title: Effect of increased preload on the synthesized aortic blood pressure waveform.
abstract: In the present study, we examined the influence of preload augmentation via passive leg elevation (PLE) on synthesized aortic blood pressure, aortic augmentation index (AIx), and aortic capacitance (a reflection of aortic reservoir function). Central and peripheral hemodynamics were measured via tonometry with a generalized transfer function in 14 young, healthy men (age = 24 yr). Aortic blood flow was calculated from the left ventricular outflow tract (LVOT) velocity-time integral (VTI) using standard two-dimensional echocardiographic-Doppler techniques. Measures were made in the supine position at rest (Pre), during PLE, and during recovery (Post). There was a significant increase in LVOT-VTI, synthesized aortic systolic blood pressure (BP) and AIx from Pre to PLE, with values returning to baseline Post (P < 0.05). There was a reduction in aortic capacitance from Pre to PLE, with values returning to baseline Post (P < 0.05). There was no change in heart rate, systemic arterial compliance, aortic elastance, aortic wave travel timing, or vascular resistance (P > 0.05). Change in AIx from Pre to PLE was associated with change in LVOT-VTI (r = 0.66, P < 0.05) and inversely associated with change in aortic capacitance (r = -0.73, P < 0.05). These data suggest that in a setting of isolated augmented preload with minimal changes in other potential confounders, the morphology of the synthesized aortic BP waveform and AIx may be related to changes in aortic reservoir function.
authors.affiliation: Tufts Medical Center, Molecular Cardiology Research Institute and the Dept. of Medicine, Division of Cardiology, 800 Washington St, Boston, MA 02111, USA. KHeffernan@tuftsmedicalcenter.org
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Heffernan
authors.forename: James E
authors.initials: JE
authors.lastname: Sharman
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Yoon
authors.forename: Eui Jin
authors.initials: EJ
authors.lastname: Kim
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Jung
authors.forename: Sae Young
authors.initials: SY
authors.lastname: Jae
mesh_terms: D001011:Aorta / Q000000981:diagnostic imaging / Q000502:physiology*; D001314:Auscultation; D001794:Blood Pressure; D001916:Brachial Artery / Q000502:physiology; D003187:Compliance; D015150:Echocardiography, Doppler; D006339:Heart Rate; D006801:Humans; D008297:Male; D008365:Manometry; D017534:Radial Artery / Q000502:physiology; D019722:Sphygmomanometers; D016683:Supine Position; D013997:Time Factors; D018924:Vascular Capacitance; D014655:Vascular Resistance; D016277:Ventricular Function, Left; D055815:Young Adult