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Siegfried Wassertheurer

Siegfried Wassertheurer
AIT Austrian Institute of Technoogy, Vienna, Austria · Department Health & Environment

MSc, PhD

About

255
Publications
18,818
Reads
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3,616
Citations
Additional affiliations
April 2003 - present
AIT Austrian Institute of Technology
Position
  • Head of Department
January 2003 - present
TU Wien
Position
  • Lecturer

Publications

Publications (255)
Article
Heart failure with reduced ejection fraction (HFrEF) is a significant health problem. Early diagnosis, using widely available, cheap methods, remains an important goal. Therefore, we investigated whether individuals with normal left ventricular ejection fraction (EF) can be discriminated from patients with reduced EF with contemporary, automated an...
Article
There is evidence that device guided slow breathing using biofeedback acutely reduces blood pressure (BP) and pulse wave velocity (i.e., increases pulse arrival time) from own prior studies and from the literature. The objectives of the study presented here were to test whether the results of changes observed in pulse arrival time in earlier studie...
Article
Full-text available
Background: Renal denervation (RDN) lowers blood pressure (BP), but BP response is variable in individual patients. We investigated whether measures of pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, predict BP drop following RDN. Methods: From the randomized, sham-controlled SPYRAL HTN-OFF MED Pivotal trial, we perform...
Article
Full-text available
Attractor reconstruction is a new way to quantify the morphology of a cardiovascular waveform by plotting all data points in the three-dimensional phase space, generating a trajectory of overlapping loops. The aim of this study is to show the feasibility of an automatic approach to quantify pulse wave attractors from a device-guided breathing study...
Article
Full-text available
Background Absolute blood volume (ABV) is a critical component of fluid status, which may inform target weight prescriptions and hemodynamic vulnerability of dialysis patients. Here, we utilized the changes in relative blood volume (RBV), monitored by ultrasound (BVM) upon intradialytic 240 mL dialysate fluid bolus-infusion 1 h after hemodialysis s...
Chapter
Measurements of arterial stiffness and pulsatile hemodynamics undoubtedly led to enormous progress in our understanding of cardiovascular physiology, aging, and development of diseases. Until very recently, these measurements were confined primarily to research laboratories and hospitals and less to the doctor's office. In contrast, we know from th...
Article
New findings: What is the central question of this study? First, we validated easy-to-use oscillometric left ventricular ejection time (LVET) against echocardiographic LVET. Second, we investigated progression of left ventricular ejection time index (LVETI), pre-ejection period index (PEPI), total electromechanical systole index (QS2I) and PEP/LVE...
Article
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 devic...
Article
Full-text available
Background: Atrial fibrillation (AF) is common in hemodialysis patients and contributes to increased mortality. We aimed to examine heart rate variability triangular index (HRVI) in hemodialysis patients with AF as it has recently been reported to predict mortality in AF patients without kidney disease. Methods: A total of 88 patients on hemodialys...
Article
Background Reservoir-wave analysis (RWA) separates the arterial waveform into reservoir and excess pressure (XSP) components, where XSP is analogous to flow and related to left ventricular workload. RWA provides more detailed information about the arterial tree than traditional blood pressure (BP) parameters. In end-stage renal disease (ESRD), we h...
Conference Paper
Background. Recent vascular biomarker studies indicate that long term space flight and head down tilt bed rest (HDTBR) might lead to premature vascular ageing. However, vascular ageing is a broad term and many different vascular biomarkers are currently used. Therefore, attention must be paid to the specific type of biomarker and its recording site...
Article
Full-text available
Background: In hemodialysis patients, left ventricular hypertrophy (LVH) contributes to high cardiovascular mortality. We examined cardiovascular mortality prediction by the recently proposed Peguero-Lo Presti voltage since it identifies more patients with electrocardiographic (ECG) LVH than Cornell or Sokolow-Lyon voltages. Methods: A total of...
Article
Full-text available
Background Cardiovascular risk may be increased in astronauts after long term space flights based on biomarkers indicating premature vascular aging. We tested the hypothesis that 60 days of strict 6° head down tilt bed rest (HDTBR), an established space analog, promotes vascular stiffening and that artificial gravity training ameliorates the respon...
Article
Aortic pulse wave velocity (PWV) is directly related to arterial stiffness. Different methods for the determination of PWV coexist. The aim of this prospective study was to evaluate the prognostic value of PWV in high-risk patients with suspected coronary artery disease undergoing invasive angiography and to compare 3 different methods for assessin...
Article
Introduction: Microgravity in space is known to cause major alterations in the cardiovascular system. Left ventricular ejection time (LVET) can be measured by the time from the onset point of the pressure wave to the incisura of the dicrotic notch. The aim of this study was to simulate microgravity by head-down tilt bedrest (HDT) to examine changes...
Article
Background Vascular aging, defined by aortic pulse wave velocity (aoPWV), as well as coronary artery calcium (CaC), are emerging risk predictors. Purpose To investigate the prognostic role of functional (vascular aging) and structural (CaC) arterial parameters in individuals without established cardiovascular disease. Methods We utilized our rece...
Article
Heart failure (HF), hypertension, and abnormal nocturnal blood pressure dipping are highly prevalent in hemodialysis patients. Atrial fibrillation (AF) and HF might be important mediators for the association of abnormal dipping patterns with worse prognosis. Thus, the aim of this study is to investigate the association of dipping with mortality in...
Article
Full-text available
Objective: Slow breathing is a relaxation exercise recommended for lowering blood pressure (BP). Biofeedback may improve patient adherence and enhance BP lowering effects. Since the pulse arrival time (PAT) is inversely proportional to BP, it can be used to estimate BP changes. Approach: In this pilot study, 30 patients (age 62.9 (SD 7.7) years,...
Article
Re-reflections of arterial pressure waves at the aortic valve and their influence on aortic wave shape are only poorly understood so far. Therefore, the aim of this work is to establish a model enabling the simulation of re-reflection and to test its properties. A mathematical difference equation model is used for the simulations. In this model, th...
Conference Paper
Arterial stiffness is an important indicator for vascular aging and an independent predictor for cardiovascular diseases. During space flights or simulated space flights by prolonged head-down tilt bed rest, major cardiovascular alterations occur. However, the changes in arterial stiffness are not fully understood yet. Thus, we aimed to develop a s...
Article
Full-text available
Cardiovascular mortality is the leading cause of death in Austria, with uncontrolled blood pressure (BP) as a major risk factor. Increased arterial stiffness can indicate high cardiovascular risk. In a screening project, we acquired brachial waveforms with automated oscillometric devices in 45 public pharmacies and at 2 public health events in Uppe...
Article
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Background: Steady state hemodynamics [Stroke Volume - SV, cardiac output, peripheral resistance (Rp)] have attracted researchers in hypertension for decades. However, due to technical difficulties, they never entered clinical medicine. Objective: To investigate the performance of a model-based algorithm, utilizing brachial pressure waveforms obtai...
Article
Full-text available
Background Excess mortality in hemodialysis patients is mostly of cardiovascular origin. We examined the association of heart rate turbulence (HRT), a marker of baroreflex sensitivity, with cardiovascular mortality in hemodialysis patients.MethodsA population of 290 prevalent hemodialysis patients was followed up for a median of 3 years. HRT catego...
Article
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Introduction: Arterial properties are linked to the presence and severity of coronary artery disease (CAD). Coronary blood flow is strongly and inversely related to arterial stiffness. Thus, the aim of this prospective study was to evaluate the prognostic value of PWV in high-risk patients with suspected CAD and to compare three different methods f...
Article
Full-text available
Purpose/Background/Objectives: According to reservoir-wave theory, excess pressure (XSP) is analogous to flow and related to excess cardiac workload. In end-stage renal disease (ESRD) patients, we have shown that XSPI is associated with increased mortality and is higher in patients with arteriovenous fistula (AVF). Recently AVF has been proposed tr...
Article
Full-text available
Introduction: The concept of re-reflections of blood pressure waves at the heart has been neglected in most models and is only poorly understood so far. Therefore, the aim of this work was to develop a simple mathematical model which is capable to represent the effects of wave travel, wave reflection as well as re-reflection at the aortic valve. Me...
Article
Full-text available
Background: There is evidence of a closer relation between 24 hour aortic systolic blood pressure (aSBP) and left ventricular mass (LVM) compared with 24 hour brachial SBP. However, sample sizes are relatively small and there is some inconsistency in findings. We sought to address this by pooling data from 16 centers in Asia, Europe and Latin Ameri...
Conference Paper
Full-text available
Background Changes in large artery properties including increased arterial compliance and increased carotid artery stiffness have been described after space flight. Altered vascular structure, which heralds cardiovascular risk, and reversible changes in vascular function could contribute to the response. Compared with previous studies, which did no...
Article
Objectives: Hemodialysis patients have premature arterial stiffness, and the relationship between pulse wave velocity (PWV) and blood pressure (BP) may be different than in other hypertensives. Previous studies in such patients showed that when BP decrease is accompanied by PWV decrease the survival is improved. This study examines the prognostic...
Article
The Ankle Brachial Index (ABI) is the most commonly used method for the investigation of peripheral artery disease (PAD) in clinical settings, but has a low sensitivity for detecting PAD in asymptomatic patients. It is calculated only based on the systolic blood pressure in the limbs and ignores the shape of the pressure waves. Therefore, we invest...
Article
Introduction and purpose Hemodialysis patients have premature arterial stiffness, and the relationship between pulse wave velocity (PWV) and blood pressure (BP) may be different than in other hypertensives. Previous studies showed that when BP decrease is accompanied by PWV decrease the survival is improved. The aim of this study is to examine the...
Preprint
Full-text available
This is a comment on Salvi et al. Hypertension 2019;74:117-129.
Article
Slow breathing is a relaxation exercise with class B, IIa recommendation by the AHA for lowering blood pressure (BP). Biofeedback on the effect of the exercise may improve patient adherence and enhance the BP lowering effect. Conversely, standard BP measurements with occlusion cuffs interfere with relaxation. Hence, the pulse transit time (PTT) is...
Article
Clustering of arterial blood pressure (BP) waveform parameters could summarize complex information into distinct elements, which could be used to investigate cumulative (nonredundant) associations. We investigated this hypothesis in a large, adult population-based study (ViDA trial [Vitamin D Assessment] trial). To interpret the clusters and evalua...
Article
Background: Arterial reservoir-wave analysis (RWA) - a new model of arterial hemodynamics - separates arterial wave into reservoir pressure (RP) and excess pressure (XSP). The XSP integral (XSPI) has been associated with increased risk of clinical outcomes. The objectives of the present study were to examine the determinants of XSPI in a mixed coh...
Preprint
Full-text available
This is a preprint of a comment on an article of P. Salvi et al . published in JAHA: DOI: 10.1161/JAHA.118.011440
Article
Background: Pulsatile hemodynamics predict major cardiovascular events. We aimed to provide comprehensive population-based reference values and to compare different measures of pulsatile hemodynamics to define early vascular aging (EVA) as well as healthy vascular aging (HVA). Methods: In 2721 participants from the population-based Heinz Nixdorf...
Article
Full-text available
Background―Reservoir-wave approach (RWA) is an alternative model of arterial hemodynamics based on the assumption that measured arterial pressure is composed of volume-related (reservoir pressure) and wave-related components (excess pressure). However, the clinical utility of RWA remains debatable. Methods and Results― In a single-center cohort of...
Article
Rationale Patients with end-stage renal disease are characterized by increased cardiovascular and all-cause mortality because of advanced remodeling of the macrovascular and microvascular beds. Objective The aim of this study was to determine whether retinal microvascular function can predict all-cause and cardiovascular mortality in patients with...
Article
Mortality in hemodialysis patients still remains unacceptably high. Enhanced arterial stiffness is a known cardiovascular risk factor, and pulse wave velocity (PWV) has proven to be a valid parameter to quantify risk. Recent studies showed controversial results regarding the prognostic significance of PWV for mortality in hemodialysis patients, whi...
Chapter
The blood pressure category of prehypertension is established by office blood pressure measurement. We investigated the role of 24 h ambulatory blood pressure measurement in subdividing office-based blood pressure categories, establishing the diagnosis of true prehypertension, masked and white-coat hypertension. Furthermore, values of 24 h ambulato...
Article
Full-text available
Background: Association of Ambulatory Blood Pressure Monitoring (ABPM) with mortality depends on cardiac function in hemodialysis patients. Evidence for the predictive power of central Systolic Pressure (cSBP) is inconclusive. Thus, this study aimed to investigate the additional information of ambulatory cSBP in risk prediction in a cohort of hemod...
Article
Full-text available
Background: Conventional brachial cuff BP is known to vary according to age and gender, but the influence of these factors on 24-hour ambulatory central BP is unknown. We sought to determine this in a large healthy population from 11 centers in Europe and Asia. Methods: 24-hour ambulatory BP using a validated oscillometric device (Mobilograph, I.E....
Article
Background: Evidence on the utility of ambulatory BP monitoring for risk prediction has been scarce and inconclusive in patients on hemodialysis. In addition, in cardiac diseases such as heart failure and atrial fibrillation (common among patients on hemodialysis), studies have found that parameters such as systolic BP (SBP) and pulse pressure (PP...
Article
Background: There is increasing evidence that the method of calibration directly influences the association between brachial systolic blood pressure (bSBP) and estimated aortic systolic blood pressure (aSBP) and subsequently affects prognostic and diagnostic differentiation power of the latter. Objective: The aim of this study was to investigate...
Article
We investigated the relationship between left ventricular mass, and brachial office as well as brachial and central ambulatory systolic blood pressure in 7 European centres. Central systolic pressure was measured with a validated oscillometric device, using a transfer function, and mean/diastolic pressure calibration. M-mode images were obtained by...
Article
Background: Pulsatile hemodynamics are associated with left ventricular filling pressures and diastolic dysfunction. We investigated their relationship with maximum workload and peak oxygen uptake (peak VO2) in patients with exertional dyspnea and preserved left ventricular ejection fraction (LVEF). Methods: Radial waveforms from tonometry were...