A short standardized protocol for measuring the QKD interval: comparison with 24 h monitoring and reproducibility

BACKGROUND: Ambulatory measurement for the QKD interval is a new method for evaluation of the rigidity of large arterial trunks. Reliable indices of arterial rigidity can be distilled from the large number of measurements (usually around 100) obtained during 24 h monitoring. OBJECTIVE: To describe a shorter standardized protocol (4 h) including a 15 min effort test on an ergometric bicycle designed to reduce examination time and generate a wider range of heart rates and blood pressures, to test the equivalence of this short protocol with 24 h monitoring and to test its reproducibility. DESIGN: The results of the short protocol were compared with 24 h monitoring results for 15 subjects. The reproducibility of the short protocol for 15 subjects examined twice within 7 days was studied. RESULTS: We found a good correlation between the values obtained with this method and those from 24 h recordings, with comparable reproducibilities in the determination of QKD for systolic blood pressure 100 mmHg and heart rate 60 beats/min. CONCLUSION: A short (4 h) standardized protocol including an exercise test could replace 24 h ambulatory monitoring to assess arterial distensibility through QKD measurement.