Empirical estimates of mean aortic pressure: advantages, drawbacks and implications for pressure redundancy

2002 ◽  
Vol 103 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Denis CHEMLA ◽  
Jean-Louis HÉBERT ◽  
Eduardo APTECAR ◽  
Jean-Xavier MAZOIT ◽  
Karen ZAMANI ◽  
...  
Keyword(s):  
Form Factor ◽  
Pulse Pressure ◽  
Wave Reflection ◽  
Diastolic Pressure ◽  
Augmentation Index ◽  
Aortic Pressure ◽  
Arterial System ◽  
Wave Amplification ◽  
Empirical Estimates ◽  
Alternative Formula

Mean arterial pressure (MAP) is estimated at the brachial artery level by adding a fraction of pulse pressure (form factor; = 0.33) to diastolic pressure. We tested the hypothesis that a fixed form factor can also be used at the aortic root level. We recorded systolic aortic pressure (SAP) and diastolic aortic pressure (DAP), and we calculated aortic pulse pressure (PP) and the time-averaged MAP in the aorta of resting adults (n = 73; age 43±14 years). Wave reflection was quantified using the augmentation index. The aortic form factor (range 0.35-0.53) decreased with age, MAP, PP and augmentation index (each P<0.001). The mean form factor value (0.45) gave a reasonable estimation of MAP (MAP = DAP+0.45PP; bias = 0±2mmHg), and the bias increased with MAP (P<0.001). An alternative formula (MAP = DAP+PP/3+5mmHg) gave a more precise estimation (bias = 0±1mmHg), and the bias was not related to MAP. This latter formula was consistent with the previously reported mean pulse wave amplification of 15mmHg, and with unchanged MAP and diastolic pressure from aorta to periphery. Multiple linear regression showed that 99% of the variability of MAP was explained by the combined influence of DAP and SAP, thus confirming major pressure redundancy. Results were obtained irrespective of whether the marked differences in heart period and extent of wave reflection between subjects were taken into account. In conclusion, the aortic form factor was strongly influenced by age, aortic pressure and wave reflection. An empirical formula (MAP = DAP+PP/3+5mmHg) that is consistent with mechanical principles in the arterial system gave a more precise estimate of MAP in the aorta of resting humans. Only two distinct pressure-powered functions were carried out in the (SAP, DAP, MAP, PP) four-pressure set.

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

scholarly journals Effects of aerobic, resistance and concurrent exercise on pulse wave reflection and autonomic modulation in men with elevated blood pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paulo Farinatti ◽  
Alex da Silva Itaborahy ◽  
Tainah de Paula ◽  
Walace David Monteiro ◽  
Mário F. Neves
Keyword(s):  
Blood Pressure ◽  
Wave Reflection ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Aortic Pressure ◽  
Elevated Blood Pressure ◽  
Autonomic Modulation ◽  
Elevated Blood ◽  
Pulse Wave Reflection ◽  
Concurrent Exercise

AbstractThe acute effects of exercise modes on pulse wave reflection (PWR) and their relationship with autonomic control remain undefined, particularly in individuals with elevated blood pressure (BP). We compared PWR and autonomic modulation after acute aerobic (AE), resistance (RE), and concurrent exercise (CE) in 15 men with stage-1 hypertension (mean ± SE: 34.7 ± 2.5 years, 28.4 ± 0.6 kg/m2, 133 ± 1/82 ± 2 mmHg). Participants underwent AE, RE, and CE on different days in counterbalanced order. Applanation tonometry and heart rate variability assessments were performed before and 30-min postexercise. Aortic pressure decreased after AE (− 2.4 ± 0.7 mmHg; P = 0.01), RE (− 2.2 ± 0.6 mmHg; P = 0.03), and CE (− 3.1 ± 0.5 mmHg; P = 0.003). Augmentation index remained stable after RE, but lowered after AE (− 5.1 ± 1.7%; P = 0.03) and CE (− 7.6 ± 2.4% P = 0.002). Systolic BP reduction occurred after CE (− 5.3 ± 1.9 mmHg). RR-intervals and parasympathetic modulation lowered after all conditions (~ 30–40%; P < 0.05), while the sympathovagal balance increased after RE (1.2 ± 0.3–1.3 ± 0.3 n.u., P < 0.05). Changes in PWR correlated inversely with sympathetic and directly with vagal modulation in CE. In conclusion, AE, RE, and CE lowered central aortic pressure, but only AE and CE reduced PWR. Overall, those reductions related to decreased parasympathetic and increased sympathetic outflows. Autonomic fluctuations seemed to represent more a consequence than a cause of reduced PWR.

Use of pulse pressure method for estimating total arterial compliance in vivo

1999 ◽  
Vol 276 (2) ◽  
pp. H424-H428 ◽  
Author(s):  
N. Stergiopulos ◽  
P. Segers ◽  
N. Westerhof
Keyword(s):  
Pulse Pressure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Lower Limbs ◽  
Pressure Method ◽  
Total Arterial Compliance ◽  
The Difference ◽  
Pulse Pressure Method

We determined total arterial compliance from pressure and flow in the ascending aorta of seven anesthetized dogs using the pulse pressure method (PPM) and the decay time method (DTM). Compliance was determined under control and during occlusion of the aorta at four different locations (iliac, renal, diaphragm, and proximal descending thoracic aorta). Compliance of PPM gave consistently lower values (0.893 ± 0.015) compared with the compliance of DTM (means ± SE; r = 0.989). The lower compliance estimates by the PPM can be attributed to the difference in mean pressures at which compliance is determined (mean pressure, 81.0 ± 3.6 mmHg; mean diastolic pressure, over which the DTM applies, 67.0 ± 3.6 mmHg). Total arterial compliance under control conditions was 0.169 ± 0.007 ml/mmHg. Compliance of the proximal aorta, obtained during occlusion of the proximal descending aorta, was 0.100 ± 0.007 ml/mmHg. Mean aortic pressure was 80.4 ± 3.6 mmHg during control and 102 ± 7.7 mmHg during proximal descending aortic occlusion. From these results and assuming that upper limbs and the head contribute as little as the lower limbs, we conclude that 60% of total arterial compliance resides in the proximal aorta. When we take into account the inverse relationship between pressure and compliance, the contribution of the proximal aorta to the total arterial compliance is even more significant.

scholarly journals Effects of pacing modality on noninvasive assessment of heart rate dependency of indices of large artery function

2016 ◽  
Vol 121 (3) ◽  
pp. 771-780 ◽  
Author(s):  
Isabella Tan ◽  
Hosen Kiat ◽  
Edward Barin ◽  
Mark Butlin ◽  
Alberto P. Avolio
Keyword(s):  
Heart Rate ◽  
Arterial Stiffness ◽  
Pulse Pressure ◽  
Wave Reflection ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Large Artery ◽  
Rate Dependency ◽  
Wave Reflections

Studies investigating the relationship between heart rate (HR) and arterial stiffness or wave reflections have commonly induced HR changes through in situ cardiac pacing. Although pacing produces consistent HR changes, hemodynamics can be different with different pacing modalities. Whether the differences affect the HR relationship with arterial stiffness or wave reflections is unknown. In the present study, 48 subjects [mean age, 78 ± 10 (SD), 9 women] with in situ cardiac pacemakers were paced at 60, 70, 80, 90, and 100 beats per min under atrial, atrioventricular, or ventricular pacing. At each paced HR, brachial cuff-based pulse wave analysis was used to determine central hemodynamic parameters, including ejection duration (ED) and augmentation index (AIx). Wave separation analysis was used to determine wave reflection magnitude (RM) and reflection index (RI). Arterial stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV). Pacing modality was found to have significant effects on the HR relationship with ED ( P = 0.01), central aortic pulse pressure ( P = 0.01), augmentation pressure ( P < 0.0001), and magnitudes of both forward and reflected waves ( P = 0.05 and P = 0.003, respectively), but not cfPWV ( P = 0.57) or AIx ( P = 0.38). However, at a fixed HR, significant differences in pulse pressure amplification ( P < 0.001), AIx ( P < 0.0001), RM ( P = 0.03), and RI ( P = 0.03) were observed with different pacing modalities. These results demonstrate that although the HR relationships with arterial stiffness and systolic loading as measured by cfPWV and AIx were unaffected by pacing modality, it should still be taken into account for studies in which mixed pacing modalities are present, in particular, for wave reflection studies.

Estimation of total arterial compliance: an improved method and evaluation of current methods

1986 ◽  
Vol 251 (3) ◽  
pp. H588-H600 ◽  
Author(s):  
Z. Liu ◽  
K. P. Brin ◽  
F. C. Yin
Keyword(s):  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Arterial System ◽  
Windkessel Model ◽  
Total Arterial Compliance ◽  
Improved Methods ◽  
Mean Aortic Pressure

Determination of arterial compliance in vivo has long interested physiologists. Most current methods for estimating this parameter assume that compliance is constant, i.e., that arterial pressure-volume (P-V) relations are linear, and they also assume that diastolic aortic pressure decay is an exponential function of time. Both of these assumptions, however, are questionable. This study proposes improved methods of estimating compliance based on a Windkessel model of the arterial system but which utilize the area under the pressure tracing rather than the waveform itself. Formulations accounting for both linear and three hypothetical nonlinear arterial P-V relations (exponential, logarithmic, and parabolic) are presented. Data from patients with congestive heart failure and hypertension are used for illustration. Compliances assuming linear P-V relations are reasonably close to those assuming nonlinear P-V relations only at mean aortic pressure. At end-diastolic pressure the linear assumption underestimates and at peak systolic it overestimates the compliances obtained assuming nonlinear P-V relations. The simpler linear assumption still allows a first approximation to compliance, but we show that existing methods for obtaining compliance under this assumption have severe theoretical as well as practical shortcomings. Our proposed method avoids these shortcomings primarily because deviations from an exact exponential form of the pressure wave have less influence on these compliance estimates than currently used methods.

Progressive Resistance Training Without Volume Increases Does Not Alter Arterial Stiffness and Aortic Wave Reflection

2007 ◽  
Vol 232 (9) ◽  
pp. 1228-1235 ◽  
Author(s):  
Darren P. Casey ◽  
Darren T. Beck ◽  
Randy W. Braith
Keyword(s):  
Resistance Training ◽  
Arterial Stiffness ◽  
Pressure Wave ◽  
Wave Reflection ◽  
Augmentation Index ◽  
Aortic Pressure ◽  
Control Group ◽  
Training Volume ◽  
Leg Extension ◽  
Peripheral Arterial

Endurance exercise is efficacious in reducing arterial stiffness. However, the effect of resistance training (RT) on arterial stiffening is controversial. High-intensity, high-volume RT has been shown to increase arterial stiffness in young adults. We tested the hypothesis that an RT protocol consisting of progressively higher intensity without concurrent increases in training volume would not elicit increases in either central or peripheral arterial stiffness or alter aortic pressure wave reflection in young men and women. The RT group ( n = 24; 21 ± 1 years) performed two sets of 8–12 repetitions to volitional fatigue on seven exercise machines on 3 days/week for 12 weeks, whereas the control group ( n = 18; 22 ± 1 years) did not perform RT. Central and peripheral arterial pulse wave velocity (PWV), aortic pressure wave reflection (augmentation index; AIx), brachial flow–mediated dilation (FMD), and plasma levels of nitrate/nitrite (NOx) and norepinephrine (NE) were measured before and after RT. RT increased the one-repetition maximum for the chest press and the leg extension ( P < 0.001). RT also increased lean body mass ( P < 0.01) and reduced body fat (%; P < 0.01). However, RT did not affect carotid-radial, carotid-femoral, and femoral-distal PWV (8.4 ± 0.2 vs. 8.0 ± 0.2 m/sec; 6.5 ± 0.1 vs. 6.3 ± 0.2 m/sec; 9.5 ± 0.3 vs. 9.5 ± 0.3 m/sec, respectively) or AIx (2.5% ± 2.3% vs. 4.8% ± 1.8 %, respectively). Additionally, no changes were observed in brachial FMD, NOx, NE, or blood pressures. These results suggest that an RT protocol consisting of progressively higher intensity without concurrent increases in training volume does not increase central or peripheral arterial stiffness or alter aortic pressure wave characteristics in young subjects.

scholarly journals Leukocyte telomerase concentration is inversely associated with central wave reflection in patients with hypertension

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
O S Pavlova ◽  
T L Denisevich ◽  
M I Belskaya ◽  
E V Shafranovskaya ◽  
S E Ogurtsova ◽  
...  
Keyword(s):  
Family History ◽  
Cardiovascular Diseases ◽  
Arterial Stiffness ◽  
Telomere Length ◽  
Pulse Pressure ◽  
Wave Reflection ◽  
Augmentation Index ◽  
History Of ◽  
The Mean ◽  
Depressive Episodes

Abstract Introduction Telomere length and telomerase are biomarkers of aging and cardiovascular diseases. Arterial stiffness is associated with vascular age and higher risk of cardiovascular diseases. Decreased reparative cell's potential may cause vascular ageing and predispose to the progression of hypertension. Objective To determine association leukocyte telomerase concentration (TC) and relative telomere length (RTL) with arterial stiffness in hypertensive patients. Material and methods The study included 120 people (70 patients with uncomplicated arterial hypertension (AH) and 50 normotensive individuals). Mean age of hypertensives was 54.8±9.3 and of normotensives was 50.2±9.73 years. Dietary habits, smoking, level of physical activity, body mass index, waist circumference, presence of obesity, blood pressure (BP) level, family history of cardiovascular deseases, depressive episodes and psychological stress according the international questionnaires, glucose; cholesterol, angiotensin II, renin and aldosteron in blood were assessed in the participants. Aortic BP, aortic pulse pressure, augmentation index (AIx), AIx adjusted for heart rate 75 beats per minute (Aix@HR75), pulse wave velocity (PWV) were determined by the applanation tonometry. RTL of peripheral blood leukocytes was performed by real-time PCR. The leukocyte TC was measured using the enzyme immunoassay. Results There were no differences between patients with AH and normotensives in both leukocyte TC (4.9 (4.0; 8.0) versus 6.2 (4.1; 9.4), p=0.281) and RTL (0.94 (0.86; 1.0) versus 0.96 (0.83; 1.0), p=0.978). In hypertensive and normotensive groups the mean systolic aortic BP were 130.6±17,7 and 109.9±11.7 mmHg (p&lt;0.001), aortic pulse pressure – 41.5±9,7 and 33.6±10,4 mmHg (p&lt;0.001), Aix@HR75 – 16.0 (7.0; 28.0) and 27.0 (13.0; 35.0)% (p=0.004), PWV –7.9±1.4 and 8.1±1,7 m/s (p=0.409) respectively. In patients with AH the mean leukocyte TC was lower with an increased Aix@75 (&gt;25%) in contrast to the group of patients with normal Aix@75 (4.45 (3.9; 7.8) versus 7.97 (4.6; 10.0) ng/ml; p=0.043). Based on the multivariate logistic regression analysis independent factors influencing on the Aix@75 were leukocyte TC &lt;5 ng/ml with the family history of AH (OR=1.9, 95% CI: 1.1–3.4; p=0.036), the degree of AH combined with decreased salt sensitivity (OR=3.1; 95% CI: 1.3–7.5; p=0.010) and age (OR=1.2; 95% CI: 1.1–1.2; p=0.001). Conclusions Decrease of the leukocyte telomerase concentration associated with the raise of augmentation index in patient with uncomplicated AH. As a parameter of central wave reflection the augmentation index may considered as an early sign of biological and vascular aging in hypertension. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The state program of scientific research “Fundamental and applied sciences for medicine”

Repeated reflection of waves in the systemic arterial system

1993 ◽  
Vol 264 (1) ◽  
pp. H269-H281 ◽  
Author(s):  
D. S. Berger ◽  
J. K. Li ◽  
W. K. Laskey ◽  
A. Noordergraaf
Keyword(s):  
Wave Reflection ◽  
Aortic Pressure ◽  
Arterial System ◽  
Tube Length ◽  
Pharmacological Intervention ◽  
Forward Wave ◽  
Heart Tube ◽  
Complex Load ◽  
Backward Wave ◽  
Reflection Theory

Traditional analysis of pulse-wave propagation and reflection in the arterial system treats measured pressure and flow waves as the sum of a single forward wave (traveling away from the heart) and a single backward wave (traveling toward the heart). The purpose of this study was to develop a more general wave reflection theory that allows repeated reflection of these waves. The arterial system was modeled as a uniform viscoelastic tube terminating in a complex load with reflections occurring at the tube load interface and the heart tube interface. The resulting framework considers the forward wave to be the sum of an initial wave plus a series of antegrade waves. Similarly, the backward wave is the sum of a series of retrograde waves. This repeated reflection theory contains within it the traditional forward/backward wave reflection analysis as a special case. In addition, the individual antegrade and retrograde waves, at the tube entrance, are shown to be independent of the tube length. Aortic pressure and flow data, from dog experiments, were used to illustrate the phenomenon of repeated reflections. Alteration of the arterial system loading conditions, brought about through pharmacological intervention, affected the number and morphology of repeated waves. These results are compared with those found in traditional forward/backward reflection analysis.

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