Effect of non-invasive calibration of radial waveforms on error in transfer-function-derived central aortic waveform characteristics

2004 ◽  
Vol 107 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Sarah A. HOPE ◽  
Ian T. MEREDITH ◽  
James D. CAMERON
Keyword(s):  
Transfer Function ◽  
Augmentation Index ◽  
Systolic Pressure ◽  
Function Estimation ◽  
Non Invasive ◽  
Clinical Interest ◽  
Time Parameters ◽  
Generalized Transfer Function ◽  
The Impact ◽  
Significant Underestimation

Transfer function techniques are increasingly used for non-invasive estimation of central aortic waveform characteristics. Non-invasive radial waveforms must be calibrated for this purpose. Most validation studies have used invasive pressures for calibration, with little data on the impact of non-invasive calibration on transfer-function-derived aortic waveform characteristics. In the present study, simultaneous invasive central aortic (Millar Mikro-tip® catheter transducer) and non-invasive radial (Millar® Mikro-tip® tonometer) pressure waveforms and non-invasive brachial pressures (Dinamap®) were measured in 42 subjects. In this cohort, radial waveforms were calibrated to both invasive and non-invasive mean and diastolic pressures. From each of these, central waveforms were reconstructed using a generalized transfer function obtained by us from a previous cohort [Hope, Tay, Meredith and Cameron (2002) Am. J. Physiol. Heart Circ. Physiol. 283, H1150–H1156]. Waveforms were analysed for parameters of potential clinical interest. For calibrated radial and reconstructed central waveforms, different methods of calibration were associated with differences in pressure (P<0.001), but not time parameters or augmentation index. Whereas invasive calibration resulted in little error in transfer function estimation of central systolic pressure (difference −1±8 mmHg; P=not significant), non-invasive calibration resulted in significant underestimation (7±12 mmHg; P<0.001). Errors in estimated aortic parameters differed with non-invasively calibrated untransformed radial and transfer-function-derived aortic waveforms (all P<0.01), with smaller absolute errors with untransformed radial waveforms for most pressure parameters [systolic pressure, 5±16 and 7±12 mmHg; pulse pressure, 0±16 and 4±12 mmHg (radial and derived aortic respectively)]. When only non-invasive pressures are accessible, analysis of untransformed radial waveforms apparently produces smaller errors in the estimation of central aortic systolic pressure, and other waveform parameters, than using a generalized transfer function.

Applanation Tonometry for Assessment of Left Ventricular Systolic Load

2019 ◽  
Vol 12 (2) ◽  
pp. 94-99
Author(s):  
Rene D. Mileva-Popova ◽  
Nina Y. Belova
Keyword(s):  
Arterial Stiffness ◽  
Augmentation Index ◽  
Age Groups ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Applanation Tonometry ◽  
Non Invasive ◽  
Pressure Area ◽  
Older Subjects ◽  
And Gender

Summary Vascular-ventricular coupling is a major determinant of left ventricular load. The aim of our study was to assess non- invasively left ventricular load and its dependency on central hemodynamics. Sixty-five healthy and gender-matched individuals were divided in two groups according to their age: 20y/o and 50y/o. Applanation tonometry was performed using the Sphygmocor device. Central pressures and pulse wave analysis indices were computed. Central systolic (120±3 vs. 98±2 mm Hg) and pulse pressures (43±3 vs. 29±1 mm Hg) as well as the augmentation index (AIx75) (23±3 vs. 6±2%) were significantly higher in the 50y/o group (p<0.01). These parameters are relevant markers of arterial stiffness and evidenced the development of central arterial morphological and functional alterations in the older subjects. The time-tension index (TTI) computed from the systolic pressure area was significantly higher in the 50y/o subjects as compared to the 20y/o group (2378±66 vs. 1954±73 mmHg×s, p<0.01). Moreover, we have shown the presence of significant correlation between TTI and AIx75 (p<0.01) in both age groups. This finding confirmed the contribution of arterial stiffness for the impaired vascular-ventricular coupling. In conclusion, applanation tonometry might be utilized for non-invasive evaluation of the left ventricular load, which is an important parameter of cardiovascular risk.

Comparison of generalized and gender-specific transfer functions for the derivation of aortic waveforms

2002 ◽  
Vol 283 (3) ◽  
pp. H1150-H1156 ◽  
Author(s):  
Sarah A. Hope ◽  
David B. Tay ◽  
Ian T. Meredith ◽  
James D. Cameron
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Diastolic Pressure ◽  
Augmentation Index ◽  
Prognostic Significance ◽  
Systolic Pressure ◽  
Men And Women ◽  
Pressure Time ◽  
And Gender ◽  
Gender Specific

Arterial transfer functions have been promoted for the derivation of central aortic waveform characteristics not usually accessible noninvasively, but possibly of prognostic significance. The utility of generalized rather than gender-specific transfer functions has not been assessed. Invasive central aortic and noninvasive radial (Millar Mikro-tip tonometer) blood pressure waveforms were recorded simultaneously in 78 subjects (61 male and 17 female). Average transfer functions were obtained for the whole group and for each gender by two methods. Reverse transformation was performed with the use of each transfer function. Measured aortic waveform parameters were compared with those derived using average, gender-appropriate, and gender-inappropriate transfer functions. Differences in central waveform characteristics were demonstrated between men and women. Derived waveform parameters were significantly different from measured values [e.g., subendocardial viability index and augmentation index ( P < 0.001)]. A gender-appropriate transfer function significantly improved the derivation of some parameters, including systolic pressure and systolic and diastolic pressure time integrals ( P < 0.05). Generalized arterial transfer functions may not be universally applicable across all waveform parameters of potential interest, and gender-specific transfer functions may be more appropriate.

Markers of arterial stiffness in peripheral arterial disease

VASA ◽  
2015 ◽  
Vol 44 (5) ◽  
pp. 341-348 ◽  
Author(s):  
Marc Husmann ◽  
Vincenzo Jacomella ◽  
Christoph Thalhammer ◽  
Beatrice R. Amann-Vesti
Keyword(s):  
Arterial Stiffness ◽  
Peripheral Arterial Disease ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Arterial Disease ◽  
Care Physician ◽  
Additional Information ◽  
Non Invasive ◽  
Assessment Techniques ◽  
Peripheral Arterial

Abstract. Increased arterial stiffness results from reduced elasticity of the arterial wall and is an independent predictor for cardiovascular risk. The gold standard for assessment of arterial stiffness is the carotid-femoral pulse wave velocity. Other parameters such as central aortic pulse pressure and aortic augmentation index are indirect, surrogate markers of arterial stiffness, but provide additional information on the characteristics of wave reflection. Peripheral arterial disease (PAD) is characterised by its association with systolic hypertension, increased arterial stiffness, disturbed wave reflexion and prognosis depending on ankle-brachial pressure index. This review summarises the physiology of pulse wave propagation and reflection and its changes due to aging and atherosclerosis. We discuss different non-invasive assessment techniques and highlight the importance of the understanding of arterial pulse wave analysis for each vascular specialist and primary care physician alike in the context of PAD.

Relationship between Invasive and Non-Invasive Hemodynamic Measures in Experimental Pulmonary Hypertension

2020 ◽  
Vol 16 (1) ◽  
pp. 47-53
Author(s):  
Vicente Benavides-Córdoba ◽  
Mauricio Palacios Gómez
Keyword(s):  
Heart Rate ◽  
Pulmonary Hypertension ◽  
Ejection Fraction ◽  
Right Ventricle ◽  
Correlation Coefficient ◽  
Pearson Correlation ◽  
Systolic Pressure ◽  
Control Group ◽  
Pearson Correlation Coefficient ◽  
Non Invasive

Introduction: Animal models have been used to understand the pathophysiology of pulmonary hypertension, to describe the mechanisms of action and to evaluate promising active ingredients. The monocrotaline-induced pulmonary hypertension model is the most used animal model. In this model, invasive and non-invasive hemodynamic variables that resemble human measurements have been used. Aim: To define if non-invasive variables can predict hemodynamic measures in the monocrotaline-induced pulmonary hypertension model. Materials and Methods: Twenty 6-week old male Wistar rats weighing between 250-300g from the bioterium of the Universidad del Valle (Cali - Colombia) were used in order to establish that the relationships between invasive and non-invasive variables are sustained in different conditions (healthy, hypertrophy and treated). The animals were organized into three groups, a control group who was given 0.9% saline solution subcutaneously (sc), a group with pulmonary hypertension induced with a single subcutaneous dose of Monocrotaline 30 mg/kg, and a group with pulmonary hypertension with 30 mg/kg of monocrotaline treated with Sildenafil. Right ventricle ejection fraction, heart rate, right ventricle systolic pressure and the extent of hypertrophy were measured. The functional relation between any two variables was evaluated by the Pearson correlation coefficient. Results: It was found that all correlations were statistically significant (p <0.01). The strongest correlation was the inverse one between the RVEF and the Fulton index (r = -0.82). The Fulton index also had a strong correlation with the RVSP (r = 0.79). The Pearson correlation coefficient between the RVEF and the RVSP was -0.81, meaning that the higher the systolic pressure in the right ventricle, the lower the ejection fraction value. Heart rate was significantly correlated to the other three variables studied, although with relatively low correlation. Conclusion: The correlations obtained in this study indicate that the parameters evaluated in the research related to experimental pulmonary hypertension correlate adequately and that the measurements that are currently made are adequate and consistent with each other, that is, they have good predictive capacity.

Effect of alkali therapy with NaHCO3 or THAM on cardiac contractility

1996 ◽  
Vol 270 (5) ◽  
pp. R955-R962
Author(s):  
C. D. Mazer ◽  
B. Naser ◽  
K. S. Kamel
Keyword(s):  
Myocardial Ischemia ◽  
Contractile Function ◽  
Venous Blood ◽  
Systolic Pressure ◽  
Ischemic Myocardium ◽  
Stroke Work ◽  
Length Relationship ◽  
Alkali Therapy ◽  
Myocardial Contractile ◽  
The Impact

We examined the impact of alkali therapy on myocardial contractility in a model of myocardial ischemia in dogs using direct measurements of myocardial contractile function. Myocardial ischemia in the left anterior descending (LAD) artery territory was induced using a perfusion circuit from the internal carotid artery to the LAD artery. Myocardial contractile function was assessed using sonomicrometry for measurement of percent systolic shortening (%SS), preload recruitable stroke work (PRSW) slope, and end-systolic pressure-length relationship (ESPLR) area. Because the blood flow in LAD artery was diminished by approximately 70%, there was a significant decrease in O2 delivery and uptake by the ischemic myocardium. Ischemia led to a significant fall in LAD regional contractile function with %SS decreasing from 15 +/- 2 to 7 +/- 2%, PRSW slope from 82 +/- 10 to 37 +/- 5 mmHg, and ESPLR area from 121 +/- 2 to 48 +/- 14 mmHg.mm (P < 0.05). In six dogs, the intracoronary administration of NaHCO(3) resulted in a significant increase in pH in LAD arterial and venous blood. There was, however, no significant increase in %SS (6 +/- 2), PRSW slope (43 +/- 10 mmHg), or ESPLR area (60 +/- 13 mmHg.mm). Since administration of NaHCO(3) resulted in a significant increase in PCO2 in LAD arterial and venous blood, similar experiments were carried out in five dogs, but with the intracoronary infusion of the amine buffer THAM [tris(hydroxymethyl)aminomethane (Tris) buffer; 2-amino-2-hydroxyl-1,3-propandiol] instead of NaHCO3. Although administration of THAM resulted in a significant increase in pH and a significant decrease in PCO2, in both LAD arterial and venous blood, there was no significant improvement in any of the parameters used to assess myocardial contractile function. In conclusion, administration of alkali (NaHCO3 or THAM) does not enhance the contractile function of the ischemic myocardium.

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.

scholarly journals Flexible Potentiometric Sensor System for Non-Invasive Determination of Antioxidant Activity of Human Skin: Application for Evaluating the Effectiveness of Phytocosmetic Products

Chemosensors ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 76
Author(s):  
Aleksey V. Tarasov ◽  
Ekaterina I. Khamzina ◽  
Maria A. Bukharinova ◽  
Natalia Yu. Stozhko
Keyword(s):  
Antioxidant Activity ◽  
Human Skin ◽  
Skin Diseases ◽  
Silver Chloride ◽  
Potentiometric Sensor ◽  
Sensor System ◽  
Non Invasive ◽  
Pet Film ◽  
The Impact

In contemporary bioanalysis, monitoring the antioxidant activity (AOA) of the human skin is used to assess stresses, nutrition, cosmetics, and certain skin diseases. Non-invasive methods for skin AOA monitoring have certain advantages over invasive methods, namely cost-effectiveness, lower labor intensity, reduced risk of infection, and obtaining results in the real-time mode. This study presents a new flexible potentiometric sensor system (FPSS) for non-invasive determination of the human skin AOA, which is based on flexible film electrodes (FFEs) and membrane containing a mediator ([Fe(CN)6]3–/4–). Low-cost available materials and scalable technologies were used for FFEs manufacturing. The indicator FFE was fabricated based on polyethylene terephthalate (PET) film and carbon veil (CV) by single-sided hot lamination. The reference FFE was fabricated based on PET film and silver paint by using screen printing, which was followed by the electrodeposition of precipitate containing a mixture of silver chloride and silver ferricyanide (SCSF). The three-electrode configuration of the FPSS, including two indicator FFEs (CV/PET) and one reference FFE (SCSF/Ag/PET), has been successfully used for measuring the skin AOA and evaluating the impact of phytocosmetic products. FPSS provides reproducible (RSD ≤ 7%) and accurate (recovery of antioxidants is almost 100%) results, which allows forecasting its broad applicability in human skin AOA monitoring as well as for evaluating the effectiveness of topically and orally applied antioxidants.

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