Gefäßsteifigkeitsmessung als Screening-Verfahren zur verbesserten Beurteilung des kardiovaskulären Risikos

Abstract

In 2003 the ESH/ESC recommended the arterial stiffness measurement for arterial hypertension management in their guidelines for the first time. In addition to the conventional blood pressure measurement, the clinicians are advised to measure following parameters: pulse wave velocity (PWV), augmentation pressure (AugP) and central blood pressure (zBD). A change in shape of the blood pressure wave can indicate early atherosclerotic changes of the vascular walls of the elastic arteries. The evaluation of noninvasively recorded pulse wave shapes in real-time with a usable, valid, automated and independent of age operating system is at the moment an unsolved problem. In this scientific work, a new process for arterial stiffness measurement was methodically developed in three main parts: In the first part, the pulse wave recording was realised with a blood pressure cuff at the upper arm. A data capturing system was developed and used for data collection in a heart catheter laboratory. Simultaneous pulse wave recordings noninvasively from the upper arm and invasively from the aorta ascendens were taken from 92 persons undergoing cardiac catheterisation. This data collection of syncing pulse waves established the basis for the second part of the process development. With a systematic selection of 29 datasets a transfer function (UF) was determined. With this UF, new noninvasively recorded pulse waves from the upper arm can be converted into the individual pulse wave shapes of the respective central aortic wave (calculation of zBD). Subsequently, the process was advanced by an implementation of a Windkessel model (WKM) for pulse wave separation (WSA). The model is dimensioned for the individual examined patient with every measurement. The WKM evaluates the characteristic shape of the central pulse wave for every new patient und separates it into a forward and a reflected backward travelling wave from the vascular bed. By means of those pulse wave analysis (PWA) algorithms, the other parameters of arterial stiffness are determined. In the last part, the procedure was examined for reproducibility and repeatability with 20 different test datasets. Besides, the results of the developed algorithms were retrospectively compared with the original results from the heart catheter laboratory. Furthermore, the new measurement technique was compared with gold-standard measurements with SphygmoCor (Co. Atcor Medical). The retrospective Bland-Altman-analysis showed a good agreement of the new arterial stiffness determining algorithms with the standard procedures. The correlation with the invasively measured blood pressure was r = 0.89 (P = 99 %). The mean difference for PWV-determination in comparison with SphygmoCor was 0.09 m/s (SD 1.6 m/s). This work presents the results of the development of a new blood pressure device advanced with a function for arterial stiffness measurement. The developed algorithms proceed in real-time and were implemented in a compact measurement system. After successful market approval, the system will be usable for arterial stiffness screening in clinical practice.