Objective: Peripheral (e.g. brachial) Pulse Pressure (Ppp) exceeds central pulse pressure (Cpp) corresponding to the first (Cpp1) or second (Cpp2) peaks in the central waveform. This pulse pressure amplification, attributed to propagation of the pulse wave from aorta to periphery and influence of reflection in the periphery, is measured as Ppp/Cpp2 (when Cpp2 > Cpp1). We examined whether the haemodynamic determinant of Ppp relates more closely to Cpp1 rather than Cpp2.

Methods: We examined the theoretical influence of change in morphology of central aortic waveform on peripheral waveform when applying a reverse transfer function to the aortic waveform. Secondly, we examined the relationship between central and peripheral waveforms during modulation of central pressure with nitroglycerine (GTN). Central pressures were obtained during cardiac atheterization with a Millar catheter placed in the proximal aortic root in patients with non-critical coronary artery disease (n = 15) at baseline and after GTN. The digital arterial pulse was acquired simultaneously with a servo-controlled finger cuff.

Results: In theoretical analysis, Ppp was sensitive only to the portion of the waveform up to the time of Cpp1. Similar results were observed with GTN, which had no significant effect on Cpp1 (38.7 ± 2.0 and 37.1 ± 2.5 mmHg at baseline and after GTN respectively, P = 0.36) nor on Ppp (70.2 ± 5.0 and 69.2 ± 4.7 mmHg at baseline and after GTN respectively, P = 0.47) but reduced Cpp2 by 17.0 ± 1.8 mmHg (P < 0.001).

Conclusions: These results suggest that peripheral pulse pressure is determined by the early systolic portion of the central aortic pressure waveform up to the time of Cpp1 and may be independent of Cpp2.