Hinge Point Research Articles

A Hybrid Approach That May Facilitate the Repair of Traumatic Popliteal Artery Pseudoaneurysms.

Traumatic popliteal pseudoaneurysms may occur in accidents or as an iatrogenic complication of a total knee arthroplasty. Complications often arise in open repair because of distorted anatomy. Up to 22% of the patients may suffer above-knee amputation. Endovascular treatment has proven to be an effective solution. However, the long-term performance of stents at the hinge point of the popliteal artery is questionable. We present a hybrid technique that was used successfully in 2 cases. Our approach takes advantage of both open and endovascular techniques. At first, we apply a stent graft at the side of the injury to cover the arterial trauma and stop blood leakage to the aneurysm sac. This allows for a safer dissection and open repair. We clamp the artery proximally and distally, open the sac, extract the stent graft, and extend to a longitudinal arteriotomy. We then reconstruct the entire area with a standard in lay end-to-end anastomosis using a vein graft. This hybrid technique may reduce the risk of uncontrollable bleeding and allow for a safer nerve decompression. Repair of such injuries is technically demanding. A hybrid approach may reduce the risk of complications and offer excellent long-term outcomes. The hybrid approach to the treatment of traumatic popliteal pseudoaneurysms combines the advantages of both open and endovascular approaches. It may be possible to make an acute operation just as safe as an elective operation by implementing the proposed strategy. The procedure can be performed by surgeons of all levels, and patients may benefit from a safer surgical dissection with fewer complications and blood loss. This smart combination of standard techniques may prove invaluable in a hostile surgical environment where limb loss is likely.

Mechanistic Insights Revealed by YbtPQ in the Occluded State.

Recently, several ATP-binding cassette (ABC) importers have been found to adopt the typical fold of type IV ABC exporters. Presumably, these importers would function under the transport scheme of "alternating access" like those exporters, cycling through inward-open, occluded, and outward-open conformations. Understanding how the exporter-like importers move substrates in the opposite direction requires structural studies on all the major conformations. To shed light on this, here we report the structure of yersiniabactin importer YbtPQ from uropathogenic Escherichia coli in the occluded conformation trapped by ADP-vanadate (ADP-Vi) at a 3.1 Å resolution determined by cryo-electron microscopy. The structure shows unusual local rearrangements in multiple helices and loops in its transmembrane domains (TMDs). In addition, the dimerization of the nucleotide-binding domains (NBDs) promoted by the vanadate trapping is highlighted by the "screwdriver" action at one of the two hinge points. These structural observations are rare and thus provide valuable information to understand the structural plasticity of the exporter-like ABC importers.

Soft Tissue Stabilization of the Hinge Position for Lateral Closing-Wedge Distal Femoral Osteotomy: An Anatomic Study.

Soft tissue plays an important role in stabilizing the hinge point for osteotomy around the knee. However, insufficient data are available on the anatomic features of the soft tissue around the hinge position for lateral closing-wedge distal femoral osteotomy (LCWDFO). To (1) anatomically analyze the soft tissue around the hinge position for LCWDFO, (2) histologically analyze the soft tissue based on the anatomic analysis results, and (3) radiologically define the appropriate hinge point to prevent unstable hinge fracture based on the results of the anatomic and histological analyses. Descriptive laboratory study. In 20 cadaveric knees (age, 82.7 ± 7.8 years; range, 60-96 years), the soft tissue of the distal medial side of the femur was anatomically analyzed. The thicknesses of the periosteum and direct insertion of the adductor tendon (AT) were histologically examined and measured using an electron microscope. The thickness of the periosteum was visualized graphically, and the graph of the periosteum and radiograph of the knee were overlaid using image editing software. The appropriate hinge position was determined based on the periosteal thickness and attachment of the AT. The mean thickness of the periosteum of the metaphysis was 352.7 ± 58.6 µm (range, 213.6-503.4 µm). The overlaid graph and radiograph revealed that the thickness of the periosteum changed at the part corresponding to the transition between the diaphyseal and metaphyseal ends of the femur. The mean width of the AT attached to the distal medial femur from the adductor tubercle toward the distal direction was 7.9 ± 1.3 mm (range, 6.3-9.7 mm). Results indicated that the periosteum and AT support the hinge for LCWDFO within the area surrounded by the apex of the adductor tubercle and the upper border of the posterior part of the lateral femoral condyle. When the hinge point is located within the area surrounded by the apex of the adductor tubercle and the upper border of the posterior part of the lateral femoral condyle, these soft tissues work as stabilizers, and there is no risk of cutting into the joint space.

Capture mechanism of a multi-dimensional wave energy converter with a strong coupling parallel drive

Wave energy is a promising renewable energy source. How to improve wave energy capture efficiency is a key challenge of wave energy generation. A multi-dimensional wave energy converter (MDWEC) with a strong coupling parallel drive is proposed. The MDWEC can efficiently absorb wave energy through a multi-dimensional moving body driven by six parallel hydraulic cylinders. Based on the Lagrangian approach, high nonlinear strong coupling dynamic models of the MDWEC are established. The hydraulic cylinder force acting on the converter is deduced according to the principle of virtual work. The nonlinear hydrostatic restoring force for different submerged body geometry shapes is derived. The vertical restoring force caused by pitch and roll, the pitch and roll restoring torque caused by deviating from the equilibrium position, the coupled radiation force, and the coupled inertial force between pitch and surge are considered. The hydrodynamic performance, the motion response, and the transient power behavior are investigated. The upper and lower platform hinge point radius, the hinge point center angle, and conversion parameters are optimized based on a genetic algorithm. Wave power capture ability comparison with different design parameters, shapes, and wave states is presented. As the significant wave height decreases from 3 m to 1 m, the capture efficiency increases from 68.3% to 79.1%. The capture ability of MDWEC with semiellipsolid is the highest. Compared with a heaving cone converter, the MDWEC improves the capture efficiency by 47.5% with a significant wave height of 1 m and an energy period of 4 s.

Deformed Popliteal Artery Due to Highly Flexed Knee Position Can Cause Kinks, Creating an Unfavorable Hemodynamic State.

Endovascular treatment devices of the femoropopliteal artery have evolved, improving clinical results. However, the effects of dynamic changes in the popliteal artery during knee flexion have not been sufficiently investigated. In this study we performed a 3-dimensional analysis to clarify the dynamic changes in the popliteal artery during knee flexion and their effects on hemodynamics.Methods and Results: To analyze dynamic changes in the popliteal artery in the knee flexion position, a computed tomography protocol was developed in the right-angled and maximum flexion knee positions. Thirty patients with lower extremity artery disease were recruited. V-Modeler software was used for anatomical and hemodynamic analyses. Various types of deformations of the popliteal artery were revealed, including hinge points and accessory flexions. Kinks can occur in the maximum flexion position; however, they rarely occur in the right-angled flexion position. In addition, hemodynamic analysis revealed a tendency for lower minimum wall shear stress and a higher maximum oscillatory shear index at the maximum curvature of the popliteal artery. Kinks in the maximum flexion position suggested that the outcome of endovascular treatment may change in areas such as Japan, where knee flexion is customary. Hemodynamics at the maximum curvature of the popliteal artery indicated that the luminal condition was unfavorable for endovascular treatment.

Dynamic simulation analysis of working equipment of small backhoe hydraulic excavator

To further improve the performance of a company’s excavator, reduce the production cost, and simplify the complex process of dynamic modeling, a 13-ton small backhoe hydraulic excavator working device was taken as the research object, and a virtual prototype was established by using Pro/E and ADAMS software. The excavation resistance was calculated and the STEP function was defined, the dynamic simulation analysis was carried out during the working process of the excavator, and the stress change curve of the hinge point was obtained, which reduced the calculation amount, and provided a reference for the finite element analysis and optimization design of the working device of the excavator.

Mitral Annular Disjunction: Review of an Increasingly Recognized Mitral Valve Entity.

Mitral annular disjunction (MAD) refers to atrial displacement of the hinge point of the mitral valve annulus from the ventricular myocardium. MAD leads to paradoxical expansion of the annulus in systole and may often be associated with mitral valve prolapse (MVP), leaflet degeneration, myocardial and papillary muscle fibrosis, and, potentially, malignant cardiac arrhythmias. Patients with MAD and MVP may present similarly, and MAD is potentially the missing link in explaining why some patients with MVP experience adverse outcomes. Patients with a 5 mm or longer MAD distance have an elevated risk of malignant cardiac arrhythmia compared with those with a shorter MAD distance. Evaluation for MAD is an important component of cardiac imaging, especially in patients with MVP and unexplained cardiac arrhythmias. Cardiac MRI is an important diagnostic tool that aids in recognizing and quantifying MAD, MVP, and fibrosis in the papillary muscle and myocardium, which may predict and help improve outcomes following electrophysiology procedures and mitral valve surgery. This article reviews the history, pathophysiology, controversy, prevalence, clinical implications, and imaging considerations of MAD, focusing on cardiac MRI. Keywords: MR-Dynamic Contrast Enhanced, Cardiac, Mitral Valve, Mitral Annular Disjunction, Mitral Valve Prolapse, Floppy Mitral Valve, Cardiac MRI, Arrhythmia, Sudden Cardiac Death, Barlow Valve © RSNA, 2023.

Research on Lifting Characteristics of Flat-Head Jib Tower Crane Based on Hydraulic Luffing Force

This paper investigates a design and computational method for its lifting characteristics using the flathead jib tower crane as a research object. We use a mechanical model based on classical mechanical theory and derive the expression for the characteristic lifting equation. The influence of different hinge points of the hydraulic cylinder on the boom and other hinge points of the hydraulic cylinder on the slewing frame on the lifting characteristics is discussed by using MATLAB with examples, providing a theoretical benchmark for calculating the bearing characteristics of the flat head jib tower crane.

Impact of diagnosis-to-ablation time on atrial fibrillation recurrence: most pronounced in the first 3 years after diagnosis and clinically irrelevant thereafter

Abstract Objectives To assess the impact of the diagnosis-to-ablation time (DAT) on AF recurrence in search of lower and upper DAT thresholds. Background DAT is a strong, modifiable predictor of atrial fibrillation (AF) recurrence after ablation. Whether this association holds any lower and/or upper limits is yet unknown. Methods A total of 2000 AF patients from two cohorts of 1000 consecutive patients each (69% males, age 62±10 years) undergoing pulmonary vein isolation (PVI) between 2005-2014 and 2017-2019 were followed for 3 years. Results Clinical success, defined as freedom of documented AF was achieved in 61.7% of the patients. Median DAT decreased over time from 36 (Q1-Q3: 12-72) months in the first cohort to 12 (Q1-Q3: 5-48) in the second (P<0.001). A multivariable Cox proportional hazards fitted model of AF recurrence rate in relation to DAT (range 0-288 months) demonstrated a steep rise in AF recurrence from 27 to 40% in the first 36 months (d%/dt=0.36), with a first hinge point at 36 months and a less steep rise to 45% until 90 months (d%/dt=0.09), with flattening beyond 90 months (d%/dt=0.026). Conclusions The association between DAT and AF recurrence has no lower limit (‘the shorter the better’) while little gain is to be expected beyond a DAT of 36 months (‘the longer the more clinically irrelevant’). Our data advocate for a PVI as early as possible, certainly within 3 years of AF diagnosis.3-year AF recurrence rate versus DAT

Cardiac magnetic resonance imaging in athletes with suspected structural myocardial disease: results of a high volume single-center study

Abstract Introduction Structural heart disease is one of the leading causes of sudden cardiac death in athletes. Cardiac magnetic resonance imaging (CMR) has a key role in the diagnosis, providing accurate functional and morphological information. Aim To investigate the prevalence of structural heart disease and the etiology of sudden cardiac death (SCD) in athletes. Methods We enrolled athletes (training ≥6 hours/week) who underwent CMR due to suspected structural myocardial disease at our Heart and Vascular Center between 2009 and 2022. We also performed cardiogenetic testing with new-generation sequencing (174 genes) in athletes with confirmed structural heart disease and/or malignant arrhythmia who gave consent. Results CMR was performed on a total of 556 athletes (445 male, 24±10 age). The indications for CMR were as follows: aborted sudden cardiac death/sustained ventricular tachycardia (3%), ECG (46%) or echocardiographic abnormality (36%), positive family history of SCD or cardiomyopathy (CMP) (3%), or athletes' complaints (31%). Structural myocardial abnormalities were confirmed in 99 athletes: hypertrophic (HCM) in 27, arrhythmogenic (AC) in 11, dilated (DCM) CMP in 7, and left ventricular non-compaction (LVNC) in 9 cases. MR images consistent with Fabry disease were found in 5 patients. We have discovered post-myocardial infarction scars in 10 cases, and atypical non-ischemic scarring (excluding hinge point fibrosis) was observed in 32 athletes. Besides pathological abnormalities, minor alterations were identified in 76 patients. Among the athletes examined after aborted sudden cardiac death/sustained ventricular tachycardia (n=18), we found structural heart disease in 14 patients, AC was confirmed in 7, HCM in two, non-ischemic fibrosis in three cases and LVNC in one athlete. Cardiogenetic test was performed in 26 athletes, we found pathogenic or likely pathogenic mutations in 5 cases, typical of HCM, AC, DCM (MYBPC3, PKP2, LMNA, TTN). The genetic test showed VUS (variant of unknown significance) in 15 additional athletes. Conclusions HCM was identified as the most frequent CMP, whereas AC and nonischaemic scar was the leading cause of SCD or SVT in our athletes.Figure A)Short axis late gadolinium ehancement CMR image of a 26-year-old female tennis player with hypertrophic cardiomyopathy and nonischemic fibrosis (arrow) and MYBPC3 pathogenic variant.Figure B)Short axis late gadolinium enhancement CMR image of a 40-year-old male elite discus thrower with sustained ventricular tacchycardia and nonischaemic scar formation (arrows). LMNA and titin pathogenic variants could be detected.

Feasibility of Co-locating wave energy converters with offshore aquaculture: The Pioneering case study of China's Penghu platform

As the aquaculture industry moves further offshore, there is an increasing prospect of co-locating wave energy converters (WECs) with offshore aquaculture. In China, the multi-use of wave energy and offshore aquaculture has already been implemented and demonstrated commercially. A thorough analysis of the power performance and dynamic and structural responses on the Penghu platform is performed in this paper to improve the understanding of the co-locating potential. The analysis is based on the potential flow theory, multi-body constrained dynamics equations, and quasi-static finite element analysis (FEA) method. It is found that powering offshore aquaculture operations is possible using wave energy paired with solar energy. In addition, the inclusion of WECs can, to some extent, reduce the platform motion, making visits to the aquaculture site more feasible. The inner pool wave elevation is slightly reduced compared to the free surface elevation outside Penghu, which is conducive to aquaculture operations. It is also shown that the structural design of the Penghu platform is very safe. Still, the hinge points must be seriously considered because of the possibility of fatigue fracture. Overall, co-locating WECs and offshore aquaculture is demonstrated as a feasible solution to the power supply problems of offshore aquaculture.

Design of a Redundant 6-DOF Parallel Platform for Mirror Precision Pose Adjustment

The pose control of 6-DOF parallel mechanism depends on the measurement accuracy of the position of the active driving strut, which affects the pose control accuracy of 6-DOF parallel mechanism. In order to overcome the influence of heavy load large impact force on the measurement accuracy of the active drive strut, a redundant 6-DOF parallel mechanism that separates the measurement struts from the active drive struts was proposed. The fixed platform and the moving platform are connected by six identical active drive struts and six redundant measurement struts. The active driving strut is an active motion unit used to achieve various pose movements of the parallel mechanism, and the follower redundant measurement strut is a precision measurement unit, and does not constrain any DOF of the platform. Only the follower accurately measures the distance between the upper and lower hinge points of the redundant hinges. The accurate position and pose of the 6-DOF parallel mechanism are obtained by using the forward kinematics solution. The controller is used to implement the pose closed-loop control algorithm to achieve precise pose control. The design of this redundant 6-DOF parallel mechanism improves the movement accuracy of the parallel mechanism under heavy load. It can be applied to the precision adjustment of the primary mirror or secondary mirror under heavy load in large aperture optics, and has strong engineering application value.

941 A Systematic Review of Surgical Intervention Criteria for Thoracic Aortic Aneurysms

Abstract Aim Elective surgical repair of thoracic aortic aneurysms (TAAs) is the only treatment that prevents dissection or rupture. Current guidelines from the American College of Cardiology/American Heart Association and the European Society of Cardiology, recommend an aortic diameter threshold of 5.5cm for surgical intervention of TAAs. Recent studies have questioned the efficacy of current guidelines as they highlighted that the majority of dissections occur before reaching the threshold. This review aims to determine if an aortic diameter of 5.5cm is an appropriate threshold for prophylactic surgical repair of non-syndromic ascending TAAs. Method A search of Ovid MEDLINE and Pubmed databases was performed. Search terms included “ascending thoracic aortic aneurysm”, “ATAA”, “aortic diameter” and “aortic size paradox”. Non-English papers, animal studies and case reports were excluded. Reference lists from each article were assessed for further literature which met the inclusion criteria. Results 22 studies were included. Four themes emerged from these papers which support lowering the threshold for prophylactic surgery: quantifying the changes in aortic diameter that occur during dissection, the discovery of the aortic size paradox, the identification of a new hinge point, and the improved safety of modern surgery. Regardless of this evidence, it appears to be unjustified to lower the threshold based on relative risk calculations. Conclusions Despite current guidelines, the use of aortic diameter as a risk assessment tool for TAAs is inadequate. Multiple studies have shown the ineffectiveness of a 5.5cm threshold, suggesting revision of current surgical guidelines is warranted.

Higher fibular head is a risk for lateral hinge fracture in medial open wedge high tibial osteotomy.

To examine the association between the hinge position, fibular head position, and type III lateral hinge fracture (LHF) in patients with knee osteoarthritis (OA) who underwent medial open wedge high tibial osteotomy (MOWHTO). This retrospective study examined patients who underwent MOWHTO. Radiographically, the Kellgren-Lawrence (K/L) classification, distance between the articular surface and the tip of the fibular head (fibular head position), hinge point (hinge position), type of LHF, and safe zone (within the proximal tibiofibular joint) outlier were evaluated. To determine the cut-off value of the hinge position and fibular head position associated with type III LHF, a receiver operating characteristic (ROC) curve analysis was performed. The odds ratio (OR) was calculated from the obtained cut-off values using logistic regression, which was adjusted by age, gender, body mass index, and opening distance. Among 132 knees in 120 patients, the radiographic severity of knee OA was 19 (14%), 73 (55%), and 40 (30%) of K/L grades 2, 3, and 4, respectively. LHF was observed in 40 knees (30%), including types I, II, and III fractures in 21 (16%), 5 (4%), and 14 (11%) knees, respectively. Hinge and fibular head positions were 16 and 10mm, respectively, with significant correlation. Safe zone outlier was observed in 38 knees (29%). The hinge and fibular head positions with type III LHF were significantly higher (more cranial) than those with no fracture or other LHF subtypes. The ROC curve revealed that the cut-off value for the hinge and fibular head positions was 13.3 and 8.6mm, respectively. The OR of the hinge and fibular head positions was 22.42 and 13.86, respectively. A higher hinge position was a risk factor for type III LHF and was associated with a higher fibular head in patients with knee OA who underwent MOWHTO. The hinge position should be placed at a certain distance from the articular surface to avoid type III LHF, especially in participants with higher fibular head position, even if the hinge position is located in the safe zone. Retrospective cohort study, Level III.

Lateral Distance From the Osteotomy Hinge Point to the Tibial Cortex Is Associated With Lateral Hinge Fracture Type and Fracture Occurrence Time After Medial Open-Wedge High Tibial Osteotomy

To verify whether the distance from the hinge point to the tibial cortex affects the occurrence time and characteristics of the lateral hinge fracture (LHF) in medial open-wedge high tibial osteotomy. We retrospectively reviewed 171 knees in 171 patients (121 women, 50 men; mean age, 53.9 years; range, 36-67 years) who had undergone medial open-wedge high tibial osteotomy with locking plate fixation between January 2011 and December 2020. Osteotomy hinge point and LHFs were identified on intraoperative fluoroscopy and immediate postoperative radiographs. LHF type was classified as suggested by Takeuchi etal. Acute fracture was defined as a fracture that occurred during surgery, and delayed fracture was defined as a fracture observed after 1 month postoperatively. The nearest distances from osteotomy hinge point to lateral, distal, and proximal cortex were measured on postoperative radiographs. We compared the distance between the different types and between acute and delayed LHFs. There were 55 LHFs (32%) (type I, 40 knees; type II, 14 knees; type III, 1 knee) that occurred acutely in 41 knees and were found as delayed fractures in 14 knees. The patient demographics were not significantly different between non-LHFs and each type of LHFs. Proximal and distal distances were not statistically different among fracture types and between occurrence times. However, lateral distances were significantly shorter in type I LHFs (6.2 ± 1.8 mm) and longer in type II LHFs (9.3 ± 2.3 mm) than in non-LHFs (7.1 ± 2.7 mm) (P= .020 and .004, respectively). The lateral cortical distances were also different between acute LHFs (6.4 ± 1.9 mm) and delayed LHF (9.0 ± 2.7 mm) (P < .001). In the case of fracture type, the frequency of type I decreases with increase in the lateral distance, whereas that of type II increases with increase in the lateral cortical distance. In acute fracture, type I was dominant (85.4%), whereas in delayed fracture, type II was dominant (57.2%). The lateral cortical distance from the hinge point was significantly associated with LHF occurrence. Shorter distance increased the risk for acute type I LHF, whereas longer distance increased the risk for delayed type II LHFs. Level III, retrospective comparative prognostic trial.

Error Analysis of a New Five-Degree-of-Freedom Hybrid Robot

The error analysis of the robot has a very practical significance for improving its accuracy. Therefore, this paper conducts an error analysis for a new five-degree-of-freedom hybrid robot designed to conduct responsible surface machining. Initially, the error sources of the hybrid robot were sorted out to determine the number of error sources. Then, the error mapping model of the hybrid robot is established by the closed-loop vector method and the first-order perturbation method. Based on the mapping property of the 6th-order velocity Jacobi matrix, the compensable and non-compensable error sources affecting the posture error at the end of the hybrid robot are separated. Finally, the error analysis of the separated error sources is carried out to study the effect of single error sources and multiple error sources coupled with the posture error at the end of the robot. The results show that among the individual error sources, the dynamic and fixed platform hinge position error has the most significant effect on the end of the robot; among the integrated posture errors after coupling multiple error sources, the position of the dynamic and fixed platform hinge position error and the translational joint initial position dominate; the analysis of the different trajectories also yields that the error introduced by each error source increases gradually with the increase of the end trajectory. When designing this hybrid robot, attention should be paid to the manufacturing and installation accuracy of the dynamic and fixed platform hinge point positions and the translational joint initial position.

Automated correction angle calculation in high tibial osteotomy planning

High tibial osteotomy correction angle calculation is a process that is usually performed manually or in a semi-automated way. The process, according to the Miniaci method, is divided into several stages to find specific points: the center of the femoral head, the edges of the tibial plateau, the Fujisawa point, the center of the ankle joint, and the Hinge point. In this paper, we proposed an end-to-end approach that consists of different techniques for finding each point. We used YOLOv4 to detect regions of interest. To identify the center of the femoral head, we used the YOLOv4 and the Hough transform. For the other points, we used a combined method of YOLOv4 with the ASM/AAM algorithm and YOLOv4 with image processing algorithms. Our fully-automated method achieved a mean error rate of 0.5^{circ } (0^{circ }–2.76^{circ }) ICC 0.99 (0.98–0.99) 95% CI on our own dataset of standing long-leg Anterior Posterior view X-rays. This might be the first method that automatically calculates the correction angle of high tibial osteotomy.

Mitral Annular Disjunction: A Scoping Review.

Mitral annular disjunction (MAD) is the atrial displacement of the mitral valve (MV) hinge point, especially along the posterior mitral leaflet, which leads to inhomogeneous blood flow into the left ventricle, causing chronic fibrotic changes, malignant arrhythmias, and even sudden cardiac arrest. Some studies suggest that MAD is a part of normal heart morphology; however, the origin is still controversial. MAD commonly occurs with MV prolapse and myxomatous degenerative MV disease. In almost 20% of cases, MAD can occur independently as well. The prevalence of MAD in normal hearts varies from 8.6% to 96%, depending on the imaging modality and the cutoff used to define MAD. Transthoracic echocardiography is often the initial screening test, but the low sensitivity of transthoracic echocardiography to identify MAD makes it easy to miss the diagnosis altogether. More advanced imaging, especially cardiac MRI, is the gold standard for diagnosing MAD and risk stratification. MAD is an independent predictor of malignant arrhythmia. Among patients with MAD, risk stratification is based on the age at diagnosis, previous syncopal attacks, premature ventricular contractions, papillary muscle fibrosis, and longitudinal disjunction distance. Most asymptomatic patients are managed conservatively; however, radiofrequency ablation should be considered in patients with high-risk or symptomatic MAD due to the risk of ventricular arrhythmias and sudden cardiac death.

Shear Behaviour of Fibreglass Rock Bolts for Various Pretension Loads

In this paper, after determining an appropriate experimental design and testing scheme to test the shear performance suitably, the impacts of pretension and shear interfaces on fibreglass rock bolts were investigated. For this purpose, at the first stage, the double shear testing apparatus was modified to address the issues and shortcomings of the established testing methodology. Then, 20-tonne and 30-tonne rock bolts were tested with pretension loads of 0 kN, 10 kN, 15 kN, and 20 kN for each test scheme. For this, a 40 MPa small aggregate concrete was used for all samples to simulate the host rock. The grout used to anchor the rock bolts was mixed to the product’s recommended guidelines to ensure close resemblance to field mixtures. To maintain consistency, all samples were manufactured with the same concrete and grout recipes. The results of double shear tests revealed that increasing the pretension also increased the confining pressures at the shear interfaces for clean joints. This, in turn, reduced the damage propagating from the bolt at the shear interface and decreased the hinge point bending. The results can be applied for further analytical and numerical studies, which could utilise for a better understanding of the shear behaviour of fibreglass rock bolts.

Systolic anterior motion of the anterior mitral valve leaflet begins in subclinical hypertrophic cardiomyopathy.

Anterior mitral valve leaflet (AMVL) elongation is detectable in overt and subclinical hypertrophic cardiomyopathy (HCM). We sought to investigate the dynamic motion of the aorto-mitral apparatus to understand the behaviour of the AMVL and the mechanisms of left ventricular outflow tract obstruction (LVOTO) predisposition in HCM. Cardiovascular magnetic resonance imaging using a 1.5 Tesla scanner was performed on 36 HCM sarcomere gene mutation carriers without left ventricular hypertrophy (G+LVH-), 31 HCM patients with preserved ejection fraction carrying a pathogenic sarcomere gene mutation (G+LVH+), and 53 age-, sex-, and body surface area-matched healthy volunteers. Dynamic excursion of the aorto-mitral apparatus was assessed semi-automatically on breath-held three-chamber cine steady-state free precession images. Four pre-defined regions of interest (ROIs) were tracked: ROIPMVL: hinge point of the posterior mitral valve leaflet; ROITRIG: intertrigonal mitral annulus; ROIAMVL: AMVL tip; and ROIAAO: anterior aortic annulus. Compared with controls, normalized two-dimensional displacement-vs.-time plots in G+LVH- revealed subtle but significant systolic anterior motion (SAM) of the AMVL (P < 0.0001) and reduced longitudinal excursion of ROIAAO (P = 0.014) and ROIPMVL (P = 0.048). In overt and subclinical HCM, excursion of the ROITRIG/AMVL/PMVL was positively associated with the burden of left ventricular fibrosis (P < 0.028). As expected, SAM was observed in G+LVH+ together with reduced longitudinal excursion of ROITRIG (P = 0.049) and ROIAAO (P = 0.008). Dyskinesia of the aorto-mitral apparatus, including SAM of the elongated AMVL, is detectable in subclinical HCM before the development of LVH or left atrial enlargement. These data have the potential to improve our understanding of early phenotype development and LVOTO predisposition in HCM.