Determinants of pressure wave reflection: characterization by the transit time-independent reflected wave amplitude

The effects of pressure wave reflection have been incompletely described by the central augmentation index (cAI) and augmented pressure (Pa). We therefore investigated the determinants of amplitude of the reflected wave (Pb), which is independent of the reflected wave transit time (RWTT) and has been shown to predict cardiovascular mortality in the general population. A total of 180 (117 men, mean age 68 years old) patients were recruited. Carotid pressure waveforms derived by tonometry at baseline and 3 min after administration of sublingual nitroglycerin (NTG) were calibrated and then decomposed into the forward and backward waves to yield Pb. The ratio of pre-ejection period/ejection time (PEP/ET) was measured. By stepwise multivariate analysis, independent determinants of Pb included brachial mean blood pressure (β=0.56, P<0.001), heart rate (β=-0.29, P<0.001), age (β=0.20, P<0.001), PEP/ET (β=-0.16, P=0.004) and height (β=-0.13, P=0.018). RWTT, body mass index and sex were significant independent determinants of Pa and cAI but did not contribute to Pb. Change of Pb but not Pa or cAI significantly predicted the changes of carotid systolic (r=0.550, P<0.001) and pulse pressure (r=0.618, P<0.001) after NTG. In conclusion, determinants of Pb differ from those of cAI and Pa. Pb is independent of sex and RWTT.