Background: Central blood pressure is a determinant of cardiovascular outcome however it can be described by parameters other than systolic and diastolic pressure with central augmentation index (AIx) often utilised. Although generally considered as determined by peripheral pressure wave reflection the not all data are consistent with this interpretation of AIx. We hypothesised that the velocity of the base of the heart during systole may influence central pressure waveform morphology, including the augmentation index.
Methods: We studied the carotid pressure waveform, aortic stiffness and endothelial function in 20 healthy young males (full data available in 19). Arterial stiffness was measured by carotid-femoral pulse wave velocity (cPWV), endothelial function by Peripheral Arterial Tonometry and central BP waveform by carotid applanation tonometry. Basal cardiac motion was assessed with pulsed wave tissue Doppler imaging of the anterior mitral annulus.
Results: Carotid AIx decreased after the administration of GTN by 11.3 ± (sem)4.6% (P = 0.02) however time to the inflection point (Ti) did not change. During systolic contraction at both baseline and after GTN the time to peak annular systolic velocity was directly related to, and always preceded, carotid Ti (R2 = 0.81; p < 0.01). Carotid Ti and AIx were not related to cPWV or endothelial function.
Conclusion: Rather than only being a consequence of arterial properties Ti, and therefore central AIx, may be substantially determined by left ventricular function. These findings question the interpretation of central AIx as a measure of pressure wave reflection and aortic stiffness and therefore impact on its interpretation in diagnosis and treatment of cardiovascular risk.
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© 2011 Published by Elsevier Inc.
