Improved diagnostic accuracy for hypertension

Practical and accurate blood pressure (BP) measurement techniques are needed to ensure adequate diagnostics and treatment of hypertension. Recently, novel monitors have appeared on the market including timer-equipped home monitors and standalone noninvasive central BP monitors. The aim of this study was to clarify how BP measures obtained with these novel measurement methods compare to current measurement methods, and whether they could improve the diagnostics for hypertensive end-organ damage compared with conventional measurements in a cardiovascular substudy (N=290) of the Finnish population-based DILGOM study. Participants underwent 24-hour ambulatorymonitoring, office BP measurements, and daytime and night-time home measurements. Hypertensive end-organ damage was assessed with pulse wave velocity (PWV) measurements, carotid intima-media thickness (IMT) and left ventricular mass index (LVMI). The participants preferred office BP measurement, while ambulatory monitoring was the least acceptable method. Mean night-time BP levels were comparable between ambulatory and home monitoring, and the agreement between the methods in detecting night-time hypertension was substantial. Instead, the agreement in detecting nondipping patterns was weak. Home and ambulatory night-time BP values correlated similarly with end-organ damage, except that there was a slightly stronger correlation between ambulatory systolic BP (SBP) and PWV compared with corresponding home BP. Surprisingly, we found that brachial SBP and pulse pressure were similarly or even more strongly correlated to end-organ damage than the corresponding noninvasive central measures. To conclude, home night-time monitoring is a convenient, accurate, wellaccepted and widely available alternative to ambulatory monitoring in detecting night-time hypertension. In comparison to measurements with conventional office BP, estimated central hemodynamics with a novel stand-alone monitor do not seem to improve the diagnostics of end-organ damage.Verenpaineen uudet mittausmenetelmät Kohonneen verenpaineen asianmukaista diagnosointia ja hoitoa tarvitaan käytännöllisiä ja tarkkoja mittausmenetelmiä. Useita uusia mittareita on ilmaantunut markkinoille, mukaan lukien ajastimella varustetut kotimittarit sekä mittarit, joilla pystytään arvioimaan kajoamattomasti sentraalista eli aortan ja suurten suonten verenpainetta. Väitöskirjan tarkoituksena oli selvittää, miten nämä uudet mittaustavat vertautuvat perinteisiin menetelmiin ja parantavatko ne kohde-elinvaurioiden diagnostiikkaa verrattuna perinteisiin menetelmiin suomalaisessa DILGOM-väestötutkimuksen sydän- ja verisuonitutkimusalaryhmässä (N=290). Tutkimushenkilöille tehtiin verenpaineen vuorokausirekisteröinti, mittaukset vastaanotolla sekä kotona päivä- ja yöaikaan. Verenpaineen pääte-elinvaurioiden arviointiin käytettiin pulssiaallon nopeutta, kaulasuonten intima-media paksuutta ja vasemman kammion massaindeksiä. Tutkittavat pitivät eniten verenpaineen mittaamisesta vastaanotolla ja vähiten verenpaineen vuorokausirekisteröinnistä. Vuorokausirekisteröinnillä ja kotimittarilla mitatut yölliset verenpainetasot vastasivat hyvin toisiaan ja yhteneväisyys yöllisen kohonneen verenpaineen diagnosoinnissa menetelmien välillä oli huomattavan hyvä. Sitä vastoin verenpaineen poikkeavan päivä-yövaihtelun diagnostinen yhteneväisyys menetelmien välillä oli heikko. Mittausmenetelmästä riippumatta yöllisen verenpaineen yhteys pääte-elinvaurioihin oli samankaltainen lukuun ottamatta pulssiaallon nopeutta, minkä yhteys vuorokausirekisteröinnin kanssa oli hieman kotimittausta vahvempi. Yllättäen olkavarresta mitattu verenpaine oli yhtä hyvin ja osin jopa vahvemmin yhteydessä pääte-elinvaurioihin kuin kajoamattomasti mitattu sentraalinen verenpaine. Yhteenvetona todetaan, että verenpaineen yöaikainen mittaus kotimittarilla on käytännöllinen, tarkka, miellyttävä ja laajasti saatavilla oleva vaihtoehto verenpaineen vuorokausirekisteröinnille yöaikaisen kohonneen verenpaineen todentamiseen. Kajoamattoman sentraalisen verenpaineen arvioiminen tutkimuksessa käytetyllä helppokäyttöisellä automaattimittarilla ei näytä tuovan lisäetua pääteelinvaurioiden diagnostiikassa tavanomaiseen vastaanotolla olkavarresta mitattuun verenpaineeseen verrattuna

The Noninvasive Measurement of Central Aortic Blood Pressure Waveform

Central aortic pressure (CAP) is a potential surrogate of brachial blood pressure in both clinical practice and routine health screening. It directly reflects the status of the central aorta. Noninvasive measurement of CAP becomes a crucial technique of great interest. There have been advances in recent years, including the proposal of novel methods and commercialization of several instruments. This chapter briefly introduces the clinical importance of CAP and the theoretical basis for the generation of CAP in the first and second sections. The third section describes and discusses the measurement of peripheral blood pressure waveforms, which is employed to estimate CAP. We then review the proposed methods for the measurement of CAP. The calibration of blood pressure waveforms is discussed in the fourth section. After a brief discussion of the technical limitations, we give suggestions for perspectives and future challenges

Pulse Wave Calibration and Implications for Blood Pressure Measurement: Systematic Review and Meta-Analysis

Central aortic systolic pressure (CASP) can be estimated via filtering of the peripheral pulse wave (PPW) following calibration to brachial blood pressure. Recent studies suggest PPW calibration to mean arterial pressure (MAP) and diastolic BP (DBP) provides more accurate CASP estimates (CASPMD) versus conventional calibration to systolic BP (SBP) and DBP (CASPSD). However, the peak of the MAP-DBP calibrated PPW, that is, SBPMD, is rarely reported or used for BP amplification calculations, despite CASPMD being derived from it. We aimed to calculate the unreported SBPMD from studies using MAP-DBP calibration for estimation of CASPMD and compared it with oscillometric brachial SBP (brSBP). Medline database was searched to March 18, 2020. Meta-analysis includes studies reporting noninvasive CASPSD, CASPMD, brSBP, and brachial DBP. SBPMD was calculated using linear function equations. Data from 21 studies used 8 different BP monitors (13 460 participants, mean age: 54±10 years, 57% female, brachial blood pressure: 130±14/79±9 mm Hg). Weighted mean difference between SBPMD and brSBP was 10 mm Hg (range, -2 to 17 mm Hg) and appeared device specific. Calibration of brachial versus radial PPWs to brachial blood pressure showed a greater disparity between SBPMD and brSBP (14 versus 2 mm Hg). BP amplification was similar comparing SBP-DBP versus MAP-DBP calibrations (brSBP-CASPSD versus SBPMD-CASPMD: 9 versus 11 mm Hg), with no instances of reverse BP amplification. PPWs calibrated to MAP-DBP to derive CASPMD generates SBPMD that differs markedly from brSBP with some oscillometric BP monitors. These findings have important implications for BP monitor accuracy, BP amplification, PPW calibration recommendations, and studies of associations between CASP versus SBP and outcomes

Twenty-Four-Hour Central (Aortic) Systolic Blood Pressure: Reference Values and Dipping Patterns in Untreated Individuals.

Central (aortic) systolic blood pressure (cSBP) is the pressure seen by the heart, the brain, and the kidneys. If properly measured, cSBP is closer associated with hypertension-mediated organ damage and prognosis, as compared with brachial SBP (bSBP). We investigated 24-hour profiles of bSBP and cSBP, measured simultaneously using Mobilograph devices, in 2423 untreated adults (1275 women; age, 18-94 years), free from overt cardiovascular disease, aiming to develop reference values and to analyze daytime-nighttime variability. Central SBP was assessed, using brachial waveforms, calibrated with mean arterial pressure (MAP)/diastolic BP (cSBPMAP/DBPcal), or bSBP/diastolic blood pressure (cSBPSBP/DBPcal), and a validated transfer function, resulting in 144 509 valid brachial and 130 804 valid central measurements. Averaged 24-hour, daytime, and nighttime brachial BP across all individuals was 124/79, 126/81, and 116/72 mm Hg, respectively. Averaged 24-hour, daytime, and nighttime values for cSBPMAP/DBPcal were 128, 128, and 125 mm Hg and 115, 117, and 107 mm Hg for cSBPSBP/DBPcal, respectively. We pragmatically propose as upper normal limit for 24-hour cSBPMAP/DBPcal 135 mm Hg and for 24-hour cSBPSBP/DBPcal 120 mm Hg. bSBP dipping (nighttime-daytime/daytime SBP) was -10.6 % in young participants and decreased with increasing age. Central SBPSBP/DBPcal dipping was less pronounced (-8.7% in young participants). In contrast, cSBPMAP/DBPcal dipping was completely absent in the youngest age group and less pronounced in all other participants. These data may serve for comparison in various diseases and have potential implications for refining hypertension diagnosis and management. The different dipping behavior of bSBP versus cSBP requires further investigation

Development, Validation, and Clinical Application of a Numerical Model for Pulse Wave Velocity Propagation in a Cardiovascular System with Application to Noninvasive Blood Pressure Measurements

High blood pressure blood pressure is an important risk factor for cardiovascular disease and affects almost one-third of the U.S. adult population. Historical cuff-less non-invasive techniques used to monitor blood pressure are not accurate and highlight the need for first principal models. The first model is a one-dimensional model for pulse wave velocity (PWV) propagation in compliant arteries that accounts for nonlinear fluids in a linear elastic thin walled vessel. The results indicate an inverse quadratic relationship (R^2=.99) between ejection time and PWV, with ejection time dominating the PWV shifts (12%). The second model predicts the general relationship between PWV and blood pressure with a rigorous account of nonlinearities in the fluid dynamics, blood vessel elasticity, and finite dynamic deformation of a membrane type thin anisotropic wall. The nonlinear model achieves the best match with the experimental data. To retrieve individual vascular information of a patient, the inverse problem of hemodynamics is presented, calculating local orthotropic hyperelastic properties of the arterial wall. The final model examines the impact of the thick arterial wall with different material properties in the radial direction. For a hypertensive subject the thick wall model provides improved accuracy up to 8.4% in PWV prediction over its thin wall counterpart. This translates to nearly 20% improvement in blood pressure prediction based on a PWV measure. The models highlight flow velocity is additive to the classic pressure wave, suggesting flow velocity correction may be important for cuff-less, non-invasive blood pressure measures. Systolic flow correction of the measured PWV improves the R2 correlation to systolic blood pressure from 0.81 to 0.92 for the mongrel dog study, and 0.34 to 0.88 for the human subjects study. The algorithms and insight resulting from this work can enable the development of an integrated microsystem for cuff-less, non-invasive blood pressure monitoring

The International Database of Central Arterial Properties for Risk Stratification: Research Objectives and Baseline Characteristics of Participants

OBJECTIVE To address to what extent central hemodynamic measurements, improve risk stratification, and determine outcome-based diagnostic thresholds, we constructed the International Database of Central Arterial Properties for Risk Stratification (IDCARS), allowing a participant-level meta-analysis. The purpose of this article was to describe the characteristics of IDCARS participants and to highlight research perspectives. METHODS Longitudinal or cross-sectional cohort studies with central blood pressure measured with the SphygmoCor devices and software were included. RESULTS The database included 10,930 subjects (54.8% women; median age 46.0 years) from 13 studies in Europe, Africa, Asia, and South America. The prevalence of office hypertension was 4,446 (40.1%), of which 2,713 (61.0%) were treated, and of diabetes mellitus was 629 (5.8%). The peripheral and central systolic/diastolic blood pressure averaged 129.5/78.7 mm Hg and 118.2/79.7 mm Hg, respectively. Mean aortic pulse wave velocity was 7.3 m per seconds. Among 6,871 participants enrolled in 9 longitudinal studies, the median follow-up was 4.2 years (5th–95th percentile interval, 1.3–12.2 years). During 38,957 person-years of follow-up, 339 participants experienced a composite cardiovascular event and 212 died, 67 of cardiovascular disease. CONCLUSIONS IDCARS will provide a unique opportunity to investigate hypotheses on central hemodynamic measurements that could not reliably be studied in individual studies. The results of these analyses might inform guidelines and be of help to clinicians involved in the management of patients with suspected or established hypertension

Detecting Vital Signs with Wearable Wireless Sensors

The emergence of wireless technologies and advancements in on-body sensor design can enable change in the conventional health-care system, replacing it with wearable health-care systems, centred on the individual. Wearable monitoring systems can provide continuous physiological data, as well as better information regarding the general health of individuals. Thus, such vital-sign monitoring systems will reduce health-care costs by disease prevention and enhance the quality of life with disease management. In this paper, recent progress in non-invasive monitoring technologies for chronic disease management is reviewed. In particular, devices and techniques for monitoring blood pressure, blood glucose levels, cardiac activity and respiratory activity are discussed; in addition, on-body propagation issues for multiple sensors are presented

Wearable technology and the cardiovascular system: the future of patient assessment

The past decade has seen a dramatic rise in consumer technologies able to monitor a variety of cardiovascular parameters. Such devices initially recorded markers of exercise, but now include physiological and health-care focused measurements. The public are keen to adopt these devices in the belief that they are useful to identify and monitor cardiovascular disease. Clinicians are therefore often presented with health app data accompanied by a diverse range of concerns and queries. Herein, we assess whether these devices are accurate, their outputs validated, and whether they are suitable for professionals to make management decisions. We review underpinning methods and technologies and explore the evidence supporting the use of these devices as diagnostic and monitoring tools in hypertension, arrhythmia, heart failure, coronary artery disease, pulmonary hypertension, and valvular heart disease. Used correctly, they might improve health care and support research