Response to Central Pressure and Pulse Wave Amplification in the Upper Limb
The purpose of our work1 was to highlight the pathophysiology and potential clinical implications of PP amplification. Several controversial issues remain to be resolved.
The difficulty in defining the normal values of PP amplification is attributed to methodologic drawbacks and to the lack of data from invasive studies on its age-dependent variation. The 2 widely applied noninvasive methods have advantages and disadvantages, which are detailed elsewhere.2 Studies comparing invasively acquired values with those assessed by these noninvasive methods are also lacking. Calibration of the acquired signals with inaccurate noninvasively obtained peripheral blood pressure (BP) is a major common drawback for both methods.
The selected evidence provided by O’Rourke and Adji3 is interesting and adds to the debate about which noninvasive method is more accurate, an issue commented on in our article.1 However, these studies3 did not compare the 2 methods directly. Moreover, the studied populations varied in age, sex, BP level, cardiovascular risk factors, disease, treatment, settings for signal acquisition, and method of calibration. These differences may lead to different results not only between methods but even within the same method.
The 2 noninvasive methods do not provide identical results; the differences are potentially exaggerated depending on the aforementioned factors. The REASON (Preterox Regression of Arterial Stiffness in a Controlled Double-Blind) Study,4 which has applied both methods, showed that the two methods provide close results on central systolic BP, before and after treatment, independent of the treatment arm (systolic BP change: 6.5 versus 4.3 and 15.29 versus 14.46 mm Hg; transfer functions versus carotid tonometry). Both noninvasive methods have proved5 that they predict cardiovascular events and target organ damage, at least as good as peripheral BP.
Each of the authors1 has his/her own preference and reservations on the basis of the accuracy and on the clinical applicability of the 2 methods. Οur collective view is that more data from specifically designed studies are needed to draw a definite conclusion about which is the more accurate method.
Avolio AP, Van Bortel LM, Boutouyrie P, Cockcroft JR, McEniery CM, Protogerou AD, Roman MJ, Safar ME, Segers P, Smulyan H. Role of pulse pressure amplification in arterial hypertension: experts’ opinion and review of the data. Hypertension. 2009; 54: 375–383.
O'Rourke MF, Adji A. Central pressure and pulse wave amplification in the upper limb. Hypertension. 2010; 55: e1–e2.
London GM, Asmar RG, O'Rourke MF, Safar ME; for the REASON Project Investigators. Mechanism(s) of selective systolic blood pressure reduction after a low-dose combination of Perindopril/Indapamide in hypertensive subjects: comparison with Atenolol. J Am Coll Cardiol. 2004; 43: 92–99.
Agabiti-Rosei E, Mancia G, O'Rourke MF, Roman MJ, Safar ME, Smulyan HJ, Wang JG, Wilkinson IB, Williams B, Vlachopoulos C. Central blood pressure measurements and antihypertensive measurements: a consensus document. Hypertension. 2007; 50: 154–160.