Background: The measurement of central blood pressure (BPc) has become a matter of importance. Several therapeutic trials have noted a different protective effect against cardiovascular complications with different antihypertensive strategies, but an identical decrease in brachial BP (BPb). A possible explanation lies in the different effects of the treatments on BPc. We propose a new noninvasive method for the automatic measurement of BPc based on the QKD interval, an arterial stiffness marker.
Materials and methods: This study was carried out on patients referred for cardiac catheterization. We simultaneously measured the central SBP (SBPc) invasively with a pigtail probe, and the BPb by a cuff coupled with recording of the QKD interval. Two cohorts were studied, one to define an algorithm of SBPc estimation and one to validate this algorithm.
Results: The first cohort included 65 patients. We performed 136 simultaneous measurements. In the multivariate analysis, four variables were significantly correlated with SBPc: mean BPb (mBPb), QKD, height and heart rate (HR) with the following regression equation: SBP = 105 + 1.29 × mBPb - 0.39 × HR - 0.30 × height - 0.11 × QKD. This equation estimated 81% of the variance of the invasive SBPc ± 13 mmHg. This algorithm was then tested in another cohort of 80 patients. Difference between measured and estimated SBPc was 2 ± 14 mmHg.
Conclusion: This study showed that it is possible to estimate SBPc by simultaneous measurement of QKD and BPb. If further studies confirm these results, a noninvasive ambulatory method of monitoring of SBPc could be employed in clinical practice.