2.8 INVASIVE STUDY FOR TESTING NON-INVASIVE METHODS OF AORTIC PRESSURE ESTIMATION

Abstract

Purpose: Aortic blood pressure has a superior prognostic value with respect to the brachial pressure [ 1]. Nonetheless, the low efficacy of the most used non-invasive methods (i.e., approaches based on the generalized transfer function (GTF)) may hamper the detection of this superiority in population studies [2]. In this sense, low-order, patient-specific whole-body mathematical models might help to bridge brachial to aortic pressure waveforms. We aimed to compare (i) GTF, (ii) a patient-specific 1D-0D mathematical model, and (iii) brachial blood pressure in the estimation of invasive aortic pressure measured through catheter. Method: One-hundred patients referred to diagnostic coronary angiography were included in this study. Brachial pressure was measured with a validated automatic oscillometric device simultaneously to invasive aortic pressure, which was measured with a calibrated fluid-filled catheter. End-systolic and end-diastolic left ventricular volumes, carotid-femoral pulse wave velocity and tonometric radial waveform were measured immediately prior to the invasive procedure and were used to set GTF and the mathematical model. Results: Oscillometric brachial pressure overestimated both systolic (2.4 ± 12.6 mmHg, R2 = 0.71) and diastolic (3.7 ± 9.8 mmHg, R2 = 0.48) aortic pressure. GTF method underestimated systolic (9.4 ± 11 mmHg, R2 = 0.71) and overestimated diastolic (4.5 ± 10.2 mmHg, R2 = 0.4) aortic pressure. Mathematical model underestimated both systolic (4 ± 16.5 mmHg, R2 = 0.47) and diastolic (3.9 ± 10.4 mmHg, R2 = 0.62) aortic pressure. Brachial pressure and GTF methods presented trends toward systolic and diastolic pressure overestimation for higher aortic pressure, while mathematical modeling not. Conclusions: Systolic and diastolic oscillometric brachial pressures give a better predictor of aortic pressure extremes with respect to both GTF- and mathematical model-based methods.