scholarly journals Simulation of the dynamic flow field in the left ventricle of the heart during diastolic filling

AIP Advances ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 025221
Author(s):  
Jianhua Adu ◽  
Lixue Yin ◽  
Hongmei Zhang ◽  
Shenghua Xie ◽  
Jing Lu
Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1198
Author(s):  
Pauline H. M. Janssen ◽  
Sébastien Depaifve ◽  
Aurélien Neveu ◽  
Filip Francqui ◽  
Bastiaan H. J. Dickhoff

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.


1979 ◽  
Vol 236 (2) ◽  
pp. H323-H330 ◽  
Author(s):  
D. Ling ◽  
J. S. Rankin ◽  
C. H. Edwards ◽  
P. A. McHale ◽  
R. W. Anderson

In eight chronically instrumented conscious dogs, apical and middle left ventricular transverse diameters were measured with pulse-transit ultrasonic dimension transducers. Intracavitary apical and midventricular pressures and intrapleural pressure were measured with micromanometers. Both diameters were normalized as a percent extension from the dimension at zero transmural pressure, determined during a transient vena caval occlusion. During the rapid phase of diastolic filling, there was a 2--5 mmHg pressure gradient from the midventricle to the apex. During late rapid filling, the apical transmural pressure and diameter increased more rapidly and reached diastasis 17 +/- 4 ms earlier than the corresponding midventricular measurements (P less than 0.01). The static diastolic pressure-dimension characteristics at the apical and midventricular levels were not significantly different (P greater than 0.30). The dynamic diastolic pressure-dimension relationship was also similar at the two levels and could be represented by a model incorporating parallel viscous properties. Because of regional differences in pressures and dimensions, however, the dynamic relationship could not be modeled when pressure was compared to the dimension at a different level. Thus, diastolic pressures should be measured at the same level as dimensions when assessing left ventricular diastolic mechanics.


1992 ◽  
Vol 124 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Kent A. Takemoto ◽  
Leslie Bernstein ◽  
Joseph F. Lopez ◽  
David Marshak ◽  
Shahbudin H. Rahimtoola ◽  
...  

1989 ◽  
Vol 118 (6) ◽  
pp. 1248-1258 ◽  
Author(s):  
Rick A. Nishimura ◽  
Martin D. Abel ◽  
Liv K. Hatle ◽  
David R. Holmes ◽  
Philippe R. Housmans ◽  
...  

2021 ◽  
Vol 23 (1) ◽  
pp. 17-23
Author(s):  
V. A. Lysenko

Chronic heart failure (CHF) does not lose its leading position among the problems of cardiovascular disease. Pathological cardiac remodeling combines the processes of hypertrophy and dilatation of cavities and is the main cause of heart failure progression, and consequently results in high cardiac mortality, especially in CHF patients with reduced left ventricular ejection fraction (LV EF). Despite a substantial range of studies on the features of structural and geometric remodeling of the heart, changes in systolic and diastolic function of the ventricles in CHF patients, this issue still presents a challenge and needs to be improved. The aim of the work – to examine changes in structural and geometric parameters and diastolic function of the heart in patients with CHF of ischemic genesis with reduced LV EF. Materials and methods. The study included 79 patients (men – n = 49; women – n = 30) with CHF of ischemic origin with reduced LV EF, sinus rhythm, stage II AB, NYHA II-IV FC (the main group), and 90 patients with coronary heart disease without signs of CHF (men – n = 40, 44.5 %; women – n = 50, 55.5 %), (the comparison group). The patient groups were age-, sex-, height-, weight-, body surface area-matched. Doppler echocardiographic examination was performed on the device Esaote MyLab Eight (Italy). Results. In CHF patients with reduced LV EF, the following indicators prevailed: EDD LV by 18 % (P = 0.001), LV EDV by 45.8 % (P = 0.001), LV EDV index by 44.6 % (P = 0.001), LV ESD by 44.9 % (P = 0.001), PW by 17.7 % (P = 0.001), LV mass index by 66.6 % (P = 0.001) according to the Penn Convention, and by 62.1 % (P = 0.001) according to the ASE; 16.1 % (P = 0.010) increased RV cavity without changes in its wall thickness. In patients with CHF of ischemic origin with reduced LV EF, the main types of LV geometry were: eccentric (70 %) and concentric (24 %) LV hypertrophy. More than half of the CHF patients with reduced LV EF had significant disorders of LV diastolic filling (25 % – “restrictive” and 28 % “pseudonormal”), a 2.3 times increase (P = 0.001) in E/e’ ratio, a 35 % (P = 0.014) increase in the left atrial volume index and 32 % (P = 0.0001) – in pulmonary capillary wedge pressure (PCWP), increased mean and systolic pressure in the pulmonary artery by 1.5 times (P = 0.002) and 1.6 times (P = 0.0001), respectively. Conclusions. Structural and geometric remodeling of the left ventricle in patients with CHF of ischemic origin with reduced LV EF occurs due to an increase in LV myocardial mass via thickening of its walls and cavity dilatation (44.6 % (P = 0.001) increase in the LV EDV index), as well as 66.6 % (P = 0.001) increase in LV mass index with the predominance of eccentric (70 %) and concentric hypertrophy (24 %) over other types of LV geometry. Severe disorders of LV diastolic filling (25 % – “restrictive” and 28 % “pseudonormal”) are attributable to the significant increase in end-diastolic pressure in the left ventricle (2.3 times increase (P = 0.001) in E/e´) with the development of postcapillary pulmonary hypertension (1.5 times increase (P = 0.002) in the mean and 1.6 times (P = 0.0001) – in systolic pressure in the pulmonary artery).


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