Arterial wave reflections: Looking beyond the first harmonic and pressure inflection points to assess late-systolic ventricular loading

Timothy Phan, John Li, Zoubair Ahmed, Ejaz Shah, Vandan Panchal, Julio Chirinos
2015 Artery Research  
Late-systolic ventricular loading is associated with impaired relaxation and adverse remodeling. Standard indices of relative wave reflections such as augmentation index (AIx) and reflection magnitude (RM) from wave separation analysis blend different times within the cardiac cycle and are unspecific to their loading in late-systole. We introduce an index of late-systolic load (QfQ rep ), derived from wave transmission theory that integrates increased and earlier reflections specifically during
more » ... specifically during late-systole while inherently normalized to the associated flow wave. Methods: Central pressure and flow were measured in 226 subjects using carotid tonometry and phase-contrast MRI, respectively. AIx and RM were determined using standard methods. Reflected wave transit time (RWTT TUBE ) was determined using tube-load modeling. Results: Decreased RWTT TUBE (standardized bZ-0.525; P<0.001) and increased RM (bZ0.629; P<0.001) were significantly associated with QfQ rep (R 2 Z0.791). Conclusion: QfQ rep is strongly predicted by wave reflection timing and two standard wave reflection indices. RM is defined by the amplitude of the composite backward wave normalized by that of the composite forward wave, both of which occur at different times. AIx, also blending two different times, combines an early-systolic inflection point with a generally late-systolic pressure peak. The advantage of QfQ rep is that it focuses on the reduced-ejection period to integrate effects of increased and earlier effects of reflections in late-systole. QfQ rep can be obtained readily from standard wave separation analysis.
doi:10.1016/j.artres.2015.10.325 fatcat:g2ygxzwpureixk6pqxmxn5sbgi