SIMULATION OF A CLOSED LOOP MODEL EQUIVALENT ELECTRONIC OF NORMAL CARDIOVASCULAR SYSTEM AND VALVULAR AORTIC STENOSIS

2020 ◽  
Vol 20 (01) ◽  
pp. 1950074
Author(s):  
AMINA HALAIMI ◽  
BOUALEM CHETTI ◽  
BOUALEM LARIBI ◽  
OMAR LABBADLIA
Keyword(s):  
Aortic Stenosis ◽  
Pressure Gradient ◽  
Effective Orifice Area ◽  
Loop Model ◽  
Orifice Area ◽  
Electrical Analogy ◽  
Mean Pressure ◽  
Valvular Aortic Stenosis ◽  
The Mean ◽  
Good Agreement

This work presents a developed zero-dimensional cardiovascular (CV) system model, based on an electrical analogy, with a detailed compartmental description of the heart and the main vascular circulation which is able to simulate normal and diseased conditions of CV system, especially the stenosis valvular aortic. To know the effect of each parameter on hemodynamics, the number of parameters is increased by adding more segments. The developed model consists of 14 compartments. The results show that the severity of aortic stenosis (AS) effect varies with the effective orifice area and the mean pressure gradient for the case of no AS; the effective orifice area is 4[Formula: see text]cm2 and the mean pressure gradient is 0[Formula: see text]mmHg, while for the case of mild AS, the effective orifice area is 1.5[Formula: see text]cm2 and the mean pressure gradient is 27.24[Formula: see text]mmHg. For the case of moderate AS, the effective orifice area is 1.0[Formula: see text]cm2 and the mean pressure gradient is 44.68[Formula: see text]mmHg. For the case of the severe AS, the effective orifice area is 0.61[Formula: see text]cm2 and the mean pressure gradient is 77.51[Formula: see text]mmHg. It is found that the developed model can estimate an accurate value of the effective orifice area for any value of mean pressure gradient in AS. The results obtained for the CV system under normal and diseased conditions show a good agreement compared to published results.

scholarly journals Use and success evaluation of percutaneous aortic balloon valvuloplasty in different hemodynamic entities of severe aortic stenosis in the TAVR era

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
K Piayda ◽  
A Wimmer ◽  
H Sievert ◽  
K Hellhammer ◽  
S Afzal ◽  
...  
Keyword(s):  
Heart Failure ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Aortic Valve Replacement ◽  
Pressure Gradient ◽  
Severe Aortic Stenosis ◽  
Primary Treatment ◽  
Low Flow ◽  
Mean Pressure ◽  
The Mean

Abstract Background In the era of transcatheter aortic valve replacement (TAVR), there is renewed interest in percutaneous balloon aortic valvuloplasty (BAV), which may qualify as the primary treatment option of choice in special clinical situations. Success of BAV is commonly defined as a significant mean pressure gradient reduction after the procedure. Purpose To evaluate the correlation of the mean pressure gradient reduction and increase in the aortic valve area (AVA) in different flow and gradient patterns of severe aortic stenosis (AS). Methods Consecutive patients from 01/2010 to 03/2018 undergoing BAV were divided into normal-flow high-gradient (NFHG), low-flow low-gradient (LFLG) and paradoxical low-flow low-gradient (pLFLG) AS. Baseline characteristics, hemodynamic and clinical information were collected and compared. Additionally, the clinical pathway of patients (BAV as a stand-alone procedure or BAV as a bridge to aortic valve replacement) was followed-up. Results One-hundred-fifty-six patients were grouped into NFHG (n=68, 43.5%), LFLG (n=68, 43.5%) and pLFLG (n=20, 12.8%) AS. Underlying reasons for BAV and not TAVR/SAVR as the primary treatment option are displayed in Figure 1. Spearman correlation revealed that the mean pressure gradient reduction had a moderate correlation with the increase in the AVA in patients with NFHG AS (r: 0.529, p<0.001) but showed no association in patients with LFLG (r: 0.145, p=0.239) and pLFLG (r: 0.030, p=0.889) AS. Underlying reasons for patients to undergo BAV and not TAVR/SAVR varied between groups, however cardiogenic shock or refractory heart failure (overall 46.8%) were the most common ones. After the procedure, independent of the hemodynamic AS entity, patients showed a functional improvement, represented by substantially lower NYHA class levels (p<0.001), lower NT-pro BNP levels (p=0.003) and a numerical but non-significant improvement in other echocardiographic parameters like the left ventricular ejection fraction (p=0.163) and tricuspid annular plane systolic excursion (TAPSE, p=0.066). An unplanned cardiac re-admission due to heart failure was necessary in 23.7% patients. Less than half of the patients (44.2%) received BAV as a bridge to TAVR/SAVR (median time to bridge 64 days). Survival was significantly increased in patients having BAV as a staged procedure (log-rank p<0.001). Conclusion In daily clinical practice, the mean pressure gradient reduction might be an adequate surrogate of BAV success in patients with NFHG AS but is not suitable for patients with other hemodynamic entities of AS. In those patients, TTE should be directly performed in the catheter laboratory to correctly assess the increase of the AVA. BAV as a staged procedure in selected clinical scenarios increases survival and is a considerable option in all flow states of severe AS. (NCT04053192) Figure 1 Funding Acknowledgement Type of funding source: None

scholarly journals Two-Year Clinical Follow-Up Assessment of the Novel Cingular Surgical Bovine Pericardial Valve

2021 ◽  
Vol 8 ◽  
Author(s):  
Jinmiao Chen ◽  
Minzhi Lv ◽  
Yuntao Lu ◽  
Jiahui Fu ◽  
Yingqiang Guo ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Prosthetic Valve Endocarditis ◽  
Effective Orifice Area ◽  
Clinical Safety ◽  
Clinical Events ◽  
Structural Valve Deterioration ◽  
Mean Pressure ◽  
The Mean ◽  
Hemodynamic Performance

Objectives: To evaluate the 2-year clinical safety and hemodynamic outcomes of the Cingular bovine pericardial bioprosthesis.Methods: A prospective, multicenter, single-arm trial was conducted in patients who required aortic or mitral valve replacement. From March 2016 to October 2017, 197 patients were implanted with the Cingular bovine pericardial valve at five sites in China. The clinical outcomes and hemodynamic performance were assessed through a 2-year follow-up. Clinical safety events were reviewed by an independent clinical events committee, and echocardiographic data were assessed by an independent core laboratory.Results: The mean age was 66.9 ± 4.9 years. The 2-year survival rate was 96.4%. A complete 2-year clinical follow-up was achieved in 189 of 190 survivors. No case of structural valve deterioration, major perivalvular leak, prosthetic valve endocarditis, or valve-related reoperation was seen. For the aortic valve, the mean pressure gradient observed was 12.5 ± 4.0 mm Hg, and the effective orifice area (EOA) was 2.0 ± 0.3 cm2. For the smaller size aortic valves, 19 mm and 21 mm, respective mean EOA values of 1.7 ± 0.2 cm2 and 1.8 ± 0.2 cm2 were found. The values for mean pressure gradient and mean EOA for mitral bioprostheses were 4.0 ± 1.4 mm Hg and 2.2 ± 0.3 cm2, respectively. There was no significant change between 1-year and 2-year hemodynamic performance.Conclusions: The Cingular bovine pericardial valve showed favorable clinical safety and hemodynamic outcomes over a 2-year follow-up. Further follow-up is required to validate the long-term durability.

scholarly journals Comparison of safety and haemodynamic performance between the Avalus™ stented aortic valve bioprosthesis and Magna™ valve in Japanese patients

2021 ◽  
Author(s):  
Naoki Tadokoro ◽  
Satsuki Fukushima ◽  
Yusuke Shimahara ◽  
Tetsuya Saito ◽  
Naonori Kawamoto ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Pressure Gradient ◽  
Pacemaker Implantation ◽  
Japanese Patients ◽  
Left Ventricular ◽  
Risk Scores ◽  
Effective Orifice Area ◽  
Significant Difference ◽  
Mean Pressure ◽  
The Mean

Abstract Objectives A new stented bovine pericardial valve (Avalus™) has been proven safe and effective with good hemodynamic performance in Western populations. However, its use in Japanese patients is poorly understood. We retrospectively compared the feasibility, safety, and valve haemodynamics between the Avalus™ and Magna™ valves in patients who underwent surgical aortic valve replacement (SAVR). Methods This study included 87 patients receiving an Avalus™ valve and 387 receiving a Magna™ valve. We evaluated adverse events, outcomes, and valve haemodynamics within 1 year postoperatively. There were no significant differences in any surgical risk scores. Results No in-hospital mortality occurred in the Avalus™ group, but two mortality events occurred in the Magna™ group. No pacemaker implantation for complete atrioventricular block was required in the Avalus™ group. There was no significant difference in in-hospital or clinical outcomes between the two groups until 1 year postoperatively. Left ventricular mass index reduction appeared to predominate in the Avalus™ over Magna™ group. There was no significant difference in the mean pressure gradient or effective orifice area of each valve size at 1 week or 1 year between the two groups, apart from the mean pressure gradient of the 23-mm valve at 1 week. Three patients (3.4%) in the Avalus™ group and 39 (10.8%) in the Magna™ group (p = 0.12) had severe patient–prosthesis mismatch at 1 week postoperatively. Conclusions The new Avalus™ stented aortic valve bioprosthesis was associated with good in-hospital outcomes and good valve functionality post-SAVR in Japanese patients.

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.

scholarly journals St. Jude Trifecta Versus Carpentier-Edwards Perimount Magna valves for the treatment of aortic stenosis: comparison of early Doppler-Echocardiography and hemodynamic performance

2015 ◽  
Vol 80 (3) ◽  
Author(s):  
Giovanni Minardi ◽  
Amedeo Pergolini ◽  
Giordano Zampi ◽  
Giovanni Pulignano ◽  
Gaetano Pero ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Doppler Echocardiography ◽  
Bioprosthetic Valve ◽  
Effective Orifice Area ◽  
Orifice Area ◽  
Hemodynamic Profile ◽  
Hemodynamic Performance

Objective. Aim of this study was to compare the hemodynamic profiles of 2 aortic valve bioprostheses: the Carpentier Edwards Perimount Magna (CEPM) valve and the Trifecta valve. Methods. 100 patients who underwent AVR for severe symptomatic AS between September 2011 and October 2012 were analyzed by means of standard trans-thoracic Doppler-echocardiography. Results. Mean and peak gradients were significantly lower for the 21 mm Trifecta vs CEPM (11 ± 4 vs 15 ± 4 mmHg, and 20 ± 6 vs 26 ± 7 mmHg, respectively; all p &lt; 0.05) and the 23 mm Trifecta vs CEPM (8 ± 2 vs 14 ± 4 mmHg, and 17 ± 6 vs 25 ± 9 mmHg; all p &lt; 0.05). Effective orifice area tended to be slightly higher for the Trifecta valve. Conclusion. The new bioprosthetic valve Trifecta has an excellent hemodynamic profile, and lower trans-prosthesic gradients when compared to CEPM valve.

Doppler Echocardiographic Evaluation of Prosthetic Valves in Tricuspid Position

2003 ◽  
Vol 11 (3) ◽  
pp. 193-197 ◽  
Author(s):  
Shigeaki Aoyagi ◽  
Hiroshi Tomoeda ◽  
Hiroshi Kawano ◽  
Shogo Yokose ◽  
Shuji Fukunaga
Keyword(s):  
Pressure Gradient ◽  
Doppler Echocardiography ◽  
Peak Velocity ◽  
Half Time ◽  
Prosthetic Valves ◽  
Echocardiographic Evaluation ◽  
Mechanical Prostheses ◽  
Doppler Data ◽  
Mean Pressure ◽  
The Mean

Doppler echocardiographic characteristics of 29 normally functioning prosthetic valves (23 mechanical, 6 biological) and 8 obstructed mechanical prostheses in the tricuspid position are reported. In normally functioning prostheses, peak velocity, mean pressure gradient, and pressure-half time were 1.25 ± 0.18 m·sec−1, 2.6 ± 1.1 mm Hg, and 122.6 ± 30.7 msec, respectively. Although no significant differences were seen in peak velocity and mean pressure gradient between mechanical and biological valves, the pressure half-time was significantly greater in biological valves. All normally functioning prostheses had a mean pressure gradient ⩽5.5 mm Hg and pressure half-time < 200 msec. In obstructed bileaflet valves, peak velocity was 1.66 ± 0.28 m·sec−1, mean pressure gradient was 6.1 ± 2.8 mm Hg, and pressure half-time was 265.8 ± 171.7 msec. These Doppler data were significantly greater than those in normally functioning valves where the mean pressure gradient was ⩽5.1 mm Hg and the pressure half-time was ⩽156 msec in all except one patient. Pathological obstruction of a tricuspid prosthesis can be strongly suspected in patients with a mean pressure gradient > 5.5 mm Hg and a pressure half-time > 200 msec on Doppler echocardiography.

A theoretical study of viscous effects in peristaltic pumping

1994 ◽  
Vol 279 ◽  
pp. 177-195 ◽  
Author(s):  
Alden M. Provost ◽  
W. H. Schwarz
Keyword(s):  
Wave Propagation ◽  
Pressure Gradient ◽  
Flow Rate ◽  
Mean Flow ◽  
Viscous Effects ◽  
Transverse Waves ◽  
Peristaltic Pumping ◽  
Mean Pressure ◽  
Flow Through ◽  
The Mean

Intuition and previous results suggest that a peristaltic wave tends to drive the mean flow in the direction of wave propagation. New theoretical results indicate that, when the viscosity of the transported fluid is shear-dependent, the direction of mean flow can oppose the direction of wave propagation even in the presence of a zero or favourable mean pressure gradient. The theory is based on an analysis of lubrication-type flow through an infinitely long, axisymmetric tube subjected to a periodic train of transverse waves. Sample calculations for a shear-thinning fluid illustrate that, for a given waveform, the sense of the mean flow can depend on the rheology of the fluid, and that the mean flow rate need not increase monotonically with wave speed and occlusion. We also show that, in the absence of a mean pressure gradient, positive mean flow is assured only for Newtonian fluids; any deviation from Newtonian behaviour allows one to find at least one non-trivial waveform for which the mean flow rate is zero or negative. Introduction of a class of waves dominated by long, straight sections facilitates the proof of this result and provides a simple tool for understanding viscous effects in peristaltic pumping.

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