Numerical study on dynamic compressive deformation and elasto-plastic wave propagation of foam materials

Finite element models of closed-cell foam structures were created using the three-dimensional Voronoi tessellation method coupled with the random sequential addition algorithm. The dynamic compressive deformation behaviors of the models were numerically studied using LS-DYNA code. The deformation mode of the models changed gradually as the deformation rate increases. Also, the generation and the propagation of plastic wave was clearly observed with the rate of 100 m/s. The longitudinal elastic wave velocity showed a weak negative dependency on the deformation rate although the strain rate dependence of material properties was not considered. Furthermore, a prediction method for the dynamic stress state on the impact side based on the static stress-strain relationship was presented

Post-occlusional hyperemia for fractional flow reserve assessment and pull-back curve analysis

\u3cp\u3eBalloon occlusion is a potential method for inducing hyperemia to measure post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR). The objective of this study was to determine the clinical usefulness of post-occlusional hyperemia. FFRs measured using post-occlusional hyperemia caused by 30 (FFR\u3csub\u3eoccl30\u3c/sub\u3e) and 60 s (FFR\u3csub\u3eoccl60\u3c/sub\u3e) of balloon occlusion after PCI were compared in 60 lesions from 60 patients. The duration of hyperemia was also measured. There was a strong correlation between FFR\u3csub\u3eoccl30\u3c/sub\u3e and FFR\u3csub\u3eoccl60\u3c/sub\u3e (r = 0.969, p < 0.01). The duration of hyperemia was significantly longer with FFR\u3csub\u3eoccl60\u3c/sub\u3e than with FFR\u3csub\u3eoccl30\u3c/sub\u3e (68 ± 23 vs. 37 ± 15 s, p < 0.01). The time required for pullback curve analysis was around 45 s. However, in 7 (12%) cases, the duration of hyperemia with FFR\u3csub\u3eoccl60\u3c/sub\u3e was < 45 s, which was not enough for pull-back curve analysis. To predict the duration of hyperemia with FFR\u3csub\u3eoccl60\u3c/sub\u3e ≥ 45 s, the receiver operating characteristic curve analysis revealed a cut-off value of 25 s of hyperemia with FFR\u3csub\u3eoccl30\u3c/sub\u3e. FFR\u3csub\u3eoccl30\u3c/sub\u3e is sufficient for diagnostic purposes. FFR\u3csub\u3eoccl60\u3c/sub\u3e is suitable for pull-back curve analysis in select cases based on predictions made using the duration of hyperemia with FFR\u3csub\u3eoccl30\u3c/sub\u3e.\u3c/p\u3

Diagnostic performance of in-procedure angiography-derived quantitative flow reserve compared to pressure-derived fractional flow reserve: The FAVOR II Europe-Japan study

Background—Quantitative flow ratio (QFR) is a novel modality for physiological lesion assessment based on 3-dimensional vessel reconstructions and contrast flow velocity estimates. We evaluated the value of online QFR during routine invasive coronary angiography for procedural feasibility, diagnostic performance, and agreement with pressure-wire–derived fractional flow reserve (FFR) as a gold standard in an international multicenter study. Methods and Results—FAVOR II E-J (Functional Assessment by Various Flow Reconstructions II Europe-Japan) was a prospective, observational, investigator-initiated study. Patients with stable angina pectoris were enrolled in 11 international centers. FFR and online QFR computation were performed in all eligible lesions. An independent core lab performed 2-dimensional quantitative coronary angiography (2D-QCA) analysis of all lesions assessed with QFR and FFR. The primary comparison was sensitivity and specificity of QFR compared with2D-QCAusing FFR as a reference standard.A total of 329patients were enrolled. Paired assessment of FFR, QFR, and2DQCA was available for 317 lesions. Mean FFR, QFR, and percent diameter stenosis were 0.83±0.09, 0.82±10, and 45±10%, respectively. FFR was ≤0.80 in 104 (33%) lesions. Sensitivity and specificity by QFR was significantly higher than by 2D-QCA (sensitivity, 86.5% (78.4–92.4) versus 44.2% (34.5–54.3); P<0.001; specificity, 86.9% (81.6–91.1) versus 76.5% (70.3–82.0); P=0.002). Area under the receiver curve was significantly higher for QFR compared with 2D-QCA (area under the receiver curve, 0.92 [0.89–0.96] versus 0.64 [0.57–0.70]; P<0.001). Median time to QFR was significantly lower than median time to FFR (time to QFR, 5.0 minutes [interquartile range, –6.1] versus time to FFR, 7.0 minutes [interquartile range, 5.0–10.0]; P<0.001). Conclusions—Online computation of QFR in the catheterization laboratory is clinically feasible and is superior to angiographic assessment for evaluation of intermediary coronary artery stenosis using FFR as a reference standard. Clinical Trial Registration—URL: https://www.clinicaltrials.gov. Unique identifier: NCT02959814

Feasibility and safety of jailed‐pressure wire technique using durable optical fiber pressure wire for intervention of coronary bifurcation lesions

Objectives: The objective was to evaluate the safety, feasibility, and accuracy of the jailed-pressure wire technique using a durable optical fiber-based pressure wire with high-pressure dilatation using a non-compliant balloon after main vessel stenting. Background: Fractional flow reserve (FFR) information can help interventionists determine whether they should treat a jailed-side branch (SB). However, re-crossing a pressure wire into a jailed-SB is sometimes technically difficult. Methods: Fifty-one consecutive lesions from 48 patients who underwent the jailed-pressure wire technique were retrospectively investigated. The primary endpoint was complication rate and secondary endpoints included success rate of FFR measurement, incidence of wire disruption, and final drift rate. The usability of FFR for percutaneous coronary intervention of coronary bifurcation lesion was also evaluated. Results: Median age of the patients was 69 years and 80.4% were men. The most frequent underlying disease was stable angina (70.6%) and 68.6% were type B2 lesions. Our main findings were: the procedure was performed successfully in all cases without any complications or wire disruption, FFR could be measured without significant final drift in 95.9% of cases, and FFR measurements helped interventionists determine whether to perform a final kissing balloon dilatation in 49.0% cases. Conclusions: The jailed-pressure wire technique using a durable optical fiber-based pressure wire with high-pressure post-dilatation maneuver was safe, feasible, and accurate

Feasibility and safety of jailed-pressure wire technique using durable optical fiber pressure wire for intervention of coronary bifurcation lesions

Objectives: The objective was to evaluate the safety, feasibility, and accuracy of the jailed-pressure wire technique using a durable optical fiber-based pressure wire with high-pressure dilatation using a non-compliant balloon after main vessel stenting. Background: Fractional flow reserve (FFR) information can help interventionists determine whether they should treat a jailed-side branch (SB). However, re-crossing a pressure wire into a jailed-SB is sometimes technically difficult. Methods: Fifty-one consecutive lesions from 48 patients who underwent the jailed-pressure wire technique were retrospectively investigated. The primary endpoint was complication rate and secondary endpoints included success rate of FFR measurement, incidence of wire disruption, and final drift rate. The usability of FFR for percutaneous coronary intervention of coronary bifurcation lesion was also evaluated. Results: Median age of the patients was 69 years and 80.4% were men. The most frequent underlying disease was stable angina (70.6%) and 68.6% were type B2 lesions. Our main findings were: the procedure was performed successfully in all cases without any complications or wire disruption, FFR could be measured without significant final drift in 95.9% of cases, and FFR measurements helped interventionists determine whether to perform a final kissing balloon dilatation in 49.0% cases. Conclusions: The jailed-pressure wire technique using a durable optical fiber-based pressure wire with high-pressure post-dilatation maneuver was safe, feasible, and accurate