Acute effects of ultrafiltration on aortic mechanical properties determined by measurement of pulse wave velocity and pulse propagation time in hemodialysis patients

Abstract Transcathether aortic heart valve replacement (TAVR) is a widespread approach to treating patients with severe aortic stenosis. A TAVR implant is ideally positioned to access numerous clinically relevant signals including arterial blood pressure, pulse wave velocity, electrocardiogram (ECG), patient motion, heart rate, respiration, and blood oxygenation. Unlike medical devices such as pacemakers, TAVR implants are purely mechanical structures with no sensing capabilities. In this work, we address this unmet clinical need by incorporating an Inter-Integrated Circuit (I2C) sensor network within a TAVR stent frame and designing sensor modules that can physically connect to the network at various landing zones. To illustrate this approach, we designed and built a sensor circuit board populated with a commercial inertial measurement unit (IMU) that can detect clinically useful metrics including pulse wave velocity at the aortic root. We use two spatially separated accelerometers to measure pulse wave propagation time with a standard deviation of 140 μs, which translates to an uncertainty of the pulse wave velocity of ±0.2 m/s. The sensor modules connect to a customized stent frame containing the necessary I2C conductors. Our data suggest that a fully instrumented TAVR paradigm is feasible using this frame design and modular sensor approach.

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Comparison of 24-hour and Office Pulse Wave Velocity for Prediction of Mortality in Hemodialysis Patients

American Journal of Nephrology ◽

10.1159/000499532 ◽

2019 ◽

Vol 49 (4) ◽

pp. 317-327 ◽

Cited By ~ 10

Author(s):

Julia Matschkal ◽

Christopher C. Mayer ◽

Pantelis A. Sarafidis ◽

Georg Lorenz ◽

Matthias C. Braunisch ◽

...

Keyword(s):

Regression Analysis ◽

Pulse Wave Velocity ◽

Wave Velocity ◽

Cardiovascular Mortality ◽

Pulse Wave ◽

Cox Regression ◽

Hemodialysis Patients ◽

Cox Regression Analysis ◽

Kaplan Meier ◽

All Cause Mortality

Background: 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, which may be due to methodological issues, such as assessment of PWV in the office setting (Office-PWV). Method: This study cohort contains patients from the “Risk stratification in end-stage renal disease – the ISAR study,” a multicenter prospective longitudinal observatory cohort study. We examined and compared the predictive value of ambulatory 24-hour PWV (24 h-PWV) and Office-PWV on mortality in a total of 344 hemodialysis patients. The endpoints of the study were all-cause and cardiovascular mortality. Survival analysis included Kaplan-Meier estimates and Cox regression analysis. Results: During a follow-up of 36 months, a total of 89 patients died, 35 patients due to cardiovascular cause. Kaplan-Meier estimates for tertiles of 24 h-PWV and Office-PWV were similarly associated with mortality. In univariate Cox regression analysis, 24 h-PWV and Office-PWV were equivalent predictors for all-cause and cardiovascular mortality. After adjustment for common risk factors, only 24 h-PWV remained solely predictive for all-cause mortality (hazard ratio 2.51 [95% CI 1.31–4.81]; p = 0.004). Conclusions: Comparing both measurements, 24 h-PWV is an independent predictor for all-cause-mortality in hemodialysis patients beyond Office-PWV.

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