(715.13) Pressure Only Wave Separation Pulsatile Hemodynamics in Adolescents: Accuracy and Associations with Left Ventricular Mass Index

Poster Board Number: E90

Matthew Armstrong (University of Iowa), Julio Chirinos (University of Pennsylvania), Gaston Kapuku (Augusta University), Gary Pierce (University of Iowa)

Introduction: Early-life exposure to cardiovascular disease (CVD) risk factors, such as high blood pressure (BP), is associated with cardiovascular target organ damage in later life. However, not all BP-related risk is explained by higher systolic and diastolic BP alone. In adolescence, aortic wave separation (WS) pulsatile hemodynamic parameters are associated with adverse left ventricular (LV) structure but are limited by the requirement for measured aortic flow. Several methods for estimating aortic flow from pressure waveforms have emerged, but their accuracy and associations with LV structure have never been tested in adolescents. We hypothesized that pressure-only estimated flow waveforms would: 1) accurately approximate measured flow hemodynamic WS parameters and 2) be similarly associated with LV mass as measured flow hemodynamics among healthy adolescents.

Methods. BP waveforms were acquired via carotid tonometry in 58 adolescents (age 16±1.5 years, 59% females). Measured (aortic) flow and LV mass index (LVMI) were measured via 2D echocardiography. Three pressure-only approximations of aortic flow waveforms were synthesized from analysis of the BP waveform, including triangular, excess, and individualized physiologic flow. A 4th aortic flow waveform (average flow) was approximated from the average of all 58 measured flow waveforms. Forward (Pf) and backward (Pb) pressure and reflection magnitude (Rm) were derived from WS analysis.

Results. Compared to measured flow, individualized physiologic and average flow produced the best approximations of Pf (mean difference ± SD, -0.15±2.38 and 1.23±2.84 mmHg respectively), Pb (0.14±0.25 and 0.67±0.10 mmHg), and Rm (0.01±0.02 and -0.01±0.02 mmHg). Pf derived using all flow waveforms, measured, and estimated, was associated with LVMI (R gt;0.44, P lt;0.001 for all), and these associations yielded similar effect estimates in all instances (z-score lt;1.1, P gt;0.28). All associations persisted after adjusting for age, systolic BP, heart rate, and aortic diameter (P lt;0.05 all).

Conclusion. Of the estimated flow waveforms, individualized physiologic flow yielded the best approximation of WS hemodynamic parameters. It may provide important physiological and clinical insight related to cardiovascular target organ damage among adolescents.

MKA is supported by a National Institutes of Health Cardiovascular Interdisciplinary Research Fellowship grant (reference T32DK007690)