OBJECTIVE: To determine the impact of pressure recovery (PR) adjustment on disease severity grading in patients with severe aortic stenosis. The authors hypothesized that accounting for PR would result in echocardiographic reclassification of aortic stenosis severity in a significant number of patients.
METHODS: A retrospective observational study between October 2013 and February 2021.
METHODS: A single-center, quaternary-care academic center.
METHODS: Adults (≥18 years old) who underwent transcatheter aortic valve implantation (TAVI).
METHODS: TAVI.
RESULTS: A total of 342 patients were evaluated in this study. Left ventricle mass index was significantly greater in patients who continued to be severe after PR (100.47 ± 28.77 v 90.15 ± 24.03, p = < 0.000001). Using PR-adjusted aortic valve area (AVA) resulted in the reclassification of 81 patients (24%) from severe to moderate aortic stenosis (AVA >1.0 cm2). Of the 81 patients who were reclassified, 23 patients (28%) had sinotubular junction (STJ) diameters >3.0 cm.
CONCLUSIONS: Adjusting calculated AVA for PR resulted in a reclassification of a significant number of adult patients from severe to moderate aortic stenosis. PR was significantly larger in patients who reclassified from severe to moderate aortic stenosis after adjusting for PR. PR appeared to remain relevant in patients with STJ ≥3.0 cm. Clinicians need to be aware of PR and how to account for its effect when measuring pressure gradients with Doppler.

In confined environments such as aircraft, an increase in mass impacts the overall system\'s performance, thus requiring sophisticated management. To verify whether the performance characteristics of fire extinguishing systems used in aircraft are satisfied, in this study was built a 1:1 scale test model. We examined the influence of the initial charge state and nozzles. Further, it measured the pressure inside the pipelines and vessels where multiple nozzles are installed to identify the flow and diffusivity characteristics of HFC-125 inside the pipelines and vessels. At a charging ratio of 54%, the initial pressure drop was smaller, and the lowest pressure before the bubble release point appeared 0.26 s later than when the charging ratio was 76%. The average pressure of each nozzle was 275.8 kPa higher under a charging ratio of 54% than 76% and increased further when the average concentration change was 54%, indicating that diffusivity increased. Although improvements occurred according to the charging ratio, the improvements according to the HFC-125 charging mass were more significant.

BACKGROUND: The role of echocardiography in deriving transvalvular mean gradients from transaortic velocities in aortic stenosis (AS) and in structural valve degeneration (SVD) is well established. However, reports following surgical aortic valve replacement, post-transcatheter aortic valve replacement (TAVR), and valve-in-valve-TAVR (ViV-TAVR) have cautioned against the use of echocardiography-derived mean gradients to assess normal functioning bioprosthesis due to discrepancy compared with invasive measures in a phenomenon called discordance.
METHODS: In a multicenter study, intraprocedural echocardiographic and invasive mean gradients in AS, SVD, post-native TAVR, and post-ViV-TAVR were compared, when obtained concomitantly, and discharge echocardiographic gradients were recorded. Absolute discordance (intraprocedural echocardiographic - invasive mean gradient) and percent discordance (intraprocedural echocardiographic - invasive mean gradient/echocardiographic mean gradient) were calculated. Multivariable regression analysis was performed to determine variables independently associated with elevated postprocedure invasive gradients ≥20 mm Hg, absolute discordance >10 mm Hg, and discharge echocardiographic mean gradient ≥20 mm Hg.
RESULTS: A total of 5,027 patients were included in the registry: 4,725 native TAVR and 302 ViV-TAVR. Intraprocedural concomitant echocardiographic and invasive mean gradients were obtained pre-TAVR in AS (n = 2,418), pre-ViV-TAVR in SVD (n = 101), in post-ViV-TAVR (n = 77), and in post-TAVR (n = 823). Echocardiographic and invasive mean gradients demonstrated strong correlation (r = 0.69) and agreement (bias, 0.11; 95% CI, -0.4-0.62) in AS, moderate correlation (r = 0.56) and agreement (bias, 1.08; 95% CI, -2.53 to 4.59) in SVD, moderate correlation (r = 0.61) and weak agreement (bias, 6.47; 95% CI, 5.08-7.85) post-ViV-TAVR, and weak correlation (r = 0.18) and agreement (bias, 3.41; 95% CI, 3.16-3.65) post-TAVR. Absolute discordance occurs primarily in ViV-TVR and is not explained by sinotubular junction size and increases with increasing echocardiographic mean gradient. Percent discordance in AS and SVD (1.3% and 4%, respectively) was lower compared with post-TAVR/ViV-TAVR (66.7% and 100%, respectively). Compared with self-expanding valves, balloon expanding valves were independently associated with elevated discharge echocardiographic but lower invasive mean gradient (odds ratio = 3.411, 95% CI, 1.482-7.852, P = .004; vs odds ratio = 0.308, 95% CI, 0.130-0.731, P = .008, respectively).
CONCLUSIONS: Post-TAVR/ViV-TAVR, echocardiography is discordant from invasive mean gradients, and absolute discordance increases with increasing echocardiographic mean gradient and is not explained by sinotubular junction size. Percent discordance is significantly higher post-TAVR/ViV-TAVR than in AS and SVD. Post-TAVR/ViV-TAVR, poor correlation and wide limits of agreement suggest echocardiographic and invasive mean gradients may not be used interchangeably and a high residual echocardiographic mean gradient should be confirmed invasively before considering any additional procedure to \"correct\" the gradient. Transcatheter aortic valve replacement valve types have variable impact on echocardiographic and invasive mean gradients.

Echocardiography-based transvalvular mean pressure gradient (ECHO-mPG) used to assess the forward valve function and structural valve deterioration could overestimate the true pressure gradient. This study evaluated the discrepancy between invasive and ECHO-mPG after transcatheter aortic valve implantation (TAVI) with respective valve type and size, its impact on a device success criterion, and predictors of a pressure discrepancy.
We analyzed 645 patients registered in a multicenter TAVI registry (balloon-expandable valve [BEV]: 500; self-expandable valve [SEV]: 145). The invasive transvalvular mPG was measured after valve implantation using two Pigtail catheters (CATH-mPG), while the ECHO-mPG was measured within 48 h after TAVI. Pressure recovery (PR) was calculated using the following formula: ECHO-mPG × effective orifice area (EOA)/ascending aortic area (AoA) × (1 - EOA/AoA).
ECHO-mPG was weakly correlated with (r = 0.29, p < 0.0001), and consistently overestimated CATH-mPG in both BEV and SEV, and respective valve sizes. The magnitude of the discrepancy was larger for BEV than SEV (p < 0.001) and smaller valves (p < 0.001). After the correction of PR using the above formula, the pressure discrepancy remained for BEV (p < 0.001) but not SEV (p = 0.10). The proportion of patients with an ECHO-mPG > 20 mmHg decreased from 7.0% to 1.6% after correction (p < 0.0001). Among the baseline and procedural variables, post-procedural ejection fraction, BEV versus SEV, and smaller valves were associated with a larger discrepancy in mPG.
ECHO-mPG could be overestimated after TAVI, especially in patients with a smaller BEV. A higher ejection fraction, BEV, and smaller valves were predictors of a pressure discrepancy between CATH- and ECHO-mPG.

Mosaic valve shows higher pressure gradient after aortic valve replacement compared to other same size labeled prostheses in postoperative echocardiogram. The purpose of this study was to evaluate the mid-term echocardiogram findings and long-term clinical outcomes of patients receiving a 19 mm Mosaic. Forty-six aortic stenosis patients receiving 19 mm Mosaic and 112 patients receiving either 19 mm Magna or Inspiris, who underwent mid-term follow-up echocardiogram were included in the study. Mid-term hemodynamic measurements evaluated by trans-thoracic echocardiogram and long-term outcomes were compared. Patients receiving Mosaic were significantly older (Mosaic: 76 ± 5.1 years vs. Magna/Inspiris: 74 ± 5.5 years, p = 0.046) and had smaller body surface area (Mosaic: 1.40 ± 0.114m2 vs. Magna/Inspiris: 1.48 ± 0.143m2, p < 0.001). There were no significant differences in comorbidities and medications. Post-operative echocardiogram performed at 1 week after the surgery showed higher maximum pressure gradient in patients receiving Mosaic (Mosaic: 38 ± 13.5 mmHg vs. Magna/Inspiris: 31 ± 10.7 mmHg, p = 0.002). Furthermore, mid-term echocardiogram follow-up performed at median duration of 53 ± 14.9 months after the surgery continuously showed higher maximum pressure gradient in patients receiving Mosaic (Mosaic: 45 ± 15.6 mmHg vs. Magna/Inspiris: 32 ± 13.0 mmHg, p < 0.001). However, there were no significant difference in changes in left ventricular mass from baseline in both groups. Kaplan-Meyer curve also showed no difference in long-term mortality and major adverse cardiac and cerebrovascular event between the two groups. Although the pressure gradient across the valve evaluated by echocardiogram was higher in 19 mm Mosaic compared to 19 mm Magna/Inspiris, there were no significant differences in left ventricular remodeling and long-term outcomes between the two groups.

Decisions in the management of aortic stenosis are based on the peak pressure drop, captured by Doppler echocardiography, whereas gold standard catheterization measurements assess the net pressure drop but are limited by associated risks. The relationship between these two measurements, peak and net pressure drop, is dictated by the pressure recovery along the ascending aorta which is mainly caused by turbulence energy dissipation. Currently, pressure recovery is considered to occur within the first 40-50 mm distally from the aortic valve, albeit there is inconsistency across interventionist centers on where/how to position the catheter to capture the net pressure drop.
We developed a non-invasive method to assess the pressure recovery distance based on blood flow momentum via 4D Flow cardiovascular magnetic resonance (CMR). Multi-center acquisitions included physical flow phantoms with different stenotic valve configurations to validate this method, first against reference measurements and then against turbulent energy dissipation (respectively n = 8 and n = 28 acquisitions) and to investigate the relationship between peak and net pressure drops. Finally, we explored the potential errors of cardiac catheterisation pressure recordings as a result of neglecting the pressure recovery distance in a clinical bicuspid aortic valve (BAV) cohort of n = 32 patients.
In-vitro assessment of pressure recovery distance based on flow momentum achieved an average error of 1.8 ± 8.4 mm when compared to reference pressure sensors in the first phantom workbench. The momentum pressure recovery distance and the turbulent energy dissipation distance showed no statistical difference (mean difference of 2.8 ± 5.4 mm, R2 = 0.93) in the second phantom workbench. A linear correlation was observed between peak and net pressure drops, however, with strong dependences on the valvular morphology. Finally, in the BAV cohort the pressure recovery distance was 78.8 ± 34.3 mm from vena contracta, which is significantly longer than currently accepted in clinical practise (40-50 mm), and 37.5% of patients displayed a pressure recovery distance beyond the end of the ascending aorta.
The non-invasive assessment of the distance to pressure recovery is possible by tracking momentum via 4D Flow CMR. Recovery is not always complete at the ascending aorta, and catheterised recordings will overestimate the net pressure drop in those situations. There is a need to re-evaluate the methods that characterise the haemodynamic burden caused by aortic stenosis as currently clinically accepted pressure recovery distance is an underestimation.

Transvalvular pressure gradient (ΔP) after aortic valve replacement is an important surrogate of aortic bioprostheses performance. Invasive ΔP is often measured after transcatheter aortic valve replacement to exclude patient-prosthetic mismatch. However, invasive aortic pressures are usually recorded in the pressure recovery (PR) zone downstream of the valve, potentially resulting in ΔP underestimation compared to noninvasive measurements. PR was extensively studied in straight ascending aortas. However, the impact of various aortic arch configurations on ΔP has not been explored. PR was assessed in a pulse duplicating simulator at various cardiac conditions of cardiac output, heart rates and pressures. Three different aortic geometries with identical root dimensions but with different aortic arches were used: (1) curvature 1, (2) curvature 2, and (3) straight aortic models. Instantaneous pressure and peak ΔP measurements were recorded incrementally along the models for each cardiac condition. The models with aortic arches produced two distinct PR zones (after the valve and after the aortic arch), whereas the model without an aortic arch produced only one PR zone (after the valve). The trend of the pressure and ΔP curves for each model was independent of the cardiac condition used, but the individually measured pressure magnitudes did change with different conditions. In this study, we illustrated the differences in PR between distinct aortic curvatures and straight aorta. PR affects pressure and ΔP measurements. These effects are clear when recording aortic pressures by catheterization and echocardiography.

Relevant pressure recovery (PR) has been shown to increase functional stenotic aortic valve orifice area and reduce left ventricular load. However, little is known about the relevance of PR in the pulmonary artery. The study examined the impact of PR using 2D-echocardiography in the pulmonary artery distal to the degenerated homograft in patients after Ross surgery. Ninety-two patients with pulmonary homograft were investigated by Doppler echocardiography (mean time interval after surgery 31 ± 26 months). PR was measured as a function of pulmonary artery diameter determined by computed tomography angiography. Homograft orifice area, valve resistance, and transvalvular stroke work were calculated with and without considering PR. PR decreased as the pulmonary artery diameter increased (r = -0.69, p < 0.001). Mean PR was 41.5 ± 7.1% of the Doppler-derived pressure gradient (Pmax ), which resulted in a markedly increased homograft orifice area (energy loss coefficient index [ELCOI] vs. effective orifice area index [EOAI], 1.3 ± 0.4 cm2 /m2 vs. 0.9 ± 0.4 cm2 /m2 , p < 0.001). PR significantly reduced homograft resistance and transvalvular stroke work (822 ± 433 vs. 349 ± 220 mmHg × ml, p < 0.0001). When PR was considered, the correlations of the parameters used were significantly better, and 11 of 18 patients (61%) in the group with severe homograft stenosis (EOAI <0.6 cm2 /m2 ) could be reclassified as moderate stenosis. Our results showed that the Doppler measurements overestimated the degree of homograft stenosis and thus the right ventricular load, when PR was neglected in the pulmonary artery. Therefore, Doppler measurements that ignore PR can misclassify homograft stenosis and may lead to premature surgery.

BACKGROUND: 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.
OBJECTIVE: The authors sought to examine the association of invasive and echocardiographic gradients post-TAVR with all-cause mortality in relation to flow and EF.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.

UNASSIGNED: To evaluate the flow dynamics of self-expanding and balloon-expandable transcatheter aortic valves pertaining to turbulence and pressure recovery. Transcatheter aortic valves are characterized by different designs that have different valve performance and outcomes.
UNASSIGNED: Assessment of transcatheter aortic valves was performed using self-expanding devices (26-mm Evolut [Medtronic], 23-mm Allegra [New Valve Technologies], and small Acurate neo [Boston Scientific]) and a balloon-expandable device (23-mm Sapien 3 [Edwards Lifesciences]). Particle image velocimetry assessed the flow downstream. A Millar catheter was used for pressure recovery calculation. Velocity, Reynolds shear stresses, viscous shear stress, and pressure gradients were calculated.
UNASSIGNED: The maximal velocity at peak systole obtained with the Evolut R, Sapien 3, Acurate neo, and Allegra was 2.12 ± 0.19 m/sec, 2.41 ± 0.06 m/sec, 2.99 ± 0.10 m/sec, and 2.45 ± 0.08 m/sec, respectively (P < .001). Leaflet oscillations with the flow were clear with the Evolut R and Acurate neo. The Allegra shows the minimal range of Reynolds shear stress magnitudes (up to 320 Pa), and Sapien 3 the maximal (up to 650 Pa). The Evolut had the smallest viscous shear stress magnitude range (up to 3.5 Pa), and the Sapien 3 the largest (up to 6.2 Pa). The largest pressure drop at the vena contracta occurred with the Acurate neo transcatheter aortic valve with a pressure gradient of 13.96 ± 1.35 mm Hg. In the recovery zone, the smallest pressure gradient was obtained with the Allegra (3.32 ± 0.94 mm Hg).
UNASSIGNED: Flow dynamics downstream of different transcatheter aortic valves vary significantly depending on the valve type, despite not having a general trend depending on whether or not valves are self-expanding or balloon-expandable. Deployment design did not have an influence on flow dynamics.