Parametric model derivation of transfer function for noninvasive estimation of aortic pressure by radial tonometry

Fetics, Barry; Nevo, Erez; Chen, Chen‐Huan; Kass, David A.

doi:10.1109/10.764946

Cited by 189 publications

(147 citation statements)

References 17 publications

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“…Several invasive studies tested SC's GTF for cSBP estimation from radial pressure waveforms. [5][6][7][8][9] However, they calibrated radial waveforms by 'invasive' central DBP and MAP and not oscillometric arm pressures, which is how SC measurements are done in practice. Later, other invasive studies consistently showed that cSBP estimated by a GTF with 'non-invasively' calibrated radial waveforms significantly underestimated invasively measured cSBP [10][11][12] with the mean difference being 11-13 mm Hg in two studies, 10,27 7-8 mm Hg in three 11,28,29 and 1.5-4.2 mm Hg in two reports.…”

Section: Discussionmentioning

confidence: 99%

“…The GTF has been derived and tested in several invasive studies using 'invasive' calibration of radial waveform. [5][6][7][8][9] However, there is still controversy over accuracy of the typical outpatient SC measurements using 'noninvasive' calibration with brachial pressures, and in different patient populations. 4,[10][11][12][13][14] Recently, two other non-invasive devices that do not use a transfer function have been introduced for cSBP and wave reflection measurement, the Omron HEM-9000 (OM) (Omron Healthcare, Kyoto, Japan) and Arteriograph (AG) (TensioMed, Budapest, Hungary).…”

Section: Introductionmentioning

confidence: 99%

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Calibration mode influences central blood pressure differences between SphygmoCor and two newer devices, the Arteriograph and Omron HEM-9000

et al. 2011

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The objective of this study was to compare central systolic blood pressure (cSBP) and augmentation index (AIx) from two recently introduced devices, Omron HEM-9000 (OM) and Arteriograph (AG), not using a transfer function with those of the widely used SphygmoCor (SC) calibrated on brachial blood pressure like OM. Random-order manufacturer-recommended measurements using SC and OM by radial tonometry and AG were taken on the left arm in 35 men (54±10 years) after 5 min supine rest. Results are means (95% confidence interval) of differences using paired t-tests. cSBP by OM was 4.1 (1.0-7.1) mm Hg higher than by AG. Both OM and AG estimated the mean cSBP to be significantly higher than did SC (114.8 mm Hg) by 12.5 (10.3-14.7) and 8.6 (4.9-12.3) mm Hg, respectively, although closely correlating with SC (r¼0.9). Calibrating SC with diastolic blood pressure (DBP) and more accurate mean arterial pressure (as DBP+0.4ÂPP) resulted in significantly higher cSBP statistically not different from AG's cSBP: 0.9 (À1.1 to +2.9)mm Hg, and closer to OM's: 5.1 (3.4-6.8)mm Hg. Radial AIx from SC and OM disagreed by 3 (0.7-5.4)%, and correlated (r¼0.8) with AG's brachial AIx. AG's aortic AIx was 7.9 (5.7-10.2)% higher than SC's, but closely correlated (r¼0.9). Clinically significant, higher cSBP measured by AG, OM and more accurately calibrated SC adds to previous data suggesting that SC measurements by classic calibration underestimate cSBP. Invasive studies involving all three devices would be more illuminating. INTRODUCTIONCentral blood pressure (cSBP) and indices of wave reflections have become relevant to cardiovascular risk stratification and hypertension management. The primary organs targeted by hypertensive damage (heart, brain and kidneys) may be exposed more closely to aortic blood pressure (BP) and pulsations rather than that estimated by traditionally measured brachial pressures. 1 Moreover, antihypertensive medications may affect central and peripheral pressures differently 2 which could influence drug efficacy and risk reduction. 3 Our previous data from the CAFE study suggested that one drug class and combination produced greater central but not peripheral BP change based on SphygmoCor (SC). 2 There are still few large cohort studies comparing the prospective value of central versus peripheral (brachial) pressures, but a number of small to medium size studies have demonstrated the value of invasively measured central systolic and pulsating pressures prospectively. 4 Large trials demand quick non-invasive measurement of central pressures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calibration mode influences central blood pressure differences between SphygmoCor and two newer devices, the Arteriograph and Omron HEM-9000

et al. 2011

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“…The authors confirm prior observations that indicate the use of a general transfer function can show a considerable amount of bias and variation that limits the utility of this approach in accurately predicting the central augmentation index. 10,11 Further support for this contention is provided by a recent study where simultaneous recordings of invasive central aortic and noninvasive radial blood pressure waveforms were made in 78 subjects. 12 Values for the augmentation index, derived using transfer functions applied to the radial waveforms, were significantly different from directly measured values, and no correlation was evident between the 2 estimates.…”

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confidence: 99%

Editorial Commentary

McVeigh¹

2003

Hypertension

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R isk factors for cardiovascular disease mediate their effects by altering the structure, properties, and function of wall and endothelial components of arterial blood vessels. 1 The ability to detect and monitor change in the physical properties of arteries, representative of the cumulative and integrated influence of hemodynamic, metabolic, and inflammatory stimuli in impairing arterial wall integrity, holds potential to intervene at a preclinical stage to prevent or attenuate disease progression. The importance of assessing arterial wall integrity has been highlighted by recent studies demonstrating that a decrease in the pulsatile function of large arteries represents an independent predictor for future cardiovascular events. 2 Information about the interaction between the left ventricle and the physical properties of the arterial circulation can be derived by the descriptive and quantitative analysis of the arterial pressure pulse waveform. 3 Consistent characteristic changes in the pressure pulse waveshape have been described with aging and disease states predisposing to an increase in vascular events. One such age-related change involves a steepening of the pressure decay in diastole, largely determined by impaired buffering function of the proximal aorta. 3,4 Loss of the oscillatory waveform that distorts the proximal portion of diastole from a pure exponential represents a further early and consistent finding with aging and risk factors for cardiovascular disease including hypertension, smoking, and diabetes mellitus. [3][4][5][6][7] This feature arises from reflection of the incident pressure wave generated by the left ventricle from peripheral reflecting sites with a major contribution originating from impedance mismatches in small arteries and arterioles. The progressive appearance of the reflected wave in systole and eventual summation with the forward incident wave results in augmentation of the systolic blood pressure. Given the proximity of the central aorta to the major peripheral reflecting sites in the lower limbs, augmentation of the systolic blood pressure occurs in this vessel before changes are recorded in the upper limb vessels. Recently, techniques based on the determination of a pressure transfer function between the radial artery and the aorta have been employed to provide an estimate of central pressure wave reflection. 8 In this issue of Hypertension, Millasseau et al 9 report on the accuracy of employing a generalized transfer function to the radial artery pressure pulse waveform to provide an estimate of the aortic augmentation index. The accuracy of the approach was assessed against data derived directly from the carotid pressure pulse waveform or after application of a transfer function to the waveform. The authors confirm prior observations that indicate the use of a general transfer function can show a considerable amount of bias and variation that limits the utility of this approach in accurately predicting the central augmentation index. 10,11 Further support for this content...

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“…15,16 The central aortic pressure can also be reconstructed from peripheral arterial pressure measurements by utilizing the transfer function between each pressure waveform. 17,18 In addition, umbilical artery catheterization often performed in critically ill neonates provides continuous monitoring of central aortic pressure (there is a close correlation between descending Ao dp/dtmax and ascending Ao dp/dtmax; descending Ao dp/dtmax = 0.91 × Ao dp/dtmax +79, R=0.93, SEE =61, n=34, unpublished data from our laboratory). Therefore, incorporating the present result of a consistent relationship between the Ao dp/dtmax/ LV dp/dtmax ratio and vascular loading properties into the noninvasively estimated central aortic pressure, together with simultaneously measurement of ascending aortic flow by echocardiography, is a novel method of noninvasive calculation of LV dp/dtmax.…”

Section: Discussionmentioning

confidence: 99%

Relationship of Maximum Rate of Pressure Rise Between Aorta and Left Ventricle in Pediatric Patients Implication for Ventricular-Vascular Interaction With the Potential for Noninvasive Determination of Left Ventricular Contractility

Masutani

Iwamoto

Ishido

et al. 2009

Circ J

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ssessing the ventricular contractile state, coupled with vascular loading conditions, is important for better understanding of the pathophysiology of various cardiovascular diseases. The maximum rate of the ventricular pressure rise (dp/dtmax) provides a simple but reliable measure of ventricular contractility. 1 Despite its apparent preload dependence, 2 this index generally reflects the ventricular contractile state irrespective of ventricular morphology, localized wall motion abnormalities or structural abnormalities, 3 and parallels the change in contractility assessed by load independent indexes in both acute and chronic conditions. 4,5 Thus, ventricular dp/dtmax has been extensively used for the assessment of ventricular contractile function in a variety of experimental 6,7 and clinical 8 settings. However, determination of this index requires invasive measurement of ventricular pressure by intraventricular catheterization, thus limiting its bed-side clinical applicability.Blood flow ejected from the left ventricle (LV) into the arterial system generates aortic pressure depending on the interaction betweenthe ventricular and vascular properties. Increased blood flow induced by increased LV contractility (LV dp/dtmax) produces a rapid rise in aortic pressure, whereas changes in arterial properties under constant blood flow alter the way in which the aortic pressure develops. Therefore, it is highly possible that the maximum rate of aortic pressure rise (Ao dp/dtmax) and LV dp/dtmax could have an intrinsic correlation that depends on the vascular mechanical and loading properties. If the relationship between Ao dp/dtmax and LV dp/dtmax is quantitatively determined, then the LV dp/dtmax can be calculated from Ao dp/dtmax, potentially providing a method of noninvasively estimating LV contractility.The present study was conducted to test 2 hypotheses: (1) that the ratio between Ao dp/dtmax and LV dp/dtmax is consistent among patients despite marked differences in underlying cardiac disease, contractile state and heart rate (HR) when vascular mechanical and loading properties are taken into account, and (2) that based on such a relationship, LV dp/dtmax can be accurately estimated from Ao dp/dtmax. The maximum rate of the ventricular pressure rise (dp/dtmax) provides a reliable measure of ventricular contractility. However, its estimation requires invasive measurement of left ventricular (LV) pressure, limiting its bedside clinical applicability. In the present study, 2 hypotheses were tested: (1) that the ratio of dp/dtmax between the aorta (Ao) and LV is consistent among patients despite marked differences in underlying cardiac disease, contractile state and heart rate when vascular mechanical and loading properties are taken into account, and (2) that using such a relationship, LV dp/dtmax can be estimated from Ao dp/dtmax, potentially providing a method of noninvasive determination of LV contractility. Methods and Results:Data from 30 control children and 45 pediatric patients with various cardiovascular dis...

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Parametric model derivation of transfer function for noninvasive estimation of aortic pressure by radial tonometry

Cited by 189 publications

References 17 publications

Calibration mode influences central blood pressure differences between SphygmoCor and two newer devices, the Arteriograph and Omron HEM-9000

Calibration mode influences central blood pressure differences between SphygmoCor and two newer devices, the Arteriograph and Omron HEM-9000

Editorial Commentary

Relationship of Maximum Rate of Pressure Rise Between Aorta and Left Ventricle in Pediatric Patients Implication for Ventricular-Vascular Interaction With the Potential for Noninvasive Determination of Left Ventricular Contractility

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