Non-Invasive Methods and Techniques for Central Blood Pressure Estimation: Procedures, Validation, Reproducibility and Limitations

Abstract

Hypertension is a major risk factor for a wide range of cardiovascular diseases and is typically identified by measuring blood pressure (BP) at the brachial artery. Although such a measurement may accurately determine diastolic BP, it does not accurately reflect systolic BP. This is mainly attributed to the fact that blood pressure waveform is distorted as it travels outward from the heart due to the presence of wave reflections from the peripheral arteries. Due to this distortion, blood pressure measured at the brachial artery provides an inaccurate measure of central aortic systolic pressure. However, central systolic BP is an important factor determining cardiac function and work, while central diastolic BP may determine coronary flow. Consequently central (aortic and carotid) pressures are pathophysiologically more relevant than peripheral pressures and thus their non-invasive accurate estimation is challenging and clinically necessary. The purpose of this review is to present methods and techniques that are used for the estimation of central blood pressures and to describe and discuss issues regarding methodological procedures, reproducibility, validity and limitations.

The second systolic radial blood pressure peak predicts cardiovascular risk only in subjects below 50 years of age

“…1 The most commonly applied method for recording the peripheral pressure wave is that of applanation tonometry. 3 This is a relatively simple and reproducible method that records directly the pressure signal by means of pressure-voltage association. Echo-tracking can be also used for the recording of brachial diameter variation with time.…”

“…Echo-tracking can be also used for the recording of brachial diameter variation with time. 3 This technique is more time consuming and requires higher operator skills; it classically applied at the level of carotid artery. 3 The common drawback of both methods is the need of pressure calibration to transform the voltage or diameter waves in pressure waveforms.…”

“…3 This technique is more time consuming and requires higher operator skills; it classically applied at the level of carotid artery. 3 The common drawback of both methods is the need of pressure calibration to transform the voltage or diameter waves in pressure waveforms. 1,3 Moreover, when the radial signal is calibrated by the brachial pressure an additional error is introduced 2,3 due to the presence of PP amplification between the radial and the brachial artery, leading to underestimation of peak SBP as well of SBP2.…”

“…3 The common drawback of both methods is the need of pressure calibration to transform the voltage or diameter waves in pressure waveforms. 1,3 Moreover, when the radial signal is calibrated by the brachial pressure an additional error is introduced 2,3 due to the presence of PP amplification between the radial and the brachial artery, leading to underestimation of peak SBP as well of SBP2. Recently a new oscillometric method was applied to assess the pressure waveform at the brachial artery.…”

“…This hypothesis launched a new era in hypertension research that aims at the noninvasive assessment of central hemodynamics, although it is clear that this approach has methodological limitations. 3 An alternative approach would be to analyze the peripheral pressure waveform, beyond peak SBP and end diastolic blood pressure, to obtain more information related to the central hemodynamics.…”