scholarly journals Impact of arterio–ventricular interaction on first-phase ejection fraction in aortic stenosis

2020 ◽  
Author(s):  
Eigir Einarsen ◽  
Johannes J Hjertaas ◽  
Haotian Gu ◽  
Knut Matre ◽  
Philip J Chowienczyk ◽  
...  
Keyword(s):  
Linear Regression ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Strain Rate ◽  
Myocardial Contractility ◽  
Volume Index ◽  
Lower Strain Rate ◽  
Lower Strain ◽  
Arterial Load ◽  
Jet Velocity

Abstract Aims  First-phase ejection fraction (EF1), the EF at the time to peak aortic jet velocity, has been proposed as a novel marker of peak systolic function in aortic stenosis (AS). This study aimed to explore the association of myocardial contractility and arterial load with EF1 in AS patients. Methods and results  Data from a prospective, cross-sectional study of 114 patients with mild, moderate, and severe AS with preserved left ventricular EF (>50%) were analysed. EF1 was measured as the volume change from end-diastole to the time that corresponded to peak aortic jet velocity. Myocardial contractility was assessed by strain rate measured by speckle tracking echocardiography. Arterial stiffness was assessed by central pulse pressure/stroke volume index ratio (PP/SVi). The total study population included 48% women, median age was 73 years, and mean peak aortic jet velocity was 3.47 m/s. In univariable linear regression analyses, lower EF1 was associated with higher age, higher peak aortic jet velocity, lower global EF, lower global longitudinal strain, lower strain rate, and higher PP/SVi. There was no significant association between EF1 and heart rate or sex. In multivariable linear regression analysis, EF1 was associated with lower strain rate and higher PP/SVi, independent of AS severity. Replacing PP/SVi by valvular impedance did not change the results. Conclusion  In patients with AS, reduced myocardial contractility and increased arterial load were associated with lower EF1 independent of the severity of valve stenosis.

scholarly journals Hot Workability of 300M Steel Investigated by In Situ and Ex Situ Compression Tests

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 880 ◽  
Author(s):  
Rongchuang Chen ◽  
Haifeng Xiao ◽  
Min Wang ◽  
Jianjun Li
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Working ◽  
Ex Situ ◽  
Lower Strain Rate ◽  
Hot Workability ◽  
Compression Tests ◽  
300M Steel ◽  
Lower Strain

In this work, hot compression experiments of 300M steel were performed at 900–1150 °C and 0.01–10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

Influence of Mg Content, Grain Size and Strain Rate on Mechanical Properties and DSA Behavior of Al-Mg Alloys Processed by ECAP and Annealing

2014 ◽  
Vol 794-796 ◽  
pp. 870-875 ◽  
Author(s):  
Min Zha ◽  
Yan Jun Li ◽  
Ragnvald H. Mathiesen ◽  
Christine Baumgart ◽  
Hans J. Roven
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Uniform Elongation ◽  
Mg Alloys ◽  
Lower Strain Rate ◽  
Lower Strain ◽  
Mg Content ◽  
Al Mg Alloys

Ultrafine-grained (UFG) binary Al-xMg (x=1, 5 and 7 wt %) alloys were processed by equal channel angular pressing (ECAP) at room temperature via route Bccombined with inter-pass annealing. The effects of Mg content, grain size and strain rate on mechanical properties and dynamic strain aging (DSA) behaviour of the Al-Mg alloys upon tensile testing at room temperature were studied. An increase in Mg content from 5 to 7 wt % leads to a pronounced increase in strength and uniform elongation in both the as-homogenized and as-ECAP Al-Mg alloys. Thereby, the Al-7Mg alloy, either prior to or after ECAP processing, possess significantly higher strength and comparable or even higher uniform elongation than the more dilute Al-Mg alloys. However, the as-ECAP Al-Mg alloys exhibit significantly higher strength but little work hardening and hence rather limited uniform elongation. In general, decreasing grain size leads to significant increase in strength while dramatic decrease in ductility. Moreover, DSA serration amplitudes increase with reducing grain size in the micrometer range. However, the UFG Al-Mg alloys exhibit much less DSA effect than the micrometer scaled grain size counterparts, i.e. probably due to the high dislocation densities and special grain boundary features in the UFG materials. Also, the Al-Mg alloys, especially those with a UFG structure, exhibit higher strength and ductility at lower strain rate than at higher strain rate, due mainly to enhanced DSA effect and hence work hardening at a lower strain rate.

scholarly journals Use of passive leg rise as an add-on to dobutamine in patients with paradoxical low-flow, low-gradient aortic stenosis

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
E Buffle ◽  
A Papadis ◽  
C Seiler ◽  
S F De Marchi
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Low Flow ◽  
Volume Index ◽  
Aortic Valve Area ◽  
Low Ejection Fraction ◽  
Valve Area

Abstract Background Dobutamine has been proposed for the assessment of low-flow, low-gradient aortic stenosis (LFLGAS). However, in 1/3 of patients, no increase in stroke volume index can be achieved by Dobutamine, thus hampering its diagnostic value. This study evaluated the manoeuvre of cardiac preload augmentation by passive leg rise (PLR) alone or on top of Dobutamine to increase stroke volume index (SVI) in patients with LFLGAS, particularly in paradoxical LFLGAS. Methods We examined 50 patients with LFLGAS. Patients were assigned to the paradoxical LFLGAS (Paradox) group if left ventricular ejection fraction (LVEF) was ≥50% (n=29) and to the LFLGAS with low ejection fraction (LEF) group if LVEF was <50% (n=21). A modified Dobutamine stress echocardiography was performed in all patients with the following 4 steps: Rest, PLR alone, maximal Dobutamine infusion rate alone (Dmax) and Dobutamine plus PLR (Dmax + PLR). Three SVI measurement methods were used: first the left ventricular outflow tract velocity time integral (LVOT VTI) method, second the 2D Simpson's method, and third the 3D method. The corresponding aortic valve area (AVA) was obtained by the continuity equation. The increase of those values compared to measurements at rest was calculated and compared between the 3 stress steps. Results In the paradoxical LFLGAS group, delta SVI with Dmax assessed by both Simpson's (depicted in the figures) and 3D method was lowest compared to PLR and Dmax + PLR. PLR alone yielded an equally high delta SVI as Dmax + PLR in Simpson's and 3D, and was at least as high as Dmax across all methods. Dobutamine alone yielded the lowest delta transaortic aortic valve VTI. The highest delta aortic valve area resulted for Dmax + PLR. In the LEF group, the three stress steps yielded an equally high delta SVI with Simpson's method. Dmax never yielded a higher delta SVI than PLR alone. The yielded delta SVI was the highest for Dmax + PLR for both LVOT VTI and 3d method, although the difference was overall not as strong as in the Paradox group. Conclusions In patients with paradoxical LFLGAS, Dobutamine alone is inadequate for testing the potential of aortic valve opening augmentation. Instead, PLR alone or the addition of PLR plus Dobutamine should be used for that purpose. In low LVEF, adding PLR to Dobutamine also seems useful although its diagnostic added value is less evident than in the Paradox group. FUNDunding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Gottfried und Julia Bangerter-Rhyner-Foundation Paradox group Low ejection fraction group

scholarly journals Longitudinal changes in cardiac morphology and function in women with INOCA: results from repeat cardiac magnetic resonance imaging a median of 6 years apart

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
S K Zamani ◽  
J Wei ◽  
A C Kwan ◽  
D S Berman ◽  
C Shufelt ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cardiac Magnetic Resonance ◽  
Ejection Fraction ◽  
Strain Rate ◽  
Volume Index ◽  
Resonance Imaging ◽  
Cardiac Morphology ◽  
End Diastolic Volume ◽  
And Function

Abstract Background Women with signs and symptoms of ischemia but no obstructive coronary arteries (INOCA) are at increased risk of developing heart failure with preserved ejection fraction. The exact mechanism(s) driving disease progression, however, remains incompletely understood. Purpose To evaluate longitudinal changes in cardiac morphology and function across all four chambers of the heart, in women with INOCA. Methods To accomplish our goal, we leveraged 13 cases of repeat cardiac magnetic resonance imaging (cMRI), performed a median of 6 years apart (range: 3–11 years), in women with INOCA. Cardiac morphology and function were retrospectively assessed from conventional cine images using commercially available software (V5.11.1, CVI42, Circle Cardiovascular Imaging). Left and right ventricular (LV, RV, respectively) mass, volume, and ejection fraction were assessed using a series of short axis images spanning the base to apex. Left atrial (LA) volume was assessed using three orthogonal long-axis images, while right atrial (RA) area was assessed using a single horizontal long axis image. Concentricity was defined as the mass-to-end-diastolic volume ratio. Lastly, strain and strain rate were assessed in all four chambers by feature tracking analysis. Results Upon follow-up, LV and RV end-diastolic volume index (Figure 1A), LA volume index (from 36±5 to 32±5 mL/m2, P=0.02) and RA area index (from 11.3±1.6 to 9.6±2.0 cm2/m2, P=0.003) were significantly reduced. LV mass was preserved (Figure 1B), resulting in a significant increase in LV concentricity (from 0.59±0.07 to 0.64±0.09, P=0.02), together with an increase in LV ejection fraction (Figure 1C), and reduction in both longitudinal (Figure 1D) and circumferential (from 1.3±0.2 to 1.1±0.3 s-1, P=0.05) LV early diastolic strain rate. In contrast, RV mass was significantly reduced (Figure 1B), while RV concentricity (from 0.19±0.02 to 0.20±0.04) and ejection fraction (from 58±4 to 59±6) were preserved. Conclusions To our knowledge, this is the first study to evaluate long-term changes in cardiac morphology and function in women with INOCA. That LV early diastolic strain rate was reduced at follow-up, is consistent with a growing body of cross-sectional observations from our group and others, highlighting diastolic dysfunction as an important contributor of disease progression in this patient population. That we observed a discordant pattern of change between LV and RV concentricity is unique and warrants further consideration. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National heart, lung, and blood institute (NIH)

Left Ventricular Function Assessment by Strain Analysis in Patients with Severe Aortic Stenosis with Preserved Ejection Fraction Undergoing Aortic Valve Replacement – A Prospective Longitudinal Study at a Tertiary Health Care Centre of South India

2021 ◽  
Vol 8 (27) ◽  
pp. 2405-2411
Author(s):  
Syed Waleem Pasha ◽  
Narasimha D. Pai ◽  
Padmanabha Kamath ◽  
Ramanatha L. Kamath ◽  
Francis N.P. Monteiro
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Aortic Valve Replacement ◽  
Strain Rate ◽  
Valve Replacement ◽  
Longitudinal Strain ◽  
Global Longitudinal Strain ◽  
Left Ventricular ◽  
Study Population

BACKGROUND Aortic stenosis (AS) is the most common, single, native valvular heart disease in adult population. The purpose of this study was to detect abnormalities in global longitudinal strain (GLS) and strain rate using 2D - STI in patients with severe AS and preserved left ventricular ejection fraction (LVEF). The effect of aortic valve replacement (AVR) on changes in strain parameters 30 days after surgery was also analysed. METHODS A total number of 60 patients aged more than 18 years with aortic valve disease scheduled for surgical aortic valve replacement admitted in Department of Cardiology, KMC hospital Mangalore, were included over a period of 18 months from January 2017 to June 2018. RESULTS A total of 60 patients with severe AS, defined by an aortic valve area of < 1 cm², mean transaortic pressure gradient ( P) of > 40 mmHg and maximum aortic velocity (Vmax) of > 4 m/sec were studied. Mean age of the study population was 63.5 years. 60 % of the population were males and 40 % being females. Most common risk factor present in the study population was diabetes mellitus (DM). 83% of the patients in the study population had at least one symptom. Most common symptom with which the patients presented was exertional dyspnoea. All patients had normal left ventricle (LV) cavity dimensions and LVEF prior to surgery with diastolic dysfunction being present in all patients. The LV ejection fraction is not significantly altered. The aortic valve area calculated by continuity equation has significantly increased post AVR with a significant reduction in transaortic peak and means pressure gradients. Mean global longitudinal strain (GLS) improved from -15.1 % to - 16.9 % (P < 0.001) and longitudinal strain rate improved from -0.8 to -0.9/s (P < 0.001). CONCLUSIONS Global longitudinal strain and strain rate can be adequately measured by 2D speckle-tracking imaging and can be used to detect subtle changes of myocardial function in patients with severe AS with preserved LVEF. KEYWORDS Aortic Stenosis, Exertional Dyspnoea, Global Longitudinal Strain, Transaortic Pressure Gradient, Ventricular Hypertrophy

Abstract 87: Alterations to Cardiac Mechanics Do Not Preserve Normal Cardiac Function in a Novel Ossabaw Swine Model of Heart Failure with Preserved Ejection Fraction

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Jenna C Edwards ◽  
Madeleine Dionne ◽  
T. D Olver ◽  
Jan R Ivey ◽  
Pamela K Thorne ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Cardiac Function ◽  
Strain Rate ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Volume Index ◽  
Lv Function ◽  
Swine Model ◽  
Preserved Ejection Fraction

Introduction: Heart failure with preserved ejection fraction (HFpEF) is clinically characterized by an increased incidence in females and many comorbidities including type 2 diabetes (T2D) and obesity. Animal models accurately representing clinical HFpEF are lacking; thus, the purpose of this study was to examine left ventricular (LV) mechanics in a novel Ossabaw swine model of chronic pressure-overload (aortic-banding; AB) and T2D (Western diet; WD) using two dimensional speckle tracking echocardiography (2D-STE). We hypothesized that global LV strain would be decreased primarily in the longitudinal direction in WD-AB animals. Methods: Female Ossabaws were randomly divided into 2 groups: CON (n=5) and WD-AB (n=5). LV function and strain were measured at 1 year of age after 6 mo. of AB and 9 mo. of WD via pressure-volume relations and 2D-STE. Significance was set at P < 0.05 using t-test vs. CON. Results: In the WD-AB group, ejection fraction (EF%) and end diastolic volume were normal (>50%), and observed in parallel with increased LV weight, lung weight, and LV diastolic wall thickness (i.e. concentric hypertrophy). WD-AB group had increased HOMA-IR and body surface area, two common features in T2D. In WD-AB animals, although global longitudinal systolic strain rate and end systolic displacement were increased, stroke volume index was decreased. Early diastolic rotation rate was decreased, while global longitudinal late diastolic strain rate was increased in the WD-AB group. These changes, considered in parallel with an increased end diastolic pressure-volume relationship in WD-AB animals, are consistent with diastolic dysfunction. In contrast, longitudinal, radial, and circumferential early diastolic strain rates increased in the WD-AB group. Conclusion: Contrary to our hypothesis, LV longitudinal strain was increased during both systole and diastole, and observed in parallel with decreased early diastolic untwisting in WD-AB animals. Our results suggest alterations to LV mechanics do not preserve normal systolic and diastolic cardiac function, despite normal resting EF%, in this novel translational model of pressure-overload HF with potential relevance to human HFpEF including associated clinical comorbidities (sex, obesity, and T2D).

scholarly journals 621 Anemia and its impact on clinical, echocardiographic parameters and prognosis in patients with severe aortic stenosis and normal left ventricular ejection fraction

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
C Beladan ◽  
A Calin ◽  
A D Mateescu ◽  
M Rosca ◽  
R Enache ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ejection Fraction ◽  
Severe Aortic Stenosis ◽  
Nyha Class ◽  
Left Ventricular ◽  
Volume Index ◽  
All Cause Mortality ◽  
Echocardiographic Parameters ◽  
Study Population

Abstract Background Anemia is common in patients (pts) with severe aortic stenosis (AS). Untreated anemia and severe AS are individually associated with the development of heart failure, however data regarding the potential detrimental effect of anemia on left ventricular (LV) function and prognosis in pts with severe AS are controversial. Aim To investigate the impact of anemia on clinical status, echocardiographic parameters and prognosis in pts with severe AS and preserved LV ejection fraction (LVEF). Methods Consecutive patients with severe AS (aortic valve area [AVA] index ≤ 0.6 cm2/m2) and preserved LVEF (&gt;50%) referred to our echocardiography laboratory were prospectively screened. All patients underwent complete clinical examination and comprehensive echocardiography, including speckle tracking-derived measurements of LV and left atrial (LA) strain. Baseline clinical variables included NYHA class, cardiac risk factors, haemoglobin (Hb) level and glomerular filtration rates (GFR, by MDRD formula). The definition of anemia was based on gender-specific cut-off values, as recommended by the WHO (Hb &lt;13.0 g/dL for men, &lt;12.0 g/dL for women). Patients with more than mild aortic regurgitation or mitral valve disease, atrial fibrillation or cardiac pacemakers were excluded. Results The study population included 264 patients (pts) (66 ± 11 yrs, 147 men). Anemia was present in 64 pts (24%). Aortic valve replacement (AVR) was performed in 151 pts. Dividing the study population into 2 groups, according to the presence/absence of anemia, no significant differences were found between groups regarding: age (p = 0.09), body surface area (p = 0.6), LVEF (62 ± 7 vs 63 ± 6%, p = 0.2), LV Global Longitudinal Strain (-15.2 ± 4 vs -14.7 ± 3 %, p = 0.4), LV mass index (p = 0.9), mean aortic gradient (p = 0.2) and indexed AVA (0.40 ± 0.09 vs 0.39 ± 0.09 cm2/m2, p = 0.6), or presence of significant coronary artery disease (p = 0.9). Compared to pts with normal Hb level, in pts with anemia NYHA class (p = 0.03), brain natriuretic peptide values (p = 0.004), lateral E/e’(16.2 ± 6.9 vs 13.7 ± 6.3, p = 0.01) and average E/e" ratio (15.9 ± 5.9 vs 14.1 ± 5.3, p = 0.03), LA volume index (54.3 ± 16.9 vs 45.0 ± 12.1 ml/m2, p &lt; 0.001), and systolic pulmonary artery pressure (38 ± 13 vs 33 ± 8, p = 0.009) were all significantly higher. During a 3–years follow-up 47 pts died. Age, NYHA class, BNP serum level, baseline anemia, LA volume index and systolic pulmonary pressure were associated with all-cause mortality in the whole study group (p &lt; 0.03 for all). In the group of pts who underwent AVR, NYHA class was the only independent predictor of all-cause mortality. Conclusions In our study including pts with severe AS and preserved LVEF, patients with baseline anemia presented worse functional status and LV diastolic dysfunction and increased 3-year all-cause mortality compared to those with normal Hb levels. However, in pts who underwent surgical AVR, there was no impact of baseline anemia on 3-year survival.

Sign in / Sign up

Export Citation Format

Share Document