Wave speed and reflections proximal to aneurism and stenosis of flexible tubes

Hacham, Wisam S.; Abdulla, Najdat Nashat; Al-Ammri, A. Salam; Khir, Ashraf W.

doi:10.1109/embc.2015.7318535

Cited by 4 publications

(5 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The size and shape of aneurysm and stenosis are based on the studies by Pape et al 16 and Chambers, 17 respectively, which have also been used in our earlier work. 18…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The speed, reflection and intensity of waves propagating in flexible tubes with aneurysm and stenosis: Experimental investigation

Hacham

Khir

2019

Proc Inst Mech Eng H

View full text Add to dashboard Cite

A localized stenosis or aneurysm is a discontinuity that presents the pulse wave produced by the contracting heart with a reflection site. However, neither wave speed ( c) in these discontinuities nor the size of reflection in relation to the size of the discontinuity has been adequately studied before. Therefore, the aim of this work is to study the propagation of waves traversing flexible tubes in the presence of aneurysm and stenosis in vitro. We manufactured different sized four stenosis and four aneurysm silicone sections, connected one at a time to a flexible ‘mother’ tube, at the inlet of which a single semi-sinusoidal wave was generated. Pressure and velocity were measured simultaneously 25 cm downstream the inlet of the respective mother tube. The wave speed was measured using the PU-loop method in the mother tube and within each discontinuity using the foot-to-foot technique. The stenosis and aneurysm dimensions and c were used to determine the reflection coefficient ( R) at each discontinuity. Wave intensity analysis was used to determine the size of the reflected wave. The reflection coefficient increased with the increase and decrease in the size of the aneurysm and stenosis, respectively. c increased and decreased within stenosis and aneurysms, respectively, compared to that of the mother tube. Stenosis and aneurysm induced backward compression and expansion waves, respectively; the size of which was related to the size of the reflection coefficient at each discontinuity, increases with smaller stenosis and larger aneurysms. Wave speed is inversely proportional to the size of the discontinuity, exponentially increases with smaller stenosis and aneurysms and always higher in the stenosis. The size of the compression and expansion reflected wave depends on the size of R, increases with larger aneurysms and smaller stenosis.

show abstract

“…The size and shape of aneurysm and stenosis are based on the studies by Pape et al 16 and Chambers, 17 respectively, which have also been used in our earlier work. 18…”

Section: Methodsmentioning

confidence: 99%

“…The size and shape of aneurysm and stenosis are based on the studies by Pape et al 16 and Chambers, 17 respectively, which have also been used in our earlier work. 18 Tensile testing. Estimation of the Young's modulus of elasticity (E) provides a possibility to calculate the wave speed by employing the M-K equation.…”

Section: Experimental Set-upmentioning

confidence: 99%

The speed, reflection and intensity of waves propagating in flexible tubes with aneurysm and stenosis: Experimental investigation

Hacham

Khir

2019

Proc Inst Mech Eng H

View full text Add to dashboard Cite

show abstract

“…From the Means–Korteweg equation, PWV was greater when the aortic diameter (r) was smaller 15 . Hacham et al 16 also reported that reflected wave intensity showed a negative correlation with the diameter in an elastic tube of stenosis model 16 . Thus, our findings suggest that the assessment of the aortic diameter is important for patients who undergo EVAR.…”

Section: Discussionmentioning

confidence: 96%

Reflected wave intensity increases based on aortic diameter after endovascular aortic therapy in a goat model

Takano

Iwai-Takano

Tsuboko

et al. 2021

Sci Rep

View full text Add to dashboard Cite

Reflected wave increases after endovascular aortic repair (EVAR) in patients with aortic aneurysm. This affects the left ventricular (LV) diastolic function and leads to a poor prognosis. This study aimed to evaluate the relationship between increased reflected wave amplitude and aortic diameter after EVAR. EVAR was performed in seven healthy goats. We assessed wave intensity (WI), aortic diameter, and stiffness parameter β. Moreover, we evaluated the relationship between negative reflected wave (NW, reflected waves toward the heart from the periphery by WI) and other parameters after EVAR. Results showed an increase in stiffness parameter β (3.5 ± 0.3 vs 15.9 ± 4.7, p = 0.018) and a decrease in the change of aortic diameter (6.9 ± 0.7 vs 2.7 ± 0.4%, p = 0.018) after EVAR. The NW was significantly amplified after EVAR from baseline (−589.8 ± 143.4 to − 1192.3 ± 303.7 mmHg-m/sec3, p = 0.043). The NW showed a significant correlation with maximum aortic diameter (R = 0.707, p = 0.038) and minimum aortic diameter (R = 0.724, p = 0.033). The reflected wave was enhanced after EVAR and was correlated to the aortic diameter at the stent-graft site. It is important to consider that patients with smaller aortic diameters in landing zone who undergo EVAR may develop LV dysfunction.

show abstract

“…Numerous theoretical aspects of reflection of the plane waves at surface boundaris of elastic media have been investigated unconsidering the effects of initial stresses [25][26][27][28][29][30]. Sing et al [31] have been investigated the effects of rotation on the reflection coefficients of dilatation waves.…”

Section: Introductionmentioning

confidence: 99%

Transverse waves incident at the free surface of an initially stressed dissipative half-space

Selim¹,

Gepreel²

2021

Phys. Scr.

View full text Add to dashboard Cite

In this work, an attempt is done to apply Biot`s incremental deformation theory to find out the effects of initial stresses on the reflected transverse waves (S-waves) at a free surface of dissipative half-space medium. Equations of motion and its corresponding solutions are derived in lights of Biot`s theory. The impact of initial stresses and medium`s dissipation on the reflected transverse wave are studied in detail. Numerical calculations carried out using Aswan geological crustal structure and the results are presented graphically. Numerical findings reveal that, the initial stresses and the medium dissipation effects the reflection coefficients of transverse wave considerably. In addition, it has been noted that, the phase velocity decreases considerably as the initial stress parameter increases. Since the crust of the Earth, , is dissipative and initially stressed medium, thus understanding the effects of these parameters may help seismologists to get accurate results of reflected seismic transverse wave at the surface of Earth crust.

show abstract

Wave speed and reflections proximal to aneurism and stenosis of flexible tubes

Cited by 4 publications

References 6 publications

The speed, reflection and intensity of waves propagating in flexible tubes with aneurysm and stenosis: Experimental investigation

The speed, reflection and intensity of waves propagating in flexible tubes with aneurysm and stenosis: Experimental investigation

Reflected wave intensity increases based on aortic diameter after endovascular aortic therapy in a goat model

Transverse waves incident at the free surface of an initially stressed dissipative half-space

Contact Info

Product

Resources

About