One hundred years of auscultatory blood pressure

Perhaps not all hypertensiologists are aware that the last part of the nineteenth century was a period of intensive research with respect to the goal of devising methods for the measurement of blood pressure accurately and non-invasively. Not only investigators from different medical branches, but also biologists and physicists from different countries were involved in this effort. Their publications make fascinating reading not only regarding the deep understanding that scientists already had of the physiology of the circulation, as well as the ingenuity of the often complicated machines designed for the measurement of blood pressure, but also for their candor in recognizing failures, the fairness by which they acknowledged other contributions and the openness by which they shared their results, thoughts and hopes with colleagues [1]. Such efforts had their climax in two discoveries that gave medicine a new quantitative dimension and allowed some of the most important cardiovascular research developments of the twentieth century to take place: (i) the description of the Riva-Rocci sphygmomanometer in 1896–97 [2,3] and (ii) the discovery of the Korotkoff sounds in 1905 [4]. The Journal of Hypertension honoured the centenary of the publication on the Riva-Rocci sphygmomanometer some 9 years ago [5] and is now delighted to honour the centenary of the first report on the Korotkoff sounds. The paper by E. Shlyakhto and A. Conrady published in this issue of the journal [6] describes in detail how, in his short and difficult life, Nikolay S. Korotkoff became aware of the arterial sounds that are known by his name, identified their origin and appreciated their potential relationship with blood pressure values. Suffice to say, it is important to remember that the significance of his observations was, and still is, enormous for two major reasons. First, it allowed a more precise assessment of systolic blood pressure and, indeed, in the original publication, it is clearly indicated that systolic blood pressure, as measured by the appearance of the first sound, is several millimeters of mercury higher than the value determined by the perception of the radial pulse suggested by Riva-Rocci. Second, it allowed the measurement of diastolic blood pressure to be added to that of systolic blood pressure, which was not possible using the Riva-Rocci approach. It is somewhat unfortunate that the widespread use of Korotkoff sounds was apparently delayed for several years [7]. Ten years after Korotkoff's publication, Janeway, in one of the first important clinical reports on hypertension (defined solely in terms of systolic blood pressure), acknowledged that ‘the diastolic blood pressure is unquestionably of great importance and in the determination of abnormally high or low blood pressure should have equal consideration, but it is as yet so little used that a consideration of it would go beyond scope of the present paper’ [8]. As a tribute to Korotkoff, the first 2005 issue of the Journal of Hypertension is dedicated to his memory. A fascimile reproduction of his original paper is published, together with an English translation, and Korotkoff's portrait is included in the brief commemorative article by Professors Shlyakhto and Conrady. However, the greatest tribute that we can give this bright scientist is perhaps to remember that, after 100 years and a huge amount of technological research, the sounds that he discovered during his daily surgical routine remain the most accurate method for measuring blood pressure non-invasively in clinical practice and in population studies. Even after 100 years, the ability to assess systolic and diastolic blood pressure values critically continues to contribute to cardiovascular research and knowledge One of the most relevant aspects of the current approach to cardiovascular risk and disease-related vascular damage is the attention given to pulse pressure and large artery stiffness. This would not have been possible without measurement of diastolic blood pressure, and indeed the nosographic entity now called ‘isolated systolic hypertension’ was first described by Volhard in 1918 after he adopted Korotkoff's method for measuring blood pressure: ‘if diastolic blood pressure is low, this means that the aortic windkessel function is compromised, i.e. there is large vessel sclerosis’ [9]. Someone might comment ironically that the centenary of Korotkoff's discovery comes at a time when the auscultatory method is at risk of being replaced by the mounting use of automatic machines largely based on the oscillatory method. However, these machines, although widely and usefully employed in both home and ambulatory blood pressure recorders, actually measure mean blood pressure, and systolic and diastolic values are computed through specific algorithms that must be validated, initially and periodically, through international protocols by comparison with traditional measurements based on Korotkoff sounds [1]. These therefore remain as the standard reference at present, and probably will continue to be so for many years ahead.