DAY/NIGHT DIFFERENCES IN PARAMETERS OF VENTRICULAR EJECTION FROM OSCILLOMETRIC PULSE WAVE MEASUREMENTS

Abstract

Objective: The ejection duration (ED) is an important indicator of both ventricular function and ventriculo-arterial coupling. Wave intensity analysis (WIA) is a promising technique for assessment of the cardiovascular performance based on pulse wave analysis (PWA). Previous studies have indicated that 24-hour PWA measurements with oscillometric devices may provide important additional information on cardiac function compared to single measurements. Thus, the aim of this study was to perform PWA with additional ED calculation and WIA on 24-hour pressure wave measurements and to analyse differences between day and night. Design and method: 24 h PWA measurements were carried out on 84 patients (age: 62 years (10 SD), 25 female/59 male) with the Mobil-O-Graph device (IEM, Germany). Wave intensity was determined using central pressure derived from brachial recordings and a model-based blood flow. The SD-ratio (SDR) was defined as the ratio of the first and second peak of the forward wave intensity. Daytime (9–21 h) and nighttime (0–6 h) means were calculated and compared. Results: Peripheral and central systolic blood pressure dropped at night from 124 to 114 mmHg and from 114 to 105 mmHg, respectively (p < 0.001), and the heart rate was significantly higher during nighttime (70 vs 63 bpm, p < 0.001). The ejection duration was shorter during nighttime (310 vs 343 ms, p < 0.001) and the SDR was lower during nighttime (2.54 vs 3.21, p < 0.001), see Table. The differences between day and night averages of heart rate were inversely correlated to those in ejection duration (r = −0.49, p < 0.001) and not correlated with those in SDR (r = 0.07, p = 0.55). Conclusions: Determination of ejection duration and wave intensity analysis from oscillometric 24-hour PWA measurements is feasible. We observed diurnal trends, particularly there were significant differences in ejection duration and SDR between day- and nighttime. The prolongation of the ejection duration during nighttime was partly related to a decreased heart rate, while no relation between the changes in heart rate and SDR could be found. Further studies should investigate how the day/night changes differ between particular patient groups.