RESUMO
Pulse wave velocity (PWV) has been established as a promising biomarker in cardiovascular diagnostics, providing deep insights into vascular health and cardiovascular risk. Defined as the velocity at which the mechanical wave propagates along the arterial wall, PWV represents a useful surrogate marker for arterial vessel stiffness. PWV has garnered clinical attention, particularly in monitoring patients suffering from vascular diseases such as hypertension and diabetes mellitus. Its utility extends to preventive cardiology, aiding in identifying and stratifying cardiovascular risk. Despite the development of various measurement techniques, direct or indirect tonometry, Doppler ultrasound, oscillometric analysis, and magnetic resonance imaging (MRI), methodological variability and lack of standardization lead to inconsistencies in PWV assessment. In addition, PWV can be estimated through surrogate parameters, such as pulse arrival or pulse transit times, although this heterogeneity limits standardization and, therefore, its clinical use. Furthermore, confounding factors, such as variations in sympathetic tone, strongly influence PWV readings, thereby necessitating careful control during assessments. The bidirectional relationship between heart rate variability (HRV) and PWV underscores the interplay between cardiac autonomic function and vascular health, suggesting that alterations in one could directly influence the other. Future research should prioritize the standardization and increase comparability of PWV measurement techniques and explore the complex physiological variables influencing PWV. Integrating multiple physiological parameters such as PWV and HRV into algorithms based on artificial intelligence holds immense promise for advancing personalized vascular health assessments and cardiovascular care.
RESUMO
Objectives: Nocturnal blood pressure (BP) monitoring is essential for evaluating cardiovascular risk and guiding treatment decisions. However, the standardized narrow-fixed nighttime period between 10 p.m. and 6 a.m. may not accurately reflect individual sleep schedules. This pilot study aimed to investigate the comparability between the standardized nighttime period and actual time in bed (TIB) regarding BP assessment. Further, our goal was to evaluate the clinical relevance of the observed BP differences. Methods: A total of 30 participants underwent 24 h ambulatory blood pressure monitoring (ABPM). Patient-specific TIB was precisely assessed through an accelerometer and a position sensor from the SOMNOtouch NIBP™ (SOMNOmedics GmbH, Randersacker, Germany). We analysed the effect of considering individual TIB as nighttime instead of the conventional narrow-fixed interval on the resulting nocturnal BP levels and dipping patterns. Results: We observed differences in both systolic and diastolic BP between the standardized nighttime period and the TIB. Furthermore, a notable percentage of patients (27%) changed their dipping pattern classification as a function of the nighttime definition adopted. We found strong correlations between the start (r = 0.75, p < 0.01), as well as the duration (r = -0.42, p = 0.02) of TIB and the changes in dipping pattern classification. Conclusions: Definition of nocturnal period based on the individual TIB leads to clinically relevant changes of nocturnal BP and dipping pattern classifications. TIB is easily detected using a body position sensor and accelerometer. This approach may thus improve the accuracy of cardiovascular risk evaluation and enhance treatment strategies.