Hemodynamic effects of the human aorta arch with different inflow rate waveforms from the ascending aorta inlet: A numerical study

Biorheology ◽  
2021 ◽  
pp. 1-11
Author(s):  
Ying Chen ◽  
Yunmei Yang ◽  
Wenchang Tan ◽  
Liqin Fu ◽  
Xiaoyan Deng ◽  
...  
Keyword(s):  
Pulsatile Flow ◽  
Continuous Flow ◽  
Helical Flow ◽  
Ascending Aorta ◽  
Ventricular Assist Devices ◽  
Human Aorta ◽  
Inflow Rate ◽  
Hemodynamic Effects ◽  
Flow Strength ◽  
Relative Residence Time

BACKGROUND: Heart failure (HF) is a common disease globally. Ventricular assist devices (VADs) are widely used to treat HF. In contrast to the natural heart, different VADs generate different blood flow waves in the aorta. OBJECTIVE: To explore whether the different inflow rate waveforms from the ascending aorta generate far-reaching hemodynamic influences on the human aortic arch. METHODS: An aortic geometric model was reconstructed based on computed tomography data of a patient with HF. A total of five numerical simulations were conducted, including a case with the inflow rate waveforms from the ascending aorta with normal physiological conditions, two HF, and two with typical VAD support. The hemodynamic parameters, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and the strength of the helical flow, were calculated. RESULTS: In contrast to the natural heart, numerical simulation showed HF decreasing WSS and inducing higher OSI and RRT. Moreover, HF weakened helical flow strength. Pulsatile flow VADs will elevated the WSS, inducing some helical flow, while continuous flow VAD could not produce any helical flow. CONCLUSIONS: HF leads to an adverse hemodynamic environment by decreasing WSS and reducing the helical flow strength. Pulsatile flow VADs are more advantageous than the continuous flow VADs on hemodynamic effects. Thus, pulsatile flow VADs may be a better option for patients with HF.

Pulsatile Flow in Patients With a Novel Nonpulsatile Implantable Ventricular Assist Device

Circulation ◽  
2000 ◽  
Vol 102 (suppl_3) ◽  
Author(s):  
Evgenij V. Potapov ◽  
Matthias Loebe ◽  
Boris A. Nasseri ◽  
Hendryk Sinawski ◽  
Andreas Koster ◽  
...  
Keyword(s):  
Ejection Fraction ◽  
Pulsatile Flow ◽  
Transcranial Doppler ◽  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Doppler Signals ◽  
End Stage ◽  
Cranial Arteries

Background —Ventricular assist devices (VADs) are an accepted therapy for patients with end-stage heart failure. The implantable devices that are available produce a pulsatile flow and are very large. In 6 patients, beginning in November 1998, we started to use the continuous-flow implantable DeBakey VAD device, which weighs 93 g. To detect the flow in peripheral vessels, we measured transcranial Doppler signals in patients after implantation. Methods and Results —Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2-MHz probes (for the middle cranial arteries) in 4 patients for up to 12 weeks twice weekly after implantation. The blood velocity was measured, and the pulsation index (PI) calculated. The measured pump flow and rotations per minute were registered. The preoperative echocardiographic assessment values were compared with those acquired 6 weeks after implantation. The PI increased continually in all patients after VAD implantation, left ventricular (LV) ejection fraction did not improve, but right ventricular (RV) ejection fraction after implantation improved compared with preoperative values. The LV end-diastolic diameter after implantation decreased between 11% and 46% intraindividually. There was no correlation between PI and blood pressure or, except in 1 patient, between PI and blood flow through the VAD. Conclusions —The DeBakey VAD unloads the LV, which leads to a decrease in LV end-diastolic LV diameter and to the restoration of RV function. The unloaded LV and partially recovered RV provide a nearly physiological pulsatile flow despite the continuous flow of the VAD. Pulsatility is independent of peripheral vascular resistance. The first clinical experience with the DeBakey VAD was positive and has resulted in its continued use.

scholarly journals In Vitro Pulsatility Analysis of Axial-Flow and Centrifugal-Flow Left Ventricular Assist Devices

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J. Ryan Stanfield ◽  
Craig H. Selzman
Keyword(s):  
Pulsatile Flow ◽  
Continuous Flow ◽  
Axial Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Assist Devices ◽  
Centrifugal Pumps ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Flow Devices

Recently, continuous-flow ventricular assist devices (CF-VADs) have supplanted older, pulsatile-flow pumps, for treating patients with advanced heart failure. Despite the excellent results of the newer generation devices, the effects of long-term loss of pulsatility remain unknown. The aim of this study is to compare the ability of both axial and centrifugal continuous-flow pumps to intrinsically modify pulsatility when placed under physiologically diverse conditions. Four VADs, two axial- and two centrifugal-flow, were evaluated on a mock circulatory flow system. Each VAD was operated at a constant impeller speed over three hypothetical cardiac conditions: normo-tensive, hypertensive, and hypotensive. Pulsatility index (PI) was compared for each device under each condition. Centrifugal-flow devices had a higher PI than that of axial-flow pumps. Under normo-tension, flow PI was 0.98 ± 0.03 and 1.50 ± 0.02 for the axial and centrifugal groups, respectively (p < 0.01). Under hypertension, flow PI was 1.90 ± 0.16 and 4.21 ± 0.29 for the axial and centrifugal pumps, respectively (p = 0.01). Under hypotension, PI was 0.73 ± 0.02 and 0.78 ± 0.02 for the axial and centrifugal groups, respectively (p = 0.13). All tested CF-VADs were capable of maintaining some pulsatile-flow when connected in parallel with our mock ventricle. We conclude that centrifugal-flow devices outperform the axial pumps from the basis of PI under tested conditions.

scholarly journals S021011 Investigation of the Durability Test Method of Continuous-flow Ventricular Assist Devices under Pulsatile Flow

2011 ◽  
Vol 2011 (0) ◽  
pp. _S021011-1-_S021011-4
Author(s):  
Masahiro NISHIDA ◽  
Ryo KOSAKA ◽  
Osamu MARUYAMA ◽  
Takashi YAMANE ◽  
Takeshi OKUBO ◽  
...  
Keyword(s):  
Pulsatile Flow ◽  
Continuous Flow ◽  
Test Method ◽  
Ventricular Assist Devices ◽  
Durability Test ◽  
Ventricular Assist ◽  
Assist Devices

A numerical study on the flow of blood and the transport of LDL in the human aorta: the physiological significance of the helical flow in the aortic arch

2009 ◽  
Vol 297 (1) ◽  
pp. H163-H170 ◽  
Author(s):  
Xiao Liu ◽  
Fang Pu ◽  
Yubo Fan ◽  
Xiaoyan Deng ◽  
Deyu Li ◽  
...  
Keyword(s):  
Blood Flow ◽  
Aortic Arch ◽  
Concentration Polarization ◽  
Numerical Study ◽  
Helical Flow ◽  
Ascending Aorta ◽  
Arterial System ◽  
Human Aorta ◽  
Ldl Transport

It has been proposed that a mass transfer phenomenon called concentration polarization of low-density lipoproteins (LDLs) may occur in the arterial system and is likely involved in the localization of atherogenesis. To test the hypothesis that concentration polarization of LDL may be suppressed by the helical flow pattern in the human aorta, hence sparing the ascending aorta from atherosclerosis, the effects of aortic torsion, branching, curvature, and taper on blood flow and LDL transport in the lumen were simulated numerically under steady-state flow conditions using four aorta models constructed based on in vivo MRI slices. The results showed that it was the aortic torsion that induced the helical flow in the aortic arch, stabilizing the flow of blood in the aorta, and compensated the adverse effects of the aortic curvature on blood flow and LDL transport. The helical flow reduced the luminal surface LDL concentration in the aortic arch and probably played a role in suppressing severe polarization of LDL at the entrances of the three branches on the arch, hence, protecting them from atherogenesis. The taper of the aorta was another important feature of the aorta that further stabilized the flow of blood and delayed the attenuation of the helical flow, making it move beyond the arch and into the beginning part of the descending aorta. The results therefore may account for why the ascending aorta and the arch are relatively free of atherosclerosis.

Sign in / Sign up

Export Citation Format

Share Document