy Difference of Noninvasive Blood Pressure Measurements by Sex and Height

Women are at higher risk of cardiovascular events than men with similar blood pressure (BP). Whether this discrepancy in risk is associated with the accuracy of brachial cuff BP measurements is unknown. To examine the difference in brachial cuff BP accuracy in men and women compared with invasively measured aortic BP and to evaluate whether noninvasive central BP estimation varies with sex. This cross-sectional study enrolled 500 participants without severe aortic stenosis or atrial fibrillation from January 1 to December 31, 2019, who were undergoing nonurgent coronary angiography at a tertiary care academic hospital. Simultaneous measurements of invasive aortic BP and noninvasive BP. Sex differences in accuracy were determined by calculating the mean difference between the noninvasive measurements (brachial and noninvasive central BP) and the invasive aortic BP (reference). Linear regression and mediation analyses were performed to identify mediators between sex and brachial cuff accuracy. This study included 500 participants (145 female [29%] and 355 male [71%]; 471 [94%] White; mean [SD] age, 66 [10] years). Baseline characteristics were similar for both sexes apart from body habitus. Despite similar brachial cuff systolic BP (SBP) (mean [SD], 124.5 [17.7] mm Hg in women vs 124.4 [16.4] in men; P = .97), invasive aortic SBP was higher in women (mean [SD], 130.9 [21.7] in women vs 124.7 [20.1] mm Hg in men; P < .001). The brachial cuff was relatively accurate compared with invasive aortic SBP estimation in men (mean [SD] difference, -0.3 [11.7] mm Hg) but not in women (mean [SD] difference, -6.5 [12.1] mm Hg). Noninvasive central SBP (calibrated for mean and diastolic BP) was more accurate in women (mean [SD] difference, 0.6 [15.3] mm Hg) than in men (mean [SD] difference, 8.3 [14.2] mm Hg). This association of sex with accuracy was mostly mediated by height (3.4 mm Hg; 95% CI, 1.1-5.6 mm Hg; 55% mediation). In this cross-sectional study, women had higher true aortic SBP than men with similar brachial cuff SBP, an association that was mostly mediated by a shorter stature. This difference in BP measurement may lead to unrecognized undertreatment of women and could partly explain why women are at greater risk for cardiovascular diseases for a given brachial cuff BP than men. These findings may justify the need to study sex-specific BP targets or integration of sex-specific parameters in BP estimation algorithms.

Isolated systolic hypertension is associated with increased left ventricular mass index and aortic stiffness in adolescents: a cardiac magnetic resonance study.

Despite the high prevalence of isolated systolic hypertension (ISH) among hypertensive adolescents, its clinical significance is not determined. In addition, it is hypothesized that ISH with normal central blood pressure (BP) in young patients is a benign phenomenon and was hence labeled spurious hypertension (sHTN). Using cardiac magnetic resonance we evaluated a group of 73 patients with suspected primary hypertension, aged 13-17 years (median: 16.9, interquartile range 15.8-17.4; 13 girls), in whom, based on 24-h ambulatory BP monitoring either ISH (n = 30) or white-coat hypertension (WCH) (n = 43) was diagnosed. Based on noninvasive central BP measurement 13 participants in the ISH group were classified as having sHTN and 17 were diagnosed with true hypertension. Compared with WCH adolescents, ISH patients presented with higher indexed left ventricular mass index (LVMI) (P < 0.001), maximal left ventricular (LV) wall thickness (P < 0.001), LV concentricity (P = 0.001) and more often had LV hypertrophy (47 vs. 14%, P = 0.002). They had higher average pulse wave velocity (PWV) in the proximal aorta (P = 0.016) and the whole thoracic aorta (P = 0.008). In addition, we observed higher indexed LV stroke volume (P = 0.025) in patients with ISH. The sHTN subgroup had significantly higher LVMI and aortic PWV, and more often had LV hypertrophy compared with the WCH group. The sHTN and true hypertension subgroups did not differ in terms of aortic PWV, LVMI or LV geometry. Compared with adolescents with WCH patients with ISH, including the sHTN subtype, have more pronounced markers of cardiac end-organ damage, higher aortic stiffness and stroke volume.

Relationship between noninvasive central blood pressure and brain natriuretic peptide levels in patients with hypertensive pulmonary edema.

Hypertensive pulmonary edema is a fatal condition unless early and properly diagnosed and managed. Central blood pressure (cBP) has been proven to be more associated with adverse cardiovascular events. We aimed to study the correlation between cBP and heart damage in patients with Hypertensive pulmonary edema. We included 50 patients admitted to the emergency department in a university hospital for hypertensive pulmonary edema, 27 women and 23 men aged 50 to 70 years. We excluded patients with suspected acute coronary syndrome, significant valvular heart disease, and pericardial diseases. We measured cBP non-invasively from pulse wave analysis of the brachial artery. Brain natriuretic peptide (BNP) and cBP were repeatedly measured for every patient. The median BNP levels of patients significantly decreased from 284 pg/ml (232-352.5) to 31.5 pg/ml (24-54) on discharge, P < 0.001. We found a significant correlation between admission BNP and central SBP (cSBP), urea, creatinine, arterial blood gases parameters, and left ventricular end-diastolic diameter (LVEDD). Concurrently, BNP at discharge was correlated with age, central DBP (cDBP), urea, creatinine, LVEDD, partial oxygen pressure (pO2), and oxygen saturation (SO2). Delta BNP was correlated with cSBP, peripheral SBP, urea, creatinine, pO2, and SO2. Linear regression analysis revealed that creatinine, and cSBP, were independent predictors of admission BNP, while urea and cDBP were the independent predictors of discharge BNP. This simple, noninvasive method of cBP measurement was significantly associated with the extent of myocardial damage in patients presenting with hypertensive pulmonary edema.

The predictive value of central aortic blood pressure on new onset stroke and differences between brachial blood pressure in a Chinese hypertensive population, a prospective cohort study

Abstract Objectives This study aimed to investigate the association between noninvasive central aortic blood pressure and the risk of first stroke in a Chinese community–based population, meanwhile compare the prediction ability of central SBP and peripheral SBP. Methods A total of 8473 Chinese participants without history of stroke and atrial fibrillation at baseline were selected from “Hypertension and Stroke Prevention and Control Project” for analysis. The endpoint of the study was first total stroke and stroke subtypes (ischemic stroke and hemorrhagic stroke). Cox proportional hazards regression, smoothing curve fitting, subgroup analysis, and Kaplan-Meier curve were used to analysis the relationship between central/peripheral systolic blood pressure and first stroke. Results Participants were 60.9±9.6 years old, 63.5% were males, and 96.1% had hypertension. After a mean 3.3-year follow-up, the incidence of first total stroke, first ischemic stroke and first hemorrhagic stroke were 5.1%, 4.6%, and 0.5%, respectively. In multivariate logistic-regression analyses, central and peripheral SBP were both independently associated with first total stroke and first ischemic stroke after adjusting for various confounders. Peripheral SBP's significant association with first total and ischemic stroke disappeared when combined analyzed with central SBP, whereas central SBP was still significantly related with first total and ischemic stroke after adjustment of peripheral SBP. For first hemorrhagic stroke, no significant differences were observed between central SBP and peripheral SBP. Subgroup analysis showed that the central SBP-first stroke association was significantly stronger in males (HR: 1.38; 95% CI: 1.16, 1.63) than in females (HR: 1.10; 95% CI: 0.97, 1.24; P-interaction = 0.028). Conclusions Among the Chinese community–based population, central SBP is a stronger predictor compared with peripheral SBP for first stroke, especially ischemic stroke. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Key R&amp;D Projects, JiangxiOutstanding Person Foundation

Comparison between invasive and non-invasive assessment of blood pressure in hypertensive disorders of pregnancy

BackgroundThe management of hypertensive disorders of pregnancy (HDP) during hospitalization requires an accurate blood pressure (BP) measurement, mainly by invasive intra-arterial reading. Nevertheless, little is known about the precision of non-invasive (NI) central BP measurements in HDP. We aimed to assess the accuracy of NI central BP assessment in comparison to invasive BP measurement in HDP.This cross-sectional study included all patients with HDP that were admitted to university hospitals for high BP control, from December 2018 till December 2019, and 10 healthy matched non-hypertensive controls. Patients were compared for demographic, anthropometric, and echocardiographic data. In all subjects, invasive BP assessment was done by radial arterial cannulation and NI assessment of BP was performed by an oscillometric automated device (Mobil-O-Graph); the comparison was done after initial control of BP.ResultsOne hundred patients were included and divided into 3 groups (pre-existing hypertension (HTN), gestational HTN, and pre-eclampsia). There was no statistically significant difference between NI central and invasive methods in measuring both systolic BP (SBP) (126.39 ± 14.5 vs 127.43 ± 15.3, p = 0.5) and diastolic BP (82.41 ± 9.0 vs 83.78 ± 8.9, p = 0.14) among the total studied population. A strong positive correlation was found between NI central and invasive SBP (r = 0.96, p < 0.001). HDP was associated with an increase in arterial stiffness, left ventricular diastolic dysfunction, and complications.ConclusionNon-invasive measurement of BP using oscillometric automated devices is as accurate as the invasive method, and it is a practical safe method in pregnant women with hypertensive disorders (CTR no. = NCT04303871).

A novel electrical impedance function to estimate central aortic blood pressure waveforms

Background and objectiveCentral aortic blood pressure waveforms convey imperative information about cardiovascular risk, but these measurements are obtained invasively. The study aims to develop an electrical impedance function (EIF) to estimate the central (aortic) blood pressure waveform from the radial blood pressure waveform without the need of invasive procedures. MethodsThis paper shows a method of using the four-element Windkessel model to derive an EIF using circuit analysis to estimate the central aortic blood pressure. The four elements were identified from radial waveforms by using the Nelder-Mead simplex algorithm and then used to construct the EIF to obtain the aortic pressure waveform, given the radial waveform. ResultsWaveforms generated by EIF gave the lowest values for Root Mean Square Error (RMSE) (5.69) and Mean Average Percentage Error (MAPE) (0.0402) compared to the generalized transfer function (GTF) and N-point moving average (NPMA), and the lowest MAPE and a comparable RMSE when compared to the Adaptive Transfer Function (ATF). Moreover, EIF has a significantly lower computing time (0.008 ms) when compared with GTF, NPMA and ATF. ConclusionsThe proposed function had comparable or better performance to existing methods when tested on both simulated and actual patient data, and was able to give a better signal shape retention at the dicrotic notch (99.94 % correlation), which is a crucial feature for cardiovascular disease detection. SignificanceOverall the EIF performance validates its use in estimating central aortic pressure waveforms, making it potentially viable for better embedded systems for non-invasive central blood pressure monitoring due to its low computation time and high accuracy.

Pulsatile and resistive systolic loads as determinants of left ventricular remodelling after physical training

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation Barts Cardiovascular Biomedical Research Centre onbehalf The Marathon Study Consortium Introduction Cardiovascular function depends on the inter-relation between heart and vasculature. The contribution of aorta and peripheral vessels to the total systolic load of the left ventricle (LV) can be represented respectively by a "pulsatile" and a "resistive" component. We sought to understand their interrelation by exploring how LV remodelling occurred with altered load associated with an external stimulus (training). Methods: 237 untrained healthy male and female subjects volunteering for their first-time marathon were recruited. At baseline and after 6 months of unsupervised training, race completers underwent 1.5T cardiac magnetic resonance, brachial and non-invasive central blood pressure assessment. For analysis, runners were divided into 4 groups according to the variation (positive versus null or negative) in Total Arterial Compliance Index (TACi), representing the pulsatile component of the LV load, and in Systemic Vascular Resistance Index (SVRI), representing the resistive component of the LV load. Results: 138runners (age 21-69 years; F: 51%) completed the race. Data are reported for each variable as Δ mean [95% Confidence Interval]. In the whole cohort, training was associated with a small increase in LV mass index (+3g/m2, [0, 6 g/m2]), indexed LV end-diastolic volume (EDVi) (+3ml/m2, [-2, 5 3ml/m2]), in LV mass/LVEDV ratio (+0.02g/ml, [0.00, 0.04 g/ml]) and in TACi (+0.02ml/m2, [0.02, 0.38 ml/m2]). SVRi mildly fell (-43dyn·s/cm2[-103, 17dyn·s/cm2]). TACi increase was associated with LVEDVi increase and no change in LV mass/EDV (eccentric remodelling). On the other hand, both TACi reduction and SVRi increase were associated with increase in LV mass/EDV and no significant change in LVEDVi (concentric remodelling). A similar increase in LV mass was observed in all groups. See Table. Conclusion: Cardiac remodelling observed after mild, medium term, unsupervised training seems to be related to the modifications of aorta and peripheral vessels. In particular, a reduction in pulsatile load seems associated with eccentric LV remodelling, while an increase in both pulsatile and resistive with concentric LV remodelling. Further research is needed to understand the interaction between TACi and SVRi. Table 1 LV EDVi (ml/m2) LV mass index (g/m2) LV mass/EDV TACi increase (n = 75) +4 [0, 9] +3 [0, 7] 0 [-0.03, 0.03] TACi decrease (n = 62) -1 [-6, 4] +3 [0, 8] 0.04 [0.01, 0.07] SVRi increase (n = 63) 0 [-4,4] +3 [0, 7] +0.03 [0, 0.06] SVRi decrease (n = 73) +3 [-3, 7] +3 [-1, 6] +0.01 [-0.02, 0.04]

Automated Noninvasive Central Blood Pressure Measurements by Oscillometric Radial Pulse Wave Analysis: Results of the MEASURE-cBP Validation Studies.

Central blood pressure becomes increasingly accepted as an important diagnostic and therapeutic parameter. Accuracy of widespread applanation tonometry can be affected by calibration and operator training. To overcome this, we aimed to evaluate novel VascAssist 2 using automated oscillometric radial pulse wave analysis and a refined multi-compartment model of the arterial tree. Two hundred and twenty-five patients were prospectively enrolled. Invasive aortic root measurements served as reference in MEASURE-cBP 1 (n = 106) whereas applanation tonometry (SphygmoCor) was used in MEASURE-cBP 2 (n = 119). In MEASURE-cBP 1, we found a mean overestimation for systolic values of 4 ± 12 mmHg (3 ± 10%) and 6 ± 10 mmHg (9 ± 14%) for diastolic values. Diabetes mellitus and low blood pressure were associated with larger variation. In MEASURE-cBP 2, mean overestimation of systolic values was 4 ± 4 mmHg (4 ± 4%) and 1 ± 4 mmHg (1 ± 7%) of diastolic values. Arrhythmia was significantly more frequent in invalid measurements (61 vs. 18%, P < 0.0001) which were most often due to a low quality index of SphygmoCor. Central blood pressure estimates using VascAssist 2 can be considered at least as accurate as available techniques, even including diabetic patients. In direct comparison, automated measurement considerably facilitates application not requiring operator training and can be reliably applied even in patients with arrhythmias.

4-8CENTRAL AORTIC SYSTOLIC PRESSURE MEASUREMENT IN PATIENTS WITH REFRACTORY HYPERTENSION

Background: Aortic systolic pressure is regarded more reliable due to elastic properties of the central arterial walls, than the peripheral blood pressure (BP) brachial arteries being more muscular. The arterial distensibilty is an important factor in determining the vascular age and predicting future acute aortic events. The non-invasive central blood pressure can aid in early detection and harmonising treatment in patients with Refractory hypertension (RH). Aim: To assess the Central aortic systolic pressure (CASP) in RH patients. Methods and materials: We identified 111 patients with refractory hypertension (uncontrolled BP despite use of 3 or more anti-hypertensives) at the outpatient clinic of Kasturba Medical College Hospital, Mangalore in the period of July-August 2018. The non-invasive CASP, Average systolic, diastolic and pulse (AvgS, AvgD, AvgP) measured with A-PULSE CASPal® Monitoring Device. Statistical analysis using SPSS software and parameters like Independent t-test, descriptive statistics (mean, standard deviation) were calculated. Results: The average age of the patients was 58 ± 14.95; 39 (35.1%) were females(F) and 72 (64.9%) were males (M). There was a significant difference in the CASP in F 146.6 ± 29.34 and 139.6 ± 21.8 in M; AvgS in F and M was 157.9 ± 28 and 152.4 ± 21.8 respectively. AvgD and AvgP in F and M were 92.9 ± 17.1, 92.5 ± 13.3 and 83.87 ± 13.9, 79.2 ± 13.6 respectively. Conditions age and CASP p = 0.324; age and AvgS p = 0.338; CASP and AvgS p = 0.919 were significant at p &lt; 0.01. Conclusions: In patients with refractory hypertension, chrono-modulation with centrally acting anti-hypertensive drugs and synchronous CASP monitoring non-invasively can predict early target organ damage and helps improve the quality of life.

New Model for Non-Invasive Echocardiographic Assessment of Pulmonary-Capillary Wedge Pressure in Patients With Aortic and Mitral Regurgitation

The pulmonary-capillary wedge pressure (PCWP) is a central parameter of cardiac function. In this work, we propose an equation based on a simple physical model, which should be applicable to any class of patient, provided they present some level of aortic and mitral regurgitation. We modeled the left cardio-circulatory system as three chambers placed in a series as follows: left atrium (LA), left ventricle (LV), and aorta (A). Starting from the principle of energy conservation, knowing pressure gradient between A and LV (transaortic gradient) and between LV and LA (trans mitral gradient), we can measure blood pressure in A with a non-invasive central blood pressure (BP) analysis device and then we can derive pressure in LA. With the model described, we derive the equation PCWP ≈ {[(systolic central BP + 4 maximal aortic valve outflow velocity2) − 4 maximal mitral valve regurgitation jet velocity2] + [(diastolic central BP − 4 telediastolic aortic valve regurgitation jet velocity2) + mean mitral valve inflow gradient]} / 2. Herein, we propose a new model for PCWP determination using Doppler echocardiography and a non-invasive central blood pressure (BP) analysis device. One of the main advantages of the method we proposed is that, given it is based on a simple physical model instead of multilinear regression, it should be applicable to any class of patient, provided they present some level of aortic and mitral regurgitation. Further studies are needed for its validation by parallel analysis using invasive methods.

Age matters: differences in exercise-induced cardiovascular remodelling in young and middle aged healthy sedentary individuals

Remodelling of the cardiovascular system (including heart and vasculature) is a dynamic process influenced by multiple physiological and pathological factors. We sought to understand whether remodelling in response to a stimulus, exercise training, altered with healthy ageing. A total of 237 untrained healthy male and female subjects volunteering for their first time marathon were recruited. At baseline and after 6 months of unsupervised training, race completers underwent tests including 1.5T cardiac magnetic resonance, brachial and non-invasive central blood pressure assessment. For analysis, runners were divided by age into under or over 35 years (U35, O35). Injury and completion rates were similar among the groups; 138 runners (U35: n = 71, women 49%; O35: n = 67, women 51%) completed the race. On average, U35 were faster by 37 minutes (12%). Training induced a small increase in left ventricular mass in both groups (3 g/m2, P < 0.001), but U35 also increased ventricular cavity sizes (left ventricular end-diastolic volume (EDV)i +3%; left ventricular end-systolic volume (ESV)i +8%; right ventricular end-diastolic volume (EDV)i +4%; right ventricular end-systolic volume (ESV)i +5%; P < 0.01 for all). Systemic aortic compliance fell in the whole sample by 7% (P = 0.020) and, especially in O35, also systemic vascular resistance (-4% in the whole sample, P = 0.04) and blood pressure (systolic/diastolic, whole sample: brachial -4/-3 mmHg, central -4/-2 mmHg, all P < 0.001; O35: brachial -6/-3 mmHg, central -6/-4 mmHg, all P < 0.001). Medium-term, unsupervised physical training in healthy sedentary individuals induces measurable remodelling of both heart and vasculature. This amount is age dependent, with predominant cardiac remodelling when younger and predominantly vascular remodelling when older.

Observer-Based Deconvolution of Deterministic Input in Coprime Multichannel Systems With Its Application to Noninvasive Central Blood Pressure Monitoring.

Estimating central aortic blood pressure (BP) is important for cardiovascular (CV) health and risk prediction purposes. CV system is a multichannel dynamical system that yields multiple BPs at various body sites in response to central aortic BP. This paper concerns the development and analysis of an observer-based approach to deconvolution of unknown input in a class of coprime multichannel systems applicable to noninvasive estimation of central aortic BP. A multichannel system yields multiple outputs in response to a common input. Hence, the relationship between any pair of two outputs constitutes a hypothetical input-output system with unknown input embedded as a state. The central idea underlying our approach is to derive the unknown input by designing an observer for the hypothetical input-output system. In this paper, we developed an unknown input observer (UIO) for input deconvolution in coprime multichannel systems. We provided a universal design algorithm as well as meaningful physical insights and inherent performance limitations associated with the algorithm. The validity and potential of our approach were illustrated using a case study of estimating central aortic BP waveform from two noninvasively acquired peripheral arterial pulse waveforms. The UIO could reduce the root-mean-squared error (RMSE) associated with the central aortic BP by up to 27.5% and 28.8% against conventional inverse filtering (IF) and peripheral arterial pulse scaling techniques.

Influence of noninvasive central blood pressure devices for afterload monitoring with aortic velocity-pressure Loop in anesthetized patients.

Global afterload angle (GALA) is a parameter derived from velocity-pressure loop (VP Loop), for continuous assessment of cardiac afterload in the operating room. It has been validated with invasive measure of central pressure. The aim of this study was to evaluate the feasibility of noninvasive VP Loop obtained with central pressure measured with two different noninvasive tonometers. A prospective, observational, monocentric study was conducted in 51 patients under general anesthesia. Invasive central pressure (cPINV) was measured with a fulfilled intravascular catheter, and noninvasive central pressure signals were obtained with two applanation tonometry devices: radial artery tonometry (cPSHYG: Sphygmocor tonometer) and carotid tonometry (cPCOMP: Complior tonometer). Three VP Loops were built: VP LoopINV, VP LoopSPHYG and VP LoopCOMP. Patients were separated according to cardiovascular risk factors. In the 51 patients under general anesthesia, cPSHYG was adequately obtained in 48 patients (89%) but, compared to cPINV, SBP was underestimated (-4 ± 6 mmHg, P < 0.0001), augmentation index (AIXSPHYG) and a GALASPHYG were overestimated (+13 ± 19%, P = 0.0077 and +4 ± 8°, P = 0.0024, respectively) with large limit of agreement (LOA) (-21 to 47% and -13 to 21° for AIXSPHYG and GALASPHYG, respectively). With the Complior, the failure rate of measurement for cPCOMP was 41%. SBP was similar (3 ± 17 mmHg, P = 0.32), AIXCOMP was underestimated (-11 ± 19%, P = 0.0046) and GALACOMP was similar but with large LOA (-50 to 26% and -20 to 18° for AIXCOMP and GALACOMP, respectively). In anesthetized patient, the reliability of noninvasive central pressure monitoring by tonometry seems too limited to monitor cardiac afterload with VP Loop.

MON-LB52 Evaluation of Arterial Stiffness in Acromegaly Patients

Acromegaly is associated with increased morbidity and mortality primarily attributed to cardiovascular and cerebrovascular diseases, thus demonstrating the negative arterial impact of chronic GH and IGF-1 excess. There are limited and conflicting data regarding coronary artery disease (CAD) in acromegaly that consists mainly of heterogeneous cohorts and pathological reviews of old case series. Increased arterial stiffness is associated with an increased risk of cardiovascular events such as myocardial infarction. Arterial stiffness may measured from pulse wave velocity(PWV). In this study we aimed to evaluate the association between pulse wave velocity and aortic augmentation index in acromegalic patients. Methods: Our study population consists of a consecutive subset of 32 acromegalic patients and 19 control. Acromegalic patients IGF 1 levels were noted. All patients BMI, age, blood pressure, gender also were noted. Also pulse pressure, central blood pressures were measured by non-invasive central blood pressure measurement device (SphygmoCor). Pulse wave velocity and aortic augmentation index were measured by the same device. Results: A total of 32 acromegalic patients and 19 control were enrolled in the study. Body mass index and gender were not significantly different between the groups. Aortic augmentation index (5 vs. 6, p =0,685) variables weren’t significantly different in the study. Systolic and diastolic blood pressures were significantly high in the acromegalic group. (130/82 vs. 120/70) PWV was significantly high in the acromegalic group. (13 vs 11,5 p=0,002)Conclusions: Our study results suggest that acromegaly patients have worse arterial stiffness due to increased pulse wave velocity. Acromegaly is associated with increased morbidity and mortality primarily attributed to cardiovascular problems. We thought that it may be a guiding method in disease management since it can be an early marker of cardiovascular risk.Keywords: acromegaly, pulse wave velocity, aortic augmentation index