Letters to the Editor: Central Versus Peripheral Blood Pressure Measurements

M. Safar
2005 Hypertension  
One of the major difficulties of blood pressure (BP) measurements in clinical and experimental studies 1 is the presence of systolic BP (SBP) and pulse pressure (PP) amplification. 2 Because of the summation of the forward and backward pressure waves along the arterial tree, SBP and PP are significantly higher (Ϸ14 mm Hg in humans) in peripheral than in central arteries, whereas diastolic and mean BP are similar or even somewhat lower (Ϫ1 mm Hg). 2 This finding, widely accepted as a classical
more » ... ed as a classical scientific result, has never been noted in any guideline of the literature on hypertension but has major consequences, which are poorly considered as relevant and are not discussed in the present recommendations. 1 First, brachial (humans) and tail (rodents) BPs are quite indirect measurements to consider whether the goal of BP determinations is to establish a diagnosis and to evaluate end organ damage. 3 In small animals, tail SBP measurements may even be considered very semiquantitative determinations, quite inappropriate compared with central BP measurements. Second, the phenotypic aspects of the BP curve differ markedly in peripheral and central arteries, and also according to age, because they are largely depending on the level of arterial stiffness and the timing of wave reflections for each particular artery. For instance, in the thoracic aorta of men, there are at least two phenotypes of the BP curve: one in younger and the other in older subjects. 2 Third, SBP and PP amplifications are highly influenced by heart rate, with major consequences in animals of small size as rodents. For instance, in rats, PP amplification is present in normotensive rats 4 but absent in hypertensive rats because of the association of reduced arterial length and BPinduced increase of arterial stiffness. In hypertensive rats, SBP and PP amplification may be restored after acute BP reduction by converting enzyme inhibitors and calcium entry blockers but not dihydralazine. 4 In this respect, comparisons between rats and mice, which are characterized by quite different heart rate levels, have not been extensively performed, with potential major differences in the interpretation of BP level, organ damage, genes, and even level of myogenic tone. 5
doi:10.1161/01.hyp.0000163555.40611.4a pmid:15837837 fatcat:wrmjquux6zd3pgjubylndfbyte