Aortic backward waves derived from wave separation analysis, and end-organ changes
Date
2016
Authors
Ballim, Imraan
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Abstract
Aortic backward (reflected) waves are major determinants of cardiovascular events and their impact is independent of brachial blood pressure. Although aortic backward wave pressures (Pb) can be determined using a triangular flow wave form for wave separation analysis, which is a cheaper and time-efficient method, Pb derived from this approach correlates poorly with Pb derived from measured aortic flow waves. However, the comparative ability of these two Pb measurements to predict end-organ changes remains uncertain. Therefore, we aimed to compare Pb obtained using a triangular flow wave method (Pbtri) and Pb obtained using echocardiographic derived aortic flow velocity waves (Pbecho), and their relationships with left ventricular mass indexed to height2.7 (LVMI). In 394 participants from a black African community sample (age>16years), aortic haemodynamics (applanation tonometry, SphygmoCor software), aortic flow velocity and LVMI (echocardiography) were determined. Bland-Altman analysis revealed that Pbtri overestimated the backward wave pressure by an average of 3.65±3.17mmHg. However, the correlation between the two measurements was markedly high (r2=0.82). Independent of confounders, including age, Pbtri was associated with LVMI (partial r=0.14, p=0.02). Importantly, when comparing the association between Pbecho and LVMI (partial r=0.14, p=0.01) no differences were noted (p=0.35, for comparison of partial r values, Z score). The triangular flow wave form employed for wave separation analysis produces Pb values that are as closely associated with LVMI as those derived from echocardiographic aortic flow wave measurements. Thus, risk prediction using simple approaches to aortic wave separation may be employed.
Description
Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand,
Johannesburg, in fulfillment of the requirements for the degree of Master of Science in
Medicine
Johannesburg, 2016