Estimation of central aortic pressure by SphygmoCor® requires intra-arterial peripheral pressures

2003 ◽  
Vol 105 (2) ◽  
pp. 219-225 ◽  
Author(s):  
Geoffrey C. CLOUD ◽  
Chakravarthi RAJKUMAR ◽  
Jaspal KOONER ◽  
Jonathan COOKE ◽  
Christopher J. BULPITT
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Arterial Pressure ◽  
Transfer Functions ◽  
Diastolic Pressure ◽  
Aortic Pressure ◽  
Applanation Tonometry ◽  
Non Invasive ◽  
Central Aortic Pressure ◽  
Diagnostic Cardiac Catheterization

Central arterial pressure, measured close to the heart, may be of more patho-physiological importance than conventional non-invasive cuff blood pressure. The technique of applanation tonometry using SphygmoCor® has been proposed as a non-invasive method of estimating central pressure. This relies on mathematically derived generalized transfer functions, which have been previously validated using invasive peripheral pressure measurements. We compared simultaneous estimates of central aortic pressure using this technique with those measured directly during the routine diagnostic cardiac catheterization of 30 subjects (age range 27–84 years), half of whom were aged 65 years or more. This was done by applanating the left radial artery and recording the non-invasive brachial cuff blood pressure to generate a central aortic pressure estimate, using the SphygmoCor® radial transfer function. The comparative results were analysed using Bland—Altman plots of mean difference. SphygmoCor®, on average, underestimated systolic central arterial pressure by 13.3 mmHg and overestimated diastolic pressure by 11.5 mmHg. The results were similar in patients aged under and above 65 years. Furthermore, non-invasively measured brachial pressures were seen to give an overall closer estimate of the central arterial pressure than the SphygmoCor® system. The transfer function has been validated from invasively measured arterial pressures and the current use by the system of non-invasive measures may explain the discrepancies. However, age, drugs and arterial disease would also be expected to play a role.

Changes in finger-aorta pressure transfer function during and after exercise

2006 ◽  
Vol 101 (4) ◽  
pp. 1207-1214 ◽  
Author(s):  
Wim J. Stok ◽  
Berend E. Westerhof ◽  
John M. Karemaker
Keyword(s):  
Blood Pressure ◽  
Transfer Functions ◽  
Diastolic Pressure ◽  
Systolic Pressure ◽  
Aortic Pressure ◽  
Finger Blood Pressure ◽  
Mean Pressure ◽  
Catheter Tip ◽  
The Individual ◽  
Finger Pressure

Noninvasive finger blood pressure has become a surrogate for central blood pressure under widely varying circumstances. We tested the validity of finger-aorta transfer functions (TF) to reconstruct aortic pressure in seven cardiac patients before, during, and after incremental bicycle exercise. The autoregressive exogenous model method was used for calculating finger-aorta TFs. Finger pressure was measured noninvasively using Finapres and aortic pressure using a catheter-tip manometer. When applying the individual TFs found during rest for reconstruction of aortic pressure during all workloads, systolic pressure was increasingly underestimated, with large variation between subjects: +4.0 to −18.1 mmHg. In most subjects, diastolic pressure was overestimated: −3.9 to +5.5 mmHg. Pulse pressure estimation varied between +4.5 and −21.9 mmHg. In all cases, wave distortion was present. Postexercise, error in reconstructed aortic systolic pressure slowly declined, and diastolic pressure was overestimated. During rest, the TF gain had a minimum between 3.65 and 4.85 Hz (Fmin). During exercise, Fmin shifted to frequencies between 4.95 and 7.15 Hz at the maximum workload, with no change in gain. Postexercise, gain in most subjects shifted to values closer to unity, whereas Fmin did not return to resting values. Within each subject, aorta-Finapres travel time was linearly related to mean pressure. During exercise, Fmin was linearly related to both delay and heart rate. We conclude that, during increasing exercise, rest TFs give an increasingly unreliable reconstruction of aortic pressure, especially at higher heart rates.

Blood Flow Modeling to Improve Cardiovascular Diagnostics: Application of A GTF to Predict Central Aortic Pressure using a 1-D Model

2018 ◽  
Vol 7 (4.26) ◽  
pp. 146
Author(s):  
A. T. Butt ◽  
Y. A. Abakr ◽  
K. B. Mustapha
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Experimental Studies ◽  
Aortic Pressure ◽  
Iliac Arteries ◽  
Central Aortic Pressure ◽  
Blood Flow Modeling ◽  
Feasible Alternative ◽  
Generalized Transfer Function ◽  
Mean Square Errors

This study aims to demonstrate that a comprehensive one-dimensional model of the arterial network can be used in conjunction with the generalized transfer function (GTF) technique to estimate central aortic pressure using pressure waveforms obtained from peripheral sites. The peripheral and central pressure waveforms for a healthy subject are used to estimate transfer functions, which are then used to reconstruct central aortic pressure waveforms for a second model that simulates arterial stiffening. The similarities between the simulated aortic waveform and the waveforms estimated using the transfer function are and   from the brachial, carotid and iliac arteries, respectively. The root-mean-square errors (RMSE) for the reconstructed waveforms from the brachial, carotid and iliac arteries are and  mmHg, respectively. The results from this study illustrate that the proposed method provides a feasible alternative to higher dimensional models as well as experimental studies and can greatly enhance the accuracy of central aortic pressure estimation.     

Physical basis of pressure transfer from periphery to aorta: a model-based study

1998 ◽  
Vol 274 (4) ◽  
pp. H1386-H1392 ◽  
Author(s):  
Nikos Stergiopulos ◽  
Berend E. Westerhof ◽  
Nico Westerhof
Keyword(s):  
Transfer Function ◽  
Delay Time ◽  
Wave Speed ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Considerable Effect ◽  
Distributed Model ◽  
Arterial Tree ◽  
Central Aortic Pressure

We propose a new method to derive aortic pressure from peripheral pressure and velocity by using a time domain approach. Peripheral pressure is separated into its forward and backward components, and these components are then shifted with a delay time, which is the ratio of wave speed and distance, and added again to reconstruct aortic pressure. We tested the method on a distributed model of the human systemic arterial tree. From carotid and brachial artery pressure and velocity, aortic systolic and diastolic pressure could be predicted within 0.3 and 0.1 mmHg and 0.4 and 1.0 mmHg, respectively. The central aortic pressure wave shape was also predicted accurately from carotid and brachial pressure and velocity (root mean square error: 1.07 and 1.56 mmHg, respectively). The pressure transfer function depends on the reflection coefficient at the site of peripheral measurement and the delay time. A 50% decrease in arterial compliance had a considerable effect on reconstructed pressure when the control transfer function was used. A 70% decrease in arm resistance did not affect the reconstructed pressure. The transfer function thus depends on wave speed but has little dependence on vasoactive state. We conclude that central aortic pressure and the transfer function can be derived from peripheral pressure and velocity.

STRUCTURAL AND FUNCTIONAL VASCULAR CHANGES IN HIGH NORMAL ARTERIAL PRESSURE

2020 ◽  
Vol 23 (1) ◽  
pp. 7-11
Author(s):  
P. Nikolov
Keyword(s):  
Arterial Pressure ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Pressure ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Aortic Pressure ◽  
Large Arteries ◽  
Central Aortic Pressure ◽  
Significant Difference

The PURPUSE of the present study is changes in function and structure of large arteries in individuals with High Normal Arterial Pressure (HNAP) to be established. MATERIAL and METHODS: Structural and functional changes in the large arteries were investigated in 80 individuals with HNAP and in 45 with optimal arterial pressure (OAP). In terms of arterial stiffness, pulse wave velocity (PWV), augmentation index (AI), central aortic pressure (CAP), pulse pressure (PP) were followed up in HNAP group. Intima media thickness (IMT), flow-induced vasodilatation (FMD), ankle-brachial index (ABI) were also studied. RESULTS: Significantly increased values of pulse wave velocity, augmentation index, central aortic pressure, pulse pressure are reported in the HNAP group. In terms of IMT and ABI, being in the reference interval, there is no significant difference between HNAP and OAP groups. The calculated cardiovascular risk (CVR) in both groups is low. CONCLUSION: Significantly higher values of pulse wave velocity, augmentation index, central aortic pressure and pulse pressure in the HNAP group are reported.

Wave reflection augments central systolic and pulse pressures during facial cooling

2008 ◽  
Vol 294 (6) ◽  
pp. H2535-H2539 ◽  
Author(s):  
David G. Edwards ◽  
Matthew S. Roy ◽  
Raju Y. Prasad
Keyword(s):  
Cardiovascular Events ◽  
Wave Reflection ◽  
Augmentation Index ◽  
Systolic Pressure ◽  
Aortic Pressure ◽  
Applanation Tonometry ◽  
Pressure Waveform ◽  
Central Aortic Pressure ◽  
Facial Cooling ◽  
Change In Mean

Cardiovascular events are more common in the winter months, possibly because of hemodynamic alterations in response to cold exposure. The purpose of this study was to determine the effect of acute facial cooling on central aortic pressure, arterial stiffness, and wave reflection. Twelve healthy subjects (age 23 ± 3 yr; 6 men, 6 women) underwent supine measurements of carotid-femoral pulse wave velocity (PWV), brachial artery blood pressure, and central aortic pressure (via the synthesis of a central aortic pressure waveform by radial artery applanation tonometry and generalized transfer function) during a control trial (supine rest) and a facial cooling trial (0°C gel pack). Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform. Measurements were made at baseline, 2 min, and 7 min during each trial. Facial cooling increased ( P < 0.05) peripheral and central diastolic and systolic pressures. Central systolic pressure increased more than peripheral systolic pressure (22 ± 3 vs. 15 ± 2 mmHg; P < 0.05), resulting in decreased pulse pressure amplification ratio. Facial cooling resulted in a robust increase in AI and a modest increase in PWV (AI: −1.4 ± 3.8 vs. 21.2 ± 3.0 and 19.9 ± 3.6%; PWV: 5.6 ± 0.2 vs. 6.5 ± 0.3 and 6.2 ± 0.2 m/s; P < 0.05). Change in mean arterial pressure but not PWV predicted the change in AI, suggesting that facial cooling may increase AI independent of aortic PWV. Facial cooling and the resulting peripheral vasoconstriction are associated with an increase in wave reflection and augmentation of central systolic pressure, potentially explaining ischemia and cardiovascular events in the cold.

Determinants of central aortic pressure and pulse pressure amplification changes in patients with aortic aneurysm: the role of aortic diameter and aortic aneurysm location level

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A Gurevich ◽  
I Emelyanov ◽  
N Zherdev ◽  
D Chernova ◽  
A Chernov ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Aortic Aneurysm ◽  
Pulse Pressure ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Aortic Pressure ◽  
Aortic Diameter ◽  
Maximum Diameter ◽  
Central Aortic Pressure ◽  
Abdominal Aortic

Abstract Background The presence of aortic aneurysm can alters pulse wave propagation and reflection, causing changes in central aortic pressure and pulse pressure amplification (PPA) between the aorta and the brachial artery that might be associated with unfavorable hemodynamic effects for the central arteries and the heart. However, the impact of the location of the aneurysm and increase of the aortic diameter on central blood pressure (CBP) is not fully understood. Objective To investigate central aortic pressure and PPA regarding to association with arterial stiffness and aortic diameter in patients with ascending aortic aneurysm (AA), descending thoracic and abdominal aortic aneurysm (TAA and AAA). Methods 122 patients (96 males, 65±11 years) with aortic aneurysm were enrolled before aortic repair. The parameters of the aorta were evaluated by MSCT angiography: 44 patients (30 males, 55±13 years) had AA (the maximum diameter: 59.9±14.2 mm), 13 patients (11 males, 62±11 years) had TAA (the maximum diameter: 62.8±8.0 mm) and 65 patients (54 males, 69±8 years) had AAA (the maximum diameter: 52.3±17.2 mm). Brachial blood pressure (BBP) was measured by OMRON. CBP, augmentation index (AIx), carotid-femoral pulse wave velocity (PWV) were assessed by SphygmoCor. PPA was calculated as a difference between the values of central and brachial pulse pressure (CPP and BPP). Results Patients of the three groups did not differ in BPP (AA: 59.2±17.6; TAA 56.8±12.8; AAA: 59.3±11.4 mm Hg; P=0.5). Intergroup comparison revealed a difference in CPP between the three patients groups: CPP was higher in patients with AA and AAA, lower in patients with TAA (AA: 50.3±16.2; TAA 43.8±10.8; AAA: 50.0±11.2 mm Hg; P=0.05). PPA was lower in patients with AA and AAA than in patients with TAA (9.6±6.7 and 9.3±4.2 vs. 13.0±6.5 mm Hg; P=0.05 and P=0.04, respectively). IAx was higher in patients with AA and AAA than in patients with TAA (25.2±8.1 and 27.6±8.2 vs. 17.2±8.2 mm Hg; P=0.008 and P=0.001, respectively). A decrease of PPA across all patients correlated with an increase of IAx (r = - 0.268; P=0.003). CPP decreased with an increase of the aortic diameter for each level of the aneurysm (AA: r = - 0.460, P=0.016; TAA: r = - 0.833, P=0.003; AAA: r = - 0.275, P=0.05). PWV decreased with the expansion of the maximum aortic diameter at the level of the AA, TAA and AAA: (r = - 0.389, P=0.03; r = - 0.827, P=0.02 and r = - 0.350, P=0.01, respectively). Conclusion In patients with aortic aneurysm measurements of lower central pulse pressure and reduced PWV indicate an association with increased diameter of the aneurysm. An increase in augmentation index, early return of reflected waves, thus smaller PP amplification and higher CPP were identified in patients with ascending and abdominal aortic aneurysm compared by patients with descending thoracic aortic aneurysm. Funding Acknowledgement Type of funding source: None

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