Development of a 1D Model for Assessing the Aortic Root Pressure Drop With Viscosity and Compliance

2013 ◽  
Author(s):  
Hossein Mohammadi ◽  
Raymond Cartier ◽  
Rosaire Mongrain
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Flow Rate ◽  
Aortic Root ◽  
Blood Flow Rate ◽  
Effective Orifice Area ◽  
Valvular Heart Diseases ◽  
1D Model

Aging and some pathologies such as arterial hypertension, diabetes, hyperglycemia, and hyperinsulimenia cause some geometrical and mechanical changes in the aortic valve microstructure. Cupsal thickening and lost of extensibility (increasing stiffness) are the consequences of these changes in the aortic valve which have a negative impact on the function of the valve [1]. The most frequent form of diseases of the aortic valve is the calcific aortic stenosis which is responsible for 80% of the North American deaths due to valvular heart diseases [2]. In this pathology, calcified nodules on the valve leaflets occur which lead to the thickening and stiffening of the leaflets and restricting the natural motion of the valve which presents an increased resistance to forward blood flow during the ejection phase of the cardiac cycle. To reduce the mortality and morbidity from the aortic stenosis, clinical management and proper diagnosis are essential [3]. Tranvalvular pressure gradient (TPG) and the effective orifice area (EOA), the minimum cross sectional area of the blood flow across the stenosis, are the most commonly used indices for assessing the aortic stenosis [4]. Numerous studies have been done to relate the TPG across the stenosis to the blood flow rate and EOA. Gorlin (1951) was the first to establish a relationship between TPG and EOA [5]. Several studies have reported deviations in valve area calculation by using Gorlin formula. This formula was derived based on some assumptions such as rigid circular orifice, non viscous and steady flow, while valvular orifices are compliant and the flow through them is viscous and pulsatile [6]. Several corrections have been proposed. However, even with these improved formula, significant deviations are still reported [7]. Calark (1978), Bermejo et al (2002) and Garcia et al (2006), by presenting a theoretical model, tried to express TPG in terms of the blood flow rate and EOA [8–10]. None of these studies considered the effect of the aortic root compliance on TPG. Nobari et al reported that the stiffening of the aorta changes the pressure drop and affects the leaflets motion [11]. Therefore, the objective of this study is to develop a 1D model for assessing the aortic pressure drop for the transient viscous blood flow across the aortic stenosis, by taking into account the vessel wall compliance. The derived TPG will be expressed in terms of the surrogate variables which are anatomical and hemodynamic data meaningful and accessible for physicians.

scholarly journals Comparison of the hemodynamic parameters of transaortic blood flow in patients with aortic stenosis depending on the bicuspid or tricuspid valve structure

2020 ◽  
Vol 24 (4) ◽  
pp. 74-80
Author(s):  
V. V. Bazylev ◽  
R. M. Babukov ◽  
F. L. Bartosh ◽  
A. V. Gorshkova
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Effective Area ◽  
Effective Orifice Area ◽  
Hemodynamic Parameters ◽  
Structure Comparison ◽  
Area Index ◽  
Orifice Area ◽  
Echocardiographic Study

Purpose: comparison of hemodynamic parameters of transaortic blood flow in patients with aortic stenosis depending on the bivalve or tricuspid structure of the aortic valve.Materials and methods. A study of 180 patients with isolated aortic valve stenosis (AC) with two – and threeleaf structure was conducted. Patients were ranked into 3 comparison subgroups by the area of the effective AC opening from 4 to 1.5 cm2; 1.5 to 1 cm2 and less than 1 cm2. An echocardiographic study was performed with the calculation of all the necessary parameters for the study.Results. The comparison subgroups were comparable in terms of effective orifice area (AVA), effective orifice area index (IAVA), body mass index (BMI), LV UO index, and LV FV (p > 0.05). However, the indicators Vmax, Gmean, and AT in patients with a bivalve AK structure in all comparison subgroups were significantly higher than in patients with a tricuspid structure. Comparison subgroup with AVA from 4 to 1.5 cm2: Vmax 2.8 ± 9 m/s and 2.5 ± 6 m/s p = 0.02. Gmean 18.6 ± 7.2 mm Hg and 15 ± 6 mm Hg p = 0.03, AT 82 ± 12 ms and 70 ± 10 ms p = 0.002. Comparison subgroup with AVA from 1.5 to 1 cm2: Vmax 3.7 ± 0.8 m/s and 3.5 ± 0.6 m/s p = 0.02. Average transaortic gradient 37 ± 10 mm Hg and 29 ± 5 mm Hg p = 0.04, AT 103 ± 11 ms and 94 ± 10 ms p = 0.02. Comparison subgroup with an effective area of less than 1 cm2: Vmax 5.7 ± 1.2 m/s and 4.7 ± 0.7 m/s p = 0.001, Gmean 54 ± 15 and 43 ± 11 mm Hg p < 0.001, AT 127 ± 20 ms and 112 ± 10 ms p = 0.002.Conclusion. Echocardiographic indicators of Vmax and Gmean in patients with bivalve AC structure have higher values than in patients with tricuspid AC structure with a comparable opening area.

The effect of pressure drop stabilization in arteries during variations in blood flow rate

1993 ◽  
Vol 148 (3) ◽  
pp. 285-294 ◽  
Author(s):  
V. M. KHAYUTIN ◽  
V. P. NIKOLSKY ◽  
A. N. ROGOZA ◽  
E. V. LUKOSHKOVA
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Effect Of Pressure

STEADY VORTICES IN ARTERIAL FLOWS

2004 ◽  
Vol 04 (04) ◽  
pp. 579-587
Author(s):  
MARIUSZ R. SLAWOMIRSKI ◽  
GIOVANNI PALLOTTI ◽  
PAOLO PETTAZZONI
Keyword(s):  
Blood Flow ◽  
Stress State ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Additional Stress ◽  
Two Dimensional ◽  
Progressive Development ◽  
Steady Vortices

Many authors describe the movement in veins and arteries applying the Poisseuille flow pattern, according to which all streamlines are parallel to the walls of vessels, and the blood flow rate is proportional to the pressure drop. The presence of vortices may imply two-dimensional stress state in the wall of the vessel. It may be suggest that the additional stress may increase the probability to injure the cells of endothelium. The progressive development of atheroma sedimentation in the vicinity of bifurcations of arteries confirms the hypothesis mentioned above.

scholarly journals Aortic valve function post-replacement of severe aortic stenosis by transcatheter procedure versus surgery: a systematic review and metanalysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charbel Abi Khalil ◽  
Barbara Ignatiuk ◽  
Guliz Erdem ◽  
Hiam Chemaitelly ◽  
Fabio Barilli ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Randomized Clinical Trials ◽  
Severe Aortic Stenosis ◽  
Paravalvular Leak ◽  
Effective Orifice Area ◽  
Surgical Aortic Valve Replacement ◽  
Transcatheter Heart Valve

AbstractTranscatheter aortic valve replacement (TAVR) has shown to reduce mortality compared to surgical aortic valve replacement (sAVR). However, it is unknown which procedure is associated with better post-procedural valvular function. We conducted a meta-analysis of randomized clinical trials that compared TAVR to sAVR for at least 2 years. The primary outcome was post-procedural patient-prosthesis-mismatch (PPM). Secondary outcomes were post-procedural and 2-year: effective orifice area (EOA), paravalvular gradient (PVG) and moderate/severe paravalvular leak (PVL). We identified 6 trials with a total of 7022 participants with severe aortic stenosis. TAVR was associated with 37% (95% CI [0.51–0.78) mean RR reduction of post-procedural PPM, a decrease that was not affected by the surgical risk at inclusion, neither by the transcatheter heart valve system. Postprocedural changes in gradient and EOA were also in favor of TAVR as there was a pooled mean difference decrease of 0.56 (95% CI [0.73–0.38]) in gradient and an increase of 0.47 (95% CI [0.38–0.56]) in EOA. Additionally, self-expandable valves were associated with a higher decrease in gradient than balloon ones (beta = 0.38; 95% CI [0.12–0.64]). However, TAVR was associated with a higher risk of moderate/severe PVL (pooled RR: 9.54, 95% CI [5.53–16.46]). All results were sustainable at 2 years.

scholarly journals Impact of the Trifecta bioprosthetic valve in patients with low-flow severe aortic stenosis

2021 ◽  
Author(s):  
Tohru Takaseya ◽  
Atsunobu Oryoji ◽  
Kazuyoshi Takagi ◽  
Tomofumi Fukuda ◽  
Koichi Arinaga ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Severe Aortic Stenosis ◽  
Stroke Volume Index ◽  
Low Flow ◽  
Volume Index ◽  
Effective Orifice Area ◽  
Aortic Valve Area ◽  
Hemodynamic Performance ◽  
Mid Term Results

AbstractAortic stenosis (AS) is the most common valve disorder in advanced age. Previous reports have shown that low-flow status of the left ventricle is an independent predictor of cardiovascular mortality after surgery. The Trifecta bioprosthesis has recently shown favorable hemodynamic performance. This study aimed to evaluate the effect of the Trifecta bioprosthesis, which has a large effective orifice area, in patients with low-flow severe AS who have a poor prognosis. We retrospectively evaluated 94 consecutive patients with severe AS who underwent aortic valve replacement (AVR). Patients were divided into two groups according to the stroke volume index (SVI): low-flow (LF) group (SVI < 35 ml/m2, n = 22) and normal-flow (NF) group (SVI ≥ 35 ml/m2, n = 72). Patients’ characteristics and early and mid-term results were compared between the two groups. There were no differences in patients’ characteristics, except for systolic blood pressure (LF:NF = 120:138 mmHg, p < 0.01) and the rate of atrial fibrillation between the groups. A preoperative echocardiogram showed that the pressure gradient was higher in the NF group than in the LF group, but aortic valve area was similar. The Trifecta bioprosthesis size was similar in both groups. The operative outcomes were not different between the groups. Severe patient–prosthesis mismatch (PPM) (< 0.65 cm2/m2) was not observed in either of the groups. There were no significant differences in mid-term results between the two groups. The favorable hemodynamic performance of the Trifecta bioprosthesis appears to have the similar outcomes in the LF and NF groups. AVR with the Trifecta bioprosthesis should be considered for avoidance of PPM, particularly in AS patients with LV dysfunction.

The Effect of Furosemide on the Intrarenal Blood Flow Distribution in the Dog

1972 ◽  
Vol 50 (8) ◽  
pp. 774-783 ◽  
Author(s):  
Serge Carrière ◽  
Michel Desrosiers ◽  
Jacques Friborg ◽  
Michèle Gagnan Brunette
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Urine Volume ◽  
Flow Distribution ◽  
Blood Flow Rate ◽  
Initial Distribution ◽  
Blood Flow Distribution ◽  
Intrarenal Blood Flow ◽  
Femoral Blood ◽  
Furosemide Administration

Furosemide (40 μg/min) was perfused directly into the renal artery of dogs in whom the femoral blood pressure was reduced (80 mm Hg) by aortic clamping above the renal arteries. This maneuver, which does not influence the intrarenal blood flow distribution, produced significant decreases of the urine volume, natriuresis, Ccreat, and CPAH, and prevented the marked diuresis normally produced by furosemide. Therefore the chances that systemic physiological changes occurred, secondary to large fluid movements, were minimized. In those conditions, however, furosemide produced a significant increase of the urine output and sodium excretion in the experimental kidney whereas Ccreat and CPAH were not affected. The outer cortical blood flow rate (ml/100 g-min) was modified neither by aortic constriction (562 ± 68 versus 569 ± 83) nor by the subsequent administration of furosemide (424 ± 70). The blood flow rate of the outer medulla in these three conditions remained unchanged (147 ± 52 versus 171 ± 44 versus 159 ± 54). The initial distribution of the radioactivity in each compartment remained comparable in the three conditions. In parallel with the results from the krypton-85 disappearance curves, the autoradiograms, silicone rubber casts, and EPAH did not suggest any change in the renal blood flow distribution secondary to furosemide administration.

Abstract 17870: Hemodynamic Performance of Transcatheter Prosthetic Valve is Superior to that of Surgical Prosthetic Valve for Aortic Valve Stenosis with Small Aortic Root

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Koichi Maeda ◽  
Toru Kuratani ◽  
Kei Torikai ◽  
Isamu Mizote ◽  
Yasuhiro Ichibori ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Predictive Factor ◽  
Aortic Root ◽  
Prosthetic Valve ◽  
The Other ◽  
Effective Orifice Area ◽  
Orifice Area ◽  
Small Aortic Root ◽  
Hemodynamic Performance

Introduction: Surgical aortic valve replacement (SAVR) in a small aortic root is still challenging with regard to the surgical technique and prosthesis size selection, which often causes patient-prosthesis mismatch (PPM). On the other hand, because a prosthetic valve of transcatheter aortic valve replacement (TAVR) is tightly implanted inside a native valve, larger effective orifice area (EOA) may be gained. The aim of this study is to prove that hemodynamic performance after TAVR is superior to that after SAVR. Methods: 160 patients, who underwent SAVR (n=36; age 75.1±5.6 years) and TAVR (n=124; age 82.4±6.8 years) for aortic valve stenosis, were enrolled. Preoperative ECG-gated multi-slice CT (MSCT) and echocardiography immediately before a discharge were performed in all patients. PPM was defined as the effective orifice area index ≤0.85cm2/m2 and we compared and examined hemodynamic performance after TAVR and SAVR. Results: Although the mean body size was significantly smaller (p<.05) in TAVR than that in SAVR (1.44±0.15 vs 1.51±0.20 m2), there were no significant differences in the diameters of annulus (23.2±1.6 vs 23.3±2.8 mm), valsalva sinus (29.8±2.6 vs 29.9±4.4 mm), and ST junction (25.2±2.8 vs 24.8±3.5 mm) on preoperative MSCT findings. Postoperative echocardiography revealed significantly less Vmax (2.2±0.4 vs 2.5±0.5 m/s, p<.0001), less mean pressure gradient (10.1±3.6 vs 14.5±5.0 mmHg, p<.0001), and larger EOA (1.62±0.29 vs 1.45±0.36 cm2, p<.005) in TAVR compared to SAVR, respectively. Consequently, PPM was more frequently in SAVR compared to TAVR (33.3 vs 8.9%; p<.0007). In multivariate analysis in SAVR identified small ST junction with only predictive factor of PPM (odds ratio [OR], 2.08; 95% CI, 1.23-4.36; p<.005; area under the receiver-operating characteristic curve [AUC], 0.84). On the other hand, regarding TAVR, large BSA was only predictive factor of PPM (p<.05). Conclusions: The hemodynamic performance of transcatheter prosthetic valve is superior to that of surgical prosthetic valve in a patient with small aortic root, in particular, small ST junction. TAVR should be considered in patients with anticipated PPM if the surgical risk is similar to TAVR.

The Effect of Hematocrit on the Clearance of Small Molecules during Hemodialysis

1983 ◽  
Vol 6 (3) ◽  
pp. 127-130 ◽  
Author(s):  
C. Woffindin ◽  
N.A. Hoenich ◽  
D.N.S. Kerr
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Small Molecules ◽  
Flat Plate ◽  
Flow Rate ◽  
Distribution Curve ◽  
Blood Flow Rate ◽  
Hollow Fibre ◽  
Urea Clearance ◽  
Flow Rates

Data collected during the evaluation of a series of hemodialysers were analysed to see the effect of hematocrit on the clearance of urea and creatinine. All evaluations were performed on patients with a range of hematocrits with a mean close to 20%. The urea clearance of those in the upper half of the distribution curve (mean hematocrit 29.4%) was not significantly different from that of patients in the lower half of the distribution curve (mean hematocrit 16.9%) whether the clearance was studied at high or low blood flow rates and with hollow fibre or flat plate disposable hemodialysers. Likewise, there was no correlation between hematocrit and urea clearance by regression analysis. In contrast, the clearance of creatinine was affected by hematocrit being greater at lower hematocrit values. This difference was independent of blood flow rate and dialyser type and was confirmed by regression analysis.

scholarly journals A Simplified Model for Predicting Friction Factors of Laminar Blood Flow in Small-Caliber Vessels

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 75 ◽  
Author(s):  
Aikaterini Mouza ◽  
Olga Skordia ◽  
Ioannis Tzouganatos ◽  
Spiros Paras
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Friction Factor ◽  
Small Diameter ◽  
Numerical Data ◽  
Blood Flow Rate ◽  
Vessel Diameter ◽  
Simplified Model ◽  
Glycerol Solution ◽  
Fanning Friction Factor

The aim of this study was to provide scientists with a straightforward correlation that can be applied to the prediction of the Fanning friction factor and consequently the pressure drop that arises during blood flow in small-caliber vessels. Due to the small diameter of the conduit, the Reynolds numbers are low and thus the flow is laminar. This study has been conducted using Computational Fluid Dynamics (CFD) simulations validated with relevant experimental data, acquired using an appropriate experimental setup. The experiments relate to the pressure drop measurement during the flow of a blood analogue that follows the Casson model, i.e., an aqueous Glycerol solution that contains a small amount of Xanthan gum and exhibits similar behavior to blood, in a smooth, stainless steel microtube (L = 50 mm and D = 400 μm). The interpretation of the resulting numerical data led to the proposal of a simplified model that incorporates the effect of the blood flow rate, the hematocrit value (35–55%) and the vessel diameter (300–1800 μm) and predicts, with better than ±10% accuracy, the Fanning friction factor and consequently the pressure drop during laminar blood flow in healthy small-caliber vessels.

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