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Early detection and accurate estimation of aortic stenosis (AS) severity are the most important predictors of successful long-term outcomes in patients. Current clinical parameters used for evaluation of the AS severity have several limitations including flow dependency. Estimation of AS severity is specifically challenging in patients with low-flow and low transvalvular pressure gradient conditions. A proper diagnosis in these patients needs a comprehensive evaluation of the left ventricle (LV) hemodynamic loads. This study has two objectives: (1) developing a lumped-parameter model to describe the ventricular-valvular-arterial interaction and to estimate the LV stroke work (SW); (2) introducing and validating a new index, the normalized stroke work (N-SW), to assess the global hemodynamic load imposed on the LV. N-SW represents the global hemodynamic load that the LV faces for each unit volume of blood ejected. The model uses a limited number of parameters which all can be measured non-invasively using current clinical imaging modalities. The model was first validated by comparing its calculated flow waveforms with the ones measured using Cardiovascular Magnetic Resonance (CMR) in 49 patients and 8 controls. A very good correlation and concordance were found throughout the cycle (median root mean square: 12.21 mL/s) and between the peak values (r = 0.98; SEE = 0.001, p

Low ejection fraction (EF) and low flow as determined by an echocardiographic stroke volume index (SVi) <35 mL/m2 are associated with low transvalvular gradients and increased mortality in both severe aortic stenosis (AS) and post–transcatheter aortic valve replacement (TAVR). Absence of an elevated echocardiographic transaortic gradient post-TAVR is considered a marker of procedural success despite the absence of data on its impact on mortality. The authors sought to examine the association of invasive and echocardiographic gradients post-TAVR with all-cause mortality in relation to flow and EF. In a multicenter retrospective registry of patients undergoing TAVR, Cox models with regression splines explored the relationship between invasive and echocardiographic gradients post-TAVR with 2-year mortality. An invasive gradient <5 mm Hg was considered low, between ≥5 and <10 mm Hg was considered intermediate, and ≥10 mm Hg was considered high. An echocardiographic gradient <10 mm Hg was considered low, ≥10 and <20 mm Hg was considered intermediate, and ≥20 mm Hg was considered high. Higher mortality occurred in low echocardiographic gradients at discharge relative to intermediate gradients (P < 0.001), and low gradient was associated with lower EF and echocardiographic SVi (P < 0.001 and P < 0.008, respectively). Lower mortality occurred in low invasive gradients relative to intermediate gradients (P = 0.012) with no difference in EF and echocardiographic SVi between groups (P = 0.089 and P = 0.947, respectively). There were insufficient observations to determine the impact of high echocardiographic and invasive gradients on mortality. In this large retrospective analysis, the impact of transaortic gradients on mortality after TAVR was not linear and complex, showing opposite results among echocardiographic and invasive measurements in low-gradient patients. [Display omitted] [ABSTRACT FROM AUTHOR]

Physiologic right ventricle–pulmonary artery (RV-PA) coupling may be impaired in patients with aortic stenosis (AS). This study aimed to assess the incidence and prognostic significance of impaired RV-PA coupling in low-risk patients with symptomatic severe AS undergoing transcatheter aortic valve replacement or surgical aortic valve replacement. RV-PA coupling was measured by transthoracic echocardiography as the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP) in patients in the PARTNER (Placement of Aortic Transcatheter Valve) 3 trial. The primary endpoint was the composite of all-cause mortality, stroke, and rehospitalization at the 2-year follow-up. Among 570 low-risk patients included in the analysis, RV-PA uncoupling was defined by a TAPSE/PASP ratio ≤ 0.55 mm/mm Hg. At baseline, 222 of 570 (38.9%) patients had RV-PA uncoupling. At 2 years, patients with baseline RV-PA uncoupling had an increased incidence of the primary endpoint (19.1% vs 9.9%, P = 0.002), all-cause mortality (5.9% vs 0.6%, P < 0.001), cardiovascular mortality (4.1% vs 0.6%, P = 0.003), and rehospitalization (13.5% vs 7.3%, P = 0.018). On multivariable analysis, baseline RV-PA uncoupling remained an independent predictor of the primary endpoint at 2 years (HR: 1.92; 95% CI: 1.04-3.57; P = 0.038). In patients with symptomatic severe AS at low surgical risk undergoing transcatheter aortic valve replacement or surgical aortic valve replacement, baseline RV-PA uncoupling defined by TAPSE/PASP ≤ 0.55 mm Hg was associated with adverse clinical outcomes at 2 years, including all-cause mortality, cardiovascular mortality, and rehospitalization. [Display omitted] [ABSTRACT FROM AUTHOR]

Patients with aortic valve stenosis (AS) may experience angina pectoris even if they have angiographically normal coronary arteries. Angina is associated with a marked increase in the risk of sudden death in AS patients. Only a few in vitro models describing the interaction between the left ventricular and aortic pressures, and the coronary circulation have been reported. These models were designed for specific research studies and they need to be improved or modified when other specific studies are required. Consequently, we have developed an in vitro model that is able to mimic the coronary circulation in presence of aortic stenosis. First, we have validated the model under physiological conditions. Then, we have examined and quantified the hemodynamic effects of different degrees of AS (from normal to severe AS) on the coronary flow using a model of the normal left coronary artery. In the coronary in vitro model without AS (normal valve), the amplitude and shape of coronary flow were similar to those observed in in vivo measurements obtained under physiological conditions, as described by Hozumi et al. (1998, 'Noninvasive Assessment of Significant Left Anterior Descending Coronary Artery Stenosis by Coronary Flow Velocity Reserve With Transthoracic Color Doppler Echocardiography,' Circulation, 97, pp. 1557-1562). The presence of an AS induced an increase in the maximum and mean coronary flow rates (97% and 73%, respectively, for a very severe AS). Furthermore, when AS was very severe, a retrograde flow occurred during systole. This study allowed us to validate our coronary in vitro model under physiological conditions, both in the absence and presence of AS. These changes could explain the fact that even if patients have angiographically normal epicardial coronary arteries, we can observe the occurrence of angina pectoris in these patients in the presence of an AS. [DOI: 10.1115/1.4000990] Keywords: left coronary artery, aortic valve stenosis, in vitro model

The regulation of phosphate (Pi) handling is crucial during calcification of the aortic valve. Gene profiling of Pi transporters revealed that VIC culture expresses SLC201A1/Pit1 and SLC20A2/Pit2. On exposure to a mineralizing medium (2 mM Pi), the expression of Pi transporters in VIC culture is increased several folds, with the highest magnitude for SLC20A1. By using siRNAs, we established that silencing SLC20A1 significantly reduced Pi-induced mineralization of VICs. In human pathological specimens, we found that the expression of SCL20A1 was increased in CAVD tissues compared to control non-mineralized aortic valves. Treatment of VIC culture with Pi promoted the loss of mitochondrial membrane potential (ΔΨm) and cytochrome c release within the cytosol, leading to apoptosis. Inhibition of Pi transporters with phosphonoformic acid (PFA) prevented Pi-mediated apoptosis of VICs. Moreover, we discovered that the level of the Akt-1 transcript is diminished in CAVD tissues compared with control valves. Accordingly, treatment with Pi caused a reduction of the Akt-1 transcript in VIC culture, and treatment with PFA or siRNA against SLC20A1 restored the level of Akt-1. Overexpression of Akt-1 (pCMVAkt-1) prevented both Pi-induced apoptosis and mineralization of VIC culture. These results strongly suggest that overexpression of SLC20A1 promotes apoptosis and mineralization by altering the level of Akt-1.

The development of human calcified aortic stenosis (AS) includes age-dependent processes that have been involved in atherosclerosis, such as infiltration of macrophages in aortic valves, which then promote production of many pro-inflammatory cytokines, including resistin. However, the molecular mechanisms contributing to these processes are not established. Since Sirt1 has been shown to modulate macrophage biology and inflammation, we examined its levels in human AS and tested its impact on resistin expression. Sirt1 mRNA (p = 0.01) and protein (p

Prosthesis-patient mismatch (PPM) is present when the effective orifice area of the inserted prosthetic valve is too small in relation to body size. Its main hemodynamic consequence is to generate higher than expected gradients through normally functioning prosthetic valves. The purpose of this review is to present an update on the present state of knowledge with regards to diagnosis, prognosis and prevention of PPM. PPM is a frequent occurrence (20%–70% of aortic valve replacements) that has been shown to be associated with worse hemodynamics, less regression of left ventricular hypertrophy, more cardiac events, and lower survival. Moreover, as opposed to most other risk factors, PPM can largely be prevented by using a prospective strategy at the time of operation.