Pulse wave reflections reflect cardiac afterload and perfusion, which yield valid indicators for ... more Pulse wave reflections reflect cardiac afterload and perfusion, which yield valid indicators for monitoring cardiovascular status. Accurate quantification of pressure wave reflections requires the measurement of aortic flow wave. However, direct flow measurement involves extra equipment and well-trained operator. In this study, the personalized aortic flow waveform was estimated from the individual central aortic pressure waveform (CAPW) based on pressure-flow relations. The separated forward and backward pressure waves were used to calculate wave reflection indices such as reflection index (RI) and reflection magnitude (RM), as well as the central aortic pulse transit time (PTT). The effectiveness and feasibility of the method were validated by a set of clinical data (13 participants) and the Nektar1D Pulse Wave Database (4,374 subjects). The performance of the proposed personalized flow waveform method was compared with the traditional triangular flow waveform method and the recently proposed lognormal flow waveform method by statistical analyses. Results show that the root mean square error calculated by the personalized flow waveform approach is smaller than that of the typical triangular and lognormal flow methods, and the correlation coefficient with the measured flow waveform is higher. The estimated personalized flow waveform based on the characteristics of the CAPW can estimate wave reflection indices more accurately than the other two methods. The proposed personalized flow waveform method can be potentially used as a convenient alternative for the measurement of aortic flow waveform.
Arterial stiffness index beta and cardio-ankle vascular index inherently depend on blood pressure... more Arterial stiffness index beta and cardio-ankle vascular index inherently depend on blood pressure but can be readily corrected.
Background: Central aortic pressure has often been shown to be more closely associated with marke... more Background: Central aortic pressure has often been shown to be more closely associated with markers of vascular function and incidence of cardiovascular events compared to peripheral pressure. However, the potential clinical use of central aortic or peripheral haemodynamic indices as markers of target organ damage (TOD) has not been fully established. Methods: We evaluated associations of TOD with central aortic and peripheral haemodynamic indices (central aortic [cPP] and peripheral pulse pressure [pPP], central aortic augmentation index, and central and peripheral waveform factor) in 770 hospital inpatients (age 60 ± 10 years, 473 males) with primary hypertension. TOD was quantified in terms of arterial stiffness as measured by carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (IMT), and urine albumin-to-creatinine ratio (ACR). Subclinical TOD was defined as carotid IMT >0.9 mm, urine ACR >3.5 mg/mmol in females and >2.5 mg/mmol in males and/or cfPWV >12 m/s. Results: Both cPP and pPP showed significant correlation with cfPWV ( r = 0.41 vs. 0.40; p < 0.01), ACR ( r = 0.24 vs. 0.27; p < 0.01) and carotid IMT ( r = 0.14 vs. 0.15; p < 0.01). Each SD increase in pPP and cPP was associated with increased risk of cfPWV >12 m/s (odds ratio [OR] = 2.7 and 2.9 for pPP and cPP, respectively), ACR >2.5 mg/mmol (OR = 1.2 and 1.4, respectively), and carotid IMT >0.9 mm (OR = 1.46 and 1.53, respectively). Compared to pPP, cPP had higher predictive power for TOD for age ≥ 60 years (OR = 3.07, p < 0.001). Conclu-
Obesity, generally considered undesirable on account of its association with metabolic syndrome a... more Obesity, generally considered undesirable on account of its association with metabolic syndrome and with other risk factors for cardiovascular disease, presents a global health problem. The incidence of obesity in China ranks second in the world, 1 affecting nearly one-third of the population. Obesity remains a major risk factor for development of heart failure. 2 However, paradoxically, overweight and other obese individuals with established disease can often have better long-term outcome for revascularization and other therapies than do their lean counterparts. The obesity paradox has been shown to be present in populations with heart failure, hypertension, and even in the general population. The ARIC study 10 suggested that the 5-year mortality was lower in overweight (HR 0.68-0.79) and obesity (HR 0.50 ~ 0.63) compared to normal weight in heart failure patients. The mechanisms of the obesity paradox may be related to genetics, 11 cardiopulmonary health, beneficial adipose tissue
Automated 'oscillometric' blood pressure (BP) measuring devices (BPMDs) were developed in the 197... more Automated 'oscillometric' blood pressure (BP) measuring devices (BPMDs) were developed in the 1970s to replace manual auscultatory BP measurement by mercury sphygmomanometer. Automated BPMDs that have passed accuracy testing versus a reference auscultatory sphygmomanometer using a scientifically accepted validation protocol are recommended for clinical use globally. Currently, there are many thousands of unique automated BPMDs manufactured by hundreds of companies, with each device using proprietary algorithms to estimate BP and using a method of operation that is largely unchanged since inception. Validated automated BPMDs provide similar BP values to those recorded using manual auscultation albeit with potential sources of error mostly associated with using empirical algorithms to derive BP from waveform pulsations. Much of the work to derive contemporary BP thresholds and treatment targets used to manage cardiovascular disease risk was obtained using automated BPMDs. While there is room for future refinement to improve accuracy for better individual risk stratification, validated BPMDs remain the recommended standard for office and out-of-office BP measurement to be used in hypertension diagnosis and management worldwide.
Patients with implanted pacemakers or implantable cardioverter defibrillators with pacing functio... more Patients with implanted pacemakers or implantable cardioverter defibrillators with pacing function were recruited from the Cardiac Health Institute and Macquarie Heart clinics. Exclusion criteria included unstable angina, previous myocardial infarction within the last 12 months of the study, and uncontrolled congestive heart failure. A total of 52 subjects (age 40-93 years, 11 female) entered the study, and all were included in the analysis. The study protocol was approved by Macquarie University's Human Ethics Committee and written consent to participate in the study was obtained from all subjects.
Aortic pulse wave velocity (PWV), calculated from pulse transit time (PTT) using 2 separate pulse... more Aortic pulse wave velocity (PWV), calculated from pulse transit time (PTT) using 2 separate pulse recordings over a known distance, is a significant biomarker of cardiovascular risk. This study evaluates a novel method of determining PTT from waveform decomposition of central aortic pressure using a single pulse measurement. Aortic pressure was estimated from a transformed radial pulse and decomposed into forward and backward waves using a triangular flow wave. Pulse transit time was determined from cross-correlation of forward and backward waves. Pulse transit time, representing twice the PTT between 2 specific sites, was compared with independent measurements of carotid-femoral PTT in a cohort of 46 subjects (23 females; age 57Ϯ14 years). Linear regression between measured PTT (y; milliseconds) and calculated PTT (x; milliseconds) was yϭ1.05xϪ2.1 (rϭ0.67; PϽ0.001). This model was tested in a separate group of 44 subjects (21 females; age 55Ϯ14 years) by comparing measured carotid-femoral PWV (y; meters per second) and PWV calculated using the estimated value of PTT (eTR/2) and carotid femoral distance (x; meters per second; yϭ1.21xϪ2.5; rϭ0.82; PϽ0.001). Findings indicate that the time lag between the forward and backward waves obtained from the decomposition of aortic pressure wave can be used to determine PWV along the aortic trunk and shows good agreement with carotid-femoral PWV. This technique can be used as a noninvasive and nonintrusive method for measurement of aortic PWV using a single pressure recording.
Central arterial waveforms can be estimated non-invasively from the combination of peripheral blo... more Central arterial waveforms can be estimated non-invasively from the combination of peripheral blood pressure and peripheral pulse waveform by use of a Transfer Function (TF), or directly measured by tonometry of the centrally located arteries such as the carotid artery . TFs allow waveforms from one part of the vascular system to be mathematically transformed into a waveform at another location within the system, most commonly from a peripheral artery with a readily accessible pulse such as the radial artery to a central artery, such as the ascending aorta. From these synthesized central waveforms, central hemodynamic indices such as cSBP and cAIx can then be extracted. Generalized TFs (gTF) are derived from ensemble-averaged Individualized TFs (iTF), and are widely used in adult hemodynamic research and have an emerging
Objectives: Arterial stiffness index β and cardio-ankle vascular index (CAVI) are widely accepted... more Objectives: Arterial stiffness index β and cardio-ankle vascular index (CAVI) are widely accepted to quantify the intrinsic exponent (β0) of the BP-diameter relationship. CAVI and β assume an exponential relationship between pressure (P) and diameter (d). We aim (1) to demonstrate that, under this assumption, β and CAVI as currently implemented are inherently BP-dependent; and (2) to provide corrected, BP-independent forms of CAVI and β. 1) , usually reference pressure (Pref) and reference diameter (dref) are substituted with diastolic BP and diameter to accommodate measurements. Consequently, the resulting exponent is not equal to the pressure-independent β0. CAVI does not only suffer from this "reference pressure" effect, but also from the approximation of 𝑑P 𝑑d . For example, assuming β0=7, an increase of systolic/diastolic BP from 110/70 to 170/120 mmHg increased β by 8.1% and CAVI by 14.3%. We derived corrected forms of β and of CAVI (CAVI0) that indeed did not change with BP and represent the pressure-independent β0. To substantiate the BP effect on CAVI in a typical follow-up study, we realistically simulated patients (n=161) before and following BP-lowering "treatment" (assuming no follow-up change in intrinsic β0 and therefore in actual P-d relationship). Lowering BP from 160±14/111±11 to 120±15/79±11 mmHg (p<0.001) resulted in a significant CAVI decrease (8.1±2.0 to 7.7±2.1, p=0.008); CAVI0 did not change (9.8±2.4 and 9.9±2.6, p=0.499). Conclusions: β and CAVI as currently implemented are inherently BP-dependent, potentially leading to erroneous conclusions in arterial stiffness trials. BPindependent forms are presented to readily overcome this problem.
Elevated central aortic pressure indices (e.g., systolic pressure and pulse pressure) predict car... more Elevated central aortic pressure indices (e.g., systolic pressure and pulse pressure) predict cardiovascular (CV) events and mortality in addition to structural changes (e.g., left ventricular hypertrophy, carotid intima-media thickness and reduced glomerular filtration rate). These elevated risks have been shown in multiple studies to be superior to, and in others, at least as high as that associated with brachial pressures. Threshold values for the diagnosis of elevated central arterial pressures have been defined and can be considered target goals of treatment. Measurements of central arterial pressures can be incorporated into the current approaches to hypertension management utilizing currently available non-invasive devices that measure central pressures during the measurement of brachial BP. The objective of this review is to outline the rationale and evidence supporting incorporation of central aortic pressure monitoring into the care of patients with hypertension.
ObjectivesThe aim of this study was to explore the risk of target organ damage (TOD) in different... more ObjectivesThe aim of this study was to explore the risk of target organ damage (TOD) in different groups based on carotid-femoral pulse wave velocity (cfPWV) and central aortic blood pressure (CBP) in different populations.MethodsThe study cohort was divided into four groups according to the status of cfPWV and CBP [Group (cfPWV/CBP): high cfPWV and high CBP; Group (cfPWV): high cfPWV and normal CBP; Group (CBP): normal cfPWV and high CBP; Group (control): normal cfPWV and normal CBP]. TOD was determined by the assessment of carotid intima-media thickness (CIMT) abnormality, chronic kidney disease (CKD), microalbuminuria, and left ventricular hypertrophy (LVH).ResultsA total of 1,280 patients (mean age 53.14 ± 12.76 years, 64.1% male patients) were recruited in this study. Regarding Group (control) as reference, LVH was significantly higher in Group (cfPWV) and Group (CBP) [OR 2.406, 95% CI (1.301–4.452), P < 0.05; OR 2.007, 95% CI (1.335–3.017), P < 0.05]; microalbuminuria wa...
ObjectiveAim of this study was to evaluate the associations of non-invasive central aortic and pe... more ObjectiveAim of this study was to evaluate the associations of non-invasive central aortic and peripheral (brachial) blood pressure (BP) for Hypertension-mediated organ damage (HMOD) and atherosclerotic cardiovascular disease (ASCVD) risk.MethodsWe evaluated associations of HMOD with 24-h ambulatory blood pressure monitoring (ABPM) of central aortic and peripheral BP indices in patients with primary hypertension and presence of several cardiovascular risk factors. BP measurements were performed by means of a non-invasive automated oscillometric device (Mobil-O-Graph). HMOD was defined as the presence of carotid intima-media thickness (IMT) above normal values and/or carotid plaque, left ventricular hypertrophy (LVH), and/or renal abnormalities as assessed by urine albumin/creatinine ratio above normal values and/or estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2.ResultsIn the study cohort of 273 (age 55.2 ± 13.4 years, 71.8% male) patients with primary hyperten...
The arterial pulse wave is a physiological signal which can reflect the function of the human car... more The arterial pulse wave is a physiological signal which can reflect the function of the human cardiovascular system. Owing to the measurement being convenient and safe, radial pulse waves have been often used in noninvasive monitoring of human health, which can further reflect the health status of the cardiovascular system, including information of the aorta and peripheral arteries. Moreover, radial pulse waves can assist clinical diagnosis in the prevention and treatment of cardiovascular disease. This paper systematically reviews the progress in analysis of pulse wave analysis, including pulse wave acquisition, waveform processing, pattern classification, parameter estimation, and clinical applications. In terms of waveform acquisition, this paper reviews a variety of methods to obtain radial pulse waves, including tonometry, photoplethysmography, ultrasound manometry, and flexible tactile pressure sensors. In the aspect of waveform processing, this paper summarizes the methods of radial pulse waves preprocessing and feature extraction. With the rapid development of machine learning and deep learning algorithms, radial pulse waves can be used to identify the status of human cardiovascular systems and to estimate parameters related to cardiovascular function. This paper also discusses the applications of radial pulse waves in clinical practice, including cardiovascular function evaluation and pulse diagnosis in traditional Chinese medicine. Some open-source databases and analysis software are also listed. The current development trend, challenges, and future directions of analysis of radial pulse waves are also offered. INDEX TERMS Radial artery, pulse wave, waveform processing, feature extraction, pattern classification, parameter estimation.
BACKGROUND Aortic stiffness as measured by carotid–femoral pulse wave velocity (cfPWV) is known t... more BACKGROUND Aortic stiffness as measured by carotid–femoral pulse wave velocity (cfPWV) is known to depend on blood pressure (BP), and this dependency may change with age. Therefore, the hydrostatic BP gradient resulting from a change in body posture may elicit a cfPWV change that is age-dependent. We aimed to analyze the relationship between BP gradient—induced by head-up body tilting—and related changes in cfPWV in individuals of varying age. METHODS cfPWV and other hemodynamic parameters were measured in 30 healthy individuals at a head-up tilt of 0° (supine), 30°, and 60°. At each angle, the PWV gradient and resulting cfPWV were also estimated (predicted) by assuming a global nonlinear, exponential, pressure–diameter relationship characterized by a constant β0, and taking into account that (diastolic) foot-to-foot cfPWV acutely depends on diastolic BP. RESULTS cfPWV significantly increased upon body tilting (8.0 ± 2.0 m/s supine, 9.1 ± 2.6 m/s at 30°, 9.5 ± 3.2 m/s at 60°, P for ...
Arterial stiffness increases through life due to changes in smooth muscle and endothelial functio... more Arterial stiffness increases through life due to changes in smooth muscle and endothelial function, and alteration of the extracellular matrix through elastin degeneration, collagen cross-linking, and calcification. These processes occur with age and are accelerated in certain diseases including hypertension, diabetes mellitus, and end-stage renal failure . Arterial stiffness as a predictor of cardiovascular disease particularly in the elderly [2] has been receiving increasing interest in preventive health care. The association between cardiovascular disease risk factors and measures of arterial stiffness has been demonstrated in large-population studies . Arterial stiffness has been linked to vascular morbidity and mortality in cohorts with hypertension [6,7], end-stage renal disease [8], and type 2 diabetes mellitus . There is increasing recognition that the interrelations between arterial stiffness and cardiovascular events are mediated by microvascular remodelling and obliteration . Human and animal studies have evidenced arteriolar remodelling and capillary rarefaction in early stages of hypertension . The possibility that the microcirculatory impairment may occur early in the onset of increasing arterial stiffness underlines the importance of monitoring microcirculation for more effective preventive and therapeutic measures .
The retina provides a non-invasive window to monitor microvascular circulation. Carotid-femoral P... more The retina provides a non-invasive window to monitor microvascular circulation. Carotid-femoral Pulse Wave Velocity (cfPWV) is an indicator of large artery stiffness and is associated with systemic cardiovascular diseases. This study investigates whether Retinal artery PWV (rPWV) reflects cfPWV changes in an elderly cohort. Methods: A total of 37 elderly participants (28 female, age 79 ± 5 years) were studied. Participants with a history of diabetes, glaucoma, and any neurological or eye-related disorders were excluded. Twenty four subjects were taking antihypertensive medication. A 60-s recording of retinal arterial diameter changes were captured (25 Hz frame rate, Dynamic Vessel Analyzer). Systolic blood pressure, Diastolic Blood Pressure (DBP), cfPWV and Intraocular Pressure (IOP) were measured. A customwritten algorithm was used to extract pulse amplitudes from retinal arterial diameters within one-and three-disc diameters from the optic disc. rPWV was designated as the ratio of the distance between two sites along the artery to the time delay between pulses. Predictors of rPWV were assessed by linear regression and parameter selection techniques. Results: There was a positive correlation between rPWV and cfPWV (Pearson's correlation coefficient 0.82, p < 0.001). In parameter selection models, cfPWV, transmural pressure (DBP-IOP), male sex, and IOP were isolated as predictors of rPWV. This study found a positive correlation between rPWV and cfPWV in an elderly cohort. This indicates that microvessel remodelling that parallels large vessel remodelling is able to be detected using rPWV measurement. Further longitudinal studies are required to elucidate the predictive value of screening rPWV in systemic cardiovascular abnormalities.
n Z 30) was also associated with gothic arch (p Z 0.01), and dilated ascending aorta but with no ... more n Z 30) was also associated with gothic arch (p Z 0.01), and dilated ascending aorta but with no aortic root dilation (p Z 0.02). On multivariate regression analysis, gothic arch was indeed associated with coarctation and stenosis, and also with non-coronary valve fusion pattern (p Z 0.03). Patients with aortic regurgitation tended to have larger aortas (p Z 0.005). The presence of aortic coarctation and stenosis may influence the amount of dilation and the overall arch architecture in BAV patients. Patients with BAV present profoundly different morphological phenotypes depending on the presence/absence of aortic coarctation (Fig. ).
Aortic pulse wave velocity is a worldwide accepted index to evaluate aortic stiffness and can be ... more Aortic pulse wave velocity is a worldwide accepted index to evaluate aortic stiffness and can be assessed noninvasively by several methods. This study sought to determine if commonly used noninvasive devices can all accurately estimate aortic pulse wave velocity. Pulse wave velocity was estimated in 102 patients (aged 65±13 years) undergoing diagnostic coronary angiography with 7 noninvasive devices and compared with invasive aortic pulse wave velocity. Devices evaluating carotid-femoral pulse wave velocity (Complior Analyse, PulsePen ET, PulsePen ETT, and SphygmoCor) showed a strong agreement between each other ( r >0.83) and with invasive aortic pulse wave velocity. The mean difference ±SD with the invasive pulse wave velocity was −0.73±2.83 m/s ( r =0.64) for Complior-Analyse: 0.20±2.54 m/s ( r =0.71) for PulsePen-ETT: −0.04±2.33 m/s ( r =0.78) for PulsePen ET; and −0.61±2.57 m/s ( r =0.70) for SphygmoCor. The finger-toe pulse wave velocity, evaluated by pOpmètre, showed only ...
Pulse wave reflections reflect cardiac afterload and perfusion, which yield valid indicators for ... more Pulse wave reflections reflect cardiac afterload and perfusion, which yield valid indicators for monitoring cardiovascular status. Accurate quantification of pressure wave reflections requires the measurement of aortic flow wave. However, direct flow measurement involves extra equipment and well-trained operator. In this study, the personalized aortic flow waveform was estimated from the individual central aortic pressure waveform (CAPW) based on pressure-flow relations. The separated forward and backward pressure waves were used to calculate wave reflection indices such as reflection index (RI) and reflection magnitude (RM), as well as the central aortic pulse transit time (PTT). The effectiveness and feasibility of the method were validated by a set of clinical data (13 participants) and the Nektar1D Pulse Wave Database (4,374 subjects). The performance of the proposed personalized flow waveform method was compared with the traditional triangular flow waveform method and the recently proposed lognormal flow waveform method by statistical analyses. Results show that the root mean square error calculated by the personalized flow waveform approach is smaller than that of the typical triangular and lognormal flow methods, and the correlation coefficient with the measured flow waveform is higher. The estimated personalized flow waveform based on the characteristics of the CAPW can estimate wave reflection indices more accurately than the other two methods. The proposed personalized flow waveform method can be potentially used as a convenient alternative for the measurement of aortic flow waveform.
Arterial stiffness index beta and cardio-ankle vascular index inherently depend on blood pressure... more Arterial stiffness index beta and cardio-ankle vascular index inherently depend on blood pressure but can be readily corrected.
Background: Central aortic pressure has often been shown to be more closely associated with marke... more Background: Central aortic pressure has often been shown to be more closely associated with markers of vascular function and incidence of cardiovascular events compared to peripheral pressure. However, the potential clinical use of central aortic or peripheral haemodynamic indices as markers of target organ damage (TOD) has not been fully established. Methods: We evaluated associations of TOD with central aortic and peripheral haemodynamic indices (central aortic [cPP] and peripheral pulse pressure [pPP], central aortic augmentation index, and central and peripheral waveform factor) in 770 hospital inpatients (age 60 ± 10 years, 473 males) with primary hypertension. TOD was quantified in terms of arterial stiffness as measured by carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (IMT), and urine albumin-to-creatinine ratio (ACR). Subclinical TOD was defined as carotid IMT >0.9 mm, urine ACR >3.5 mg/mmol in females and >2.5 mg/mmol in males and/or cfPWV >12 m/s. Results: Both cPP and pPP showed significant correlation with cfPWV ( r = 0.41 vs. 0.40; p < 0.01), ACR ( r = 0.24 vs. 0.27; p < 0.01) and carotid IMT ( r = 0.14 vs. 0.15; p < 0.01). Each SD increase in pPP and cPP was associated with increased risk of cfPWV >12 m/s (odds ratio [OR] = 2.7 and 2.9 for pPP and cPP, respectively), ACR >2.5 mg/mmol (OR = 1.2 and 1.4, respectively), and carotid IMT >0.9 mm (OR = 1.46 and 1.53, respectively). Compared to pPP, cPP had higher predictive power for TOD for age ≥ 60 years (OR = 3.07, p < 0.001). Conclu-
Obesity, generally considered undesirable on account of its association with metabolic syndrome a... more Obesity, generally considered undesirable on account of its association with metabolic syndrome and with other risk factors for cardiovascular disease, presents a global health problem. The incidence of obesity in China ranks second in the world, 1 affecting nearly one-third of the population. Obesity remains a major risk factor for development of heart failure. 2 However, paradoxically, overweight and other obese individuals with established disease can often have better long-term outcome for revascularization and other therapies than do their lean counterparts. The obesity paradox has been shown to be present in populations with heart failure, hypertension, and even in the general population. The ARIC study 10 suggested that the 5-year mortality was lower in overweight (HR 0.68-0.79) and obesity (HR 0.50 ~ 0.63) compared to normal weight in heart failure patients. The mechanisms of the obesity paradox may be related to genetics, 11 cardiopulmonary health, beneficial adipose tissue
Automated 'oscillometric' blood pressure (BP) measuring devices (BPMDs) were developed in the 197... more Automated 'oscillometric' blood pressure (BP) measuring devices (BPMDs) were developed in the 1970s to replace manual auscultatory BP measurement by mercury sphygmomanometer. Automated BPMDs that have passed accuracy testing versus a reference auscultatory sphygmomanometer using a scientifically accepted validation protocol are recommended for clinical use globally. Currently, there are many thousands of unique automated BPMDs manufactured by hundreds of companies, with each device using proprietary algorithms to estimate BP and using a method of operation that is largely unchanged since inception. Validated automated BPMDs provide similar BP values to those recorded using manual auscultation albeit with potential sources of error mostly associated with using empirical algorithms to derive BP from waveform pulsations. Much of the work to derive contemporary BP thresholds and treatment targets used to manage cardiovascular disease risk was obtained using automated BPMDs. While there is room for future refinement to improve accuracy for better individual risk stratification, validated BPMDs remain the recommended standard for office and out-of-office BP measurement to be used in hypertension diagnosis and management worldwide.
Patients with implanted pacemakers or implantable cardioverter defibrillators with pacing functio... more Patients with implanted pacemakers or implantable cardioverter defibrillators with pacing function were recruited from the Cardiac Health Institute and Macquarie Heart clinics. Exclusion criteria included unstable angina, previous myocardial infarction within the last 12 months of the study, and uncontrolled congestive heart failure. A total of 52 subjects (age 40-93 years, 11 female) entered the study, and all were included in the analysis. The study protocol was approved by Macquarie University's Human Ethics Committee and written consent to participate in the study was obtained from all subjects.
Aortic pulse wave velocity (PWV), calculated from pulse transit time (PTT) using 2 separate pulse... more Aortic pulse wave velocity (PWV), calculated from pulse transit time (PTT) using 2 separate pulse recordings over a known distance, is a significant biomarker of cardiovascular risk. This study evaluates a novel method of determining PTT from waveform decomposition of central aortic pressure using a single pulse measurement. Aortic pressure was estimated from a transformed radial pulse and decomposed into forward and backward waves using a triangular flow wave. Pulse transit time was determined from cross-correlation of forward and backward waves. Pulse transit time, representing twice the PTT between 2 specific sites, was compared with independent measurements of carotid-femoral PTT in a cohort of 46 subjects (23 females; age 57Ϯ14 years). Linear regression between measured PTT (y; milliseconds) and calculated PTT (x; milliseconds) was yϭ1.05xϪ2.1 (rϭ0.67; PϽ0.001). This model was tested in a separate group of 44 subjects (21 females; age 55Ϯ14 years) by comparing measured carotid-femoral PWV (y; meters per second) and PWV calculated using the estimated value of PTT (eTR/2) and carotid femoral distance (x; meters per second; yϭ1.21xϪ2.5; rϭ0.82; PϽ0.001). Findings indicate that the time lag between the forward and backward waves obtained from the decomposition of aortic pressure wave can be used to determine PWV along the aortic trunk and shows good agreement with carotid-femoral PWV. This technique can be used as a noninvasive and nonintrusive method for measurement of aortic PWV using a single pressure recording.
Central arterial waveforms can be estimated non-invasively from the combination of peripheral blo... more Central arterial waveforms can be estimated non-invasively from the combination of peripheral blood pressure and peripheral pulse waveform by use of a Transfer Function (TF), or directly measured by tonometry of the centrally located arteries such as the carotid artery . TFs allow waveforms from one part of the vascular system to be mathematically transformed into a waveform at another location within the system, most commonly from a peripheral artery with a readily accessible pulse such as the radial artery to a central artery, such as the ascending aorta. From these synthesized central waveforms, central hemodynamic indices such as cSBP and cAIx can then be extracted. Generalized TFs (gTF) are derived from ensemble-averaged Individualized TFs (iTF), and are widely used in adult hemodynamic research and have an emerging
Objectives: Arterial stiffness index β and cardio-ankle vascular index (CAVI) are widely accepted... more Objectives: Arterial stiffness index β and cardio-ankle vascular index (CAVI) are widely accepted to quantify the intrinsic exponent (β0) of the BP-diameter relationship. CAVI and β assume an exponential relationship between pressure (P) and diameter (d). We aim (1) to demonstrate that, under this assumption, β and CAVI as currently implemented are inherently BP-dependent; and (2) to provide corrected, BP-independent forms of CAVI and β. 1) , usually reference pressure (Pref) and reference diameter (dref) are substituted with diastolic BP and diameter to accommodate measurements. Consequently, the resulting exponent is not equal to the pressure-independent β0. CAVI does not only suffer from this "reference pressure" effect, but also from the approximation of 𝑑P 𝑑d . For example, assuming β0=7, an increase of systolic/diastolic BP from 110/70 to 170/120 mmHg increased β by 8.1% and CAVI by 14.3%. We derived corrected forms of β and of CAVI (CAVI0) that indeed did not change with BP and represent the pressure-independent β0. To substantiate the BP effect on CAVI in a typical follow-up study, we realistically simulated patients (n=161) before and following BP-lowering "treatment" (assuming no follow-up change in intrinsic β0 and therefore in actual P-d relationship). Lowering BP from 160±14/111±11 to 120±15/79±11 mmHg (p<0.001) resulted in a significant CAVI decrease (8.1±2.0 to 7.7±2.1, p=0.008); CAVI0 did not change (9.8±2.4 and 9.9±2.6, p=0.499). Conclusions: β and CAVI as currently implemented are inherently BP-dependent, potentially leading to erroneous conclusions in arterial stiffness trials. BPindependent forms are presented to readily overcome this problem.
Elevated central aortic pressure indices (e.g., systolic pressure and pulse pressure) predict car... more Elevated central aortic pressure indices (e.g., systolic pressure and pulse pressure) predict cardiovascular (CV) events and mortality in addition to structural changes (e.g., left ventricular hypertrophy, carotid intima-media thickness and reduced glomerular filtration rate). These elevated risks have been shown in multiple studies to be superior to, and in others, at least as high as that associated with brachial pressures. Threshold values for the diagnosis of elevated central arterial pressures have been defined and can be considered target goals of treatment. Measurements of central arterial pressures can be incorporated into the current approaches to hypertension management utilizing currently available non-invasive devices that measure central pressures during the measurement of brachial BP. The objective of this review is to outline the rationale and evidence supporting incorporation of central aortic pressure monitoring into the care of patients with hypertension.
ObjectivesThe aim of this study was to explore the risk of target organ damage (TOD) in different... more ObjectivesThe aim of this study was to explore the risk of target organ damage (TOD) in different groups based on carotid-femoral pulse wave velocity (cfPWV) and central aortic blood pressure (CBP) in different populations.MethodsThe study cohort was divided into four groups according to the status of cfPWV and CBP [Group (cfPWV/CBP): high cfPWV and high CBP; Group (cfPWV): high cfPWV and normal CBP; Group (CBP): normal cfPWV and high CBP; Group (control): normal cfPWV and normal CBP]. TOD was determined by the assessment of carotid intima-media thickness (CIMT) abnormality, chronic kidney disease (CKD), microalbuminuria, and left ventricular hypertrophy (LVH).ResultsA total of 1,280 patients (mean age 53.14 ± 12.76 years, 64.1% male patients) were recruited in this study. Regarding Group (control) as reference, LVH was significantly higher in Group (cfPWV) and Group (CBP) [OR 2.406, 95% CI (1.301–4.452), P < 0.05; OR 2.007, 95% CI (1.335–3.017), P < 0.05]; microalbuminuria wa...
ObjectiveAim of this study was to evaluate the associations of non-invasive central aortic and pe... more ObjectiveAim of this study was to evaluate the associations of non-invasive central aortic and peripheral (brachial) blood pressure (BP) for Hypertension-mediated organ damage (HMOD) and atherosclerotic cardiovascular disease (ASCVD) risk.MethodsWe evaluated associations of HMOD with 24-h ambulatory blood pressure monitoring (ABPM) of central aortic and peripheral BP indices in patients with primary hypertension and presence of several cardiovascular risk factors. BP measurements were performed by means of a non-invasive automated oscillometric device (Mobil-O-Graph). HMOD was defined as the presence of carotid intima-media thickness (IMT) above normal values and/or carotid plaque, left ventricular hypertrophy (LVH), and/or renal abnormalities as assessed by urine albumin/creatinine ratio above normal values and/or estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2.ResultsIn the study cohort of 273 (age 55.2 ± 13.4 years, 71.8% male) patients with primary hyperten...
The arterial pulse wave is a physiological signal which can reflect the function of the human car... more The arterial pulse wave is a physiological signal which can reflect the function of the human cardiovascular system. Owing to the measurement being convenient and safe, radial pulse waves have been often used in noninvasive monitoring of human health, which can further reflect the health status of the cardiovascular system, including information of the aorta and peripheral arteries. Moreover, radial pulse waves can assist clinical diagnosis in the prevention and treatment of cardiovascular disease. This paper systematically reviews the progress in analysis of pulse wave analysis, including pulse wave acquisition, waveform processing, pattern classification, parameter estimation, and clinical applications. In terms of waveform acquisition, this paper reviews a variety of methods to obtain radial pulse waves, including tonometry, photoplethysmography, ultrasound manometry, and flexible tactile pressure sensors. In the aspect of waveform processing, this paper summarizes the methods of radial pulse waves preprocessing and feature extraction. With the rapid development of machine learning and deep learning algorithms, radial pulse waves can be used to identify the status of human cardiovascular systems and to estimate parameters related to cardiovascular function. This paper also discusses the applications of radial pulse waves in clinical practice, including cardiovascular function evaluation and pulse diagnosis in traditional Chinese medicine. Some open-source databases and analysis software are also listed. The current development trend, challenges, and future directions of analysis of radial pulse waves are also offered. INDEX TERMS Radial artery, pulse wave, waveform processing, feature extraction, pattern classification, parameter estimation.
BACKGROUND Aortic stiffness as measured by carotid–femoral pulse wave velocity (cfPWV) is known t... more BACKGROUND Aortic stiffness as measured by carotid–femoral pulse wave velocity (cfPWV) is known to depend on blood pressure (BP), and this dependency may change with age. Therefore, the hydrostatic BP gradient resulting from a change in body posture may elicit a cfPWV change that is age-dependent. We aimed to analyze the relationship between BP gradient—induced by head-up body tilting—and related changes in cfPWV in individuals of varying age. METHODS cfPWV and other hemodynamic parameters were measured in 30 healthy individuals at a head-up tilt of 0° (supine), 30°, and 60°. At each angle, the PWV gradient and resulting cfPWV were also estimated (predicted) by assuming a global nonlinear, exponential, pressure–diameter relationship characterized by a constant β0, and taking into account that (diastolic) foot-to-foot cfPWV acutely depends on diastolic BP. RESULTS cfPWV significantly increased upon body tilting (8.0 ± 2.0 m/s supine, 9.1 ± 2.6 m/s at 30°, 9.5 ± 3.2 m/s at 60°, P for ...
Arterial stiffness increases through life due to changes in smooth muscle and endothelial functio... more Arterial stiffness increases through life due to changes in smooth muscle and endothelial function, and alteration of the extracellular matrix through elastin degeneration, collagen cross-linking, and calcification. These processes occur with age and are accelerated in certain diseases including hypertension, diabetes mellitus, and end-stage renal failure . Arterial stiffness as a predictor of cardiovascular disease particularly in the elderly [2] has been receiving increasing interest in preventive health care. The association between cardiovascular disease risk factors and measures of arterial stiffness has been demonstrated in large-population studies . Arterial stiffness has been linked to vascular morbidity and mortality in cohorts with hypertension [6,7], end-stage renal disease [8], and type 2 diabetes mellitus . There is increasing recognition that the interrelations between arterial stiffness and cardiovascular events are mediated by microvascular remodelling and obliteration . Human and animal studies have evidenced arteriolar remodelling and capillary rarefaction in early stages of hypertension . The possibility that the microcirculatory impairment may occur early in the onset of increasing arterial stiffness underlines the importance of monitoring microcirculation for more effective preventive and therapeutic measures .
The retina provides a non-invasive window to monitor microvascular circulation. Carotid-femoral P... more The retina provides a non-invasive window to monitor microvascular circulation. Carotid-femoral Pulse Wave Velocity (cfPWV) is an indicator of large artery stiffness and is associated with systemic cardiovascular diseases. This study investigates whether Retinal artery PWV (rPWV) reflects cfPWV changes in an elderly cohort. Methods: A total of 37 elderly participants (28 female, age 79 ± 5 years) were studied. Participants with a history of diabetes, glaucoma, and any neurological or eye-related disorders were excluded. Twenty four subjects were taking antihypertensive medication. A 60-s recording of retinal arterial diameter changes were captured (25 Hz frame rate, Dynamic Vessel Analyzer). Systolic blood pressure, Diastolic Blood Pressure (DBP), cfPWV and Intraocular Pressure (IOP) were measured. A customwritten algorithm was used to extract pulse amplitudes from retinal arterial diameters within one-and three-disc diameters from the optic disc. rPWV was designated as the ratio of the distance between two sites along the artery to the time delay between pulses. Predictors of rPWV were assessed by linear regression and parameter selection techniques. Results: There was a positive correlation between rPWV and cfPWV (Pearson's correlation coefficient 0.82, p < 0.001). In parameter selection models, cfPWV, transmural pressure (DBP-IOP), male sex, and IOP were isolated as predictors of rPWV. This study found a positive correlation between rPWV and cfPWV in an elderly cohort. This indicates that microvessel remodelling that parallels large vessel remodelling is able to be detected using rPWV measurement. Further longitudinal studies are required to elucidate the predictive value of screening rPWV in systemic cardiovascular abnormalities.
n Z 30) was also associated with gothic arch (p Z 0.01), and dilated ascending aorta but with no ... more n Z 30) was also associated with gothic arch (p Z 0.01), and dilated ascending aorta but with no aortic root dilation (p Z 0.02). On multivariate regression analysis, gothic arch was indeed associated with coarctation and stenosis, and also with non-coronary valve fusion pattern (p Z 0.03). Patients with aortic regurgitation tended to have larger aortas (p Z 0.005). The presence of aortic coarctation and stenosis may influence the amount of dilation and the overall arch architecture in BAV patients. Patients with BAV present profoundly different morphological phenotypes depending on the presence/absence of aortic coarctation (Fig. ).
Aortic pulse wave velocity is a worldwide accepted index to evaluate aortic stiffness and can be ... more Aortic pulse wave velocity is a worldwide accepted index to evaluate aortic stiffness and can be assessed noninvasively by several methods. This study sought to determine if commonly used noninvasive devices can all accurately estimate aortic pulse wave velocity. Pulse wave velocity was estimated in 102 patients (aged 65±13 years) undergoing diagnostic coronary angiography with 7 noninvasive devices and compared with invasive aortic pulse wave velocity. Devices evaluating carotid-femoral pulse wave velocity (Complior Analyse, PulsePen ET, PulsePen ETT, and SphygmoCor) showed a strong agreement between each other ( r >0.83) and with invasive aortic pulse wave velocity. The mean difference ±SD with the invasive pulse wave velocity was −0.73±2.83 m/s ( r =0.64) for Complior-Analyse: 0.20±2.54 m/s ( r =0.71) for PulsePen-ETT: −0.04±2.33 m/s ( r =0.78) for PulsePen ET; and −0.61±2.57 m/s ( r =0.70) for SphygmoCor. The finger-toe pulse wave velocity, evaluated by pOpmètre, showed only ...
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Papers by Alberto Avolio