High fidelity applanation tonometer

Central (aortic) BP represents the BP acting directly on internal organs like heart and kidney and have been found to independently predict cardiovascular outcome [15 (link)]. A validated system (SphygmoCor XCEL System; AtCor Medical, Sydney, Australia) was used to derive the central systolic BP (cSBP) and central pulse pressure (cPP) [16 (link)]. Brachial artery pressure curves were recorded from the brachial artery, with the patient being in a supine position, using a high-fidelity applanation tonometer (Millar Instruments, Houston, Tex.), directly into the SphygmoCorTM System which then calculated the corresponding central aortic waveform. After previous calibration, corresponding central (aortic) waveforms were automatically calculated from the brachial artery waveform by a validated transfer function. From the derived central waveforms, data for cSBP, cPP, forward and backward wave amplitude were provided.

To derive the central (aortic) arterial waveform, a validated system (SphygmoCorTM System; AtCor Medical, Sydney, Australia) was applied [5 (link), 7 (link), 20 (link)] by recording radial artery waveforms from the radial artery at the wrist, using high-fidelity applanation tonometer (Millar Instruments, Houston, Tex.) [5 (link), 6 (link), 20 (link)]. Corresponding central (aortic) waveforms were then automatically generated from the radial artery waveform by a validated transfer function [5 (link), 7 (link)]. This allows obtainment of the following parameters: central systolic pressure, central pulse pressure, central augmentation pressure, central augmentation index (cAIx), cAIx normalized to a heart rate of 75 beats per minute (cAIx@75), pulse pressure amplification, as well as forward and backward reflected wave amplitude.