P6.19: Physiological Correlates of Aortic Reservoir and Excess Pressure in Man

• Published in: Artery research Vol. 7; no. 3-4; p. 159
• Main Authors: Schultz, M. G., Davies, J. E., Hardikar, A., Pitt, S., Hughes, A. D., Sharman, J. E.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2013; Springer Nature B.V; BMC
• Subjects: Conference Abstract; Flow velocity; Physiology
• ISSN: 1872-9312; 1876-4401; 1876-4401
• DOI: 10.1016/j.artres.2013.10.200

Background Central (aortic) blood pressure (BP) indices independently predict cardiovascular events and all-cause mortality, but the physiological mechanisms underlying aortic BP waveform morphology are subject to debate. The ‘aortic reservoir’ and ‘excess pressure’ are proposed as determinants of aortic BP, but this relationship has only been assessed using a mathematically-derived aortic reservoir-excess pressure model (AR derived and XP derived ). This study aimed to directly measure the aortic reservoir (AR direct ; by cyclic change in aortic volume) and determine the relationship with AR derived and aortic BP. Methods Ascending aortic BP and Doppler flow velocity were recorded via intra-arterial wire in 10 males (aged 62±12 years) during coronary artery bypass graft surgery. Simultaneous ascending aortic transesophageal echocardiography was used to measure AR direct . Published mathematical formulae were used to determine AR derived and XP derived . A direct excess pressure (XP direct ) was calculated by subtracting AR direct from aortic BP. Results When normalised to the same scale (Figure A), AR direct (solid line) was strongly and linearly related to AR derived (broken line) during systole (r=0.980, P<0.001, Figure B, point 1–2) and diastole (r=0.987, P<0.001 Figure B, point 2–3). The cyclic relationship between aortic BP and AR direct was qualitatively and quantitatively (P>0.05) similar to the cyclic relationship between aortic BP and AR derived . Furthermore, XP direct was linearly related to XP derived during systole (r=0.909, P<0.001) and diastole (r=0.663, P<0.001). Conclusion Aortic reservoir and excess pressures are physiological phenomena highly related to mathematically-derived aortic reservoir, excess pressure and aortic BP.