Pulse Wave Analysis (PWA) and Central Pressures

Besides the determination of aortic PWV, VICORDER® also offers the assessment of central aortic pressures by analysis of the brachial pulse pressure wave, oscillatory pressure determination, and application of a global transfer function. Both, the >>brachial and the central aortic pulse wave, are displayed in real time, with systolic, diastolic, and mean pressure documented. Additionally, central aortic pressures including central pulse pressure, augmentation pressure, and augmentation index (AIx) are determined.
This methodology ensures full disclosure of all procedures and safety concerning attained results, in contrast to cryptic, proprietary algorithms that offer little or no transparency to the operator, returning parameters, such as the AIx allowing no verification.
Here you will find the complete list of VICORDER® parameters of arterial stiffness.

Crucial Differences in Quality of AIx

The determination of central aortic pressures by VICORDER® was widely validated, both in invasive as well as non-invasive studies1234. In all of these scientific studies carried out by renowned independent institutions, VICORDER® excelled, in particular in comparative tests. The deviation to invasive central systolic pressure attained by catheter placed in the aorta to non-invasively assessed central pressures by VICORDER® were minimal. Yet patient comfort, ease of test, and operator independence were rated as being optimal.
Thus the quality of VICORDER® derived augmentation pressure and augmentation index (AIx) is associated and backed by its superior accuracy of non-invasive central pressure readings. In contrast, AIx estimations attained by peripheral pulse waves, in particular from fingertip photo pulse plethysmography, must be considered less reliable.

AIx: Sensitive in Young Adults but Less Powerful in Mid Aged and Elderly

The augmentation index (AIx) has proven to be an adequate screening parameter of vascular ageing in younger adults. Depending on arterial pressure wave reflection properties mainly, AIx is sensitive to any changes within the arterial vasculature. Yet its specificity and predictive power in a middle and advanced aged population is less convincing, as AIx rises rapidly in younger ages but levels off after the third decade of life. Therefore its applicability in the clinically more interesting higher decades is limited. Aortic PWV seems to offer a much more relevant model, certainly much more powerful in predicting and differentiating arterial stiffness and associated cardio-vascular disease. AIx exhibits also a much wider variability than PWV. So far no internationally accepted normative AIx data have been published.

Additional Features: Non-invasive Cardiac Output

With a proprietary algorithm VICORDER® estimates stroke volume by analyzing the central pulse wave. This fast and exceptionally comfortable assessment of stroke volume and cardiac output is entirely operator independent offering good reproducibility.

Additional Features: Diastolic Function by SEVR

As a further parameter derived from the central pulse wave, VICORDER® assesses the Subendocardial Viability Ratio (SEVR) as a measure of diastolic function. Arterial stiffness and modified pulse wave reflection lead to both, augmentation of systolic central pressure and lowing of diastolic pressure. Consequently, increased left ventricular load is topped by decreased diastolic pressure, detrimental to diastolic organ perfusion, primarily to the filling of the coronaries. SEVR has proven to be a sensitive parameter even in healthy individuals with sedentary lifestyle.

Literature:

1 G. Pucci, J. Cheriyan, A. Hubsch, S.S. Hickson, T. Watson, G. Schillaci, I.B. Wilkinson, C.M. McEniery. VALIDATION OF VICORDER® & SPHYGMOCOR WITH INVASIVE BLOOD PRESSURE. e168 Journal of Hypertension, e-Supplement A, 2010

2 A. Redheuil, M. Bensalah, N. Kachenoura, E. Bruguiere, A. Azarine, L. Perdrix, E. Bozec, P. Boutouyrie, A. DeCesare, E. Mousseaux. Measuring aortic distensibility with CMR using central pressures estimated in the magnet: comparison with carotid and peripheral pressures. Journal of Cardiovascular Magnetic Resonance
2011

3 G. Pucci, L. Whittaker, S.S. Hickson, J. Cheriyan, G. Schillaci, C.M. McEniery, I.B. Wilkinson. VICORDER® APPARATUS FOR NON-INVASIVE ASSESSMENT OF CENTRAL BLOOD PRESSURE: REPEATABILITY AND COMPARISON WITH THE SPHYGMOCOR DEVICES. Artery 9 Congress, Cambridge, UK, 2009

4 G. Pucci 1,2,3, J. Cheriyan 1,3, A. Hubsch 1, Stacey S. Hickson 1, PR. Gajendragadkar 1, T. Watson 3, M. O’Sullivan 3, J. Woodcock-Smith 1, G. Schillaci 2, Ian B. Wilkinson 1, CM. McEniery 1. Evaluation of the Vicorder, a novel cuff-based device for the noninvasive estimation of central blood pressure. Journal of Hypertension 2012, 30:000–000, online Prepublication